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The synthesis and characterization of new sulfoxide complexes of ruthenium and their potential as anti-cancer… Yapp, Donald Tshin Tsun 1993

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THE SYNTHESIS AND CHARACTERIZATION OFNEW SULFOXIDE COMPLEXES OFRUTHENIUM AND THEIR POTENTIALAS ANTI-CANCER AGENTSbyDONALD TSHIN TSUN YAPPB.Sc., The University of Victoria, 1987A THESIS SUBMITTED IN PARTIAL FULFILMENT OFTHE REQUIREMENTS FOR THE DEGREE OFDOCTOR OF PHILOSOPHYinTHE FACULTY OF GRADUATE STUDIESDEPARTMENT OF CHEMISTRYWe accept this thesis as conformingto the required standardTHE UNIVERSITY OF BRITISH COLUMBIAJUNE 1993© Donald Tshin Tsun Yapp, 1993In presenting this thesis in partial fulfilment of the requirements for an advanceddegree at the University of British Columbia, I agree that the Library shall make itfreely available for reference and study. I further agree that permission for extensivecopying of this thesis for scholarly purposes may be granted by the head of mydepartment or by his or her representatives. It is understood that copying orpublication of this thesis for financial gain shall not be allowed without my writtenpermission.(Signature) Department of ^(.146MIs re The University of British ColumbiaVancouver, CanadaDate^,T(.4 e^0^/991DE-6 (2/88)( CILR0 0g^g_RIIDM30^TM30^BMSF., R^WASP, R MeBESS, R - EtBPSE. R - PrFigure showing the ablreviations used for some sulfoxides;S and 0 in the text imply S- and 0- bonded su/foxides, respectively.AbstractAreas of hypoxia (low 02 content) within malignant tumours are often resistantto radiotherapy and chemotherapy. Compounds that work in conjunction with radiationor alone are required to remove or define hypoxic areas. The complexes cis-RuC12(DMS0)3(DMSQ) (1) and cis-RuC12(TMa0)4 (3) (the figure shows the sulfoxidestructures) were previously used as precursors for the synthesis of Ru(II)-sulfoxide-nitroimidazole complexes. The structural chemistry and spectroscopic data ofRu/DMSO/TMSO complexes are reviewed. RuC12(TM50)4, previously assigned a transgeometry, is shown to be cis; two crystal forms are characterized crystallographically.Two bromo-Ru(II) complexes ofTMSO, [RuBr3(TMS0)4Li]2 andtrans-RuBr2(TMS0)4, are isolated,and both compounds aresubsequently characterized by X-raycrystallography. The dimer containsfour kinds of coordinated TMSO ligands: the formulation is best written as[Br6(TMS0)2Ru2(//2-TMS0)(//3-TMS0)2Li2(TMSS2)2], and reveals a unique 113-typesulfoxide ligand.The dinuclear, mixed valence Ru-sulfoxide complexes Ru2C15(Et2S0)4,Ru2C15(nPr2S 0)5 and Ru2C15(nBu2S0)5, and monomeric Ru(III) complexes of nPr2S0and Ph2S0 are synthesized and characterized spectroscopically. The two Ru(III)complexes are structurally characterized as [11(nPr2SQ)2litrans-RuC14(nPr250)2] andmer-RuC13(Ph250)(Ph2SQ)(Me0H). The former complex reveals the presence of acation containing the strongly hydrogen-bonded nPr2S0-11-0SnPr moiety; the lattercomplex reveals a coordinated methanol ligand (H-bonded to the 0 atom of Ph2S0), aswell as both sulfur- and oxygen-bonded Ph2S0 ligands.Four ruthenium (II) complexes of chelating sulfoxides are also synthesized andstructurally characterized. The data for the complexes trans-RuC12(BMSE)2 (4), cis-RuC12(BESE)2 (5), trans-RuC12(BPSE)2 (6) and cis-RuC12(BMSP)2 (7) reveal in eachcase only S-bonded sulfoxides. The unit cell of complex 4, in addition, contains a watermolecule strongly hydrogen-bonded to two chloride atoms from two different moleculesof the complex.Seven of the characterized Ru-sulfoxide complexes (1 - 7) are tested in vitrousing Chinese hamster ovary (CHO) cells. The biological data indicate that thecomplexes accumulate in CHO cells, without hypoxic selectivity. No toxicity isobserved at the complex concentrations used (1.0 mM for 1 - 4, 7; 0.50 mM for 5 and6) despite evidence that all seven complexes bind to DNA. Of some interest, the trans-complexes (2, 4, 6) accumulate in CHO cells and bind to DNA to a greater degree thanthe cis complexes.111Table of ContentsAbstract ^Table of Contents ^  ivList of Tables ^ xviList of Figures ^ xviiiList of Schemes ^ xxiList of Abbreviations ^  xxiiAcknowledgements ^  xxvChapter 1: General Introduction ^  11.1 Preamble ^  11.2 Cancer  11.3 Treatments ^  21.4 Hypoxia - Definition and Problems ^  41.5 Radiation and the Oxygen Effect  5iv1.6 Sulfhydryl Compounds as Radioprotectors ^  91.7 Overcoming the Problem of Hypoxic Cells  111.8 Chemotherapy ^  111.9 Chemical Radiosensitizers ^  121.9.1 Hypoxic Cell Sensitizers ^  131.9.2 Nitroimidazoles as Hypoxic Cell Sensitizers ^ 141.9.3 Targeting Radiosensitizers to DNA ^ 161.10 Other Chemotherapeutic Agents ^  171.10.1 DNA Binders ^  171.10.2 Hypoxic Cytotoxins  181.10.3 Targeting Metals to Hypoxic Areas ^ 191.11 Metal Complexes as Anti-Cancer Agents  201.11.1 Cisplatin: Pros and Cons ^  201.11.2 Metals in Biological Systems  211.11.3 Metal Complexes vs. Organic Compounds ^ 231.11.4 Electron Affinity of Drugs in Radiosensitization ^ 231.11.5 Lability as a Function of Oxidation State ^ 251.11.6 Radioisotopes for Imaging ^  261.12 Non-Platinum Metal Complexes as Anti-Cancer Agents ^ 261.13 Ruthenium Sulfoxides ^  291.14 Ruthenium Sulfoxides as Anti-Cancer Agents ^ 331.14.1 Cis-RuC12(DMS0)3(DMSD)  33V1.14.2 Trans-RuC12(DMa0)4 ^  341.15 The Aims and Evolution of the Project ^  36Chapter 2: The Synthesis and Characterization of Sulfoxides andSulfoxide Complexes of Ru(ll) and Ru(III) ^  392.1 Chemicals and Reagents ^  392.2 Physical Techniques and Methods ^  392.3 Synthesis of the Sulfoxides^  402.3.1 Diethylsulfoxide  412.3.2 1,2-Bis(methylsulfinyl)ethane (BMSE) ^ 412.3.3 1,2-Bis(ethylsulfinyl)ethane (BESE)  422.3.4 1,2-Bis(propylsulfinyl)ethane (BPSE) ^ 422.3.5 1,3-Bis(methylsulfinyl)propane (BMSP)  432.3.6 1,4-Bis(methylsulfinyl)butane (BMSB) ^ 442.3.7 1,4-Bis(ethylsulfinyl)butane (BESB)  442.4 Synthesis of the Monodentate Sulfoxide Complexes of Ruthenium^452.4.1 The "Ruthenium-Blue" Solutions ^  452.4.2 Cis-RuC12(DMS0)4 ^  452.4.3 Trans-RuC12(DM50)4  472.4.4 Ru2C16(DMS0)4 ^  472.4.5 Ru2C14(DMS0)5  482.4.6 Cis-RuC12(TMS0)4^  49vi2.4.7 [RuBr3(I'MS0)4Li]2 ^  502.4.8 Cis-RuBr2(TM5.0)4  512.4.9 Trans-RuBr2(TMSG)4 ^  512.4.10 Ru2C15(Et2S0)4  512.4.11 [H(nPr2SQ)2]+[trans-RuC14(nPr250)2]- ^ 522.4.12 Ru2C15(nPr2S0)5 ^  532.4.13 Ru2C15(nBu2S0)5  542.4.14 [RuC12(MePhS0)2]n ^  542.4.15 RuC13(Ph2S0)2 and mer-RuC13(Ph2S0)2(CH3OH)^552.5 The Synthesis of the Chelating Sulfoxide Complexes of Ruthenium^562.5.1 Trans-RuC12(BMSE)2 ^  562.5.2 Cis-RuC12(BESE)2  572.5.3 Trans-RuC12(BPSE)2 ^  572.5.4 Cis-RuC12(BMSP)2  58Chapter 3: The Structural Properties of Sulfoxides; RutheniumComplexes of DMSO and TMSO ^  593.1 General Introduction ^  593.2 Structural Properties of Sulfoxides ^  603.3 Sulfoxide-Metal Bonding ^  613.3.1 S-Bonded Sulfoxide-Metal Complexes ^ 623.3.2 0-bonded Sulfoxide-Metal Complexes  63vii3.4 A Bonding Model for Sulfoxide-Metal Complexes ^ 643.5 Electronic and Steric Effects ^  673.6 NMR and IR Spectroscopy  683.6.1 1H NMR and 13C NMR Spectroscopy ^ 683.6.2 Infrared Spectroscopy ^  703.7 Monodentate Sulfoxide Complexes of Ru(II) and Ru(III) ^ 723.8 DMSO Complexes of Ruthenium ^  743.8.1 Cis-RuX2(DMS0)4, X = Cl or Br ^ 763.8.1(a) Cis-RuC12(DMS0)3(DMSQ)  763.8.1(b) Cis-RuBr2(DM50)3(DMSD) ^ 783.8.2 Trans-RuX2(DMS0)4, X = Cl, Br or I  793.8.2(a) Trans-RuC12(DMS0)4 ^  793.8.2(b) Trans-RuBr2(DMS0)4  813.8.2(c) RuI2(DMS0)4 ^  813.8.3 The Crystal Structures of RuX2(DMS0)4 Complexes, X= Cl or Br ^  823.8.3(a) Cis-RuC12(DMS0)4 and cis-RuBr2(DMS0)4^823.8.3(b) Trans-RuC12(DM50)4 and trans-RuBr2(DMS,0)4 ^  833.8.4 The Geometry of the DMSO Ligands Within theRuX2(DMS0)4 Complexes, X = Cl or Br ^ 853.8.5 Ru2C14(DMS0)5 ^  87viii3.8.6 Ru2C16(DMS0)4 ^  913.9 TMSO Complexes of Ru(II)  943.9.1 Cis-RuX2(TMS0)4, X = Cl or Br ^ 943.9.1(a) The Synthetic and Spectroscopic details for cis-RuC12(TMS0)4 ^  943.9.1(b) The Synthetic and Spectroscopic details for cis-RUBr2(TM5.0)4 ^  1013.9.2 The Crystal Structures of cis-RuC12(TMS0)4, form aand form b ^  1023.9.3 Trans-RuX2(TMS0)4, X = Cl or Br ^ 1053.9.3(a) Trans-RuC12(TMS0)4  1053.9.3(b) Trans-RuBr2(TM5.0)4 ^  1073.9.4 The Crystal Structure of trans-RuBr2(TMS0)4 ^ 1093.9.5 [RuBr3(TMS0)4Lib ^  1113.9.6 The Crystal Structure of [RuBr3(TMS0)4Li]2 ^ 1133.9.7 The Geometry of the TMSO Ligands Within the Ru(II)Complexes ^  1183.10 Other Related Ru Reactions Involving DMSO or TMSO ^ 1203.10.1 Related Reactions Involving DMSO ^ 1203.10.2 Related Reactions Involving TMSO  1233.10.3 Ru-Thioether Complexes from Reactions with DMSOand TMSO ^  124ixChapter 4: Sulfoxide Complexes of Ruthenium Other Than Those ofDMSO and TMSO: Other Monodentate and Bidentate SulfoxideLigand Systems ^  1264.1 Introduction  1264.2 Monodentate Sulfoxide Complexes of Ruthenium ^ 1264.2.1 Ru2C15(Et2S0)4 ^  1264.2.2 [H(nPr2SQ)2]+[trans-RuC14(nPr2S0)2]- ^ 1314.2.3 The Crystal Structure of [H(nPr2SD_)2]-4- [trans-RuC14(nPr250)2I ^  1334.2.4 Ru2C15(nPr2S0)5  1404.2.5 Ru2C15(nBu2S0)5 ^  1424.2.6 [RuC12(MePhS0)2]n  1444.2.7 RuC13(Ph2S0)2 and mer-RuC13(Ph2S0)2(Me0H) ^ 1464.2.8 The Crystal Structure of mer-RuC13(Ph2S0)(Ph2SQ.)(Me0H) ^  1484.3 Chelating Sulfoxide Complexes of Ruthenium  1524.3.1 Trans-RuCl2(BMSE)2 ^  1544.3.2 Cis-RuC12(BESE)2  1554.3.3 Trans-RuC12(BPSE)2 ^  1584.3.4 The Crystal Structures of theRuC12[RS(0)(CH2)2S(0)% complexes, R = Me, Etand nPr ^  160x4.3.5 Cis-RuC12(BMSP)2 ^  1624.3.6 The Crystal Structure of cis-RuC12(BMSP)2 ^ 164Chapter 5: The Assessment of Selected Biological Properties ofRuthenium Sulfoxide Complexes ^  1665.1 Introduction ^  1665.2 The Ruthenium Sulfoxide Complexes Studied ^ 1675.3 The Biological Activity of Ruthenium Sulfoxides in CHO Cells . . ^ 1685.3.1 Whole Cell Accumulation under Air or N2 ^ 1685.3.2 Complex Accumulation in Cells after Four Hours UnderAir or N2 ^  1685.3.3 Accumulation Profiles of Selected Ruthenium Sulfoxides . 1695.3.3(a) Common Features in the Accumulation Profiles . 1715.3.3(b) Individual Features in the AccumulationProfiles ^  1715.3.4 Accumulation of Ru in Cell Nuclei ^ 1745.3.5 The Interactions of Ru-Sulfoxide Complexes with DNA . ^ 1755.3.5(a) The Damaged DNA Precipitation Assay ^ 1755.3.5(b) Binding to DNA in Whole Cells ^ 1765.3.6 The Toxicity of Ruthenium Sulfoxides in CHO Cells . . . ^ 1775.3.7 The Partition Coefficients of Ru-sulfoxide Complexes . . ^ 1775.4 The Implications of the Biological Results ^  178xiM5.5 Methodology ^  181M5.5.1 Cell Culture Procedures ^  181M5.5.2 Cell Incubation Procedures  182M5.5.3 Cell Accumulation Studies ^  184M5.5.4 Atomic Absorption Spectroscopy  184M5.5.5 The Isolation of Nuclei from Whole CHO Cells ^ 185M5.5.6 An Outline of the Damaged DNA Precipitation Assay . 186M5.5.7 The Isolation of Cellular DNA from Whole CHO Cells^186M5.5.8 Cell Toxicity Under Aerobic and Hypoxic Conditions .^187M5.5.9 Partition Coefficients ^  188Chapter 6: Conclusions and Recommendations For Future Work ^ 1906.1 The Evolution of the Project: From Ir to Ru ^ 1906.2 Ru Complexes of DMSO and TMSO  1916.3 Monodentate Sulfoxide Complexes of Ru(II) and Ru(III) (OtherThan Those of DMSO and TMSO) ^  1926.4 Bidentate Sulfoxide Complexes of Ru(II)  1936.5 The Cellular Accumulation of Selected Ruthenium-SulfoxideComplexes in CHO Cells ^  1946.6 Suggestions for Future Work  195References ^  198xiiAppendix A: Methods and Materials for Biological Experiments ^ 213A-1 Preparation of Stock Solutions ^  213A-1(a) a Media ^  213A-1(b) Phosphate Buffer Saline Solutions ^ 213A-1(c) Methylene-Blue Solution ^  214A-1(d) "EDTA" Solution ^  214A-1(e) Trizma Buffers (Tris-HC1 Solutions) ^ 214A-1(f) Tris-EDTA (TE) Solutions ^  214A-1(g) TNE Solutions ^  215A-1(h) TNE-Equilibrated Phenol ^  215A-1(i) HEPES ^  215A-2 Atomic Absorption Standards ^  216A-3 Sampling Conditions ^  216A-4 Furnace Parameters  216A-5 The Damaged DNA Precipitation Assay ^  217A-5(a) Preparation of DNA Cellulose  217A-5(b) The Isolation of the HMG Proteins ^ 217A-5(c) The Damaged DNA-Affinity Precipitation Assay ^ 219A-5(d) Gel Electrophoresis ^  219Appendix B: Accumulation Profiles for Selected Ruthenium SulfoxideComplexes ^  220Appendix C: Toxicity Data for Selected Ruthenium Sulfoxide Complexes . . 223Appendix D: Experimental Details, Final Atomic Coordinates, BondLengths and Angles for the Crystal Structures ^ 226D-1 Crystal Data and Results for cis-RuC12(TM50)4, form a ^ 226D-2 Crystal Data and Results for cis-RuC12(TMa0)4, form ^ 226D-3 Crystal Data and Results for [RuBr3(TMS0)4Li]2 ^ 226D-4 Crystal Data and Results for trans-RuBr2(TMS0)4 ^ 227D-5 Crystal Data and Results for [H(nPr2SQ)2]+[trans-RuC14(nPr2a0)2] ^  232D-6 Crystal Data and Results for RuC13(Ph2S0)2(Me0H) ^ 238D-7 Crystal Data and Results for trans-RuC12(BMSE)2 ^ 245D-8 Crystal Data and Results for cis-RuC12(BESE)2  252D-9 Crystal Data and Results for trans-RuC12(BPSE)2 ^ 261D-10 Crystal Data and Results for cis-RuC12(BMSP)2 ^ 267Appendix E: Unresolved Reactions ^  273E-1 Introduction  273E-2 Reactions of IrC13 with Nitroimidazoles ^ 273E-3 The Reaction of cis-RuC12(DMS0)4 with 2-amino-5-nitrothiazole (ANT) ^  275E-4 The Reaction of cis-RuC12(TMS0)4 with SR 2508 ^ 275xivE-4(a) Data for RuC12(TMS0)2(SR 2508).2(H20) . . . . 276E-5 The Reactions of BMSB and BESB with the "Ruthenium-Blue" Solutions ^  277E-6 The Reaction of 4-Nitroimidazole with the Ru Complexesof Chelating Sulfoxides ^  277List of TablesTable 3.1 Selected Bond Lengths for DMSO in the Solid and Gas Phase . . . . 61Table 3.2 Some Structural Data for Selected Transition Metal-DMSOComplexes ^  63Table 3.3 The SO Stretching Frequencies of Some 0- and S-Bonded Ru-Sulfoxide Complexes ^  71Table 3.4 Examples of Ruthenium-Sulfoxide Complexes Reported in theLiterature and From this Present Work^  75Table 3.5 Selected Bond Lengths for the RuX2(DMS0)4 Systems ^ 84Table 3.6 Selected Bond Angles for the DMSO Complexes ^ 86Table 3.7 Selected Bond Lengths and Angles for cis-RuC12(TMS0)4, form a;published in ref. 171(a) ^  103Table 3.8 Selected Bond Lengths and Angles for cis-RuC12(TMS0)4, form a;Published in ref. 171(a) ^  105Table 3.9 Selected Bond Lengths and Angles for trans-RuBr2(sulfoxide)4,sulfoxide = DMSO or TMSO ^  111Table 3.10 Selected Bond Lengths and Angles for [RuBr3(TMS0)4Li]2 ^ 115Table 3.11 Selected Bond Angles for the TMSO Ligands Within the Ru(II)Complexes ^  119Table 4.1 Selected Bond Lengths and Angles for [H(nPr2SQ)2][trans-RuC14(nPr2S0)2] ^  133Table 4.2 Selected Bond lengths for Some Sulfoxide and ThioetherxviComplexes of Rua° and Ru(III) ^  137Table 4.3 Selected Bond Lengths and Angles for mer-RuC13(Ph2S0)(Ph2SQ)(MeDH) ^  150Table 4.4 Selected Bond Lengths and Angles for trans-RuC12(BMSE)2, cis-RuC12(BESE)2 and trans-RuC12(BPSE)2 ^  161Table 4.5 Selected Bond Lengths and Angles for cis-RuC12(BMSP)2 ^ 164Table 5.1 Ru Sulfoxide Complexes Studied In Vitro ^  167Table 5.2 Summary of Biological Results From the Various Assays ^ 179Table A.1 Furnace Parameters used in AAS ^  217xviiList of FiguresFigure 1.1 The radiosensitization of cells by oxygen (adapted from ref. 14(b)) . 6Figure 1.2 Examples of some nitroimidazoles that have been developed   15Figure 1.3 The structures of some second generation Pt complexes and somerecent (*) examples taken from ref. 72 ^  22Figure 1.4 The structures of the Co/DCE/BCE complexes used by Ware etal. (adapted from ref. 83(a) & (b)) ^  25Figure 1.5 Examples of non-platinum metal complexes with reported anti-tumour activity ^  28Figure 1.6 Some examples of chiral sulfoxides used in catalytic asymmetrichydrogenation studies ^  31Figure 3.1 The structure of DMSO  60Figure 3.2 The three resonance forms for sulfoxides ^  65Figure 3.3 Chirality within sulfoxides ^  73Figure 3.4 Diagram of cis-RuC12(DMS0)4 showing the numbering scheme;adapted from ref. 124 ^  83Figure 3.5 A stereoview of trans-RuC12(DMS0)4; taken from ref. 121 ^ 85Figure 3.6 HETCOR 2D array for TMSO in CD2C12 ^  97Figure 3.7 HETCOR 2D array for RuC12(TMS0)4 in CD2C12 ^ 100Figure 3.8 A stereoview of cis-RuC12(TMS0)4, form a; taken from ref.171(a) ^  104Figure 3.9 A stereoview of trans-RuBr2(TMS0)4 showing 50% probabilityxviiithermal ellipsoids for the non-hydrogen atoms ^  110Figure 3.10 An ORTEP plot of [RuBr3(TMS0)4Li]2  114Figure 4.1 An ORTEP plot for the complex [H(nPr2SQ)2][trans-RuC14(nPr20)2] ^  134Figure 4.2 A stereoview for RuC13(Ph250)(Ph2SQ)(MeQH) showing 50%probability thermal ellipsoids for the non-hydrogen atoms ^ 149Figure 4.3 A stereoview of trans-RuC12(BMSE)2 showing 50% probabilitythermal ellipsoids for the non-hydrogen atoms ^  155Figure 4.4 A stereoview of cis-RuC12(BESE)2 showing 50% probabilitythermal ellipsoids for the non-hydrogen atoms ^  156Figure 4.5 A stereoview of trans-RuC12(BPSE)2 showing 50% probabilitythermal ellipsoids for the non-hydrogen atoms ^  158Figure 4.6 A stereoview of cis-RuC12(BMSP)2 showing 50% probabilitythermal ellipsoids for the non-hydrogen atoms ^  163Figure 5.1 Whole cell accumulation of Ru-sulfoxides in CHO cells at 4 h; theamounts of Ru is expressed as ng/106 cells (+ 10%) ^ 170Figure 5.2 Accumulation of cis-RuC12(BESE)2 (5) at 0.50 mM in CHO cells^172Figure 5.3 Accumulation of trans-RuC12(BPSE)2 (6) at 0.50 mM in CHOcells   173Figure 5.4 The toxicity of cis-RuC12(BMSP)2 (7) at 1.0 mM, PE vs. Time . . . 178Figure 5.5 Diagram of the modified Erlenmeyer flask used for theaccumulation and toxicity experiments ^  183xixFigure B.1 Accumulation of cis-RuC12(DMS0)4 (1) at 1.0 mM in CHO cells . 220Figure B.2 Accumulation of trans-RuC12(DMS0)4 (2) at 1.0 mM in CHOcells   220Figure B.3 Accumulation of cis-RuC12(TMa0)2 (3) at 1.0 mM in CHO cells . 221Figure 8.4 Accumulation of trans-RuC12(BMSE)2 (4) at 1.0 mM in CHOcells   221Figure B.5 Accumulation of cis-RuC12(BMSP)2 (7) at 1.0 mM in CHO cells . . 222Figure C.1 The toxicity of cis-RuC12(DMS0)4 (1) at 1.0 mM, PE vs. Time . . 223Figure C.2 The toxicity of trans-RuC12(DM5.0)4 (2) at 1.0 mM, PE vs.Time   223Figure C.3 The toxicity of cis-RuC12(TMa0)4 (3) at 1.0 mM, PE vs. Time . . 224Figure C.4 The toxicity of trans-RuC12(BMSE)2 (4) at 1.0 mM, PE vs. Time . 224Figure C.5 The toxicity of cis-RuC12(BESE)2 (5) at 0.50 mM, PE vs. Time . . 225Figure C.6 The toxicity of trans-RuC12(BPSE)2 (6) at 0.50 mM, PE vs.Time ^  225XXList of SchemesScheme 1.1 The radiosensitization of DNA by oxygen; other compounds thatmimic the action of 02 may also radiosensitize DNA ^ 8Scheme 1.2 The radioprotection of DNA by NPSH groups  10xxiList of AbbreviationsThe following list of abbreviations, most of which are commonly used in thechemical and biological literature, will be employed in this thesis:2D^ 2-Dimensional (NMR)A Angstrom (10-8 cm)13c{ 1H}^13C nuclear magnetic resonance (proton decoupled)1H NMR Proton nuclear magnetic resonanceAAS^ Atomic absorption spectroscopyBCE N,N'-bis(2-chloroethyl)ethylenediamineBDIOS^(2R,3R)-2,3-0-isopropylidene-2,3-dihydroxy-1,4-bis(benzylsulfinyl)butaneBESB^ 1,4-bis(ethylsulfinyl)butaneBMSB 1,4-bis(methylsulfinyl)butaneBESE^ 1,2-bis(ethylsulfinyl)ethaneBMSE 1,2-bis(methylsulfinyl)ethaneBPSE^ 1,2-bis(propylsulfinyl)ethanebr Broad (NMR and IR)BSO^ Buthionine sulfoximineCHO Chinese hamster ovary (a cell line)DCE^ N,N-bis(2-chloroethyl)ethylenediamineDIOS (2R,3R)-2,3-0-isopropylidene-2,3-dihydroxy-1,4-bis(methylsulfinyl)butaneDDIOS^(2R,3R)-2,3-dihydroxy-1,4-bis(methylsulfinyl)butanedGMP 2'-deoxyguanosine monophosphateDIOP^ (2R ,3R) or (2S ,3S)-0-isopropylidene-2 ,3-dihydroxy-1,4-bis(diphenylphosphino)butaneDMS^ DimethylsulfideDMSO Dimethylsulkoddedt^ Doublet of triplets (NMR)D'TT DithiothreitolEl^ Electron impact (mass spectroscopy)ESR Electron spin resonance spectroscopyFAB^ Fast atom bombardment (mass spectroscopy)fac FacialHour(s)HEPES^N-2-hydroxyethylpiperazine-N'-2-ethane sulfonic acidHETCOR Heteroatom correlation spectroscopyHMG^ High mobility groupICR Imidazolium tetrachlorobis(imidazole)ruthenate(III)IR^ InfraredMultiplet (NMR)mer MeridionalMHz^ Megahertz (106 Hertz)min Minute(s)mL^ MillilitremM Millimoles/Litreng^ Nanogram (10-9 gram)nm Nanometre (le metre)NPSH^Non-protein sulfhydryl groups0 (with sulfoxide^Oxygen-bondedligands)OD^ Optical densityOER Oxygen enhancement ratioPartition coefficientPBS^ Phosphate-buffered salinePE Plating efficiencyPMSF^Phenyl methyl sulfonyl fluoridePNAP Para-nitroacetophenoneppm^ Parts per million (NMR)qn Quintet (NMR)qt^ Quartet (NMR)rpm Revolutions per minuteRSH^ Sulfhydryl compoundRSSR Dithiol compoundS (with sulfoxide^Sulfur-bondedligands)s^ Singlet (NMR)SDS Sodium dodecylsulfateSER^ Sensitizer enhancement ratiot Triplet (NMR)td^ Triplet of doublets (NMR)TE Tris-EDTA solutions consisting of EDTA and Tris-HclTMS^ Tetramethylene sulfideTMSO Tetramethylene sulfoxideTNE^ Solution consisting of Tris-Hcl, NaCl and EDTATris-Hcl Trizma buffers made from Trizma-HclUV-Vis^Ultraviolet-Visiblee Extinction coefficientAm^ Molar Conductivity14 Descriptor for bridgingAeff^ Magnetic momentAL Microlitre (10-6 litre)gm Micrometre (10-6 metre)v^ Frequency (cm-1)xxivAcknowledgementsMy gratitude and thanks go to both my supervisors (in equal portions!), Profs.Brian James and ICirsten Skov, for their guidance, encouragement and patience duringthe course of the work and the completion of this thesis.I am indebted to my parents and sister for their support and encouragement andfor never saying "Get a real job!" once in the last 51/2 years.The support staff in the chemistry department (especially Peter Borda, SteveRak, Marietta Austria and Lianne Diarge) are gratefully acknowledged for their help.Special thanks go to Dr. S. J. Rettig for the many crystal structures he solved whichwere indispensable in resolving some of the formulations in this thesis.The "Heavy Metals" in the Dept. of Medical Biophysics: Thank you Dr. BrianMarples (Wordperfect rules!) for help with the HMGs, Haibo Zhou and Susan MacPhailfor help with those exasperating cells, Hans Adomat for literally everything (especiallythe flooding (*@%#!!) AA machine) and Jeff Matthews for finding humour amidst thedebris of many a dead experiment.The joint-students: help from Grant Meng and "processing (read: whining)" tea-time sessions with Jeff Posakony is greatly appreciated. In particular, JamesRavensbergen is thanked for agreeing (and then not complaining!) to help with the 16vessel experiments.Its a FACT! Past and present members of the Brian James group are thanked fortheir help in lab matters and silly discussions (Ajey, Ken, Richard and Deryn). Dr. J.Jaswal, in particular, is thanked for his invaluable contributions and work.Kevin, Helen (great wedding!), Ivan and Oliver are gratefully acknowledged forhelp with computer type things to do with the thesis and the occasional meal at month'send.A special thank you to other friends who reminded me that life also existed(however briefly) outside the big "T": Chris and Chris - It was a privilege to be yourbuffer. Foon Yip for "SO!..", Chris Gray for Sanctuary, Sheri Little for the Chair,Natalie Lazeroff for regular coffee, Jihan Marjan for her optimism, Mike Blower forBrowns Bay, Mike Berendt for showing up in the nick of time, Dr. Patrick Paglia forreality checks, Tim Fijal for new found perspective and James Brace the solicitor for"gleaned" (p.180) and the boring anecdote of the day. MK, Dr. JA and KB: I done it.KTK (seule, perdue, abandonnee...}161as! [ta] fatale beautd) - Merci encore.Final words: "smoking on the night train, chewing on a jelly roll" - that's it.I'm out of here.XXVChapter 1: General Introduction1.1 PreambleDue to the interdisciplinary nature of this project, it is useful to outline brieflythe layout of this introductory chapter. The material in this chapter is divided into twoparts; the first discusses various aspects of cancer, modes of treatment and problemsassociated with the treatments (Sections 1.2 - 1.10.3). In particular, hypoxia, which isa factor in the failure of treatments to control the disease at the site of the tumour, willbe discussed in some detail (Section 1.4). This in turn leads to the second part of thischapter, the potential that metal complexes may have for the control of the problemsassociated with the treatments (Section 1.11). A brief review of some of the transitionmetal based anti-cancer agents that are currently being used or investigated is presented(Sections 1.12 and 1.14). The initial aim of this Ph.D project was to synthesizenitroimidazole complexes of Jr for imaging, but the project evolved to its present formfrom work done in following up a sideline of a previous project in this interdisciplinaryfield (see Section 1.15).1.2 CancerCancer occurs in many forms depending on the part of the body and the type ofcells involved. For example, most tumours occur as a localized grouping of cancerouscells, while in others like leukaemia, the malignant cells are widely dispersed in theblood stream [1]. Regardless of the type of cancer, however, cancer cells share onecommon characteristic - they grow in an uncontrolled and random manner and can1spread to other parts of the body. The unchecked growth of these cells eventuallyinterferes with other organ functions in the body causing pain and, eventually, collapseof the entire organism [2].Unlike other diseases where the renegade agent causing the disease is a "foreigninvader" (viruses, bacteria, parasites), the malignant cells in cancer are usually derivedfrom the host and thus are not recognized as foreign by the body's immune system. Thisleads to a particular problem in treatment of cancer because most other diseases arecontrolled by targeting the invader and taking advantage of some difference that existsbetween the host's cells and those of the invader. In other words, some degree ofselectivity is usually present which can be exploited therapeutically to aid the body'simmune system to recognize and/or kill the foreign substance. Such selectivity is notfound in cancer and the immune system does not discriminate between the malignantand normal cell. This lack of selectivity means that most forms of treatment do notdistinguish between normal and malignant cells either, and in many cases induce damageto normal tissue that outweighs the therapeutic benefits of the treatment [3].Hypoxia, which results from the rapid growth and poor vasculature of thetumour, is another problem in the treatment of cancer (see Section 1.4) although someattempt is now being made to take advantage of the hypoxic environment (see Sections1.10.2 and 1.10.3).1.3 TreatmentsThe three major treatment modalities for cancers are surgery, chemotherapy and2radiotherapy. In most cases, depending on the site and type of disease, somecombination of the three is used in a concerted effort to cure the patient. These threemain modes of treatment will be discussed very briefly here.(a) The purpose of surgery is to remove the malignant tissue but is only of usewhen the tumour is well defined and accessible. Unfortunately, surgery is of limited useagainst disseminated cancers which occur in about 30% of patients diagnosed with aninvasive cancer [1](b) Chemotherapy uses drugs to recognize and remove undesirable invadingorganisms without harming the host system. This implies the ability to differentiatebetween "good" and "bad" cells on the part of the drug and to exploit any such existingdifference to disable invading organisms. Unfortunately, complete differentiationbetween normal and malignant cells in cancer is not always achievable, and the side-effects of the drug used can outweigh the benefits.(c) In radiotherapy, ionizing radiation is used to kill tumour cells; this isprobably the most widely used form of treatment with almost 50% of new cancerpatients in North America receiving radiotherapy as part of their treatment [4].Radiotherapy is useful in the treatment of localized tumours and in the treatment ofHodgkin's disease but is of limited use in situations where the tumour is eitherradioresistant or surrounded by normal tissue which is radiosensitive. In such cases, itmay prove impossible to deliver the required curative dose of radiation without inducingunacceptable damage to normal tissue [5].31.4 Hypoxia - Definition and ProblemsHypoxia may be defined generally as the condition where areas of tissue havea low oxygen contentl relative to surrounding tissue. Tumours were proposed in 1955to contain areas of hypoxia that are generally further than 150-200 Am away from thevascular system [6]; such areas can constitute up to 30% of the tumour by mass [7].These areas occur because of the inability of the vascular system, which is responsiblefor the delivery of oxygen to living tissue, to keep up with the random and sometimesrapid growth of the tumour. The result is an oxygen gradient that, due to the normalmetabolic requirement of the cells, renders the cells farthest away hypoxic,radioresistant and sometimes resistant to chemotherapy [8,9].While conditions of hypoxia lead to the cessation of cell division, these cells arestill viable and capable of recommencing growth upon reoxygenation [10]. As aresult, when the oxygenated areas of the tumour are removed by radiotherapy, thehypoxic areas, being radioresistant and not having suffered as much damage, becomereoxygenated and recommence their growth cycle leading to regeneration of the tumour.The problem of hypoxia is a complex one, and agents that can work alone (e.g.hypoxic cytotoxins, see Section 1.10.2) or in combination with other modalities (e.g.radiation and radiosensitizers, see Section 1.9.2) are needed to remove such areas. Thusthe detection and the definition of such hypoxic areas (e.g. by imaging withradioisotopes, see Section 1.10.3) can be important in order to optimize treatments.1 The term "oxygen" is used throughout in place of the more correct "dioxygen" formolecular 02.41.5 Radiation and the Oxygen EffectFor the purposes of this introduction, only ionizing radiation and its effects onbiological systems are considered. Ionizing radiation is radiation that is energetic enoughto cause ionizations and electronic excitations in the molecule with which it interacts.In radiobiology, the target of radiation is DNA and the desired end point is irreparabledamage to DNA so that replication is impossible.The interactions between radiation and DNA can occur either directly orindirectly. In the former case, DNA is ionized as a result of a direct "hit" (energytransferred to DNA directly from radiation), while in the latter case DNA is ionized byinteraction with some other molecule that has been ionized by radiation (e.g. .0H fromthe radiolysis of H20) [11].Regardless of the way in which DNA interacts with radiation, oxygenated cellsare known to be more sensitive to the damaging effects of radiation than hypoxic cells.This phenomenon was first observed in the 1920s [12] and is now well established.The effect of oxygen on radiation damage is a general one and can be extended to mostbiological manifestations of damage, such as DNA strand breaks, gene mutation orchromosomal abberations [13].The degree of sensitization due to oxygen can be quantified using the OxygenEnhancement Ratio (OER) which is defined as the ratio of radiation doses required toachieve the same end-point in the absence and presence of oxygen [13] (see eq. 1.1).Dose in NitrogenOER — ^ (1.1)Dose in Oxygen5Figure 1.1 shows typical response curves for the survival of Chinese HamsterOvary (CHO) cells that have been irradiated by X-rays in air-saturated medium and inmedium that has been purged of air by an active flow of N 2 . The absence of oxygenhas a dramatic radioprotective effect as higher doses of radiation are required to achievethe same end-point as the aerobic sample. Typically the OER for mammalian cells isabout three at an endpoint of 1% survival [14].The implications of such a high OER are profound for radiotherapy becauseFigure 1.1 The radiosensitization of cells by oxygen (adapted from ref. 14(b))6three times the amount of radiation required to kill oxygenated cells would be neededto kill the hypoxic fraction. Thus with clinical doses of radiation, the proportion of cellswhich are hypoxic will survive treatment by radiotherapy, reoxygenate, repair andrepopulate, thus leading to regeneration of the tumour.In direct action, DNA is the immediate target for radiation and is initiallyionized before forming a highly reactive radical; other chemical processes can repairDNA and compete with radical formation [11].RH + X-ray -0, R + H' (-1. RH; via repair) (1.2)Oxygen can compete with the repair processes and "fix" (make permanent) the initialdamage caused by radiation in two ways. In the first case, the radical reacts withoxygen in an irreversible manner to give an organic peroxide [15] (eq. 1.3)R. + 02 --0 R02. (1.3)Repair mechanisms that can reverse the process shown in eq. 1.2 are thwarted, andoxygen is said to "fix" the lesion caused by radiation or to have caused permanentdamage to DNA. In the absence of 02, the chances of organic peroxides forming arelower so radiation induced lesions are more likely to undergo repair.In the second mechanism (shown in Scheme 1.1), the ionized electron migratesand is localized on an area of high electron affinity. In the presence of another molecule(such as 02 or a radiosensitizer) with a higher electron affinity, electron transfer takesplace. The chance of charge recombination processes, that would restore the DNA toits original form, is reduced and the chances of decay of the now positive molecule toa radical, which can then undergo some irreversible reaction to "fix" the original lesionon the target, are increased [16]. Sulfhydryl (SH) compounds present in the cell can,7cp.00)rRSHR •S1/2 RS-SRI radicaldecomposesgo\damaged DNARSH = Sulfhydryl compoundionizationEmEauwassep-electron migrationH donation 02 022electronabstractionDNAhowever, repair DNA chemically by donation of a hydrogen atom (see Section 1.6 andScheme 1.1).Scheme 1.1 The radiosensitization of DNA by oxygen; other compounds that mimic theaction of 02 may also radiosensitize DNAIndirect action is estimated to cause 60% of radiation induced damage on DNA(in air) [17]. As water is by far the largest component of cells by volume, itsradiolysis products play an important role in the effects of indirect action. The first twosteps in the radiolysis of water are (a) ionization of water to produce an electron (eq.1.4) and (b) excitation of water which then decomposes to form the radical speciesshown in equation 1.5.H20 -0 I-120+ + e-^ (1.4)8H20 -01120* -0 H. + *OH^ (1.5)The .0H radical is the most reactive species produced and can induce lesions inDNA by H-abstraction (eq. 1.6). The damage can then be made permanent by chemicalreaction or by interaction with oxygen as described in the previous section, i.e. theformation of an organic peroxide (eq. 1.3).RH + *OH -4. R* + H20^ (1.6)In the presence of oxygen the electron reacts with oxygen to form the superoxideanion radical [18] as shown below:c(ac) +02 --a. 02".^ (1.7)The superoxide radical is reactive and dangerous as it can cause damage to othercellular components including proteins, lipids and nucleotides [19].In these ways then, oxygen enhances the lethal effects of radiation by "fixing"damage incurred through direct action and competing with repair processes that wouldotherwise restore the target to its original condition. In indirect action, oxygen reactswith the primary radiolysis products to form the superoxide radical which is capable ofdamaging cellular components. In hypoxic areas, the absence or lower levels of oxygenprotects the cells from radiation damage. Less damage is made permanent by oxygenand, as there is less competition with repair processes, more lesions can be repaired.1.6 Sulfhydryl Compounds as RadioprotectorsSulfhydryl (SH containing) compounds present in the cell are thought toradioprotect in two ways; the two proposed models [20,21] are complementaryexcept, that in one model, damaged DNA is repaired, while in the second indirect9damage to DNA is prevented.(a) Donation of a hydrogen atom from a sulfhydryl compound (RSH) to the freeradical on DNA caused by interaction with radiation (see Scheme 1.1) prevents thedecomposition of the radical and repairs the chemical lesion [20] (see Scheme 1.2). Thethiol radical RS. then recombines to form the oxidized dithiol species (RSSR).(b) Alternatively, the proton is donated to organic free radicals that are producedduring irradiation; these free radicals are thus "neutralized" and can no longer damageDNA indirectly [21] (See Section 1.5 and Scheme 1.2).DNA radicalK)o.00) X-ray  DNA^ RSH1/2 RS-SRX-raywesammatea.a.— R • ^ R HRSH RS •RSH Sulfhydryl compound^1/2 RS-SRR Organic compound in cellScheme 1.2 The radioprotection of DNA by NPSH groupsThe radiosensitizing ability of some compounds may be due to the depletion ofsuch non-protein sulfhydryl (NPSH) or thiol groups which would otherwise have aradioprotective effect in the cell [22]. An example of such a compound is buthioninesulfoximine (BSO) which inhibits the synthesis of glutathione in the cell thus enhancingradiosensitivity [23]. Nitroimidazoles such as misonidazole and metronidazole (seeSection 1.9.2) may also radiosensitize cells by binding to and removing intracellular10NPSH [24].1.7 Overcoming the Problem of Hypoxic CellsThere are several approaches to dealing with the problem of hypoxia. Onesolution is to increase the levels of oxygen present in the tumour cell, for example,through the use of hyperbaric oxygen treatments where the patient is treated withradiation in an oxygen enhanced atmosphere. However, oxygen toxicity and increasedsensitization of normal tissue were sometimes problems in the treatment. In addition,the levels of oxygen within the tumour were not necessarily increased due to theinadequate vascular system found in most tumours [25].The use of radiation sources with a higher ionizing density (e.g. neutron beams,negative pi-mesons and accelerated heavy atoms [2]) can compensate for theradioresistance of hypoxic cells by causing more damage to DNA through direct ratherthan indirect action (see Section 1.5); for example, when the radiation source is changedfrom X-rays to neutrons, the OER decreases from 3 to 2 [26].The use of chemical agents, either as a supplement to radiotherapy or as anti-cancer agents themselves, has great potential in the control of hypoxic areas in tumoursand is discussed in Section ChemotherapyIn its broadest sense, chemotherapy uses drugs to alleviate either the symptomsor causes of a disease. In the context of this introductory chapter, chemotherapeutic11agents may be divided into two categories: drugs used as adjuvants to radiotherapy ordrugs used as a separate form of treatment themselves.Certain compounds (generally known as chemical radiosensitizers, see Section1.9) can be used in conjunction with radiotherapy to "fix" damage on DNA caused bythe indirect action of radiation in a manner similar to oxygen, or to prevent chemicalrepair processes from occurring (e.g. by depleting the cell of sulfhydryl compounds, seeSection 1.6).Other chemotherapeutic agents have been designed with the aim of binding toDNA or other cell proteins in order to inhibit replication and/or other cell processesvital for cell life (see Section 1.10). Such agents often show some selectivity for rapidlydividing cells (e.g. tumour cells) which may not be able to repair damage on their DNAbefore replication. Other compounds have been designed to take advantage of thehypoxic environment to trigger the "action" of the complex (e.g. the release of cytotoxicligands coordinated to transition metals by reduction of the metal centre in hypoxia (seeSection 1.11.5)).1.9 Chemical RadiosensitizersA radiosensitizer is a compound that sensitizes cells to radiation damage. Themore useful agents would be selective to hypoxic cells, and as such be potentially usefulin overcoming the problem of hypoxia in radiotherapy. With the use of chemicalcompounds that mimic the radiation sensitizing properties of oxygen, the drug could besynthetically tailored to have specific characteristics. The compound must be effective12at clinically achievable concentrations and have an effect at clinically relevant doses ofradiation (2 Gy). The Sensitizer Enhancement Ratio (SER), defined as the ratio ofradiation doses required for a specified endpoint in the presence and absence of thedrug, does not need to be as large as the OER. However, the compound would ideallydifferentiate between normal and hypoxic tissue and be able to penetrate the tumour,which implies the ability to cross cellular membranes. The drug must be resistant tonormal metabolic processes so that it can reach the hypoxic cells without beingconsumed along the way. Finally, any side-effects and the toxicity of the drug must bekept within tolerable limits while still conferring a useful degree of sensitization[27,28].1.9.1 Hypoxic Cell SensitizersThe search for compounds that have potential as hypoxic cell sensitizers hasfocused primarily on those that can mimic the sensitizing action of oxygen by acceptingelectrons. It is not surprising then that the largest class of compounds that have thisquality are the so-called "electron-affinic" compounds [28]. The compounds containedwithin this class include among others di- and aromatic ketones, quinones and diesters,but they all have electron accepting groups as part of their structure [29,30].Initially, these compounds were tested, with encouraging results, on micro-organisms [31,32] (bacteria and bacterial spores) in vitro2 as hypoxic sensitizers,2 The terms in vitro and in vivo are used throughout this thesis work to indicateexperiments done with cells and in animal studies, respectively.13and reports on the hypoxic sensitizing ability of p-nitroacetophenone (PNAP) onmammalian cells (CHO) in vitro appeared in 1971 [33]. Unfortunately, the samesensitization could not be duplicated in vivo due to the insolubility of the compound.Subsequent to this report, various nitrofurans were reported to sensitize hypoxicmammalian cells in vitro [34]; this was exciting as nitrofurans were already in clinicaluse as antibacterial agents. Unfortunately, in vivo activity was generally disappointingdue to the toxicity of the compounds at the levels required for sensitization, and so thesecompounds fell out of favour as sensitizers. One other factor thought to be responsiblefor these compounds having poor in vivo activity is their inability to penetrate thetumour because of metabolism by the biological system. One class of compounds, whichis relatively stable to metabolism by the system and generally has a half life longenough for tumour penetration, is that of nitroimidazoles [28]. More importantly,nitroimidazoles are efficient electron acceptors and are thus considered to be potentiallyuseful radiosensitizers [35] (see Section 1.9.2).1.9.2 Nitroimidazoles as Hypoxic Cell SensitizersThe first two nitroimidazoles tested as sensitizers were metronidazole (Flagyl),a 5-nitroimidazole [36] and misonidazole, a 2-nitroimidazole [37] (Figure 1.2).Both compounds were found to be good sensitizers with a long half life in vivo,although the toxicity of misonidazole was found to limit the doses that may be employedin the clinical setting [38,39]. The use of metronidazole and misonidazole assensitizers appears to be limited by their toxicity; other nitroimidazoles have thus been14Figure 1.2 Examples of some nitroimidazoles that have been developed15synthesized and undergone evaluation. Examples are RSU 1069 which has an aziridineside group [40], Ro 03-8799 (pimonidazole) with a piperidine group [41], SR 2508(etanidazole), an analogue of misonidazole with a peptide containing side group [42],and nimorazole, a 5-nitroimidazole with a morpholine side-chain (Figure 1.2). At thepresent time, on-going tests on RSU 1069 indicate that its toxicity is unacceptable[43], while those for etanidazole show that this drug looks promising as aradiosensitizer [44].1.9.3 Targeting Radiosensitizers to DNAThe use