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Phosphine complexes of zirconium, hafnium and the lanthanoid metals Haddad, Timothy Samir 1990

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PHOSPHINE C O M P L E X E S O F ZIRCONIUM, H A F N I U M A N D T H E LANTHANOID METALS By T I M O T H Y SAMIR H A D D A D B. Sc., The University of Regina, 1984 M. Sc., The University of British Columbia, 1987 A THESIS SUBMITTED IN PARTIAL F U L F I L L M E N T O F T H E REQUIREMENTS FOR T H E D E G R E E OF D O C T O R OF PHILOSOPHY in T H E F A C U L T Y OF G R A D U A T E STUDIES Department of Chemistry  We accept this thesis as conforming to the required standard  T H E UNIVERSITY OF BRITISH C O L U M B I A D E C E M B E R 1990 © Timothy Samir Haddad  In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department  or  by  his or  her  representatives.  It  is  understood that  copying or  publication of this thesis for financial gain shall not be allowed without my written permission.  Department of  CLMem  The University of British Columbia Vancouver, Canada Date  DE-6 (2/88)  Dec  £Q  l^lO  ii  ABSTRACT  The synthesis of a variety of new lanthanoid phosphine complexes has been achieved by complexing either one or two amido-diphosphine ligands to yttrium, lutetium or lanthanum. At room temperature, the seven-coordinate bis(amidodiphosphine) complexes, MCl[N(SiMe2CH2PR2)2l2- are fluxional and display NMR spectra indicative of complexes where the phosphorus donors are rapidly exchanging, probably via a dissociation-reassociation pathway.  It is possible to generate  thermally unstable hydrocarbyl complexes of the type, M(R)[N(SiMe2CH2PMe2)2]2» which undergo a clean first order elimination of R-H to generate cyclometallated i  1  complexes of the type, M[N(SiMe CHPMe2)(SiMe CH PMe2)][N(SiMe CH PMe ) ]; 2  2  2  2  2  2  2  the yttrium derivative was crystallographically characterized. These thermally robust compounds will undergo a-bond metathesis with H2 and D2 at high temperature, but appear to be too sterically congested to react with larger molecules. The synthesis of a series of mono(amido-diphosphine) lanthanoid complexes, M C l 2 [ N ( S i M e 2 C H 2 P R 2 ) 2 ] . (R = Me, Ph, Pr', Bu ) has also been achieved. l  Complexes of the type, MCl2[N(SiMe2CH2PMe2)2L are insoluble in hydrocarbon solvents, presumably because they are oligomeric in nature. They will however, dissolve in THF probably forming seven-coordinate bis(THF) monomers. Attempts to alkylate these compounds generally led to decomposition; the cyclometallated 1  1  bis(ligand) complex, M[N(SiMe CHPMe )(SiMe CH PMe )] [N(SiMe CH PMe ) ], 2  2  2  2  2  2  2  2  2  was identified as the major product. A route to a dimeric mono(amido-diphosphine) allyl complex, {YCl(allyl)[N(SiMe2CH2PMe2)2]}2 (characterized by crystallography) was found via the reaction of allyl-MgCl or Mg(allyl)2(dioxane) with YCl[N(SiMe2CH2PMe2)2l2-  The mono(ligand) complexes containing bulky  iii phosphine donors (R  = P h , B u , Pr-) are soluble i n h y d r o c a r b o n l  solvents;  YCl2[N(SiMe2CH.2PPr-2)2] can be isolated as either a T H F adduct or as the basefree dimer.  A new reaction, mediated by a zirconium or hafnium amido-diphosphine complex, where a l l y l and butadiene moieties are coupled together to generate a coordinated [ r | : r i - - C H 2 = C H C H = C H C H 2 C H 2 C H 2 ] - fragment has been investigated.  The  process is very sensitive to the nature o f the ancillary ligands at the metal.  For  4  1  MCl(ri -C4H )[N(SiMe2CH2PR2)2] 4  6  complexes, after the addition o f a l l y l M g C l , the  transformation takes about one hour when M = H f & R = Pr-, two hours when M = Z r & R = Pr-, a week when M = H f & R = M e , and results only i n decomposition when M = Z r & R = M e . Similarly, for the zirconium mediated coupling of 1-methylallyl with butadiene, when R = M e , decomposition occurs and when R = Pr-, after two hours the coupling is complete. T w o of the four possible coupled products are formed in unequal amounts, and the coupling occurs exclusively at the substituted end o f the 1m e t h y l a l l y l unit as determined by X-ray crystallography.  W h i c h diastereomer is  formed i n excess was not determined.  The reduction o f ZrCl3[N(SiMe2CH2PR2)2] (R = P r or Bu-) with Na/Hg 1  amalgam under nitrogen results i n the formation of a binuclear zirconium dinitrogen complex, {ZrCl[N(SiMe2CH2PR2)2]}2(M--'n :'n -N2). 2  2  X-ray crystallography (for R =  Pr-) reveals that the N2 ligand is symmetrically bound in a side-on fashion to both metals.  In addition, the N — N bond length o f 1.548 (7) A, the longest bond length  ever reported for a dinitrogen complex, indicates that the dinitrogen has been reduced to a N 2 ' hydrazido ligand. 4  Protonation o f the complex with H C l results in a  quantitative formation of hydrazine.  iv  TABLE OF CONTENTS  ABSTRACT  ii  TABLE OF CONTENTS  iv  LIST OF TABLES  vii  LIST OF FIGURES  viii  LIST OF ABBREVIATIONS  xiii  ACKNOWLEDGEMENTS  CHAPTER 1  xvii  GENERAL  INTRODUCTION  1.1  Transition Metal Phosphine Complexes  1  1.2  Phosphine Complexes of the Lanthanid.es and Group 3 Metals  2  1.3  Phosphine Complexes of Hafnium and Zirconium  7  1.4  Summary of Previous Work from Our Laboratory  10  1.5  The Scope of this Thesis  16  1.6  References  18  CHAPTER 2  BIS(AMIDO-DIPHOSPHINE) COMPLEXES OF LANTHANUM, YTTRIUM AND LUTETIUM  2.1  Introduction  23  2.2  Synthesis of Bis(amido-diphosphine) Complexes  24  2.3  NMR Characterization and Fluxional Behaviour  26  2.4  X-ray Crystal Structure Determination of Y^N(SiMe CHPMe )(SiMe CH PMe )][N(SiMe CH PMe ) ]44 2  2.5  2  2  2  2  2  2  Kinetics of the Thermolysis of MR[N(SiMe2CH PMe2)2h 2  2  2  48  2.6  Reactivity of M[N(SiMe CHPMe )(SiMe2CH PMe )][N(SiMe CH2PMe ) ]53 2  2  CHAPTER  2  2  2  2  2.7  Summary  55  2.8  Experimental Procedures  55  2.9  References  64  3  MONO(AMIDO-DIPHOSPHINE) YTTRIUM  COMPLEXES  OF  AND LUTETIUM  3.1  Introduction  3.2  Syntheses o f M C l 2 [ N ( S i M e C H P M e ) 2 ]  3.3  Synthesis and Structure o f  68 2  2  69  2  { Y ( a l l y l ) [ N ( S i M e C H P M e 2 ) 2 ] }2(M^-C1)2  74  3.4  Syntheses of Y C l 2 [ N ( S i M e C H P R 2 ) 2 ] R = P h , Bu-, Pr-  82  3.5  Synthesis and Thermolysis of YCl(Ph)[N(SiMe CH2PPr- )2]  88  3.6  Summary  91  3.7  Experimental Procedures  92  3.8  References  2  CHAPTER  2  4  2  2  2  2  101  ALLYL-DIENE AND  2  COUPLING  AT  HAFNIUM  ZIRCONIUM  4.1  Introduction  102  4.2  Synthesis o f Allyl-Diene Coupled Complexes  103  4.3  Molecular Structures o f HfCn :T| --C7H11 ) [ N ( S i M e C H P P r - ) ] , 4  2  16c, and Zr(Ti :r|--C8Hi3)[N(SiMe CH2PPr-2)2], 4  2  18c  2  2  2  105  4.4  N M R Spectroscopic Characterization  110  4.5  Summary  117  4.6  Experimental Procedures  118  vi  4.7  CHAPTER 5  References  122  SYNTHESIS AND C H A R A C T E R I Z A T I O N O F A SIDE-ON DINITROGEN C O M P L E X  5.1  Introduction  123  5.2  Synthesis of {ZrCl[N(SiMe2CH PPr- )2]}2(N2)  5.3  Molecular Structure of  127  2  2  {ZrCl[N(SiMe CH PPr- )2]} 2(li-Tl :ri -N2)  128  5.4  N M R Spectra of {ZrCl[N(SiMe CH PR2)2]}2(N2)  133  5.5  Reactivity of {ZrCl[N(SiMe CH PPr 2)2])2(N2)  136  5.6  Experimental Procedures  139  5.7  References  141  2  2  THESIS  OF ZIRCONIUM  2  2  2  2  2  2  i  2  S U M M A R Y AND F U T U R E PROSPECTS  144  APPENDIX  148  A - l X-ray Crystallographic Analysis of Y[N(SiMe2CHPMe )(SiMe CH PMe )][N(SiMe CH2PMe ) ]148 2  2  2  2  2  2  2  A - 2 X-ray Crystallographic Analysis of {Y(Ti3-allyl)[N(SiMe CH2PMe2)2]}2(li-Cl)2 2  155  A - 3 X-ray Crystallographic Analysis of Hf(ri :ri 4  i)[N(SiMe CH PPr-2) ]  --C7H1  2  2  2  160  A - 4 X-ray Crystallographic Analysis of Zr(n.4 r| l - C H i ) [ N ( S i M e C H P P r - ) ] :  8  3  2  2  2  2  165  A - 5 X-ray Crystallographic Analysis of {ZrCl[N(SiMe CH PPri )2] }2(M--'n :Tl -N2) 2  2  2  2  2  173  vii  LIST OF TABLES Table 1.1  Phosphine Complexes of the Group 3 Metals.  3  Table 1.2  Phosphine Complexes of the Lanthanides.  4  Table 1.3  Group 3 and Lanthanide Metal Phosphorus Bond Lengths.  6  Table 1.4  Phosphine Complexes of Hafnium and Zirconium Prior to 1980.  8  Table 2.1 T a b l e 2.2  1  Jp.y and Jp.p Coupling Constants for MR[N(SiMe2CH2PMe2)2l2- 33 2  -Jp.Y and Jp.p Coupling Constants for 2  M[N(SiMe CHPMe )(SiMe CH PMe )][N(SiMe CH PMe )2]. 2  Table 2.3  2  2  2  2  2  2  2  41  Selected Bond Lengths for Y[N(SiMe CHPMe )(SiMe CH PMe )][N(SiMe CH PMe ) ].  44  Selected B o n d Angles for I 1 Y[N(SiMe CHPMe )(SiMe CH PMe )][N(SiMe CH PMe ) ].  46  Table 2.5  Rate Data for the Thermolysis of YR[N(SiMe2CH2PMe2)2]2-  50  Table 2.6  Eyring Data for the Thermolysis of YR[N(SiMe2CH2PMe2)2h-  50  Table 3.1  Selected Bond Lengths for  2  Table 2.4  2  2  2  2  2  2  2  2  2  2  2  2  2  2  2  2  2  {Y(allyl)[N(SiMe2CH PMe )2]}2(u.-Cl)2. 2  Table 3.2  74  2  Selected Bond Angles for {Y(allyl)[N(SiMe2CH PMe2)2]}2(li-Cl) . 2  76  2  Table 4.1  Selected Bond Angles for Zr(ri4 jl-C8Hi3)[N(SiMe2CH PPr 2)2]- 105  Table 4.2  Selected Bond Lengths for Zr(r|4:n--C8Hi )[N(SiMe2CH2PPr-2)2] 106  Table 4.3  Selected Bond Lengths for Hf(r| :ri--C7Hii)[N(SiMe2CH2PPr-2)2]  Table 4.4  Selected Bond Angles for Hf(rj4: l-C7Hi )[N(SiMe2CH2PPr- )2]. 105  Table 5.1  Selected Bond Angles for  :r  2  3  4  T1  1  {ZrCl [N(SiMe CH PPr-2)2]} 2(H-il :ri -N2) • 2  2  Table 5.2  2  2  106  2  131  Selected Bond Lengths for {ZrCl[N(SiMe2CH2PPri2)2]}2(lA-Tl :ri -N2).  131  Theoretical and Calculated Hydrazine Concentrations.  138  2  Table 5.3  i  2  viii  LIST OF FIGURES  Figure 1 . 1 A  representation  of Y b [ N ( S i M e 3 ) ' 2 ] ( d m p e ) , 2  t  n  e  f-  rst  crystallographically characterized lanthanide phosphine complex.  5  Figure 1 . 2 Some recently characterized group 4 phosphine complexes (left to right references 44, 45 and 46).  9  Figure 1 . 3 Two target lanthanoid phosphine complexes.  Figure  2.1  17  300 M H z -H N M R spectrum (top, in C 6 D ) and 75.4 M H z 6  1 3  C{ U) l  N M R spectrum  (bottom,  in C 6 D 5 C D 3 ) of  Y ( P h ) [ N ( S i M e C H P M e 2 ) 2 l 2 recorded at room temperature. 2  2  Solvent peaks are marked with an asterisk.  27  Figure 2.2 Figure 2.2: 300 M H z -H N M R spectrum (top) and 75.4 M H z 1  3  C  { -H)  NMR  spectrum  Y(Ph)[N(SiMe CH PMe )2]2in C D C D 2  2  2  6  5  (bottom)  of  recorded at -59 ° C .  3  Solvent peaks are marked with an asterisk. Figure 2.3  121  MHz  3  -P{-H}  Y(Ph)[N(SiMe CH PMe )2]2in 2  2  2  28  NMR C D CD 6  5  spectrum  of  recorded at -49 ° C  3  (top) and a simulation (bottom) using Bruker PANIC software. See Figure 2.5 and Table 2.1 for details.30 Figure  2.4  121  MHz  3  1  P {  1  H}  NMR  spectrum  of  L u ( P h ) [ N ( S i M e C H P M e 2 ) 2 ] 2 in C D C D recorded at -59 °C 2  2  6  5  3  (top) and a simulation (bottom) using Bruker PANIC software. See Figure 2.5 and Table 2.1 for details. Figure 2.5  31  Three possible structures based on a pentagonal bipyramidal geometry for M R [ N ( S i M e 2 C H 2 P M e 2 ) 2 ] 2 complexes in the low temperature limit.  The P { - H } N M R spin system in the 3 1  pentagonal plane is also shown.  32  ix  Figure  2.6  121 M H z -P{-H} N M R spectrum of YCl[N(SiMe CH PPh2)2]2 3  2  2  in C6D5CD3 recorded at -59 C (top) and a spectral simulation e  using Bruker PANIC software (below). Figure  2.7  35  121 M H z P{ lH} NMR spectra of LaCl[N(SiMe CH PPh2)2]2 in 31  2  2  CD3C6D5 as a function of temperature. The actual concentration is unknown. An impurity, HN(SiMe2CH2PPh ) , is indicated with 2  2  an asterisk. Figure  2.8  37  121 M H z P{ H} N M R spectrum (top) and simulation (bottom) of 31  1  Y^N(SiMe CHPMe )(SiMe CH PMe )][N(SiMe CH PMe ) ],7a, 2  2  2  2  2  2  2  2  2  in CD3C6D5 recorded at -29 °C. See Table 2.2 for details. Figure  2.9  39  121 M H z P { H ) NMR spectrum (top) and simulation (bottom) of 31  1  Lu[N(SiMe CHPMe )(SiMe CH PMe )][N(SiMe CH PMe ) ],8a, 2  in C D C 6 D 3  Figure  2.10  8 9  5  2  2  2  2  2  2  2  2  recorded at -29 °C. See Table 2.2 for details.  40  Y N M R spectra of l a (top, 19.6 MHz) in CD3C6D5/THF and 7a  (middle, 24.6 MHz) in CD3C6D5. The theoretical spectrum of 7a, based on the couplings constants in Table 2.2, is also shown (bottom). Figure  43  2.11 Chem 3 D ® core view (top) and ORTEP stereoview (bottom) of Y[N(SiMe CHPMe )(SiMe CH PMe )] [N(SiMe CH PMe ) ]. 2  2  2  2  2  2  Figure  2.12 A possible transition state for the elimination of R—H.  Figure  2.13 The first-order  rate  plots  for the  Y(CH C6H )[N(SiMe CH PMe ) ] , 2  5  2  2  2  2  2  2  2  2  45 48  thermolysis  of  5a, and the Eyring plots for  the thermolysis of Y ( R ) [ N ( S i M e C H P M e ) ] , R = C H C H , 2  CD C D , C H . 2  6  5  6  5  2  2  2  2  2  6  5  49  Figure  3.1  N M R spectra of LuCl2[N(SiMe CH PMe2)2]- H a : 300 M H z -H 2  2  spectrum (top) and 75.4 M H z C{-H} spectrum (bottom), both in 13  C6D5CD3/THF. The C 6 D 5 C D 3 peak is marked with an asterisk. Figure  3.2  Three views of  73  {Y(allyl)[N(SiMe CH PMe2)2]}2(H-C1) ,12a. 2  2  2  At the top are two Chem 3 D ® views; the figure at the top right shows the approximate pentagonal bipyramidal geometry at yttrium (based on the assignment of two coordination sites for the allyl moiety): the N and CI' atoms are axial while PI, P2, CI and the allyl are equatorial.  The bottom view is the O R T E P  stereoview showing the complete atom labelling scheme. Figure  3.3  300 M H z * H  NMR  spectra  of  75  {Y(allyl)[N(SiMe 2  C H P M e ) 2 ] } 2 ( u - C l ) 2 , 12a, at + 80 ° C (top) and at -50 ° C 2  2  (bottom) in C 6 D 5 C D 3 (marked with asterisks). Figure  3.4  Temperature  invariant  NMR  spectra  {YCl2[N(SiMe2CH2PPr- )2]}2- 10c in C D : 6  2  78 of  121 M H z -P{lH} 3  6  NMR spectrum (top) and 300 M H z -H N M R spectrum (bottom). Figure  3.5  121 M H z  31  P{-H}  variable  temperature  85  N M R spectra of  YCl2[N(SiMe2CH PPr-2)2](THF) in C D C D . 2  Figure  3.6  Temperature  3  invariant  NMR  6  spectra  [ N ( S i M e 2 C H P P r - ) 2 ] , 14c, in C D C D . 2  2  3  87  5  6  5  of  YCl(Ph)-  121 M H z P{-H} 31  N M R spectrum (top) and 300 M H z -H N M R spectrum (bottom). The C D 3 C 6 D 5 resonances are marked with an asterisk. Figure  3.7  89  121 M H z -P{-H} N M R spectra (in C D C D ) of 15c and a 3  3  6  5  possible structure for this complex. Figure  4.1  90  Four possible isomers for the coupling of 1-methylallyl with butadiene.  104  xi Figure  4.2  Molecular structure of 18c.  Zr(rj :Ti--CgHi3)[N(SiMe2CH2PPr-2)2]4  Two Chem 3D®  views showing the two  different  diastereomers and an O R T E P stereoview showing the complete atom numbering scheme. Figure  4.3  108  Molecular structure of H f ( r | : r i . l - C 7 H i i ) [ N ( S i M e 2 C H P P r - ) 2 ] 4  2  2  16c. A Chem 3D® view for comparison with 16c and an O R T E P stereoview showing the complete atom numbering scheme. Figure  4.4  121 M H z 31p{lH} N M R spectra in C 6 D  of Zr(Tl :Tl -C8Hi3)4  6  109  1  [N(SiMe2CH2PPr-2)2]» 18c. The upper spectrum is of the crude reaction mixture and shows the different proportions of the two diastereomers, the lower spectrum is of a 1:1 crystallized products.  mixture of  Z r C l ( T | - C 4 H ) [ N ( S i M e 2 C H 2 P P r - 2 ) 2 ] is 4  6  marked with an asterisk. Figure  4.5  MHz  300  l  H  Ill  NMR  spectra  of  Zr(ri :n. 1 - C H i ) 4  8  3  [N(SiMe CH PPr-2)2], 18c, in QDe. 2  Figure  4.6  112  2  A portion of the 75.4  M H z ^ C f - H } N M R spectra in C 6 D  6  of  Zr(rt :Tii-C8Hi3)[N(SiMe CH2PPri2)2]. 18c.  113  4  2  Figure  4.7  121.4 M H z 3-P{ -H} NMR spectra in T H F / C D of C H M g C l and 6  6  3  5  Z r C l ( r i - C 4 H 6 ) [ N ( S i M e 2 C H 2 P P r 2 ) 2 ] after 50 mins (upper) and 4  i  i  120 mins (lower). Note that the two scales are not identical. Figure  4.8  The numbering scheme used for the N M R  spectroscopic  assignments. Figure  5.1  5.2  118  Representations of the first crystallographically characterized end-on mononuclear and bridging dinuclear N2 complexes.  Figure  116  Three views of the molecular structure of 19c. At the top are two Chem 3D® views showing the symmetric environment about the zirconium centres. The top left view is looking down the Zr—Zr  123  xii  axis, while at the top right is a view showing the close contact of the isopropyl groups across the N bridge. At the bottom is a 2  stereoview of this complex showing the disorder in the ligand backbone. Figure  5.3  130  300 M H z -H N M R spectra of {ZrCl[N(SiMe CH2PBu-2)2]}2(N2) 2  in C 6 D 5 C D 3 . The upper trace at + 60 ° C and the lower spectrum was recorded at 20 ° C . Figure  5.4  121 M H z P { - H } 31  134 N M R spectra  of  {ZrCl[N(SiMe 2  CH2PBu-2)2]}2(N2) in C6D5CD3. The upper trace at + 25 ° C and the lower spectrum was recorded at 0 ° C . Figure  5.5  135  121 M H z P{-H} (upper trace) and 300 M H z -H N M R (lower 31  trace)  spectra  of  the crude  reaction  {ZrCl[N(SiMe CH PPr-2)2] }2(N2) + CDCI3. 2  2  mixture  from 137  xiii  LIST  OF  ABBREVIATIONS  The following list of abbreviations, most of which are commonly used in the chemical literature, will be employed in this thesis:  A  angstrom  Anal.  analysis  Ax  axial  br  broad  Bz  benzyl  Bu  butyl  Bu-  tertiary butyl  °C  degree centigrade  Calcd.  calculated  Ci  ipso-carbon  cf.  compare  Chem 3D®  molecular modelling program for the Macintosch  !3C{-H}  observe carbon while decoupling proton  cm  centimetre  Cm  mera-carbon  CN  coordination number  Co  ortho-caibon  c  para-carbon  p  Cp  cyclopentadienyl anion, C5H5-  Cp*  per(methyl)cyclopentadienyl anion, C s M e s  Cp'  mono(methyl)cyclopentadienyl anion, MeCshLf  A  heat  -  xiv AG*  free energy of activation  AH*  enthalpy of activation  AS*  entropy of activation •  Au  peak separation at coalescence  c  8  chemical shift  d  doublet  d  n atoms of deuterium per molecule  n  deg  degree  dmpe  l,2-bis(dimethylphosphino)ethane  dmpm  l,l-bis(dimethylphosphino)methane  dppe  l,2-bis(diphenylphosphino)ethane  e  molar extinction coefficient  e.g.  for example  Eq  equatorial  eu  entropy units  fac  facial  E  gram  h  Planck's constant  H  a  anri-hydrogen  m  meso-hydrogen  H  Hm  mera-hydrogen  H  orr/w-hydrogen  H H  0  p  s  para-hydrogen syn-hydrogen  Hz  Hertz  i.e.  that is  IR  infrared  XV  nT  A-B  n-bond coupling constant between A and B atoms  K  degree Kelvin  k  rate constant  k  B  Boltzmann constant  kc  rate constant at the temperature of coalescence  Kcal  kilocalorie  Kgq  equilibrium constant  k  H  observed rate constant for a protio-isomer  k  D  observed rate constant for a deuterio-isomer  kobs  observed rate constant  ^•max  wavelength of maximum absorbance  L  litre  M  molarity  Me  methyl  mer  meridional  mg  milligram  MHz  megaHertz  mL  millilitre  mmol  rnillimole  mol  mole  M.Sc.  master of science  NMR  nuclear magnetic resonance  nm  nanometre  Np  neopentyl  ORTEP  Oak Ridge Thermal Ellipsoid Plotting Program  P  pentet  xvi PANIC  Parameter Adjustment in N M R by Iteration Calculations  Ph  phenyl  %  percent  %T  percent transmittance  31  P{!H}  observe phosphorus while decoupling proton  Pr-  isopropyl  q  quartet  s  singlet  sec  second  sept  septet  t  triplet  t-butyl  tertiary butyl  T  temperature of coalescence  c  THF  terahydrofuran  trmpe  MeC(CH2PMe2>3  TMEDA  tetramethylethylenediamine  UV-VIS  ultraviolet-visible  xvii  ACKNOWLEDGEMENTS  First and foremost, I would like to thank my supervisor Mike Fryzuk for all his support throughout my time here at UBC. Being a part of his ever-changing group has given me the opportunity to meet every kind of post-doc and grad-student imaginable. Thank-you, Pat, Myl, Guy, Cam, Neil, Lisa, Dave, Dave, Chas, Alan, Randy, Kiran, Jesse, Craig, Cindy, Brian, Bobbi, Warren, Graham, Pauline and Patrick for your own individual outlook on it all.  I would also like to acknowledge the help I had from all the support staff here at U B C :  the guys in the electrical, mechanical and glass-blowing shops, the N M R  staff, P. Borda the elemental analysis expert, and Steve Rettig, the crystallographer who solved all the crystal structures in this thesis.  Many thanks to all the grad-students whose interests (apart from chemistry) such as soccer, football, pub-crawls, skiing, hiking and auto-repair have allowed me a great deal of variation in my leisure time.  And thank-you Michele for making these last two years so much better than the first four that I spent here in Vancouver.  1  C H A P T E R 1:  1.1  G E N E R A L INTRODUCTION  Transition Metal Phosphine Complexest  The phosphine ligand has played a pivotal role in the development of transition metal coordination and organometallic chemistry. 1  2  The synthetic flexibility and  versatility of this ligand type have permitted the isolation of numerous unique and interesting complexes. The phosphorus donor has many beneficial features which can be used to design ligands to impart a desired stereo-electronic environment.  It is  possible to use a phosphine ligand which is a strong a-donor and either of small steric bulk (e.g., PMe3) or one which is enormous in relative size (e.g., PBu 3). In addition, l  phosphorus donors capable of 7C-backbonding with the metal can be utilized and these are also available in a variety of sizes (e.g., the small PF3 or the much larger P(OBu )3 ligand). l  Phosphine donors have also been combined into chelate-type  ligands to increase the stability of the ligand-metal interaction , and this has aided the 3  isolation and study of coordinatively unsaturated complexes.  This donor type has  been used in the synthesis of chiral ligands; complexes containing such ligands are used to bring about enantioselective processes in both the drug industry and the 4  synthesis of natural products. In addition to this synthetic flexibility, this donor type 5  allows an excellent insight into reactivity as phosphorus-31 is a spin 1/2 100% natural abundance nucleus.  It is easily observable by NMR spectroscopy and both the  chemical shift and the observed coupling constants yield valuable stereochemical and electronic information.  6  t Throughout this thesis, the term "phosphine donor" is used to refer to a phosphorus-based ligand which forms a a-bond to a metal via donation of its lone pair of electrons. Included in this definition are phosphites, P(OR)3, while phosphides, PR2", are excluded.  2 While there are countless phosphine complexes of the transition metals, there are still areas of the periodic table for which such complexes are rare or even unknown.  7  In particular, phosphine complexes of the early transition elements and  lanthanides, where the metal is usually in a high oxidation state, are rare and these 8  compounds are often unstable with respect to phosphine dissociation. One reason advanced for this instability is that these metals are hard acids while the phosphine 9  ligand is considered to be a soft base.  10  Therefore, such a mismatch in donor and  acceptor should result in only weakly bonded phosphines. However, if the metal is exposed to no other ligand, such phosphine complexes should be isolable. It is with these early metal phosphine complexes (and the lack thereof) that this thesis is concerned. In particular, phosphine donor-containing complexes of the group 3 and 4 metals and the lanthanides will be discussed.  1.2 Phosphine Complexes of the Lanthanides and Group 3 Metals  Table 1.1, listing the syntheses of all the known group 3 phosphine complexes, shows how rare are these species (new complexes synthesized for this thesis have been omitted from Tables 1.1-1.4). recently been reported.  In fact, genuine phosphine complexes have only  There is some doubt about the authenticity of the dppe  adducts of SCX3 as the reported elemental analyses are very p o o r , but the other 11  three scandium phosphine complexes have been crystallographically characterized. These derivatives show how the small, basic PMe3 ligand can be used to stabilize and prevent oligomerization or decomposition of the the highly reactive scandium-hydride and -alkyl units. The chemistry associated with these PMe3 stabilized compounds has been reported  12  to involve phosphine dissociation to yield a coordinatively  unsaturated complex which then undergoes a variety of interesting organometallic reactions. The yttrium complex, Y(OCBu-2CH2PMe2)3, illustrates the use of hybrid  3  chelating ligands to generate phosphine complexes.  13  It is noteworthy that no  phosphine complexes of lanthanum or actinium have been reported.  Table 1.1:  Phosphine Complexes of the Group 3 Metals.  Complex  Synthesis  [ScCl (dppe)] 3  x  5  5  4  2  3  11  ScBr + dppe  1969  11  2  2  Y(OCBu CH PMe ) 2  2  3  4  5  4  2  3  (Cp*NBu-)ScR + PMe + H 3  2  [(Cp*NBut)Sc(u-C H )(PMe )] 2  1969  [Me Si(C Me ) ]ScR + P M e + H  3  [(Cp*NBu-)Sc(n-H)(PMe )]  t  S c C l + dppe 3  x  [Me Si(C Me ) ]ScH(PMe ) 2  Ref  3  [ScBr (dppe)i. ] 3  Year -  3  2  1988 1  2  2  [(Cp*NBu-)Sc(ii-H)(PMe )] + C H 3  2  2  2  1988  15  1988  13  4  Y C 1 + 3/2 [Li(OCBu-2CH PMe )]2 3  4  2  Table 1.2 lists the syntheses of all the known lanthanide phosphine complexes. For only six of the fourteen lanthanide metals have such complexes been isolated. There is no reason to suspect that phosphine complexes of Pr, Pm, Sm, Gd, Tb, Dy, Er or Tm are not isolable. In fact Dr. David J. Berg, a former postdoctoral fellow in our laboratories, synthesized and isolated the first such complexes of Sm and Er, as well as other examples with Ce, Eu and Y b .  1 6  The first evidence for a lanthanide phosphine complex was obtained in 1965 17  and was based on the changes observed in the UV-VIS spectrum of C p Y b upon 3  addition of PPh . This adduct was isolated and characterized by elemental analysis. 3  18  Thirteen years later another report was published, claiming the observation (via UVVIS spectroscopy) of the formation of a variety of phosphine adducts of C p Y b . 3  4 However, only a poor elemental analysis of Cp3Yb(PH2Cy) was reported and the attempted isolation of other adducts led to mixtures contaminated with Yb(III) phosphides.  19  Table 1.2: Phosphine Complexes of the Lanthanides. Year ef.  Synthesis  Complex  Cp Yb(L): L = PPh 3  C p Y b + PPh 3  3  Cp Yb(L): L = PPh , PHPh , PH Ph, 3  R  3  2  2  3  C p Y b + L (in situ) 3  1965  17  1978  19  1982  20  1983  21  PCy , PHCy , PH Cy, PMe Ph 3  2  2  Yb[N(SiMe ) ] L : L 3  2  2  2  2  = 2PBu , dmpe Y b [ N ( S i M e ) ] ( O E t ) + L  2  Eu[N(SiMe ) ] (dmpe)i. 3  2  2  Eu[N(SiMe ) ] (PBu ) 3  2  2  3  Cp Yb(L): L = PEt 3  3  3  5  2  2  2  3  2  3  NaEu[N(SiMe ) ] + 2 PBu 3  3  2  3  Cp* Eu(OEt ) + L  Cp* Yb(L): L = dmpe, dmpm  Cp* Yb(OEt ) + L  Cp* YbCl(dmpm)  Cp* Yb(dmpm) + Y b C l  2  2  3  Yb(BH Me) (dmpe)i. 3  1983  2  2  3  3  H o C l + 3 L i B H M e + dmpe  5  3  3  3  Cp Ce(PMe )  Cp' Ce(THF) + excess P M e  3  3  2  3  2  1985  3  2  2  3  Cp' Ce(THF) + P ( O C H ) C E t  3  Nd(OCBu- CH PMe ) 2  2  3  Cp' Ce[P(OCH ) CEt] 3  23  Y b C l + 3 L i B H M e + dmpe  5  Cp LuCl + L i C H P M e  2  1985  3  Cp Lu(CH PMe ) 2  22  2  2  Ho(BH Me) (dmpe)i. 3  2  3  3  Cp* Eu(L): L = dmpe, dmpm 2  2  2NaEu[N(SiMe ) ] + 3 dmpe  C p Y b + PEt  3  2  3  3  2  3  N d C l + 3/2 [ L i ( O C B u C H P M e ) ] 3  t  2  2  2  2  24  1987  25  1988  26  1988  13  5  It was not until 1982 that the first lanthanide phosphine complex was fully characterized.  20  Dmpe and PBU3 adducts of Yb[N(SiMe )2l2 and Eu[N(SiMe3)2]2 3  were synthesized via displacement of coordinated diethyl ether, and the ytterbium derivative, Yb[N(SiMe3)2]2(dmpe), was characterized by X-ray crystallography. The X-ray structure revealed that this complex contained two unusual agostic silyl methyl groups, making the complex formally six-coordinate (Figure 1.1).  Me Si 3  Figure  1.1:  A  representation  of  SiMe  3  Yb[N(SiMe3)2]2(dmpe),  the  first  crystallographically characterized lanthanide phosphine complex.  Since 1982 a few more phosphine complexes have been reported but such compounds are still rare. Three of these reports are of primary interest because they demonstrate that phosphine complexes of the lanthanides are not necessarily inherently unstable. Equilibrium studies showed a ligand as pyrrolidine and better than THF.  21  that for Cp3Yb(L), PEt3 is as good  The synthesis 25  26  of Cp'3Ce(L) (L =  P M e 3 , P ( O C H 2 ) 3 C E t ) via displacement of T H F by a phosphorus ligand demonstrated that this holds true for Ce(III) as well.  These three examples prove that the  phosphine donor can indeed coordinate strongly to these "hard" metal centres and in some cases will displace T H F from the metal centre.  6  Table 1.3: Group 3 and Lanthanide Metal Phosphorus Bond Lengths.  Complex  Bond Length  CN  Cp' Ce[P(OCH )3CEt]  3.086 (3)  10  1.39  1.70  Cp' Ce(PMe )  3.072 (4)  10  1.39  1.68  Cp*2YbCl(dmpm)  2.941 (3)  8  1.125  1.816  Yb[N(SiMe ) ]2(dmpe)  3.012 (4)  6  1.16  1.85  Nd(OCBu CH PMe )  3.154 (2)  6  1.123  2.031  3.045 (2)  6  1.040  2.005  2.752 (1)  8  1.01  1.74  2.996 (1)  7  0.95  2.05  [ ( C p * N B u t ) S c ( L t - C H ) ( P M e ) ] 2 2.825 (3)  7  0.95  1.88  3  2  3  3  3  t  2  2  2  2  Y(OCBu 2CH PMe ) t  2  2  3  3  Me Si(C Me )2ScH(PMe ) 2  5  4  3  [(Cp*NBu-)Sc(u-H)(PMe )] 3  2  4  2  3  a  Crystal Radius Difference b  0  a) The formal coordination number at the metal centre. b) The effective ionic radius of the metal for that oxidation state and CN.  ;  c) The difference between the M-P bond length and the crystal radius.  The metal-phosphorus bond lengths of all of the crystallographically characterized complexes have been tabulated in Table 1.3; included in the table is the crystal radius for the particular metal in the appropriate oxidation state and coordination number. In the column labelled "Difference", the cation radius has been subtracted from the M—P bond length.  The wide range of values thus obtained  demonstrates that the variation in Ln—P bond length is not due to just the cation radius. Clearly the steric influence of the various other ligands about the metal has a large effect on the M—P interaction.  7  1.3 Phosphine Complexes of Hafnium and Zirconium  In recent years, the phosphine donor has been recognized as a suitable ligand for hafnium and zirconium as evidenced by numerous publications in this field.  8  However, by the end of 1979 (when work from this laboratory on early metal phosphine complexes was started) there were only 13 literature reports of such complexes, half of which were published in 1979. Table 1.4 lists the synthesis of these compounds in chronological order.  The simple dppe adducts of ZrCL^ and HTCI4, reported in 1965, were the first 28  phosphine derivatives of these metals. Seven years later it was shown  29  (via N M R  spectroscopy) that tetrabenzyl-zirconium and -hafnium formed an adduct with PMe3. In 1974, PPh3 and dppe were reported to be capable of displacing THF from 30  PhZrCl (THF) to give PhZrCl (THF)(PPh ) or PhZrCl3(dppe). In 1977, the small 3  3  3  basic PMe3 ligand was shown  31  3  to bind to Zr(II) by displacing one of the Tt-acceptor  CO ligands from Cp2Zr(CO)2 to form Cp2Zr(CO)(PMe3), while in 1978 it was demonstrated  32  that PF3 would displace N2 from [Cp*2Zr(N2)]2(M--N2) to give  [Cp*2Zr(PF3)]2(|i-N2). There were six publications in 1979 on a wide variety of compounds, demonstrating that the phosphine ligand could stabilize complexes in the +4, +3, +2 and 0 oxidation states. Clearly, the phosphine donor can be an excellent ligand for these metals no matter what the metal oxidation state.  In fact, the  phosphine donor is no longer an uncommon ligand for zirconium, and it is often used to stabilize low-valent complexes.  8  Table 1.4: Phosphine Complexes of Hafnium and Zirconium Prior to 1980. Year ef-  Synthesis  Complex  R  MX4(dppe): M = Hf, Zr; X = CI, Br M X 4 + dppe + P M e (in situ)  M(CH C H5) (PMe3): M = Zr, Hf  M(CH C H )  PhZrCl (THF)(PPh )  PhZrCl (THF) + PPH  PhZrCl (dppe)  P h Z r C l ( C H C N ) + dppe  2  6  4  3  2  3  6  5  4  3  3  3  3  3  3  3  1965  28  1972  29  1974  30  2  Cp* Zr(H) (PF )  C p * Z r ( H ) + P F (in situ)  !  Cp Zr(CO)(PMe )  C p Z r ( C O ) + PMe  197731  2  2  3  2  2  3  2  2  3  2  3  [Cp* Zr(PF )] (u-N )  [Cp* Zr(N )] (u-N ) + 2 P F  ZrCl4(dmpe)  ZrCl4 + 2 dmpe  2  3  2  2  2  ZrH(n,5-C H )(dmpe) 6  2  7  2  2  2  3  976  33  1978  32  1979  34  ZrCl (dmpe) + C6Hg + 2 Na/Hg 4  2  2  [Zr(Ti4-C H ) (dmpe)] (dmpe)  ZrCU(dmpe) + C H 6 + 2 Na/Hg  Zr(ri4-C H ) (dmpe)(PMe )  [Zr(ri4-C H ) (dmpe)] (dmpe)  ( C H ) M ( P M e ) : M = Hf, Zr  Toluene + P M e + Metal (g) at -196 ° C  1 9 7 9  Cp ZrL : L  Cp Zr(H)R + L  197936  4  4  7  8  6  6  2  2  4  3  2  2  2  2  = dmpe, dppe,  2  2 PPh Me, 2 PPhMe 2  2  Cp Zr(PPh Me) + C O 2  4  L = PPh Me, PPhMe 2  2  2  Cp ZrL + A  [CpZr(L)(u.-Til:Ti5-C5H )] :  2  2  2  2  [Zr(Ti -C H ) (dmpe)] (CO)  [Zr(Tt -C H ) (dmpe)] (dmpe)  [Zr(tl4.c H ) (dmpe)]  [Zr(Ti -C H6) (dmpe)] (CO)  4  6  4  2  6  4  2  2  4  2  6  2  2  3  HfCl [(Cl)CNBut](dppe) 3  2  4  2  3  6  + CO  2  2  2  2  1979  37  + vacuum  + L  3  Cp Hf(CO)L: L = PPh , PMe , P F 2  6  4  2  L = PMe , PMe Ph, P(OMe) 3  4  [Zr(ri4-C H ) (dmpe)]  [Zr(Ti4-C H ) (dmpe)] (L): 4  35  2  2  4  +2 L  2  2  Cp Zr(PPh Me)(CO) 2  2  3  3  2  6  4  3  Cp Hf(CO) + L 2  1979  2  {HfCl [(Cl)CNBut](CNBut)} + 2 dppe 1979 3  2  38  39  9  The first crystallographically characterized phosphine complexes of zirconium and hafnium were reported in 1980 and 1981.  The synthesis of  ZrH(rj 5  CgHn)(dmpe)2 was achieved via the reduction of ZrCl4(dmpe)2 with Na/Hg in the presence of 1,3-cyclooctadiene.  40  The hafnium(O) complex, Hf(C4H6)2(dmpe), was  synthesized by the reaction of H f C U with two equivalents of [Mg(C4H.6)(THF)2]n tithe presence of dmpe.  41  Since then, at least 35 zirconium and 7 hafnium complexes  containing phosphorus donors have been characterized by X-ray crystallography. From this data, the average M—P bond-length is 2.75 A in a range that spans from 2.972 (2) A for Zr(CH SiMe3) dmpe 2  4  42  to 2.619 (1) A for Cp Zr(CO)[P(OMe) ] 3. 4  2  3  There does not appear to be any correlation between bond length and metal oxidation state.  M = Hf, Zr Figure 1.2:  Some recently characterized group 4 phosphine complexes (left to right  references 44, 45 and 46).  More recently, the phosphine donor has been used to stabilize some interesting and unusual complexes (Figure 1.2).  The zirconocene fragment has been  stabilized by the coordination of two PMe3 ligands; crystallographic characterization of this complex reveals a very short Zr—P bond length of 2.64 A .  4 4  Benzyne has also  been trapped on the zirconocene fragment ; it was synthesized by the thermolysis of 45  10 Cp2ZrPb.2 i n the presence o f excess PMe3. The reduction o f M C l 4 ( T H F ) 2 , M = H f , Z r , with potassium napthalenide i n the presence o f trmpe, followed by the addition o f C O , led to the unique zero-valent c o m p l e x e s  shown i n Figure 1.2.  46  Numerous other  examples are given i n reference 8.  1.4 Summary of Previous Work from Our Laboratory  This summary of early metal amido-diphosphine complexes is based on four full journal p a p e r s , theses.  53,54  4 7 , 4 8 , 4 9  *  two journal communications,  5 0  51,52  and two M.Sc.  In 1979, the synthesis of a new six-electron, hybrid ancillary ligand was  developed which contained both an amido donor and two phosphine donors in a chelate array (Scheme 1.1).  55  Scheme 1.1 Me Si CI  Me Si  2  H  2  Me .Si^  3 LiPR ; R = Me, PH, Bu* 2  \l  CI  2 LiPPh  Me? Si  Me Si  f O  2  2  Me Si  2  I  2  JR,  LiBu  x  -(2 LiCl)  p  h  p  ^  rW  -(Butane)  The choice of ligand donors was deliberate and based on a number of simple observations: i) the amide donor was an excellent ligand for early transition metals in  11 high oxidation states; ii) the phosphine donor was considered to be the ligand of choice for low oxidation state late transition metals; iii) amide complexes of the late transition elements were rare; iv) phosphine complexes of the early transition metals were also rare; and v) the choice of ancillary ligand will often dictate the type of chemistry that occurs at a particular metal centre. What these five points indicate is that a ligand that incorporates both of the above donor types should be able to stabilize most metals in a variety of oxidation states and this could result in the synthesis of some unusual complexes (i.e., early metal phosphine complexes or late metal amides).  Such complexes might display unique reactivity patterns as the  ancillary ligand arrangement at the metal will be different from the more common sixelectron donor,  (C5H5)-  or (CsMes)-. As it is quite simple to vary the substituents at  the phosphine donor (Scheme 1.1), this ligand also displays a synthetic flexibility that makes available a variety of ligands with different stereo-electronic properties.  The reaction of two equivalents of LiN(SiMe2CH2PR-2)2 (R = Me or Ph) with either ZrCl4 or HfCU gave the six-coordinate derivatives shown in Scheme 1.2. Each ligand is only bound in a bidentate fashion and the metals are so sterically crowded that the chlorides would not react with Grignard or organolithium reagents.  47  As the bis(ligand) complexes were so unreactive, mono(amido-diphosphine) complexes were investigated (Scheme 1.2). Their syntheses were achieved by the addition of one equivalent of the lithium-amide to hafnium or zirconium tetrachloride; for the complexes with methyl groups at phosphorus long reaction times and high dilution were found to be necessary.  48  12  Scheme 1.2 MCI + 2 LiN(SiMe CH PR )2 4  2  2  MCI + LiN(SiMe CH PR2)2  2  4  toluene 1—5 days  -(2 LiCl)  EtpO  2  -(LiCl)  MCl2[N(SiMe2CH PR2)2]2  MCI [N(SiMe2CH2PR ) ]  M = Hf, Zr R = Me, Ph  M = Hf, Zr R = Me, PH, Bu  2  3  ^ \ — SiJ  M e P ' C^ \: Z r C.....>SiMe CH PMe 2  M e  2  2  * C/ P  CI  2  ^NSiMe CH PMe  •Sr  Me  2  2  \ 2  2  \  N R  Cl^  /  | N  2  l  MeoSi  /  Hi  CI  2  \ \  N  „ / /y  CI  £1  \ / Zr—CI  MfiMes2 Si'ni CI  PH  2  2  mer-  facX-ray Structures  These mono(amido-diphosphine) compounds were found to be quite reactive and a series o f derivatives were prepared.  H f C l 3 [ N ( S i M e 2 C H 2 P M e 2 ) 2 ] was  converted to Hf(BH4)3[N(SiMe2CH2PMe2)2L which i n turn was transformed into either the binuclear bridging trihydride Hf2(BH4)3[N(SiMe CH2PMe2) ]2(M--H)3 2  2  or  the dimeric bridging tetrahydride H f 2 ( B H 4 ) 2 [ N ( S i M e 2 C H 2 P M e 2 ) 2 J 2 ( ^ - H ) 4 , depending on the reaction conditions used (Scheme 1.3). 49  51  13  Scheme 1.3 LiBH  HfCl3lN(SiMe CH PMe )2l 2  2  2  •  4  Toluene  Hf(BH ) [N(SiMe CH PMe ) ] 4  3  2  NMe 5 days 2  4  3  2  2  2  2  2  3  3  3  2  3  -(H BNMe ) 3  A  2  3  H BSMe NMe  2  -(H BNMe )  3  Hf (BH ) [N(SiMe CH PMe ) ] (u-H)  2  Hf (BH ) [N(SiMe2CH PMe ) ] (u-H) 2  4  2  2  2  2  2  4  3  series of fluxional trimethyl complexes has also been synthesized.  MCl3[N(SiMe CH PR2)2] 2  2  (M = Hf, Zr;  R = Me, Pr', But)  r e a c t s  w  i h t  three  equivalents of MeMgCl to yield MMe3[N(SiMe2CH2PR )2l- A l l of these molecules 2  are fluxional and their N M R spectra display only one type of methyl resonance even when recorded at -90 °C. Phosphine dissociation of one arm of the amido-diphosphine ligand to generate a five-coordinate intermediate is a possible rationale for the observed spectra.  53  As the amido-diphosphine ligand should be capable of stabilizing a low-valent zirconium or hafnium complex, a series of butadiene complexes were synthesized. Thus, reaction of colourless MCl3[N(SiMe2CH2PR2)2l  with "magnesium butadiene"  yields the coloured diene complexes MCl(r) -C4H6)[N(SiMe2CH2PR2)2] (orange, M 4  = Hf; red, M = Zr). The zirconium complexes can also be obtained by Na/Hg reduction of the trichloride in the presence of excess butadiene. A l l of these compounds can also be further derivatized by metathesis of the remaining chloride with organolithium reagents (Scheme 1.4).  As seen with bis(cyclopentadienyl) group 4 diene complexes,  14 the M C l ( r i - C 4 H 6 ) [ N ( S i M e 2 C H 2 P R 2 ) 2 ] compounds are also fluxional. However, 4  they undergo a fundamentally different type of process. The fluxional behaviour for Cp2M(diene) compounds has been described as an "envelope flip" mechanism with 56  inversion of the diene unit occurring via the a -7i resonance structure shown below. 2  The diene compounds incorporating the amido-diphosphine ligand display a variable temperature N M R behaviour that is best rationalized by a diene rotation process. This diene rotation, as well as analysis of the X-ray crystal structure data, indicate that the r| -7t resonance form is an acceptable description of the diene-metal bonding 4  interaction.  50  Scheme 1.4  15  Scheme 1.5  pVelimination  T  The hafnium complexes, HfCl(rj -C4H )[N(SiMe2CH2PR )2] R = Me, Pr , 4  6  2  1  were also found to undergo a unique carbon-carbon coupling reaction when an allyl moiety was substituted for the remaining chloride (Scheme 1.5). For the derivative with methyl groups at phosphorus, the allyl-diene complex displayed N M R spectra in  16  accord with a complex that contained a rotating diene and an allyl unit undergoing synanti exchange. Over a period of days this complex slowly converted to the coupled product. The derivative with the bulkier isopropyl groups at phosphorus underwent the coupling reaction in about one hour. Scheme 1.5 shows two possible mechanisms for arriving at the observed allyl-diene coupled product. the analogous Cp*2M(diene)(allyl)  57  52  It is interesting to note that  and Cp2M(diene)(allyl)  58  complexes do not  undergo this reaction and demonstrate again how a change in the ancillary ligand can affect the observed chemistry. 1.5 The Scope of this Thesis  Chapters 2 and 3 deal with mono(amido-diphosphine) complexes and bis(amido-diphosphine) complexes of lanthanum, yttrium and lutetium. The synthetic strategy used is a continuation of the methodology described above. In order to obtain phosphine complexes of the lanfhanoidst, substitution of a chloride for an amido ligand containing pendant phosphine arms was expected to result in isolable lanthanoidphosphorus complexes.  The two basic target molecules are mono(amido-  diphosphine) complexes and bis(amido-diphosphine) complexes (Figure 1.3). The systematic synthesis and study of a variety of these complexes with different substituents at phosphorus were undertaken and the results are described in chapters 2 and 3. The choice of L a , Y + 3  + 3  and L u  + 3  as the cations to work with was deliberate.  All three metals are diamagnetic in their common +3 oxidation state, thus facilitating N M R spectroscopic studies.  In addition, their collective radii span that of the  lanthanide series. Both of these features make complexes of these metals excellent model compounds for the whole lanthanide series.  t Due to their similar physicochemical properties, Y, La and the lanthanide metals shall be referred to as lanthanoids.  17  mono(ligand)  bis(ligand)  Figure 1.3: Two target lanthanoid phosphine complexes.  The initial goal of this work was first to prove that lanthanoid complexes containing M—P bonds could be isolated, then examine the stereochemistry of the resulting complexes and determine the nuclearity of the complexes (i.e., monomers or oligomers). After these points had been addressed, the organometallic chemistry was to be investigated to see if the incorporation of the amido-diphosphine ligand induced new kinds of reactivity at lanthanoid-carbon bonds.  Chapters 4 and 5 deal with some chemistry of amido-diphosphine complexes of hafnium and zirconium. Chapter 4 is a continuation of the study of the unique allyldiene coupling reaction described earlier. The proposed mechanism for this coupling reaction involves two intermediate complexes; therefore, an investigation to look for evidence indicating such species was initiated.  