of nitroimidazoles as radiosensitizers is often limited by their inherenttoxicities, but it has been suggested [45] that the nitroimidazole may be rendered lesstoxic by targeting (delivering) the radiosensitizer to the site of the damage, i.e. DNA.In this way, lower doses of the drug could be used, and the toxic side-effects possiblyavoided or reduced while still preserving the radiosensitizing effects of thenitroimidazole.Complexes of Pt [46] and Ru [47] are known to bind strongly to purines andpyrimidines and so the use of these metals as a vehicle to carry the coordinatednitroimidazole to DNA seemed plausible. In this way, the nitroimidazoles would bebrought into proximity with DNA through the binding of the metal to the bases ofDNA. The results of such experiments with nitroimidazole complexes of Pt(II) [48]and Ru [49,50] have been published and, essentially, the ruthenium complexesshow better SER values than the free nitroimidazole ligand while the results with the16platinum complexes are variable [48]; some complexes show greater SER values thanthe free ligand and others show values comparable to those of the free ligand. Ofconsiderable interest, the Ru complexes are less toxic than the free nitroimidazole[49,50], while the toxicities of the free nitroimidazoles increase upon coordination toPt [48].1.10 Other Chemotherapeutic AgentsThere are many compounds that have been specifically designed to kill or inhibitthe replication of cancer cells. The mechanisms by which these anti-cancer agents workare varied (e.g. some "target" DNA and prevent replication, while others inhibitbiochemical pathways that are critical for cell survival). The chemistry (synthesis andmechanisms) of such anti-tumour agents has been well reviewed [51] and onlyselected examples are presented in this chapter.1.10.1 DNA BindersAs DNA is considered to be a prime target in the inhibition of cell replication(especially in rapidly dividing cells), compounds which bind to DNA and inhibitreplication have been synthesized and studied. Examples of such compounds are thosethat are based on the structure of acridine. These compounds have the property ofbinding to DNA by intercalating between the base pairs of the double helix. Thepresence of an intercalator in the DNA strand changes the conformation of the doublehelix which, during enzymatic repair processes, can lead to strand breaks and the17formation of DNA-protein cross links thus preventing replication [52].Biological alkylating agents (defined as compounds that can replace a hydrogenatom with an alkyl group under physiological conditions (pH 7.0 - 7.4, 37°C, inaqueous media)) are also known to induce lethal mutations in DNA and inhibit DNAsynthesis by forming cross links between the various cell proteins present within the cell[53].Transition metal complexes may thus be of use in this respect by binding toDNA through the metal and perhaps changing the conformation of the double helix orcausing cross links that would ultimately result in the inhibition of DNA replication.1.10.2 Hypoxic CytotoxinsThe development of compounds that are differentially toxic towards hypoxic cellsas a result of metabolic bioreductive activation is of some interest; essentially, thisstrategy exploits the ability of the hypoxic cell for reductive biochemistry which isotherwise nullified (e.g. by "redox cycling", see below) or prevented in the presenceof oxygen [54]. Suitable compounds would be those that only become toxic to the cellwhen reduced.The suggestion that nitroimidazoles may be used as hypoxic cytotoxins arosewhen it was established that nitroimidazoles exhibit greater toxicity in hypoxia than inaerobic conditions in vitro [55,56]. A correlation between the increasingradiosensitizing ability and toxicity of the nitroimidazoles with an increase in thereduction potential of the compound has been found [57]. The primary target in the18cytotoxic effects of these nitroimidazoles is assumed to be DNA, and the damage toDNA is thought to result from the reduction products of the compounds [35,58].The reduction of aromatic nitro compounds in mammalian systems bynitroreductases was studied in 1957 [59]. The reductases had few structuralrequirements for substrates and were inhibited by air; the initial step in the reductionwas found to be a one-electron transfer from the enzyme to the nitro compound to formthe nitro anion radical, R-NO2-, which implied the presence of a free-radicalmechanism in the oxygen inhibition of the enzyme [60]. The concept of "redoxcycling" [61] was later proposed to explain the lower levels of toxicity in the presenceof oxygen. The enzymatic reductions also occur in aerobic tissues, but the radical nitroanion is oxidized back to its original form by oxygen. The oxygen is reduced tosuperoxide, which is converted to peroxide by the enzyme superoxide dismutase; theperoxide in turn is converted to H20 and 02 by catalase [62]. In hypoxic conditions,however, the radical anion is reduced further, and these reduction products are thoughtto be responsible for the enhanced toxic effects in the absence of air [35,63].1.10.3 Targeting Metals to Hypoxic AreasThe use of transition metals to target nitroimidazoles has been discussedpreviously (see Section 1.9.3). An alternative intriguing concept is the use ofnitroimidazoles to deliver a radioactive metal to areas of hypoxia [64]. The conceptof redox cycling has been noted previously to account for the preferential toxicity ofnitroimidazoles in hypoxic cells (see Section 1.10.2). It must be possible to synthesize19a complex comprised of a radioactive metal and a reducible nitroimidazole. If theappropriate radioactive emitter is used, these complexes could then be used for targetingand radio-imaging of hypoxic areas. In fact, the original aim of this project was tosynthesize nitroimidazole complexes of Jr [65] and examine the possibility of usingradioactive analogues of such complexes as imaging agents or as local radiation sourcesin hypoxic areas (see Section 1.15).1.11 Metal Complexes as Anti-Cancer AgentsThe preceding sections indicate the potential that transition metal complexes havein various aspects of treating malignant tumours. Organic compounds have been thefocus of most drug research and only in the last three decades has interest grown in thefield of transition metal complexes as potential anti-cancer agents. The general featuresof transition metals that make them good candidates as anti-cancer agents have beenreviewed [8,66] and are summarized briefly in Sections 1.11.2 - 1.11.6. The bestknown metal-based anti-cancer drug is cis-PtC12(NH3)2 (cisplatin) but complexes basedon other metals have shown anti-tumour3 activity, and the potential for developingother metal-based anti-tumour agents is considerable.1.11.1 Cisplatin: Pros and ConsThe development of metal complexes as potential new anti-cancer agents owes3 The term "anti-tumour" is used in its most general sense to imply any kind of effectobserved (toxicity, radiosensitization, etc.) that may be of use against cancer.20a great deal to the discovery of the anti-tumour activity of cisplatin in the 1960s byRosenberg's group [67]. Cisplatin was the most frequently used metal-based anti-tumour drug in the 1980s [68]; this complex increased the cure rates of testicular,ovarian and neck and head cancers but showed little activity against other cancers thattogether account for about 30% of all cancer mortality [69].Apart from the limited spectrum of activity of cisplatin against different tumourtypes, the toxicity of the drug (severe nausea, vomiting and nephrotoxicity) is usuallydose-limiting [69]. As a result, thousands of analogues and derivatives of cisplatin havebeen synthesized and evaluated [69(b),70] but only a handful of second generationdrugs have reached clinical trials, carboplatin probably being the best-known [71] (seeFigure 1.3). While these second generation drugs may show lower toxicities, theirspectrum of activity remains essentially the same as that of cisplatin [69(b)]. Thedevelopment of other drugs based on non-Pt complexes or Pt-complexes with a differentmode of action (see for example ref. 72) will probably circumvent the narrowspectrum of activity shown by cisplatin.1.11.2 Metals in Biological SystemsTransition metals play pivotal roles in many biological systems; for examplespecies of Fe, Co, Cu, and Mo are established in redox reactions [62]. Advantage canbe taken of these naturally occurring systems by substitution with other metals to obtainselective uptake of the metal. For example, Ru appears to resemble Fe in its bio-distribution [73] and in its binding to transferrin, a plasma protein which may afford21Figure 1.3 The structures of some second generation Pt complexes and some recent(*) examples taken from ref. 7222a method of transporting Ru to specific parts of the body [74]. Other metal complexesthat are reported to show selective uptake in tumours include those of 67Ga [75] and111In [76].1.11.3 Metal Complexes vs. Organic CompoundsTransition metals have an advantage over the basic carbon atom of organicmolecules in possessing usable d orbitals. In simple terms, the presence of available dorbitals allows the metal to interact with ligands. Depending on the ligand, the oxidationnumber of the metal and its coordination number, the interactions give rise to complexesof variable geometries. Common forms of isomerism, like cis or trans-PtC12(NH3)2found in square planar complexes, can have profound effects on the biological activityof the system. In the case of PtC12(NH3)2, only the cis form is capable of formingspecific intrastrand DNA links which are assumed to lead to lethal lesions in DNA[77]. As a result, the trans form is a magnitude of order less toxic than the cis formand is completely inactive as a chemotherapeutic agent.Transition metals are capable of existing in various oxidation states dependingon their ligand environment and this leads to several possibilities in the design of drugswith specific properties. Such factors in drug design are considered in Sections 1.11.4and Electron Affinity of Drugs in RadiosensitizationA range of one-electron reduction potentials exist within metal complexes23depending on the metal and the ligand system. Metal complexes with reductionpotentials in the appropriate range could thus be used as radiosensifizers to mimic theoxygen effect in hypoxic tissue. The interaction of radiation with various metalcomplexes has been studied and examples include Fe(CN)63" [78], [Co(NH3)6]3+[79] and Rh(II) carboxylates [80]. The results vary depending on the metal andligand system studied and have been summarized [66]. In general, metal complexessensitize hypoxic cells more than aerobic cells. Since the reduction potential of the metalcentre is considerably dependent on its ligand environment, the reduction potentials ofa metal can be fine-tuned by changing the ligands. For example, the reduction potentialsfor the Ru(III) centre in [RuIII(NH3)5L] changes from -0.08 to +0.9 V when the ligandL changes from hydroxide to a neutral flavin ligand [81].The radiosensitizing ability of the nitroimidazoles appears to be related to thereduction potential of the nitro group [57], so the possibility exists that theradiosensitizing ability of nitroimidazoles may be optimized by changing their reductionpotentials through coordination to a metal. For example, the reduction potential of 4-nitroimidazole becomes more positive (-685 to -615 mV) when bound to Ru(II)-dimethylsulfoxide centres (e.g. in RuC12(DMS0)2(4NO2-1m)2), and this behaviour isaccompanied by an increase in the radiosensitizing ability of the metal complexcompared to that of the free ligand (SER 1.6 and 1.2, respectively) and a decrease inthe toxicity compared to the free nitroimidazole [49]. Similar increases in the SER wereobserved with nitroimidazole complexes of Pt although the toxicities of thenitroimidazoles were also increased upon coordination [48].241.11.5 Lability as a Function of Oxidation StateThe lability of ligands in some complexes is dependent on the oxidation state ofthe metal. Complexes comprised of cytotoxic ligands coordinated to a metal could thusbe reduced by the hypoxic environment of a tumour; the metal could become morelabile and release the cytotoxic ligand for cell kill. This concept was proposed in 1975as a possible explanation for the radiosensitizing abilities of [Co(NH3)6]3+ towardbacterial spores [82]. A more recent example is the Co(III)/(10 system reported byWare et al. [83(a) & (b)] where the authors used the inertness of Co(III) complexesto reduce the toxicity of two cytotoxic ligands, N,N'-bis(2-chloroethyl)ethylenediamine,BCE, and N,N-bis(2-chloroethyl)ethylenediamine), DCE (see Figure 1.4) throughchelation to the metal. In the reducing environment of hypoxic cells, Co(III) is reducedto the more labile Co(II) species which quickly undergoes exchange with H20 to formFigure 1.4 The structures of the Co/DCE/BCE complexes used by Ware et al. (adaptedfrom ref. 83(a) & (b))25the non-toxic aquated Co(II) species, while releasing the now active cytotoxic ligand.In this way, the ligand is delivered to areas of hypoxia and so selective toxicity isachieved. In addition, the reduction potentials of the Co system are reportedly dependenton the substituents at the ligand nitrogen donors, and this therefore affords more finetuning of the complex to obtain specific reduction characteristics. It is thus conceivablethat metal complexes could be designed with the appropriate reduction potentials forthe purpose of delivering cytotoxins or radiosensitizers only to hypoxic cells, thusincreasing specificity and improving existing treatment modalities.1.11.6 Radioisotopes for ImagingRuthenium compounds with nitrogen-donor ligands are reported to localize intumour tissues [84], and analogous complexes could be made with correspondingradioisotopes of the metal for radiodiagnostics to image or locate the tumour. Clarke hassummarized some of the mechanisms thought to be responsible for this selective uptake[85] and examples of such imaging agents include the use of radio ruthenium(III)iminodiacetato complexes [86].1.12 Non-Platinum Metal Complexes as Anti-Cancer AgentsThere has been much work done in this field since the advent of cisplatin andseveral reviews both general and specific have appeared in the literature[e.g.8,66,87,88]. The variety of complexes studied is astonishing and ranges frommain group inorganic compounds to coordination complexes and organometallic26derivatives of the transition metals. The examples mentioned here (see Figure 1.5) aremeant to simply illustrate the variety of complexes that exist. An extensive coverage ofthis field of research is available through ref. 88(b).Few inorganic compounds from the main group metals have been found activeas anti-cancer agents. The nitrates of group 13 metals (Al, Ga, In, 11) have someactivity in certain tumour models [89]; the most promising compound is galliumnitrate which has reached Phase II clinical trials [90].Transition metals appear to have more potential as anti-tumour agents with awider range of complexes showing some anti-tumour activity. The examples shown hereare ones that have been studied extensively or have gone on to clinical trials.Bis(1-pheny1-1,3-butanedionato)diethoxytitanium(IV), also known as budotitane,has been investigated extensively [91], and Phase I trials began in 1986 [92]. Thezirconium and hafnium analogues were generally less active [93]. Compounds ofiridium have been little studied, although anti-tumour properties have been observed forhexachloroiridate(IV) salts [94].Auranofin, 2,3,4,6-tetra-o-acety1-1-thio*D-glucopyranosato-S-(triethylphosphine)gold(I), used as an anti-inflammatory drug, has been testedextensively in vitro as an anti-tumour agent but showed disappointing results in vivo[95]. Of potentially more interest, however, are the binuclear complexes of gold withdithioerythritol, a bridging dithiolate ligand, which show more activity [96].From studies on the synthesis, structure and anti-tumour activity of Ru(III)imidazole complexes [97], transtImH][RuC14(Im)2]) (imidazolium tetrachlorobis-27Et 3 PAu —S\ C = N/S\C - NEt 3 PAu _S"(Et3PAu)2- p-(2,5-dimercapto-l-thia-3,4-distzole)--T1------- °0^.^Et0 ______--- --___' 0 aBudotitaneNCH CH CH Is{2 2 2 \^•21iaCH3CH3_Ph 3PAu —S — CH2ICHOHICHOHIPh 3PAu ---S— CH2(Ph 3 PAu) 2-11-(dithioerythritol)0I ICH OCCH3AuranofinSpirogermanhunFigure 1.5 Examples of non-platinum metal complexes with reported anti-tumouractivity28(imidazole)ruthenate(III), ICR) has been reported [98] to show promising anti-tumouractivity towards various tumour lines. Other examples of ruthenium complexes thatshow anti-tumour activity include the ruthenium-amine complexes such as fac-RuC13(NH3)3 and [cis-RuC12(NH3)4]Cl that Clarke et al. have studied [99].Organometallic compounds have also contributed to the rapidly growing arsenalof metal-based chemotherapeutic agents. For example, spirogermanium, a heterocyclicGe compound, has entered clinical trials and is active against a large number of humantumour types, including cervix carcinoma [100], metastatic prostate cancer [101]and breast cancer [102]. Other examples of organometallic complexes include thoseof Rh(I) and Ir(I) with 1,5-hexadiene, 1,5-cyclooctadiene and norbornadiene [103].From this brief review, one can see that many coordination and organometalliccompounds of transition metals have potential as anti-cancer agents although it is clearthat the results vary greatly from metal to metal and ligand to ligand. This in itselfpoints to the need for a more systematic investigation of these and other relatedcomplexes which may lead to some general trends that can be applied to better drugdesign.1.13 Ruthenium SulfoxidesSulfoxides have been known as Lewis bases for some time (through ref. 104)but studies into the coordination chemistry of these ligands were initiated only in the1960s [105]. Since that time, an enormous amount of work has been published onsulfoxide complexes of the transition metals and the findings, at least to about 1980,29have been well reviewed in the literature [104]. Because of the emphasis of the presentthesis work on ruthenium sulfoxide complexes, a brief survey of such species reportedat the onset of the thesis work will be presented. The coordination chemistry ofsulfoxides is enriched by the possibility of either oxygen- or sulfur- bonding (seeChapter 3) as well as chirality within R1R2S0 sulfoxides where R1 and R2 are differentalkyl/aryl groups. The anti-tumour properties of ruthenium sulfoxides are treatedseparately in Section 1.14.Our group has been interested in sulfoxide complexes of ruthenium since theearly 1970s especially as potential catalysts for homogeneous hydrogenations. Cis-RuC12(DMS0)4 was first prepared in these laboratories from the reduction ofRuC13.3H20 in DMSO using H2 [106], and later structurally characterized, also atUBC [107]. An alternative route to the complex, without the use of H2, wasreported later by Evans et al. [108]. Subsequent studies at UBC have led to othercomplexes including [NH2Me2][RuC13(DMS0)3] which catalyzed the hydrogenationof acrylamide to propionamide, and ethyl vinyl ketone to ethyl methyl ketone [109];in 1978, Ru(DMS0)62+ was prepared and characterized and this complex alsocatalyzed the H2-reduction of acrylamide under mild conditions [110].Ruthenium(II) complexes with chiral sulfoxides have also been prepared and theirpotential as catalysts for asymmetric hydrogenation evaluated using as ligands, dios,bdios, and ddios (thia analogues of the chelating phosphine derivative, diop),Figure 1.6. The chiral complexes showed some catalytic activity for the hydrogenationof prochiral unsaturated carboxylic acid substrates such as itaconic acid [111]30MeH' CH 2so CH3DIOSH H0---„..-CI! 2SO CH20me^0,,,,,___ CH 2S0 CH3KH CH 2S° CHASBDIOSHO• CH SO CH2^3HO"- 'H ' CH 2S0 CH3DDIOSR-(+)-methyl p-tolyl sulfoxide0CH CH ,-.CH CH S3 z,^2 \ c„HCH3^3(S,R;S,S)-(+)-2-methylbutyl methyl sulfoxideFigure 1.6 Some examples of chiral sulfoxides used in catalytic asymmetrichydrogenation studiesTrimeric complexes of the form [RuC12L2]3 (where L = R-(+)-methyl p-tolylsulfoxide or (S,R;S,S)-(±)-2-methylbutyl methyl sulfoxide, see Figure 1.6) andpolymers like [RuCl21.,2]n (L= methyl phenyl sulfoxide) were also prepared andshowed catalytic activity towards terminal olefins and itaconic acid, although reductionof the substrate occurred together with formation of ruthenium metal [112].Binuclear ruthenium sulfoxide complexes have also been reported in the literatureand these include [RuBr3(N0)(Et2S0)]2 containing 0-bonded diethylsulfoxide; thecomplex was obtained when a solution of the sulfide complex, RuBr3(N0)(Et2S)2, wasexposed to sunlight [113]. The binuclear compound [Ru2C14(DMS0)5] was firstreported by Hudali et al. [114] who formulated the complex with two bridging31chlorides, a bridging DMSO, terminal chlorides and both 0 and S-bonded terminalsulfoxides. This formulation was later revised and reformulated as a triply chlorobridged structure with exclusively terminal S-bonded sulfoxides [115]; this structurehas recently been confirmed by a group in Trieste via crystallographic studies [116].Bora and Singh have also studied sulfoxide complexes of ruthenium(II) and (III)and have reported the preparation of RuX3L3 (X =C1, Br; L= nPr2S0 or nBu2S0)[117] and of RuX2(TMS0)4 (X =C1, Br) [118], although these species were notcharacterized by X-ray crystallography.Reports on the synthesis and characterization of sulfoxide complexes of Ru(II)and (III) [119] (mer- and fac-RuC13(DMS0)3 amongst others) have appeared as wellas reports on the catalytic activity of RuBr2(DMS0)3 [120] but some of theformulations have since been corrected by our group [121] and the Trieste group[172(a)] in attempts to repeat the work.From even this brief summary of ruthenium sulfoxides, it can be seen that thereis a wide range of complexes and structural types that can be obtained. The range ofsulfoxide ligands used, with the exception of the chiral ones, is small, however, and thisrange has been extended in this present work to include simple chelating sulfoxides andsulfoxides with aryl and longer alkyl groups. The synthesis and characterization of thesenew complexes is presented in Chapter 2 and a comprehensive discussion of the richchemistry of ruthenium complexes of DMSO and TMSO is presented in Chapter 3,while Ru complexes of other sulfoxides (including chelating ones) are discussed inChapter 4.321.14 Ruthenium Sulfoxides as Anti-Cancer AgentsThe importance of work on anti-cancer agents based on transition metals otherthan Pt is obvious, in view of the fact that few of the derivatives of cisplatin synthesizedhave reached clinical trials [88,122]. The use of drugs based on other metals maythus extend the spectrum of activity shown by cisplatin via mechanisms that differ fromthose of platinum compounds.Several examples of non-platinum complexes that have been studied are reviewedbriefly in Section 1.12. Of these complexes, those of ruthenium appear to be verypromising, with the ruthenium-amine [123] and the ruthenium-imidazole complexesabout to begin Phase 1 clinical trials [97,98].Sulfoxide complexes of ruthenium are also of interest as anti-tumour agents forseveral reasons. The toxicities of cis- and trans-RuC12(DMS0)4 compared to cisplatinare lower [124] and so are an advantage generally in treatment schedules. Theabsence of amines in the ruthenium complexes may lead to mechanisms of activitywhich may perhaps differ from those of Pt-amine complexes. The treatment of Pt-resistant tumours may then be possible with such ruthenium complexes. As rutheniumsulfoxide complexes are the focus of this thesis, the anti-tumour activity of cis- andtrans-RuC12(DMS0)4 are discussed separately and the salient points highlighted below.1.14.1 Cis-RuC12(DMS0)3(DIUSQ)The anti-tumour properties of cis-RuC12(DMS0)4 have been studied extensivelyfor some time now [103(c),125] and the main features summarized [126]. The33interaction of this complex with DNA and its bases appears to stabilize the conformationof DNA [127], in contrast with other nitrogen-containing ruthenium compounds[128] and cisplatin [129] which destabilize the helical chain. Destabilization of theDNA chain is thought to be due to formation of intrastrand bonds between two DNAbases and the metal complex. With cis-RuC12(DMS0)4, however, the complex isthought not to form intrastrand bonds but rather to be located in the major groove ofDNA. In addition, interstrand crosslinks via the complex, which also lead tostabilization, have been ruled out by other experiments [127].The interactions of nitrogen-containing Ru complexes with DNA bases have beenstudied and it is known that Ru(II) complexes react preferentially with the N-7 ofguanine [130], N-1 of adenine [47(a)] and N-7 of cytosine [47(b)], the most reactiveposition being N-7 of guanine [131]. In the case of cis-RuCl2(DMS0)4, Cauci etal. [127] suggest that the most probable binding sites are the N-7 of guanine in DNA,and the N-7 of adenine in polybase strands.1.14.2 Trans-RuC12(DMS0)4The title complex was synthesized and characterized [121,124] almost 20 yearsafter the cis isomer, which was first made in 1969 at UBC by the James group [106].In contrast to the cis isomer, with three S-bonded and one 0-bonded sulfoxide, the transcomplex has all S-bonded sulfoxides. Extensive studies have been done on the aqueousbehaviour and the anti-tumour activity of both isomers [124]. The two isomers releasesulfoxides quickly upon dissolution in H20, the trans isomer releasing two sulfoxides34vs. one 0-bonded sulfoxide for the cis isomer. Both complexes then undergo sloweraquation with dissociation of one chloride to form the corresponding cationic species.As a consequence, the trans isomer has three aquated coordination sites available whilethe cis isomer has two. The authors speculate that the trans isomer, having threeavailable sites, can react faster than the cis isomer and therefore exhibits greater activity[124].The anti-tumour activities of the two isomers have been compared with that ofcisplatin using Lewis Lung Carcinoma tumour models [124], and it was shown that thetrans form is 20 times more active than the cis and is more efficient in reducing thenumber and weight of spontaneous lung metastases (by 70% vs. 50% of control tumoursfor the trans and cis isomer, respectively). In this assay, 20 times the amount of the cisisomer was required to achieve the same end point as the trans isomer. Compared withcisplatin, however, both complexes were less efficient (on a molar basis) although theyare less toxic than cisplatin [124,125].The interaction of the trans complex with nucleobases of DNA has also beenstudied [132] and the evidence indicates that coordination of the nucleobase 5'-DGMP occurs through chelation of N-7 and an a-0 of the phosphate group, in contrastto the formation of a bisnucle,otide complex which is found for Pt(II) and Pt (IV)complexes [133].Further tests done by Cauci et al. [134] on the trans complex with 2-deoxyguanosine show, however, that two purine bases can coordinate, through the N-7of guanine, in a cis configuration at the metal centre. This type of binding is known for35Pt(II) complexes [135] and is thought to be similar to the kind of adduct (two baseson the same strand of DNA binding to Pt) formed in DNA that is responsible for cellkill [136]. Such binding may be responsible for the anti-tumour activity of trans-RuC12(DMS0)4, but additional work still needs to be done to determine the exact modeof binding.1.15 The Aims and Evolution of the ProjectFrom the outset of this project, it was clear that there was considerable scopein studying the potential for obtaining useful anti-cancer agents containing transitionmetals. The objectives of this present work were not to synthesize new compounds foranti-tumour testing but to take advantage of the preferential reduction of nitroimidazolesin hypoxia (Section 1.10.2) to deliver a metal to hypoxic areas. The initial goal was tosynthesize a compound that was stable enough to reach the hypoxic cells and deposit themetal there either as a cytotoxic agent or an imaging agent.The rationale was that a nitroimidazole complex of Ir(III) would be stable enoughto survive the metabolic pathways of the body as Ir(III) complexes are relatively inert,and that the nitroimidazoles would remain intact due to redox recycling in oxygenatedareas (see Section 1.10.2). In the reducing environment of the hypoxic cell, however,it was thought that reduction of the nitroimidazole might lead to accumulation of themetal in some way in the cell (binding to DNA, reduction to Ir(I) which is more labilethan Ir(III), or decomposition of the complex). Once a suitable complex was found, thelong term goal was to synthesize a radioactive analogue using a radioisotope of Ir for36imaging using radio diagnostic methods. In this way, the areas of hypoxia in a tumourcould be better defined and the dynamics of hypoxia possibly studied.Unfortunately the relative inertness of Ir(III) chemistry, amongst other factors,was a major stumbling block that prevented the project from proceeding beyond theinitial stage, the attempted synthesis of a suitable complex (see Appendix E), and thedetails of this chemistry still remain to be solved.At the same time, occasional forays into ruthenium sulfoxide chemistry weremade in order to resolve some structural questions that remained unsolved from anearlier project [137] carried out within this interdisciplinary programme set upbetween the Chemistry department at UBC and the Medical Biophysics Department atthe B.C. Cancer Research Centre. Also, further reports from the Trieste group(summarized in Sections 1.14.1 and 1.14.2) were published indicating more extensivelythe potential of ruthenium sulfoxides as anti-cancer agents in their own right.It was then decided that the range of sulfoxides used previously with rutheniumshould be extended. The majority of work done with sulfoxide complexes of Ru hadbeen carried out using DMSO or TMSO and, to the best of our knowledge, there werefew examples of other sulfoxide complexes of ruthenium in the literature. It was alsodecided that the use of sulfoxides should be extended to include chelating ones to limit,and to provide a better data base for, the possible geometries of the complexes ingeneral and perhaps to further stabilize these species compared to the monodentatesulfoxide complexes.The extension of the ruthenium sulfoxide chemistry has been undertaken and, in37this present work, the synthesis and structural characterization (including X-raydeterminations) of new complexes are presented (Chapters 3 and 4). The results of somein vitro studies (including accumulation in cells and binding to DNA) are summarizedin Chapter 5.38Chapter 2: The Synthesis and Characterization of Sulfoxides andSulfoxide Complexes of ROI) and Ru(III)2.1 Chemicals and ReagentsDimethylsulfoxide (DMSO) was purchased from BDH, tetramethylene sulfoxide(TMSO) and 4-nitroimidazole from Aldrich, di(n-propyl)sulfoxide (nPr2S0) and 3,6-dithiaoctane from Pfaltz & Bauer and the following sulfoxides and sulfides from K &K Labs: di(n-butyl)sulfoxide (nBu2S0), racemic methylphenylsulfoxide (MePhS0),diphenylsulfoxide (Ph2S0), 2, 7-dithiaoctane, 3, 8-dithiadecane and 4,7-dithiadecane. Thechemicals were used as provided with the exception of TMSO which was vacuumdistilled prior to use. RuC13.3H20 (39.9% Ru content) was a loan from JohnsonMatthey. All common solvents used were at least of reagent grade. Methanol was driedover Mg turnings, Et20 over Na/benzophenone, and CH2Cl2 over P205; solvents weredried for at least 2 11 before use.2.2 Physical Techniques and MethodsInfrared spectra (KBr discs or Nujol mulls) were recorded on a Nicolet 5DXFTIR spectrometer (calibrated with a polystyrene strip) and 1H NMR spectra on VarianXL-300 or Bruker WH-400 instruments operating in the Fourier Transform mode, withTMS as the reference. Optical density measurements were recorded on a Perkin Elmer552A spectrometer with quartz cells (0.5 or 1.0 cm) unless stated otherwise.Conductivity measurements were made at room temperature at 10-3M concentrations39using a Thomas Serfass conductivity bridge, and a cell from Yellow Springs InstrumentCompany. Magnetic moments were measured using Evans' method [138] using tert-butanol as the internal reference; measurements in the solid state were made using aJohnson-Matthey magnetic susceptibility balance. Molecular weights were determinedusing the Signer method; the reference compound used in all determinations was 1,2-bis(propylsulfinyl)ethane [139]. Elemental analyses were performed by P. Borda ofthis department. Standard Schlenk tube techniques were used in the synthesis of theruthenium complexes with Ar being used to exclude air, unless stated otherwise. Allsamples were stored in air, and all measurements were done in air unless statedotherwise. Single crystal X-ray structural determinations were performed by Dr. S.J.Rettig of this department.2.3 Synthesis of the SulfoxidesDiethylsulfoxide was the only monosulfoxide synthesized as the other sulfoxideswere commercially available. The disulfoxides were synthesized in air by acid catalyzedDMSO oxidation of the corresponding disulfides following the procedure reported in theliterature [140]. All the disulfoxides except 1,4-bis(ethylsulfinyl)butane had beensynthesized and characterized previously by elemental analysis and infrared spectroscopyalthough no 1H NMR spectra had been reported [140]. The IR data for vso for thedisulfoxides synthesized during this present work compare well with those reportedearlier [140]; in addition, the proton NMR spectra of the sulfoxides were measured andreported in this present work.402.3.1 Diethylsulfoxide (Et2S0)Diethylsulfoxide was prepared by oxidation of diethylsulfide with H202according to procedures reported in the literature [141]. Diethylsulfide (20 mL, 186mmol) was added to acetone (15 mL) at 0°C with continuous stirring. 30% H202 (18mL, 158 mmol) was added dropwise to the acetone solution, and the reaction mixturestirred for 20 min at 0°C. The reaction solution was then allowed to warm to roomtemperature and left for 30 minutes. Acetone and water were removed from the clearreaction solution by evaporation, and the sulfoxide was isolated as a clear and viscousoil. Yield: 77%. IR vso•• 1001 cm-1. 1H NMR (300 MHz, Me0D): 6 1.25 (t, 3H,CH3), 2.62 (m, 2H, CH2). The spectral data determined here agree well with thosereported previously [142].2.3.2 1,2-Bis(methylsulfinyl)ethane (BMSE)A solution consisting of 2,5-dithiahexane (10 mL, 85 mmol) in DMSO (20 mL,281 mmol) and a catalytic amount (0.2 mL) of concentrated HC1 was heated for 8 h at85°C with continuous stirring. The sulfoxide precipitated as fine white crystals whenthe reaction mixture was cooled to room temperature. The crude product was collectedand washed with benzene and ether to remove residual DMSO and DMS. The filtratewas heated again for a further 4 h, and more product was obtained. Yield: 85%. Thesulfoxide was recrystallized from Et0H (40 mL) three times before further use. Anal.calc. for C4H1002S2: C, 31.16; H, 6.49. Found: C, 31.06; H, 6.42%. IR uso: 101841cm-1. 1H NMR (300 MHz, D20): 6 2.68 (s, 3H, CH3); 3.15 (m, 2H, CH2).2.3.3 1,2-Bis(ethylsulfinyl)ethane (BESE)A catalytic amount (0.1 mL) of concentrated HC1 was added to a solution of 3,6-dithiaoctane (5 mL, 33 mmol) in DMSO (5.5 mL, 77 mmol), and the reaction mixtureheated at 85°C for 10 h with continuous stirring. The sulfoxide precipitated as a whitecrystalline material when the reaction mixture was cooled to 0°C. The crude productwas washed with diethylether, and the filtrate heated for a further 21/2 h to obtain moreproduct. Yield: 65%. The crude product was recrystallized from hot Et0H (15 mL)twice before use. Anal. calc. for C6F11402S2: C, 39.56; H, 7.69. Found: C, 39.69;H, 7.59%. IR vso: 1015 cm-1. 1H NMR (300 MHz, Me0D): 6 1.33 (t, 3H, CH3);2.78 (m, 2H, CH3-CH2); 3.02 (m, 2H, CH2-S(0)).2.3.4 1,2-Bis(propylsulfinypethane (BPSE)4,7-Dithiadecane (3.29 g, 18 mmol) was added to a solution of DMSO/HC1 (3%v/v, 6 mL) and the mixture heated at 85°C for 3 h. The sulfoxide precipitated when thereaction mixture was cooled to 0°C; the crude sulfoxide was collected and washed withcold acetone and ether to remove residual DMSO and DMS. The remaining filtrate washeated for a further 4 h, and more precipitate was obtained. Yield: 70%. The crudeproduct was recrystallized from hot benzene (45 mL) twice before use. Anal. calc. forC8H1802S2: C, 45.71; H, 8.57. Found: C, 45.55; H, 8.58%. IR vso: 1010 cm-1. 1HNMR (300 MHz, CD2C12): 3 1.10 (t, 3H, CH3); 1.85 (m, 2H, CH2-CH3); 2.80 (AB42qt, 2H, CH3-CH2-CH2); 3.20 (AB qt, 2H, (0)S-CLI2-CH2).2.3.5 1,3-Bis(methylsulfinyl)propane (BMSP)The thioether corresponding to the sulfoxide, 2,7-dithiaheptane, was notcommercially available and was thus synthesized following the procedure of Morgan andLedbury [143]. Methyl mercaptan (8 mL) was condensed in a measuring cylindercooled in a Dewar of liquid nitrogen and added to a saturated solution (15 mL) ofNaOH in Me0H, previously cooled in a dry ice/acetone bath. 1,3-Dibromopropane (7mL) was then added to the methanolic solution dropwise with constant stirring. Theresulting mixture was stirred for 30 min and then allowed to warm to 0°C before beingpoured into water (100 mL). The oily thioether was immiscible with water and wascollected using a separatory funnel. The aqueous layer was extracted three times withether (15 mL portions); the organic residues were combined, the ether removed byevaporation, and the oily product dried over magnesium sulfate before being used in thenext step. 1H NMR (300 MHz, CDCI3): (5 1.85 (qn, 1H, CH2-CH2-CH2), 2.08 (s, 3H,CH3), 2.61 (t, 2H, CH2-S).The thioether (6.18 g, 45 mmol) was added to a solution of DMSO/HC1 (3%v/v, 11 mL), and the reaction mixture heated at 85°C for 7 h. The sulfoxideprecipitated slowly after the reaction mixture was cooled to 0°C and the sides of theflask were scratched. The crude product was collected and washed with ether andbenzene. The filtrate was heated for a further 4 h, and more product was obtained.Yield: 70%. The crude sulfoxide was recrystallized three times from hot THF (100 mL)43before further use. Anal. calc. for C51-11202S2: C, 35.71; H 7.14. Found: C, 35.78;H, 7.16%. IR vso: 1050 cm-1. 1H NMR (300 MHz, CDC13): (5 2.37 (m, 1H, CH2-CH2-CH2); 2.60 (s, 3H, CH3); 2.89 (m, 2H, CH2-S0).2.3.6 1,4-Bis(methylsulfinyl)butane (BMSB)2,8-Dithiaoctane (4 g, 26 mmol) was added to a solution consisting of DMSO(8 mL, 112 mmol) and concentrated HC1 (0.1 mL), and the reaction mixture heated at85°C overnight. The crude product precipitated when the reaction mixture was cooledto 0°C and the sides of the flask scratched. The precipitate was collected and washedwith benzene and ether; the filtrate was heated for a further 3 hours, and moreprecipitate obtained. Yield: 52%. The product was recrystallized from hot ethyl acetate(80 mL) three times before use. Anal. calc. for C61-11402S2: C, 39.56; H, 7.79.Found: C, 39.41 H, 7.74%. IR vso: 1049 cm-1. 1H NMR (300 MHz, CDC13): (5 2.01(m, 4H, CH2-CH2) ; 2.61 (s, 6H, 2 x CH3); 2.78 (m, 4H, 2 x CH2-S0).2.3.7 1,4-Bis(ethylsulfinyl)butane (BFSB)3,8-Dithiadecane (2 g, 17 mmol) was added to a solution of DMSO/HC1 (3%v/v, 5 mL) and the reaction mixture heated at 85°C for 4 h. The sulfoxide precipitatedwhen the reaction mixture was cooled to 0°C; the crude product was collected andwashed with benzene and ether. The filtrate was heated for a further 2 h, and moreprecipitate was obtained. Yield: 55%. The crude product was recrystallized twice fromhot benzene and hexane (3:2 v/v, 45 mL). Anal. calc. for C81-11802S2: C, 45.71; H,448.57. Found: C, 45.52; H, 8.78%. IR uso: 1012 cm-1. 1H NMR (300 MHz, CDC13):(5 1.35 (t, 6H, 2 x CH3); 1.96 (m, 4H, CH2-CH2); 2.70 (two overlapping m, 8H, 2 xC_H2-S (0)-C1_12-CH3).2.4 Synthesis of the Monodentate Sulfoxide Complexes of Ruthenium2.4.1 The "Ruthenium-Blue" SolutionsThe majority of the ruthenium sulfoxide complexes synthesized in this presentwork were obtained from reaction of the sulfoxide with the "ruthenium-blue" solutionswhich were generated by refluxing a methanolic solution of RuC13.3H20 under H2.These "ruthenium-blue" solutions are well known as synthetic precursors to many Ru(II)and Ru(III) complexes [144] although the composition of the solutions still remainspoorly defined [145].The "ruthenium-blue" solutions appear to contain several species in anequilibrium that is dependent on the pH and chloride ion concentration of the solution[145]. Three of these species have been identified as dimeric Ru(II)/(III) species of thetype Ru2C13+n(2-)1- [146]. The presence of these mixed-valence rutheniumchloride dimers may perhaps account for the isolation of some Ru(III)/sulfoxidemonomers and Ru(II)/(III) dimers in this present work (see Chapter 4) despite thereducing conditions used in the generation of the "blue solutions".2.4.2 Cis-RuC12(DMS0) 4Cis-RuC12(DMS0)4 was synthesized from the "ruthenium-blue" solutions45(Section 2.4.1) and by refluxing a solution of RuC13.3H20 in DMSO in air [108]. Theformer method is more reliable albeit the yields are lower while the latter method hashigher yields but is more variable.2.4.2(a) A solution of RuC13.3H20 (0.25 g, 1 mmol) in Me0H (20 mL) wasrefluxed in an atmosphere of H2 until the solution became dark blue (4 h); DMSO (3mL, 42 mmol) was then added to the "blue-solutions" and refluxing continued under H2for a further 6 h. The complex formed after this period and precipitated as a fine yellowpowder. The reaction mixture was filtered while hot, and the precipitate washed withacetone before being dried at 70°C in vacuo. Yield: 45%. Anal. calc. forC8H24C1204RuS4: C, 19.38; H, 4.99. Found: C, 19.42; H, 5.01%. Xmaxnm (log 6),CH2C12: 355 (3.02); 305 (2.87). IR uso: 1115, 960 cm-1. 1H NMR (300 MHz,CDC13): 6 2.62 (free DMS0); 2.75 (Q-bonded DMS0); 3.45, 3.46, 3.52, 3.55 (S-bonded DMSO). The spectroscopic data agree well with those previously reported[108,172(c)]. The 1H NMR spectrum of cis-RuC12(DMS0)4 in CDC13 is complicatedand the peak assignments have been reported in the literature [108].2.4.2(b) RuC13.3H20 (2.00 g, 7.6 mmol) was dissolved in DMSO (8 ml, 112mmol), and the reaction mixture refluxed for 20 min in air. The complex precipitatedas a fine yellow crystalline powder when the reaction mixture was cooled to roomtemperature. Acetone (30 mL) was added and more complex precipitated. The yellowprecipitate was collected in air and dried in vacuo at 70°C. Yield: 85%. The physicaldata are as above. Crystals which proved from spectral data to be the trans isomer werealso obtained from the remaining filtrate after a few months.462.4.3 Trans-RuC12(DMS0) 4The trans isomer of the tetralcis DMSO complex was obtained in several ways[121,124] (see also Section 3.8.2(a), p.79). RuC13.3H20 (0.25 g, 1 mmol) wasdissolved in DMSO (1.5 mL, 21 mmol) and the solution heated at 70°C for 15 min.The resulting red solution was cooled to room temperature and acetone (30 mL) addedslowly with constant stirring. A red solid precipitated which was collected,recrystallized from hot DMSO (5 mL) and acetone (30 mL) and dried in vacuo at 70°C.Yield: 76%. Anal. calc. for C8H24C1204RuS4: C, 19.38; H, 4.99. Found: C, 19.35;H, 5.01%. Xmaxnm (log €), CHC13: 440 (2.35); 2.85 (3.11). IR usco: 1086 cm-1. 1HNMR (300 MHz, CDC13): 6 2.62 (free DMS0); 3.39 (s, S-bonded CH3). Thespectroscopic data agree well with those reported in the literature [121,124,172(c)]. Thisroute to trans-RuC12(DMS0)4 was, however, found to be variable and would sometimesyield Ru2C16(DMS0)4 (see Section 2.4.4 below).2.4.4 Ru2C16(DMS0)4In other attempts to synthesize trans-RuC12(DMS0)4 using the proceduredescribed in Section 2.4.3 and in the literature [121], the title compound was obtained(see Section 3.8.6 (p.91) for discussion). RuC13.3H20 (0.25 g, 1 mmol) was dissolvedin DMSO (1.5 mL, 21 mmol), and the reaction mixture heated at 70°C for 15 min. Theresulting red solution was cooled to room temperature, and a red powder precipitatedwith the addition of acetone (30 mL). The complex was collected in air and47recrystallized three times in DMSO/acetone (1:10 v/v) and dried in vacuo at 70°C.Yield: 55%. The complex is soluble in acetonitrile and DMSO, sparingly soluble inCH2C12 but insoluble in other common organic solvents. Anal. calc. forC8H24C1604RuS4: C, 13.26; H, 3.30; Cl, 29.29. Found: C, 13.26; H, 3.48; Cl,29.58%. Xmaxnm (log €), DMSO: 463 (3.87); 356.3 (3.68); CH3CN: 462.4 (3.65); 357(3.47); CH2C12: 465, 358. IR vso: 1032, 985 and 891 cm-1. 1H NMR (300 MHz,CD3CN): S 2.62 (free DMS0); 3.42 ppm (S-bonded DMSO). In CDC13, (3 2.63 ppm(s, free DMSO). The magnetic moment of the complex in the solid state (geff = 0 BM)showed that the complex was diamagnetic. When solutions of the dinuclear species,Ru2C16(DMS0)4, in DMSO were refluxed, cis-RuC12(DMS0)4 was obtained as a fineyellow precipitate while trans-RuC12(DMS0)4 was obtained by exposing similarsolutions to sunlight (see Section 3.8.6).2.4.5 Ru2C14(DMS0)5This compound was isolated in attempted sulfoxide exchange reactions betweencis-RuC12(DMS0)4 with 1ZPr2S0 and nBu2S0. In both cases, the dimeric DMSOcomplex was isolated. This complex was previously synthesized in a similar manner[114,115], and a typical reaction is described below.Cis-RuC12(DMS0)4 (0.29 g, 0.6 mmol) was dissolved in a solution containingMe0H (20 mL) and nPr2S0 (0.85 mL, 1.63 mmol); the reaction mixture was thenrefluxed in air. A bright yellow precipitate formed after 15 min; the precipitate wascollected and dried in vacuo at 70°C. The compound is insoluble in most common48organic solvents but is soluble in H20 and DMSO. Anal. calc. forC10H30C1405Ru2S5: C, 16.34; H, 4.10. Found: C, 16.16; H, 4.49. Xmaxnm (log e),H20: 356 (3.00); 303 (2.85). IR uso: 1111, 1087, 1022, 974, 925 cm-1. 1H NMR(300 MHz, D20): (5 2.63 (free DMS0); 2.74 (0-bonded DMS0); 3.43, 3.45, 3.52,3.56 (5-bonded DMSO). No peaks for the complex were found in the mass spectrum(El and FAB); only those peaks due to the matrix were found in the FAB spectrum.2.4.6 Cis-RuC12(TMS0)4RuC13.3H20 (2.00 g, 7.65 mmol) was refluxed in Me0H (40 mL) under an H2atmosphere for about 4 h when the colour of the solution turned from deep brown todeep blue. TMSO (8 mL, 89.1 mmol) was added and refluxing continued under H2 fora further 4 h, generating a yellow-green precipitate. The reaction mixture was filteredhot, and the fine yellow powder was collected, washed with cold acetone (10 mL), anddried in vacuo at 70°C. Yield: 95%. Yellow crystals suitable for X-ray analysis wereobtained by dissolving the powder in hot Me0H, followed by a slow cooling of themixture. Anal. calc. for C16H32C1204RuS4: C, 32.60; H, 5.44. Found: C, 32.65; H,5.58%. Xmaxnm (log c), CHC13: 355 (3.03); 300 (2.76). IR uso: 1121, 1064 cm-1.1H NMR (300 MHz, CDC13): (5 2.26 (m, 4H, CH2-CH2); 3.44, 4.13 (m, 2H each,CH2-S(0)-CH2).A different crystal form of the same complex was obtained following anattempted reaction of cis-RuC12(TMS0)4 (0.286 g, 0.49 mmol) with a 2-nitroimidazolederivative called etanidazole (0.141 g, 0.66 mmol), using a 6 h reflux procedure in49Me0H (30 mL) under N2. The resulting blue solution was filtered hot, concentrated toa volume of 10 mL and cooled at 0°C; both crystal forms of the complex(distinguishable by the colour, one crystal form being green and the other yellow)appeared overnight and were collected by filtration, washed with cold acetone and air-dried.2.4.7 [RuBr3(TMS0)4Li]2The original synthesis of this complex was carried out by Dr. J. Jaswal, aformer member of this group, and the details were published in refs. 171(b) & (c). Thereaction was repeated during the course of this present work, and the details aredescribed here.RuC13.3H20 (0.25 g, 1 mmol) and LiBr (1.0 g, 11.5 mmol) were dissolved indry Me0H (20 mL), and the solution was refluxed for 30 min in air. The resulting darkred solution was then filtered while hot and TMSO (1.5 mL, 17 mmol) added.Refluxing was continued for another 2 h. The resulting orange solution was concentratedto 5 mL and left at 0°C overnight. The resulting yellow precipitate was collected,washed in CC14 and dried in vacuo at room temperature. The remaining filtrate was setaside, and more of the complex precipitated. Yield 45%. Anal. calc. forC1 6H32 Br3LiO4RuS4: C, 25.14; H, 4.1. Found: C, 25.58; H, 4.38%. Xmaxnm (log6), CH2C12: 375 nm. IR uso: 1043, 1114 and 1127 cm* 1H NMR (300 MHz,CDC13): (5 2.15, 2.32, 2.90, 3.53 and 4.10 (complex br m). The protons of the variousTMSO ligands present in the complex could not be assigned unambiguously due to the50complexity of the 1H NMR spectrum.2.4.8 Cis-RuBr2(TMS0)4In a repeat of the reaction described in Section 2.4.7, the CC14 washingsdeposited yellow crystals which had the following spectral data: Xmaxnm (log €),CHCI3: 369 (2.76). IR vso: 1125, 1109 cm-1, which agree well with those reportedpreviously [172(c)] for cis-RuBr2(TMS0)4. No other spectroscopic data are availableas crystals of the trans isomer were obtained following a recrystallization step(Et0H/acetone; 1:10 v/v); see below, Section Trans-RuBr2(TMS0)4The recrystallization of cis-RuBr2(TMS0)4 (described in Section 2.4.8) resultedin a cis to trans isomerization of the complex, and orange crystals of trans-RuBr2(TMS0)4, suitable for X-ray crystallography, were deposited from theEt0H/acetone solution. Anal. calc. for C16H32Br204RuS4: C, 28.36; H, 4.76. Found:C, 28.53; H, 4.81%. Xmaxnm (log c), CH2C12: 455 (2.31). IR uso: 1107, 1055 cm-1.1H NMR (300 MHz, CD2C12): S 2.25 (2H, m, 0-protons); 3.10, 4.00 (each 1H, m,a-protons). The spectroscopic data agree well with those previously reported [172(c)]for the trans-complex except for the 1H NMR data which were previously unreported.2.4.10 Ru2C15(Et2S0)4A solution of diethylsulfoxide (0.43 mL, 4 mmol) in Me0H (10 mL) was added51to a 20 mL reaction mixture of the "ruthenium-blue" solutions (see Section 2.4.1), andthe reaction mixture refluxed for 6 h under H2. The resulting dark brown-orangesolution was filtered while still hot and reduced to a volume of approximately 8 mL byvacuum; dry ether (40 mL) was then added slowly to the concentrated solution whichbecame cloudy. This solution was filtered under Ar and set aside. The complexprecipitated slowly over a few days from the filtrate, sometimes as a fine crystallinematerial and at other times as fine flakes. Yield: 45%. The complex was collected underAr, dried in vacuo at room temperature and stored under an atmosphere of Ar. Anal.calc. for C16H40C1504Ru2S4: C, 23.89; H, 4.98; Cl, 22.08. Found: C, 23.89; H,4.98; Cl, 21.85%. Xmaxnm (log 6), CH2C12: 351 (3.34); 455 (2.92). IR uso: 1071, 326cm-1. 1H NMR (300 MHz, CDC13): (5 1.41 (br t, CH3); 2.86 (br s, CH2).Am(CH3NO2, 7.8 x 10-3 mol/L): 4.68 ohm 1 mol-1 cm2. Mol. Wt. (calc. Mol. Wt.):836.4 (803.7) g mol-1. /Leff = 0.81 BM. Mass spectrum (El and FAB): no parentpeaks were found, and the only peaks seen in the FAB spectrum were due to the matrixor free Et2S0.2.4.11 [H(nPr2S0)2]+ [trans-RuC14(nPr2S0)21-A solution of 11Pr2S0 (0.5 mL, 4 mmol) in Me0H (10 mL) was added to the"ruthenium-blue" solutions (20 mL) (see Section 2.4.1), and the reaction mixturerefluxed under an atmosphere of H2 for 6 h. The resulting dark-orange solution wasfiltered, and the volume of the solution reduced (8 mL). Dry ether (65 mL) was addedslowly to the reduced reaction mixture, and the ether solution filtered and set aside. A52fine orange precipitate was deposited on the sides of the flask after a few days and wascollected under Ar. Yield: 45%. Crystals suitable for X-ray analysis were obtained fromthe remaining filtrate after a few months. Anal. calc. for C24H52C1404RuS4: C, 36.92;H, 7.31. Found: C, 36.99; H, 7.38%. Xmaxnm (log e), CH2C12: 374 (3.38); 420(2.87). IR uso: 1093, 1015 cm 1; VoHo: 1600-1100 br, 734 cm-1. 1H NMR (300 MHz,CD2C12): Broad and featureless. Am (CH3NO2, 1.03 x 10-3 mol/L): 7.69 ohm-1 mol-1^2cm .2.4.12 Ru2C15(nPr2S0)5RuC13.3H20 (0.25 g, 1 mmol) was dissolved in a minimum amount of nPr2S0(4 mL) and the reaction solution stirred overnight in air. Acetone (100 mL) was addedto the reaction mixture, and the resulting clear orange solution set aside. After a fewmonths, fine yellow crystals were deposited on the sides of the vessel which werecollected and dried in vacuo at 70°C. A fine yellow powder also precipitated after a fewdays from the remaining filtrate which was kept at 0°C. Yield: 55%. Anal. calc. forC39H70C1505Ru2S5: C, 34.40 H, 6.67; Cl, 16.91. Found: C, 34.23; H, 6.67; Cl17.06%. Xmaxnm (log E), CH2C12: 372 (3.32). IR: 1093, 1014, 391, 289, 283 cm-1.1H NMR (300 MHz, CD2C12): (5 1.05, 1.15 (br t, 30H, CH3); 1.70, 1.97, 3.34 (br t,total 24H, -CH2CH2-, CH2-S); 3.34, 4.15 (br m, total 17 H, CH2-S). Mol. Wt. (calc.Mol. Wt.): 1112 (1049.7) g/mol. Mass spectrum (El, FAB): no parent peaks werefound; the only peaks found in the FAB spectrum were from the matrix used in thedetermination and free nPr2S0.532.4.13 Ru2C15(n13u2S0)5RuC13.3H20 (0.13 g, 0.5 mmol) was refluxed in 20 mL Me0H under anatmosphere of H2 to obtain the "ruthenium blue" solutions as described previously(Section 2.4.1). Di(nbutyl)sulfoxide (0.5 mL, 3 mmol) dissolved in Me0H (5 mL) wasadded to the "ruthenium blue" solutions, and the reaction mixture refluxed under H2 fora further 6 h. The resulting yellow/green solution was filtered, and the volume of thereaction mixture reduced to about 8-10 mL. Dry ether (50 mL) was added dropwise tothe concentrated reaction solution, and the solution refiltered and set aside at 0°C for4-5 days. The yellow complex which precipitated was collected and dried in vacuo at70°C. Yield: 55%. Anal. calc. for C40H90C1505Ru2S5: C, 40.35; H, 7.65; Cl, 14.92.Found: C, 40.26; H, 7.64; Cl 15.25%. Xmaxnm (log e), CH2C12: 372 (3.14). IR uso:1107, 1022 cm-1. 1H NMR (300 MHz, CD2C12): .5 1.0 (t, 30H, CH3); 1.50, 1.72,1.90, 2.75 (br, complex m, total 47H); 3.42, 4.15 (br td, 6H each, Ru-S-CHH'). Mol.Wt. (Calc. Mol. Wt.): 1075 (1189.7) g mol-1. 'Leff = 2.86 BM. Mass spectrum (El,FAB): no parent peaks were found in the mass spectrum; only peaks due to the matrixand the free ligand were observed.2.4.14 fRuC12(MePhS0)2lnRuC13.3H20 (0.31 g, 1.18 mmol) in Me0H (10 mL) was refluxed in anatmosphere of H2 until the solution became dark blue (approx. 4 h). MePhS0 (1.0 mL,7.14 mmol), dissolved in Me0H (10 mL), was added to the blue solution, and the54reaction mixture refluxed under H2 for a further 4 h. The complex formed after 1 h,precipitating as a fine yellow powder. The mixture was filtered while hot, and thecomplex was collected and dried at 70°C under vacuum. Yield: 70%. Attempts toextract more of the complex from the filtrate were unsuccessful. Anal. calc. forC14H16C1202RuS2: C, 37.17; H, 3.56. Found: C, 37.23; H, 3.73%. Xmaxnm (log 6),CH2C12: 358 (2.64); 437 (2.23). IR v50: 1124 cm-1. 1H NMR (300 MHz, CD2C12):6 2.66 (s, 3H, CH3 free MePhS0), 2.80 (s, 3H, 0-bonded CH3 ); 3.20, 3.22, 3.70,3.79 (s, total 14H, CH3 of S-bonded MePhS0); 6.98, 7.05, 7.45, 7.70, 7.85(overlapping m, 30H, phenyl protons of MePhS0).2.4.15 RuC13(Ph2S0)2 and mer-RuC13(Ph2S0)2(CH3OH)A solution of RuC13.3H20 (0.25 g, 1 mmol) in Me0H (20 mL) was refluxedunder H2 for 4 h when the solution turned a deep blue. Diphenylsulfoxide (0.8 g, 4mmol), previously dissolved in Me0H (10 mL), was added to the "ruthenium-blue"solutions, and the mixture refluxed for a further 6 h. The resulting dark-orange solutionwas filtered under Ar, and the volume of the filtrate reduced until the reaction solutionbecame oily (8 mL). Dry and degassed ether (60 mL) was added to the reactionsolution, and the resulting clear orange-brown "solution" set aside for 3-5 days at 0°C.Crystals suitable for X-ray analysis formed on the side of the flask and were collectedby filtration. The filtrate was left for several days and a fine orange powderprecipitated; this was collected and dried in vacuo at room temperature. Yield: 45%.Data for the precipitated complex, RuC13(Ph250)2: Anal. calc. for55C24H20C1302RuS2: C, 47.08; H, 3.27; Cl, 17.41. Found: C, 46.97; H, 3.27; Cl,16.88%. Xmaxnm (log €), CH2C12: 375 (3.43); 450 (3.30). IR uso: 1086, 943 cm4.1H NMR (300 MHz, CD2C12): 6 7.64, 7.45 (br d).Spectral data for the crystals of RuC13(Ph2S0)2(Me0H): Xmaxnm (log e),CH2C12: 375 (3.26); 450 (3.10). IR u: 3420, 1085, 1045 cm1. 1H NMR (300 MHz,CD2C12): 6 7.68, 7.47 (br d); 3.42 (s, CH3 of Me0H).2.5 The Synthesis of the Chelating Sulfoxide Complexes of Ruthenium2.5.1 Trans-RuC12(BMSE)2RuC13.3H20 (0.27g, 1 mmol) was refluxed in Me0H (20 mL) in an atmosphereof H2 until the solution became dark blue (approx. 4 h). A solution of 1,2-bis(methylsulfinyl)ethane (0.38 g, 2.5 mmol) in Me0H (10 mL) was added to theresulting blue solution (Section 2.4.1). Refluxing was continued under H2 for a further4 h. The complex formed after 1 h, precipitating as a fine, light green powder. Thereaction mixture was filtered while hot, and the collected precipitate dried at 70°Cunder vacuum. Yield: 80%. Attempts to extract more of the complex from the filtratewere unsuccessful. Anal. calc. for C8H20C1204RuS4: C, 19.99; H, 4.17. Found: C,20.15; H, 4.26%. Xmaxnm (log c), H20: 376 (2.94); 301 (3.28). IR uso: 1109 cm1.1H NMR (300 MHz, D20) (5 3.25 (s, 6H, 2 x CH3); 3.85 (s, 4H, CH2CH2). Am(H20, 9.53 x 10-3 mol/L): 60.4 ohm-1 mol-1 cm2. Mass spectrum (EI) [m/z (relativeintensity)]: 480 (3.9) [M]+, 326 (1.9) [M - (CH3SOCH2)21+, 63 (100) [CH3S01-1-.Yellow crystals suitable for X-ray analysis were obtained from a saturated solution of56the complex in hot water which was left uncovered at room temperature for a few days.2.5.2 Cis-RuC12(BESE)2The procedure used was as described above in Section 2.5.1, except that the Ru-blue solution turned green within a few minutes of adding the sulfoxide, and thecomplex precipitated within an hour. The hot solution was filtered, and the light yellowprecipitate collected. Pale yellow crystals suitable for X-ray analysis formed in thefiltrate after it cooled to room temperature. Yield: 55%. Anal. calc. forC12H28C1204RuS4: C, 26.86; H, 5.22; S, 23.80. Found: C, 26.85; H, 5.22; S,23.66%. Xmaxnm (log 6), H20: 398 (3.06); 320 (3.23). IR uso: 1128 cm-1. 1H NMR(400 MHz, D20) (5 1.36, 1.55 (t, 12H, 4 x CH3); 3.30 (td, 2H, CHH'CHH'); 3.45 (m,2H, CH3CH2); 3.63 (m, 2H, CHH'CHH'); 3.70 (m, 4H, CH3CH2); 3.87 (m, 2H,CHH'CHH'); 3.93 (m, 2H, CH3CH2); 4.09 (dt, 2H, CHH'CHH'). Am(H20, 1.03 x10-3 mol/L): 33.9 ohm-1 mol-1 cm2. Mass Spectrum [m/z (relative intensity)]: 536(5.0) [M]+, 354 (1.9) [M - (CH3CH2S(0)CH2)2]+, 77 (100) [CH3CH2S0]+.2.5.3 Trans-RuC12(BPSE)2The procedure was as described in Section 2.5.1 except the Ru-blue solutionturned green within a few minutes of adding the sulfoxide and the complex precipitatedwithin an hour. The hot solution was filtered and the light yellow precipitate collected.The filtrate was kept at 0°C and more complex precipitated after a few days. Yield:47%. Anal. calc. for C16H36C1204RuS4: C, 32.43; H, 6.08; S, 21.62. Found: C,5732.41; H, 6.09; S, 21.53%. Xmaxnm (log E), H20: 395 (3.04); 320 (3.26). IR uso:1128 cm-1. 1H NMR (300 MHz, CD2C12): (5 1.10 (t, 12H total, 4 x CH3); 1.83, 2.20(m, 4H each, 2 x CH3CH2CH2S(0)); 3.40, 3.70 (m, 8H each, 2 x CLI2(SO)Cf_12).Am(H20, 1.14 x 10-3 mol/L): 42.7 ohm-1 mo1-1 cm2. Mass spectrum, El [m/z(relative intensity)]: 592 (2.2) [M]+; 382 (0.6) [M - (CH3CH2CH2SOCH2)2]+; 41(100) [CH2CHCH2]+. Bright yellow crystals suitable for X-ray analysis were grownovernight in a saturated Me0H solution of the complex.2.5.4 Cis-RuCl2(BMSP)2The procedure was as described in Section 2.5.1 except the Ru-blue solutionturned green within a few minutes of adding the sulfoxide and the complex precipitatedwithin an hour. The hot solution was filtered and the light yellow precipitate collected.Yield: 65%. Further attempts to isolate more complex from the filtrate wereunsuccessful. Anal. calc. for C10H24C1204RuS4: C, 23.62; H, 4.72; Cl, 13.97.Found: C, 23.81; H, 4.78; Cl, 13.69%. Xmaxnm (log E), H20: 336 (2.97); 298 (2.90).IR uso: 1085 cm-1. 1H NMR (400 MHz, CDC13): 45 2.20, 2.29 (m, 1H each,CH2CH2CH2); 3.41, 3.45 (s, 3H each, CH3); 3.68, 4.05 (m, 2H each, CLI2CH2CH2).Am(H20, 9.97 x 10-3 mol/L): 12.6 ohm-1 mo1-1 cm2. Mass spectrum, El [m/z(relative intensity)]: 508 (0.5) [le-, 153 (8.4) [CH3S(0)(CH2)3S(0)CH3J+, 41(100)[CH2CHCH2]+ . Crystals suitable for X-ray analysis were grown in a saturated solutionof the complex in Me0H.58Chapter 3: The Structural Properties of Sulfoxides; RutheniumComplexes of DMSO and TMSO3.1 General IntroductionSulfoxides have been recognised as Lewis bases since 1907 [through 104(a)] butwere largely ignored as ligands in coordination chemistry until the 1960s, when reportson the synthesis and magnetic properties of DMSO complexes of Pd, Co, Ni and Feappeared [147]. Since that time, an enormous body of work on the coordinationchemistry of sulfoxides has appeared in the literature, and has been admirablysummarized at least up to about 1980 [104]. Sulfoxides are of interest in syntheticchemistry due to the excellent solvating properties of the lower sulfoxides, the potentialfor chirality at the sulfur and the ambidentate nature of the sulfoxides as ligands.Dimethyl sulfoxide (DMSO) is the first member of the homologous series ofsulfoxides and, in addition to its use as a solvent and ligand in coordination chemistry,is also used in some medical applications [104(b)] (e.g. as a diuretic or penetrantcarrier). The structure and bonding properties of sulfoxides are discussed in Section 3.2.DMSO is used as an example for two reasons. DMSO has been studied extensively (seefor example, ref. 104(b)), and its properties can be extended, in most cases, to thehigher sulfoxides. The structural properties of sulfoxides are discussed in Sections 3.2 -3.6, and the structural and spectroscopic details for Ru complexes of DMSO and TMSOare discussed in the later half of the chapter (see Section 3.7)593.2 Structural Properties of SulfoxidesThe sulfur in sulfoxides is sp3 hybridized [148], and the molecule ispyramidal in shape with S at the apex. A non-bonding pair of electrons completes the"tetrahedron". Figure 3.1 shows the structure of dimethylsulfoxide [104(b)], andselected bond lengths and angles from different structural determinations aresummarized in Table 3.1 (adapted from refs. 104(a) & 149).Figure 3.1 The structure ofDMSOThe bond angles within free DMSO (Table 3.1) suggest that the geometry ofthe molecule at the sulfur is approximately tetrahedral although the average C-S-0(107°) and C-S-C (98°) angles deviate from the expected angle of 109° for tetrahedralconfigurations; the deviation is due to the lone pair of electrons on S and the presenceof some double bond character in the S-0 bond which force the C-S-C bond anglescloser together [150].The length of a single S-0 bond has been estimated by calculation to be about1.6 A [151] but structural determinations of DMSO done in the solid and gas phaseindicate that the S-0 bond length is shorter (1.47 to 1.531 A), which implies that some60double bond character is present. Based on the data in the literature, however, thedegree of double bond character in the SO unit cannot be quantified. For the purposesof later discussion, the S-0 bond length of 1.531 A [149(c)], determined in the solidstate at 5°C, is used as this temperature is closest to the temperatures at which othermetal-sulfoxide structural determinations have been done.Table 3.1 Selected Bond Lengths for DMSO in the Solid and Gas PhaseBond Lengths (A) Bond Angles (°)State S-0 C-S C-S-C C-S-0 Ref.Gaseous 1.47 1.82 100 + 5 107 + 5 149(a)Gaseous 1.477 1.810 96.38 106.71 149(b)Solid 1.531 1.821 97.4 106.8 149(c)at 5°C 1.775 106.7Solid 1.471 1.812 97.86 107.04 149(d)at -60°C 1.801 107.43The crystal structures of Ph250 [152] and TMSO [153] are also known,and both sulfoxides are approximately pyramidal with S-0 bond lengths of 1.47 and1.527 A, respectively, again indicating the presence of some double bond character inthe S-0 unit of both sulfoxides.3.3 Sulfoxide-Metal BondingSulfoxides are ambidentate ligands and can coordinate to a metal either throughS or 0. This was recognized early in the 1960s (see ref. 104(b) for examples), and it61was observed initially that DMSO coordinated to "harder" metals via the oxygen andto "softer" metals [154] through the sulfur. This behaviour is generally seen formost complexes of DMSO, examples of which can be found in ref. 104(b) whichreviews work done on metal-DMSO complexes up to the early 1970s. Exceptions to therule where sulfoxides bind to "softer" metals (e.g. Ru(II) and Pd(II)) via oxygen areknown. Such behaviour has been explained by a combination of steric and electronicfactors, and is described in Section 3.5Crystallographic determinations of a wide variety of metal-sulfoxide complexesin the literature have been summarized, and the data to about 1980 collated by Davies[104(a)]. The effects on the sulfoxide upon coordination to the metal are described ingreat detail in ref. 104(a), and only the salient points are presented below (Sections3.3.1 - 3.6.2). The purpose of these sections is to provide the reader with a frameworkfor understanding the "changes" in the sulfoxide moiety that result from coordinationto the metal centre, and is not intended to provide a detailed description of existingsulfoxide-metal complexes.3.3.1 S-Bonded Sulfoxide-Metal ComplexesTable 3.2 contains selected structural data for some metal-DMSO complexesreported in the literature and can be used to highlight the changes that occur in thestructure of sulfoxides upon coordination to a metal centre. The geometries of the S-bonded DMSO ligands within the various complexes in Table 3.2 remain essentially thesame as that of the free ligand. The average C-S-0 bond angles for the coordinated62sulfoxide, 108° (Table 3.2), are close to that of the free ligand, 107° (Table 3.1). Theeffects of coordination are most evident in the SO unit; the average S-0 bond length offree DMSO decreases significantly (1.531 to 1.476 A, see Table 3.1 and Table 3.2).Table 3.2 Some Structural Data for Selected Transition Metal-DMSO ComplexesComplex S-0 Bond (A) C-S-0 Angles (°)S-bonded 0-bonded S-bonded 0-bonded Ref.mer-Rh(Py)2C13(DMa0) 1.481 109.3 155cis-PtC12(DMS0)2 1.462 108.6 156cis-RuC12(DMS0)3(DMS0) 1.485 1.557(4) 106.6 103 107mer-RuC13(DMa0)2(DMS.0) 1.48 1.545 108 103(1) 157trans-FeC12(DMS(2)4+ 1.541 102 158trans-CuC12(DMS0)2 1.531(4) 103.6 1593.3.2 0-bonded Sulfoxide-Metal ComplexesThe structural data for the 0-bonded DMSO ligands within the complexes(Table 3.2) also indicate that the geometry of the free sulfoxide hardly changes uponcoordination to the metal centre. The average C-S-0 bond angles (104°) are slightlydiminished but are still close to the value of 107° in free DMSO (Table 3.1.), whichindicates that the ligand still retains its "tetrahedral" geometry despite coordination tothe metal.The S-0 bond length in 0-bonded sulfoxides remains virtually unchanged; forexample, the S-0 bond within the complexes in Table 3.2 are comparable to that of free63DMSO (1.531 - 1.557 A vs. 1.531 A, respectively). In general, the S-0 bond lengthin 0-bonded sulfoxides undergoes small changes either decreasing or increasing inlength slightly [104(a)].3.4 A Bonding Model for Sulfoxide-Metal ComplexesA simple valence-bond rationale can be used to explain the ambidentate bondingnature of sulfoxides. The structure of the sulfoxide is considered to be a hybrid of thethree resonance forms indicated in Figure 3.2, while resonance form II is normally usedto depict a sulfoxide [104(a)]. X-ray spectroscopy studies on sulfoxides [160,161],however, indicate that the S-0 moiety is polarized, and that the sulfur has a net positivecharge [162]. Resonance form I is therefore probably a more accurate representationof sulfoxides than form II, and coordination to Lewis acids is more likely through theoxygen. Examples of 0-bonded sulfoxide complexes are common (see ref. 104(b) forexamples). Transfer of electron density from the negative oxygen to the metal is notexpected to affect much the positive charge on the sulfur [104(a)].The 0-bonded DMSO ligands within the complexes in Table 3.2 have M-0-Sbond angles in the 120° range (120.0(2)° [107], 124.5(4)° [158] and 118.2(2)° [159]for the Ru, Fe and Cu DMSO complexes, respectively) which is indicative of trigonalplanar geometries. The oxygen atom within the S±-0- form can thus be considered sp2hybridized; overlap of one oxygen sp2 orbital with an sp3 hybridized S atom results ina single S-0 a bond which leaves two sp2 lone pairs on the oxygen for coordination tothe metal [104].64RN't. .-.^R\ .. ..^R\ .-. :I-.S-0: S=0 Sr----0R/ .•^R/ .. R/Figure 3.2 The three resonance forms for sulfoxidesThe interaction between the remaining lone-pair p-orbital of oxygen and thevacant d-orbitals of S (pt.- d7 overlap) is therefore not affected directly by thecoordination environment of the oxygen. Coordination to a weak Lewis acid would havea small effect on the r overlap while coordination to a strong Lewis acid woulddecrease the measure of overlap, leading to a smaller decrease in the S-0 bond length.The structural data are in keeping with this reasoning; the S-0 bond lengths for 0-bonded DMSO in the Ru, Fe and Cu complexes in Table 3.2 lie in the range from1.531 A - 1.557 A which is comparable with that of free DMSO (1.531 A, Table 3.1,p.61).As the best representation of the free sulfoxide molecule is resonance form I, itis perhaps surprising that bonding occurs at all through the positively charged S.Donation from resonance form III could account for S-bonding of sulfoxides, but X-rayKa spectral studies [162] on the sulfur of sulfoxides indicate that the S becomes morepositive (relative to the free ligand) upon coordination [1621 A bonding model in whichdonation from form III is included would tend to generate a neutral S atom.65Donation from form II, however, leaves a positive charge on the sulfur and ismore consistent with X-ray Ka absorption spectral data reported in the literature [160-162]. With donation from resonance form II, the S-0 bond order is closer to two thanthree, in keeping with the S-0 bond lengths determined within S-bonded sulfoxidecomplexes (e.g. Table 3.2, p.63, and ref. 104(a)).The M-S-0 bond angles for the S-bonded complexes tabulated in Table 3.2 rangefrom 112° to 115°, showing that the geometry around S is a distorted tetrahedral. Thissuggests that the S is sp3 hybridized, and so overlap with an sp hybridized 0 leaves twofilled p-orbitals on the oxygen available for overlap with the d-orbitals of S (pr-d7overlap) [104(a)].The S-0 bond environment is directly affected by coordination of the sulfoxideto the metal through S, as an sp3 orbital of S is involved in the S-metal bond. Donationof electron density from 0 to S through pir- d2. overlap compensates for depletion ofelectron density at the sulfur due to coordination of the sulfoxide to the metal [104(a)],and results in an increase in the S-0 bond order, and thus a decrease in the S-0 bondlength, as observed (see for example, S-0 bond lengths for coordinated DMSO inTable 3.2, p.63, vs. that for free DMSO in Table 3.1, p.61).Valence bond arguments which utilize the different resonance forms of the freesulfoxides are adequate in explaining much of the structural data determined for metal-DMSO complexes shown in Table 3.2, and can be extended to other sulfoxide-metalcomplexes. Rationalizations of this kind also encompass the initial empiricalobservations that coordination of sulfoxides occurred with "softer" metals via S and via66O with "harder"4 metals. Metal-ligand orbital overlap with "hard" acids is morefavourable with the less diffuse (and therefore "hard") donor orbitals of oxygen, while"soft" acids have better orbital overlap with the more diffuse donor orbitals of S[104(a),154].3.5 Electronic and Steric EffectsReports of metal-sulfoxide complexes where the sulfoxide coordinates to "softer"metals via oxygen have appeared in the literature. Examples include cis-RuC12(DMS_O)3(DMS0) [107], cis-[Pd(DMS0)2(DMS0)2]2+ [163] andPd(Ph2PCH2CH2PPh2)2(DMS0)2+ [164]. Electronic and steric factors have beeninvoked to rationalize such findings.The choice of coordination atom in ambidentate ligands in metal complexes withmixed ligand systems is determined in part by the ability of other ligands on the metalcentre to compete with the ambidentate ligand for electron density [165]. Thepresence of stronger 7-electron acceptors on the metal withdraws electron density fromthe metal, and causes "softer" metals to become "harder". The reduction in electrondensity may be accompanied by a change in coordination of the ambidentate ligandthrough the "soft" to the "hard" donor atom to optimize orbital overlap [165].Steric constraints are, however, another reason for the coordination of sulfoxidesthrough 0 to "softer" metals in some metal-sulfoxide systems. Coordination of4 The "hardness" or "softness" of a metal is a qualitative indication of the degreeof diffuseness and size of its atomic orbitals. The more diffuse and the larger theorbital, the "softer" the metal is. See ref. [154] for more details.67sulfoxides through 0 is less sterically demanding than through S [164]. In the complex,Pd(Ph2PCH2CH2PPh2)2(DMSQ)2+ [164], the diphosphine ligand has a cone angle of125° [166] which makes coordination via S extremely hindered. As a result, theDMSO is forced to coordinate through 0 to relieve steric strain. A similar argument hasbeen made for cis-[Pd(diisoamylsulfoxide)4]2+ [167], where the bulky substituentson the sulfur force coordination of the sulfoxide via 0 rather than S.The valence bond arguments presented in Section 3.4 account for most of theobserved changes in DMSO (and by extrapolation, to other sulfoxides) uponcoordination to the metal centre. Steric constraints and some electronic considerationsalso play a role in determining whether sulfoxides coordinate through S or 0. Theempirical observation that S and 0 coordinate to "softer" and "harder" metals,respectively, is a useful guide, but steric and other electronic considerations should alsobe considered in a discussion of the ambidentate nature of sulfoxide bonding.3.6 NMR and IR SpectroscopyThe presence of S- or 0-bonded sulfoxides in metal-sulfoxide complexes cangenerally be detected using these two routine spectroscopic methods.3.6.1 1H NMR and 13C NMR SpectroscopyThe 1H NMR and 13C(11-1) chemical shifts of especially the a-protons of thefree sulfoxide change upon coordination of the sulfoxide to the metal and can indicatethe presence of either S- or 0-bonding. The resonance peaks in the 1H NMR spectra68of free sulfoxides generally shift downfield when the sulfoxide is coordinated to a metalcentre. The magnitude of the shift depends on the coordination mode; larger effects areobserved upon coordination through S than through 0. Free DMSO, for example, hasa single resonance in the 1H NMR spectrum due to equivalent methyls at (52.62 ppmrelative to TMS in CDC13 [108]. In cis-RuC12(DMS0)3(DMSQ), the resonance due tothe methyls of 0-bonded DMSO is shifted downfield to (52.75 ppm, and the resonancesdue to the methyls of S-bonded DMSOs are shifted further downfield and fall within therange (5 3.00 - 3.52 ppm [108].In general, 0-bonding of sulfoxides results in small chemical shifts ( __0.5 ppm)of the a-protons while larger shifts of around 1 ppm are seen for coordination throughsulfur; the same phenomenon is observed for 13- and 7-protons although the magnitudeof the effects decreases as the protons become further removed from the sulfur [104(a)].In the bonding model discussed in Section 3.4 (p.64), coordination of thesulfoxide via 0 occurs through the sp2 orbitals of 0, and thus the electron density inthe C-S bond, which involves sp3 orbitals from S, is only affected to a small degree.The a-protons are thus only deshielded to a small degree which is reflected in thesmaller downfield shift observed in the 1H NMR spectra. In contrast, coordinationthrough S involves the sp3 orbitals of S which results in direct withdrawal of electrondensity from the C-S bond, and thus the exertion of a greater deshielding effect on thea-protons. The result is a larger downfield shift for the a-protons of S-bondedsulfoxides.The inequivalence of diastereomeric a-protons in the 1H NMR spectra of a free69sulfoxide increases when the sulfoxide is S-bonded, while the converse is found for 0-bonded sulfoxides. This effect has been observed for the diastereomeric protons ofdiethylsulfoxide [168]. Coordination of diethylsulfoxide via oxygen decreases thedegree of inequivalence and simplifies the proton NMR spectrum, while coordinationthrough S increases the inequivalence of the a-protons [144Similar effects are found in 13C{1H) NMR spectra of sulfoxides for the samereasons. The a-carbons of free sulfoxides are found further downfield than the 13-carbons, and when coordinated to metal through S shift even further downfield due todeshielding by the metal [172(c)]. The use of 13C{1H) NMR spectroscopy inconjunction with the proton spectra of cis-RuC12(TMS0)4 was particularly useful in theassignment of the a- and 0-protons of the free and coordinated ligand (Section 3.9.1(a)).3.6.2 Infrared SpectroscopyThe effects on the SO stretching frequency of sulfoxides upon coordination toa metal centre parallel those found in the proton NMR. A greater shift in the SOstretching frequency is observed in S-bonded than in 0-bonded sulfoxides. The changesin the SO infrared stretching frequencies are a useful indication of S- or 0- bondedsulfoxides, and examples of complexes with S-, 0- and both types of bonded sulfoxideswith their respective 1,50 assignments are tabulated in Table 3.3.Coordination of sulfoxides via S results in a shorter S-0 bond due to donationof electron density from 0 to compensate for the withdrawal of electron density fromS by the metal (see Section 3.4, p.64). The reduction in the S-0 bond length is70Table 3.3 The SO Stretching Frequencies of Some 0- and S-Bonded Ru-SulfoxideComplexesComplex(uso free ligand)Ref.S-bonded^0-bondedcis-RuC12(DM50)3(DMSQ)(1055)cis-RuBr2(DM50)3(DMSQ)(1055)trans-RuC12(DM50)4(1055)trans-RuBr2(DM50)4(1055)cis-RuC12(TM50)4(1020)trans-RuBr2(TN/150)4(1020)mer-RuC13(DMS0)2(DMSQ)(1055)transtRuC14(Pr250)2F(1015)[(Pr2S0)2F1]+(1015)1115^960^107,1081111.5^924^1241086^ 121,1241082^ 175^1064,1121^ twa,b,172(c)1107,1055^ twa1127,1107^912^1571093 twa1015RuC13(Ph2S0)(Ph2S_Q)(Me0H)^1085^1045^twa(1045)a tw = this work.b Published in ref. 171(a).71manifested as an increase in the SO stretching frequency, compared to that of the freeligand. In the case of 0-bonded sulfoxides, donation of electron density occurs throughan sp2 orbital of the oxygen, and smaller effects are exerted on the S-0 bond. As aconsequence, the SO stretching frequency is less affected, and only small shifts in theSO infrared stretching frequency are observed when the sulfoxide is coordinated via 0.The resulting changes in the structure of the sulfoxide upon coordination to ametal centre, discussed in the preceding sections, are general and can be applied to theruthenium-sulfoxide systems discussed in Chapters 3 and 4.3.7 Monodentate Sulfoxide Complexes of Ru(II) and Ru(III)The variety of Ru-sulfoxide complexes that were isolated, with only minorstructural changes in the sulfoxides and in reaction conditions, was perhaps the mostsurprising aspect of this project. Reports in the literature on ruthenium-sulfoxides aresummarized briefly in Section 1.11, the majority being on complexes of DMSO. Indeed,the first known ruthenium-sulfoxide complexes, reported in 1971, were cis-RuC12(DMS0)4 and trans-RuBr2(TMS0)4 which originated from studies by this group[106]. These two complexes marked the beginning of a substantial amount of work thathas been done since on various ruthenium sulfoxide complexes. Areas of researchinclude the study of ruthenium-sulfoxide complexes as catalysts for homogeneoushydrogenation of olefins [109-112], as catalysts for the oxidation of sulfides[169,170], as precursors to metal-nitroimidazole radiosensitizers [49], and as anti-cancer agents in their own right [124,125,127,132,134].720 0II^ II*R/S* S\1 \R*S = chiral siteIn addition to the ambidentate nature of sulfoxides (see Section 3.2. p.60),sulfoxides can also possess chiral centres at the sulfur when the substituents aredifferent. In the case of the chelating sulfoxides, there are two chiral sulfurs present (seeFigure 3.3). That the chemistry of ruthenium sulfoxide complexes is so rich and variedis then scarcely surprising, and is reflected in the variety of complexes obtained in thepresent work.Figure 3.3 Chirality within sulfoxidesThe complexes synthesized and characterized during the course of this work, aswell as some examples culled from the literature, are summarized in Table 3.4. Thecomplexes are, for the most part, discussed individually although where appropriatesome are discussed together to highlight common features within the respectivestructures. Recent reports, including those from this thesis work[121,157,171,172], have appeared in the literature indicating the complexity of73ruthenium sulfoxide chemistry, and relevant details from these reports are incorporatedin the discussion to provide a more comprehensive account of this field of chemistry.This part of Chapter 3 deals specifically with ruthenium complexes of DMSO andTMSO; complexes of other monodentate sulfoxides and of chelating sulfoxides arediscussed in Chapter 4.The crystal structures of the complexes determined during the course of thisproject were solved by Dr. S. J. Rettig of this department, and all related figures anddata are reproduced with his permission. Where crystal structures of the synthesizedcomplexes have been determined, selected data are tabulated and discussed in the text.Full experimental details are available in Appendix D; structure factor tables are notincluded.3.8 DMSO Complexes of RutheniumSince the first report on the synthesis of RuC12(DMS0)4 and RuBr2(DMS0)4appeared in the literature [106], a number of other Ru-DMSO complexes have beenreported [107-110,117-121,124,157,175]; related compounds [172(a) & (c)] includingthe synthesis of Ru(III)/DMS complexes [121] have also appeared in the literature. Inaddition, the Trieste group has studied the selective oxidation of thioethers to sulfoxideswith molecular oxygen using Ru(III)-DMS0 complexes as catalysts [170], while Riley'sgroup studied the potential of the Ru(II)-dihalo-dimethylsulfoxide complexes as catalystsin similar oxidations [169] and found that the dibromo complexes had greater catalyticactivity than the dichloro analogues [169(c)].74Table 3.4 Examples of Ruthenium-Sulfoxide Complexes Reported in the Literatureand From this Present WorkSulfoxide^ Complex^ Ref.DMSO cis-RuX2(DMS0)4a^107,124trans-RuX2(DMS0)4a 121,124Ru2C14(DMS0)5^114-116,twbRu2C16(DMS0)4 119(b),twbmer-RuC13(DMS0)3^157Et2S0^ Ru2C15(Et2S0)4^ twbnPr2S0^[H(nPr2S0)2]+[-RuC14(nPr2S0)21"^twbRu2C15(nPr2S0)5^ twbnBu2S0^ Ru2C15(nBu2S0)5^twbTMSO^ cis-RuC12(TMS0)4^172(c),twb,ctrans-RuBr2(TMS0)4 twbtwb,d[RuBr3(TMS0)4Li]2MePhS0^ [RuC12(MePhS0)2]fl^twbPh2S0 RuC13(Ph2S0)2(Me0H)^twba X = CI or Br.b tw = this work.C Published in ref. 171(a).d Published in ref. 171(b) & (c).75The diversity of the structures found within the reported complexes is startling.Several formulations of the complexes in the majority of the earlier reports were basedsolely on elemental analysis and infrared data, and have been shown subsequently to beincorrect. Some of the published procedures [119] have been repeated, and differentresults were obtained [121,172(a)]. There were few structural reports up to the late1970s, while, in more recent publications, crystal structures have been indispensable indefining the structures and geometries of the complexes. The chemistry of Ru-DMSOcomplexes is more intricate than first appears, and only now are the more subtle detailsof the field becoming clear.3.8.1 Cis-RuX2(DMS0)4, X = CI or Br3.8.1(a) Cis-RuC12(DMS0)3(DMS0)The synthesis [106,108], crystal structure [107,124] and anti-tumour activity[103,124] of cis-RuC12(DMS0)4 have been reported elsewhere, and the details of itsanti-tumour activity and synthesis summarized in Chapters 1 and 2, respectively.Discussion of this complex in conjunction with other Ru-sulfoxide complexes providesboth a reference point and a basis for comparison of various properties of thecomplexes, and thus relevant details pertaining to cis-RuC12(DMS0)4 are included inthis chapter.The significance of cis-RuC12(DMS0)4 in the field of ruthenium sulfoxidechemistry is considerable. This single compound marked the debut of rutheniumsulfoxide chemistry, a new field of chemistry that encompasses catalysis, and medically76oriented research. In addition, cis-RuC12(DMS0)4 has also been used as a precursor toother Ru-DMSO [110,124] and Ru-sulfoxide complexes [172(c)], and a very wide rangeof other Ru(II) complexes [108,173,174]. Studies on the compound's anti-tumouractivity have also appeared [124,125,127], while cell accumulation data, obtained aspart of this work, are addressed in more detail in Chapter 5.In the context of this thesis, cis-RuC12(DMS0)4 is of interest because itpossesses anti-tumour activity [124], and also because the compound is the first knownexample of a Ru-sulfoxide complex containing both 0- and S-bonded sulfoxides[106,107]. Ruthenium (II) is considered a "softer" metal [154], and coordination ofDMSO through the sulfur would be expected; the presence of one 0-bonded DMSO (a"soft-hard" interaction) in the complex has been rationalized by steric arguments[107,108].The behaviour of this complex in solution has been studied [108], and thecomplex is known to lose some 0-bonded DMSO quickly; in CH2C12 solution, thereare thus two Ru(II) species (RuC12(DMS0)3(DMS0) and RuC12(DMS0)3(Solv))present in addition to the dissociated DMSO. In the proton NMR spectrum of thecomplex, the free ligand is seen at (5 2.62 ppm, and the remaining 0-bonded sulfoxideshave a resonance at (5 2.75 ppm, consistent with the small downfield shift of 0-bondedsulfoxides; the resonances for the remaining S-bonded sulfoxides are shifted furtherdownfield by about 0.9 ppm again as expected (see Section 3.6.1, p.68). A detailedanalysis of the peaks in the 1H NMR spectrum of this complex has been done [108] andis not reproduced here.77The SO stretching frequency region of cis-RuC12(DMS0)4 has also beenstudied, and comparisons with the deuterated analogue have confirmed the SO bondassignments [108]. The u for free DMSO (1055 cm-1) increases uponcoordination to Ru through S (1115 cm-1) while the converse is seen for coordinationvia 0 (960 cm-1) [108]. These shifts in the infrared spectra are reflected in the S-0bond lengths [107]; those of the S-bonded ligands decrease while that of the 0-bondedDMSO increases slightly relative to the S-0 distance of free DMSO (Table 3.1, p.61and Table 3.2, p.63).There are several synthetic routes for preparing cis-RuC12(DMS0)4; workers inthis laboratory heated a solution of RuC13.3H20 in DMSO under a hydrogenatmosphere at 80°C [106], and also used the "ruthenium-blue" (Section 2.4.1, p.45)solutions to obtain the complex [50]. Evans et al. reported [108] a modification of thefirst method, and simply refluxed a solution of RuCl3.3H20 in DMSO in air for severalminutes to obtain the complex in almost quantitative yield.3.8.1(b) Cis-RuBr2(DIVIS0)3(DMS.0)The bromo analogue, cis-RuBr2(DMS0)3(DMS0), was prepared by a trans tocis isomerization of trans-RuBr2(DMS0)4 [106,175] (see also Section 3.8.2(b)) in hotDMSO (150°C, 10 min); the crystal structure was determined, and the