This coupling has also been  investigated using the zirconium diene complexes with allyl-MgCl and 1-methylallylMgCl.  The chemistry in Chapter 5 is a result of the continuing investigations into the possible stabilization of lower oxidation state zirconium(amido-diphosphine)  18  complexes. This chapter describes the discovery and characterization of an unusual side-on bound dinitrogen zirconium complex, synthesized via the reduction of ZrCl3[N(SiMe2CH-2PPr 2)2] in the presence of dinitrogen. i  1.6  References McAuliffe, C. A. In Comprehensive Coordination Chemistry, Wilkinson, G.; Gillard, R. D.; McCleverty, J. A . (eds.), Pergamon Press: London, 1987, Vol 2, 989. Collman, J. P.; Hegedus, L. S.; Norton, J. R.; Finke, R. G. Principles and Applications of Organotransition Metal Chemistry, University Science Books: California, 1987, 66-72. Huheey, J. E. Inorganic Chemistry, 3 " ed.; Harper and Roe: New York, 1978; ra  527-534. a) Knowles, W. S. Acc. Chem. Res. 1983,16, 206. b) Haggin, J. Chem. Eng. News, 1990, May 7, 58. Davies, S. G. Organotransition Metal Chemistry: Applications  to Organic  Synthesis, Pergamon Press: Toronto, 1982, pp. 326-330. a) Nixon, J. F.; Pidcock, A . Ann. Rev. NMR Spec. 1969,2, 345. b) Garrou, P. E. Chem. Rev. 1981, 57, 229. c) Meek, D. W.; Mazanec, T. J. Acc. Chem. Res.  1981,14, 266. McAuliffe, C. A.; Levason, W. S. Phosphine, Arsine and Stibine Complexes of the Transition Elements, Elsevier: Amsterdam, 1979, 72. Fryzuk, M. D.; Haddad, T. S.; Berg, D. J. Coord. Chem. Rev., 1990, 99, 137. Ahrland, S.; Chatt, J.; Davies, N. R. Quart. Rev., Chem. Soc. 1958,12, 265. Pearson, R. G. /. Am. Chem. Soc. 1963, 85, 3533.  19  '  1 0  For a general discussion of the hard-soft acid-base theory see: Huheey, J. E. Inorganic Chemistry, 3 * ed.; Harper and Roe: New York, 1978; p. 312. rc  1 1  Greenwood, N. N.; Tranter, R. L. /. Chem. Soc, A. 1969, 2678.  1 2  Piers, W. P.; Shapiro, P. J.; Bunel, E. O.; Bercaw, J.E. Synlett. 1990,1, 74.  13  Hitchcock, P. B.; Lappert, M. F.; MacKinnon, I. A. /. Chem. Soc, Chem. Commun. 1988, 1557.  1 4  Bunel, E. E.; Schomaker, V.; Bercaw, J. E. unpublished results, 1988.  1 5  Shapiro, P. J.; Schaefer, W. P.; Bercaw, J. E. unpublished results, 1988.  1 6  Fryzuk, M. D.; Berg, D. J. unpublished results.  1 7  Fischer, R. D.; Fischer, H. J. Organomet. Chem. 1965, 4, 412.  1 8  Fischer, E. O..; Fischer, H. J. Organomet. Chem. 1966, 6, 141.  1 9  Bielang, G.; Fischer, R. D. /. Organomet. Chem. 1978,161, 335.  2 0  Tilley, T. D.; Andersen, R. A.; Zalkin, A. J. Am. Chem. Soc. 1982,104, 3725.  2 1  Schlesener, C. J.; Ellis, A. B. Organometallics, 1983, 2, 529.  2 2  Tilley, T. D.; Andersen, R. A.; Zalkin, A. Inorg. Chem. 1983, 22, 856.  2 3  Shinomoto, R. S. Energy Res. Abstr., 1985,10, Abstr. No. 10165; Chem. Abstr., 1985,103, 80844m.  2 4  Schumann, H.; Reier, F-W.; Palamidis, E. J. Organomet. Chem. 1985, C30.  297,  20  2 5  Stults, S.; Zalkin, A . Acta Cryst., C43,1987, 430.  2 6  Brennan, J. G.; Stults, S.; Andersen, R. A.; Zalkin, A. Organometallics, 1988, 7, 1329.  2 7  Shannon, R. D. Acta Cryst., Sect. A, 1976,32, 1706.  2 8  Ray, T. C , Westland, A. D. Inorg. Chem. 1965,4, 1501.  2 9  Felton, J. J., Anderson, W. P. /. Organomet. Chem. 1972,36, 87.  3 0  Clarke, J. F.; Fowles, G. W. A.; Rice, D. A. J. Organomet. Chem. 1974, 76, 349.  3 1  Demersemen, B.; Bouquet, G.; Bigorgne, M. /. Organomet. Chem. 1977,132, 223.  3 2  Manriquez, J. M.; McAlister, D. R.; Rosenberg, E.; Shiller, A. M.; Williamson, K. L.; Chan, S. I.; Bercaw, J. E. J. Am. Chem. Soc. 1978,100, 3078.  3 3  Manriquez, J. M.; McAlister, D. R.; Sanner, R. D.; Bercaw, J. E. /. Am. Chem. Soc. 1976, 98, 6733.  3 4  Datta, S.; Wreford, S. S.; Beatty, R. P.; McNeese, T. J. J. Am. Chem. Soc. 1979,101, 1053.  3 5  Geoffrey, F.; Cloke, N.; Green, M. L. H. /. Chem. Soc, Chem. Commun. 1979, 127.  3 6  Gell, K. I.; Schwartz, J. /. Chem. Soc, Chem. Commun. 1979, 244.  3 7  Beatty, R. P.; Datta, S.; Wreford, S. S. Inorg. Chem. 1979,18, 3139.  3 8  Sikora, D. J.; Rausch, M. D.; Rogers, R. D.; Atwood, J. L. /. Am. Chem. Soc. 1979,101, 5079.  21  3 9  Behnam-Dehkordy, M.; Crociani, B.; Nicolini, M.; Richards, R. L. /. Organomet. Chem. 1979,181, 69.  4 0  Fischer, M. B.; James, E. J.; McNeese, T. J.; Nyburg, S. C ; Posin, B.; WongNg, W.; Wreford, S. S. /. Am. Chem. Soc. 1980,102, 4941.  4 1  Wreford, S. S.; Whitney, J. F. Inorg. Chem. 1981,20, 3918.  4 2  Cayias, J. Z.; Babaian, E. A.; Hrncir, D. C ; Bott, S. G.; Atwood, J. L. J. Chem. Soc, Dalton Trans. 1986, 2743.  4 3  Erker, G.; Dorf, U.; Kruger, C ; Angermund, K. J. Organomet. Chem. 1986,301, 299.  4 4  Kool, L. B.; Rausch, M. D.; Alt, H. G.; Herberhold, M.; Honold, B.; Thewalt, U. /. Organomet. Chem. 1987,320, 37.  4 5  Buchwald, S. L.; Watson, B. T.; Huffman, H. C. /. Am. Chem. Soc. 1986,108, 7411.  4 6  Blackburn, D. W.; Chi, K. M.; Frerichs, S. C ; Tinkham, M. L.; Ellis, J. E. Angew. Chem., Int. Ed. Engl. 1988, 27, 437.  4 7  Fryzuk, M. D.; Williams, H. D.; Rettig, S. J. Inorg. Chem. 1983, 22, 863.  4 8  Fryzuk, M. D.; Carter, A.; Westerhaus, A. Inorg. Chem. 1985,24, 642.  4 9  Fryzuk, M. D.; Rettig, S. J.; Westerhaus, A.; Williams, H. Inorg. Chem. 1985, 24,4316.  5 0  Fryzuk, M. D.; Haddad, T. S.; Rettig, S. J. Organometallics, 1989, 8, 1723.  5 1  Fryzuk, M. D.; Williams, H. Organometallics, 1983,2, 162.  5 2  Fryzuk, M. D.; Haddad, T. S.; Rettig, S. J. Organometallics, 1988, 7, 1224.  22  Carter, A. M.Sc. Thesis, U B C , 1985. Haddad, T. S. M.Sc. Thesis, U B C , 1987. a) Fryzuk, M. D.; MacNeil, P. A . J. Am. Chem. Soc. 1981,103, 3592. b) Fryzuk, M. D.; MacNeil, P. A ; Rettig, S. J.; Secco, A . S.; Trotter, J. Organometallics,  1982,1, 918. c) Fryzuk, M. D.; Carter, A.; Westerhaus, A.  Inorg. Chem. 1985, 24, 642. a) Erker, G.; Kruger, C ; Muller, G. Adv. Organometal. Chem. 1985,24, 1. b) Yasuda, H.; Nakamura, A. Acc. Chem. Res. 1985,18, 120. Blenkers, J.; de Liefde Meijer, H. J.; Teuben, J. H. /. Organomet. Chem. 1981, 218, 383. a) Erker, G.; Berg, K.; Kruger, C ; Muller, G.; Angermund, K.; Benn, R.; Schroth, G. Angew. Chem., Int. Ed. Engl. 1984,23, 455. b) Erker, G.; Berg, K.; Benn, R.; Schroth, G. Angew. Chem., Int. Ed. Engl. 1984, 23, 625.  23 CHAPTER 2:  BIS(AMIDO-DIPHOSPHINE) COMPLEXES OF  LANTHANUM, YTTRIUM AND LUTETIUM  2.1  Introduction  This chapter is devoted to the chemistry of bis(amido-diphosphine) complexes of lanthanum, yttrium and lutetium. The synthesis and characterization of a series of such phosphine complexes with variation of both the metal and the type of phosphorus donor are described: MCl[N(SiMe2CH2PR2)2k R = Me, M = Y, La, Lu (a series); R = Ph, M = Y, La (b series) and R = Pr', M = Y (c series).''' In addition, the synthesis of some hydrocarbyl derivatives for the a series, their characterization, and the thermolysis of these organometallic species are presented.  Lanthanoid hydrocarbyl complexes are rare and only recently have general procedures for their isolation been developed.  1  In fact, a 1956 publication by  Wilkinson and Birmingham states : "it seems to be fairly certain that alkyl and aryl 2  derivatives of scandium, yttrium, lanthanum and the rare earth elements either do not exist or have an existence so transitory that they cannot be isolated." Generally speaking, lanthanoid hydrocarbyl complexes are highly reactive, often unstable species, but given the right ancillary ligand arrangement about the metal such compounds can be isolated.  A number of interesting hydrocarbyl lanthanoid complexes have been recently synthesized; a description of three such complexes will demonstrate their reactivity. t  Throughout this thesis, the subscripts a-d shall be used to denote the type of amido-  diphosphine ligand [N(SiMe2CH2PR2)2]" in the complex: a, R = Me; b, R = Ph; c, R = Pr'; d, R = Bu . l  24 The lutetium complex Cp*2LuCH3(OEt2) was the first compound to directly model olefin insertion into a metal-alkyl bond, the lanthanide model for Ziegler-Natta polymerization.  This lutetium methyl complex is extremely reactive and will  3  polymerize ethylene even at -90 ° C . It was the first organometallic complex for which a well characterized reaction with methane was demonstrated and it also provided the first example of (3-methyl elimination at a metal centre. (Ln  = L u , Er, Y ;  R  = H , Me)  The [(CsH4R)2LnH(THF)]2  4  complexes, obtained by hydrogenolysis of  (C5H4R)2Ln(Bu )(THF), were the first fully characterized organometallic lanthanide l  hydrides , and provided the opportunity to study the reactivity of the lanthanide5  hydride moiety in discrete well defined complexes. The Cp*2ScR complex has been 6  7  used to generate the highly reactive deuteride Cp*2ScD which, under a D2 atmosphere, catalyses C5(CD )5H. 3  8  multiple H/D exchange converting  C s ( C H 3 ) 5 H into  The isotopically labelled C s ( C D 3 ) 5 H can easily be converted to  perdeuterio LiCp* and used as a synthon for deuterium labelled transition metal Cp* complexes.  2.2  Synthesis  of Bis(amido-diphosphine)  Complexes  The synthesis of bis(amido-diphosphine) complexes is relatively straightforward.  Addition of two equivalents of the amide salts [ N ( S i M e 2 C H 2 P R 2 ) 2 ] " to  YCI3, L.UCI3 or L a C l 3 in T H F generates the desired compounds (Equation 2.1). THF MCI + 2M'[N(SiMe CH PR ) ] 3  2  M' = K or Li  2  2  • MCI[N(SiMe CH PR ) ]  2  2  I LiCI^  M  = Y  :  R  =  M  R R M = Lu: R M = La: R R  2  2  e  = = = = =  1  Ph Pr Me Me Ph j  2  2  a  1b 1c 2a 3a 3b  [2.1]  25 With the smaller cations L u  + 3  and Y  + 3  (seven-coordinate ionic radii of 1.06 A  and 1.10 A) either amide salt will generate good yields of the bis(ligand) complexes. 9  However, the larger L a  + 3  (ionic radius of 1.24 A)  9  does not react with the lithium  amides; long reaction times with the potassium salts are required to obtain the phosphine complexes.  Scheme 2.1  Lu 8a La 9a  The yttrium and lutetium bis(ligand) complexes MCl[N(SiMe2CH2PMe2)2]2, l a and 2a, can be further derivatized to generate hydrocarbyl complexes MR[N(SiMe2CH2PMe2)2]2» 4a-6a, which can be isolated and stored under nitrogen indefinitely as crystalline solids.  These hydrocarbyl compounds are thermally  unstable in solution and undergo a clean cyclometallation reaction by abstracting a  26 PCH2Si-methylene hydrogen to generate the cyclometallated product 7a or 8a v i a loss  o f R — H (Scheme 2.1).  F o r the c o r r e s p o n d i n g lanthanum  complex  L a C l [ N ( S i M e 2 C H 2 P M e 2 ) 2 l 2 » 3a, reaction with p h e n y l l i t h i u m yielded o n l y the cyclometallated complex 9a; the lanthanum-phenyl derivative could not be observed at room temperature. The reaction of L i C H 2 S i M e 3 with la or 3a leads directly to the cyclometallated products 7a and 9a.  It is noteworthy that using T H F as a solvent i n any o f the aforementioned reactions has not resulted in formation o f any T H F adducts. In fact, the N M R spectra of the M C l [ N ( S i M e 2 C H P M e 2 ) 2 ] 2 compounds obtained i n T H F / C 6 D 6 or C 6 D 6 are 2  identical. This perhaps indicates that these compounds are coordinatively saturated.  2.3  NMR Characterization and Fluxional Behaviour  A l l o f the seven-coordinate chloro and hydrocarbyl complexes are highly fluxional  as e x p e c t e d .  1 0  F o r those compounds w i t h methyl substituents at  phosphorus (a-series) the amido-diphosphine ligand displays three resonances i n each o f the room temperature ^ C p H } and * H N M R spectra (i.e., the phosphorus methyl hydrogens and carbons, the methylene protons and carbons, and the s i l y l methyl hydrogens and carbons respectively) as shown i n Figure 2.1.  A t low  temperatures, the * H N M R spectra o f the chloro derivatives la, 2a and 3a, are uninformative as broad signals are observed right down to -95 °C. However, the low temperature * H N M R spectra o f the phenyl complexes M P h [ N ( S i M e 2 C H 2 P M e 2 ) 2 l 2 . 4a and 6a, display proton resonances for four different silyl methyl, four phosphorus methyl and four methylene groups, while the low temperature ^ C p H } N M R spectra show four s i l y l methyl, four phosphorus methyl and two methylene carbon resonances (Figure 2.2).  27 PCH  8.2  7.8  i  C  H  3  SiCH P  Hm  8 6  S  3  2  H  c  7.4  PPM  1.2  0. 8  0.4  PCH  3  0.0  PPM  SiCH,  SiCH P 2  Cm C  r  LL jI 145  I I I  II  140  I I I  II  135  I I I  II  130  I I I  II  I I  II  125 PP«5  I I I  II  I I I  20  II 15  I I I [ I I I I  10  II  II  5 PPM  Figure 2.1: 300 MHz *H NMR spectrum (top, in C 6 D ) and 75.4 MHz ^C{ H) l  6  NMR spectrum (bottom, in C6D5CD3) of Y(Ph)[N(SiMe CH PMe2)2]2 recorded at 2  2  room temperature. Solvent peaks are marked with an asterisk.  28  PCH, SiCH  ?  Hm SiCH P  H  8.6  8 2  7.8  7.4  [f \J  2  7 . 0 PPM6  1.2  0.8  PCH  * cm  SiCH P 2  V 0-. 4  "0.0  3  SiCHs  SiCH P 2  J I I I | I I I I | I I II  145  140  Figure 2.2:  135  Ul  | I I II  130  | I I I  I I I I [ I I I I | I II  125 P P « 5  20  15  300 M H z *H N M R spectrum (top) and 75.4 M H z  I | I I I I | I I I  10  13cpH}  5PPM NMR  spectrum (bottom) of Y(Ph)[N(SiMe CH PMe )2]2 in Q D 5 C D 3 recorded at -49 ° C . 2  2  Solvent peaks are marked with an asterisk.  2  29  S i m i l a r results are obtained from the 3 1 p { l H } N M R spectra.  T h e spectra  obtained at room temperature show only one phosphorus resonance (a doublet for the yttrium derivatives) indicating four equivalent phosphines i n fast exchange, while at l o w temperature two phosphorus environments c a n be discerned.  F o r the chloro  derivatives la-3a, only the yttrium complex la shows an analyzable pattern (Table 2.1) while the others show two poorly resolved signals. However, the yttrium- and lutetium-phenyl complexes 4a and 6a display w e l l resolved spectra ( A A ' B B ' for L u and A A ' B B ' X for spin 1/2 Y ) . The have been simulated;  3 1  P { H } N M R spectra obtained at low temperature 1  the experimental and simulated patterns f o r 4a and 6a are  shown i n Figures 2.3 and 2.4, while the coupling constants are tabulated i n Table 2.1. Of the three standard seven-coordinate geometries (pentagonal b i p y r a m i d , capped octahedron or capped trigonal prism), assigning these complexes a pentagonal bipyramidal geometry generates the most reasonable structures.  