anti-tumouractivity of the complex evaluated in vivo [124]. Prior to the structural determination ofcis-RuBr2(DMS0)4 [124], a report on the preparation and isolation of two forms ofRuBr2(DMS0)4 appeared in the literature in 1978 [118]. Bora and Singh [118] had78refluxed an ethanolic solution of RuBr3.xH20 with DMSO, and isolated an orange (a)form of RuBr2(DMS0)4, while a yellow (0) form of the complex was obtained byheating solutions of the a-form in DMSO at 190°C [118].The infrared spectra of the a form (1080, 935 cm-1 [118]) may be compared tothat reported later for cis-RuBr2(DMS0)4 (1111.5, 1084, 924 cm-1) which wasstructurally characterized by the Trieste group [124]. The SO stretching frequency ofthe 0-form (1085 cm-1 [118]) corresponds well to that of trans-RuBr2(DMS0)4 (1082the structure of which was determined in 1984 [175]. It seems likely that thea and 0 forms of the complex are the cis and trans isomers of RuBr2(DMS0)4respectively, especially given that the form was isolated following the heating of thea form at 190°C in DMSO which may have induced a cis-trans isomerization of thecomplex.3.8.2 Trans-RuX2(DMS0)4, X = Cl, Br or I3.8.2(a) Trans-RuC12(DMS0)4The title complex has been synthesized in two ways; workers in this groupreacted RuC13.3H20 directly with DMSO at 70°C in air [121] to obtain the complex,while the Trieste group exposed solutions of the cis isomer in DMSO to a UV-lightsource to effect a cis to trans isomerization [124].The 1H NMR spectrum of trans-RuC12(DMS0)4 in noncoordinating solventssuch as CDC13 is considerably simpler than that of the cis isomer and consists of twosinglets at 6 3.4 ppm and 5 2.62 ppm in a 3:1 ratio, corresponding to S-bonded and free79DMSO, respectively [121,124]. The complex loses one DMSO in solution (to relievesteric strain around the equatorial axis (see Section 3.8.3(b)), and is thought to undergoa rearrangement to form a 5-coordinate trigonal-bipyramidal species with threeequivalent S-bonded DMSO ligands in the equatorial plane [124]. The 13C{1}1} NMRspectrum of the complex consists of two singlets at 42.78 and 41.14 ppm with anintensity ratio of 3 to 1, which is in keeping with three equivalent DMSO ligandscoordinated to Ru and one free DMSO [124].The stretching frequency of the SO bond, 1086 cm4 [121,124], is consistentwith S-bonded sulfoxides (Section 3.6.2). The crystal structure of this complex wasdetermined independently by the two groups [121,124], and the DMSO ligands areindeed all S-bonded; the bond lengths and angles for the two structures are in goodagreement.The synthetic route used for preparing trans-RuC12(DMS0)4 directly fromRuC13.3H20 [121] is similar to one of the routes used for preparation of the cis-isomer[108]; in both cases, a solution of RuC13.3H20 in DMSO is heated. The twoprocedures used were essentially the same except that a lower temperature (70°C) wasused in the synthesis of the trans isomer while the cis isomer was obtained when thereaction mixture was refluxed. There have been problems in this thesis work, however,with the reproducibility of the "heating" route to the trans isomer; the complex,Ru2C16(DMS0)4, was obtained instead. When solutions of this dinuclear species inDMSO are exposed to sunlight, however, trans-RuC12(DMS0)4 is isolated as a fineyellow precipitate (see Section 3.8.6). Other workers in this laboratory have isolated the80trans-complex from solutions of Ru2C14(C6H6)2 in DMSO at ambient temperatures[176]; the cis isomer was obtained instead, however, when a similar solution wasrefluxed.3.8.2(b) Trans-RuBr2(DMS0)4The trans dibromo complex was first synthesized in this laboratory [106] byrefluxing DMSO solutions of RuBr3 under H2. The crystal structure of this complexwas determined later [175], and confirmed the trans geometry. The anti-tumour activityof this complex in vivo was also studied by the Trieste group as part of theirinvestigations into cis/trans, Cl/Br - activity relationships of Ru(II)-sulfoxide complexes[124], and the findings have been summarized in Section 1.14 (p.33). The complex hasalso been isolated, as part of this work, from reaction solutions consisting ofRuC13.3H20, LiBr and DMSO in methanol [171(c)].3.8.2(c) RuI2(DMS0)4The preparation and isolation of RuI2(DMS0)4 has also been reported[118,119(a)], but spectroscopic details are sketchy; just the elemental analysis (C, H andI), and the infrared spectra of the complex in the solid state are given. The reactionprocedures followed by both groups were similar and, according to the assignments ofthe SO stretching frequencies in one report (1125, 1065 and 920 cm-1 [118]), thecomplex was said to contain both 0- and S-bonded DMSO. In the later report [119(a)],however, the infrared data (1079 cm-1) indicate that all the DMSO ligands are S-81bonded; in addition, these authors report that the infrared spectrum is identical to thatof trans-RuBr2(DMS0)4, and on this basis, imply a trans geometry for the complex.No 1H NMR data were reported and the trans assignment for RuI2(DMS0)4 is tentativeat best.3.8.3 The Crystal Structures of' RuX2(DMS0)4 Complexes, X = Cl or Br3.8.3(a) Cis-RuCl2(DMS0)4 and cis-RuBr2(DMS0)4Three crystal forms for cis-RuC12(DMS0)4 have been determined[107,124,177]; the molecular geometries of the three structures are very similar,each being distorted octahedra (see Figure 3.4). The only significant differences foundamong the three crystal forms are in the degree of rotation of the S-bonded DMSOligands about the Ru-S bond [124]. The different conformations induce variations insome corresponding bond lengths (e.g. Ru-S(3), 2.269 to 2.284 A; S(3)-0(3), 1.461 to1.481 A) and bond angles (e.g. C1(2)-Ru-S(1), 89.44 to 96.69°), which indicate that adifferent degree of intramolecular steric interaction is present within each molecularform [124]. The differences in the S-0 bond lengths are reflected in the SO stretchingfrequencies (which range from 1108 to 1122 cm-1) for the S-bonded DMSO ligands inthe three molecular forms [124].Cis-RuBr2(DMS0)4 is isostructural with cis-RuC12(DMS0)4, and the Ru-S andRu-O bond lengths of the two mutually trans DMSO ligands for the dibromo anddichloro complexes are comparable. The corresponding S-0 bond lengths within each82Figure 3.4 Diagram of cis-RuC12(DMS0)4 showing thearenumbering scheme; adapted from ref. 124complexalso similar (see Table 3.5). The average Ru-S bond lengths for the DMSO ligandstrans to the halides are longer in the dibromo than in the dichloro complex (2.295 vs.2.277 A, respectively) due to the greater trans influence of Br compared to Cl [124].As expected, the average Ru-Br bonds are longer than the Ru-C1 bond lengths (2.563vs. 2.423 A, respectively).3.8.3(b) Trans-RuC12(DMS0)4 and trans-RuBr2(DMS0)4The structures of trans-RuX2(DMS0)4 (X =C1 and Br) containing only S-bondedsulfoxide are naturally considerably simpler and more symmetric than those of the cisanalogues. Selected bond lengths for both trans complexes are tabulated in Table 3.5,83and they are generally similar with the exception of the Ru-X bond where the Ru-Brbond length (2.540(1) A [175]) is longer than the corresponding Ru-Cl bond (2.402 A[121,124]). The structure of trans-RuC12(DMS0)4 is reproduced in Figure 3.5.Table 3.5 Selected Bond Lengths for the RuX2(DMS0)4 SystemsBond RuX2(DMS0)4, X = Cl or Brcis, X =C1 cis, X =Br trans, X=C1 trans, X =BrRu-X 2.435(1) 2.562 2.42 2.540(1)Ru-S 2.277a 2.295a 2.353 2.360(1)Ru-S 2.252(1)b 2.253(2)1)Ru-O 2.142 2.143(5)S-0 1.484 1.470 1.491 1.484(3)S-0 1.557(4) 1.537Ref. 107 124 121,124 175a trans to X.b trans to 0.Of note, the Ru-halide bonds in the cis isomer are slightly longer than thecorresponding bond lengths in the trans isomer. The two halogens are considered moresterically hindered in the cis than in the trans positions which allows the two halogenatoms to remain further apart, and so the longer bond lengths may help relieve somesteric strain in the cis isomers.The Ru-S bond lengths in the trans isomers are considerably longer than thosefound in the cis isomers (e.g., 2.36 vs. 2.29 A, respectively, see Table 3.5) due to thetrans influence of the sulfurs, and crowding of the four DMSO ligands in the equatorial84Figure 3.5 A stereoview of trans-RuCl2(DMS0)4; taken from ref. 121plane [121,124]. Unlike in cis-RuC12(DMS0)4, where some measure of steric crowdingis relieved by one DMSO coordinating through 0 in the cis isomer [107], the DMSOligands in the trans isomer are all S-bonded (Table 3.5).3.8.4 The Geometry of the DMSO Ligands Within the RuX2(DMS0)4 Complexes,X = CI or BrThe bond angles for the four Ru/DMSO (cis/trans, Cl/Br) complexes aretabulated in Table 3.6, and indicate that the geometry of the coordinated DMSO ligandsin the complexes is close to that of the free sulfoxide. The C-S-C and C-S-0 bondangles within the S-bonded DMSO ligands (Table 3.6) are essentially the same as thosefound in free DMSO (Table 3.1, p.61). The same holds true for the 0-bondedsulfoxides except that the C-S-D bond angles are slightly diminished (107°-•103°, freeand 0-bonded DMSO, respectively).85Table 3.6 Selected Bond Angles for the DMSO ComplexesComplex RuX2(DMS0)4, X = Cl, BrAngle (°) cis, X=C1 cis, X=Br trans, X=C1 trans, X=BrRu-S-0 120 117 112.9(1) 112.5(1)Ru-S-C 112 114 115.1(1) 116.0(1)C--0 107 106 106.0(2) 105.7(1)C-S-C 99 101 100.5(3) 99.6(2)Ru-O-S 120.0(2) 120.7(3)C-S-0 103 103C-S-C 99.0(4) 98.9Ref. 107 124 121,124 175The average Ru-S-0 bond angles within the S-bonded DMSO ligands in the transisomers (1130) are significantly smaller than the corresponding angles in the cis isomers(119°), indicating more steric interaction is present between the four S-bonded DMSOligands in the equatorial plane of the trans isomers compared to that in the cis isomers;this is also reflected in the Ru-S bond distances found within the isomers (trans Ru-S> cis Ru-S, see Table 3.5).The lower thermodynamic stability of the trans relative to the cis isomers isprobably due to these steric factors, as in the cis species some degree of steric hindranceis relieved by one 0-bonded DMSO [124]. The behaviour of trans-RuX2(DMS0)4 insolution also corroborates these arguments, as one S-bonded DMSO is released86immediately upon dissolution of the complex even in non-coordinating solvents torelieve steric strain [124]. The Ru-O-S bond angles are in the 1200 range whichindicates that the 0 is sp2; this is compatible with the earlier discussion on the bondingmodel for 0-bonded sulfoxides (see Section 3.4, p.64).3.8.5 Ru2C14(DIVIS0)5Several attempts to synthesize ruthenium-sulfoxide complexes were made usingcis-RuC12(DMS0)4 as the source of ruthenium in sulfoxide exchange reactions withother sulfoxides (Et2S0, nPr2S0, nBu2S0 and Ph2S0). Solutions of cis-RuC12(DMS0)4 in methanol were refluxed with each of the above sulfoxides; noproducts were isolated following the reflux procedures using either Et2S0 and Ph2S0,but a fine yellow precipitate was obtained with nPr2S0 and nBu2S0, which analyzedfor the title dinuclear complex containing only the DMSO ligand. When cis-RuC12(DMS0)4 is refluxed in Me0H in the absence of other sulfoxides, the dinuclearspecies does not form, and the starting material is recovered. The Trieste group reportsthat complete exchange is seen with TMSO under similar conditions, and that cis-RuC12(TMS0)4 is isolated; similarly, trans-RuC12(TMS0)4 was obtained when trans-RuC12(DMS0)4 was used in place of the cis DMSO precursor [172(c)].The dinuclear complex, Ru2C14(DMS0)5, was first reported in the literature in1979 [114], and was isolated following an attempted reaction of 8-(diphenylphosphino)quinoline with cis-RuC12(DMS0)4, and also from refluxing cis-RuC12(DMS0)4 in toluene. The formulation of the dimer was based on elemental87analysis for C, H, Cl and S, while the presence of S-, 0-bonded and bridging DMSOwas suggested on the basis of the SO infrared stretching frequencies (1110 and 1090,928 and 910, 965 cm-1 assigned to S-bonded, 0-bonded and bridging DMSO,respectively) [114].More detailed studies [115] were carried out later on this complex which wasmade by refluxing cis-RuC12(DMS0)4 in toluene; the deuterated analogue, Ru2C14(d6-DMS0)5 was also synthesized. Comparison of the infrared spectra for both complexesindicated that the DMSO ligands were all S-bonded (v50: 1135, 1115 and 1095 cm-1),and that the bands in the lower range (1020, 970, 930 and 914 cm-1) were due to CH3rocking modes [115]. High resolution NMR studies indicated that the structure had threeinequivalent sets of S-bonded sulfoxides of integration 2:2:1. On the basis of the IR andNMR spectral data, the structure was reformulated as a triply chloro-bridged dinuclearcomplex with all S-bonded, terminal sulfoxides and one terminal chloride [115].The Trieste group has recently informed us that the structure of the complex hasnow been determined [116], and the structure does indeed confirm that proposed byHeath et al. [115]. The complex was synthesized by stirring a methanolic solution ofcis-RuC12(DMS0)4 at room temperature for 8 hours, and crystals formed within a weekof adding diethylether to the solution [116]. The dinuclear species consists of tworuthenium atoms which each have a distorted octahedral geometry sharing the trichloroface. Three DMSO ligands are S-bonded to Ru(1) in a facial configuration, while Ru(2)has one Cl and two cis DMSO ligands. The Ru-Ru distance (3.2363(4) A) is reportedlythe shortest known for Ru(II)-(A-C1)3-Ru(II) complexes which generally fall in the88range 3.35 - 3.44 A; the Ru-Ru distance is, however, comparable to the correspondingdistance found within low-spin Ru(II)-(A-C1)3-Ru(III) phosphine complexes (3.115 -3.28 A) [116]. The authors report also that the Ru(1)-S bond lengths are significantlylonger than those of Ru(2)-S, which may be due in part to a greater amount of back-bonding to the DMSO ligands, and a decrease in intramolecular steric interactions onRu(2).The presence of water in the reaction solvent is probably critical for formationof the dinuclear DMSO complex. When the refluxing procedure was carried out inrigorously dry toluene, only the starting material was recovered [115]. Water presentin the reaction mixture is thought to replace the labile 0-bonded sulfoxide of cis-RuC12(DMS0)4 initially, and then to be lost in refluxing toluene which leads tocondensation of the monomeric species to form the dinuclear species; similar results areobtained using dry and wet ethanol [115]. The complex was reported to be moderatelysoluble in CHC13 [114] and CH2C12 [115] but not in other common organic solvents.The compound isolated in this present work is insoluble in CH2C12 and CHC13,in contrast to the two earlier reports but dissolves readily in DMSO and water. The 1HNMR spectrum of the complex in d6-DMS0 is uninformative, and consists of one peakcorresponding to free DMSO due to exchange of deuterated solvent with all thecoordinated DMSO. In D20, the observed 1H NMR spectrum is similar to that of cis-RuC12(DMS0)4 in D20 [108] which tends to support the earlier report [115] that thedinuclear species rearranges in water to yield the original starting material, cis-RuC12(DMS0)3(DMS0), and its dissolution products cis-RuC12(DMS0)3(H20) and89free DMSO (Section 3.8.1(a)). On the basis of the structure, the expected products fromthe dinuclear complex breaking up in water would be cis,fac-RuC12(DMS0)3(H20) andcis,cis,cis-RuC12(DMS0)2(H20)2 [116]. The Trieste group report, however, thatRu2C14(DMS0)5 decomposes in water to yield cis, fac-RuC12(DMS0)3(H20) andtrans,cis,cis-RuC12(DMS0)2(H20)2 in equimolar amounts; the reported protonresonances for these species [116] are in the same range as those for the S-bondedDMSO ligands in cis-RuC12(DMS0)4 [108].The infrared spectrum of the complex isolated in the present work has IR bandsat 1111 and 1087 cm-1 due to S-bonded DMSO, and bands at 1022, 974 and 925 cm-1which, following the IR data reported previously [115], are attributed to CH3 rockingmodes. The complex obtained in these attempted exchange reactions is likely the sameas that isolated previously [114,115] despite the differences in solubility. Unfortunately,the lack of solubility in various solvents has prevented attempts to determine themolecular weight using the Signer method [139]. No parent peaks were found usingMass Spectroscopy (El or FAB).It is interesting to note that in the exchange reaction with TMSO, thecorresponding cis-RuC12(TMS0)4 complex, and not Ru2C14(DMS0)5, is formed. TheDMSO ligands in cis-RuC12(DMS0)4 undergo complete exchange with deuteratedDMSO [108] and, on this basis, the Trieste group adopted the exchange reaction as ageneral synthetic route to the TMSO complexes [172(c)] (Section 3.8.1(a)). It is possiblethat the TMSO ligand, having a smaller cone angle [121,172(c)] than DMSO and otherhigher sulfoxides, is able to remain within the coordination sphere of the Ru, compete90more effectively with impurity water, and prevent formation of the dimer, thus allowingfor complete exchange of the DMSO ligands with TMSO.3.8.6 Ru2C16(DMS0)4The compound, Ru2C16(DMS0)4, together with the fac- and mer- forms ofRuC13(DMS0)3 was first reported in the literature in 1988 [119(b)], and in an attemptto gain access to Ru(III) complexes, the synthetic procedures for all three complexeswere later repeated by workers in this laboratory; however, trans-RuC12(DMS0)4,RuCI3(DMS)3 (where DMS = dimethylsulfide) and [H(DMS0)2][trans-RuC14DMS0)2], respectively, were isolated instead. The structures of all threecomplexes were confirmed by X-ray crystallography [121] (see Section 3.10.1).However, in subsequent attempts in the present thesis work to synthesize trans-RuC12(DMS0)4 from the reported procedure [121], the title complex was obtained. Thesimple procedure (RuC13.3H20 was heated in DMSO at 70°C in air for 15 min, andthe complex precipitated with acetone) was followed as closely as possible, but theisolated red precipitate analyzed well (C, H and Cl) for the dimer and not trans-RuC12(DMS0)4! The magnetic moment of the complex in the solid state was, however,close to zero indicating that the complex is diamagnetic despite the apparent presenceof the two Ru(III) centres. The measured diamagnetism of the complex is surprising butis corroborated by the 1H NMR spectra which have sharp peaks.The complex has limited solubility in most common solvents but dissolvesreadily in DMSO and acetonitrile. The 1H NMR spectrum of the complex was91measured in CD3CN and CDC13. Two sharp singlets, attributable to the methyl groupsof DMSO, and which correspond to free and S-bonded DMSO, were observed inCD3CN; in CDC13, only a single peak due to free DMSO was observed. No 1H NMRdata were reported by Poddar's group but a magnetic moment (IJeff = 1.1 BM) wasobtained using a Faraday balance [119(b)]. In addition, the authors reported observingg values of 2.37, 2.14 and 1.88 in the ESR spectrum of the dinuclear complex.The UV-Vis data for the complex in DMSO and acetonitrile are similar(Xmaxnm (log c): 463 (3.87), 356.3 (3.68) and 462.4 (3.65), 357 (3.47), respectively),although the extinction coefficients are lower in acetonitrile. The UV-Vis spectrum ofthe complex in CH2C12 was also measured, and the absorption maxima (465 and 358nm) were very similar to those in DMSO and acetonitrile, although the extinctioncoefficients were not measured. The UV-Vis spectral data do not correspond well withthose reported by Poddar's group [119(b)] (455 nm (4.07) and 457 (4.02) in acetonitrileand CHC13, respectively).The infrared spectrum of the complex isolated in this present work has strongbands at 1032, 985 and 891 cm-1 which are lower than vso for free DMSO which isobserved at 1055 cm-1. The data suggest the presence of 0-bonded DMSO, and the lackof any strong bands above 1055 cm-1 indicates the absence of S-bonded DMSO.Poddar's group reports bands for this complex at 1110 cm-1 (assigned to S-bondedDMSO) and bands at 1028, 1019 cm-1 (assigned to C-H rocking modes) and 891 cm-1(0-bonded DMS0); the assignments reported by Poddar's group were made bycomparison with the deuterated analogue of the suggested dimer [119(b)].92The spectroscopic data obtained for this compound do not allow the assignmentof a definite structure, although the formulation of the complex (based on analysis forC, H and Cl) is probably correct. The discrepancies with the data reported previously[119(b)] cannot be explained at the present time. The diamagnetism of the complex mayperhaps be explained by the presence of a Ru-Ru metal bond which has been proposedfor some Ru(III)-(y-C1)3-Ru(III) phosphine complexes [178]. The complex in thesolid state appears to have 0-bonded DMSO but in CD3CN appears to have S-bondedDMSO. No satisfactory explanation is available for this apparent contradiction, althoughconceivably any dimer present may break up in CD3CN and undergo somerearrangement. In addition, there is no obvious explanation why trans-RuC12(DMS0)4is isolated sometimes, and Ru2C16(DMS0)4 at other times when identical reactionprocedures are followed. Also of interest, Poddar's group was originally trying tosynthesize RuC13(DMS0)3, following an earlier report in the literature [179], butisolated Ru2C16(DMS0)4 instead!Of some interest, when solutions of the dimer in DMSO are refluxed, a yellowprecipitate is obtained which analyzes for cis-RuC12(DMS0)4. When similar solutionsare exposed to sunlight for a few days, the colour of the solution lightens (deep red toyellow), and orange crystals which analyze for trans-RuC12(DMS0)4 are depositedinstead. The isolation of the Ru(II) complexes indicate that reduction of the Ru(III)centres occurs with perhaps the concomitant oxidation of DMSO to the correspondingsulfone. Such reactions are known to occur [188], and the Trieste group has detectedthe presence of stoichiometric amounts of dimethylsulfone in the reduction of93RuC13(DMS0)3 to RuC12(DMS0)4 [157], Section TMSO Complexes of RunThe chemistry of ruthenium-TMSO complexes is just as varied and intricate asthat of the DMSO complexes. There were a few reports in the 1970s on ruthenium-TMSO complexes [117,118] but in recent years more details have been reported[50,171,172(c)], some of which originated from this present work. As with the DMSOcomplexes, structural data have been invaluable in assigning the geometry of the TMSOcomplexes and in laying down a framework for outlining the chemistry of thesecomplexes. Relevant data from the literature are presented in conjunction with thepresent work to provide a more complete account of this particular field of Ru-sulfoxidechemistry.3.9.1 Cis-RuX2(TMS0)4, X = CI or BrThe synthetic and spectroscopic details of the dichloro and dibromo complexesare discussed in Sections 3.9.1(a) and 3.9.1(b). The structure of cis-RuC12(TMS0)4 wasdetermined during the course of this present work, and the details are discussed inSection 3.9.2; no structural data for the dibromo complex have been reported.3.9.1(a) The Synthetic and Spectroscopic details for cis-RuC12(TMS0)4The synthesis of RuC12(TMS0)4 was first reported in the late 1970s [117,118]although no geometry was assigned to the complex. The compound was also used by94workers in this group as a precursor to Ru(II)-TMSO-nitroimidazole complexes whichwere evaluated as metal based radiosensitizers [50]. Subsequent to this work, thestructure of the cis-complex was determined as part of the present work [171(a)] andalso by the Trieste group [172(c)], simultaneously and independently.There are now three procedures reported for the synthesis of cis-RuC12(TMS0)4. In studies by this group, TMSO was added to the "ruthenium-blue"solutions (see Section 2.4.1, p.45), and the mixture refluxed to give the compound ingood yield [50,171(a)]; the Trieste group synthesized the complex by a sulfoxideexchange reaction between TMSO and cis-RuC12(DMS0)4 [172(c)] (see also Section3.8.5), while Bora and Singh made the complex by adding TMSO to a solution ofRuC13.3H20 in refluxing ethanol [117,118].The Trieste group obtained one crystal form of cis-RuC12(TMS0)4 from asolution of the complex in TMSO [172(c)], while two crystal forms (one of which isisostructural with that of the Trieste group) were obtained during this present work froman attempted reaction of cis-RuC12(TMS0)4 with etanidazole, a 5-nitroimidazole; thestructural details of the complex are presented in Section 3.9.2 and were published inref. 171(a).The first report on this complex [118] contained limited spectral data, and theformulation of the complex was based on elemental analysis. The infrared data showedthat the SO stretching frequency of free TMSO increased upon coordination (1020 to1125 and 1065 cm-1 [118]) indicating that the TMSO ligands were S-bonded. Thesedata agree well with those obtained in this present work (1121, 1064 cm-1 [171(a)]) and95by the Trieste group (1122 cm-1 [172(c)]) for cis-RuC12(TMS.0)4 which wasstructurally characterized.In a previous publication [50], the SO stretching frequencies for the coordinatedTMSO were reported at 1133 and 1094 cm-1, while that of the free ligand wasincorrectly said to be at 950 cm-1. The IR data in this report [50] do not agree with thelater work [118,171(a), 172(c)]. The other spectral data (UV-Vis and proton NMR [50]),however, are in good agreement with the later studies [171(a),172(c)]. The complex wasalso originally assigned a trans geometry [50], on the basis of the deceptively simple1H NMR spectrum observed for the compound; the geometry was subsequently shownto be incorrect [171(a),172(c)]. Indeed, the 1H NMR spectra of both free andcoordinated TMSO are more complicated than previously thought; the 1H NMRspectrum (300 MHz) of the free ligand in CDC13 consists of three multiplets centred at(5 1.63, 2.00 and 2.58 ppm with integration ratios of 1:1:2, respectively. Of someinterest, two other groups observe only two multiplets of equal intensity centred at 52.22 and 2.89 ppm (assigned to the 13 and a-protons of the ligand, respectively)presumably due to the use of 80 [172(c)] or 60 MHz [180] NMR instruments. TheTrieste group has, however, recently observed the same spectrum as ours [171(a)] withthe use of a 300 MHz NMR instrument [190].The multiplets at (5 1.63 and 2.00 ppm were initially assigned to the inequivalenta-protons (Ha and Hb) despite the relatively lower chemical shift of the two peaks, andthe remaining multiplet at ô 2.58 ppm to the 0-protons of TMSO [50,171(a)] becausethe inequivalence of the a-protons was expected to be greater than that of the 0-protons.9655 -50 -45 -40 -35 -3025 -111111I IIII/IiIIIIIIIIIIIII11/[11111111/11IIIIIIIIIITTTIIIIIIIIIIITT2.8^2.6^2.4^2.2^P.0^1.8^1.6^1.4^1 dFigure 3.6 HETCOR 2D array for TMSO in CD2C12A HETCOR experiment on a solution of free TMSO in CD2C12 (Figure 3.6), however,indicates that the converse is true, and the original assignments have since been revisedin ref. 171(c). The multiplets at 6 1.63 and 2.00 ppm in the 1H NMR spectrum bothcorrelate with the resonance at 6 25 ppm in the 13C{ 1 H} spectrum while the protonmultiplet at 6 2.58 ppm correlates with the remaining 13C resonance at (3 55 ppm. Thepeaks at 6 25 and 55 ppm in the 13C{1H} spectrum are assigned to the 0- and «-carbons, respectively, based on predicted shielding effects [171(c)]; the positions andassignments of the peaks for free TMSO in the 13C{1H} spectra agree with thosereported by the Trieste group (6 24.36 and 54.42 ppm for the (3 and a-carbons,respectively) [172(c)]. The data from the HETCOR experiment thus show that theresonance at 6 2.58 in the 1H NMR is due to the a-protons while those at .3 1.63 and2.00 ppm are due to the 0-protons, although why the 0-protons are more inequivalentthan the «-protons in free TMSO is not immediately obvious. The a-protons in the non-cyclic sulfoxides studied in the present work are, without exception, all moreinequivalent than the remaining protons (Chapter 2). Presumably, there is some stericeffect caused by ring constraints in TMSO that makes the 0-protons more inequivalent.The original peak assignments for free TMSO and cis-RuC12(TMS0)4 reportedpreviously [50,171(a)] have thus been revised [171(c)]. The 1H NMR spectrum of cis-RuC12(TMS0)4 in CDC13 consists of three multiplets which are now assigned asfollows: the two multiplets at 6 3.44 and 4.13 ppm are due to the a-protons which areshifted downfield from the multiplet at 2.58 ppm in the 1H NMR spectrum of freeTMSO [171(c)] (rather than from 6 1.63 and 2.00 ppm as originally thought [171(a)]).98The remaining multiplet centred at 6 2.26 ppm is due to the 0-protons which havemoved downfield from 6 1.63 and 2.00 ppm upon coordination of the TMSO [171(c)](rather than somewhat upfield from 6 2.58 ppm as originally assigned [171(a)]).Decoupling experiments also corroborate the assignments of the peaks in the protonNMR spectrum of cis-RuC12(TMS0)4; thus decoupling the 0-protons at 6 2.26 ppmresults in the simplification of the multiplets at 6 4.13 and 3.44 ppm into doublets asexpected for the diastereomeric a-protons.Two sets of TMSO ligands are present (one set trans to Cl and the other setmutually trans) in cis-RuC12(TM50)4, and the Trieste group [172(c)] has assigned theproton resonances at c 3.44 and 4.13 ppm of the complex to the a-protons within thetwo sets of TMSO implying that the inequivalence of the a-protons is not well resolvedwithin each multiplet. The differences in the chemical shifts of the two sets of ligandsare, however, unlikely to be resolved because the width of the multiplets areconsiderably larger than for example, the methyl resonances of the different DMSOligands in cis-RuC12(DMS0)3(DMS0) [107,108].In fact, a HETCOR experiment on a saturated solution of the complex inCD2C12 (Figure 3.7) confirms that the multiplets at 6 3.44 and 4.13 ppm are due to theinequivalence of the a-protons (Ha and Hb) within the TMSO ligands and not the twosets of TMSO ligands within the complex. The 13C{1H} NMR spectrum of cis-RuC12(TMS0)4 has three peaks; the 0-carbons are essentially unaffected bycoordination and the resonance remains at 6 25 ppm while the a-carbons are now splitinto two resonances at 6 57 and 60 ppm corresponding to the two sets of TMSO ligands.998Figure 3.7 HETCOR 2D array for RuC12(TMS0)4 in CD2C1265 -4==:1,^4:C==D60 -0:=0^<C==1,55 -50 -45 -40^-35 -30 -C:11111DO",i,2520 -r^TT' I1^I^IIIJl I^^Tilt^I^111^I^I^Ij4.5^4.0 3.5 3.0^2. 5 2 . 0The two dimensional array generated from the HETCOR data (Figure 3.7) shows thatthe multiplets at .5 3.44 and 4.13 ppm in the 1H NMR spectrum each correlate with boththe 13C resonances at 6 57 and 60 ppm. In contrast, a one to one correlation betweenthe a-protons with the a-carbons would have been observed had the multiplets been dueto the different sets of TMSO ligands within the complex. The peak at 6 25 ppm in the13C{1H} spectrum due to the 13-carbons, as expected, has a one to one correlation withthe proton resonance centred at 6 2.62 ppm due to the 13-protons within the TMSOligands.The inequivalence of the a-protons within free TMSO increases uponcoordination (6 2.58 ppm to (5 4.13 and 3.44 ppm) which is consistent with coordinationthrough S [168,142]. The a-carbons are more deshielded than the )3-carbons due to theproximity of the former to the SO moiety (Sections 3.4 and 3.6.1, pages 64 and 68,respectively) as expected. The carbon resonance at 6 55 ppm (a-carbons of free TMSO[171(a), 172(c)]) is shifted downfield to 6 57 or 60 ppm due to coordination of thesulfoxide; the split is due to the presence of two sets of TMSO ligands, cis to S and Cl,respectively.3.9.1(b) The Synthetic and Spectroscopic details for cis -RuBr2(TMS0)4Cis-RuBr2(DMS0)4 was used in a sulfoxide exchange reaction with TMSO, ina manner analogous to the synthesis of the chloro analogue (Section 3.9.1(a)), as asynthetic route to cis-RuBr2(TMS0)4 [172(c)]. The TMSO ligands in the cis-bromocomplex are all S-bonded (like in the chloro analogue), and the geometry of the101complex was tentatively assigned [172(c)] by analogy of the UV-Vis spectra of thecomplex to those of cis- and trans-RuC12(DMS0)4; the cis complexes absorb at a lowerwavelength (360-370 nm) than the trans complexes (440-460 nm) [172(c)]. In addition,cis and trans-RuBr2(TMS0)4 are related by a cis to trans photochemical isomerizationwhich is analogous to that found with the chloro/TMSO and chloro/DMSO systems[172(c)] (see Section 3.9.3(a)). The complex was also isolated in this present work froma reaction solution consisting of RuC13.3H20, LiBr, and TMSO in Me0H (see Section3.9.5)The 1H NMR spectrum of cis-RuBr2(TMS0)4, measured in the present workand not reported by the Trieste group, is complicated, although generally similar to thatof the cis-dichloro complex, and consists of overlapping multiplets in each of the rangesS 2.00 - 2.60, 2.8 - 3.00 and 3.20 - 4.70 ppm [171(c)]. Two of the multiplets centredat (5 2.10 and 2.55 ppm are possibly due to free TMSO while the multiplet centred at2.30 could be due to the fl-protons of coordinated TMSO. The remaining multiplets aredue to the a-protons of coordinated TMSO. Due to the complexity of the spectrum,however, no definite assignments can be made [171(c)].3.9.2 The Crystal Structures of cis-RuCl2(TMS0)4, form a and form bTwo crystal forms of the title compound were obtained from the workup of anunsuccessful reaction involving cis-RuC12(TMS0)4 and etanidazole. The crystals canalso be obtained from methanolic solutions of the complex; the Trieste group obtainedtheir crystal from solutions of the complex in warm TMSO [172(c)]. The two crystal102types obtained in the present work (forms a and b) are monoclinic although they havedifferent space groups, C2/c (form a), and P21/c (form t). The structure reported bythe Trieste group [172(c)] is that of form h, and both data sets are in good agreement.Selected bond lengths and angles for both crystal forms are found in Tables 3.7 and 3.8.The structure of the complex (form a) is reproduced in Figure 3.8, a stereoview of theTable 3.7 Selected Bond Lengths and Angles for cis-RuC12(TMS0)4, form a;published in ref. 171(a)Bond Lengths (A) Bond Angles (0)atom atom distance atom atom atom angleRu(1) C1(1) 2.425(1) 5(1) Ru(1) C1(1) 177.42(5)Ru(1) S(1) 2.274(1) S(2) Ru(1) S(2) 172.32(5)Ru(1) S(3) 2.341(1) 5(1) Ru(1) 5(1) 94.50(5)S(1) 0(1) 1.475(3) S(2) Ru(1) C1(1) 85.45(3)S(2) 0(2) 1.477(3)complex with 50% probability thermal ellipsoids is shown for the non hydrogen atoms.The structures for both crystal forms show close to octahedral geometry at theRu with trans bond angles ranging from 1720 to 1770, and cis bond angles from 850to 94° ([171(a),172(c)], Tables 3.7 and 3.8). The average Ru-Cl bond lengths in bothcrystal forms are essentially the same (2.43 A [171(a)]) and correspond well with thosewithin cis- and trans-RuC12(DMS0)4 (2.435 [[107] and 2.432 A [121,124],respectively). The Ru-S bond lengths trans to S within both forms a and b (2.341 and2.357 A, respectively) are longer than those trans to Cl (2.274 and 2.275 A) [171(a)]),103Figure 3.8 A stereoview of cis-RuC12(TMS0)4, form a; taken from ref. 171(a)and the difference in length can be attributed to the stronger trans influence of S[171(a), 181]. This is analogous to the effects found in related DMSO systems,although the corresponding Ru-S bond lengths in the DMSO systems are marginallyshorter (2.277 and 2.252 A [107,109,124,175]).The average S-0 bond lengths in a and b (1.476 and 1.479 A, respectively[171(a)]) are shorter than that found in crystalline TMSO (1.527 A [153]) as expectedfor S-bonded sulfoxides (see Section 3.4, p.64), and a corresponding increase in uso forfree TMSO is observed (1022 to 1121 and 1064 cm-I) upon coordination to Ru.Of some interest, while cis-RuC12(TM50)4 has exclusively S-bonded ligands,the DMSO analogue has one 0-bonded DMSO thought to be due to crowding at the Ru104Table 3.8 Selected Bond Lengths and Angles for cis-RuC12(TMS0)4, form a;Published in ref. 171(a)Bond Lengths (A) Bond Angles (°)atom atom distance atom atom atom angleRu Cl 2.431 C1(1) Ru(1) S(1) 177.02(4)Ru(1) S(1) 2.276(1) S(3) Ru(1) S(4) 173.36(4)Ru(1) S(2) 2.274(1) S(1) Ru(1) S(2) 94.83(4)Ru(1) S(3) 2.352(1) C1(2) Ru(1) S(3) 84.58(4)Ru(1) S(4) 2.362(1)S^0^1.479centre [107,108]. The configuration of the ligands in the cis-DMSO and TMSOcomplexes thus implies that TMSO is sterically less demanding than DMS0 which isevident from the average C-S-C bond angles within DMS0 (98.3° [107,124]) andTMSO (92.8° [171(a),172(c)]) in the respective complexes. The significantly smallercone angles in TMSO means that the four ligands are accommodated more easily at theRu centre despite being S-bonded. In contrast, one DMSO in cis-RuC12(DMS0)4 bindsthrough 0 to relieve steric anxiety due to the relatively larger cone angles of DMSO.3.9.3 Trans-RuX2(TMS0)4, X = Cl or Br3.9.3(a) Trans-RuC12(TMS0)4The Trieste group has reported two synthetic pathways to trans-RuC12(TMS0)4105[172(c)]: the first by a DMSO/TMSO exchange with trans-RuC12(DMS0)4 and thesecond by a photochemically induced cis to trans isomerization of cis-RuC12(TMS0)4in TMSO. The geometry of the complex was assigned by analogy of the UV-Visspectrum to that of trans-RuC12(DMS0)4 (see Section 3.9.1(b)) as no structural datawere available. The vsb infrared data (1129, 1109 cm-1) reported for trans-RuC12(TMS0)4 [172(c)] indicate that, like the cis isomer, the ligands are all S-bonded.The reported 1H NMR spectrum of trans-RuC12(TMS0)4 in CDC13 [172(c)]consists of four multiplets centred at 6 2.26, 2.88, 3.38 and 3.88 ppm with intensityratios of 8:2:3:3, respectively. The observed pattern in the proton spectrum is explainedin part by the dissociation of one TMSO which accounts for the multiplet at 5 2.88 (a-protons of free TMSO [172(c),180]. The multiplets centred at 6 3.38 and 3.88 ppm areconsidered to be due to the a-protons (Ha and Hb) of the three S-bonded TMSOligands, while the multiplet at 6 2.26 ppm is due to the 0-protons of TMSO (free andcoordinated) [172(c)]. The 13C{1H} NMR spectrum of the complex consists of two setsof two signals for free TMSO (6 24.36 and 54.52 ppm) and coordinated TMSO (6 25.19and 56.89) with an overall intensity ratio of 1:3 [172(c)], and the species in solution isthought to be a trigonal bipyramid with three equivalent TMSO molecules in theequatorial plane [172(c)]. The complex in solution loses one TMSO ligand to relieve thesteric strain imposed by the presence of four S-bonded TMSO ligands which accountsfor the destabilization of the complex with respect to the cis isomer [172(c)]; thisbehaviour parallels that found with trans-RuC12(DMS0)4 [121,124].1063.9.3(b) Trans-RuBr2(TMS0)4The syntheses of cis- and trans-RuBr2(TMS0)4 have been reported [118,172(c)],and the geometry of the cis and trans isomers assigned, in the absence of structuraldata, by analogy of their respective UV-Vis spectra to those of cis- and trans-RuBr2(DMS0)4 [172(c)]. The isolation of cis- and trans-RuBr2(TMS0)4 in this presentwork resulted from the worlcup of a reaction in which a solution of RuC13.3H20,excess LiBr and TMSO had been refluxed in an attempt to access Ru/Br/TMSO systemsdirectly. However, the major product of the reaction, while still a Ru(II)/Br/TMS0complex, is much more interesting than expected and consists of a dimeric moleculewhich is best represented as [Br6(TMS0)2Ru2(p2-TMS0)2(//3-TMS0)2Li2(TMSD)2].The details pertaining to this dimeric complex have been published [171(b) & (c)] andare discussed in Sections 3.9.5 and 3.9.6.The CC14 washings from the isolation of the dimer were retained, and a yellowsolid which analyzed well for RuBr2(TMS0)4 precipitated from the solution (Section3.9.1(b)). The spectroscopic data for this precipitate (UV-Vis; Xmax: 369 nm and IRv50: 1125, 1109 cm-1 [171(c)]) compare well with the data obtained by the Triestegroup for cis-RuBr2(TMS0)4 (UV-Vis; Xmax: 374 nm and IR uso: 1125, 1107 cm-1[172(c)]). On this basis, the complex was assigned a cis geometry.An attempt to grow X-ray quality crystals from the yellow precipitate was madeusing Et0H/acetone (2:1 v/v), and some deposited orange crystals were collected,washed with small amounts of CH2C12 and acetone, and dried in air at room107temperature. The resulting structure, however, showed the recrystallized complex to betrans-RuBr2(TMS0)4 and not the cis isomer. In addition, the UV-Vis and infraredspectra of the orange crystals (UV-Vis; Xmax: 445 nm and IR vsb: 1107, 1055 cm-1)now corresponded better to the data previously reported for the trans isomer (UV-Vis;Xmax: 461 nm and IR uso: 1104, 1080 cm-1 [172(c)]). It appears that the cis isomerunderwent an isomerization to form the trans during the recrystallization step. Such cis-trans isomerizations have been studied by the Trieste group [172(c)]: solutions of trans-RuC12(TMS0)4 in TMSO at 55°C were reported to isomerize slowly with first-orderkinetics to the cis isomer [172(c)], while the reverse isomerization was seen whensolutions of cis-RuC12(TMS0)4 were irradiated with UV light [172(c)]. Such anisomerization must have occurred in the recrystallization step described above, and wasperhaps prompted by exposure to sunlight to finally yield crystals of trans-RuBr2(TMS0)4.The SO stretching frequency of free TMSO shifts to higher frequencies uponcoordination in trans-RuBr2(TMS0)4 (1107 and 1055 cm-1) which is consistent withS-bonded sulfoxides. No bands are seen in the 1000-1020 cm-1 range consistent withthe absence of 0-bonded TMSO and/or free TMSO. The 1H NMR spectrum of trans-RuBr2(TMS0)4, which has not been reported previously, consists of three multipletscentred at 2.25, 3.10 and 4.00 ppm with intensity ratios of 2:1:1, respectively. Whilethe spectrum cannot be understood in detail, the multiplets at .5 3.10 and 4.00 ppm areprobably due to the diastereomeric (Ha and Hb) a-protons on the basis of decouplingexperiments; decoupling of the 0-protons at (5 2.25 ppm reduces the other two multiplets108to approximate doublets, and decoupling one of the multiplets due to the a-protonsresults in the simplification of the other multiplets. The magnitude of the shifts,compared with the resonances observed for the free ligand (S 1.63, 2.00 (0-protons) and2.58 ppm (a-protons) [171(a)], Section 3.9.1(a)), are also consistent with S-bondedsulfoxides. No free TMSO is detected in the proton NMR spectrum of trans-RuBr2(TMS0)4 indicating that complex remains intact in solution, unlike the chloroanalogue (see Section 3.9.3(a)).3.9.4 The Crystal Structure of trans -RuBr2(TMS0)4Selected bond lengths and angles for the structure of trans-RuBr2(TMS0)4 aretabulated in Table 3.9. A stereoview, showing 50% probability thermal ellipsoids, ofthe complex is shown in Figure 3.9.The crystal structure belongs to the tetragonal system, in the I4/m space group,coincidental with that of the structure of trans-RuBr2(DMS0)4 [175]. The geometry atthe Ru centre is a perfect octahedron, and the structure is extremely symmetrical withan axial Br-Ru-Br bond angle of 180° and equatorial S-Ru-S bond angles of 90°. Aswith the other RuX2(TMS0)4 complexes [171(a),172(c)] and trans-RuX2(DMS0)4[121,124,175], all the TMSO ligands are S-bonded which, as expected, results in adecrease in the SO bond length (1.466(3) A) upon coordination of the sulfoxide to themetal. Some disordering, however, exists within the TMSO ligands at the 0-carbons.The Ru-S bonds in trans-RuBr2(TMS0)4 (2.3345 (9) A) are comparable inlength to the corresponding bonds (mutually trans sulfoxides) in cis-RuC12(TMS0)4109Figure 3.9 A stereoview of trans-RuBr2(TMS0)4 showing 50% probability thermalellipsoids for the non-hydrogen atoms(2.35 A [171(a),172(c)]) but are longer than those trans to Cl (average length: 2.275A) due to the stronger trans influence of S [104(b),171(a)]. The Ru-Br and Ru-S bondlengths in trans-RuBr2(TMa0)4 (2.5228(7) and 2.3345(9) A, respectively) are shorterthan the corresponding bonds in trans-RuBr2(DMS0)4 (2.540(1) and 2.360(1) A,respectively [175]). The trans influence exerted on the sulfoxides within each complexshould