T h e three possible  geometrical isomers which satisfy the observed N M R data are shown i n Figure 2.5. The amido-diphosphine ligands are fac-fac (C2 symmetry where the phosphine donors of each ligand are cisoid), mer-mer (C2 symmetry where the phosphine donors o f each ligand are transoid), or fac-mer (C  s  symmetry where the phosphine donors o f one  ligand are transoid and the other are cisoid). A t this point there is no definitive way to distinguish among these possibilities, but the mer-mer arrangement o f the ligands is the most reasonable as it w o u l d have the least strain induced by the planar Y — N R  2  moiety. In an ideal pentagonal bipyramid the P — M — P bond angle would be 144° for a mer ligand and 72° for a fac ligand. Further evidence indicating the preference for this ligand to bind i n the mer fashion comes from some previous X-ray crystallographic results. F r o m twelve structures the average P — M — P angle is 141°, the smallest P— M — P angle ever o b s e r v e d  11  for this ligand is 102° (in H f C l 3 [ N ( S i M e 2 C H 2 P M e 2 ) 2 ] )  and the two yttrium structures which have been solved (vide supra) have this angle between 148 and 160 °.  30  Figure 2.3: 121 M H z 31p{lH} N M R spectrum of Y(Ph)[N(SiMe CH PMe2)2]2 in 2  2  C6D5CD3 recorded at -49 ° C (top) and a simulation (bottom) using Bruker PANIC software. See Figure 2.5 and Table 2.1 for details.  31  Figure 2.4: 121 M H z 31p{lH} NMR spectrum of Lu(Ph)[N(SiMe2CH PMe2)2]2 in 2  C6D5CD3 recorded at -59 ° C (top) and a simulation (bottom) using Bruker PANIC software. See Figure 2.5 and Table 2.1 for details.  32  fac, mer Figure 2.5: Three possible structures based on a pentagonal bipyramidal geometry for MR[N(SiMe2CH2PMe2)2]2 complexes in the low temperature limit. The NMR spin system in the pentagonal plane is also shown.  31  P{ H} 1  33  It is noteworthy that the magnitudes of the two bond phosphorus couplings (Jp-p) correlate with the assumed positions in the equatorial pentagonal plane in that 2  transoid are greater than cisoid couplings. These coupling constants also agree with previously reported Jp.p values of 5 3 to 80 Hz for trans disposed phosphines in the 12 2  Group 4 complexes, MR(ti -C H )[N(SiMe2CH2PMe2)2] (M = Hf, Zr; R = CI, Ph, 4  4  6  Np).  Table 2.1: Up.y and J .p Coupling Constants for MR[N(SiMe2CH PMe2)2]22  Coupling  2J  P  2  M=Y, R=Ph,» 4a +21.9  PA-P '  M=Lu, R=Ph, 6a b  ±19.6  M=Y, R=C1, l a C  ±18.0  A  2J  PA-PB  -6.3  -7.85  -2.0  2J  PA-PB-  +49.1  +70.75  +49.0  P -PB  +49.1  +70.75  +49.0  JP .-P . B  -6.3  -7.85  -2.0  JP .p . B  ±44.1  P -Y  36.5  —  52.3  P -Y  36.5  —  52.3  ^PB-Y  51.3  —  50.8  1JP ..  51.3  —  50.8  2J  A  2  A  2  B  1J  A  1J  A  B  Y  a) At - 4 9 ° C : 8 P  A  ±62.1  ±80.0  = 8 P « = - 4 3 . 6 ppm; 5 P = 8 P - = -48.8 ppm. A  B  B  b) At - 5 9 °C: 5PA  = 5PA- =  c) At - 9 0 ° C : 8 P  = 5 P ' = - 4 3 . 8 ppm; 8 P = 6 P - = -45.9 ppm.  A  A  -39.7 ppm; 8 P = 5 P - = - 4 6 . 4 ppm. B  B  B  B  34 To account for the observed fluxional behaviour of these phosphine complexes it is tempting to invoke pseudorotation or stereochemical nonrigidity, a known process for many seven-coordinate complexes in which no metal-ligand bonds are broken.  10  However, a simpler explanation is that these processes occur by a series of rapid equilibria involving dissociation of the phosphine arms of the tridentate ligands, rotation about the M—NR bond, followed by reassociation. The free energy of 2  activation, AG*, for the process that renders all four phosphines equivalent changes only slightly for the La (10 Kcal/mol) to Y (10.1 Kcal/mol) to Lu (9 Kcal/mol) series of MCl[N(SiMe2CH2PMe2)2l2  complexes.  For the phenyl derivatives,  M P h [ N ( S i M e 2 C H 2 P M e 2 ) 2 k M = Y and Lu, the AG* are also very similar, 11.5 Kcal/mol for yttrium and 11.0 Kcal/mol for lutetium.  When a more bulky ancillary ligand is coordinated to yttrium, the variable temperature NMR behaviour changes. For the complex which has the bulky, but less basic, phenyl groups at phosphorus, YCl[N(SiMe2CH2PPh )2]2 l b , the P{ H} 31  !  2  NMR spectrum recorded at +29 "C shows the expected doublet ^Jy-P = 39 Hz), indicating four equivalent phosphines. However, at -59 °C the spectrum clearly shows four different phosphorus environments. This spectrum has been simulated and both the observed and calculated spectrum along with the coupling constants are shown in Figure 2.6. Three of the phosphines are coordinated to the metal, as shown by the l  Jy-P coupling constants, while the fourth appears to be dangling freely in solution (a  sharp singlet which displays no couplings).  The complex with a six-coordinate  distorted octahedral geometry shown in Figure 2.6 is a possible structure for this compound.  An analogous six-coordinate species from the a-series compounds  M R [ N ( S i M e 2 C H P M e 2 ) 2 l 2 . la-6a, could be an undetectable intermediate in the 2  fluxional process which exchanges all four phosphine sites.  Figure 2.6:  121 MHz P{ H} NMR spectrum of YCl[N(SiMe CH PPh2)2]2 in 31  ]  2  2  C6D5CD3 recorded at -59 °C (top) and a spectral simulation using Bruker PANIC  software (below).  36  For  the lanthanum  complex  with  phenyl  groups  at phosphorus  LaCl[N(SiMe2CH2PPh2>2]2» 3b, the P { H ) N M R spectra are again different as an 31  1  equilibrium between two species is apparent (Figure 2.7). compound is present.  Above 80 ° C only one  It displays N M R spectra typical of the seven-coordinate  fluxional species: YCl[N(SiMe2CH2PR2)2]2, R = Me, Ph. However, below -40 ° C , a different complex is present, one that displays two uncoupled phosphorus environments which exchange with one another at higher temperature. Between +80 ° C and -40 ° C both complexes are observable. It is possible that a monomer/dimer equilibrium is occurring, the dimer being favored at low temperature.  That this  monomer/dimer behaviour is not observed for yttrium and lutetium could be due to the smaller size of these metals relative to lanthanum, as the larger lanthanum is capable of the eight coordination geometry that a chloride-bridged dimer would require. It is possible that the complex LaCl[N(SiMe2CH PMe2)2]2> 3a, also participates in such 2  an equilibrium. However, at the crucial temperatures where differentiation between the two species might be observed, the  31  P { H ) N M R spectra of this compound are 1  complex and only show broad lines; thus, no conclusions can be drawn. Molecular weight determinations show that 3a, 3b, and l a are monomelic in C^D^ at 20 ° C (at concentrations of 10 - 20 mg / mL).  37  | I M I  I  I M I | U I I  -10  Figure 2.7:  -12  I I I  I  I |  I I  -14  I  I  I I  I  I  I | I  -16  I I  I  I  I  I I  I  -18  | I  I I  I | I I  I  -20  I  ) U  ' I |  I I I  -22  I | I I I  I | I  -24  I I  I | I I I  I |  I I  I  -26  I | I I I I  | I I  I I | I I I I | I I I I | I I I I  -26 PPM  121 M H z 3lp{lH} N M R spectra of LaCl[N(SiMe CH PPh2)2]2 in 2  2  CD3C6D5 as a function of temperature. The actual concentration is unknown. impurity, HN(SiMe2CH2PPh2)2> is indicated with an asterisk.  An  38  It is interesting to note that for the complex with the bulky and very basic isopropyl phosphorus substituents YCl[N(SiMe2CH2PPr 2)2l2. lc. yet another type i  of temperature dependent behaviour is observed.  At room temperature a doublet  (Uy-p = 44 Hz) indicating four equivalent phosphines is observed in the  3 1  P{ H) 1  N M R spectra. This doublet appears to go through "coalescence" around -40 "C and at least three new resonances appear, two singlets and one doublet (*Jy-p = 89 Hz) at -80 ° C . A low temperature limit cannot be achieved in C 6 D 5 C D 3 (at lower temperatures further line broadening occurs) and therefore it is difficult to reconcile these results. No further work was done with this complex because its high solubility made purification difficult.  The cyclometallated complexes  7a-9a,  derived from the loss of R-H from the  hydrocarbyl complexes M R [ N ( S i M e 2 C H 2 P M e ) ] 2 (See Scheme 2.1) are also 2  2  fluxional. Although the lanthanum complex 9a does not reach a low temperature limit even at -100 ° C , at -29 ° C for yttrium and +20 ° C for lutetium, static  31  P{ H} NMR 1  spectra with four inequivalent phosphines are obtained (Figures 2.8 and 2.9, Table 2.2). At higher temperatures (T = -79 ° C for lanthanum, +65 ° C for yttrium and +90 ° C c  for lutetium) two of the phosphines exchange, while the metallated ligand remains rigid (AG* = 8.8 Kcal/mol for lanthanum (estimated), 15.3 Kcal/mol for yttrium and 16.3 Kcal/mol for lutetium) The simplest explanation for these observations is that in solution, the non-metallated ligand has phosphines which rapidly come on and off the metal. This enables these two phosphines to exchange coordination sites via rotation about the M—NR2 bond.  One end of the metallated ligand may be undergoing  dissociation-reassociation as well, but this is difficult to substantiate.  39 M&z  M&2  '1  I  I  I  I  I  I  I  I  Figure 2.8: i  1  I  -41.5  -34.5  -34.0  I I  I  I  I  I I  -42 0  I  I  I  I  I  I  1  I  I  -42.5  I  I  I  I I  I  I  I  -45.5  121 M H z 31p{lH} N M R spectrum (top) and simulation (bottom) of  Y[N(SiMe CHPMe )(SiMe CH PMe )][N(SiMe CH PMe ) ], 2  I I  -45.0  2  2  2  2  recorded at -29 °C. See Table 2.2 for details.  2  2  2  2  7a, in  CD C D 3  6  5  40  Figure 2.9:  121 M H z  31  P { H } N M R spectrum (top) and simulation (bottom) of J  L u[N(SiMe2 CHPMe )(SiMe CH PMe )][N(SiMe CH PMe2)2], ,  ,  recorded at -29 °C.  2  2  2  2  See Table 2.2 for details.  2  2  8a, in  CD C D 3  6  5  41 Table 2.2: Up.y and Jp.p Coupling Constants for 2  M [ N ( S i M e C H P R ) ( S i M e C H P R ) ] [N(SiMe2CH PR ) ]. 2  2  2  2  2  Coupling M=Lu, R=Me , 8a  2  M=Y, R=Ph , 7b c  b  7.9  13.45  12.2  29.3  18.46  2.2  Pl-P4  30.3  20.86  12.8  Jp -P 2  3  32.5  11.52  8.5  JP -P 2  4  9.4  8.20  0  JP -P  4  21.2  18.54  23.8  —  70.00  32.7  —  36.61  38.1  —  47.00  63.4  —  67.98  61.1  2 j  2j  2j  2  2  M=Y, R=Me , 7a  a  2  2  2  Pl-P  2  Pl-P  3  3  V Y  1  JP -Y 4  a) At +20 ° C : 8P1 = -38.6.ppm; 8P2 = -34.8 ppm; 6P3 = -36.9 ppm; 8P4 = -40.1 ppm. b) At -29 ° C : 5P1 = -42.0 ppm; 8P2 = -34.2 ppm; 8P3 = -41.9 ppm; 8P4 = -45.3 ppm. c) At -19° C: 8P1= -8.8 ppm; 8P2 = +0.4 ppm; 8P3 = -7.0 ppm; 8P4 = -14.8 ppm.  Addition of L i C H S i M e 2  3  to Y C l [ N ( S i M e C H P P h ) ] , l b , the yttrium 2  2  2  2  2  complex with phenyl groups at phosphorus, generates the ligand metallated complex Y[N(SiMe CHPPh )(SiMe CH PPh )][N(SiMe CH PPh ) ], 7b. 2  2  2  2  2  2  2  2  2  This compound  shows similar N M R spectra to those exhibited by 7a-9a (i.e., at low temperature a seven-coordinate complex with four inequivalent phosphorus resonances is observed, while at high temperature the two phosphines of the non-metallated ligand undergo chemical exchange).  The static spectra for 7a, 8a and 7b have been simulated; the  42  experimental and calculated spectrum for 7a and 8a are shown in Figures 2.8 and 2.9, while the coupling constants for all three complexes are listed in Table 2.2.  The  8 9  Y  N M R spectra of two yttrium complexes were also obtained.  The  spectrum of Y[N(SiMe2CHPMe )(SiMe2CH2PMe )][N(SiMe2CH PMe ) ], 7a, and 2  2  2  2  2  YCl[N(SiMe CH PMe2)2l2. l a . are shown in Figure 2.10. Both complexes display 2  2  ^ p . y couplings. Complex 7a shows an overlapping "doublet of doublet of triplets" pattern due to the coupling of two inequivalent and two equivalent phosphorus donors to the metal. Complex l a shows a much simpler five line pattern due to the coupling of four equivalent phosphines to the yttrium centre. observed in the ^ ^ H }  These couplings match those  N M R spectra.  3  Both l a and 7a resonate considerably downfield of aqueous 3 M YCI3 (the standard set at 0 ppm), l a at +449 ppm and 7a at +533 ppm. There are not many compounds for which  8 9  Y N M R data are available to compare. The first papers  13  published using this technique were on simple inorganic salts and demonstrated that such yttrium containing species resonate over a wide chemical shift range ( +150 to -130 ppm), display long relaxation times (about three minutes) and their chemical shifts are temperature and concentration dependant. More recently, a publication on 14  8 9  Y N M R spectra of some organometallic species reported the chemical shift range for  a variety of [ C p 2 Y R ] (n = 1, 2; R= CI, C H 3 , H) compounds to be between -371 ppm n  and +40 ppm. Another paper reports  15  the  8 9  Y chemical shifts of [H B(pz)2J3Y and 2  [ H 2 B ( 3 , 5 - M e 2 p z ) 2 l 3 Y to be +238.8 and +105.6 ppm. Taken together, these data demonstrate that the coordination of the amido-diphosphine ligand to yttrium results in a metal that is more deshielded than when a cyclopentadienyl or pyrazolylborate ligand is used. It is worth noting that the chemical shift of l a was found to be +449 ppm in both C6D5CD3 and in a THF/C6D5CD3 mixture.  43  Figure 2.10:  8 9  Y N M R spectra of l a (top, 19.6 MHz) in C D 3 C 6 D 5 / T H F and 7a  (middle, 24.6 MHz) in CD3C6D5.  The theoretical spectrum of 7a, based on the  couplings constants in Table 2.2, is also shown (bottom).  44  2.4  X-ray Crystal Structure Determination of  Y [ N ( S i M e C H P M e ) ( S i M e C H P M e ) ] [ N ( S i M e C H P M e ) ] , 7a 2  2  2  2  2  2  2  2  2  The molecular structure of 7a (Figure 2.11, Tables 2.3 and 2.4) is best described as a capped octahedron. The two nitrogens and the four phosphines form a distorted octahedron with the metallated carbon as the capping ligand. The low temperature P{!H} NMR spectrum is consistent with this structure and the atom 31  designations PI, P2, P3 and P4 in the crystal structure have been assigned to the 3lp{lH} N M R spectrum (Table 2.2). PI and P2, which belong to the metallated ligand, are the non-fluxional phosphines. As P2 is in a strained three-membered ring, and therefore in the most different chemical environment, its assignment was made on the basis of the most unusual chemical shift (-34.2 ppm). P2 also has the closest contact with the metal, therefore we would expect it to show the largest coordination contact shift. This then places PI at -42.0 ppm. The assignments of the fluxional P3 (at -41.9 ppm) and P4 (at -45.3 ppm) atoms are purely arbitrary as there is no definitive way of distinguishing between these atoms. Table 2.3: Selected Bond Lengths for i Y[N(SiMe CHPMe )(SiMe CH PMe )][N(SiMe CH PMe ) ], 7a.  1 2  2  2  2  2  2  2  2  2  Bond  Length (A)  Bond  Length (A)  Bond  Y—C2  2.65 (1)  Y—NI  2.256 (7)  Si4—C4  1.86 (1)  Y—P2  2.817 (3)  Y—N2  2.396 (7)  P2—C2  1.73 (1)  Y—PI  3.005 (3)  Si2—C2  1.84 (1)  PI—CI  1.80 (1)  Y—P3  2.896 (3)  Sil—CI  1.90 (1)  P3—C3  1.80 (1)  Y—P4  2.903 (3)  Si3—C3  1.91 (1)  P4—C4  1.80 (1)  Length (A)  45  Figure 2.11:  Chem 3 D ® core view (top) and O R T E P stereoview (bottom) of  Y [ N ( S i M e C H P M e ) ( S i M e C H P M e ) ] [ N ( S i M e C H P M e ) ] , 7a. 2  2  2  2  2  2  2  2  2  46  Table 2.4: Selected Bond Angles for Y [ N ( S i M e C H P M e ) ( S i M e C H P M e ) ] [ N ( S i M e C H P M e ) ] , 7a. 2  2  2  2  2  2  2  2  2  Bonds  Angle (deg)  Bonds  Angle (deg)  Pl-- Y - -P2  161.38 (9)  N l -- Y — N 2  165.2 (3)  Pl-- Y - -P3  85.24 (8)  P l - -Y—C2  134.3 (2)  Pl-- Y - -P4  86.5 (1)  P2--Y—C2  36.7 (2)  P2-- Y - -P3  106.2 (1)  P3--Y—C2  83.9 (2)  P2-- Y - -P4  90.0 (1)  P4--Y—C2  121.3 (2)  P3-- Y - -P4  150.2 (1)  N l -- Y — C 2  69.5 (3)  Pl-- Y - -NI  71.5 (2)  N2-- Y — C 2  125.2 (3)  P2-- Y - -NI  90.9 (2)  Y— -C2—P2  76.8 (4)  P3-- Y - -NI  106.7 (2)  Y— -P2—C2  66.5 (4)  P4-- Y - -NI  97.6 (2)  Y - -NI—Si2  101.0 (3)  Pl-- Y - -N2  94.4 (2)  Y - -C2—Si2  84.7 (4)  P2-- Y - -N2  102.6 (2)  Nl--Si2—C2  104.4 (4)  P3-- Y - -N2  75.6 (2)  Si2-—C2—P2  123.3 (6)  P4-- Y - -N2  76.6 (2)  The four phosphorus-yttrium bond lengths of 3.005 (3) A, 2.903 (3) A, 2.896 A (3) and 2.817 (3) A span a large bond length domain. reported  1 6  Y—P  bond  length  to  compare  There is only one other  with;  the  six  coordinate  Y [ O C B u 2 C H 2 P M e 2 ] 3 complex (ionic radius 1.040 A) has a Y — P bond length of l  3.045 (2) A.  The fact that the seven-coordinate complex 7a (ionic radius 1.10 A) has  47  shorter Y—P bond lengths indicates less steric congestion in 7a. Presumably, the short Y—P2 bond length of 2.817 A is due to the three-membered ring formed by the metallated carbon C2, yttrium and P2.  There are five X-ray crystal structures reported for lanthanide phosphine complexes. Their M—P bond lengths are: (CsH Me)3Ce(PMe3), 3.072 (4) A  1 7  4  (C H Me)3Ce[P(OCH )3CEt], 3.086 (3) A 5  4  2  1 8  ;  ; Nd[OCB t CH PMe ] , 3.154 (2) U  2  2  2  3  A ; (C Me ) YbCl(dmpm), 2.941 (3) A™; and Yb[N(SiMe ) ] (dmpe), 3.012 (4) 1 6  5  5  2  3  2  2  A . Based solely on ionic radii, one should expect seven-coordinate Y 3 (1.10 A) to 2 0  +  have shorter metal phosphorus bond lengths than ten-coordinate C e coordinate N d  + 3  (1.123 A), eight-coordinate Y b  + 3  + 3  (1.39 A), six-  (1.125 A) or six-coordinate Y b  + 2  (1.16 A). The average Y—P bond length in 7a of 2.93 A (for the three non-metallated phosphines) is indeed shorter, however, as was noted in the introduction (Section 1.2), the steric effects of the other ligands present play a large role in determining the Ln—P bond length.  The yttrium-carbon bond length of 2.65 (1) A is long for a yttrium rj-carbon bond. A typical bond length  21  is 2.47 A, for example, (CsMe5) YCH(SiMe3) has a 2  2  Y — C bond length of 2.468 (7) A. Complexes that contain bridging alkyls have much 22  longer Y — C bonds, e.g., [l,3-Me C5H ) Y(Lt-Me)] has Y-Me bond lengths 2  3  2  2  23  of  2.60 (1) and 2.62 (2) A, and [(C H ) Y(u-Me)] has a Y-Me bond length of 2.655 24  5  5  2  2  (18) A. The long Y — C interaction that is seen in 7a could be due to the strain of the fused 3-and 4-membered Y-C2-P2 and Y-C2-Si2-Nl rings.  48  2.5  Kinetics of the Thermolysis of M R [ N ( S i M e C H P M e ) 2 ] 2 2  2  2  The yttrium and lutetium hydrocarbyl complexes 4a-6a undergo clean firstorder kinetics, eliminating R—H by abstraction of a PCH Si-methylene hydrogen; 2  this generates the cyclometallated complex shown in Scheme 2.1. The kinetics of this reaction in C6D6 can be conveniently followed by P{ H} NMR spectroscopy by 31  1  measuring the decrease in concentration of Y R [ N ( S i M e C H P M e ) ] , R = Ph, 2  2  2  2  2  CH C6H5, CD C6D5, over time. The first-order rate and Eyring plots are shown in 2  2  Figure 2.13 and the rate data are tabulated in Tables 2.5 and 2.6. From the Eyring plots, the activation parameters are remarkably similar: AH* = 21 kcal/mol and AS* = -3 eu.  The four-centered transition state  25  shown below (Figure 2.12) is a  reasonable one for this process. For such a highly ordered transition state one might expect a large negative AS*.  However, only a small negative value was found. To  account for the rather small, but negative AS*'s observed, a transition state with a dissociated phosphine is proposed as this would be expected to have additional degrees of freedom and be better able to align into the necessary four-centered configuration for hydrocarbon elimination. As phosphine dissociation is rapid for these complexes, such a dissociation should not be the rate-determining step. Me  Si Me  2  - i *  2  Figure 2.12: A possible transition state for the elimination of R—H.  49  Time (seconds)  Eyring data for Y(R){N(SiMe CH PMe2)2}2 2  -11.0  -j  0.0028  1  1  1 0.0029  2  ,  1  0.0030  ,—  0.0031  (K ) 1  temp  Figure  2.13:  The  first-order  rate  plots  for  the  thermolysis  of  Y(CH2C6H5)[N(SiMe2CH2PMe2)2]2,5a, and the Eyring plots for the thermolysis of Y(R)[N(SiMe CH PMe )2]2, R = C H C H , C D C D , Q H 5 . 2  2  2  2  6  5  2  6  5  50  Table 2.5: Rate data for the thermolysis of YR[N(SiMe2CH2PMe2)2] 2  R = C6H Temp  —  R = CH C H  5  2  kobs  Temp  —  47.0  8.25 x IO"  2  —  —  R = CD C6D  5  2  kobs  Temp  43.0  8.03 x IO'  47.0  1.08 x IO-  50.0  1.43 x IO" 2.97 x IO"  56.6  2.43 x IO-  56.5  60.0  3.25 x IO"  —  66.0  5.86 x IO'  73.0  9.91 x IO"  2  6  3  2  kobs  kob (CD2C6D5) S  —  —  —  1.23 x IO"  47.0  2  kobs(CH C6H5)  5  0.88  2  2  —  —  3.36 x IO-  56.5  2  —  0.88  2  2  —  2  —  2  —  —  —  66.5  7.19 x IO-  73.5 75.5  —  66.5  8.49 x IO"  0.85  1.42 x 10-  73.5  1.55 x IO"  2  0.92  1.83 x IO"  75.5  2.02 x 10-  1  0.91  1  1  2  2  Table 2.6: Eyring data for the thermolysis of YR[N(SiMe2CH2PMe2>2]2-  Function  R = Q3H5  correlation  -0.998  -0.999  -0.999  AS* (cal/k/mol)  -4.i ± 3  -3.3 ± 3  -2. ± 3  AH* (Kcal/mol)  20. ±1  20. ±1  20. ±1  5  R = CH2C6H5  R = CD2C6D5  7  6  7  Another interesting feature of this reaction is an apparent inverse isotope effect exhibited by the decomposition of YR[N(SiMe2CH PMe2)2] , R = CH2C6H5 2  and CD C6D5. 2  2  Even though the only C-H bonds being cleaved and formed in the  transition state involve a PCH2Si-methylene hydrogen being transferred to the benzyl  51 ligand to form toluene ( C H 3 C 6 H 5 and C H D 2 C 6 D 5 ) , the formation of C H D 2 C 6 D 5 is faster than the formation of CH3C6H5: kn/ko = 0.85 to 0.92 in the temperature range studied (Table 2.5).  One way to rationalize this observation is to invoke  26  a pre-  equilibrium involving an agostic T| -benzyl ligand going to Tj -benzyl prior to the loss 2  1  of toluene (Equation 2.2).  H L Y ^ C — Ph ^ = ^ r L Y - C H - P h n  n  H  k  2  * >  Products [2.2]  1  T| -Benzyl  r| -Benzyl 2  1  -d[ri -Benzyl] Rate- _  / j^kg _ L i _ ) .Benzyl]  2  Rate = h^A  [lf  h -Benzyl] = (K k )[ii -Benzyl] 2  eq  2  2  [2.3]  [2.4]  For these molecules, the breaking of an agostic benzyl C—H—»Y (or C — D - » Y ) interaction could be required in order for the benzyl ligand to achieve the required geometry for the elimination sequence. interaction then C — D — » M ,  27  As an agostic C—H—»M is a stronger  the pre-equilibrium would generate a higher  concentration of Ti -CD2C6D5 than r^-CF^CsHs resulting in faster elimination of 1  CHD2C6D5  than C H 3 C 6 H 5 .  The measured deuterium isotope effect is therefore  determined by the thermodynamic equilibrium isotope effect of the pre-equilibrium (K q(H)/K q(D) < 1) as the kinetic deuterium isotope effect should be zero. If the e  e  steady-state approximation is assumed (i.e., that the concentration of rj ^benzyl  52  complex remains constant), then the rate is defined as in Equation 2.3. If a further assumption is made that ki »  k then the rate equation simplifies to that in Equation 2  2.4  Unfortunately there is no conclusive evidence for the assumed agostic benzyl ligand. The a-benzyl carbon does display a reduced c-H coupling constant of 115 lT  Hz, a typical agostic spectroscopic feature.  27  However, no evidence for an agostic  C—H—>M was evident in the solid state IR spectra (KBr pellet). It was hoped that the activation parameters for this reaction sequence would provide further evidence for this pre-equilbrium of the agostic benzyl ligand. Unfortunately, because the difference between the rates k b (H) and k bs(D) is so small, the calculated activation 0  D  s  parameters are, within experimental error, indistinguishable (Table 2.6).  It is interesting to compare the rates of cyclometallation for the various M R [ N ( S i M e 2 C H P M e 2 ) 2 J 2 complexes as a function of M and R. At 73 °C, the 2  lutetium-phenyl complex (k b = 1.88 x 10~ sec , half life = 61.3 min) is an order of 4  0  -1  S  magnitude more stable than the corresponding yttrium phenyl complex (k b = 1.65 x 0  S  10" sec* , half life = 7.0 min), which in turn is more stable than the yttrium-benzyl 3  1  complex (kobs = 2.37 x 10" sec , half life = 4.9 min). The difference between the two 3  -1  yttrium complexes is rather small and may reflect the ability of the benzyl ligand to more easily attain the strained four-centered transition state than the phenyl derivative. The difference in rates between Lu and Y is probably due to the smaller size of lutetium relative to yttrium, the smaller metal making it more difficult to achieve the required geometry for the transition state. Consistent with this is the fact that the lanthanum-phenyl complex was not isolable; as the L a the activation barrier is the lowest.  + 3  ion is the largest,  53  2.6  Reactivity of  M[N(SiMe CHPMe )(SiMe CH PMe )][N(SiMe CH PMe ) ] 2  2  2  2  2  2  2  2  2  The strained structure depicted by the X-ray crystal structure determination o f 7a prompted an investigation to see i f this complex might undergo o-bond metathesis reactions.  25  Indeed, i n a sealed N M R tube under approximately four atmospheres o f  D , the M — C bond does react reversibly, presumably generating the undetectable 2  deuteride M D [ N ( S i M e 2 C H D P M e 2 ) ( S i M e C H 2 P M e 2 ) ] [ N ( S i M e 2 C H P M e 2 ) 2 ] . 2  2  This  deuteride can then eliminate H D by a further ligand metallation reaction (Scheme 2.2). However, this reaction only proceeds at high temperatures. N o reaction was detected until the N M R tube had been heated to about 90° C for several hours. A t this point, H D (triplet at 4.42  p p m , ' J H - D = 42.6  H z ) and H2 (at 4.46  ppm) were detectable.  W h e n deuterium N M R spectra were run on these complexes, the spectra showed that deuterium had become incorporated into the silyl methyl (SiCjHj) and the methylene ( S i C H ^ P ) positions i n the amido-diphosphine ligand. Clearly, it must be possible to metallate at either o f these positions f r o m the l i g a n d to the metal, but the thermodynamic product is with metallation at the methylene position. hydride c o m p l e x , H U [ N ( S i M e 3 ) ] 3 , 2  with D . 2  The uranium  has been reported to undergo similar reaction  2 8  Unfortunately, these complexes w i l l only activate their own C-H bonds. When a ds-toluene solution of the yttrium complex was placed under H C for one week, no H D was detectable in the N M R .  2  and heated to 110°  If the ds-toluene were activated  by this complex, then eventually the deuterium label would appear in the H gas. In 2  addition, a deuterium N M R spectrum was obtained which showed no deuterium incorporation i n the complex. The same results were found from sealed samples o f both 7a and 8a in just ds-toluene (no H ) . After extensive heating, 2  2  H N M R spectra  54  showed no uptake of deuterium into the complexes. Also, a dn-cyclopentane solution of the yttrium complex was placed under about four atmospheres of D and heated to 2  95° C for 1 week. Mass spectral analysis of the cyclopentane showed no increase above natural abundance deuterium. Thus, although these cyclometallated compounds are thermally robust (no decomposition of these complexes has been detected even when heated to 110° C for a week) and will engage in a-bond metathesis with H and 2  D they appear to be too sterically crowded to react with larger molecules. 2  Scheme 2.2  M*=M[N(SiMe CH PMe2)2] 2  2  55  2.7  Summary  The synthesis of a variety of new lanthanoid phosphine complexes has been achieved by complexing two amido-diphosphine ligands to yttrium, lutetium or lanthanum. At room temperature these compounds are fluxional and display NMR spectra indicative of complexes where the phosphorus donors are rapidly exchanging, probably via a dissociation-reassociation pathway. The small lutetium and yttrium complexes are monomelic and appear to be coordinatively saturated. However, the lanthanum complexes may be dimeric at lower temperatures indicating that the larger La  + 3  centre may be capable of attaining eight coordination. It is possible to generate  thermally unstable hydrocarbyl complexes of the type M(R)[N(SiMe2CH2PMe2)2]2 which undergo a clean first order elimination of R-H to generate cyclometallated l  1  complexes of the type M[N(SiMe CHPR )(SiMe2CH PR2)][N(SiMe2CH PR2)2]2  2  2  2  These thermally robust compounds will undergo a-bond metathesis with H2 and D2 at high temperature, but appear to be too sterically congested to react with larger molecules.  Therefore, it would appear that these compounds are less reactive than  other seven-coordinate lanthanoid complexes of the type Cp2Ln(R).  2.8  2.8.1  Experimental Procedures  General Information. All manipulations were performed under prepurified  nitrogen in a Vacuum Atmospheres HE-553-2 glovebox equipped with a MO-40-2H purification system or in standard Schlenk-type glassware on a dual vacuum/nitrogen line. Molecular weight determinations were carried out in C6Dg using the isopiestic method in a Signer molecular weight apparatus. 29  prepared from the oxides  30  31  Anhydrous LaCl3 and YCI3 were  (Aldrich), while anhydrous LUCI3 was used as received  (Aldrich). HN(SiMe2CH2Cl)2 (Aldrich or Silar) was distilled prior to use and stored  56  under vacuum. Phenyllithium, benzylpotassium ( K C D 2 C 6 D 5 was prepared using 32  C D CD ), 6  5  LiCH SiMe  3 3  3  2  3 4 3  ,  HPMe ,  3 5  2  HP(CHMe ) ,  HP(CMe ) ,  3 7  LiN(SiMe CH PPh ) ,  38  2  3  2  LiN(SiMe CH PMe ) ,  1 1  HN(SiMe CH PPh ) ,  were prepared according to the literature procedures. The  2  2  2  2  2  2  LiN(SiMe CH PPr ) ,  3 6  2  i  2  37  2  2  2  2  11  2  2  2  2  2  syntheses of K N ( S i M e C H P M e ) and KN(SiMe CH PPh ) are given in section 2  2  2  2  2  2  2  2  3.6. Hexanes and THF were initially dried over CaH followed by distillation from 2  sodium-benzophenone ketyl. benzophenone ketyl.  Ether and toluene were distilled from sodium-  The deuterated solvents C6D6 and CgD5CD were dried 3  overnight with activated 4A molecular sieves, vacuum transferred to an appropriate container, "freeze-pump-thawed" three times and stored in the glovebox.  