be equivalent as the respective ligands are all mutually trans. The lengtheningof the Ru-Br and Ru-S bonds with the change from TMSO to DMSO is possibly theresult of increased steric crowding at the equatorial plane. The relative steric bulk andC-S-C bond angles for the two sulfoxides were discussed in Section 3.9.2, and the coneangle of DMSO is larger than that for TMSO [171(a),172(c)]. The longer Ru-Br andRu-S bonds observed in trans-RuBr2(DMS0)4 [175] may thus compensate for the110Table 3.9 Selected Bond Lengths and Angles for trans-RuBr2(sulfoxide)4, sulfoxide= DMSO or TMSOBond type (A) Complextrans-RuBr2(TMa0)4 trans-RuBr2(DMa0)4Ru-Br 2.5228(7) 2.540(1)Ru-S 2.3345(9) 2.360(1)S-0 1.466(3) 1.484(3)Br(1)-Ru-Br(1)' 180.00Br(1)-Ru-S(1) 90.0°Ref. twa 175a tw = this work.increased steric demands imposed by DMSO.3.9.5 [RuBr3(TMS0)4Li]2This dimeric complex was isolated following attempts to synthesize Ru/Br/TMSOcomplexes directly using methanolic solutions of RuC13.3H20, excess LiBr and TMSO[171(b) & (c)] in place of Ru-Br precursors such as cis- and trans-RuBr2(DMS0)4[172(c)]. The reaction was first performed by Dr. J. Jaswal, a former member of thisgroup, and the resulting compound was indeed a Ru-bromo derivative of TMSO but wasmuch more interesting than anticipated.Prior to the structure being solved, the complex was initially formulated asRuBr2(TMS0)3 on the basis of elemental analysis for C and H. This formulation was111also prompted by claims [119(c),120] (shown later to be erroneous [171(c),172(a)],Section 3.10.1) that RuBr2(DMS0)3 had been isolated following an analogous syntheticroute, where Et0H and DMSO were used in place of Me0H and TMSO. The structure,however, showed the compound to be [RuBr3(TMS0)4Li]2; remarkably, the calculatedvalues for C and H in elemental analysis for both the dimeric complex and the 5-coordinate complex, RuBr2(TMS0)3, are essentially identical!The dimeric complex was isolated in good yield by concentration (to 5 mL) andsubsequent cooling at 0°C of the reaction mixture which prompted the precipitation ofa yellow crystalline material. This was washed with CC14 and crystals suitable for X-rayanalysis were grown from a Et0H/acetone (2:1 v/v) solution.The CC14 washings from the filtration step were retained, and a second yellowprecipitate was deposited which analyzed well for RuBr2(TM50)4 (see Section3.9.3(b)). The geometry of the complex was assigned cis by analogy of thespectroscopic data to those reported by the Trieste group [172(c)] for cis-RuBr2(TMS0)4. Recrystallization of cis-RuBr2(TMS0)4, however, resulted in theformation of crystals of the trans isomer, as shown by X-ray crystallography (seeSection 3.9.4).The "Jaswal" reaction to give the dimer is reproducible, although lower yieldsof the complex are obtained in the present work. Elemental analysis of the solidprecipitate obtained by concentration and cooling of the reaction mixture is high in C(by 1.0%) for the "RuBr3(TMS0)2Li" formulation. Addition of one equivalent ofTMSO to the formulation, however, brings the calculated values into the correct range112for the analytically determined values. Free TMSO was not detected using proton NMR(see below) but exchange processes could be occurring as the spectrum is complex. Thecomplex was heated at 100°C in vacuo in an attempt to remove residual solvent orTMSO but the complex decomposed. In the present work, the CC14 and acetonewashings of the yellow precipitate did not precipitate any complex but the mother liquornow deposited orange crystals which analyzed well for [RuBr3(TMS0)4Li]2.The infrared spectrum of the dimer shows no bands attributable to the presenceof free TMSO; the bands at 1043, 1114 and 1127 cm-1, following the structuraldetermination (see Section 3.9.6), are tentatively assigned to 0-bonded, bridging andS-bonded TMSO, respectively. It seems reasonable to assume that vso of the bridgingTMSO ligands would have a stretching frequency intermediate between that found forpure S- and 0-bonded TMSO.The proton NMR of the complex in CDC13 is complicated and consists of broadmultiplets centred at .5 2.15, 2.32, 2.90, 3.53 and 4.10 ppm. The three multiplets athigher field may be due to the 0-protons of the various TMSO ligands while the two atlower field are due to the a-protons but no definite assignments can be made due to thevariety of TMSO ligands present (see below).3.9.6 The Crystal Structure of [RuBr3(TMS0)4L1]2Selected bond lengths and angles for the complex are tabulated in Table 3.10,and the ORTEP plot of the structure showing thermal ellipsoids at 50% probabilities isfound in Figure 3.10.113Figure 3.10 An ORTEP plot of [RuBr3(TMS0)41A2The compound, [RuBr3(TMS0)4Li]2, is remarkable for several reasons; notonly does the structure show four types of TMSO ligands coordinated differently but,to my knowledge, the structure is also the first to contain a sulfoxide using the 0- andS- atoms to bridge three metal atoms (see Figure 3.10). In addition, this dimer includesan example of a sulfoxide that bridges two metal centres, a bonding mode that is onlyknown in one other structurally characterized example (a Pt-S-0-K type derivativewhere S-0 = DMSO [182]) as well as both types of exclusively S- or 0-bondedsulfoxide. The only sulfoxide bonding mode not found in this structure is thebridged sulfoxide of which several examples are known [183].The structure of the dimeric complex contains a central four-membered ring,which is comprised of two Li atoms and two bridging oxygen atoms which are from two114Table 3.10 Selected Bond Lengths and Angles for [RuBr3(TMS0)4Li]2Bond Lengths (A) Bond Angles (°)atom atom distance atom atom atom angleRu Br 2.543 (ay.) Br(1) Ru(1) Br(2) 87.84(5)Ru S^2.269 (ay.) 5(1) Ru(1) S(2) 94.0(1)S(1) 0(1) 1.465(7) Br(1) Ru(1) 5(1) 174.16(8)S(2) 0(2) 1.495(6) Br(3) Ru(1) S(3) 177.02(8)S(3) 0(3) 1.491(7) Li(1) 0(2) Li(1)' 94.2(7)S(4) 0(4) 1.517(7) 0(2) Li(1) 0(2) 85.8(7)0(2) Li(1) 1.95(2) 0(2) Li(1) 0(3) 99.9(8)0(2)' Li(1) 2.05(2) 0(2) Li(1) 0(4) 131(1)0(3) Li(1) 1.94(2) 0(2)' Li(1) 0(3) 119(1)0(4) Li(4) 1.85(2) 0(2)' Li(1) 0(4) 104.2(8)0(3) Li(1) 0(4) 114.8(8)TMSO ligands (each S-bonded at the Ru centres). The molecule consists of two fac-RuBr3(TMS0)(TMS0)2 units that are centrosymmetric through the central Li202 ring.Another of the three S-bonded TMSO ligands at each of the Ru centres is coordinatedthrough the oxygen to one Li atom, each of these sulfoxides thus completing a six-membered Ru-S-0-Li-0'-S' ring. The central four-membered ring is then joined to thetwo six-membered rings. Each Ru also has one terminal S-bonded TMSO. Completingthe structure are two more 0-bonded TMSO ligands which are each only coordinated115to one Li atom. The structure is thus best formulated as [Br6(TMS0)2Ru2(p2-TMS0)2(p3-TMS0)2Li2(TMSD)2] which highlights some of the more interestingfeatures of the structure [171(b) & (c)].The geometries about the two Ru atoms are close to octahedral; all the cis anglesat Ru fall in the range 85°- 94°. The average Ru-Br bond length in the complex (2.543A) is similar to the corresponding average bond length in cis- and trans-RuBr2(DMS0)4(2.56 and 2.54 A, respectively [124,175]), and in trans-RuBr2(TMa0)4 (2.52 A,Section 3.9.4). The average Ru-S bond length within [RuBr3(TMS0)4Li]2 (2.269 A)is similar to that trans to Cl in cis-RuC12(TMS0)4 (2.275 A [171(a),172(c)]) but isshorter than those found in Ru(III)-thioether complexes which fall in the range 2.32 -2.40 A [121 and references therein].The shorter Ru-S bond lengths within [RuBr3(TMS0)4Li]2 could be the resultof more T-backbonding from Ru(II), and the ability of sulfoxides to act as moreefficient electron acceptors than thioethers [121]. The reported Ru(III)-S bond lengthsin trans-RuC14(TMS0)2- (2.33 A [172(c)]) are also longer than those within[RuBr3(TMS0)4Li]2 (2.269 A), and could be due to the stronger trans influence of themutually trans TMSO ligands within the anion or to more T-backbonding from the morebasic Ru(II) in the dimer (see Section 4.2.3, p.133, also).The S-0 bond lengths of the various nonbridging and bridging TMSO ligands(S- and 0-bonded) present within the structure vary from 1.465 to 1.517 A, whichpresumably reflects the degree of perturbation within the SO unit of the four types ofbonding TMSO ligands. The shortest S-0 bond length (1.465 A vs. 1.527 A for free116TMSO [153]) is found within the monodentate, nonbridging, Ru S-bonded TMSO, asexpected. Such shortening for S-bonded sulfoxides is consistent with other reports[171(a), 172(c)], and the bond lengths are comparable to the corresponding bonddistances within trans-RuBr2(TMS0)4 (1.466 A, Section 3.9.4) and cis-RuC12(TMS0)4(1.47 A [171(a), 172(c)] and Section 3.9.2).The two intermediate S-0 bond lengths found in /12- and P3-TMSO (1.491 and1.495 A, respectively) probably represent a compromise between the donation ofelectron density from 0 to the S-0 bond (pr-d7r donation, Section 3.4, p.64) and to theO-Ru bond. The depletion of electron density from S is compensated by donation fromthe oxygen of the sulfoxide which effectively decreases the S-0 bond distance. In thecase of the multidentate TMSO ligands, a smaller amount of electron density is availablefor donation to the S-0 bond due to the presence of the O-Ru bond, and the result is asmaller increase in the SO bond order.The SO bond length for the "pure" 0-bonded TMSO ligands (within the TMS0-Li units) is the longest (1.517 A), and is essentially the same as that found in crystallineTMSO (1.527 A [153]). The slight decrease in bond length is consistent with therationale for the bonding picture discussed in Section 3.4 (p.64) where generally the S-0bond length in 0-bonded sulfoxides is expected to decrease slightly, although in mostcases little change is seen (e.g. in the DMSO systems [107,1241).The range of bond angles around the Li atom (85.8° to 1310) indicates that thegeometry around Li deviates significantly from pure tetrahedral which probably resultsfrom steric factors due to crowding of the TMSO ligands and ring-fusion effects117[171(c)]. The presence of a distorted tetrahedral 04-donor set at Li is common[184]; the angles in the Li202 ring (85.8° and 94.2°) are significantly distortedfrom an ideal tetrahedral geometry which is probably also due to a combination of stericand ring-fusion effects; the Li-Li distance is 2.93 A [171(c)]. Another example of aLi202 ring has been reported in the literature; in this complex, the 0-atoms belong tobenzylphenyl sulfoxide, and the remaining coordination sites on the Li are filled bytetramethylethylene diamine [183]3.9.7 The Geometry of the TMSO Ligands Within the Ru(Il) ComplexesSelected bond angles within cis-RuC12(TMS0)4, trans-RuBr2(TMS0)4,[RuBr3(TMS0)4Li]2 and crystalline TMSO are tabulated in Table 3.11. Like theDMSO systems, there are only minor changes within the ligand itself whethercoordinated via S or 0 to the metal. The average C-S-0 (106°) and C-S-C (93.5°) bondangles for the TMSO ligands within the three complexes are essentially the same asthose within crystalline TMSO (106 and 93°), indicating that the overall geometry whenthe ligand when coordinated is retained.The Ru-S-0 bond angles within trans-RuBr2(TMS0)4 are slightly smaller thanthose found in cis-RuC12(TMS0)4 which indicates that there is more steric tensionpresent in the trans complex with the four TMSO ligands crowded into the "equatorialplane". The corresponding angles in [RuBr3(TMS0)4Li]2 are in the same range asthose within cis-RuC12(TMS0)4. The Ru-S-C bond angles within the TMSO ligands arelarger than 109° which indicates that the tetrahedral geometry around S becomes118Table 3.11 Selected Bond Angles for the TMSO Ligands Within the Ru(II)ComplexesAngle (°) cis - trans- [RuBr3 TMS0aRuC12(TMS0)4a RuBr2(TMS0)4 (TMS0)4Li]l2aC-S-0 107 105.5(2) 105 106C-S-C 93 93.9(2) 93 93Ru-S-0 116 113.3(1) 117Ru-S-C 118 118.1(1) 116Ru-S-C' 113Li-O-S 127.7(6)137.6(6)123.2(6)137.1(7)Ref. twb,c, [172(c)] twb twb,d 153a Average bond Angles.b tw = this work.C Published in ref. 171(a).d Published in ref. 171(b) & (c).distorted upon coordination to the metal. In addition, the two sets of Ru-S-C(C') bondspresent within the ligand in cis-RuC12(TMS0)4 are asymmetric, one angle being greaterby 5°, this could be compensation for the presence of the cis chlorines which makes themolecule less symmetrical, in contrast to trans-RuC12(TMS0)4 where the environmentof the ligands is equivalent. The Li-O-S bond angles vary from 123.2(6)° to 137.6°,and this distortion from ideal trigonal planar geometry expected for 0-bonded sulfoxide(Section 3.4, p.64) is probably due to ring-fusion effects and spatial interactions119between the TMSO ligands.3.10 Other Related Ru Reactions Involving DMSO or TMSOIn addition to the ruthenium complexes of DMSO and TMSO discussed in thischapter, other relevant details from reports which appeared during the course of thisthesis work will now be reviewed in Sections 3.10.1 - 3.10.3, to make the materialcovered in this field of chemistry as comprehensive as possible.3.10.1 Related Reactions Involving DMSOThe procedures reported for the synthesis of Ru2C16(DMS0)4, fac- and mer-RuC13(DMS0)3 [119(b)] have been repeated by workers in this laboratory but, in lieuof the fac- and mer-complexes, [H(DMS0)2][trans-RuC14(DMS0)2] and mer-RuC13(DMS)3 were isolated instead [121]. The procedure for the dimeric complex[119(b)] would sometimes yield trans-RuC12(DMS0)4 [121], and at other times thedimeric complex (see Section 3.8.6). The procedure reported for the synthesis ofRuBr3(DMS0)3 [119(c)] was also repeated but the corresponding dimethylsulfidecomplex, RuBr3(DMS)3, was isolated instead [121]. Analogous procedures with TMSOyielded the corresponding TMS complexes ([171(a)] and Section 3.10.3).The synthesis of RuC13(DMS0)3 was first reported in the early 1970s [144], butwas later retracted because the reaction was not reproducible [108]. A complex with thesame formulation with all 0-bonded DMSO ligands was subsequently reported in theliterature [185]. In 1988, the isolation of mer- and fac-RuC13(DMS0)3 was reported120on the basis of elemental analysis and limited spectroscopic data (UV-Vis and IR)[119(b)]. The mer complex has since been synthesized and structurally characterized[157], but the accompanying spectroscopic data do not match those in the 1988 report[119(b)]. In fact, the data (Uv-Vis and IR) reported for mer-RuC13(DMS0)3 in ref.119(b) are closer to those reported for mer-RuC13(DMS)3 [121] (which was structurallycharacterized), although the reported elemental analysis in ref. 119(b) matches that ofthe DMSO complex better!The reaction procedures reported for mer and fac-RuC13(DMS0)3 [119(b)]consist of heating acidified solutions of DMSO containing RuC13.3H20 at differenttemperatures. The use of lower reaction temperatures (70-80°C) was reported to givethe fac isomer, and the use of higher temperatures (130-150°C) the mer isomer[119(b)]. Subsequent reports [121,157], however, indicated that the protonated-DMSOionic complex, [H(DMS0)2][trans-RuCI4(DMS0)2], was formed using the lowertemperatures. Similar reaction conditions but with a higher temperature yielded thethioether complexes, RuX3(DMS)3 (X = Cl, Br; see Section 3.10.3). The protonatedDMSO complex was isolated by workers in this group [121] using procedures identicalto those reported for the synthesis of fac-RuC13(DMS0)3, in which acidified solutionsof RuC13.3H20 in DMSO are heated at 70-80°C [119(b)]. The Trieste group isolate thesame ionic complex with a slight modification of the reaction procedure (an ethanolicsolution of RuC13.3H20 is refluxed and concentrated before being acidified and heatedat 80°C).The Trieste group subsequently isolated mer-RuC13(DMS0)2(DMS0) by121refluxing solutions of [H(DMS0)2][trans-RuC14(DMS0)2] in acetone with DMSO [157]and, in doing so, replaced a a- by DMSO to obtain the neutral Ru(III) species. TheRu(III) complex, mer-RuC13(DMS0)2(DMS0) is reported to undergo a "spontaneous"one-electron reduction in hot DMSO (under Ar) to form trans-RuC12(DMS0)4 [157].The reducing agent in this reaction is thought to be DMSO which is oxidized todimethylsulfone; the required stoichiometric amount of dimethylsulfone has beendetected using gas chromatography in the reduction of mer-RuC13(DMS0)3 by DMSO[157]. This reaction is also thought to be one of the steps leading to the isolation ofRu(III)-thioether complexes following similar reaction procedures but with highertemperatures [121,171(a)] (see Section 3.10.3).Reports on the synthesis [119(c)], reactivity and catalytic activity [120] ofRuBr2(DMS0)3 have also appeared in the literature. The synthetic procedures wererepeated by the UBC group (including part of this thesis work) and by the Trieste groupbut different complexes were obtained in each case. In this group, the reportedprocedure [119(c)] was followed as closely as possible (a ethanolic solution containingRuC13.3H20, excess LiBr and DMSO was refluxed, and the complex isolated byconcentration of the reaction solution and the addition of acetone) to yield a yellowprecipitate which, after recrystallization (Et0H/acetone, 2:1 v/v), analyzes well forRuBr2(DMS0)4; spectroscopic data (see Section 3.8.2(b)) suggest that the complex istrans [171(c)] .The Trieste group, however, reported [172(a)] that following the literatureprocedure [119(c)], without any subsequent recrystallization steps, yielded a mixture of122Li[fac-RuClnBr 3_n(DMS0)3] (n = 0-3) species. Recrystallization of the mixture in aMe0H/LiBr solution, moreover, resulted in the isolation of Li[fac-RuBr3(DMS0)3][172(a)]. The recrystallization procedures are crucial in the isolation of the final productas it appears that Li can be "washed out" as a halide salt depending on the conditionsused.The synthetic route reported by Poddar's group [119(b)] to "RuBr2(DMS0)3"almost certainly yields a mixture containing the chloro, the bromo and mixed halidelithium derivatives. The catalytic properties and results attributed to "RuBr2(DMS0)3"[120] are dubious and should be interpreted with caution.3.10.2 Related Reactions Involving TMSOThe synthesis of RuX2(TMS0)4 complexes (X = Cl, Br, I) was first reportedin 1978 [118] although no structural data were available. The cis-dichloro ([171(a)],Sections 3.9.1(a) and 3.9.2) and trans-dibromo (Sections 3.9.3(b) and 3.9.4) complexeswere subsequently structurally characterized as part of this thesis work. The Triestegroup has also published structural details on the cis-dichloro complex and reportedalternative synthetic routes to the dichloro and dibromo complexes [172(c)].Reports on two other Ru-TMSO complexes, [H(TMS0)][trans-RuC14(TM50)2]and mer-RuC13(TMS0)2(TMS0), have also appeared in the literature [172(c)] and areof interest because they are the first known examples of Ru(III)-TMS0 complexes. Inaddition, the synthetic procedures leading to these complexes show striking similaritiesto those used to synthesize the DMSO analogues [121,157] (Section 3.10.1). The123common element within the synthetic procedures for the generation of theseprotonated/ionic DMSO and TMSO complexes appears to be the heating (70-80°C) ofstrongly acidified solutions of RuC13.3H20 in the appropriate sulfoxide [121,172(c)].Workers in this group heated a solution of RuC13.3H20 in acidified DMSO at 70°C[121], while the Trieste group added acid and DMSO to a concentrated solution ofRuC13.3H20 in ethanol [157]. The ionic complexes precipitated when the reactionmixtures were cooled to room temperature, and acetone was added.Replacement of a CV in the anionic species, [trans-RuC14(TMS0)2I, by TMSOgives the neutral Ru(III) complex, mer-RuC13(TMS0)3 [172(c)]; the replacement of oneCV by DMSO has also been observed in the protonated DMSO-Ru(III) complex [157)]and in the Rh(III) complex, [H(DMS0)2][trans-RhC14(DMS0)2], to generate the neutralmer-RhC13(DMS0)3 complex [186].3.10.3 Ru -Thioether Complexes from Reactions with DMSO and TMS0The isolation of RuX3(thioether)3 (thioether = TMS or DMS) from reactionsof RuC13.3H20 with acidified DMSO or TMSO was reported by workers in this group[121,171(a)] using the procedures previously reported [119(b) & (c)] forRuC13(DMS0)3 and RuBr3(DMS0)3 (see also Section 3.10.1 and 3.10.2). Thesynthetic procedures for the thioether complexes were similar to those which yielded theprotonated DMSO and TMSO complexes except that a higher reaction temperature wasused (130-140°C vs. 70-80°C). The use of relatively higher temperatures with stronglyacidified solutions of RuC13.3H20 in DMSO or TMSO appears to generate the124corresponding Ru(III)/DMS or TMS complexes [121,171(a)].Formation of the thioether in these reactions is thought to be due to redoxprocesses involving Ru(III) and the sulfoxide. Commercially available RuC13.3H20analyzes for the ratio of elements in its formulation but actually consists of a mixtureRu(III) and Ru(IV) species of which the latter is thought to be a hydroxo species[187]. The exact mechanistic steps leading to the reduction of the sulfoxide are notknown, but there is evidence which indicates that the reactions shown in equations 3.1and 3.2 may play a role.2Ru(III) + DMSO + H20 -> 2Ru(II) + DMS02 + 2H+^(3.1)2Ru(III) + R2S + H207-k2Ru(II) + R2S0 + 2H+^(3.2)The reduction of Ru(III) to Ru(II) with the concomitant oxidation of DMSO to thesulfone (eq. 3.1) was initially suggested by Ledlie et al. [188], and the Trieste grouphas subsequently detected the presence of dimethylsulfone (in stoichiometric amounts)in the reduction of RuC13(DMS0)3 (in DMSO under Ar) to trans-RuC12(DMS0)4[157]. Evidence for the second equilibrium (eq.3.2, R = nBu) was reported by Ledlieet al. [188] and, under highly acidic conditions, the reaction is likely pushed to the left-hand side, thereby generating the thioether [121]. The ligand sets on Ru during theprocess, however, remain undefined, and more studies are required before themechanistic steps in this new route to thioether complexes are fully understood[121,171(a)].125Chapter 4: Sulfoxide Complexes of Ruthenium Other Than Those ofDMSO and TMSO: Other Monodentate and Bidentate SulfoxideLigand Systems4.1 IntroductionThis chapter is concerned with sulfoxide complexes of ruthenium other thanthose of DMSO and TMSO (discussed in Chapter 3). Like the complexes of DMSO andTMSO, a variety of structural types was isolated with the monodentate sulfoxides used(Et2S0, nPr2S0, nBu2S0, MePhS0 and Ph2S0), and these complexes are discussedin the first part of the Chapter (Sections 4.2 - 4.2.8). The chelating sulfoxide complexesof Ru obtained in this present work are of the two types cis and trans-RuC12(R(0)5(CH2)nS(0)R)2, and are discussed in the later part of the chapter (Sections4.3 - 4.3.6).Relevant data from the literature are also included in order to cover the materialin this chapter as comprehensively as possible. Where structures of the complexes havebeen determined, selected bond data are tabulated in the text; full experimentalcrystallographic details can be found in Appendix D although structure factor tables arenot included.4.2 Monodentate Sulfoxide Complexes of Ruthenium4.2.1 Ru2C15(Et2S0)4Diethylsulfoxide was refluxed with the "ruthenium-blue" solutions (Section1262.4.1, p.45) under H2 in a manner analogous to the procedures used for synthesizingcis-RuC12(DMS0)4 and cis-RuC12(TMS0)4. The isolated complex was not, however,a monomeric Ru(II) species but a dinuclear Ru(II)-Ru(III) species, which was surprisinggiven that DMSO and Et2S0 differ only by one carbon in their respective alkyl groups.The ethyl groups of Et2S0 are possibly sterically more demanding than the methyls onDMSO and prevent the formation of a monomeric tetrakis(sulfoxide) complex. The titlecompound analyzes well (C, H and Cl) for the proposed formulation, and the molecularweight was found to be 836 g/mol using the Signer Method [139] (vs. a calculatedmolecular weight for the dimer of 803 g/mol). Attempts to determine the molecularweight using mass spectroscopy were unsuccessful; no parent peak was obtained usingeither El (electron ionization) or FAB (fast atom bombardment). The most intense peakwas observed at 106, corresponding to free Et2S0. Attempts to grow a crystal of thecomplex were unsuccessful, although various methods (use of slow diffusion, saturatedsolutions, slow evaporation) were tried.The 1H NMR spectrum of the complex in CD2C12 at 20°C consists of a broadtriplet at S 1.41 ppm and a broad, unresolved multiplet at (5 2.86 ppm. The triplet isassigned to the methyl group, and the multiplet to the diastereomeric methylenes ofdiethylsulfoxide. The broadness of the peaks is due to the presence of the d5 Ru(III)centre which exhibits paramagnetism. The magnetic moment of the complex wasdetermined using the Evans method [138] to be 1.2 BM which is lower than the valueexpected for one unpaired electron (1.73 BM [189]). This discrepancy is likely dueto errors in the method induced by the use of small ( < 3 mg) amounts of the127compound; more concentrated samples could not be used because of the poor solubilityof the complex. While the degree of paramagnetism could not be determinedunambiguously, the complex was shown to be paramagnetic beyond a doubt by the shiftsof the reference peaks in the 1H NMR spectrum measured during the Evans experiment.The proton NMR signals of free diethylsulfoxide (6 1.25 and 2.62 ppm for themethyl and methylene groups, respectively) are shifted downfield upon coordination toRu (6 1.41 and 2.86 ppm). The magnitudes of the shifts (0.16 and 0.24 ppm) perhapsimply that the sulfoxides are coordinated through 0 (see Section 3.6.1, p.68), althoughthis ignores the effects of paramagnetism. The infrared data indicate the presence of S-bonded sulfoxides (see below). No free sulfoxide was detected in solution.The infrared vso of free Et2S0 is shifted to higher frequencies when coordinatedto the metal in the complex (1001 --0 1071 cm-1) which is consistent with S-bondedsulfoxides (Section 3.4, p.64). No strong bands were seen in the 1000 cm-1 regionindicating the absence of free or 0-bonded sulfoxides. A band in the IR spectrum at 326cm-1 is tentatively assigned to the terminal chlorides. No bands at wavelengths below250 cm-1 could be assigned to the bridging chlorides due to the poor resolution of thespectrum. The infrared data in this case are considered more convincing than those ofthe 1H NMR for two reasons. The magnitude of the effects due to coordination of thesulfoxide tend to be greater in the infrared than in the 1H NMR spectrum. Secondly,the NMR shift effects on the protons more than one atom away from the sulfur diminishquickly, and so changes in the chemical shifts of the methyl group of Et2S0 whether0- or S-bonding are likely to be small.128The proposed structure for this compound is a triply chloro bridged dimer withall terminal S-bonded sulfoxides arranged symmetrically around the Ru centres. A morecomplex 1H NMR spectrum would be expected if the sulfoxides were unsymmetricallycoordinated. The molar conductivity of the complex in nitromethane (4.9 ohm-1 mo1-1cm2) indicates that the complex is essentially non-conducting in this solvent.No Et2S0 complexes have been obtained to date by direct reaction ofRuC13.3H20 with the sulfoxide, the product of these attempts being oils which yieldno isolable products; similar attempts by the Trieste group have not met with anysuccess either [190].The only known example in the literature of a Ru/diethylsulfoxide complex thathas been structurally characterized is [RuBr3(N0)(Et2S0)]2 [113]. The dimer consistsof two Ru atoms with approximately octahedral geometry, bridged by two bromines.Each Ru atom, in addition, has two terminal bromines, and a nitrosyl and adiethylsulfoxide ligand coordinated through N and 0, respectively. Several points ofinterest arise from the structure.The S-0 stretching frequency of free diethylsulfoxide decreases (1001 -- 920cm-1), indicating that the SO bond order decreases slightly upon coordination [113].The S-0 bond distance within the Et2S0 ligands in the dimer (1.541 A [113]) iscomparable to that for 0-bonded DMSO in cis-RuC12(DMS0)4 (1.537 A, Table 3.2,p.63). The change in the S-0 bond length within DMSO, when 0-bonded, is small, thecorresponding bond length in free DMSO being 1.531 A (Table 3.1, p.61). The factorscontributing to the length of the S-0 bond length in the 0-bonded Et2S0 systems are129probably similar to those in DMSO complexes (e.g. see Table 3.2, p.63), and so the5-0 bond length of 0-bonded Et2S0 in the dimeric complex (1.541 A) [113] can likelybe used as an approximation for the same bond in free, crystalline Et2S0.The short Ru-N bond length (1.71(1) A [113]) between the nitrosyl ligand andthe metal centre indicates the presence of strong 7-backbonding between NO and Ru.Sulfoxides are not known to be strong T acceptors [104(a)], and so the nitrosyl ligandcompetes more effectively for electron density on the metal. The withdrawal of electrondensity from the Ru centre by the NO ligand and Ru(III) centre results in a relatively"harder" metal centre which makes a Ru-O interaction more favourable (Section 3.5,p.67). The observed 0-bonded Et2S0 ligands are thus the result of steric and electronicfactors present in the compound.The average Ru-O-S bond angle within [RuBr3(N0)(Et2S0)]2 (123.9° [113]) isin keeping with those within other 0-bonded sulfoxides (Tables 3.2 (p.63), 4.1 and 4.2)which are believed to have sp2 hybridized oxygens (Section 3.4 p.64). The C-S-C and0-S-C bond angles within the ligand (102° and 103.1°, respectively [113]) arecomparable to those found in other 0-bonded sulfoxides (e.g. 0-bonded DMSO in cis-RuC12(DMS0)4, 99.0° and 102.9°, respectively, Table 3.2, p.63). The correspondingangles in free DMSO differ by only a small amount indicating that 0-bonding has aminimal effect on sulfoxides as expected (see Section 3.4, p.64). The structure of free,crystalline Et2S0, by extrapolation, is likely to be similar to that of the coordinatedligand found within the dimer.1304.2.2 [H(nPr2S0)2]+ [trans-RuC14(nPr2S0)2IThe isolation of an ionic, Ru(III) species, [H(nPr2S0)2]+[RuC14(nPr2S0)21,from the reaction of nPr2S0 and the "ruthenium-blue" solutions (see Section 2.4.1,p.45) under H2 was surprising given the reducing conditions of the reaction procedure.The subsequent workup of the reaction was carried out under Ar, and the orangecomplex precipitated slowly from the reaction solution which was stored under Ar.Oxidation of Ru(II) to (III) may have been caused by air diffusing into the system butthis is considered unlikely. The sulfoxide, nPr2S0, may have acted as the oxidizingagent and become reduced to the corresponding sulfide following the refluxingprocedures. Reduction of the sulfoxide could be accompanied by oxidation of Ru(II) toRu(III). Redox equilibria similar to those discussed in Section 3.10.3 (p.124) may haveplayed a role in the eventual formation of the Ru(III) species. The reaction was repeatedwith subsequent exposure to air following the refluxing procedures; the colour of thesolution changed slowly from orange to green but no complex could be isolated fromthe green solution.Analogous ionic compounds of DMSO and TMSO have also been reported andwere prepared by heating acidified solutions of RuC13.3H20 in the appropriatesulfoxide at 70-80°C [121,172(c)]. The use of higher temperatures (130-150°C) led tothe isolation of the Ru(III) DMS and TMS complexes, RuC13(thioether)3 [121,171(a)],which are discussed in Section 3.10.3. The reaction of Ph2S0 with the "ruthenium-blue" solutions also led to the isolation of a Ru(III) species (Section 4.2.7, p.146).The proton NMR spectrum of [H(nPr2S0)2]±[trans-RuC14(nPr2S0)2I in131CD2C12 is uninformative due to the paramagnetism of the Ru(II1) centre; broad,unresolved peaks are observed which are attributed to the protonated cation. A solutionof the complex in nitromethane (10-3 M) has a molar conductivity of 7.7 ohm-1 mol-1cm2 which is surprising given the ionic nature of the complex, as values in the range20-30 ohm-1 mol-1 cm2 are the norm for 1:1 electrolytes in this solvent [191].Presumably, the complex remains as an associated ion pair in nitromethane resulting inthe low conductivity values observed. A similar result was reported for the molarconductivity of the DMSO analogue, [H(DMS0)2] + [RuC14(DMS0)2]-, in the samesolvent (9 ohm-1 mol-1 cm2 [121]) and is comparable to that of the n-propylsulfoxidecomplex.The infrared spectrum of free nPr2S0 occurs at 1015 cm 1 (uso) while that ofthe complex has strong absorption bands at 1093 and 1015 cm-1 which are assigned tothe S-0 bond of the nPr2S0 S-bonded to Ru and that of the protonated nPr2S0,respectively. The increase in stretching frequency observed for S-bonded 1Pr2S0 ligandis consistent with S-bonded sulfoxides, while us° of the protonated nPr2S0 ligandsshows no change (Section 3.4, p.64). In addition, the infrared spectrum of the complexin the solid state exhibits a broad band medium intensity band in the region 1100 to1600 cm-1 and a more intense broad band centred at 734 cm-1. These features in theinfrared spectra are characteristic of 0-11-0 systems and have also been observed inthe infrared spectra of the Ru/Rh-DMSO analogues [121,192,193].1324.2.3 The Crystal Structure of [H(nPr2S0)2]+[trans-RuC14(nPr250)2ISelected bond lengths and angles for the structure of the title complex aretabulated in Table 4.1; the complete data set for this structure is included in AppendixD. Figure 4.1 shows an ORTEP structure for the cation and anion of the complex, 50%probability thermal ellipsoids being shown for the non-hydrogen atoms.Table 4.1^Selected^BondRuC14(nPr250)2]Lengths and^Angles^for^[H(nPr2S0)2][trans-Bond Lengths (A) Bond Angles (*)atom atom distance atom atom atom angleRu(1) C1(1) 2.3549(8) C1(1) Ru(1) C1(1)' 180.00Ru(1) C1(2) 2.3533(8) C1(1) Ru(1) S(1) 87.51Ru(1) S(1) 2.390(1) C1(1) Ru(1) C1(2) 91.55(3)S(1) 0(1) 1.471(2) C1(1) Ru(1) S(1)' 92.49(3)S(2) 0(2) 1.559(2) C1(2) Ru(1) C1(2)' 180.000(2) H(15) 1.216(3) S(1) Ru(1) s(1) 180.000(1) S(1) C(1) 106.7(2)0(2) S(2) C(7) 102.3(2)0(2) S(2) C(10) 103.5(2)C(7) S(2) C(10) 99.9The crystal structure of this complex consists of [H(nPr2S0)21+ cations andtrans-RuC14(nPr2S0)2 anions held together by electrostatic forces. The unit cell is133•C.5tZ •4, •0360."Rut(14^• IN•N •^• s^'16. •• Vt•S IC411- • ChVW,C I Z411) •it, • vorC3C lcomprised of one trans-RuC14(nPr2a0)2- anion and one half each of two nPr2S0molecules from two cations adjacent to the nPr2S0 ligands bonded to Ru. The crystalis triclinic and belongs to the P1 space group. The anionic part of the complex showsalmost perfect octahedral geometry at the Ru(III) centre with trans angles of 180.00°across the axial bonds, and cis angles ranging from 87.51(3) to 92.49(3)° (Table 4.1);the two nPr2S0 ligands on the anion are eclipsed.Figure 4.1 An ORTEP plot for the complex [H(nPr2S.0)2][trans-RuC14(nPr2S0)2]There are two other structurally characterised examples of protonated sulfoxidecations known in the literature; the [H(DMS0)2]+ cation which occurs together withtranstM(III)C14(DMS0)2I (where M = Rh [193] and Ru [121,124], and the[H(TMS0)]4- cation which exists in conjunction with the [trans-Ru(III)C14(TM50)2Ianion [172(c]. A brief report on the [H(nPr2S0)2]+[trans-RhC14(1Pr250)2]- complex134has appeared in the literature although no structural data were reported [193]. Selectedbond lengths for the anionic Ru(III)-DMSO/TMSO/nPr2S0, neutral Ru(III)-DMS/TMSand neutral trans-Ru(II)/Br/C1-TMSO/DMS0 complexes are tabulated in Table 4.2 forcomparison, and some details are discussed below.The two kinds of bonded nPr2S0 molecules present within the title complexprovide valuable information on the nPr2S0 molecule, the structure of which (as suchor as a ligand) has not appeared in the literature. The average C-S-C and 0-S-C bondangles (99.9° and 102.9°, respectively) within the protonated nPr2S0 cation arecomparable to those found in the protonated DMSO cation (101.2° and 102.7°[172(b),121]) and in other 0-bonded sulfoxides [107,113]. The corresponding C-S-Cbond angles within free DMSO, compared to those within [H(DMS0)2]+, are slightlydiminished and the 0-S-C bond angles slightly greater (Table 3.1, p.61). The protonatedform of nPr2S0 can thus probably be used to approximate the structure of the free,crystalline sulfoxide because 0-bonded sulfoxides suffer little perturbation from theirgeometry (Section 3.4, p.64) in the "free" state. The SO bond length of free nPr2S0is thus likely to be similar to that of the protonated ligand (1.559(3) A), and can be usedto make comparisons with the length of the S-bonded ligand in the anion.The average Ru-Cl bond length in [trans-RuC14(nPr2S0)2]- is slightly longerthan those in the DMSO/TMSO analogues and those of the mer-RuC13-DMS/TMScomplexes (Table 4.2), and seems typical for Ru(III)-C1 bond lengths. Thecorresponding bond lengths within trans-RuC12(DMS0)4, a Ru(II) species, are longerdue to the larger ionic radius of Ru(II) [194].135The SO bond length (1.471 A) within [trans-RuC14(nPr2S0)2I is comparableto the corresponding bond lengths in the DMSO and TMSO analogues but isconsiderably shorter than that found in the protonated nPr2S0 ligand (1.559 A,Table 4.2). The shortening of the SO bond length in the S-bonded ligand is typical ofS-bonded sulfoxides (Section 3.4, p.64).Of some interest, the Ru-S bond length in [trans-RuC14(nPr2S0)2I issignificantly longer than the corresponding average bond lengths in the DMSO andTMSO analogues which themselves are comparable to the Ru-S bond lengths foundwithin trans-Ru(II)-DMSO/TMS0 complexes (where the sulfoxides are all S-bonded andmutually trans, see Table 4.2). The Ru-S bond length within the Ru(III)-nPr2S0complex is, however, comparable to those found in mer-RuC13(thioether)3 wherethioether = TMS or DMS (Table 4.2).The comparable Ru-S bond lengths within the Ru(II) and anionic Ru(III)DMSO/TMSO systems can be rationalized by considering two factors which effectivelyneutralize each other [121]. The ionic radius of the low spin Ru atom decreases byabout 0.04 A when the oxidation state increases from II to III [194] and should resultin a shorter Ru(III)-S bond length relative to that of the Ru(II)-S bond. The expectedlonger Ru(II)-S bond lengths are, however, offset by the higher 7-basicity of Ru(II)[121] which compensates for the larger ionic radius of Ru(II) species. The expecteddifference between the Ru-S bond lengths of the Ru(II) and Ru(III) systems is thusdecreased to a point where the bond distances are comparable, the Ru(II) bonds beingslightly longer (Table 4.2).136Table 4.2 Selected Bond lengths for Some Sulfoxide and Thioether Complexes ofRu(II) and Ru(III)[H(sulfoxide)21[trans-RuC14(sulfoxide)21^mer-RuCI3(thioether)3Bond^DMSO^TMSO^nPr2S0^DMS^TMSRu-CI^2.338^2.347^2.354^2.344^2.345S-0^1.467^1.477^1.471Ru-S^2.348^2.331^2.390^2.393^2.384S-0^1.533^1.589^1.559Ref.^121,172(b)^172(c)^twa^121^171(a)trans-RuX2(sulfoxide)4Bond^X=CI, DMSO X=Br, DMSO X=Br, TMSORu-CI^2.42S-0^1.466^1.484^1.491Ru-S^2.353^2.360^2.3345Ref.