Carbon,  hydrogen and nitrogen analyses were performed by P. Borda of this department. NMR spectra were recorded in C6D6 unless otherwise stated. H NMR spectra (referenced L  to CgD H at 7.15 ppm or C6DsCD H at 2.09 ppm) were performed on one of the 5  2  following instruments depending on the complexity of the particular spectrum: Bruker WP-80, Varian XL-300, Bruker WH-400 or a Bruker AM-500.  1 3  C NMR spectra  (referenced to C D at 128.0 ppm or C 6 D s £ D at 20.4 ppm) were run at 75.429 MHz 6  6  3  coupling constants are reported in square brackets) and  OJQ-U  3 1  P NMR spectra  (referenced to external P(OMe) in CgDg or C6D5CD at 141.0 ppm) were run at 3  121.421 MHz, both on the XL-300.  3  8 9  Y NMR spectra (referenced to external 3M  YC1 in D 0 at 0 ppm) were run at 19.6 MHz (Bruker WH-400) and 24.9 MHz 3  2  (Bruker AM-500). All chemical shifts are reported in ppm and all coupling constants are reported in Hz.  2.8.2  YCl[N(SiMe CH PMe )2]2, la. To a slurry of YC1 (1.381 g, 7.07 mmol) 2  2  2  3  in THF (100 mL) was added a solution of L i N ( S i M e C H P M e ) (4.08 g, 14.20 2  2  2  2  mmol) in THF (10 mL) dropwise with good stirring. After 12 hours the THF was removed under vacuum, hexanes (50 mL) were added and the solution was filtered  57 through Celite® to remove LiCl. Cooling a saturated hexanes solution to -30 °C gave analytically pure crystals o f YCl[N(SiMe2CH2PMe2)2k (3.60 g, yield 74%). *H  NMR: 8 1.06 (24H, s, P M e ) , 0.81 (8H, s, PCH Si) and 0.35 (24H, s, SiMe).  1 3  2  C  NMR: 8 20.03 (s, PCH Si), 15.89 (s, PMe) and 7.27 (s, SiMe). 31p{lH} NMR: 8 2  -45.7 (d, J = 52) (See Table 2.1 & Figure 2.10). Anal. Calcd. for C o H C l N 2 P 4 S i 4 Y : 56  2  C, 35.05; H, 8.24; N, 4.09. Found: C, 35.05; H, 8.30; N, 4.02. Signer molecular weight method, calculated monomeric molecular weight: 685 g/mol. Found: 635 g/mol.  The same  YCl[N(SiMe CH PPh )2]2» lb.  2.8.3  2  2  2  procedure  as f o r  YCl[N(SiMe2CH2PMe2)2l2 was used except that the product was extracted with toluene and c r y s t a l l i z e d f r o m toluene/hexanes. LiN(SiMe CH PPh )2 2  (0.89  2  2  mmol)  g, 1.66  YCI3 (0.16 g, 0.83 mmol) and gave 0.78  g (80% yield) of  YCl[N(SiMe CH PPh )2]2. *H NMR: 8 7.67 (16H, m, HQ), 7.14 (24H, m, H & 2  2  2  m  Hp), 1.80 (8H, s, PCH Si) and 0.33 (24H, s, SiMe). " C NMR: 8 138.68 (br, Q ) , 2  133.53 (d, J = 14.1, C ), 128.53 (d, J = 3.3, C ), 129.10 (s, Cp), 17.43 (m, PCH Si) 0  m  2  and 5.91 (s, SiMe). 31p{lH} NMR in C D C D : at 29° C, 8 -16.3 (d, J = 39); at 6  5  3  59° C, -9.2 (m), -18.8 (m), -19.8 (m) , -20.6 (s) (See Figure 2.6).  A n a l . Calcd. for  C oH 2ClN2P Si4Y : C, 60.98; H, 6.14; N , 2.37. Found: C, 61.02; H, 6.33; N , 2.40. 6  4  7  YCl[N(SiMe CH PPr )2]2, lc.  2.8.4  2  2  i  2  Y C l [ N ( S i M e C H P M e 2 ) 2 ] 2 was used. 2  2  The same YC1 (0.28 3  procedure  g,  1.41  as f o r  mmol) and  LiN(SiMe CH PPr )2 "(1.13 g, 2.82 mmol) gave YCl[N(SiMe CH PPr 2)2]2. i  2  2  i  2  2  2  Because o f the high solubility of the compound (1 gram w i l l dissolve i n less than 1 m L of pentane) analytically pure material has not yet been obtained. *H NMR: 8 1.87  (8H, sept, J = 7.0, PCH), 1.16 (48H, m, PCMe), 0.91 (8H, s, PCH Si) and 0.50 (24H, 2  s, SiMe). 13c NMR: 8 24.47 (s, PCHMe ), 19.68 (t-4.0 Hz, P C H M e o ) . 11.23 (t-5 2  Hz, PCH Si) and 6.00 (s, SiMe). 31p{lH} NMR: 8 -1.09 (d, J = 44). 2  58  2.8.5  LuCl[N(SiMe2CH2PMe2>2]2> 2a.  The same procedure as f o r  Y C l [ N ( S i M e 2 C H P M e 2 ) 2 l 2 was used. LuCl (0.50 g, 1.79 mmol) was reacted with 2  3  LiN(SiMe2CH PMe2) 2  2  (1.03 g , 3.58 mmol) to give 0.86 g (63% yield) o f  LuCl[N(SiMe CH PMe2)2]2- N M R spectra are recorded i n C6D CD . l H NMR: 8 2  2  5  3  1.06 (24H, s, PMe), 0.80 (8H, s, PCH Si) and 0.34 (24H, s, SiMe). 13c{lH} NMR: 2  [ Jc-H] 5 20.48 (s, PCH Si) [t, 120.8], 16.13 (s, P M e ) [q, 128.3], and 7.11 (s, SiMe) !  2  [q, 117.3]. 31p{lH} NMR: at 20 °C 8 -42.93 (s); at -80 °C 8 -40.8 (br, s) and -42.8 (br, s). Anal. Calcd. for C 2 o H C l N 2 P 4 S i 4 L u : 56  C, 31.14; H , 7.32; N , 3.63. Found: C,  31.34; H,7.42; N, 3.50.  2.8.6  LaCl[N(SiMe2CH2PMe2)2l2»  3a.  The same procedure as f o r  Y C l [ N ( S i M e 2 C H 2 P M e 2 ) 2 ] 2 was used except that one week o f stirring at room temperature was required. LaCl (0.38 g, 1.57 mmol) and K N ( S i M e 2 C H 2 P M e 2 ) 2 3  (1.00 g, 3.13 mmol) gave 0.85 g (74% yield) o f LaCl[N(SiMe CH PMe2)2]2- N M R 2  spectra are recorded i n C D C D . 6  5  3  2  *H NMR: 8 1.09 (24H, s, P M e ) , 0.79 (8H, s,  P C H S i ) and 0.27 (24H, s, SiMe). 13c{lH} NMR: [1J -H] 5 20.05 (s, PCH Si) [t, C  2  2  118.4], 16.05 (s, P M e ) [q, 127.7], and 6.81 (s, SiMe) [q, 117.1]. 3 1 p { l H } NMR: at 20 °C 8 -43.51 (s); at -60 °C 8 -40.42 (br, s) and -42.47 (br, s). Anal. Calcd. f o r C oH56ClN P4Si La: C, 32.67; H , 7.68; N , 3.81. Found: C, 32.67; H , 7.82; N , 3.70. 2  2  4  Signer molecular weight method, calculated monomelic m o l . wt.: 735 g/mol. Found: 685 g/mol.  2.8.7  LaCI[N(SiMe2CH PPh2)2]2, 3b. 2  T h e same  procedure  as  for  Y C l [ N ( S i M e 2 C H 2 P P h 2 ) 2 ] 2 was used except that one week o f stirring at r o o m temperature was required. LaCl (0.25 g, 1.01 mmol) and KN(SiMe2CH2PPh2)2 (1.15 3  g, 2.02 mmol) gave 0.80 g (64% yield) o f LaCl[N(SiMe CH PPh2)2]2- N M R spectra 2  2  59 are reported in C6D5CD3. *H NMR:  at 80 °C, 8 7.50 (16H, s,  HQ),  Hp), 1.69 (8H, s, PCH Si), 0.05 (24H, s, SiMe). *3c{lH} NMR:  6.99 (24H, s, H  M  ,  at 60 °C, 8 139.05  2  (br, Q), 133.71 (m, C ), 128.58 (s, C ), 129.06 (s, C ), 17.59 (m, PCH Si) and 5.62 0  m  p  2  at 80 °C, 8 -12.3 (monomer), at -39 °C 8 -11.2 (s) and -  (s, SiMe). 31p{lH} NMR:  19.6 (s) (dimer). In between this temperature range both species are detectable (See Figure 2.7). This compound crystallizes in a 2:1 ratio with associated toluene: Anal. Calcd. for C6 H7 ClN P Si4Y(0.5 C H ): C, 59.68; H, 5.99; N, 2.19. Found: C, 60.01; 0  2  2  4  7  8  H, 6.00; N, 2.15. Signer molecular weight method, calculated monomelic molecular weight: 1232 g/mol. Found: 1337 g/mol.  Y(C H5)[N(SiMe2CH PMe2)2]2, 4a. To an ether solution (25 mL) of  2.8.8  2  6  YCl[N(SiMe CH PMe ) ] (0.630 g, 0.919 mmol) was added an ether solution (5 2  2  2  2  2  mL) of PhLi (0.077 g, 0.916 mmol). After 20 minutes the ether was removed under vacuum, the resulting oil extracted with toluene and the solution was filtered through Celite® to remove LiCl. Addition of hexanes (1 mL) to a saturated toluene solution and  cooling to -30 °C gave 0.382 g (57% yield) of colorless crystalline at 20 °C 8 8.37 (2H, d, J = 6.9, HQ), 7.37  YPh[N(SiMe CH PMe ) ] . *H NMR: 2  2  2  2  2  (2H, t, J = 6.8, H ), 7.22 (IH, t, J = 6.9, H ) 0.90 (24H, s, PMe), 0.73 (8H, s, PCH Si) m  p  2  and 0.41 (24H, s, SiMe); at -49 °C in C 6 D 5 C D 3 8 8.45 (H ), 7.43 (H ), 7.25 (H ) 0  m  p  0.98, 0.95, 0.78 & 0.72 (PMe), 1.41, 0.81, 0.39 & -0.01 (PCH Si) and 0.64, 0.61, 0.45 2  8 191.0 (d, J = 41.5, Q), 142.3 (s, C ), 125.7 (s, C ) ,  &0.18 (SiMe). 13C NMR:  0  m  124.9 (s, C ), 20.36 (s, PCH2Si), 16.64 (s, PMe) and 7.35 (s, SiMe); at -49° C in p  C D CD 6  5  3  8 142.70 (s, C ), 125.52 (s, C ) , 124.72 (s, C ), 19.64 & 19.40 (s, 0  m  p  PCH2Si), 17.32, 16.11, 15.78 & 15.77 (s, PMe) and 8.20, 7.42, 7.21 & 6.33 (s, SiMe). 3lp{lH} NMR: at 20 °C 8 -46.7 (d, J = 43); at -49 °C 8 -43.6 (m) & -48.8 (m) (See Table 2.1 & Figures 2.1, 2.2 and 2.3). Anal. Calcd. for C H iN P Si4Y: C, 26  42.96; H, 8.46; N, 3.85. Found: C, 43.20; H, 8.55; N, 3.81.  6  2  4  60  Y(CH C6H5)[N(SiMe2CH PMe2)2]2» 5a. The same procedure was  2.8.9  2  2  followed as for the above compound except that THF was the solvent used. YCl[N(SiMe CH PMe ) ] (0.500 g, 0.730 mmol) and C H CH K(0.095 g, 0.730 2  mmol)  2  2  gave  2  2  6  0.413  g  (76%  yield)  of  5  2  colorless  crystalline  Y(CH C H )[N(SiMe CH PMe ) ] . *H NMR: 5 7.22 (2H, t, J = 7.5, H ), 7.12 2  6  5  2  2  2  2  2  m  (2H, d, J = 6.9, Ho), 6.81 (IH, t, J = 7.2, H ), 2.06 (2H, br, Y-CH ) 0.97 (24H, s, p  2  PMe), 0.74 (8H, s, PCH Si) and 0.35 (24H, s, SiMe).  NMR: [UC-H] 8 155.3 (s,  2  Q), 128.2 (s, C ) [d, 154.3], 125.1 (s, C ) [d, 152.4], 117.4 (s, C ) [d,158.3], 55.85 (d 0  m  p  of q-30.4 & 4.1 Hz, Y-CH ) [t,114.9], 20.16 (s, PCH2Si) [t,118.5], 16.64 (s, PMe) 2  [q,128.2] and 7.35 (s, SiMe) [q,117.2]. 31P{lH} NMR: 8 -46.7 (d, J = 43). Anal. Calcd. for C H 3N P Si4Y: C, 43.77; H, 8.57; N, 3.78. Found: C, 43.56; H, 8.70; N, 27  6  2  4  3.60. Y(CD C6D5)[N(SiMe CH PMe ) ] was synthesized in the identical manner 2  2  2  2  2  2  using KCD C6D5 as the alkylating agent. This compound shows identical P{ H} 31  1  2  and *H NMR spectra to 5a except that no *H resonances are observed for the benzyl ligand.  2.8.10  Lu(C H )[N(SiMe CH2PMe2)2]2»6a. 6  The same procedure as for  2  5  YPh[N(SiMe CH PMe ) ] was used. LuCl[N(SiMe CH PMe ) ] (0.205 g, 0.266 2  2  2  2  2  2  2  2  2  2  mmol) and C H L i (0.023 g, 0.27 mmol) gave 0.19 g (87% yield) of colorless 6  5  crystalline LuPh[N(SiMe CH PMe ) ] . 2  2  2  2  2  !H NMR: at 20 °C 8 8.24 (2H, d, J = 6.6,  NMR spectra are reported in C6D5CD3. HQ), 7.28  (2H, t, J = 7.2, H ), 7.11 (IH, t, J m  = 7.2, Hp), 0.94 (24H, s, PMe), 0.68 (8H, s, PCH Si) and 0.37 (24H, s, SiMe); at -70 2  °C 8 8.52 (H ), 7.50 (H ), 7.28 (H ), 0.98, 0.95, 0.76 & 0.76 (PMe), 1.39, 0.80, 0.39 & 0  m  p  -0.73 (PCH Si) and 0.71, 0.65, 0.49 & 0.20 (SiMe). 13c{lH} NMR: at 20 °C 8 195 2  (s, Q), 142.77 (s, C ), 125.96 (s, C ), 124.98 (s, C ), 20.10 (s, PCH Si), 16.99 (s, 0  m  p  2  PMe) and 7.35 (s, SiMe); at -49 °C 8 195.5 (Q), 143.83 (C ), 125.73 (C ), 124.73 0  m  61  (C ), 20.05 &19.56 (PCH Si), 17.68, 16.61, 16.34 & 16.21 (PMe) and 8.20, 7.78, 7.16 p  2  & 6.68 (SiMe).  31P{lH} NMR:  at 20 °C 8 -43.58 (s); at -59 °C 8 -39.69 (m) and  -46.40 (m) (See Table 2.1 & Figure 2.4). Anal. Calcd. for C o H C l N P S i 4 Y : C, 2  5 6  4  2  35.05; H, 8.24; N, 4.09. Found: C, 35.05; H, 8.30; N, 4.02.  2.8.11 Y [ N ( S i M e C H P M e ) ( S i M e C H P M e ) ] [ N ( S i M e C H P M e ) ] , 7 a . 2  2  2  2  2  2  2  2  2  Thermolysis of YBz[N(SiMe CH PMe2)2]2 or Y P h [ N ( S i M e C H P M e ) ] in 2  2  2  2  2  2  toluene results in quantitative conversion to this cyclometallated product.  2  This  compound is exceedingly soluble in pentane and has only been isolated in very low yield.  NMR spectra are recorded in C 6 D 5 C D 3 . * H N M R : at -38 °C sharp  resonances between 8 1.35 and 0.92 (PMe and YCHP), multiplets between 8 0.85 and 0.40 (PCH Si, some are obscured), and 0.49, 0.38, 0.37, 0.34, 0.33, 0.29, 0.23, & 0.22 2  (8-SiMe).  13  C { H } N M R : at -28 °C. 8 32.29 (d of d, J = 44.7 & 9.3, YCHP), 22.17, 1  21.41, & 20.3 (3-PCH Si), 18.82, 18.50, 18.40, 17.43, 16.16, 15.77, 15.53, &14.80 (82  PMe), and 10.03, 8.29, 7.59, 7.35, 7.14, 6.99, 6.76, & 5.63 (8 SiMe).  31  P{!H} NMR:  at -29 °C 8 -34.2 (m), -41.9 (m), -42.0 (m), & -45.3 (m) (See Table 2.2 and Figure 2.8) Anal. Calcd. for C20H55N2P4SUY: C, 37.02; H, 8.54; N, 4.32. Found: C, 37.41; H, 8.54; N, 4.22.  2.8.12 Y [ N ( S i M e C H P P h ) ( S i M e C H P P h ) ] [ N ( S i M e C H P P h ) ] , 7 b . 2  2  2  2  2  2  2  2  2  To a toluene solution (50 mL) of YCl[N(SiMe2CH PPh )2]2 (0.615 g, 0.836 2  2  mmol) was added a toluene solution (10 mL) of LiCH SiMe3 (79 mg, 0.84 mmol) 2  dropwise, with good stirring. The mixture immediately became cloudy due to the formation of LiCl.  After stirring for two hours, the solution was filtered through  Celite® and the filtrate was evaporated to dryness to remove SiMe4. The crude crystalline product was redissolved in a few mL of toluene and cooled to -30 °C to give 0.395 g of product (68% yield) *H NMR: 8 8.1 to 6.8 (broad signals for phenyl resonances), 2.0 to -1.0 (broad signals for SiMe and PCHSi resonances).  31  P{ H.} 1  62 3 1 p { l H } N M R : 8 - 0.25 (m, P2),  (broad signals for SiMe and PCHSi resonances). -9.07 (m, PI) ~ -11( very broad P3 & P4).  (See Table 2.2 for analysis of low  temperature 31p{lH} NMR data). Anal. Calcd. for C 6 o H i N P 4 S i 4 Y : C , 62.92; H, 2  7  6.25; N, 2.45. Found: C, 63.34; H, 6.45; N, 2.35.  2.8.13  Lu[N(SiMe CHPMe )(SiMe CH PMe )][N(SiMe CH PMe ) ], 2  2  2  2  2  2  2  2  2  8a.  This compound can be quantitatively formed from the phenyl-lutetium compound as with yttrium. It too has only been isolated in small yield due to its extreme solubility in pentane. * H N M R of this compound consists of sharp resonances between 8 1.35 and 0.93 (PMe and LuCHP), multiplets between 8 0.82 and 0.40 (PCH Si), and 0.41, 2  0.33, 0.31, 0.29, 0.27, 0.24, 0.21, & 0.20 (8-SiMe). 3 C { H } N M R : in C D C D at 1  1  6  5  3  28 C. 8 34.03 (d of t, J = 43.6 & 4, LuCHP), 30.19, 22.77, & 20.0 (3-PCH Si), 2  resonances from 21 to 15, (8-PMe), and 10.36, 7.83, 7.72, 7.43, 7.17, 6.78, 6.55, & 5.69 (8 SiMe).  3 l p l } N M R : 8 -34.8 (m), -36.1 (m), -38.6 (m), & -40.1 (m) {  H  (See Table 2.2 and Figure 2.9). Anal. Calcd. for C o H N P S i 4 L u : C, 32.69; H, 7.54; 2  5 5  4  2  N,3.81. Found: C, 33.20; H, 7.57; N, 3.42.  2.8.14  La[N(SiMe CHPMe )(SiMe CH PMe )][N(SiMe CH PMe ) ], 9a. 2  2  2  2  2  2  2  2  2  To a hexanes solution (50 mL) of LaCl[N(SiMe CH PMe ) ] (0.615 g, 0.836 mmol) 2  2  2  2  2  was added a hexanes solution (10 mL) of L i C H S i M e 3 (79 mg, 0.84 mmol) dropwise, 2  with good stirring. The mixture immediately became both cloudy (due to the formation of LiCl) and bright yellow (due to metallation of the ligand) in appearance. After stirring for 2 hrs., the solution was filtered through Celite® and the filtrate was evaporated to dryness to remove S i M e 4 .  The  crude crystalline product was  redissolved in a few mL of hexanes and cooled to -30 °C to give 0.395 g of product (68% yield). NMR spectra are reported in CD3C6D5. * H NMR at 20 °C: 8 1.30 (d, J = 6, PMe ), 1.24 (m, PCH(Y)(Si)), 1.03 (s, 2 PMe ), 1.01 (d, J = 4, PMe ), 0.90 (m, 2  2  2  63 PCH Si), 0.68 (m, 2 PCH Si), 0.28 (s, SiMe ), 0.17 (s, SiMe ), 0.14 (s, 2 SiMe ). 2  2  2  2  2  3lP{lH} N M R at -99 °C 5 -21.3 (d, J = 27), -35.5 (broad), -37.3 (very broad), & 38.3 (d, J = 27). Anal. Calcd. for C oH 5N P Si4La: C, 34.33; H, 7.92; N, 4.00. Found; 2  5  2  4  C, 34.05; H, 7.94; N, 4.00.  2.8.15 of  K i n e t i c s o f the T h e r m o l y s i s Reactions.  