^121,124^175 twa,batw = this work.bDiscussed in Section 3.9.3(b).The Ru-S bond distances within the Ru(III)-thioether (DMS and TMS) complexesare greater than the corresponding bonds in the ionic Ru(III)-DMSO/TMS0 complexes(Table 4.2) and in mer-RuC13(DMS0)2(DMSO) (2.34 A [172(b)]). This may beattributed to TMS and DMS being poorer 7-electron acceptors than the correspondingsulfoxides [121]. The Ru-S bonds within the thioether complexes are longer than thosein the Ru(II)-DMSO/TMS0 systems for the same reason, in addition to the higherbasicity of Ru(II). From the data tabulated in Table 4.2 for Ru-S bond lengths, it137appears that, as a 7r-electron acceptor, nPr2S0 is comparable to DMS and TMS and iscertainly poorer than DMSO and TMSO. To some extent, the ability of a ligand toaccept 7r-electrons back-donated by a metal centre is dependent on the degree of electrondensity present on the ligand. The longer propyl chain of 7ZPr2S0 is more likely tocontribute a greater degree of electron density to S than the methyls or methylenes inDMSO and TMSO, respectively. Larger amounts of electron density on S would leadto a reduction in backbonding from Ru, and a longer Ru-S bond would be expected.Another consequence of increased amounts of electron density on S would be areduction in the contribution of electron density from 0 (see Section 3.4, p.64).Effectively, this should reduce the degree of shortening associated with the SO-bond asthe alkyl substituent increases in length. However, this trend is not observed within theprotonated DMSO and nPr2S0 complexes where the SO-bond lengths are almost thesame. The degree of shortening, estimated by taking the difference between the SObond distance of the protonated and S-bonded sulfoxides for each ligand, shows theopposite trend; the S-0 bond length in the DMSO complex decreases less than that inthe nPr2S0 complex (0.066 vs. 0.088 A, respectively). This observation tends tosuggest that such arguments involving the relative contribution of electron density bythe substituent on the SO moiety may not be too significant in determining the bonddistance of the Ru-S bond in these complexes.Steric factors could conceivably affect the length of the Ru-S bond in the Ru(III)-sulfoxide complexes. DMSO has a larger cone angle than TMSO [171(a),172(c)] andis therefore sterically the more demanding of the two sulfoxides. The Ru-S bond lengths138within the anionic Ru(III)- DMSO (2.348 [193,121,124]) and -TMSO (2.331 A [172(c)])complexes indicate that the DMSO ligands are slightly further away from the metalcentre due to the greater steric demands of DMSO. The nPr2S0 ligand is almostcertainly less easily accommodated than DMSO and, in consequence, is the moststerically demanding of the three sulfoxides and is likely to be the major reason for thesignificantly greater Ru-S bond length found in the nPr2S0 complex.The cationic constituent of the complex, [H(nPr2S0)2]±, is the third knownexample of such protonated sulfoxide cations with accompanying crystallographic data,the other two being [H(DMS0)2]+ [121,124,193(a)] and [H(TMS0)] + [172(c)]. Thesynthesis of [H(nPr2S0)2][RhC14(nPr2S0)2], the Rh analogue of the title complex, wasalso reported previously [193] although no structural data were available. The SO bonddistances within the protonated DMSO (1.533 A [121,124]) and TMSO (1.589 A[172(c)]) cations are both longer than those in the free ligands (1.531 (Table 3.1, p.61)and 1.527 A [153], respectively). The lengthening of the SO bond is consistent withcoordination through or protonation at the oxygen of sulfoxides [107,121,172(c)] andreflects the change in hybridization of the oxygen towards sp2 and more single bondcharacter [104(a),172(c)] (see also Section 3.4, p.64). The SO bond length within the[H(11Pr2S0)2]+ cation is 1.559 A and is probably slightly longer than that in freenPr2S0 on the basis of the changes observed for the DMSO and TMSO analogues.The 0-0 bond length within the protonated nPr2S0 cation (2.432 A) iscomparable to that found within the DMSO complex (2.42 A) [121,124], and bothlengths are consistent with strong and nearly symmetrical 0-0 bonds which typically139have lengths in the range 2.4 - 2.5 A [4,195]. The two 0-H bond distances in the[H(1Pr2S0)2]± cation are equidistant (1.216 A) while those in the DMSO analoguediffer considerably (1.30(6) and 1.12(6)A [121,124,193(a)]). The two sets of C-S-0bond angles on either side of the proton in the propyl cation (102.3(2) and 103.5(2)°)indicate that the 0--0 unit is not completely symmetric. The DMSO analogue is,however, even less symmetric with corresponding bond angles of 102.5 and 105.5°[121,172(b), 193(a)].4.2.4 Ru2CI5 (n Pr"2"-"5The direct reaction of RuC13.3H20 with nPr2S0 resulted in the isolation of ayellow crystalline precipitate that was deposited on the sides of the reaction flask aftera few months. The precipitate analyzes well (C, H and Cl) for a Ru(II)-Ru(III) "dimer"with the above formulation. A molecular weight of 1112 g/mol was determined for thecomplex using the Signer method [139] compared to the theoretical molecular weightof 1049.7 g /mol. Attempts to determine the molecular weight using mass spectroscopy(El and FAB) were unsuccessful; the only peaks seen in the FAB spectrum were dueto the matrix and free nPr2S0.The 1H NMR spectrum of the complex in CD2Cl2 consists of six broad andoverlapping multiplets. Two sets of triplets at (5 1.05 and 1.15 ppm (with an integrationratio of 4:1, respectively) are assigned to the methyl groups of the sulfoxide which inthe free ligand have a resonance at 6 1.0 ppm. The magnitude of the downfield shiftsis generally indicative of 0-bonded sulfoxides (Section 3.4, p.64), although the effects140of coordination are likely to be diminished at the 7 position and have little effect on theNMR properties of the C-H bond. The presence of 0- and/or S-bonded sulfoxides inthis compound cannot be definitively assigned using 1H NMR. The infrared data forthe complex indicate, however, that both 0- and S-bonded sulfoxides are present (seebelow).The triplets at 6 1.15 and 1.05 ppm are tentatively assigned to S- and 0-bondednPr2S0, respectively, because the effect of coordination through S on the S-C bond isgreater, and thus the methyl group would be shifted further downfield (Section 3.4,p.64). The integration ratio of the triplets suggests that four of the five nPr2S0 ligandsare S-bonded and the remaining one 0-bonded. This assignment is, however, tentativein the absence of structural data. The two multiplets at 6 1.70 and 1.97 (total H 24) areboth broad and probably arise from the methylenes of the propyl groups within the S-bonded ligands overlapping with the 0-bonded diastereomeric methylene protons. Theremaining two multiplets at 6 3.34 and 4.15 ppm are considered to be due to thediastereomeric methylene protons of S-bonded nPr2S0 ligands.The infrared spectrum of the complex in the solid state indicates the presence ofboth 0- and S-coordinated nPr2S0 ligands. The infrared stretching frequency for theSO moiety in free nPr2S0 occurs at 1015 cm-1, and the observed bands at 1014 cm-1and 1093 cm-1 for the complex are assigned to 0- and S-bonded nPr2S0, respectively(see Section 3.6.2, p.70).Steric effects could account for the possible presence of one 0-bonded sulfoxidein the dinuclear nPr2S0 complex. The propyl group of the sulfoxide is perhaps less141easily accommodated than the methyl groups in cis-RuC12(DMS0)4 [107], or the ethylgroups in Ru2C15(Et2S0)4 (Section 4.2.1) which only has four sulfoxides per "dimer".The nPr2S0 complex, however, has five sulfoxides per "dimer" which probably makesthe Ru centres too sterically hindered to accommodate all S-bonded sulfoxides. Atentative structure for the complex is (C1)(nPr2S0)3RuOther known examples of Ru/nPr2S0 complexes are RuX3(nPr2S0)3 (X = Cland Br) [117,118] which were reported in the literature in the late 1970s and werecharacterized by elemental analysis and infrared spectroscopy; no structural data for thecomplexes were reported. The infrared data indicated that both 0- and S-bondedsulfoxide ligands were present in the chloro and bromo complexes, and conductivitydata indicated that the complexes were non-conducting in MeCN. The calculated C, Hand Cl values for RuC13(nPr2S0)3 are in the same range as those for Ru2C15(nPr2S0)5but there is a difference of 1.1% and 0.6% in the C and Cl values, respectively.Ru2C15(nBu2S0)5The reaction of nBu2S0 with the "ruthenium-blue" solutions (see Section 2.4.1,p.45) resulted in the isolation of a yellow precipitate which analyzed well (C, H, andCl) for the dinuclear formulation, Ru2C15(nBu2S0)5. The theoretical molecular weightof the complex is 1189.7 g/mol, and the molecular weight determined by the Signermethod [139] was 1075.0 g/mol. The 9% error is probably due to the small amountsof complex used (1.3 mg); unfortunately, the poor solubility of the complex preventedthe use of larger amounts. The complex was submitted for mass spectroscopic analysisII, 2_v2 C1)2Runi(C1)2(nPr2S0)2.142but again the parent peak could not be obtained using either El or FAB.The 1H NMR spectrum of the complex in CD2C12, like those of the otherRu(II)/(III)dinuclear species, is poorly resolved and consists of broad peaks. The tripletdue to the methyls of the butyl chain is shifted downfield slightly to b 1.00 ppm (from,5 0.98 ppm in the free ligand) upon coordination to the metal. As in Ru2C15(nPr2S0)5,the effects on the sulfoxide due to coordination of the sulfoxide through S diminishquickly as the length of the chain increases. The observed chemical shifts in the 1HNMR spectra thus cannot be used to assign definitely the sulfoxides as either S- or 0-bonded.The two multiplets centred at .5 3.42 and 4.15 ppm are assigned to thediastereomeric a-protons of S-bonded nBu2S0. In the 1H NMR spectra of the freesulfoxide, the a-protons appear as an unresolved multiplet centred at 6 2.54 ppm, butthe resonances appear to be split and shifted further downfield upon coordination. Themagnitude of the downfield shift and increase in inequivalence are both consistent withS-bonded sulfoxides (Section 3.6.1, p.68). In contrast, the multiplets (centred at 6 2.75ppm), considered to be due to the a-protons of nBu2S0, shift downfield only slightlyupon coordination of the sulfoxide through 0. The inequivalence of the protons remain"unchanged" unlike those of the S-bonded ligand, and the magnitude of the shift isconsistent with 0-bonded sulfoxides (Section 3.6.1, p.68). The integration ratio for thetwo sets of multiplets (S-bonded and 0-bonded) is roughly 4H to 1H which implies that4 of the sulfoxides are S-bonded and the remaining one is 0-bonded. No free sulfoxideswere observed in solution.143The infrared stretching frequency of the S-0 bond in the free ligand appears at1022 cm4. Two strong bands are observed in the infrared spectrum of the complex inthe solid state at 1107 cm-1 and 1020 cm4; the former is assigned to S-bondednBu2S0, and the latter to 0-bonded (Section 3.4, p.64). The reasons for the onepossibly 0-bonded nBu2S0 in the complex are probably the same as those discussedfor the corresponding dinuclear nPr2S0 complex (Section 4.2.4). The butyl group isprobably even less easily accommodated sterically than the propyl group. No definitestructure can be assigned, however, in the absence of structural data.The only ruthenium-nBu2S0 complexes reported in the literature areRuX3(nBu2S0)3 where X= Cl and Br [117,118], and these were characterized byelemental analysis and infrared spectroscopy. The authors reported that the complexescontained both 0- and S-bonded sulfoxide ligands. No structural data were available ineither report.4.2.6 [RuC12(MePhS0)2]nThis title complex, isolated from the reaction of MePhS0 with the "ruthenium-blue" solutions as previously reported [112,196], analyzed well for the empiricalformula RuC12(MePhS0)2, and is considered to be a polymeric species. The complexwas submitted for mass spectroscopy (El and FAB) but no peaks other than those dueto the matrix were detected. Attempts to grow crystals of the compound have beenfruitless to date. The Signer method [139] was used in an effort to determine themolecular weight of the complex but the complex precipitated before the end of the144experiment.The solid state infrared spectrum of the complex isolated in this present workhas a strong absorption band at 1124 cm-1 (vs. 1047 cm-1 for the free ligand) whichis indicative of S-bonded MePhS0 (Section 3.6.2, p.70). The u for thepreviously reported complex [196] is slightly higher at 1130 cm* The solution state(CH2C12) infrared spectrum of the complex (not recorded previously), however, hasadditional bands at 1012 and 1045 cm-1 which are attributed to 0-bonded and freeMePhS0, respectively (Section 3.6.2). The complex isolated in this present work issoluble in CH2C12 but not in other common solvents, while that reported previouslywas only sparingly soluble in acetone and no NMR data were recorded [196].In the present work, the 1 H NMR was measured in CD2C12. The methyl regionof the spectrum resembles that of cis-RuC12(DMS0)4 [108]; overlapping multiplets inthe phenyl region (6 6.8 - 8.2 ppm) are observed which are attributed to the phenylsubstituent on the sulfoxide. The remaining resonances are all singlets due to themethyls and occur at S 2.66 (free MePhS0), 2.80 (0-bonded MePhS0), 3.20, 3.22,3.70 and 3.79 (S-bonded MePhS0) ppm. For comparison, the 1H NMR spectrum ofcis-RuC12(DMS0)4 in CDC13 [108,196] consists of six singlets in the same range butthese are slightly further upfield at S 2.60 (free DMSO), 2.73 (0-bonded DMSO), 3.33,3.42, 3.49 and 3.52 (S-bonded DMSO) ppm; the peak intensities in the spectra for bothcompounds are similar. The similarity of the assignments implies that the configurationof the polymeric complex in solution is similar to that of cis-RuC12(DMS0)4.Presumably, the polymer undergoes rearrangement in solution to give a mixture of145monomeric species which, by analogy to the 1H NMR spectrum of cis-RuC12(DMS0)4,consists of cis-RuC12(MePhS0)3(MePhSQ), RuC12(MePh50)3(CD2C12) and freeMePhS0. As noted above, the infrared spectrum of the complex in CH2C12 shows thepresence of 0-bonded MePhS0.The differences between the complex prepared earlier and during this presentwork can not be explained at the present time. The reaction conditions used to prepareboth complexes are the same, and in each case, the analytical values (C and H) are veryclose to the calculated ones. The complex was first prepared to evaluate its potential asa catalyst for homogenous asymmetric hydrogenation but such studies were curtailed byits lack of solubility [196]. Likewise, the poor solubility of the complex in waterprevented the study of this complex as a potential anti-cancer agent.4.2.7 RuCI3(Ph2S0)2 and mer-RuCl3(Ph2S0)2(Me0H)The reaction of Ph2S0 with the methanolic "ruthenium-blue" solutions (seeSection 2.4.1, p.45) resulted in the isolation of two closely related compounds. A fineyellow powder, which was collected and dried in vacuo, precipitated following theaddition of ether to the final reaction solution. Dark orange crystals were subsequentlydeposited from the remaining filtrate and were initially assumed to be crystals of theyellow precipitate. The spectroscopic data for both products are essentially identicalexcept for the presence of methanol in the crystalline material which gives rise to theextra peaks in the IR and 1H NMR spectra (see below); the methanol is present as aligand (as determined crystallographically). The overall yield of complexes from the146reaction solution was about 75%, that of the yellow precipitate being approximatelythree times greater than that of the crystalline product. Both products are stable in airin the solid state but change colour slowly from yellow to green in CH2C12 solution.The yellow precipitate analyzed well for RuC13(Ph2S0)2 (C and H) althoughthe values determined for Cl are about 1% lower than the calculated values; this isthought to be due to incomplete combustion of the complex despite the use of addedcombustion agents. The chloride analysis was repeated using different methods but thevalues were consistently lower than expected.The isolation of a Ru(III) species using the "ruthenium-blue" solutions was againsurprising considering that the reaction solution was refluxed under H2, and the workupdone in Ar. A Ru(III) species was also isolated using the same procedure with nPr2S0(Section 4.2.2). In both cases, air was excluded from the system, and so oxidation ofthe metal is unlikely to be due to oxygen. Reduction of some sulfoxide to the thioetherin both cases is probably a likely explanation for the isolation of the resulting Ru(III)species. The mechanistic steps of the reduction process are unclear but evidence for thereduction of sulfoxides has been reported [157,188] (Section 3.10.3, p.124). Thereaction was repeated with subsequent exposure of the final reaction solution to air; thesolution changed from yellow to green but, as in the corresponding the Ru(III)/nPr2S0reaction, no complex could be isolated (Section 4.2.2). The presence of Ru(III)-Ru(II)species in the "ruthenium-blue" solutions (Section 2.4.1, p.45) may also havecontributed to the isolation of a Ru(III) species.The 1H NMR spectrum of the yellow precipitate in CD2C12 is generally147uninformative due to the paramagnetism of the Ru(III) species and consists of a broadhump in the phenyl region; sharp peaks are, however, observed which correspond tothose of the free ligand indicating that one of the sulfoxide ligands dissociates insolution.Two strong bands in the infrared spectrum of the yellow solid at 1085 and 1030cm-1 are attributed to vso of S- and 0-bonded Ph2S0, respectively. The band at 1030cm-1 disappears in the solution infrared spectrum and a new band appears at 1045 cm-1(free Ph2S0 in CH2C12) which is consistent with the dissociation of the 0-bondedPh2S0, as previously observed in the 1H NMR spectrum.The infrared spectrum of the crystals in the solid state again contains two strongbands at 1085 and 1030 cm-1, attributed to S- and 0-bonded Ph2S0, and a broad bandat 3420 cm-1 assigned to the -OH group of the coordinated methanol. The 1H NMRspectrum of the crystals in solution is essentially the same as that of the yellowprecipitate except that an additional peak at .5 3.32 ppm is observed which correspondsto the methyl group of methanol. The structure of the crystalline material wasdetermined by single X-ray crystallography and showed the presence of both S- and 0-bonded Ph2S0 as well as a molecule of coordinated methanol.4.2.8 The Crystal Structure of mer-RuC13(Ph2S0)(Ph2S0)(Me0H)Selected bond lengths and angles for RuC13(Ph2S0)2(Me0H) are tabulated inTable 4.3, and a stereoview of the structure showing 50% probability thermal ellipsoidsis reproduced in Figure 4.2.148C22^C15CalC20 C14Figure 4.2 A stereoview for RuC13(Ph250)(Ph2SQ)(MeQH) showing 50%probability thermal ellipsoids for the non-hydrogen atomsThe two Ph2S0 ligands (one S- and the other 0-bonded) are mutually trans, andthe chlorides occupy mer positions in the equatorial plane while the methanol occupiesthe fourth site. In addition, the proton of the hydroxyl group is hydrogen-bonded to the0 of the S-bonded Ph2S0. The molecule has approximate octahedral geometry at theRu centre; the trans angles range from 171.84(7) to 175.02(8)°, and the cis angles from85.93(9) to 94.84(9)°. The average cis methoxide 0-Ru-C1 angles (ay. 86.37°) aresmaller than the two cis Cl-Ru-Cl angles (ay. 93.47°), which indicates that the threechlorines are sterically more demanding than the coordinated methanol.The average bond length of the mutually trans Ru-Cl bonds (2.328 A) iscomparable to those found within other mer-RuC13(L)3 (L = sulfoxide or sulfide)149Table 4.3 Selected Bond Lengths and Angles for mer-RuC13(Ph2a0)(Ph2SD)(MeDH)Bond Lengths (A) Bond Angles (°)atom atom distance atom atom atom angleRu(1) C1(1) 2.3165(9) C1(1) Ru(1) C1(2) 172.03(4)Ru(1) C1(2) 2.339(1) C1(3) Ru(1) 0(3) 175.02(8)Ru(1) C1(3) 2.301(1) S(1) Ru(1) 0(2) 171.84(7)Ru(1) S(1) 2.2391(9) C1(1) Ru(1) 0(3) 86.82(9)5(1) 0(1) 1.486(2) C1(2) Ru(1) 0(3) 85.93(9)Ru(1) 0(2) 2.122(2) CI(1) Ru(1) C1(3) 94.84(4)S(2) 0(2) 1.529(2) C1(2) Ru(1) C1(3) 92.11(4)Ru(1) 0(3) 2.094(3) 0(3) H(1) 0(1) 153(7)0(3) H(1) 0.95(8)0(1) H(1) 1.79(7)S-bonded Ph2S0 0-bonded Ph2S0atom atom atom angle(°) atom atom atom^angle(°)0(1) S(1) C(1) 105.6(2) 0(2) S(2) C(13)^105.2(2)0(1) S(1) C(7) 106.4(2) 0(2) S(2) C(19)^103.3(2)C(1) S(1) C(7) 100.0(2) C(13) S(2) C(19)^98.5(2)Ru(1) S(1) 0(1) 109.4(1) Ru(1) 0(2) S(2)^119.6(1)Ru(1) S(1) C(1) 115.6(1)Ru(1) S(1) C(7) 118.6(1)150complexes reported in the literature and this work (2.33 - 2.35 A, see Table 4.2, p.137,for appropriate references). The Ru-Cl bond length trans to 0 is significantly shorter(2.301 A), and this is attributed to the weaker trans influence of 0. As expected, theRu(III)-C1 bond lengths are shorter than those found in Ru(11)/C1/sulfoxide complexeswhich are normally about 2.40-2.44 A (Table 4.2, p.137), and this is presumably dueto the smaller ionic radius of Ru(III) compared to that of Ru(II) [194].The Ru-S bond length in the complex is shorter (2.239 A) than those found inother Ru(III)/sulfoxide and sulfide complexes which are trans to S or Cl (in the range2.331 - 2.390 A, Table 4.2, p.137), again due to the weaker trans influence of 0 (vs.S or Cl). A similar situation is found within the Ru(II)/DMS0 systems where theshorter Ru-S bonds are those that are trans to 0 (e.g. 2.248 A in cis-RuC12(DMS0)4[107,124]), while those trans to Cl or S are longer (e.g. 2.277 A in cis-RuC12(DMS0)4[107,124] and 2.353 A in trans-RuC12(DMS0)4 [121,124], respectively). The Ru-0bond (trans to S) in RuCl3(Ph2S0)2(Me0H) is significantly longer (2.122(2) A) thanthat in mer-RuC13(DMS0)2(DMS0) which is trans to CI (2.077 A [157]) and isattributed to the greater trans influence of S vs. Cl.The SO bond length of the 0-bonded Ph2S0 (1.529(2) A) in the complex islonger than that found within free, crystalline Ph2S0 (1.47 A [152]) as expected for 0-bonded sulfoxides (Section 3.4, p.64). The corresponding SQ bond length found withinmer-RuC13(DMS0)3 (1.545(4) [172(b)]) is also slightly longer (than that in freeDMSO), while those within the protonated sulfoxides (DMSO, TMSO and nPr2S0, seeSection 4.2.2) are considerably longer (than in the free sulfoxides) due to the presence151of strong O-H interactions with the sulfoxides (ay. O-H distance is 1.22 A, Table 4.2).The SO bond distance in the S-bonded Ph2S0, however, is longer than expected(1.486(2) A) being somewhat greater than that in the free ligand (1.47 A [152]); thisis presumably because the bond is not representative of a "pure" S-bonded SO bond dueto the interaction between the 0 of the S-bonded Ph2S0 and the hydroxyl proton ofmethanol. The SO bond distance is thus probably a compromise between the opposingeffects of the two bonding modes; S-bonding decreases the SO bond length while 0-bonding increases it (Section 3.4, p.64). The O-H distance between the proton andsulfoxide is 1.79(7) A and that between the proton and methanol is 0.95(8) A; the 0-H-0 angle is 153(7)°. The combined 0-0 distance (2.64 A) is less than the sum of thevan der Waals radii of the two oxygens, indicating that the interaction is an appreciableone [192]. Examples of other SO bond lengths that fall within the realm of "pure" 5-bonded and 0-bonded SO bond lengths due to simultaneous coordination through S and0 can also be found in [RuBr3(TMS0)4Li]2, reported in this present work (Section3.9.5, p.111) and in refs. 171(b) and (c).4.3 Chelating Sulfoxide Complexes of RutheniumPrevious workers in this group have used cis-RuC12(DMS0)4 and cis-RuC12(TMS0)4 as precursors to nitroimidazole complexes of Ru [49,50]; theconfigurations of the resulting RuC12(sulfoxide)2(L)2 (sulfoxide = DMSO or TMSO,L = nitroimidazole) complexes were not easily resolved because of the number ofpossible isomers within these 2,2,2 complexes. The range of sulfoxides was thus152extended in the present work to include chelating sulfoxides in order to reduce thenumber of possible isomers, and the complexes reported here are the first examples ofstructurally characterized chelating sulfoxide complexes of Run.Ruthenium complexes with bidentate sulfoxide ligands (chiral and non chiral) areknown in the literature and were evaluated as potential catalysts for homogenoushydrogenations although no structural data were reported [109-112]. Reports on thespectral properties of other chelating sulfoxide complexes of other transition metals havealso appeared in the literature [197,198]. Complexes of the first row transitionmetals (Mn - Zn) and Cd were reported to have the general formula[M(sulfoxide)3]2±[C104]2- where sulfoxide = the entirely 0-bonded bidentatesulfoxides (RS(0)(CH2)nS(0)R, for R = Me, Et and n = 2, R = Me and n = 3, R= Me and n = 4 [197]); complexes of Pd2+ and Pt2+ were square planar of the typeM(Me5(0)(CH2)2S(0)Me)C12 [197(a)] and contained, in contrast, only one exclusivelyS-bonded chelating sulfoxide ligand. No structural data were reported and formulationof the complexes was based on elemental analysis and infrared data [197,198].The structures of the chelating sulfoxide complexes of ruthenium isolated duringthis present work are considerably less varied than those of the monodentate sulfoxidesand have the general formula RuC12(sulfoxide)2 with solely S-bonded sulfoxides. Allthe compounds were structurally characterized and are generally similar to one another.The complexes are air-stable but decompose slowly (over days) in water presumably vialigand substitution reactions; a black solid was eventually deposited from the solutions.Details of their in vitro behaviour in Chinese Hamster Ovary cells are presented in153Chapter Trans-RuC12(BMSE)2The reaction of BMSE (MeS(0)(CH2)2S(0)Me) with the "ruthenium-blue"solution (see Section 2.4.1, p.45) yielded a yellow complex which analyzed well for thedichloro complex. No purification steps were required, and the complex was obtainedin good yield (80%). Attempts to isolate more of the complex from the remainingfiltrate were unsuccessful.The SO stretching frequency of free BMSE in the infrared spectrum occurs at1018 cm-1 and increases to 1109 cm-1 upon coordination of the sulfoxide to Ru,consistent with S-bonded sulfoxides. The 1H NMR spectrum in D20 of the free ligandconsists of a singlet at (5 2.68 ppm (CH3) and multiplets at (5 3.15 ppm (-CH2CH2-)both of which are shifted downfield to (5 3.39 and 3.95 ppm, respectively, uponcoordination through S as expected (Section 3.4, p.64). The complex (prior to thestructural analysis) was assigned a trans-configuration on the basis of the one 1H NMRsinglet observed for the methyls, as inequivalent methyls would be observed in a cisconfiguration. No free sulfoxide was observed indicating that the sulfoxides remainedcoordinated in aqueous solution. The molar conductivity of the complex in water was60 ohm-1 mol-1 cm2 (this initial value remained constant for at least 36 h), indicatingthat some dissociation occurs in solution which is probably due to the chlorides beingreplaced by water. The conductivity and NMR data suggest that the aqueous solutionof the complex contains a rapidly equilibrating mixture of a dichloro and aquo-chloro154species.Crystals of the complex were grown from a saturated solution of the complexin hot water, and the structure determined; details are discussed in Section 4.3.4.Selected bond lengths and angles are tabulated in Table 4.4, and full experimentaldetails (not including structure factor tables) are found in Appendix D. The structureof the complex is reproduced in Figure 4.3.Figure 4.3 A stereoview of trans-RuC12(BMSE)2 showing 50% probability thermalellipsoids for the non-hydrogen atoms4.3.2 Cis-Ru Cl2(BESE)2The title compound containing EtS(0)(CH2)2S(0)Et was synthesized via the155Figure 4.4 A stereoview of cis-RuC12(BESE)2 showing 50% probability thermalellipsoids for the non-hydrogen atoms"ruthenium-blue" solutions (Section 2.4.1, p.45). The filtrate was left to cool to roomtemperature, and crystals suitable for X-ray crystallography were formed within twohours. The structure of the complex is shown in Figure 4.4, and selected bond lengthsand angles are found in Table 4.4; the structural details are discussed in Section 4.3.4.Full experimental details are given in Appendix D although structure factor tables arenot included.The SO infrared stretching frequency for the free ligand is increased uponcoordination (1015 to 1101 cm-1) indicating that the sulfoxides are S-bonded. The 1HNMR of the complex in D20 is more complicated than that observed for trans-RuC12(BMSE)2 and some of the assignments are somewhat tentative. Two triplets,156assigned to the methyl groups, are observed at 5 1.36 and 1.55 ppm, shifted downfieldfrom the free ligand position at (5 1.35 ppm. The presence of two peaks indicates thepresence of two inequivalent methyls and, on this basis, the complex was initiallyassigned a cis-configuration which was later confirmed by the structure.The remaining resonances in the 1H NMR spectrum consist of a complex seriesof overlapping multiplets in the region 5 3.2 to 4.2 ppm due to the various methyleneprotons of the two inequivalent ligands. While it is not possible to differentiate betweenthe peaks due to the each ligand, selective decoupling experiments and a 2D COSYexperiment were useful in determining if the peaks were due to the backbonemethylenes or those in the ethyl chain. The triplet of doublets centred at .5 3.30 ppm isdue to two of the diastereomeric methylenes within the backbone of one ligand (2 x Haor Hb), while the multiplet at (5 3.45 ppm (which is simplified when the triplets aredecoupled) is assigned to the methylenes of the ethyl group.The multiplet centred at (3 3.67 ppm is simplified by decoupling of the methylsand consists of two overlapping multiplets (5 3.63 and 3.70 ppm) which are due to twobackbone methylene protons and four protons of an ethyl group, respectively. Similarly,the two overlapping multiplets, centred at (5 3.90 and 3.95 ppm, correspond to twoprotons each from the backbone methylenes of a ligand and the methylene of an ethylgroup, respectively. The approximate doublet of triplets centred at 5 4.09 ppm isassigned to 2 protons from the backbone of a ligand.The molar conductivity of the compound in water was 33.9 ohm-1 mol-1 cm2which indicates that some dissociation (presumably the chlorides) occurs in solution. No157free sulfoxides were detected in solution in the 1H NMR spectrum. The cellaccumulation characteristics of the compound in Chinese Hamster Ovary cells were alsostudied, and these findings discussed in Chapter Trans-RuC12(BPSE)2The title complex containing (nPrS(0)(CH2)2S(0)nPr) was synthesized using the"ruthenium-blue" solutions (described in Section 2.4.1, p.45). Crystals suitable for X-ray crystallography were grown in a saturated solution of Me0H/water (10:1 v/v).Selected bond lengths and angles are tabulated in Table 4.4 and full experimental detailsFigure 4.5 A stereoview of trans-RuC12(BPSE)2 showing 50% probability thermalellipsoids for the non-hydrogen atomscan be found in Appendix D. The structure of the complex is reproduced in Figure 4.5,158and the structural details are discussed in Section 4.3.4 together with those of trans-RuC12(BMSE)2 and cis-RuC12(BESE)2.The infrared data for trans-RuC12(BPSE)2 indicate that the SO stretchingfrequency for free BPSE is shifted to a higher frequency upon coordination (1010 to1109 cm-1) indicating that S-bonded sulfoxides are present within the complex.The 1H NMR spectrum of the free ligand in CD2C12 is quite simple and consistsof a triplet at 6 1.10 ppm (methyls) and multiplets at 6 1.85, 2.80, and 3.2 ppm whichcorrespond to the fl- and a-protons of the propyl chain and the diastereomeric protonsof the carbon backbone methylenes, respectively. The 1H NMR spectrum of complexin CD2C12 shows that the resonances of the free ligand are generally shifted downfieldand that some of the protons become more inequivalent as expected for S-bondedsulfoxides (Section 3.4, p.64).The triplet at 6 1.10 ppm in the 1H NMR spectra of the complex is assigned toequivalent methyls which is indicative of a trans configuration (later confirmed by thecrystal structure). The remainder of the proton spectrum consists of two sets of twomultiplets centred at (5 2.00 and 3.50 ppm, respectively, with an integration ratio of 2:1.The multiplets at 6 3.50 ppm are assigned to the two sets of methylenes (backbone andpropyl chain) adjacent to the S atom. The remaining set of multiplets centred at 6 2.00ppm is due to the /3-protons in the propyl chain which, of some interest, becomeinequivalent upon coordination to the metal. The 1H NMR spectrum of the complex wasalso run in D20, and no free sulfoxides were detected. The inequivalence of the a-protons (backbone carbons and propyl chain) increases as expected for S-bonded159sulfoxides (Section 3.6.1, p.68), but it is not apparent why the (3-protons should becomeinequivalent when the sulfoxide is coordinated.4.3.4 The Crystal Structures of the RuCl2[RS(0)(CH2)25(0)% complexes, R =Me, Et and "PrSelected data for the three complexes are tabulated in Table 4.4 for comparison,and the details discussed together because the three structures are very similar. All threecomplexes are essentially octahedral with trans angles ranging from 173 to 184° and cisangles ranging from 87° to 93° (see Appendix D). Each molecular structure shows twobidentate sulfoxides coordinated exclusively through S; the BMSE and BPSE complexesare trans while the BESE one is cis.The Ru-C1 bond lengths within the cis complex are slightly longer than thosewithin the trans complexes (Table 4.4) due to the stronger trans influence of S, but aretypical of those found in other Ru(II)-C1 complexes (e.g. 2.42 A in the Ru(II)/C1/DMS0systems, Table 3.5, p.84). The same pattern is seen with the Ru-S distances (Table 4.4),where the mutually trans bond distances in the cis-complex are longer than those transto Cl. These bond distances are again similar to those found in other Ru(II) systems(e.g. the DMSO and TMSO systems, Table 3.5 and Section 3.9.1(a), p.94).The SO bond lengths of the three complexes fall in the range 1.45 -1.48 A andare comparable to those found in S-bonded DMSO and TMSO (Table 3.5 andTable 3.6, p.86). In accordance with data for other S-bonded sulfoxides, these bonddistances are probably shorter than those in the free ligand; no structural data for the160Table 4.4 Selected Bond Lengths and Angles for trans-RuC12(BMSE)2, cis-RuC12(BESE)2 and trans-RuC12(BPSE)2Bond (A or °) trans-RuC12(BMSE)2 cis-RuC12(BESE)2 trans-RuC12(BPSE)2Ru-Cl 2.40a 2.44b 2.41aRu-S 2.31b 2.30b 2.31b2.27aS-0 1.47 1.48 1.45C-S 1.79 1.80 1.80C1(1)-H(43)d 2.356C1(4)-H(44)d 2.408Ru-S-0 119.3 118.41 119.3C-S-0 108 108 107.1C-S-C 101 102 101S-C-Ce 109.5 109.5 108.6Ref. twc twc twca trans to Cl.b trans to S.C tw = this work.d Found in trans-RuC12(BMSE)2 only.e Backbone carbons.free ligands have been found in the literature but by extrapolation of the present data,the SO bond distances within the free ligands are probably similar to that found in freeDMSO (Table 3.1, p.61) and TMSO [153] and are likely to be about 1.5 - 1.6 A.The C-S bond lengths and bond angles for the ligands within the three complexes161are similar to those found within free sulfoxides (e.g. DMSO, Table 3.1, Ph2S0 [152]and TMSO [153]), indicating that the structures of the free sulfoxides are essentiallyunchanged by coordination. The structures of the coordinated ligand can probably beused as approximations for the structures of the free ligand. The average S-C-C bondangle (109°) found within the coordinated ligands is that of tetrahedral carbon indicatingagain that the geometry of the ligands is unchanged upon coordination. In addition, theinternal bond angles are typical of those found within five-membered rings such ascyclopentane (108°) [199]Of some interest, the unit cell for trans-RuC12(BMSE)2 contains a watermolecule hydrogen-bonded to two chlorides from two different molecules of thecomplex. The average H-Cl distance is 2.38 A, which is 0.87 A shorter than the sumof the van der Waals radii of Cl and 0 (3.25 A) and is indicative of strong hydrogenbonding [192]. Previous crystal data reported for other Cl..0-H systems do not meetthe requirements for strong hydrogen bonding [200].4.3.5 Cis-RuC12(BMSP)2The title complex containing MeS(0)(CH2)3S(0)Me was again isolated from thereaction of the ligand with the "ruthenium-blue" solutions as described in Section 2.4.1,p.45). As with the other chelating sulfoxide complexes, the compound was isolated inhigh yield and purity. Crystals suitable for X-ray crystallography studies were obtainedfrom saturated solutions of the complex in ethanol. Selected data for the structure of thecomplex are tabulated in Table 4.5, and a stereoview of the complex is shown in162Figure 4.6; the details of the structure are discussed in Section 4.3.6.In the free sulfoxide ligand, the infrared stretching frequency for the SO moietyis seen at 1050 cm4; the increase in vso to 1085cm-1 found in the complex indicatesthe presence of S-bonded sulfoxide, as previously discussed (Section 3.4, p.64).Figure 4.6 A stereoview of cis-RuC12(BMSP)2 showing 50% probability thermalellipsoids for the non-hydrogen atomsThe ' H NMR spectrum of the free ligand in CD2C12 consists of one singlet at6 2.6 ppm (CH3), and two multiplets at (5 2.37 (-CH2-) and 2.89 ppm (S-CH2) with anintegration value of 1:2. The proton spectrum of the complex, however, has two singletsat 6 3.38 and 3.45 ppm which are assigned to inequivalent methyl groups, indicative ofa cis configuration (confirmed later by the structure). In addition, the methylene protonsbecome more inequivalent upon coordination. The original multiplet at 6 2.37 ppm splits163into two broad multiplets centred at 6 2.56 ppm; similarly, the multiplet at 6 2.89 ppmis split into two sets of approximate doublets of triplets, and shifted downfield to 6 3.7and 4.0, respectively.4.3.6 The Crystal Structure of cis-RuC12(BNISP)2The structure of the cis-RuC12(BMSP)2 is similar to those of the other bis-chelate complexes discussed in Section 4.3.4. The molecule has slightly distortedoctahedral geometry at the Ru with trans angles that range from 174 to 178° and cisangles that range from 83 to 99° (see Appendix D).Table 4.5 Selected Bond Lengths and Angles for cis-RuC12(BMSP)2Bond Lengths (A)^ Bond Angles (°)distance atom atom^atom angle2.43 Ru S^0 115.42.35a C S^0 106.12.27bC S^C 1001.48S C^C 114.91.79C C^C 1 13.3atom atomRu^ClRu SS^0C^Satrans to S.btrans to Cl.The selected bond lengths and angles tabulated in Table 4.5 are similar to thosefound for the other chelating sulfoxide complexes (Table 4.4). The average Ru-Cl bondlength is 2.43 A which is typical for that found in other Ru(II)-sulfoxide systems (e.g.164the DMSO and TMSO systems, Sections 3.8.1(a) (p.76) and 3.9.1(a) (p.94)). Theaverage SO bond length is 1.47 A and, again, is comparable to those within the otherchelating sulfoxides complexes (Table 4.4) and those for S-bonded DMSO and TMSO(Sections 3.8.1(a), 3.8.2(a) and 3.9.1(a), pages 76, 79 & 94, respectively).The bond angles tabulated for the coordinated ligand in Table 4.5 are typical ofthose found in other S-bonded systems indicating that the geometry of the free ligandis retained even upon coordination (see Sections 3.4 (p.64) and 4.3.4). No structuraldata for the BMSP sulfoxide have been found in the literature but the data presented forthe ligand within the complex can probably be used as an approximation for thestructure of the free ligand.The average S-C-C (114.9°) and C-C-C (113.3°) bond angles found within thecoordinated sulfoxide ligand are smaller than those expected for planar six-memberedrings (120° [199]) due to puckering of the ring. The deviation from typical tetrahedralangles is due to the ring strain effects. As expected, these angles are larger than thosefound within the five-membered rings formed with the RS(0)(CH2)2S(0)R sulfoxides.165Chapter 5: The Assessment of Selected Biological Properties ofRuthenium Sulfoxide Complexes5.1 IntroductionA preliminary investigation into the in vitro activity of the ruthenium sulfoxidecomplexes was initiated as part of the project. Reports on the anti-tumour activity of cis-and trans-RuC12(DMS0)4 [124,201] and other Ru-DMS0 compounds [202] hadappeared in the literature, and an inquiry into the possible in vitro activity of thecomplexes synthesized during the course of this work (Chapters 3 and 4) seemed to bethe next logical step. The ability of the complexes to traverse the cell membrane and tobind to DNA were two fundamental considerations as DNA is considered to be thetarget for cell kill. The toxicity of the complexes was also of interest (especially inaerobic vs. hypoxic conditions) if the complexes did accumulate in the cell and bind toDNA. The toxicity and accumulation characteristics (in aerobic and hypoxic conditions)of the complexes in Chinese Hamster Ovary (CHO) cells were thus studied. Preliminaryinvestigations into the interaction of the Ru-sulfoxide complexes with DNA were alsocarried out using a damaged DNA precipitation assay [203]. The work presented inthis chapter indicates some interesting prospects for further investigation (Section 6.6,p.195) although the results of these tests are not comprehensive and should not be over-interpreted.1665.2 The Ruthenium Sulfoxide Complexes StudiedSeven of the complexes discussed in Chapters 3 and 4 were selected for studybecause they were structurally characterized and water-soluble. The complexes areTable 5.1 Ru Sulfoxide Complexes Studied In VitroCode Complex mMa Sectionb1 cis-RuC12(DMS0)4 1.00 3.8.1(a)2 trans-RuC12(DMS0)4 1.00 3.8.2(a)3 cis-RuC12(TMS0)4 1.00 3.9.1(a)4 trans-RuC12(BMSE)2 1.00 4.3.15 cis-RuC12(BESE)2 0.50 4.3.26 trans-RuC12(BPSE)2 0.50 4.3.37 cis-RuC12(BMSP)2 1.00 4.3.5a Concentration of the complex in aqueous buffered solutions used for all biologicaltests, unless stated otherwise.b Details on the complexes can be found in the quoted sections.summarized in Table 5.1 with their respective code numbers and the concentrations atwhich they were studied. The lower solubility of complexes 5 and 6 prevented the useof concentrations much higher than about 0.5 mM.1675.3 The Biological Activity of Ruthenium Sulfoxides in CHO CellsThe results and implications of the various assays carried out with thesecomplexes are presented first in Sections 5.3.1 - 5.4, and the materials and methodsdescribed in the second half of the chapter beginning at Section M5.5, p.181 (the"Methods and Materials" Sections are given the preface M for easier identification). Insome cases, where the details detract from the main text, a condensed account of thetechnique (or results) is presented within the text, and the reader is referred to theappropriate Appendix for complete details.5.3.1 Whole Cell Accumulation under Air or N2The purpose of such studies was to quantify the amount of complex presentwithin the cell or cell nuclei after a specified period of time under different conditions.Cells were incubated with solutions of the complexes (Section M5.5.2, p.182), and theamount of complex present in the cell was determined using atomic absorptionspectroscopy (AAS) to analyze for the amount of Ru present (Section M5.5.4, p.184).5.3.2 Complex Accumulation in Cells after Four Hours Under Air or N2The aim of the experiment was to look for selective accumulation (if any) of thecomplexes in air and under hypoxic conditions. The CHO cells were incubated in thedrug solution for 4 h, under oxic and hypoxic conditions (Section M5.5.2, p.182), anddigested with HNO3 to form a homogeneous "cell solution" prior to analysis forruthenium using AAS (see M5.5.4, p.184). The results indicate the gross amount of168complex (expressed as ng Ru/106 cells) present in the whole cell and not the relativeamounts present within the different cellular components (e.g. membranes, nuclei andproteins).The results are plotted in Figure 5.1 and indicate that the complexes doaccumulate in CHO cells and to varying degrees, but that there is no significantdifference between accumulation under air or N2. Of considerable interest, the greatestdegree of accumulation (in oxic conditions) is seen in cell solutions of the three transcomplexes, RuCl2(DMS0)4 (2), RuC12(BMSE)2 (4) and RuC12(BPSE)2 (6), withaccumulations averaging around 85, 92 and 175 ng Ru/106 cells, respectively.Accumulation of the cis complexes by the cells after 4 h is much lower and generallyfalls in the 6 - 40 ng Ru/106 cells range. An exception is the higher accumulation ofcis-RuC12(TMS0)4 (3) which may be due to changes in the pH of the solution (seeSection 5.3.3).5.3.3 Accumulation Profiles of Selected Ruthenium SulfoxidesThe "pattern" of accumulation of the complexes over time was studied; thusCHO cells were incubated in solutions of the complexes for 6 h under air or N2(Section M5.5.2, p.182), and approximately 2 x 106 cells were removed every hour andanalyzed for Ru by AAS. The amount of ruthenium found within the cells (ng Ru/106cells) was then plotted vs. time, and an accumulation profile for each complexgenerated. Two representative plots are shown in Figures 5.2 and 5.3, and theremainder are found in Appendix B. The cells were incubated in solutions that were169250• Oxic uptake- • Hypoxic uptake200 —-.0ov-I.......150 —cog „,g 71;r4 u-100 —aencr4'\s,^Inx■i^ aNOa 030^,\-50 —■1301..44, 91^2^3^4^5^6^7CompoundFigure 5.1 Whole cell accumulation of Ru-sulfoxides in CHO cells at 4 h; theamounts of Ru is expressed as ng/105 cells (+ 10%)1 = cis-RuC12(DMS0)4, 2 = trans-RuC12(DMS0)4, 3 = cis-RuC12(TMS0)4, 4 =trans-RuC12(BMSE)4, 5 = cis-RuC12(BESE)2, 6 = trans-RuC12(BPSE)2, 7 = cis-RuC12(BMSP)2.a accumulation may be due to pH effects, see Section buffered (using 20 mM N-2-hydroxyethylpiperazine-N'-2-ethane sulfonic acid(HEPES), pH 7.4), or unbuffered in order to examine the effect of pH changes due tonormal cell activity under air and N2 on accumulation of the complexes. The pH of cellsolutions, incubated over 6 hours can vary (± 0.25), especially in hypoxic conditions,and the pH change may effect the accumulation of the complexes.5.3.3(a) Common Features in the Accumulation ProfilesThe accumulation profiles for all seven complexes share some common features:(a) Accumulation of the complexes in both the buffered and non-buffered solutions wasgenerally similar except for complex 3 (cis-RuC12(TMS0)4). The accumulation of 3appears to be pH-dependent in hypoxic conditions; in the absence of buffer,accumulation increases dramatically and almost reaches the 200 ng mark by the sixthhour. (b) No significant differences in accumulation in air or N2 were observed duringthe course of the 6 h, corresponding to the results obtained in the 4 h accumulationexperiment (Section 5.3.2). (c) The rate of accumulation is fastest in the first hour, thengenerally slows down over the next 4 h.5.3.3(b) Individual Features in the Accumulation ProfilesWhile the accumulation profiles share some characteristics (see above), severalbroad distinctions may be made and, in general, the profiles can be divided into twotypes. Complexes 2 (trans-RuC12(DM_SO)4), 4 (trans-RuC12(BMSE)2) and 5 (cis-RuC12(BESE)2) have accumulation profiles which are generally linear and increase171—a— AirHi— Hypoxic--6— Air, +HEPES--a--- Hypoxlc, +HEPESsteadily with time (see for example, Figure 5.2) although complex 4 appears to reachthe beginning of a plateau region in the last hour. In contrast, the accumulation profilesof complexes 1 (cis-RuC12(DMS0)4), 3 (cis-RuC12(TMS.0)4), 6 (trans-RuC12(BPSE)2and 7 (cis-RuC12(BMSP)2) generally reach a plateau area after the third hour (see forexample, Figure 5.3).Figure 5.2 Accumulation of cis-RuC12(BESE)2 (5) at 0.50mM in CHO cellsThe linear profiles observed for the accumulation of complexes 2, 4 and 5 implythat accumulation of the complexes has not yet reached an equilibrium (accumulation= removal of the complex) over the 6 h period, or that the complex is being bound172-0—Air—0-- Hypoxic—,:,-- Air, +HEPES—e— Hypoxic, +HEPESFigure 5.3 Accumulation of trans-RuC12(BPSE)2 (6) at0.50 mM in CHO cellsirreversibly to some cellular component (e.g. proteins, DNA, or other cellularstructures) and is not being removed from the cell. The plateau regions found in theaccumulation profiles of the other complexes (1, 3, 6 and 7), however, indicate thataccumulation reaches a saturation point where presumably the rate of accumulation isequal to the rate of removal of the complex.The reasons suggested for the two types of profiles observed within the variouscomplexes are highly speculative but may be due to different binding kinetics within thevarious complexes. Of some interest, accumulation of complex 3 (cis-RuC12(TMS0)4)173increases dramatically past the fourth hour in the non-buffered, hypoxic solutions.Presumably, the combination of the hypoxic conditions and lack of buffering stressesthe cells to the point where processes responsible for the removal of extracelluarmaterial are inhibited. Accumulation of complex 3 at this point is thus possibly dictatedby passive diffusion processes.5.3.4 Accumulation of Ru in Cell NucleiThe purpose of this experiment was to examine whether the complexes penetratethe cell membranes and the nuclei. The CHO cells were incubated in solutions of thecomplex, and the nuclei isolated by mechanical lysis as described in Section M5.5.5,p.185. Treatment of the cells in this manner ensures that a minimum amount of boundcomplex is dislodged from cell membranes; the use of chemical means to dissolve cellmembranes and proteins may release bound complex into the cell solution, and thecomplex may subsequently bind to the nuclei.The number of nuclei present in each sample was not determined, so theanalytical results can not be expressed in terms of the number of nuclei present.However, all nuclei samples analyzed positively for Ru indicating that the complexesdo traverse the nuclear membrane. Presumably the complex is present in the nucleus,either bound to DNA or other nuclear components.The cell membranes and cytoplasm obtained from the lysis of whole CHO cellsusing the Dounce homogenizer (described in Section M5.5.5, p.185) were retained andalso analyzed for the presence of Ru using AAS. The samples all analyzed positively174for Ru, although the relative proportions present in the different cell components (e.g.proteins, cellular structures, etc.) were not determined.5.3.5 The Interactions of Ru-Sulfoxide Complexes with DNAThe interaction of the complexes with DNA was examined using the two assaysdescribed in Sections M5.5.6 and M5.5.7, p. 186. The results indicate that the Ru-sulfoxide complexes bind to both cellular DNA and isolated DNA although the data donot provide information on the nature of the interaction between the complex and DNA.5.3.5(a) The Damaged DNA Precipitation AssayThe damaged DNA precipitation assay was first used to isolate proteins whichrecognized DNA damaged by exposure to X-rays [204]. The assay was then usedto examine the proteins that recognized DNA damaged by cisplatin; these proteins werepurified and identified as high mobility group (HMG) proteins [205]. The HMG5proteins [206] are a family of highly conserved proteins that are found in mosteukaryotic organisms [207]. The functions of the proteins have not been elucidateddefinitively but may play important roles in maintaining the structure of DNA, intranscription and in the binding of H1 histones to DNA [206(b)].In the context of this present work, interest in the proteins stems from reportsindicating that HMG1 and HMG2 bind specifically to DNA damaged by cisplatin5 HMG = "high mobility group" which refers to the behavior of the proteins ingel electrophoresis [206(a)].175[203(a),208] which is clinically active. The assay has been used to study the natureof the adducts formed between DNA and other Pt complexes [203(b) & (c)], and wasthen used to examine the interaction of Ru-sulfoxide complexes with DNA in thispresent work.The results indicate that the complexes all interact with DNA in some mannerand that this interaction is recognized by the HMG proteins. The intensity of the proteinband on the gel is related to the number of adducts on the DNA and the strength of theHMG binding to the adduct, and so can be used as a qualitative measure of the amountof complex present on the DNA. On this basis, the trans-complexes, RuC12(DMS0)4(2), RuC12(BMSE)2 (4) and RuC12(BPSE)2 (6), appear to bind more to DNA than thecis-complexes.5.3.5(b) Binding to DNA in Whole CellsThe results of the DNA binding assay (see Table 5.2) indicate that complexes5 - 7 (0.18, 0.10 and 0.11 ng Ru/mg DNA, respectively) do not bind strongly to DNAisolated from CHO cells, while the DNA from cells incubated with 1 - 4 has almost tentimes the amount of Ru (1.67, 1.20, 1.21 and 1.34 ng Ru/mg DNA, respectively). Theamount of complex 6 that is associated with DNA is surprisingly low in view of the factthat the complex accumulates the most in CHO cells (Section 5.3.2) and causes damagewhich is the most "recognized" by HMG proteins (Section 5.3.5(a)). The low levels ofRu could be due to removal of the complex during the isolation procedures whichconsist of various digestion steps and washes (Section M5.5.7, p.186).1765.3.6 The Toxicity of Ruthenium Sulfoxides in CHO CellsThe toxicity of the selected complexes in CHO cells was measured as platingefficiency (PE) vs. time; a representative plot is shown in Figure 5.4, and the remainderare found in Appendix C. The complexes showed no significant toxicity towards CHOcells at the concentrations tested (complexes 1 - 4 & 7, 1.0 mM; 5 & 6, 0.50 mM). Thetoxicity of trans-RuC12(BMSE)2 (4) at 3.0 mM was examined in a single experiment,but no toxicity was seen up to 4 h. Based on these results, these ruthenium-sulfoxidecomplexes do not appear to be toxic towards CHO cells (either in air or in N2) up to4 h at the concentrations studied.5.3.7 The Partition Coefficients of Ru-sulfoxide ComplexesThe partition coefficients (P) of the complexes were measured as described inSection M5.5.9, p.188, and are tabulated in Table 5.2. Partition coefficients forcomplexes 3 and 6 could not be measured due to problems with solubility in octanol-saturated water. The partition coefficients for complexes 2 and 4 (trans-RuC12(DMS0)4and -RuC12(BMSE)2) are low (P = 0.038 and 0.017, respectively) relative to those ofthe cis-complexes, RuC12(DMS0)4, RuC12(TMS0)4 and RuC12(BMSP)2 (P = 0.22,0.13 and 0.56, respectively).Of some interest, complexes 2 and 4, which have higher total accumulationlevels (see Section 5.3.2), have lower partition coefficients. This is perhaps anindication that some mechanism other than diffusion is responsible for accumulation ofthese two complexes in the cell. The partition coefficient also increases (0.13 to 0.56)177-6-Control air-6-Control hypoxic--o-7 air-ui--7 hypoxicFigure 5.4 The toxicity of cis-RuC12(BMSP)2 (7) at 1.0mM, PE vs. Timewith the addition of one methylene group to the backbone of the sulfoxide ligand(BMSE to BMSP) in complexes 5 and 7.5.4 The Implications of the Biological ResultsThe results of the various biological assays present a preliminary survey of thebiological activity of these complexes (Table 5.2). While there are insufficient data toexplain in any detail the in vitro behaviour of the complexes, the results do point theway for future avenues of study. The complexes accumulate in CHO cells and bind toDNA but are non-toxic at the concentrations used. Moreover, no significant differentialis observed in the response of CHO cells to these complexes whether under oxic or178Table 5.2 Summary of Biological Results From the Various AssaysCompounda,b Accumulation Partition DNA binding "HMG"(ng/106cells)c Coeff. ng Ru/mg DNA Assayecis-RuC12(DMS0)4 30 0.22 1.67 weak(1)trans-RuC12(DMS0)4 80 0.038 1.20 strong(2)cis-RuC12(TMS0)4 59 d 1.21 weak(3)trans-RuC12(BMSE)2 107 0.017 1.34 strong(4)cis-RuC12(BESE)2 6 0.13 0.18 medium(5)trans-RuC12(BPSE)2 202 d 0.10 strong(6)cis-RuC12(BMSP)2 17 0.56 0.11 weak(7)a In each case, Ru was detected in the cell nuclei, and the complex showed no celltoxicity at the concentrations used (1.0 mM for 1 -4 & 7; 0.50 mM for 5 & 6).b In all the AAS experiments, blanks were run and no significant amounts of Ru weredetected.c The values reported here are for accumulation in air (unbuffered) after 4 hincubation.d The partition coefficients could not be measured due to solubility problems (seeSection 5.3.7).e The terms "weak", "medium" and "strong" refer to the intensity of the stain on thegel which is a qualitative indication of complex-DNA binding.179hypoxic conditions.The most obvious feature that can be gleaned from the summarized data(Table 5.2) is that the highest degree of accumulation and binding to DNA (using thedamaged DNA precipitation assay) occurs with the trans complexes (2, 4 and 6).However, these complexes, despite being present within the cells in higherconcentrations, are non-toxic as found for the cis complexes. The reasons for the greateraccumulation of the trans complexes by CHO cells are not known, although theaccumulation is probably related to the interaction of the complex with DNA assuggested by the damaged DNA precipitation assay; presumably, the "stronger"interactions lead to greater accumulation of the complex in the cell.The results of the damaged DNA precipitation assay are of some interest; theinteraction of cisplatin (and analogues) with DNA was studied using this assay [203(b)& (c)], and the results to date indicate that the HMG proteins only recognize damageincurred by the cis isomers [209]. The results of the assay in the thesis workindicate that the HMG proteins recognize interactions between Ru-sulfoxides complexesand double-stranded DNA but, in contrast to the Pt work, interactions with the trans-Rucomplexes are the strongest. This implies that the interactions of the Ru-sulfoxidecomplexes with DNA may be similar to those between cisplatin and DNA or that theprotein recognizes other types of adducts or conformational changes in the double helix.The results of the various assays, taken as a whole, suggest strongly that theseRu-sulfoxide complexes have considerable potential as "carriers" to targetradiosensitizers onto DNA. Ideally, the non-toxic, accumulation and DNA binding180characteristics of the complexes would be retained with the addition of a nitroimidazoleligand to act as the radiosensitizer. Some preliminary attempts to synthesize Ru-sulfoxide-nitroimidazole complexes using the chelating sulfoxide complexes were madein the later part of this present work but the mixtures obtained could not be purified(Appendix E).Reports on the use of cis-RuC12(DMS0)4 and cis-RuC12(TMS0)4 as precursorstowards Ru-sulfoxide-nitroimidazole radiosensitizers appeared in earlier studies from thisgroup [49,50]. The results from this present thesis work indicate that the use of thetrans-Ru complexes as precursors (rather than cis complexes) to nitroimidazole-containing Ru-sulfoxide compounds may be more effective due to the higher levels ofaccumulation and DNA binding in the cell.M5.5 MethodologyThe experimental details are presented briefly in Sections M5.5.1 - M5.5.8;preparations of the reagents and solutions used are described fully in Appendix A. Theresults of each assay and the implications of the data were previously discussed inSections 5.3 - 5.4.M5.5.1 Cell Culture ProceduresThe cells used in the in vitro experiments were obtained from a Chinese HamsterOvary (CHO) cell line, chosen for its rapid growth cycle and high plating efficiency.The cells were routinely grown in spinner culture flasks in a +/ + medium (see181Appendix A), and the cell solutions were maintained at 37°C in a Associated BiomedicSystems "Incu-cover" incubator under an atmosphere of 95% air/5% CO2 (CanadianLiquid Air Co., Ltd.). Spinner flasks were changed twice a week, and 1 x 105 cellswere plated in T-75 flasks (Falcon) once a week as backups in the event that the spinnerculture was contaminated.The cell cultures were diluted daily to a cell concentration of about 1 x 105cells/mL to maintain an exponential growth phase cell population (doubling time wasabout 13-14 h); higher cell concentrations were prepared if a larger number of cells wasrequired the following day. The cell concentration (cells/mL) was determined using a"Coulter Cell Counter" from Coulter Electronics Inc., Hialech, Florida.M5.5.2 Cell Incubation ProceduresThe required number of cells was harvested from the culture solution using acentrifuge (Sorvall RC-3, 600 RPM at 4°C for 7 min). The cells were then resuspendedin a +/- medium and added to solutions of the complexes previously made up in thesame media. The incubation conditions and sampling frequencies were varied dependingon the experiment being performed (see below).The cells were incubated with solutions of the complexes (typically volumes of20 - 50 mL depending on the experiment) at a cell concentration of about 3.0 - 3.7 x105 cells/mL in standard Erlenmeyer flasks fitted with a modified rubber stopperdesigned to introduce a flow of gas (through a syringe needle) and easy sampling (seeFigure 5.5). The solutions were maintained at 37.4°C in a Labline Instruments "Orbit182Shaker Bath" which is a modified water-bath designed to agitate the flasks continuouslybut gently. All incubations were performed in a warm room with the temperaturemaintained at 37°C.Figure 5.5 Diagram of the modified Erlenmeyerflask used for the accumulation and toxicityexperimentsHypoxic conditions were emulated by passing oxygen-free N2 (Linde SpecialtyGas, Union Carbide) over the cell solution for an hour prior to the introduction of thecells and during the experiment. Filtered air was passed over the non-hypoxic solutionsto prevent the build up of CO2 due to cellular respiration. Both gas flows werehumidified in a glass bubbler filled with sterile water maintained at 37°C.All flasks and humidifiers were sterilized in a BBMC Century 21 LaboratorySterilizer, while media and test solutions were sterilized by filtration through a Nalgene0.22 Am filter unit, prior to use in toxicity experiments.183M5.5.3 Cell Accumulation StudiesIn a typical experiment, CHO cells were incubated in a test solution for aspecific period of time; approximately 2 x 106 cells were then removed from thesolution, pelleted by centrifuge, and the supernatant discarded. The cells were washedtwice with phosphate buffer saline (PBS, 10 mL at 0°C) to remove unbound complex.The cells were then resuspended in PBS (4.5 mL); the cell concentration wasdetermined (by adding 200 AL of the cell suspension into 19.8 mL PBS), and theremaining cell solution (4 mL) transferred into polypropylene tubes. The cells werepelleted, the supernatant removed by suction, and the cell pellet dried overnight byevaporation.Concentrated HNO3 (100 pL) was then added to the cell pellet, and the acidmixture agitated continuously at 37°C overnight to enhance digestion of the cell pellet.Doubled distilled water (500 gL) was then added to the digested cell solutions, and themixtures analyzed for Ru content using AAS, following calibration using Ru standardssupplied by Sigma. The analytical results were first calculated as ng/mL of Ru, thenexpressed as ng Ru/106 cells for accumulation results.M5.5.4 Atomic Absorption SpectroscopyA Varian "SpectrAA 300" atomic absorption spectrometer, controlled by aCompaq Deskpro 386s computer, was used to analyze for the presence of Ru in thecellular samples. The parameters for the instrument and furnace are tabulated inAppendix A; preparation of the samples is described in Section M5.5.3. A Ru hollow184cathode lamp (Varian) was used as the source, and samples were dried, ashed andatomized in graphite tube furnaces (Varian). Corrections for background absorptionwere done using a technique, developed by Varian, based on the Zeeman effect.M5.5.5 The Isolation of Nuclei from Whole CHO CellsSome CHO cells were incubated in test solutions for 4 h and their nuclei isolatedand analyzed for the presence of Ru to determine if the complexes penetrated thenuclear membrane. The procedure used for isolating the nuclei was a modified versionof that used for the isolation of HMG proteins [203(c)] (see also Appendix A).Approximately 6 x 106 cells were removed from solutions of the complex andwere lysed mechanically in a Dounce homogenizer (B type pestle) after two washingsin PBS (10 ml, 0°C) and one wash in a buffer solution (1 mL) consisting of 10 mMHEPES (pH 7.9), 1.5 mM MgC12, 10 mM KC1 and 0.5 mM dithiothreitol (DTI). TheDounce homogenizer consists of a glass tube with a precision fitted Teflon plunger. Asolution of the cells (1 mL) in the buffer solution used in the final wash was transferredto the homogenizer and given fifteen strokes with the plunger. The cell membranes weresheared by the motion of the plunger, and the cell membranes ruptured releasing thenuclei and cell cytoplasm. The cell solution was then checked for the presence of wholenuclei under a microscope, and the nuclei spun down by centrifuge (10 000 G, 20 min).The supernatant which consists of the cell cytoplasm and buffer solution wasretained and analyzed for the presence of Ru using AAS. The nuclei were pelletedfurther using a high speed ultracentrifuge (20 000 RPM, 4°C, for 30 minutes); any185resulting supernatant from this step was removed, and the nuclei pellet dried overnightby evaporation. Concentrated HNO3 (100 AL) was then added to the pellet, and the acidsolution agitated at 37°C overnight to digest the pelleted nuclei. Double distilled water(500 AL) was then added to the acid-nuclei solution prior to analysis for Ru by AAS.M5.5.6 An Outline of the Damaged DNA Precipitation AssayThe assay is described briefly below, and full experimental details are found inAppendix A. Calf thymus double stranded-DNA bound to a cellulose bead (Sigma) wasincubated (24 h at 37°C) in PBS solutions of the various complexes (for concentrations,see Table 5.1, p.167) and washed extensively following the incubation period. TheHMG proteins were isolated from V79 cells as described previously [203(c)] (see alsoAppendix A) and incubated with the DNA cellulose treated with the test solutions. TheDNA cellulose beads were washed with buffers to remove unbound protein, pelleted,resuspended in more buffer solution and boiled for 2 min to remove bound protein. TheDNA cellulose was then pelleted again, and the supernatant analyzed by gelelectrophoresis for the presence of bound HMG proteins which had recognized adductsof (or conformational changes to) DNA. The presence of protein in the supernatantimplies the existence of some interaction between the Ru-sulfoxide complex and DNA,the interaction being recognized by the HMG proteins.M5.5.7 The Isolation of Cellular DNA from Whole CHO CellsApproximately 3 x 106 CHO cells were incubated in solutions of the complexes,186washed and pelleted as described in Sections M5.5.2 and M5.5.3, and digested at 37°Covernight in a solution consisting of TNE (960 AL), proteinase K (Sigma, 10 AL of a10 mg/mL solution) and 10% sodium dodecyl sulfate (SDS, Aldrich, 10 AL). Thesolution was then extracted with two washes of TNE-equilibrated phenol (1 mL),followed by two washes in a 24:1 chloroform/iso-amyl alcohol solution (1 mL). TheDNA was precipitated by adding 99.5% ethanol (2 mL) and cooling the solution to -20°C for 2 h. The precipitated DNA was compacted by centrifugation (20,000 RPM,30 min at 4°C), the supernatant discarded and the pelleted DNA dried in air. The driedDNA was then re-hydrolysed in 200 AL TE and analyzed for Ru content using AAS;the amounts of Ru present were normalized to the amounts of DNA present which wasdetermined by measuring the optical density (OD) of the re-hydrolysed DNA solutions(diluted 100 fold) at 260 nm using a Cary lE UV-Vis Spectrophotometer. An 013260of 1.0 is equivalent to a DNA concentration of 50 Ag/mL [210].M5.5.8 Cell Toxicity Under Aerobic and Hypoxic ConditionsThe toxicities of the complexes toward CHO cells under air and under N2 weremeasured by comparing the plating efficiency of cells as a function of time afterincubation in solutions of the compounds (in a+/- media) with those incubated incontrol solutions as a function of time [211]. Solutions (a +/-) of the complexescontaining CHO cells (approximately 3.5 x105 cells/mL) were incubated for 4 h (seeSection M5.5.2); samples (0.5 mL) were taken at zero time (immediately following theaddition of the cells to the solution of the complexes) and then every hour after for 4187h. The sampled cells were diluted immediately in fresh a-/- media (10 mL, 4°C), andthe cells pelleted. The supernatant was decanted and the cells resuspended in fresh a-/-medium (10 mL, 4°C). An aliquot (2mL) of this cell solution was then diluted in PBS(10 mL), and the cell concentration determined using the Coulter counter.Aliquots of this cell solution (typically 20 AL, 250 - 300 cells) were then platedinto the Petri dishes (Falcon) prepared previously (filled with a +/+ medium (5 mL)and left for 24 h to equilibrate in a tray incubator (National Inc.) maintained at 37°Cwith a 95% air/5% CO2 gas flow); the dishes were then incubated in the tray incubatorfor 7 days for the cells to form colonies (defined as a group of >50 cells [13]). Thea +/ + medium was then discarded, and the colonies stained with methylene bluesolution for 7 min; the stain was then decanted, and the dishes rinsed with cold water.The number of colonies per dish was counted, and the plating efficiency (FE) calculatedas shown:number of coloniesPE—number of cells platedM5.5.9 Partition CoefficientsThe partition coefficients of the complexes between 1-octanol and water weredetermined at ambient temperatures following reported procedures [212]. Anhydrous1-octanol (BDH) was used as provided without further purification. The concentrationsof the complexes in the aqueous phase were determined using UV-Vis spectroscopy, andchosen so that the absorbances fell in the range 0.2 to 0.9 using a 0.5 cm quartz cell.188In a typical experiment, octanol saturated with distilled water and distilled watersaturated with octanol were prepared by shaking a mixture of the two and separating thetwo immiscible layers. The complex was dissolved in the aqueous layer, and the opticaldensity determined at an absorption maximum (see Chapter 2, p.39, for X max values).An equal volume of octanol was then added to the aqueous solution, and the mixtureagitated vigorously. The two phases were separated by centrifugation and the opticaldensity of the aqueous layer determined again; the concentration of complex present inthe octanol layer was obtained by difference. The partition coefficient (P) was calculatedas the ratio of the concentration of complex in the octanol and aqueous phases.189Chapter 6: Conclusions and Recommendations For Future Work6.1 The Evolution of the Project: From Ir to RuAreas of hypoxia in tumours present difficulties in the treatment of cancer(Section 1.4, p.4), and various modes of treatment have been developed in an effort toovercome this problem (e.g. the use of nitroimidazoles in conjunction with radiotherapy,see Section 1.9.2, p.14). Many nitroimidazoles, however, exhibit levels of toxicity thatoutweigh their therapeutic benefit. Previous work had shown that the toxicity of thesedrugs was reduced by coordination to cis-RuC12(DMS0)4 and cis-RuC12(TMS0)4, andthe SER of the free nitroimidazole increased using the metal to target the nitroimidazoleto DNA (Section 1.9.3, p.16). These Ru-sulfoxide-nitroimidazole complexes were,however, not structurally characterized [49,50].The converse approach was to be taken at the onset of this project;nitroimidazole complexes of Jr were to be synthesized, and the preferential reductionof nitroimidazoles in hypoxia was to be used to deliver the metal to these areas. Ifsuitable complexes of Jr were made, the long term goal was to use radioactive analoguesto deliver a radioisotope of Jr to hypoxic areas for the purposes of imaging or local cellkill (Section 1.10.3, p.19). Several nitroimidazole complexes of Jr were synthesized butcould not be purified; the details of these experiments are summarized in Appendix E.As mentioned above, several structural problems still remained from a previousinterdisciplinary project [137] which had used Ru(II) complexes of DMSO and TMSOas precursors to Ru-sulfoxide-nitroimidazoles for targeting the nitroimidazole to DNA.190More reports on the anti-tumour activity of cis- and trans-RuC12(DMS0)4 [124,201]and other Ru-DMS0 compounds [202] then appeared in the literature, and a decisionwas made to try and resolve some of the remaining structural questions, extend therange of sulfoxides used previously to include chelating ones, and to investigate theactivity (if any) of these Ru-sulfoxide complexes in vitro.6.2 Ru Complexes of DMSO and TMS0The intricate chemistry of these compounds became apparent almostimmediately. The "parent" compound, cis- RuC12(DMS0)4 was first prepared in thislaboratory in 1971 [106] and later characterized structurally also at UBC [107]. Thetrans-bromo isomer was also prepared at the same time [106] but not characterized until1984 [175]. During the course of this present work, reports on the synthesis andstructural characterization of the trans-chloro [121,124] and cis-bromo DMSOcomplexes were published [124]. The structures for all four monomeric Ru(II)-DMS0complexes have now been reported in the literature, and the synthetic and structuraldetails are discussed in Section 3.8.3 (p.82).The synthetic routes to some Ru(III)/DMS0 complexes in the literature [119]were also followed in an attempt to access Ru(III) complexes but the reactions were notalways reproducible (see Section 3.10.1, p.120); in one case, complexes of Rucontaining DMS instead of DMSO were obtained [121] (see Section 3.10.3, p.124). Thedetails, including a review of the chemistry of Ru-DMS0 complexes in the literature,are discussed in Section 3.8, p.74.191Two structural forms for cis-RuC12(TMS0)4 were isolated and characterizedstructurally in this present work, and the details published [171(a)]. The Trieste groupalso published structural details on one of the crystal forms of this complex [172(c)]simultaneously and independently of our group. The syntheses of trans-RuC12(TMS0)4and both cis and trans-RuBr2(TMS0)4 were also reported [172(c)] although nostructural data were included. The structure of trans-RuBr2(TMS0)4 was determinedas a part of this present work, and the details discussed in Section 3.9.3(b), p.107.Attempts to access Ru/Br/TMSO complexes via the use of LiBr withRuC13.3H20 resulted in the isolation and structural characterization of[RuBr3(TMS0)4Li]2 which contains four differently coordinated types of TMS0[171(b) & (c)]. The details pertaining to these Ru/TMSO complexes are discussed,including a review of the relevant literature, in Section 3.9, p.94. Ruthenium (III)complexes of TMS (analogous to the Ru(III)/DMS complexes) were also isolated andstructurally characterized during the course of this present work [171(a)] (Section3.10.2, p.123).6.3 Monodentate Sulfoxide Complexes of Ru(II) and Ru(III) (Other Than Those ofDMSO and TMSO)Various ruthenium complexes incorporating Et2S0, nPr2S0, nBu2S0, MePhS0and Ph2S0 as ligands were synthesized; mixed valence dinuclear species containingEt2S0, nPr2S0 and nBu2S0 were obtained as well as monomeric Ru(III) complexesof nPr2S0 and Ph2S0 ([H(nPr2S0)2][trans-RuC14(nPr2S0)2] and mer-192RuC13(Ph2S0)2(Me0H), respectively). Both complexes were structurally characterized.Of some interest, the protonated nPr2S0 is the third known example of such "sulfoxidecations" with structural data, [H(DMS0)2]+ [121,124] and [H(TMS0)]+ [172(c)]being the other two. The Ph2S0 complex includes, as part of its structure, acoordinated molecule of Me0H whose hydroxyl proton hydrogen bonds strongly withthe 0 atom of the S-bonded Ph2S0 ligand. The chemical and structural details of thesecomplexes are presented in Chapter 4 (p.126) of this thesis. The few reports on thesynthesis of other Ru(III)/nPr2SO/nBu2S0 complexes in the literature are also includedto review this field of chemistry as comprehensively as possible.6.4 Bidentate Sulfoxide Complexes of Ru(II)As mentioned previously, the range of sulfoxides used was extended to includebidentate ones in an effort to define the geometries of Ru-sulfoxide-nitroimidazolecomplexes (see Section 4.3, p.152). Four complexes of the general formulationRuC12(sulfoxide)2, where sulfoxide = BMSE, BESE, BPSE and BMSP, weresynthesized and characterized structurally. The geometries of the complexes were trans,cis, trans and cis respectively. To the best of our knowledge, these are the firstexamples of chelating sulfoxide complexes of Ru(II). The only other reported [197]examples of complexes with such ligands (BMSE and BPSE) are those of the first rowtransition metals, and Pd and Pt; no structural data were reported.The structural details of the Ru complexes containing chelating sulfoxide ligandsare discussed in Sections 4.3 - 4.3.6 (pages 152-164), and are a valuable addition to the193data base for such complexes. The compounds were also used as precursors toRuichelating-sulfoxide/nitroimidazole complexes, and the synthetic details aresummarized briefly in Appendix E. The mixtures obtained in these reactions could not,however, be purified.6.5 The Cellular Accumulation of Selected Ruthenium-Sulfoxide Complexes in CHOCellsA preliminary investigation into the biological activity of selected complexes wasinitiated in the later stages of the project. The target for cell kill is considered to beDNA, so the ability of the complexes to traverse the cell membrane and bind to DNAwas the primary focus of the experiments. The results (discussed in Chapter 5, p.166)indicate that the selected complexes all accumulate in CHO cells, and that greateramounts of the trans complexes accumulated in the cells than the cis. No significantdifferences were observed in the amounts of complex that accumulated in cells incubatedunder air or N2.The complexes all bind to DNA (in whole cells and isolated samples) and, ofconsiderable interest, the adducts formed between the trans complexes and DNA wererecognized by HMG proteins in the damaged DNA precipitation assay (Section 5.3.5(a),p.175). Adducts formed with the cis complexes were also recognized by the proteins butthe interactions appeared to be weaker relative to those formed from the transcomplexes. The assay has also been used to investigate interactions between various Ptcomplexes and DNA [203(b) & (c)], but the HMG proteins appear to recognize damage194due only to the cis-isomers; to date, no adducts due to trans-Pt complexes have beendetected by the assay [213]. The nature of these metal-DNA interactions are still notwell understood, and further studies are required.The Ru-sulfoxide complexes were found to be non-toxic toward CHO cells at theconcentrations used despite binding to DNA. The reasons for this are still unclear;perhaps the lesions are easily repaired or the levels of complex required for toxicitywere not achieved at the concentrations used. The accumulation, binding characteristicsand the lack of toxicity shown by these complexes (especially of the trans-complexes)indicate that they have good potential as "carriers" for targeting nitroimidazoles to DNA(see Section 1.9.3, p.16). The cis-isomers of RuC12(DMS0)4 and RuC12(TMS0)4 wereused for this purpose in previous studies [49,50], and the data obtained from this presentwork indicate that using the trans-isomers as precursors may be more beneficial due toincreased levels of accumulation in the cell and binding to DNA.6.6 Suggestions for Future WorkThe present series of chelating sulfoxide complexes of Ru(II) should becompleted and expanded; thus cis-RuC12(BMSE)2, trans-RuC12(BESE)2 and cis-RuC12(BPSE)2 should be synthesized and characterized using, as precursors, cis- andtrans-RuC12(DMS0)4, in sulfoxide exchange reactions. The synthesis of the bromo andiodo analogues should also be initiated to complete the data base for these complexes.The effects of varying the length of the carbon backbone of the chelating sulfoxidesshould also be further studied. More extensive in vitro studies should be undertaken to195understand better the effects of changes in geometry, alkyl chain length and halide onthe accumulation, DNA binding and toxicity of the complexes in vitro.The results obtained from the damaged DNA precipitation assay imply that theRu-sulfoxide-DNA adducts formed by metal-DNA binding or conformational changesin the double helix may be similar to those of cisplatin. The exact nature of theinteraction between the Ru-complexes and DNA should be investigated morethoroughly. The use of high resolution 1H NMR spectroscopy on solutions of thesecomplexes with base pairs in conjunction with molecular modelling studies may be ofuse. Such studies may help explain the apparent lack of toxicity of these Ru-compounds(unlike the Pt complexes) despite their ability to bind to DNA.The cell accumulation studies presented in Section 5.3.3 (p.169) provide someinformation on the accumulation characteristics of the complexes by CHO cells. 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Skov. Radiat. Res.119, 145 (1989).212Appendix A: Methods and Materials for Biological ExperimentsA-1 Preparation of Stock SolutionsA-1(a) a MediaAn alpha-modification of Eagle's minimum essential medium (MEM, Gibco) wasused in all procedures involving the maintenance or incubation of CHO cells. Threedifferent forms of the media were used, a-/-, a+/- and a +/ + depending on therequirements of the procedure.One packet of a-media powder and 10,000 units of Penstrep antibiotic (Gibco)were added to 10 L of double distilled water and the solution stirred for 2 h at roomtemperature to make a-/-.Foetal bovine serum (10%, Gibco) and NaHCO3 (20 g) were added to a-/-media, and the pH of the resulting solution adjusted to 7.30 with 4 M NaOH to producea +/ + media. Both batches of media were sterilized by filtration (0.22 uM pore size)under pressure; the filtered solutions were dispensed into sterile 500 mL bottles and keptat 4°C. Each batch was tested for contamination (by incubating 15 mL samples at 37°Cfor a week) and the ability to maintain proper cell growth.The a+/- medium was made up as required by adding foetal bovine serum(10%, 50 mL) to a-/- (500 mL). The solution was refiltered before use (0.22 Am) toensure solution sterility before use. Stock media were stored at 4°C.A-1(b) Phosphate Buffer Saline SolutionsNaC1 (160 g), KC1 (4 g), Na2HPO4 (23 g) and KH2PO4 (4 g) were dissolved213in distilled water (20 L), and the solution sterilized by filtration through a 0.22 Am filter(Nalgene). The solution was stored at room temperature and cooled when required.A-1(c) Methylene-Blue SolutionMethylene-blue (2 g) was dissolved in distilled water (1 L), and the solutionallowed to stand for one hour prior to filtration. The methylene blue solution wasfiltered after use in toxicity experiments and re-used several times before beingdiscarded.A-1(d) "EDTA" SolutionStock solutions (3 M) were prepared from the disodium salt of H4EDTA(Sigma); the pH of the solutions was adjusted to 8.00 with NaOH (4 M), and thesolutions were diluted as required in experiments.A-1(e) Trizma Buffers (Tris-HC1 Solutions)Tris stock solutions were prepared from Trizma-HC1 (Sigma), and the pH of thesolutions adjusted to 7.50 - 8.00 using 4 M NaOH. Stock solutions (4 M) were dilutedas required for use in experiments or other solutionsA-1(f) Tris-EDTA (TE) SolutionsStock solutions of TE (0.5 M Tris-HC1 and 50 mM EDTA) were prepared, andthe pH of the solutions adjusted to 8.00 with 4 M NaOH. The stock solutions were then214diluted to the appropriate concentrations as required.A-1(g) TNE SolutionsTNE was prepared from stock solutions and had a final composition of 10 mM Tris-HCI, 150 mM NaC1 and 10 mM EDTA. The final pH of the solution was 8.00.A-1(h) TNE-Equilibrated PhenolPure phenol (99%, Aldrich) was liquefied by heating in a water bath andsaturated with an equal volume of 0.5 M Tris-HC1 (pH 8.00), and then the two phaseswere allowed to separate. The aqueous layer was discarded and the process repeatedwith fresh Tris-HC1 solutions until the pH of the phenol layer was 7.00 (measured withpH paper). The TNE-equilibrated phenol was then transferred into 50 mL polypropylenetubes and stored at -20°C in darkness. The frozen stock was thawed to roomtemperature just prior to use in the DNA extraction experiments.A-1(i) HEPES SolutionsStock solutions (2 M) of N-2-hydroxyethylpiperazine-N'-2-ethane sulfonic acid(HEPES, Research Organics Inc.) were made up in distilled water, and the pH adjustedto 7.40 with 2 M NaOH. The solution was then sterilized by filtration (Nalgene, 0.22g111) prior to use in experiments.215A-2 Atomic Absorption StandardsThe ruthenium standards (980 itg/mL) were provided by Sigma and diluted withdoubly distilled water to give a stock concentration of 900 ng/mL. The stock solutionwas further diluted with doubly distilled water to the appropriate standard concentrationsfor the determination; doubly distilled water was used for the blank.The matrix conditions (amount of cell debris and acid concentration) were varied toexamine the effect on the signal of the analyte. The variation in signal was insignificant.A-3 Sampling ConditionsSamples were digested in concentrated HNO3, and the solution diluted six-foldwith distilled water before analysis for Ru with AAS. The samples were loaded into anautomated carousel system, and 20 AL of the samples were placed in the graphite tubefurnace using an automated sampling arm. No significant amounts of Ru were found inthe blanks (cells incubated in a+/- media with no complex present).A-4 Furnace ParametersThe furnace parameters used in the drying, ashing and atomization stages of theanalysis are tabulated below in Table A.1. The parameters used were optimized for thecell membrane/acid matrix used in the determination.216Table A.1 Furnace Parameters used in AASStep Temp (°C) Time (sec) Gas Gas Flow(L/min)Read Command1. 90 20.0 Ar 3.0 No2. 100 5.0 Ar 3.0 No3. 100 30.0 Ar 3.0 No4. 1000 5.0 Ar 3.0 No5. 1000 5.0 Ar 3.0 No6. 1000 0.5 Ar 0.0 No7. 2800 1.0 Ar 0.0 Yes8. 2800 2.0 Ar 0.0 Yes9. 2800 2.0 Ar 3.0 NoA-5 The Damaged DNA Precipitation AssayA-5(a) Preparation of DNA CelluloseCalf thymus double stranded-DNA cellulose (Sigma, 100 mg) was incubated for24 h at 37°C, in solutions (10 mL) of the complex in a phosphate buffer consisting of1 mM NaHPO4 (7.40 pH) and 3 mM NaC1 with continuous agitation; the solutionswere kept in darkness to prevent UV induced damage. The DNA cellulose suspensionwas then washed five times with a 1 mL solution of 20 mM Tris-HC1 (pH 8.00), 1 mMEDTA and 500 mM NaC1, followed by a final wash (1 mL) with 10 mM Tris-HC1 (pH8.00) at 4°C. Damaged DNA cellulose was stored in 10 mM Tris-HC1 (2 mL, pH 8.00)at 4°C.A-5(b) The Isolation of the HMG ProteinsV79 cells, grown as monolayers in Eagle's a-minimum essential media (+ 10%fetal calf serum) were trypsinized (0.1% aq. soln., 2 min), washed twice with PBS and217finally suspended in ice cold PBS. All subsequent steps were performed at 4°C tominimize degradation of the protein. The cells were pelleted by centrifugation andresuspended in a buffer solution consisting of 10 mM HEPES (pH 7.9), 1.5 mMMgC12, 10 mM KC1, 0.5 mM DTT, 0.5% NP-40 (a non-ionic detergent) and 1 mMphenyl methyl sulfonyl fluoride (PMSF) (five times the volume of the cell pellet). Themixture was left over ice for 10 min at 0°C and then pelleted by centrifuge. The cellswere resuspended in two times the cell volume of the same buffer solution andtransferred into a Dounce homogenizer (B type pestle), and the cells lysed with tenstrokes of the pestle. The resulting suspension was centrifuged (10 min, 2000 RPM) topellet the nuclei. The supernatant (cytoplasmic fractions) was retained and mixed witha solution (1/10 of the pellet volume) of 0.3 M HEPES (pH 7.9), 1.4 M KC1, and 0.03M MgCl2, and the solution centrifuged for 60 min at 10 000 G to pellet the nuclei. Thesupernatant from this high speed spin was then dialysed for 10 h against 20 mM HEPES(pH 7.9), 20% (v/v) glycerol, 0.1 M KC1, 0.2 mM EDTA, 0.5 mM PMSF and 0.5 mMDTT.The nuclei were pelleted further using a high speed ultracentrifuge (25 000 G,20 min) and the supernatant discarded. The pellet was then resuspended in 3 mL of 20mM HEPES (pH 7.9), 20% (v/v) glycerol, 0.42 M NaC1, 1.5 mM MgC12, 0.2 mMEDTA, 0.5 mM PMSF and 0.5 mM DTT (per 109 cells). The resulting suspension washomogenized with 10 strokes in a Dounce homogenizer (B type pestle), left over ice for20 min and then centrifuged for 20 min at 25 000 G. The resulting supernatant wasdialysed for 10 h against 20 mM HEPES (pH 7.9), 20 % (v/v) glycerol, 0.1 M KC1,2180.2 mM EDTA, 0.5 mM PMSF and 0.5 mM DTT.A-5(c) The Damaged DNA-Affinity Precipitation AssayTypically, the isolated protein (10 AL) was added to treated DNA cellulose (30AL), and the mixture incubated for 60 min at 4°C. The sample was then centrifuged for5 min at 10 000 G, and the DNA-cellulose pellet washed five times with 1 mL of asolution consisting of 10 mM Tris-HC1 (pH 7.90), 0.5 M NaC1, 1 mM EDTA, 0.5 mMDTT, 10% glycerol and 0.1% NP-40. The five washes were followed with a final washin 10 mM Tris-HC1 (pH 6.80), and the proteins still bound to the DNA cellulose wereremoved by boiling the sample for 2 min in a solution of 0.5 M Tris-HC1 (pH 6.80),10% SDS (sodium dodecylsulfate), 0.1% bromophenol blue, 20% glycerol and 5% 2-mercaptoethanol. The mixture was centrifuged at 10 000 G for 2 min, and thesupernatant analyzed for the presence of proteins using gel electrophoresis.A-5(d) Gel ElectrophoresisOne dimensional sodium dodecyl sulfate-polyacrylamide electrophoresis (100V,current constant, running time = 2 h) was performed with polyacrylamide 12.5% mini-gels (Novex, 800 by 800 by 1.5 mm, 15 wells). The gels were then stained for 30 minwith a 0.1% (w/v) Coomassie blue solution (also known as "Brilliant Blue", Sigma) andthen destained overnight with 10% (v/v) ethanol and 7.5% (v/v) acetic acid.2196l'f'l^I1^2^3^4^5Time (h)so-0- Mr-a- Hypoxic-6- Air,  +HEPESHypoxic, +HEPES40 -10 --a- Mr-a- Hypoxic-6- Air,  +FIEPES-a- Hypoxic, +HEPES200Appendix B: Accumulation Profiles for Selected Ruthenium Sulfoxide ComplexesFigure B.1 Accumulation of cis-RuC12(DMS0)4 (1) at1.0 mM in CHO cells0^1^2^3^4^5^6Time (h)Figure B.2 Accumulation of trans-RuC12(DMS0)4 (2) at1.0 mM in CHO cells220—o— Air—6— Hypoxic- 6- Air,  +HEPES—+— Hypoxic, +HEPIIS200--0-- Air—a— Hypoxic—A— Air, +HEPES—*— Hypoxic, +HEPES1000^1^2^3^4^5^6Time (h)Figure B.3 Accumulation of cis-RuC12(TMS0)2 (3) at 1.0mM in CHO cells0^1^2^3^4^5^6Time (h)Figure B.4 Accumulation of trans-RuC12(BMSE)2 (4) at1.0 mM in CHO cells221-0- Air-IF- Hypoxic-6- Air,  +HEPES—a-- Hypoxic, +HEPES30200^1^2^3^4^5^6Time (h)Figure B.5 Accumulation of cis-RuC12(BMSP)2 (7) at 1.0mM in CHO cells222-6- Contr ol air- *-- Control hypoxic-o-1 air- o- 1 hypoxic-6- Control air-- Control hypoxic-Er 2 air-E- 2 hypoxic542^3Time (h)10,01Appendix C: Toxicity Data for Selected Ruthenium Sulfoxide ComplexesFigure C.1 The toxicity of cis-RuC12(DMS0)4 (1) at 1.0mM, PE vs. TimeFigure C.2 The toxicity of trans-RuC12(DMS0)4 (2) at1.0 mM, PE vs. Time223I-6- Control air-6- Control hypoxic-0-3 air-.-3 hypoxicA 7-,010^1^2^3^4Time (h)Figure C.3 The toxicity of cis-RuC12(TMS0)4 (3) at 1.0mM, PE vs. TimeI-6- Control air-6- Control hypoxic-ci- 4 air-s- 4 hypoxic,1 -_,01 I^I^i^I^I0^1^2^3^4Time (h)Figure C.4 The toxicity of trans-RuC12(BMSE)2 (4) at1.0 mM, PE vs. Time224430 I^2Time (h)—a— Control air—.— Control hypoxic—0-5 air—s— 5 hypoxic,01-_ _-- 6- Control air—e— Control hypoxic—o— 6 air—s— 6 hypoxic--____1^1^12Time (h)I3^4Figure C.5 The toxicity of cis-RuC12(BESE)2 (5) at 0.50mM, PE vs. Time1,01Figure C.6 The toxicity of trans-RuC12(BPSE)2 (6) at0.50 mM, PE vs. Time225Appendix D: Experimental Details, Final Atomic Coordinates, Bond Lengths andAngles for the Crystal StructuresD-1 Crystal Data and Results for cis-RuC12(TMS0)4, form AD-2 Crystal Data and Results for cis-RuC12(TIVIS0)4, form 12The experimental details, final atomic coordinates, bond lengths and angles for cis-RuC12(TMa0)4 (forms A and b) are published in ref. 171(a).D-3 Crystal Data and Results for [RuBr3(TMS0)4Li]2The experimental details, final atomic coordinates, bond lengths and angles for[RuBr3(TMS0)4Li12 are published in ref. 171(b) & (c).226Appendix D^ Trans-RuBr2(TMS0)4D-4 Crystal Data and Results for trans-RuBr2(TMS0)4D-4(a) Experimental DetailsA. Crystal DataEmpirical Formula^ C16H32Br20 4 RuS 4Formula Weight 677.54Crystal Color, Habit^ yellow-orange, irregularCrystal Dimensions (mm) 0.250 X 0.300 X 0.400Crystal System^ tetragonalNo. Reflections Used for UnitCell Determination (20 range)^25 ( 40.6 - 46.10)Omega Scan Peak Widthat Half-height^ 0.38Lattice Parameters:a =^10.4240 (6)Ac =^10.853 (1)AV = 1179.3 (2)A3Space Group^ 14/m (#87)Z value 2Dcalc^ 1.908 g/cm 3F000 676P(MoKa)-143.68 cmB. Intensity MeasurementsDiffractometer^ Rigaku AFC6SRadiation MOKa (A = 0.71069 A)Temperature^ 21°CTake-off Angle 6.0°Detector Aperture^ 6.0 mm horizontal6.0 mm verticalCrystal to Detector Distance^285 mm227Appendix D^ Trans-RuBr2(TMS0)4Experimental Details (cont.)Scan Type^ w-219Scan Rate 32.0°/min (in omega)(8 rescans)Scan Width^ (1.47 + 0.35 tane)°29max 80.0°No. of Reflections Measured^Total: 2052Unique: 1906 (Riot^.035)Corrections Lorentz-polarizationAbsorption(trans. factors:^0.75 - 1.00)Secondary Extinction(coefficient:^0.154(6) E-05)C. Structure Solution and RefinementStructure Solution^ Patterson MethodRefinement^ Full-matrix least-squaresFunction Minimized^ w (IF01 - IFc1) 2Least-squares Weights 4Fo 2/o 2 (Fo 2 )p-factor^ 0.00Anomalous Dispersion^ All non-hydrogen atomsNo.^Observations^(I>3.00a(I))No. VariablesReflection/Parameter RatioResiduals:^R; RwGoodness of Fit IndicatorMax Shift/Error in Final Cycle10624623.090.034; Peak in Final DAL MapMinimum Peak in Final Diff. Map1.07 e-/A3-0.80 e-/A3228Appendix D^ Trans-RuBr2(TMS0)4D-4(b) Final Atomic Coordinates (fractional) and Batom x Y z Beg occ.Ru(1) 0 0 0 1.81(1)Br(1) 0 0 0.23245(5) 3.64(1)S(1) 0.03932(8) 0.22048(8) 0 2.81(3)0(1) -0.0781(3) 0.2978(3) 0 7.7(2)C(1) 0.1378(4) 0.2859(3) 0.1215(3) 4.9(2)C(2) 0.1864(9) 0.4111(9) 0.075(1) 4.2(4) 0.50C(2A) 0.233(1) 0.379(1) -0.052(1) 5.8(6) 0.50*B eg (8/3)n2 Mi. .a.*a1]^1^3 *(a.-a.)1^D229Appendix D^ Trans-RuBr2(TMS0)4D-4(c) Bond Lengths (A) and Angles (*) with Estimated Standard Deviationsatom^atom^distance atom atom^distanceRu(1)^Br(1)^2.5228(7) C(1) C(2)^1.49(1)Ru(1)^S(1)^2.3345(9) C(1) C(2A)'^1.58(1)S(1)^0(1)^1.466(3) C(2) C(2A)^1.504(9)^S(1)^C(1)^1.805(3)atom^atom^atom^angle atom atom^atom^angleBr(1)^Ru(1)^Br(1)'^180.0 C(1) 5(1)^C(1)'^93.9(2)Br(1)^Ru(1)^S(1)^90.0 5(1) C(1)^C(2)^106.1(5)S(1)^Ru(1)^S(1)"^180.0 S(1) C(1) C(2A)'^104.1(5)S(1)^Ru(1)^S(1)*^90.0 C(1) C(2) C(2)'^109.8(5)Ru(1)^S(1)^0(1)^113.3(1) C(1) C(2)^C(2A)^103.3(8)Ru(1)^S(1)^C(1)^118.1(1) C(1) C(2A)^C(2)'^111(1)0(1)^S(1)^C(1)^105.5(2)Here and elsewhere the symbolsoperations:^x,^y,^-z:^-x,^-y,',z;",^andand -y,*x,refer to symmetryz;^respectively.230Appendix D^ Trans-RuBr2(TMS0)4D-4(d) Trans-RuBr2(TME0)4 Showing 50% Probability Thermal EllipsoidsD-4(e) The Asymmetric Unit in trans-RuBr2(TMS0)4231Appendix D^ [H(nPr2S0)2][trans-RuC14(nPr2S0)2]D-5 Crystal Data and Results for [H('sPr2SQ)2]+[trans-RuC14(nPr2S0)2]-D-5(a) Experimental DetailsA. Crystal DataEmpirical Formula^ C 24 H 57 C1 4 0 4 S 4 RuFormula Weight 780.83Crystal Color, Habit^ orange, prismCrystal Dimensions^(mm)Crystal SystemNo.^Reflections Used for Unit0.080 X^0.120^X^0.200triclinicCell^Determination^(2e range) 25^(^66.3 -^81.9°)Omega Scan Peak Widthat Half-height 0.43Lattice^Parameters:a - 9.952^(2)Ab^•. 10.166^(2)Ac^... 9.685^(1)Aa^.0 102.30^(1)°0^6' 101.21^(2)°Y 97.60^(2)°v . 923.4^(3)A3Space Group PI^(#2)Z value 1Dcalc 1.404 g/cm3409F000P(C u xa)85.53 -1cmDiffractometerRadiationTemperatureTake-off AngleB. Intensity MeasurementsRigaku AFC6SCulkm (X^1.54178 A)21°C6.0°232Appendix D^ [H(nPr2S0)2][trans-RuC14(nPr2S0)2]Experimental Details (cont.)Detector Aperture^ 6.0 mm horizontal6.0 mm verticalCrystal to Detector Distance^285 mmScan Type^ 0-28Scan Rate 8.0/min (in omega)(8 rescanS)Scan Width^ (1.00 + 0.20 tan8)°219max 155.5°No. of Reflections Measured^Total: 3994Unique:^3764 (Rint^.025)Corrections Lorentz-polarizationAbsorption(trans. factors:^0.73 - 1.00)Decay (-10.00% decline)Secondary Extinction(coefficient:^0.62549E-05)C. Structure Solution and RefinementStructure Solution^ Patterson MethodRef nement^ Full-matrix least-squaresFunction Minimized^ I w (1Fol - IFc1) 2Least-squares Weights 4Fo 2/o 2 (Fo 2 )p-factor^ 0.01Anomalous Dispersion^ All non-hydrogen atomsNo.^Observations^(I>3.00o(I))No.^VariablesReflection/Parameter RatioResiduals:^R;^RwGoodness of^Fit IndicatorMax Shift/Error^in Final^Cycle322217118.840.034;2.780.010.041Maximum Peak in Final Diff. MapMinimum Peak in Final Diff. Map0.62 e-/A!-0.48 e-/A'233Appendix D^ [H(nPr2S0)21[trans-RuC14(nPr2S0)2]D-5(b)atomFinal^Atomic Coordinates (fractional)^and Beg^(A2)*B eqRu(1) 1/2 1/2 1/2 3.63(1)C1(1) 0.47198(9) 0.31287(8) 0.60574(9) 4.92(3)C1(2) 0.45898(9) 0.35325(8) 0.26679(7) 4.84(3)5(1) 0.25785(8) 0.50344(8) 0.48408(8) 4.33(3)0(1) 0.2027(3) 0.4913(3) 0.6120(3) 6.5(1)C(1) 0.1478(4) 0.3752(4) 0.3323(4) 5.0(1)C(2) 0.1471(4) 0.2309(4) 0.3494(4) 5.9(1)C(3) 0.0614(5) 0.1272(5) 0.2149(6) 8.1(2)C(4) 0.2037(4) 0.6516(4) 0.4322(4) 5.3(1)C(5) 0.2532(5) 0.7811(4) 0.5485(4) 6.4(2)C(6) 0.2055(6) 0.9024(5) 0.4947(6) 8.5(2)5(2) 0.80026(9) 0.4280(1) 0.07021(8) 4.90(3)0(2) 0.8786(3) 0.4464(3) -0.0509(3) 6.4(1)C(7) 0.6600(4) 0.2905(4) -0.0241(4) 5.1(1)C(8) 0.7095(5) 0.1559(5) -0.0689(6) 7.4(2)C(9) 0.5944(6) 0.0454(5) -0.1666(6) 8.4(2)C(10) 0.7082(4) 0.5669(4) 0.0869(3) 4.8(1)C(11) 0.8126(5) 0.7023(5) 0.1464(5) 7.2(2)C(12) 0.7436(6) 0.8200(5) 0.1406(6) 8.7(2)*8eq • (8/3)n2 IIU..a *a *(a..a.)13 i^j^3234Appendix D^ [H(nPr2S0)2][trans-RuC14(nPr2S0)2]D-5(c) Bond Lengths (A) with Estimated Standard Deviationsatom atom distance atom atom distanceRu(1) C1(1) 2.3549(8) C(5) C(6) 1.534(6)Ru(1) C1(2) 2.3533(8) 5(2) 0(2) 1.559(2)Ru(1) S(1) 2.390(1) 5(2) C(7) 1.784(4)5(1) 0(1) 1.471(2) 5(2) C(10) 1.779(4)S(1) C(1) 1.800(4) C(7) C(8) 1.520(5)S(1) C(4) 1.801(4) C(8) C(9) 1.502(7)C(1) C(2) 1.510(5) C(10) C(11) 1.536(5)C(2) C(3) 1.510(6) C(11) C(12) 1.462(7)C(4) C(5) 1.491(5)235Appendix D^ [H(nPr2S0)2][trans-RuC14(nPr2S0)2]D-5(d) Bond Angles (*) with Estimated Standard Deviationsatom atom atom angle atom atom atom angleC1(1) Ru(1) C1(1)' 180.00 0(1) S(1) C(4) 106.3(2)C1(1) Ru(1) C1(2) 91.55(3) C(1) S(1) C(4) 97.8(2)C1(1) Ru(1) C1(2)' 88.45(3) S(1) C(1) C(2) 113.5(3)C1(1) Ru(1) S(1) 87.51(3) C(1) C(2) C(3) 111.2(4)C1(1) Ru(1) S(1)' 92.49(3) 5(1) C(4) C(5) 114.0(3)C1(2) Ru(1) C1(2) ' 180.00 C(4) C(5) C(6) 110.7(4)C1(2) Ru(1) S(1) 93.02(3) 0(2) 5(2) C(7) 102.3(2)C1(2) Ru(1) S(1)' 86.98(3) 0(2) S(2) C(10) 103.5(2)S(1) Ru(1) 5(1)' 180.00 C(7) S(2) C(10) 99.9(2)Ru(1) S(1) 0(1) 117.9(1) 5(2) C(7) C(8) 112.4(3)Ru(1) S(1) C(1) 112.6(1) C(7) C(8) C(9) 112.2(4)Ru(1) S(1) C(4) 113.5(1) S(2) C(10) C(11) 109.4(3)0(1) S(1) C(1) 106.7(2) C(10) C(11) C(12) 111.4(4)* Here and elsewhere, primes refer to symmetry operation:1-z, 1-y, 1-z.236C12 C11 Ca• •• •C3Appendix D^ [H(nPr2S0)2][trans-RuC14(nPr2S0)2]D-5(e) Stereoviews for [H(nPr2SQ)2][RuC14(nPr2S0)2] and the Unit Cell237Appendix D^ RuC13(Ph280)2(Me0H)D-6 Crystal Data and Results for RuC13(Ph2S0)2(111e0H)D-6(a) Experimental DetailsA. Crystal DataEmpirical Formula^ C 25H24 C1 3 0 3 RuS 2Formula Weight 644.01Crystal Color, Habit^ orange, irregularCrystal Dimensions (mm) 0.080 X 0.200 X 0.250Crystal System^ monoclinicNo. Reflections Used for UnitCell Determination (29 range)^25 ( 55.1 - 63.9°)Omega Scan Peak widthat Half-height^ 0.37Lattice Parameters:a =^9.503 (1)Ab =^19.531 (2)Ac =^14.672 (2)A0^100.49 (1)°V = 2678 (1)A3Space Group^ P21 /c (#14)Z value 4Dcalc^ 1.597 g/cm3F000 1300P(CuKa)^ 93.33 cm-1B. Intensity MeasurementsDiffractometer^ Rigaku AFC6SRadiation CuKa (X = 1.54178 A)Temperature^ 21°CTake-off Angle 6.0°Detector Aperture^ 6.0 mm horizontal6.0 mm vertical238Appendix D^ RuC13(Ph2S0)2(Me0H)Experimental Details (cont.)Crystal to Detector Distance^285 mmScan Type^ w-2eScan Rate 8.0°/min (in omega)(8 rescans)Scan Width^ (0.89 + 0.20 tame).12(9max 55.2°No. of Reflections Measured^Total: 5861Unique: 5549 (Riot^.021)Corrections^ Lorentz-polarizationAbsorption(trans. factors:^0.40 - 1.00)Secondary Extinction(coefficient:^0.33(2) E-06)C. Structure Solution and RefinementStructure Solution^ Patterson MethodRefinement^ Full-matrix least-squaresFunction Minimized^ E w (IFol - IFcI) 2Least-squares Weights 4Fo 2 /a 2 (Fo 2 )p-factor^ 0.00Anomalous Dispersion^ All non-hydrogen atomsNo.^Observations^(I>3.00a(I))No.^VariablesReflection/Parameter RatioResiduals:^R;^RwGoodness of Fit IndicatorMax Shift/Error in Final Cycle415531213.320.030; Peak in Final Diff. Map^0.49 e-/A.!Minimum Peak in Final Diff. Map^-0.62 e-/A'239Appendix D^ RuC13(Ph2S0)2(Me0H)D-6(b) Final Atomic Coordinates (fractional) and Batom x z BeqRu(1) 0.05436(3) 0.12868(1) 0.15365(2) 3.54(1)C1(1) -0.1148(1) 0.21425(5) 0.11522(7) 4.84(4)C1(2) 0.2217(1) 0.03964(5) 0.17028(8) 5.41(4)C1(3) 0.1679(1) 0.18096(5) 0.28753(7) 5.13(4)5(1) -0.10411(8) 0.06558(4) 0.21275(6) 3.64(3)S(2) 0.3479(1) 0.18280(5) 0.10745(6) 4.15(4)0(1) -0.1989(3) 0.0289(1) 0.1365(2) 4.5(1)0(2) 0.1851(2) 0.1864(1) 0.0791(2) 4.7(1)0(3) -0.0332(3) 0.0831(1) 0.0268(2) 5.2(1)C(1) -0.0293(4) 0.0005(2) 0.2938(2) 4.0(1)C(2) 0.0677(5) 0.0158(2) 0.3727(3) 5.8(2)C(3) 0.1178(6) -0.0372(3) 0.4326(3) 6.6(2)C(4) 0.0726(5) -0.1023(2) 0.4124(3) 6.1(2)C(5) -0.0223(6) -0.1171(2) 0.3340(4) 6.4(2)C(6) -0.0747(4) -0.0651(2) 0.2734(3) 5.2(2)C(7) -0.2202(4) 0.1080(2) 0.2794(2) 3.9(1)C(8) -0.3507(4) 0.0767(2) 0.2802(3) 5.2(2)C(9) -0.4443(4) 0.1064(3) 0.3293(3) 6.1(2)C(10) -0.4075(5) 0.1661(3) 0.3764(3) 6.3(2)C(11) -0.2782(5) 0.1965(2) 0.3765(3) 6.0(2)C(12) -0.1822(4) 0.1677(2) 0.3266(3) 5.0(2)C(13) 0.4096(4) C^--'3'21 0.0080(2) 4.0(1)C(14) 0.3578(4) 0.1774(2) -0.0791(3) 5.1(2)C(15) 0.4114(5) 0.1504(2) -0.1536(3) 5.8(2)C(16) 0.5132(5) 0.0997(2) -0.1391(3) 5.9(2)C(17) 0.5625(5) 0.0756(2) -0.0538(3) 6.0(2)240Appendix D^ RuC13(Ph1S0)2(Me0H).1Final Atomic Coordinates (fractional) and B ^(cont.)atom B eqC(18) 0.5113(4) 0.1011(2) 0.0215(3) 5.2(2)C(19) 0.4017(4) m^ncooil,......--,.., 0.10,7(3) 4.4(2)C(20) 0.5431(4) 0.2850(2) 0.1370(3) 5.7(2)C(21) 0.5886(6) 0.3516(3) 0.1366(4) 7.6(3)C(22) 0.4940(8) 0.4021(3) 0.1020(4) 8.3(3)C(23) 0.3553(6) 0.3862(3) 2.0662(4) 8.8(3)C(24) 0.3064(5) 0.3193(2) 2.0693(3) 6.4(2)C(25) -0.0374('' 0.1131(3) -0.0616(3) 8.2(3)•B eq • (8/3)71`2ZU^a.*a •(a •a )ID^D^3241Appendix D^ RuCI 3 (Ph2S0)2(Nie0H)D-6(c) Bond Lengths (A) with Estimated Standard Deviationsatom atom distance atom atom distanceRu(1) C1(1) 2.3165(9) 2:-) C(8) 1.384(5)Ru(1) C1(2) 2.339(1) 2:7) C(12) 1.372(5)Ru(1) C1(3) 2.301(1) 2(8) C(9) 1.372(6)Ru(1) 5(1) 2.2391(9) 2:9) C(10) 1.368(7)Ru(1) 0(2) 2.122(2) 2(10) 2(11) 1.364(7)Ru(1) 2(3) 3.294(3) 0(12) 1.389(5)5(1) 2(1' 1.485(2) 2!13 :!14) 1.373(5)(1) (" 1.797H;) 2:11Y 2(18) 1.379(5)S(1 1.503(3) 2(14) 2:15) 1.392(6)S(2) 2(2) 1.529(2) 2(15) 2(16) 1.373(6)S(2, 2(13) 2(16) 2:17) 1.340(6)5(2) C(19) 1.751;4) 0(17) 0(18) 1.378(6)0(3) C(25) 1.415(5) 0(19) C(20) 1.377(5)C(1) C(2) 1.375(5) 2(19) C(24) 1.354(6)C(1) C(6) 1.366(5) 2(20) 0(21) 1.373(7)C(2) C(3) 1.385(6) 2(21) C(22) 1.368(8)C(3) C(4) 1.357(6) 0(22) 0(23) 1.357(9)C(4) C(5) 1.357(6) C(23) 0(24) 1.387(7)C(5) C(6) 1.382(6)242Appendix D^ RuC13(Ph2S0),(Nte0H)D-6(d) Bond Angles (°) with Estimated Standard Deviationsatom atom at: m angle at atsn atom angleC1(1) Ru(1) C1(2 172.03(4) C(1; ,..... :(3) 118.2(4)C1(1) Ru(1) C1(2 94.84(4) C(2) 2: 2(4) 120.2(4)C1(1) Bu(l) S(1; 90.31(3) C(3) C(4) C(5) 121.3(4)C1(1) Ru(1) 0(2) 86.39(7) C(4) C(5) C(6) 119.7(4)C1(1) Ru(1) 0(3' 86.82(9) C(1) C(6) C(5) 119.1(4)C1(2 Ru(1) C1(3 9.2.11(4) S(1) f7:-. C(8) 116.1(3)C1(2) Ru(1 l' 92.44(3) S(1) C(12) 122.2(3)F. C.2i ..9.69(7' -'''' 121.7(4)C.12) Ru(1' : ES.93(9) C7 - :(9' 119.0(4)C1(3: Rul, S:_ ?9.06(4 :.."E' C(10) 119.7(4)C1' Ru(l` ^(2 68.66(8) 0(9) C(.1C) C(11) 121.3(4)C1(3) F.0 '-) H 175.02(6) C(10) ,..^r.7, 0(12; 120.1(4)S(1) Ru(1) C;2: 171.84(7) C(7) 0;12) C(1:) 118.2(4)S(1) Ru(1) 0(3 85.61(8) S(2) C(13) C(14) 122.0(3)0(t) Ru(1) 0(3) 86.8(1) S(2) C(13) C(18) 117.0(3)Ru(1) S(1) 0(1) 109.4(1) C(14) C(13) C(18) 121.0(3)Ru(1) S(1) C(1) 115.6(1) C(13) 0(14) C(15) 118.4(4)Ru(1) 5(1) C(7) 118.6(1) C(14) C(15) C(16) 120.0(4)0(1) 5(1) C(1) 105.6(2) C(15) C(16) C(17) 121.0(4)0(1) S(1) C(7) 106.4(2) C(16) C(17) C(18) 120.5(4)C(1) S(1) C(7) 100.0(2) C(13) C(18) C(17) 119.1(4)0(2) 5(2) C(13) 105.2(2) 5(2) C(19) C(20) 117.2(3)0(2) S(2) 0(19) 103.3(2) S(2) C(19) C(24) 121.2(3)C(13) 5(2) C(19) 98.5(2) C(20) C(19) 0(24) 121.6(4)Ru(1) 0(2) 5(2) 119.6(1) C(19) C(20) C(21) 119.2(5)Ru(1) 0(3) C(25) 125.3(3) C(20) C(21) C(22) 119.9(5)5(1) 0(1) C(2) 121.8(3) C(21) 0(22) C(23) 120.0(5)C(1) ,,g , 116.6(3) C(22) 0(23) C(24) 121.0(6)C(2) C(1) C(6 121.6(4) 0(19) C;24) 0(23) 118.2(5)243Appendix D^ RuCI 3 (Ph2S011(Me0H)D-6(e) ORTEP Diagram of RuC13(Ph1S0)1(Me0H)244Appendix D^ Trans-RuC12(BMSE)2D-7 Crystal Data and Results for truns-RuC12(BMSE)2D-7(a) Experimental DetailsA. Crystal DataEmpirical Formula^ C 8 H 22 Cl 2 0 5 RuS 4Formula Weight 498.47Crystal Color, Habit^ yellow, prismCrystal Dimensions (mm) 0.200 X 0.200 X 0.500Crystal System^ triclinicNo.^Reflections Used fcr^UnitCell^Determination (29^range) 25^( 57.5^-^59.2°)Omega Scan^Peak widthat Half-height 0.37Lattice^Parameters:a 8.863^(1)Ab - 14.462^(3)Ac - 7.543^(1)ACI^.0 103.39^(1)°113.31^(1)°y ■ 77.23^(1)°V - 854.6^(2)A3Space Group PI^(41)Z value 2Dcalm 1.937 g/cm3000 50441(M o ra ) 16.97 cm-1B. Intensity MeasurementsDiffractometer^ Rigaku AFC6SRadiation^ Mona (X^0.71069 A)Temperature 21°CTake-off Angle^ 6.0'245Appendix D^Trans-RuCk(BMSE)1Experimental Details (cont.)Detector Aperture^ 6.0 mm horizontal6.0 mm verticalCrystal to Detector Distance^285 mmScan Type^ w-28Scan Rate 32.0°/min (in omega)(8 rescanS)Scan Width^ (1.52 + 0.35 tane)°2emax 90.0°No. of Reflections Measured^Total:^:4660Unique:^14063 (R,n, ■ .026)Corrections^ Lorentz-polarizationAbsorption(trans. factors:^0.82 - 1.00)Decay^decline)C.^Structure Solution and RefinementStructure Solution^ Patterson MethodRefinement^ Full-matrix least-squaresFunction Minimized^ E w (IFol - IFc1) 2Least-squares Weights 4Fo 2 /a 2 (Fo 2 )p-factorAnomalous DispersionNo.^Observations^(I>3.00a(I))0.03All non-hydrogen atoms10461No. Variables 358Reflection/Parameter Ratio 29.22Residuals:^R;^Rw 0.026;^0.034Goodness^of^Fit^Indicator 1.33Max Shift/Error^in Final^Cycle 0.55Maximum Peak^in Final Diff.^Map 0.66 e-/A3Minimum Peak^in^Final^Diff.^Map -0.64^e-/A3246Appendix D^Trans-RuCh(BMSE),.1 *D-7(b) Final Atomic Coordinates (fractional) and Beq (A-)atom B ( eqRu(1) 0.2500 0.2500 0.2500 1.193(3)Ru(2) 0.7497(1) 0.75001(7) 0.7498(1) 1.316(3)C1(1) 0.2774(2) 0.3748(1) 0.1076(3) 2.24(6)C1(2) 0.2229(2) 0.1254(1) 0.3939(3) 2.09(6)C1(3) 0.7583(2) 0.8261(2) 1.0724(3) 2.32(6)C1(4) 0.7406(3) 0.6740(2) 0.4292(3) 2.43(6)5(1) -0.0045(2) 0.2411;1) -0.0013(3) 1.61(5)5(2) 0.3606(2) 0.1372(1) 0.0461(3) 1.59(5)S(3) 0.5078(2) 0.2580(1) 0.4973(2) 1.47(4)S(4) 0.1428(2) 0.3640(1) 0.4582(3) 1.69(5)S(5) 0.9807(2) 0.6386(1) 0.8704(3) 1.75(5)S(6) 0.5928(2) 0.6410(2) 0.7505(3) 2.07(6)5(7) 0.5214(2) 0.8612(1) 0.6291(3) 1.84(5)S(8) 0.9040(2) 0.8587(1) 0.7462(3) 1.68(5)0(1) -0.1145(6) 0.3313(3) -0.0605(7) 2.1(1)0(2) 0.4579(9) 0.1692(4) -0.046(1) 2.7(1)0(3) 0.6198(7) 0.1693(4) 0.5497(8) 2.7(2)0(4) 0.0364(8) 0.3389(5) 0.539(1) 2.8(2)0(5) 1.1154(7) 0.6199(5) 0.794(1) 2.9(1)0(6) 0.4929(8) 0.5907(5) 0.5627(8) 3.8(2)0(7) 0.3958(7) 0.8888(4) 0.722(1) 2.5(1)0(8) 1.0019(8) 0.9133(4) 0.9335(8) 3.2(2)0(9) -0.0250(9) -0.0083(5) 0.369(1) 6.0(3)0(10) 0.5721(8) 0.4895(6) 0.139(1) 5.0(2)247Appendix D^ Trans-RuCk(BMSE),Final Atomic Coordinates (fractional) and Batom(cont.)B(eq)C(1) 0.034(1) 0.1729(5) -0.212(1) 2.1(1)C(2) 0.182(1) 0.0924(5) -0.149(1) 2.7(2)C(3) 0.4520(9) 0.3248(5) 0.7072(8) 1.8(1)C(4) 0.3231(8) 0.4094(3) 0.6513(9) 2.0(2)C(5) -0.130(1) 0.1608(5) 0.021(1) 2.2(1)C(6) 0.4730(8) 0.0296(5) 0.143(1) 2.5(2)C(7) 0.62899) 0.3253(5) 0.464(1) 2.4(2)C(8) 0.034(1; 0.4691(6) 0.364(1) 3.8(3)C(9) 0.90127) 0.5312(4) 0.8428(8) 1.8(1)C(12) 0.7S2_ 0.5544(6) 0.9021) 2.3(2)C(11) 0.610(1) 0.9699(5) 0.664(1) 3.0(2)C(12) 0.760(1) 0.9430(6) 0.604(1) 2.5(2)C(13) 1.088(1) 0.6582(6) 1.132(1) 3.3(3)C(14) 0.4666(8) 0.6839(5) 0.894(1) 2.6(2)C(15) 0.418(1) 0.8366(6) 0.373(1) 3.3(2)C(16) 1.036(1) 0.8132(6) 0.609(1) 3.4(3)248Appendix D^Trans-RuC11( BN1SE),D-7(c) Bond Lengths (it) with Estimated Standard Deviationsatom atom distance atCM atom distanceRu(1) C1(1) 2.402(2) 5(3) C(7) 1.717(7)Ru(1) C1(2) 2.405(2) 5(4) 0(4) 1.453(6)Ru(1) 5(1) 2.308(2) 5(4) C(4) 1.812(6)Ru(1) S(2) 2.305(2) 5(4) C(8) 1.748(8)Ru(1) 5(3) 2.315(2) 5(5) 0(5) 1.468(6)Ru(1) 5(4) 2.319(2) 5(5) C(9) 1.781(6)Ru(2) C1(3) 2.406(2) S(5) C(13) 1.805(8)Ru(2) C1(4) 2.391(2) 5(6) 0(6) 1.461(5)Ru(2) 6(6) 2.315(2) 5(6) C(10) 1.863(8)Ru(2) S(6) 2.324(2) 5(6) C(14) 1.773(6)Ru(2) 5(7) 2.300(2) S(7) 0(7) 1.479(6)Ru(2) 5(8) 2.312(2) 5(7) C(11) 1.827(7)S(1) 0(1) 1.489(5) 5(7) 0(15) 1.766(8)5(1) C(1) 1.780(7) 5(8) 0(8) 1.480(6)5(1) C(5) 1.855(7) 5(8) C(12) 1.758(9)S(2) 0(2) 1.495(7) S(8) 0(16) 1.788(8)5(2) C(2) 1.808(7) C(1) C(2) 1.54(1)5(2) C(6) 1.791(6) C(3) C(4) 1.490(9)5(3) 0(3) 1.466(6) C(9) C(10) 1.503(9)S(3) C(3) 1.840(6) C(11) C(12) 1.52(1)249Appendix D^ Trans-RuCk(BNISE)1D-7(d) Bond Angles (°) with Estimated Standard Deviationsatom atom atom angle atom atom atom angleC1(1) Ru(1) C1(2) 179.76(9) 5(5) Ru(2) S(8) 93.71(7)C1(1) Ru(1) S(1) 86.55(7) S(6) Ru(2) 5(7) 93.70(7)C1(1) Ru(1) S(2) 89.49(7) 5(6) Ru(2) S(8) 179.4(1)C1(1) Ru(1) 5(3) 92.90(7) 5(7) Ru(2) S(8) 85.89(7)C1(1) Ru(1) S(4) 90.33(7) Ru(1) 5(1) 0(1) 119.4(2)C1(2) Ru(1) 5(1) 93.60(7) Ru(1) S(1) C(1) 107.2(2)C1;2) Ru(1) S(2) 90.70(7) Ru(1) 5(1) C(5) :14.3(2)C1(2) Ru(1) 5(3) 86.94(7 0(1) 5(1) C(1) 107.0(3)C1(2) Ru(1) S(4) 89.48(6) 0(1) 5(1) C(5) 108.5(3)5(1) Ru(1) 5(2) 86.76(7) C(1) 5(1) C(5) 98.1(3)5(1) Ru(1) 5(3) 178.81(9) Ru(1) 5(2) 0(2) 118.4(3)5(1) Ru(1) 5(4) 94.10(7) Ru(1) 5(2) C(2) 104.1(2)5(2) Ru(1) 5(3) 92.18(6) Ru(1) 5(2) C(6) 115.0(2)5(2) Ru(1) 5(4) 179.11(9) 0(2) 5(2) C(2) 107.4(4)5(3) Ru(1) S(4) 86.96(7) 0(2) 5(2) C(6) 108.8(4)C1(3) Ru(2) C1(4) 179.8(1) C(2) 5(2) C(6) 101.2(3)C1(3) Ru(2) 5(5) 92.62(7) Ru(1) 5(3) 0(3) 119.8(2)C1(3) Ru(2) 5(6) 89.64(7) Ru(1) 5(3) C(3) 102.0(2)C1(3) Ru(2) 5(7) 87.56(7) Ru(1) 5(3) C(7) 114.3(3)C1(3) Ru(2) S(8) 90.73(7) 0(3) S(3) C(3) 109.8(3)C1(4) Ru(2) S(5) 87.37(7) 0(3) S(3) C(7) 103.9(3)C1(4) Ru(2) S(6) 90.14(8) C(3) 5(3) C(7) 106.3(3)C1(4) Ru(2) S(7) 92.44(7) Ru(1) 5(4) 0(4) 120.4(3)C1(4) Ru(2) S(8) 89.50(7) Ru(1) 5(4) C(4) 104.6(2)5(5) Ru(2) S(6) 86.70(7) Ru(1) 5(4) C(8) 114.4(3)5(5) Ru(2) S(7) 179.56(9) 0(4) S(4) C(4) 110.8(4)250Appendix D^ Trans-RuCHBNISEllBond Angles (°) with Estimated Standard Deviations (cont.)atom atom atom angle atom atom atom angle0(4) S(4) C(8)^- 104.4(4) 5(1) C(1) C(2) 109.2(5)C(4) 5(4) C(8) 100.6(4) 5(2) C(2) C(1) 112.5(4)Ru(2) 5(5) 0(5) 119.8(3) S(3) C(3) C(4) 111.0(4)Ru(2) 5(5) C(9) 105.4(2) 5(4) C(4) C(3) 107.1(4)Ru(2) S(5) C(13) 115.7(3) S(5) C(9) C(10) 109.9(4)0(5) 5(5) C(9) 111.3(3) S(6) C(10) C(9) 109.1(5)0(5) S(5) C(13) 103.4(4) S(7) C(11) C(12) 108.9(5)C(9) S(5) C;13; 99.6(3) 5(8) C(12) 0(11) 108.5(5)Ru(2) S(6) 0(6) 118.3(3)Ru(2) 5(6) 0(10) 102.7(3)Ru(2) S(6) 0(14) 115.5(3)0(6) 5(6) C(10) 110.8(4)0(6) S(6) C(14) 107.9(4)C(10) S(6) C(14) 99.9(3)Ru(2) 5(7) 0(7) 119.3(3)Ru(2) S(7) C(11) 103.9(2)Ru(2) 5(7) C(15) 113.9(2)0(7) S(7) C(11) 106.2(4)0(7) S(7) C(15) 108.5(4)C(11) S(7) C(15) 103.5(4)Ru(2) S(8) 0(8) 119.1(3)Ru(2) S(8) C(12) 105.6(3)Ru(2) S(8) C(16) 115.1(3)0(8) 5(8) C(12) -.7.1(4)0(8) 3(8) C(16) 107.3(4)C(12) 5(8) C(16) 100.6(4)251Appendix D^ Cis-RuC12(BESE)2D-8 Crystal Data and Results for cis-RuC12(BESE)2D-8(a) Experimental DetailsFormula Weight^ 568.61Crystal Color, Habit^ pale, prismCrystal Dimensions (mm) 0.150 X 0.250 X 0.300Crystal System^ triclinicNo. Reflections Used for UnitCell Determination (29 range)Omega Scan Peak Widthat Half-heightLattice Parameters:Space GroupZ valueDcalcF000PihOlCa)250.38(^48.4^- 54.8°)a . 14.858 (2)Ab ■ 16.732 (3)Ac ■ 10.609 (2)Aa ■ 105.14 (2)°0 . 93.34 (2)*y = 115.91 (1)*V . 2244^(2)A3PI (#2)41.683 g/cm 31168-113.03 caB. Intensity MeasurementsDiffractometer^ Rigaku J:FC6SRadiation MOKa (A ■ 0.71069 A)Temperature^ 21°CTake-off Angle 6.0*252Appendix D^ Cis-RuC12(BESE)2Experimental Details (cont.)Crystal to Detector DistanceScan TypeScan RateScan Width2emax285 mmto-2032.0'/win (in omega)(8 rescans)(1.37 4. 0.35 tame)"60.0'No. of Reflections Measured^Total: 13546Unique: 13078 (Rint - .018)Corrections Lorentz-polarizationAbsorption(trans. factors:^0.85 - 1.00)Decay ( -2.60% decline)Secondary Extinction(coefficient:^0.70738E-07)C. Structure Solution and RefinementStructure SolutionRefinementFunction MinimizedLeast-squares Weightsp-factorAnomalous DispersionNo. Observations (I>3.00a(I))No. VariablesReflection/Parameter RatioResiduals: T.; RwGoodness of Fit IndicatorMax Shift/Error in Final CycleMaximum Peak in Final Diff. MapMinimum Peak in Final Diff. MapPatterson MethodFull-matrix least-squaresZ w (1Fol - IFc1) 24Fo 2/a 2 (Fo 2 )0.02All non-hydrogen atoms895247218.970.026; 0.0321.480.030.58 e'/A!-0.38 e-/A'Appendix D Cis-RuC12(BESE)2D-8(b) Final Atomic Coordinates (fractional) and B^(A2)*eqatom^x^ z Beq OCC .Ru(1) 0.26705(2) 0.49342(1) 0.66806(2) 2.590(6)Ru(2) 0.18158(1) -0.04474(1) 0.30596(2) 2.191(6)C1(1) 0.22263(6) 0.36604(5) 0.76011(7) 3.63(2)C1(2) 0.32372(6) 0.40987(5) 0.49212(7) 3.71(2)C1(3) 0.09593(5) -0.05158(5) 0.49398(6) 3.05(2)C1(4) 0.09841(5) -0.21583(4) 0.23482(7) 3.24(2)S(1) 0.31673(5) 0.61661(5) 0.58872(7) 3.24(2)S(2) 0.42649(5) 0.57031(5) 0.80321(8) 3.38(2)S(3) 0.20628(5) 0.56669(5) 0.82354(7) 3.07(2)S(4) 0.10658(5) 0.41897(4) 0.53692(7) 2.99(2)S(5) 0.26680(5) -0.04067(5) 0.13459(6) 2.75(2)S(6) 0.31842(5) -0.04114(4) 0.42659(6) 2.54(2)S(7) 0.25159(5) 0.11388(4) 0.36639(6) 2.82(2)S(8) 0.04660(5) -0.05159(5) 0.17807(6) 2.87(2)0(1) 0.2504(2) 0.6611(1) 0.5832(2) 4.08(7)o(2) 0.4342(2) 0.6128(2) 0.9467(2) 4.56(7)0(3) 0.0925(2) 0.4529(1) 0.4256(2) 3.91(7)0(4) 0.2628(2) 0.6693(1) 0.8818(2) 4.14(7)0(5)^, 0.2871(2) 0.0342(1) 0.0739(2) 3.73(7)0(6) 0.3990(1) 0.0479(1) 0.5204(2) 3.34(6)0(7) 0.3592(1) 0.1690(1) 0.3596(2) 3.89(7)0(8) 0.0405(2) -0.0803(1) 0.0320(2) 3.63(6)0(9) 0.0251(3) 0.3428(3) 0.0653(4) 6.0(2) 0.660(9B) 0.120(1) 0.409(1) 0.176(1) 13.0(8) 0.34254Appendix D^ Cis-RuC12(BESE)2Final Atomic Coordinates (fractional) and B (A2)* (cont.)eqatom B eg OCC.0(10) 0.4463(5) 0.8131(5) 0.0581(7) 10.7(3) 0.620(10B) 0.5292(7) 0.8907(7) 0.019(1) 8.0(4) 0.38C(1) 0.4367(2) 0.7052(2) 0.6974(3) 4.3(1)C(2) 0.5011(2) 0.6615(2) 0.7343(3) 4.4(1)C(3) 0.0809(2) 0.5371(2) 0.7400(3) 3.5(1)C(4) 0.0260(2) 0.4367(2) 0.6508(3) 3.6(1)C(5) 0.3529(3) 0.5962(2) 0.4282(3) 4.6(1)C(6) 0.3819(3) 0.6784(3) 0.3747(4) 6.1(2)C(7) 0.4949(3) 0.5035(2) 0.7879(4) 4.7(1)C(8) 0.6028(3) 0.5594(3) 0.8675(4) 6.1(2)C(9) 0.1790(2) 05215(2) 0.9613(3) 4.0(1)C(10) 0.1528(3) 0.5818(3) 1.0696(4) 5.6(1)C(11) 0.0501(2) 0.2934(2) 0.4729(3) 4.1(1)C(12) -0.0471(2) 0.2517(2) 0.3712(4) 4.8(1)C(13) 0.3888(2) -0.0274(2) 0.2030(3) 3.20(8)C(14) 0.3765(2) -0.0836(2) 0.2985(3) 3.08(8)C(15) 0.1745(2) 0.1340(2) 0.2530(3) 3.7(1)C(16) 0.0617(2) 0.0661(2) 0.2338(3) 3.6(1)C(17) 0.2175(2) -0.1489(2) -0.0011(3) 3.42(9)C(18) 0.2726(3) -0.1356(2) -0.1161(3) 4.3(1)C(19) 0.2817(2) -0.1275(2) 0.5107(3) 3.4(1)C(20) 0.3714(2) -0.1160(2) 0.6007(3) 3.7(1)C(21) 0.2335(2) 0.1733(2) 0.5232(3) 3.6(1)C(22) 0.3081(3) 0.1878(3) 0.6379(3) 5.5(1)C(23) -0.0771(2) -0.1184(2) 0.2095(3) 3.9(1)255Appendix D^ Cis-RuC12(BESE)2Final Atomic Coordinates (fractional) and B (A2)* (cont.)eqatom^x^ Y^ z^Beg^O CC.C(24) -0.1608(3) -0.1237(3) 0.1146(4) 6.8(2)C(25) 0.1098(3) 0.3312(3) 0.1041(4) 6.5(2)C(26) 0.5414(4) 0.8392(3) 0.1039(5) 7.3(2)*13eq . (8/3)7t2 Zru. .a.*a.*(a..a.)13 1^)^1^3256Appendix D Cis-RuC12(BESE)2D-8(c) Bond Lengths (A) with Estimated Standard Deviationsatom atom distance atom atom distanceRu(1) C1(1) 2.4217(8) S(5) C(17) 1.802(3)Ru(1) C1(2) 2.4486(8) S(6) 0(6) 1.473(2)Ru(1) S(1) 2.2697(8) S(6) C(14) 1.806(3)Ru(1) S(2) 2.302(1) S(6) C(19) 1.796(3)Ru(1) S(3) 2.2636(8) S(7) 0(7) 1.473(2)Ru(1) 5(4) 2.299(1) 5(7) C(15) 1.807(3)Ru(2) C1(3) 2.4287(8) S(7) C(21) 1.802(3)Ru(2) C1(4) 2.4419(9) S(8) 0(8) 1.482(2)Ru(2) S(5) 2.2738(8) S(8) C(16) 1.807(3)Ru(2) 5(6) 2.3076(8) S(8) C(23) 1.791(3)Ru(2) 5(7) 2.2712(8) 0(9) C(25) 1.409(6)Ru(2) 5(8) 2.2973(8) 0(98) C(25) 1.26(1)S(1) 0(1) 1.479(2) 0(10) C(26) 1.302(7)S(1) C(1) 1.806(3) 0(108) C(26) 1.45(1)5(1) C(5) 1.808(3) C(1) C(2) 1.524(5)S(2) 0(2) 1.476(2) C(3) C(4) 1.505(4)5(2) C(2) 1.814(3) C(5) C(6) 1.523(5)5(2) C(7) 1.796(3) C(7) C(8) 1.509(5)S(3) 0(4) 1.470(2) C(9) C(10) 1.509(4)S(3) C(3) 1.810(3) C(11) C(12) 1.510(5)S(3) C(9) 1.803(3) C(13) C(14) 1.522(4)3(4) 0(3) 1.478(2) C(15) C(16) 1.522(4)5(4) C(4) 1.809(3) C(17) C(18) 1.519(4)S(4) C(11) 1.796(3) C(19) C(20) 1.501(4)5(5) 0(5) 1.480(2) C(21) C(22) 1.492(5)5(5) C(13) 1.808(3) C(23) C(24) 1.509(5)257Appendix D^ Cis-RuCl2(BESE)2D-8(d) Bond Angles (°) with Estimated Standard Deviationsatom atom atom angle atom atom atom angleC1(1) Ru(1) C1(2) 88.26(3) 5(5) Ru(2) 5(8) 91.09(3)C1(1) Ru(1) S(1) 177.05(3) S(6) Ru(2) S(7) 93.73(3)C1(1) Ru(1) S(2) 89.36(3) 5(6) Ru(2) 5(8) 177.65(2)C1(1) Ru(1) 5(3) 91.82(3) 5(7) Ru(2) S(8) 87.42(3)C1(1) Ru(1) S(4) 90.87(3) Ru(1) 5(1) 0(1) 119.52(9)C1(2) Ru(1) S(1) 91.83(3) Ru(1) 5(1) C(1) 105.0(1)C1(2) Ru(1) S(2) 91.72(3) Ru(1) 5(1) C(5) 114.4(1)C1(2) Ru(1) 5(3) 176.92(3) 0(1) S(1) C(1) 107.3(1)C1(2) Ru(1) 5(4) 89.73(3) 0(1) 5(1) C(5) 106.9(1)S(1) Ru(1) 5(2) 87.69(3) C(1) 5(1) C(5) 102.2(2)5(1) Ru(1) 5(3) 88.25(3) Ru(1) 5(2) 0(2) 117.5(1)S(1) Ru(1) S(4) 92.08(3) Ru(1) 5(2) C(2) 104.2(1)5(2) Ru(1) 5(3) 91.36(3) Ru(1) 5(2) C(7) 114.8(1)S(2) Ru(1) 5(4) 178.54(3) 0(2) 5(2) C(2) 109.3(1)S(3) Ru(1) 5(4) 87.19(3) 0(2) S(2) C(7) 107.5(2)C1(3) Ru(2) C1(4) 87.13(3) C(2) 5(2) C(7) 102.3(2)C1(3) Ru(2) S(5) 177.17(2) Ru(1) 5(3) 0(4) 118.88(9)C1(3) Ru(2) S(6) 90.42(3) Ru(1) S(3) C(3) 104.8(1)C1(3) Ru(2) S(7) 92.67(3) Ru(1) 5(3) C(9) 115.3(1)C1(3) Ru(2) S(8) 91.58(3) 0(4) 5(3) C(3) 107.4(1)C1(4) Ru(2) S(5) 91.94(3) 0(4) 5(3) C(9) 106.3(1)C1(4) Ru(2) 5(6) 89.24(3) C(3) 5(3) C(9) 102.7(1)C1(4) Ru(2) 5(7) 177.03(3) Ru(1) 5(4) 0(3) 117.20(9)C1(4) Ru(2) S(8) 89.62(3) Ru(1) 5(4) C(4) 104.4(1)5(5) Ru(2) 5(6) 86.89(3) Ru(1) S(4) C(11) 115.4(1)5(5) Ru(2) 5(7) 88.39(3) 0(3) 5(4) C(4) 108.3(1)258Appendix D^Cis-RuC12(BESE)2D-8(e) Bond Angles ('') with Estimated Standard Deviationsatom atom atom angle atom atom atom angle0(3) S(4) C(11) 107.8(1) S(1) C(1) C(2) 111.0(2)C(4) S(4) C(11) 102.5(1) S(2) C(2) C(1) 109.1(2)Ru(2) S(5) 0(5) 118.81(8) S(3) C(3) C(4) 111.3(2)Ru(2) S(5) C(13) 104.72(9) S(4) C(4) C(3) 108.1(2)Ru(2) S(5) C(17) 115.8(1) S(1) C(5) C(6) 113.3(2)0(5) S(5) C(13) 107.6(1) S(2) C(7) C(8) 113.1(3)0(5) S(5) C(17) 106.6(1) S(3) C(9) C(10) 112.1(2)C(13) S(5) C(17) 101.7(1) S(4) C(11) C(12) 111.7(2)Ru(2) S(6) 0(6) 120.43(8) S(5) C(13) C(14) 110.8(2)Ru(2) S(6) C(14) 103.0(1) S(6) C(14) C(13) 106.5(2)Ru(2) S(6) C(19) 113.4(1) S(7) C(15) C(16) 111.0(2)0(6) S(6) C(14) 107.7(1) S(8) C(16) C(15) 107.8(2)0(6) S(6) C(19) 107.8(1) S(5) C(17) C(18) 111.3(2)C(14) S(6) C(19) 102.8(1) S(6) C(19) C(20) 112.0(2)Ru(2) S(7) 0(7) 119.17(8) S(7) C(21) C(22) 111.9(2)Ru(2) S(7) C(15) 104.1(1) S(8) C(23) C(24) 111.7(2)Ru(2) S(7) C(21) 117.3(1)0(7) S(7) C(15) 107.6(1)0(7) S(7) C(21) 106.6(1)C(15) S(7) C(21) 100.0(1)Ru(2) S(8) 0(8) 116.28(8)Ru(2) S(8) C(16) 104.8(1)Ru(2) S(8) C(23) 115.9(1)0(8) S(8) C(16) 108.8(1)0(8) S(8) C(23) 107.9(1)C(16) 5(8) C(23) 101.9(1)259Appendix D^ Cis-RuC12(BESE)2D-8(f) Stereoviews for cis-RuCl2 (BESE)2 and the Unit Cell showing 50%Probability Thermal Ellipsoids260Appendix D^ Trans-RuC12(BPSE)2D-9 Crystal Data and Results fortrans-RuC12(3PSE)2D-9(a) Experimental DetailsA. Crystal DataEmpirical Formula^ C 16 H 36 C1 2 0 4 RuS 4Formula Weight 592.67Crystal Color, Habit^ yellow, prismCrystal Dimensions (mm) 0.080 X 0.280 X 0.370Crystal System^ orthorhombicNo. Reflections Used for UnitCell Determination (28 range)^25 ( 26.8 -^42.0°)Omega Scan Peak Widthat Half-height^ 0.37Lattice Parameters:a^14.894 (1)Ab -^7.501 (1)Ac 21.911 (2)AV^2448.0 (9)A3Space Group^ Aba2 (041)Z value 41.608 g/cm 3D calc0004J(MoRa)122411.95 cmB. Intensity MeasurementsDiffractometer^ Rigaku AFC6SRadiation MoRa (X^0.71069 A)Detector Aperture^ 6.0 mm horizontal6.0 mm verticalCrystal to Detector Distance^285 mm261Appendix D^ Trans-RuCl2(BPSE)2Experimental Details (cont.)Temperature^ 21°CTake-off Angle 6.0°Scan Type^ w-28Scan Rate 16.0°/min (in omega)(8 rescans)Scan Width^ (1.05 + 0.35 tame)*629max 9.9°No. of Reflections Measured^Total: 2958Corrections^ Lorentz-polarizationAbsorption(trans. factors:^0.86 - 1.00)C. Structure Solution and RefinementStructure SolutionRefinementFunction MinimizedLeast-squares WeightsPatterson MethodFull-matrix least-squaresw (IFol - IFc1) 22^2,, 2,4Fo /a kro /p-factorAnomalous^DispersionNo.^Observations^(I>3.00a(I))No.^Variables'Reflection/Parameter RatioResiduals:^R;^RwGoodness of Fit IndicatorMax Shift/Error in Final Cycle0.01All non-hydrogen atoms159413112.170.029;^0.0301.750.53Maximum Peak in Final Diff. MapMinimum Peak in Final Diff. Map0.51 e-/A;-0.43 e-/A°262Appendix D^ Trans-RuCb(BPSE)2D-9(b) Final Atomic Coordinates (fractional) and B (A2)*eqatom X y z B eq °CC.Ru(1) 1/2 1/2 1/2 2.69(1)C1(1) 0.57014(6) 0.7892(1) 0.5006(2) 4.00(4)S(1) 0.6029(2) 0.4085(4) 0.5730(2) 3.4(1)5(2) 0.6032(2) 0.4109(5) 0.4282(2) 3.7(2)0(1) 0.6358(8) 0.539(1) 0.6154(6) 8.5(5)0(2) 0.6504(9) 0.543(2) 0.3905(6) 8.0(5)C(1) 0.7025(3) 0.3612(7) 0.5340(3) 3.9(2)C(2) 0.6794(3) 0.2640(7) 0.4771(3) 4.0(2)C(3) 0.567(1) 0.230(2) 0.6177(8) 6.4(7)C(4) 0.6475(7) 0.175(2) 0.6658(6) 5.6(5)C(5) 0.622(1) 0.044(3) 0.713(1) 13(1)C(6) 0.5762(8) 0.220(2) 0.3822(7) 4.8(5)C(7) 0.643(1) 0.167(3) 0.3376(8) 10(1)C(8) 0.633(3) 0.008(5) 0.311(2) 11(2) 0.64C(8A) 0.617(2) 0.209(6) 0.285(2) 12(2) 0.36*8eq(8/3)Y12Ittl. .a.*a.*(a..a.)13i^3263Appendix D^ Trans-RuC12(BPSE)1D-9(c) Bond Lengths (A) with Estimated Standard Deviationsatom atom distance atom atom distanceRu(1) C1(1) 2.4077(8) 5(2) C(6) 1.80(1)Ru(1) S(1) 2.319(3) C(1) C(2) 1.484(7)Ru(1) S(2) 2.300(4) C(3) C(4) 1.65(2)S(1) 0(1) 1.44(1) C(4) C(5) 1.47(2)S(1) C(1) 1.747(6) C(6) C(7) 1.45(2)5(1) C(3) 1.74(1) C(7) C(8) 1.33(3)S(2) 0(2) 1.47(1) C(7) C(8A) 1.25(5)5(2) C(2) 1.911(6)264Appendix D^Trans-RuC12(BPSE)2D-9(d) Bond Angles (*) with Estimated Standard Deviationsatom atom^atom^angle atom^atom^atom angleC1(1) Bu(l)^C1(1)'^179.3(2) C(1) S(1)^C(3) 112.1(6)C1(1) Ru(1)^S(1)^88.6(1) Rut 1)^S(2)^0(2) 120.6(5)C1(1) Ru(1)^5(1)'^90.9(1) Ru(1)^S(2)^C(2) 100.4(2)C1(1) Ru(1)^5(2)^88.6(1) Ru(1)^S(2)^C(6) 117.8(4)C1(1) Rut 1)^5(2)'^91.8(1) 0(2)^S(2)^C(2) 114.8(6)S(1) Ru(1)^S(1)'^92.8(2) 0(2)^S(2)^C(6) 109.2(8)S(1) Ru(1)^S(2)^86.78(3) C(2) S(2)^C(6) 89.3(6)S(1) Ru(1)^5(2)'^179.4(2) S(1)^C(1)^C(2) 108.3(3)S(2) Ru(1)^5(2)'^93.6(2) S(2)^C(2)^C(1) 109.0(4)Ru(1) S(1)^0(1)^118.1(5) S(1) C(3)^C(4) 109(1)Ru(1) S(1)^C(1)^106.5(2) C(3)^C(4)^C(5) 115(1)Ru(1) S(1)^C(3)^114.5(6) S(2) C(6)^C(7) 116.2(9)0(1) S(1)^C(1)^99.5(6) C(6)^C(7)^C(8) 118(2)0(1) S(1)^C(3)^105(1) C(6)^C(7)^C(8A) 109(3)*Here and elsewhere primes^refer to symmetry operation: 1-x,^1-y,^z.265Appendix D^ Trans-RuC12(BPSE)1D-9(e) ORTEP Plot for trans-RuC12(BPSE), Showing 50% Probability PlotsCs266Appendix D^ Cis-RuC11(B M SP)1D-10 Crystal Data and Results for cis-RuCI1(BN1SP),D-10(a) Experimental DetailsA. Crystal DataEmpirical Formula^ C1024C1204RuS4Formula Weight 508.51Crystal Color, Habit^ orange-yellow, prismCrystal Dimensions (mm) 0.250 X 0.350 X 0.450Crystal System^ orthorncmbicNo. Reflections Used for UnitCell Determinaticn (28 range)^25 ( 54.3 -^54.90Omega Scan Peak Widthat Half-height^ 0.36Lattice Parameters:a^15.257 (3)Ab -^18.138 (2)Ac -^13.395 (2)AV -^3706.7 (7)A3Space Group^ Pcab (#61)Z value 81.822 g/cm 3calc000^ 2064(MoRm)^ 15.63 cmB. Intensity MeasurementsDiffractometer^ Rigaku AFC6SRadiation MoRm (X ■ 0.7069 A)Temperature^ 21'CTake-off Angle 6.0°Appendix D^ Cis-RuC12(BMSP)2Experimental Details (cont.)Detector ApertureCrystal to Detector DistanceScan Type6.0 mm horizontal6.0 mm vertical285 mmw-28Scan Rate^ 32.0°/min (in omega)(8 rescans)Scan Width^ (1.47 + 0.35 tan8)°728max 0.0°No. of Reflections Measured^Total: 8907Corrections^ Lorentz-polarizationAbsorption(trans. factors:^0.83- 1.00)C. Structure Solution and RefinementStructure Solution^ Patterson MethodRefinement^ Full-matrix least-squaresFunction Minimized^ I w (IFoi - IFc1) 2Least-squares Weights 4Fo 2/c 2 (Fo 2 )p-factorAnomalous DispersionNo.^Observations^(I>3.00a(I))No.^%ariablesReflection/Parameter RatioResiduals:^R;Goodness of^Fit IndicatorMax Shift/Error^in Final^Cycle0.01All non-hydrogen atoms569419029.970.031;^0.0372.220.19Maximum Peak in Final Diff. Map^2.26 e -/A!Minimum Peak in Final Diff. Map^-1.38 e-/A'268Appendix D^ Cis-Rua2(BMSP)2D-10(b) Final Atomic Coordinates (fractional) and B (A2)*eciatom x Y z BegRu(1) 0.04432(1) 0.12609(1) 0.22154(1) 1.452(6)CI (i ) 0.05190(4) 0.10339(4) 0.04224(4) 2.44(2)C1(2) -0.01671(5) 0.24622(3) 0.17954(5) 2.63(2)S(1) 0.03357(4) 0.14939(4) 0.38767(4) 2.15(2)S(2) 0.18884(4) 0.16889(4) 0.19906(5) 2.11(2)S(3) 0.10446(4) 0.01496(3) 0.25807(4) 1.87(2)5(4) -0.10313(4) 0.08860(3) 0.22814(5) 1.99(2)0(1) -0.0059(1) 0.0896(1) 0.4473(1) 3.6(1)0(2) 0.2474(1) 0.1207(1) 0.1408(2) 3.17(8)0(3) 0.1804(1) 0.0191(1) 0.3267(1) 2.73(8)0(4) -0.1650(1) 0.1397(1) 0.2776(1) 2.95(8)C(1) 0.1351(2) 0.1723(2) 0.4488(2) 3.4(1)C(2) 0.1925(2) 0.2265(2) 0.3923(2) 4.2(2)C(3) 0.2477(2) 0.1901(2) 0.3115(2) 3.4(1)C(4) -0.0272(2) 0.2306(2) 0.4153(2) 3.6(1)C(5) 0.1923(2) 0.2573(2) 0.1415(2) 3.7(1)0(6) 0.0316(2) -0.0517(1) 0.3123(2) 2.7(1)C(7) -0.0564(2) -0.0596(2) 0.2597(2) 3.0(1)C(8) -0.1217(2) 0.0013(2) 0.2865(2) 2.8(1)C(9) 0.1399(2) -0.0348(2) 0.1509(2) 3.0(1)C(10) -0.1449(2) 0.0710(2) 0.1069(2) 3.2(1)*8eg . (8/3)n 2 IZU..a.*a.*(a..a.)13 1^)^1^)269Appendix D^ Cis-RuC12(BMS13)2D-10(c) Bond Lengths (A) with Estimated Standard Deviationsatom atom distance atom atom distanceRu(1) C1(1) 2.4395(7) 5(2) C(5) 1.780(3)Ru(1) C1(2) 2.4354(7) S(3) 0(3) 1.480(2)Ru(1) S(1) 2.2710(6) 5(3) C(6) 1.796(3)Ru(1) 5(2) 2.3569(7) 5(3) C(9) 1.780(3)Ru(1) 5(3) 2.2682(6) S(4) 0(4) 1.480(2)Ru(1) 5(4) 2.3518(7) S(4) C(8) 1.789(3)5(1) 0(1) 1.476(2) 5(4) C(10) 1.773(3)S(1) C(1) 1.801(3) C(1) C(2) 1.518(5)5(1) C(4) 1.780(3) C(2) C(3) 1.523(4)S(2) 0(2) 1.473(2) C(6) C(7) 1.523(4)S(2) C(3) 1.794(3) C(7) C(8) 1.530(4)270Appendix D^ Cis-RuC12(BMSP)2D-10(d) Bond Angles (0) with Estimated Standard Deviationsatom atom atom angle atom atom atom angleC1(1) Ru(1) C1(2) 86.66(2) Ru(1) S(2) C(5) 112.3(1)C1(1) Ru(1) 5(1) 178.25(2) 0(2) 5(2) C(3) 105.5(1)C1(1) Ru(1) S(2) 83.42(2) 0(2) S(2) C(5) 106.7(1)C1(1) Ru(1) S(3) 92.48(2) C(3) S(2) C(5) 98.9(2)C1(1) Ru(1) 5(4) 91.92(2) Ru(1) 5(3) 0(3) 113.91(8)C1(2) Ru(1) 5(1) 91.85(2) Ru(1) S(3) C(6) 115.80(9)C1(2) Ru(1) S(2) 91.92(2) Ru(1) S(3) C(9) 113.6(1)C1(2) Ru(1) 5(3) 178.42(2) 0(3) S(3) C(6) 105.5(1)C1(2) Ru(1) S(4) 84.36(2) 0(3) 5(3) C(9) 106.8(1)S(1) Ru(1) 5(2) 97.55(2) C(6) S(3) C(9) 99.9(1)5(1) Ru(1) 5(3) 89.04(2) Ru(1) 5(4) 0(4) 116.51(9)5(1) Ru(1) 5(4) 87.02(2) Ru(1) 5(4) C(8) 115.09(9)S(2) Ru(1) 5(3) 86.66(2) Ru(1) 5(4) C(10) 111.2(1)5(2) Ru(1) 5(4) 174.21(2) 0(4) S(4) C(8) 104.9(1)5(3) Ru(1) 5(4) 97.00(2) 0(4) S(4) C(10) 107.1(1)Ru(1) S(1) 0(1) 115.05(9) C(8) 5(4) C(10) 100.6(1)Ru(1) S(1) C(1) 115.3(1) S(1) C(1) C(2) 114.8(2)Ru(1) 5(1) C(4) 113.3(1) C(1) C(2) C(3) 113.1(3)0(1) S(1) C(1) 105.9(1) 5(2) C(3) C(2) 114.4(2)0(1) 5(1) C(4) 106.4(1) 5(3) C(6) C(7) 115.0(2)C(1) S(1) C(4) 99.3(1) C(6) C(7) C(8) 113.4(2)Ru(1) S(2) 0(2) 116.07(8) S(4) C(8) C(7) 115.6(2)Ru(1) S(2) C(3) 115.5(1)271"""•%-:?0`Appendix D^ RuC12(BMSP)2D-10(e) A stereoview of the Unit Cell of cis-RuCl2(BMSP)2D-10(f) An ORTEP Diagram for cis-RuCl2(BMSP)2, Showing 50% ProbabilityThermal Ellipsoids272Appendix E: Unresolved ReactionsE-1 IntroductionAppendix E describes the reactions that were carried out during this thesis work,but which remain unresolved. Nitroimidazole complexes of NM) were synthesized butcould not be purified. The reaction of cis-RuC12(DMS0)4 with 2-amino-5-nitrothiazole(ANT) resulted in the isolation of a Ru/DMSO/ANT complex which, again, could notbe separated from the starting materials. The reaction of cis-RuC12(1'MS0)4 with a 5-nitroimidazole, SR 2508 (see Section 1.9.2 and Figure 1.2, p.15), and the details of theRu-TMSO-SR 2508 complex isolated are discussed. The reaction of BMSB (1,4-bis(methylsulfinyl)butane) and BESB (1,4-bis(ethylsulfinyl)butane) with the "ruthenium-blue" solutions (Section 2.4.1, p.45) resulted in complexes that could not becharacterized. Nitroimidazole complexes of the Ru-chelating sulfoxide complexes(discussed in Chapter 4) were synthesized but could not be purified.E-2 Reactions of IrC13 with NitroimidazolesAttempts were made to synthesize nitroimidazole complexes of Ir(III) fromIrC13.3H20 and 4-nitroimidazole, N-methyl-4-nitroimidazole, SR 2508 and ANT but,in all cases, mixtures were obtained which could not be separated into pure components.Two typical reactions are described below.(a) IrC13.3H20 (0.22 g, 0.48 mmol) was added to a solution of 4-nitroimidazole(0.16, 1.4 mmol) in Et0H or Me0H (10 mL) and the resulting suspension refluxedovernight in air. The IrC13.3H20 dissolved slowly, and the resulting solution turned273brown. A small amount of precipitate (grey-brown) formed overnight and was collectedin air. The volume of the reaction solution was reduced by half and ether (25 mL)added slowly. More precipitate came out of solution and was collected in air and driedin vacuo at 70°C.Typically, the precipitates were sparingly soluble in Me0H and Et0H andinsoluble in most common organic solvents and H20. The melting points of theprecipitates were generally greater than 300°C and no decomposition was observed.Two components, one of which was free nitroimidazole, were detected using thin layerchromatography (Si-gel, Et0H). The two fractions could not be separated using columnchromatography. The IR spectrum of the precipitate was essentially identical to that ofthe free ligand. The only peaks detected in mass spectroscopy (El or FAB) were thosedue to the free ligand and, in the case of FAB, those due to the matrix.(b) A mixture of IrC13.3H20 (0.35 g, 0.70 mmol) and ANT (0.29 g, 1.1 mmol)was added to Me0H (15 mL) and the resulting suspension refluxed for 6 h. Thereactants dissolved and the solution became a dark red colour. The reaction mixture wasthen filtered in air and the volume reduced (5 mL) by vacuum; diethyl ether (40 mL)was then added and a red solid precipitated from the solution. The precipitate wascollected in air and dried in vacuo at 70°C. The red solid consists of three components(shown using thin layer chromatography: Florisil; 20% H20; 55% Et0H; 25%CH2C12). Column chromatography was used in an attempt to separate the threefractions but only the first fraction (which consisted of free ANT) could be isolatedpure. The remaining two fractions contained substantial amounts of ANT.274E-3 The Reaction of cis-RuC12(DMS0)4 with 2-amino-5-nitrothiazo1e (ANT)A solution of cis-RuC12(DMS0)4 (0.24g, 0.5 mmol) and ANT (0.29 g, 2 mmol)in Me0H (20 mL) was refluxed for 4 h; the solution became a deep red and was filteredin air. The volume of the reaction solution was reduced (10 mL) and a red complexprecipitated upon the addition of diethyl ether (30 mL). The red precipitate is solublein most organic solvents but contains substantial amounts of free ligand. This mixturecould not be purified by recrystallization (Me0H/diethyl ether; acetone/ diethyl ether;CH2C12/ diethyl ether), sublimation (130°C, vacuum) or column chromatography(Florisil, Me0H/CH2C12 1:9).E-4 The Reaction of cis-RuC12(TMS0)4 with SR 2508The complex RuC12(TMS0)2(SR 2508) was reportedly synthesized from thereaction of cis-RuC12(TMS0)4 and SR 2508 [50]. Subsequent attempts to synthesizemore of the SR 2508 complex, however, indicated that there were some inconsistencies(see below) in the original report [50]. The reaction details were worked out during thispresent thesis work in conjunction with Dr. J. Jaswal and are described below.A solution of cis-RuC12(TMS0)4 (0.29 g, 0.50 mmol) and SR 2508 (0.14 g,0.70 mmol) in methanol (20 mL) was refluxed in N2 for 12 h. The resulting dark bluereaction solution was then filtered hot and the volume reduced to 8 mL. Diethyl ether(30 mL) was added slowly to the concentrated reaction mixture, and a blue solidprecipitated which was collected and dried in vacuo at 70°C. The precipitate consistedof four components which were separated by column chromatography (Si-Gel,275Me0H/CH2C12, 1:9). The first colourless fraction collected consisted of free SR 2508,the second yellow fraction consisted of cis-RuC12(TMS0)4 and the third blue fractionwas RuC12(TMS0)2(SR 2508).2H20. A fourth purple band was collected but nocomplex was isolated from the solution.E-4(a) Data for RuCl2(TMS0)2(SR 2508).2(H20)Anal. calc. for C15H30C12N408RuS2: C, 28.58; H, 4.76; N, 8.88. Found: C,28.72; H, 4.54; N, 9.11%. Xmaxnm (log e), CHC13: 720 (3.16); 352 (3.65). IR vco:1683, vso: 1115, 1051, 1036, vNo: 1520, 1483 1473 cm-1. 1H NMR (300 MHz,CD30D, -77°C)6 b 8.39, 8.10 ppm (s, 1H each, coordinated SR 2508); 7.54, 7.24ppm (s, 1H each, free SR 2508). In acetone-d6, ambient temperatures; 45 8.48, 8.05ppm (s, 1H each, coordinated SR 2508).The spectral data for the complex isolated in this work indicate that thenitroimidazole dissociates rapidly in Me0H, Et0H and H20 at ambient temperatures,while in acetone, CHC13 and CH2C12, the complex remains intact. A previous accountof this reaction [50] indicated that a Ru-TMSO-SR2508 complex was isolated purewithout any chromatographic steps and that the complex remains intact in aqueoussolution; in light of the data obtained for the present complex, however, it is likely thatthe reported complex [50] is actually a mixture of starting material and the product.6 The only peaks reported in the 1 H NMR spectrum are those due to the aromaticprotons of the nitroimidazole.276E-5 The Reactions of BMSB and BESB with the "Ruthenium-Blue" SolutionsThe two title sulfoxides (RS(0)(CH2)4S(0)R, BMSB, R = Me; BESB, R = Et)were refluxed with the "ruthenium-blue" solutions (Section 2.4.1, p.45). In both cases,yellow precipitates were obtained which were insoluble in most common solvents; nospectral data could be obtained and the elemental analysis for C and H were variablefrom reaction to reaction. Both samples were submitted for analysis by massspectroscopy (El and FAB); no peaks were detected using El while the only peaksobserved in FAB were those due to the matrix. The precipitates are thought to bemixtures which could not be purified.E-6 The Reaction of 4-Nitroimidazole with the Ru Complexes of ChelatingSulfoxidesMethanolic solutions of the complexes trans-RuC12(BMSE)2, cis-RuC12(BESE)2,trans-RuC12(BPSE)2, and cis-RuC12(BMSP)2 (see Section 4.3, p.152) were refluxedwith 4-nitroimidazole in attempts to synthesize Ru-chelating sulfoxide-nitroimidazolecomplexes. A typical reaction is outlined below.RuC12(BMSP)2 (0.068g, 0.134 mmol) was dissolved by refluxing in Me0H/H20(15:1) under N2; 4-nitroimidazole (0.031 g, 0.27 mmol), previously dissolved in Me0H(5 mL), was added and the reaction mixture refluxed for a further 6 h. The solutionturned dark red and small amounts of a red complex precipitated. The reaction solutionwas filtered and the solvent removed by vacuum; the remaining red solid was thenreprecipitated from Me0H/diethyl ether (5:30 mL), collected under N2 and dried in277vacuo at 70°C.The red precipitates were found to be mixtures consisting of the starting materialand a Ru-sulfoxide-nitroimidazole complex. The only peaks detected in the 1H NMRspectrum (300 MHz, CD2C12) were those due to the aromatic protons in free 4-nitroimidazole. The only peaks found in mass spectroscopy (El and FAB) correspondedto that of the free 4-nitroimidazole and those due to the matrix (in FAB). Attempts topurify the red precipitate using column chromatography (Si-gel, Florisil, alumina;CH2C12/Me0H/acetone), sublimations and recrystallizations (CH2C12/ether,CH2C12/acetone, Me0H/ether, H20/Me0H) were unsuccessful.278


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