The first order decomposition  M(R)[N(SiMe CH PMe ) ] complexes was monitored using P{!H} NMR 31  2  2  2  2  2  spectroscopy by following the disappearance of the hydrocarbyl complex over time. In order to insure accurate integrations a twelve second delay between 20° pulses was utilized. Typically, the spectra were collected at room temperature on sealed 0.09 mol/L C(,D^ solutions in sealed NMR tubes. These samples were immersed in an oil bath (maintained at a specific temperature) for a known length of time and the reaction was quenched by freezing the sample. For the do- and d7-benzyl compounds the samples were treated identically; each sample spent exactly the same length of time in the oil bath, frozen, and in the spectrometer. The observed rate constants were determined from the slope of the graph: ln{([A]o / [A]o-x)} versus time by plotting the ln(l / % starting material) versus time (least squares fit). The AH* and AS* were determined from the Eyring plots: ln(k b / temp) versus 1 / temp (least squares fit). 0  s  AH* = -R(slope) and AS* = R[intercept - ln(k / h)] where R = gas constant, h = B  Planck's constant and k = Boltzmann constant. B  2.8.16  Calculation of AG* from Fluxional N M R  calculated using the value for the rate constant  39  equation AG* = -RT ln[(k h) / (k T )]. c  c  B  c  Behaviour.  The AG* were  1^(1^ = 7 t A u / 2 / ) in the Eyring 1  2  c  R = gas constant, T = temperature of c  coalescence, A u = peak separation in the low temperature limit, h = Planck's constant c  and k = Boltzmann constant. B  64  2.9 References 1  a) Marks, T. J.; Ernst, R. D. In Comprehensive Organometallic Chemistry; Wilkinson, G.; Stone, F. G. A.; Abel, E. W., (eds.); Pergamon: Oxford, 1982, Chapter 21 and references therein, b) Schumann, H. Angew. Chem., Int. Ed. Engl. 1984,23, 474 and references therein.  2  Wilkinson, G.; Birmingham, J. M. J. Am. Chem. Soc. 1956, 78, 42.  3  Watson, P. L. J. Am. Chem. Soc. 1982,104, 337.  4  Watson, P. L.; Parshall, G. W. Acc. Chem. Res. 1985, 75, 51.  5  Evans, W. J.; Meadows, J. H.; Wayda, A. L.; Hunter, W. E.; Atwood, J. L. / . Am. Chem. Soc. 1982,104, 2009.  6  a) Evans, W. J.; Meadows, J. H.; Wayda, A. L.; Hunter, W. E.; Atwood, J. L. / . Am. Chem. Soc. 1982,104, 2015. b) Evans, W. J.; Bloom, I.; Hunter, W. E.; Atwood, J. L. J. Am. Chem. Soc. 1983,105, 1401. c) Evans, W. J.; Meadows, J. H.; Hunter, W. E.; Atwood, J. L. Organometallics, 1983,2, 1252. d) Evans, W. J.; Meadows, J. H.; Hunter, W. E.; Atwood, J. L. J. Am. Chem. Soc. 1984,106, 1291. e) Evans, W. J.; Meadows, J. H.; Hanusa, T.P. / . Am. Chem. Soc. 1984, 106, 4454.  7  Thompson, M. E.; Baxter, S. M.; Bulls, A. R.; Burger, B. J.; Nolan, M. C ; Santarsiero, B. D.; Schaefer, W. P.; Bercaw, J. E. / . Am. Chem. Soc. 1987, 709, 203.  8  O'Hare, D.; Manriquez, J.; Miller, J. S. / . Chem. Soc, Chem. Comun. 1988, 491.  9  Shannon, R. D. Acta Cryst. 1976, A32, 751. Drew, M. G. B. Prog. Inorg. Chem. 1977,23, 67.  65  Fryzuk, M.  D.; Carter, A.; Westerhaus, A. Inorg. Chem.  1985,24,  642.  Fryzuk, M. D.; Haddad, T. S.; Rettig, S. J . Organometallics, 1 9 8 9 , 5, 1723. a) Kronenbitter, J.; Schwenk, A. Z. Phys. A, 1 9 7 7 , 2 5 0 , 117. b) Kronenbitter, J.; Schwenk, A. / . Mag. Res. V.;  1977,25,  147. c) Adam, R. M.;  Fazakerley, G.  Reid, D. G.J. Mag. Res. 1 9 7 9 , 33, 655. d) Levy, G. C ; Rinaldi, P. L.;  1 9 8 0 , 4 0 , 167. e) Chim. Acta, 1 9 8 6 , 1 1 3 ,  Bailey, J. T. / . Mag. Res.  Holloway, C. E.; Mastracci, A.;  Walker, I. M. Inorg.  187.  Evans, W. J.; Meadows, J. H.; Kostka, A. G.; Closs, G. L. Organometallics,  1 9 8 5 , 4 , 324.  Reger, D.L.;  Lindeman, Lebioda, L. Inorg. Chem.  1988,27,  1890.  Hitchcock, P. B.; Lappert, M. F.; MacKinnon, I. A. / . Chem. Soc, Chem. Commun. 1 9 8 8 , 1557. Stults, S.; Zalkin, A. Acta Cryst. 1 9 8 7 , C43, 430. Brennan, J. G.; Stults, S. D.; Andersen, R. A.; Zalkin, A. Organometallics,  1 9 8 8 , 7, 1329. Tilley, T. D.; Andersen, R. A.; Zalkin, R. A., Inorg. Chem. 1 9 8 3 , 22, 856. Tilley, T. D.; Andersen, R. A.; Zalkin, R. A., / . Am. Chem. Soc.  1982,104,  3725. Booij, M.;  Kiers, N. H.;  Meetsma, A.; Teuben, J. H.;  Smeets, W. J. J.; Spek, A.  L. Organometallics, 1 9 8 9 , 5, 2454. Haan, K. H. den; Boer, J. L. de; Teuben, J. H.; Spek, A. L.; Hays, G. R.; Huis, R. Organometallics,  Kojic-Prodic, B.;  1 9 8 6 , 5 , 2389.  66  2 3  Evans, W. J.; Drummond, D. K.; Hanusa, T. P.; Doedens, R. J. Organometallics, 1987, 6, 2279.  2 4  Holton, J.; Lappert, M. F.; Ballard, D. G. H; Pearce, R.; Atwood, J. L.; Hunter, W. E. / . Chem. Soc, Dalton Trans. 1979, 54.  2 5  Thompson, M . E.; Baxter, S. M.; Bulls, A. R.; Burger, B. J.; Nolan, M . C.; Santarsiero, B. D.; Schaefer, W. P.; Bercaw, J. E. J. Am. Chem. Soc. 1989,109, 203.  2 6  Parkin, G.; Bercaw, J. E. Organometallics, 1989,5, 1172.  2 7  Brookhart, M.; Green, M. L. H. J. Organomet. Chem. 1983,250, 395.  2 8  Simpson, S. J.; Turner, H. W.; Andersen, R. A. / . Am. Chem. Soc. 1979,101, 7728.  2 9  Gordon, A. J.; Ford, R. A. The Chemist Companion, John Wiley & Sons: Toronto, 1972, 454.  3 0  a) Signer, R. Liebigs Ann. Chem. 1930,475, 246. b) An apparatus, nearly identical to the one used in our laboratory, has recently been described: Zoellner, R. W. / . Chem. Ed. 1990, 67, 714.  3 1  Taylor, M. D.; Carter, C. P. / . Inorg. Nucl. Chem. 1962,24, 387.  3 2  Schlosser, M.; Ladenberger, V. / . Organomet. Chem. 1967,5, 193.  3 3  Schlosser, M.; Hartmann, J. Angew. Chem., Int. Ed. Engl. 1973,12, 508.  3 4  Schrock, R. R.; Fellmann, J. D. / . Am. Chem. Soc. 1978,100, 3359.  3 5  Parshall, G. W. Inorg Synth. 1968,11, 157.  3 6  Issleib, K.; Krech, F. J. Organomet. Chem. 1968,13, 283.  67  3 7  Hoffmann, H.; Schellenbeck, P. Chem. Ber. 1966, 99, 1134.  3 8  Fryzuk, M . D.; MacNeil, P. A.; Rettig, S. J.; Secco, A. S.; Trotter, J. Organometallics, 1982, i , 918.  3 9  Thomas, W. A. Annu. Rev. NMR Spectrosc. 1968,1, 43.  68  CHAPTER 3:  MONO(AMIDO-DIPHOSPHINE) COMPLEXES OF YTTRIUM AND LUTETIUM  3.1 Introduction  This chapter describes the syntheses and some preliminary reactivity studies of mono(amido-diphosphine) complexes of yttrium and lutetium, the second class of lanthanoid phosphine target molecules. As the bis(amido-diphosphine) complexes of yttrium and lutetium achieved steric saturation by being seven-coordinate, it seemed reasonable that mono(amido-diphosphine) complexes would generate more reactive and perhaps more complex compounds. The mononuclear mono(ligand) complex, MCl2[N(SiMe2CH2PR2)2l> is ° t yfive-coordinate;in order for the metal to achieve n  steric saturation, coordination of a base such as THF or else dimerization of the complex would have to occur. As bulky phosphine donors can make oligomerization difficult (due to inter-ligand steric repulsions) the variation in the size of the phosphorus donor could also be important and perhaps enable the isolation of coordinatively unsaturated complexes.  The major problem encountered with the  bis(amido-diphosphine) complexes, MR[N(SiMe2CH2PMe2)2l2» is the tendency to eliminate R — H and form a not very reactive cyclometallated compound. It was anticipated that hydrocarbyl-containing mono(amido-diphosphine) derivatives might be more stable than the bis(amido-diphosphine) counterparts, and as a result, would exhibit more varied reactivity patterns.  As these mono(amido-diphosphine) complexes can be considered analogous to mono(cyclopentadienyl) lanthanoid complexes, a short summary of some of this work is presented here. Lanthanoid derivatives containing only one cyclopentadienyltype ligand, first synthesized  1  in 1963, have only recently been structurally  69 characterized; s o l i d state. 2  both CpErCl2(THF)3 and Cp*Cel2(THF)3 are eight-coordinate i n the 3  C o m p l e x e s containing L i C l , Cp*LnCl3Li(THF)2  ( L n = L a , Ce;  structures unknown), are also obtained for the early lanthanoid c h l o r i d e s .  4  A six-  coordinate dimer, [Cp*Ce(OCMe3)2l2. containing two bridging and two terminal alkoxide ligands has also been structurally characterized, while Cp*Ce(0-2,65  C 6 H 3 B u ) 2 is monomelic in the solid state, achieving six-coordination v i a interaction t  2  of one o f the t-butyl methyl groups with the metal centre. hydrocarbyl-containing derivatives are quite rare.  Mono(cyclopentadienyl)  6  The first such complexes were  obtained with coordinated l i t h i u m ; [Li(TMEDA)2]Cp*LuMe3 Cp*Lu(Bu )2Cl have both been structurally characterized. l  7  and [ L i ( T H F ) 3 J -  The first such salt-and-  solvent free complexes, Cp*Y(o-C6H4CH2NMe2)2 and Cp*La[CH(SiMe3)2]2» were both reported i n 1989 . 4  Both C p * L a [ C H ( S i M e 3 ) ] 2  8  2  and its T H F adduct,  C p * L a [ C H ( S i M e 3 ) 2 ] 2 ( T H F ) have been crystallographically characterized.  Each  complex displays agostic P-silyl-methyl bonds with the T H F adduct having the weaker interaction.  3.2  8  Syntheses of M C l 2 [ N ( S i M e C H P M e 2 ) 2 ] 2  2  The first attempts to generate mono(amido-diphosphine) complexes were made by reacting YCI3 with one equivalent o f L i [ N ( S i M e 2 C H 2 P M e 2 ) 2 ] i n either toluene or T H F (Equations 3.1 and 3.2).  YCI3 + L i [ N ( S i M e C H P M e ) ] 2  2  2  toluene  2  24 hr  •  no reaction  [3.1]  THF Y C I 3 + Li[N(SiMe CH PMe ) ] 2  2  2  •  2  24 hr  YCl [N(SiMe CH PMe ) ] + LiCl[3.2] 2  2  2  2  2  70  No reaction occurred in toluene, presumably due to the insolubility of YCI3. However, in THF both solids dissolved to give a clear colourless solution. The P{ H} NMR 31  1  spectrum of this crude mixture (in CeDe/THF) clearly showed phosphine coordination to yttrium (a doublet at -42 ppm with ! J Y - P = 77 Hz). However, the product obtained from this reaction by removal of the THF was insoluble in either toluene or ether, so separation from LiCl was not possible.  To overcome this problem it was decided to synthesize a new ligand salt, one that contained potassium instead of lithium, K[N(SiMe2CH2PMe2)2l- The byproduct of reaction 3.2 would then be KCI which is insoluble in THF, thus facilitating the isolation of YCl [N(SiMe2CH PMe2)2]2  2  The synthesis of K[N(SiMe CH PMe2)2] 2  2  should be possible by reacting HN(SiMe2CH2Cl)2 with KPMe2 (Equation 3.3), in analogy to the formation of Li[N(SiMe2CH PMe2)2] from HN(SiMe2CH Cl)2 and 9  2  2  LiPMe2THF 3KPMe + HN(SiMe CH Cl) 2  2  2  •  2  K[N(SiMe CH PMe ) ] + HPMe [3.3] 2  2  2  2  2  -2 KCI  In order to obtain the required KPMe , HPMe2 was deprotonated with 2  benzylpotassium, by vacuum transferring an excess of HPMe2 onto a cold (-78 °C) THF solution of KCH2C6H5 and allowing the mixture to warm slowly to room temperature (Equation 3.4). THF K C H C H + HPMe 2  6  5  •  2  -78 °C  KPMe + C H C H 2  3  6  5  [3.4]  71  Removal of the volatiles (toluene, THF, HPMe2), washing the solid with hexanes and drying under vacuum left a freely-running, off-white powder for a 96% yield of KPMe2, based on KCH2C6H5 used. It is crucial that an excess of HPMe2 be used or the KPMe2 will be contaminated with unreacted KCH2C6H5.  The KPMe2 thus obtained was reacted with HN(SiMe CH Cl)2 as shown in 2  equation  3.3,  to  generate  the  necessary  2  potassium  ligand  salt,  K[N(SiMe2CH2PMe2)2l. in 66% isolated yield. The latter was reacted with YCI3 in THF (Equation 3.5), the KCI formed was filtered off, and the resulting clear, colourless solution was evaporated to dryness leaving a freely-running white powder.  After  washing with hexanes and drying in vacuo it was determined to be analytically pure YCl [N(SiMe2CH2PMe2)2]- Presumably, this compound is oligomeric in nature as it 2  is obtained as a hydrocarbon-insoluble, THF-free powder, probably due to the fact that the small size of the methyl groups at phosphorus are incapable of preventing oligomerization.  MCI3 + K[N(SiMe CH PMe )2] 2  2  THF •  2  24 hr  MCl [N(SiMe CH PMe ) ] + KCI [3.5] 2  2  2  2  2  M = Y, 10a Lu, 11a  The 3lp{lH} NMR spectrum of 10a (in QDcj/THF) obtained via eq. 3.5 was identical to that of the LiCl-contaminated material obtained in eq. 3.1. The conditions in reaction 3.5 have also been used successfully to prepare the lutetium analog, 11a. Both complexes display temperature independent NMR spectra in THF/C6D5CD3, that is, one sharp resonance (a doublet for yttrium) in the P { H ) NMR spectra both 31  1  at room temperature and at -90 °C. In addition to resonances for the large excess of THF (about 10 equivalents), each complex shows three resonances in their C!{lH} 13  72  and * H N M R methylene  spectra (i.e., the phosphorus-methyl hydrogens and carbons, the  protons and carbons and the s i l y l - m e t h y l hydrogens  respectively).  and  carbons  In C 6 D 5 C D 3 / T H F solutions, the coordination of two T H F molecules  (rapidly exchanging w i t h the bulk solvent) w o u l d generate a  seven-coordinate  monomer, which would have N M R spectra such as those observed (Figure  3.1).  In order to obtain hydrocarbon-soluble complexes, an attempt was made to metathesize the chlorides with several reagents.  substitution of a hydrocarbyl  The  ligand for a chloride should enhance solubility as w e l l as generate a reactive ligand on the metal.  H o w e v e r , the reactivity o f Y C l 2 [ N ( S i M e 2 C H 2 P M e 2 ) 2 L 10a,  was  somewhat disappointing. Attempts to alkylate this complex with a variety of reagents ( L i M e , L i C H 2 C M e 3 , K C H 2 C 6 H 5 ) invariably led to intractable mixtures. In order to gain some insight into the processes occurring, the reaction with two equivalents of benzylpotassium was monitored at 20 °C by doublet at -45.9  P { ! H } N M R spectroscopy. Initially, a  was observed (no signal for 10a  remained)  w h i c h disappeared after a few minutes to be replaced p r i m a r i l y by  resonances  attributable  p p m ^Jy.p  3 1  = 38.6)  to Y [ N ( S i M e C H P M e ) ( S i M e C H P M e ) ] [ N ( S i M e C H P M e ) 2 ] , 7a, 2  2  2  2  the cyclometallated complex discussed in Chapter 2.  2  2  2  2  A reasonable explanation is that  the i n i t i a l l y formed d i a l k y l complex, Y R 2 [ N ( S i M e 2 C H 2 P M e 2 ) 2 l is unstable and decomposition occurs v i a ligand metallation and disproportionation.  SiCH  73 Me  P.  Me Si' N 3  MeoSi  2  \THF  2  PCH  3  Lu" THF  P Me  2  SiCH P 2  J  \  ^T l^o'.'e  r  i  TTTTT  PCH  i i  i  i  '  0/4  i i ' i | i i i ' r•i  i i  i  i  iiii  i''  0.2 PPM  11  3  SiCH  3  SiCH P 2  4.V r  iii  i i  i|i'i r  18  16  1 '  4  '  "  12  10  8  6  20  Figure 3.1: NMR spectra of L u C l [ N ( S i M e C H P M e ) ] , H a : 300 MHz l H 2  2  2  2  2  spectrum (top) and 75.4 MHz 13C{*H} spectrum (bottom), both in C D C D / T H F . 6  The C6D5CD3 peak is marked with an asterisk.  5  3  74 3.3 Synthesis  and Structure of {Y(aIlyl)[N(SiMe2CH PMe )2]}2(u-Cl)2 2  2  The reaction of YCl [N(SiMe CH PMe ) ], 10a, with C3H MgCl was more 2  2  2  2  2  5  promising than the previously discussed alkylation attempts. With one equivalent of this Grignard reagent some decomposition did occur, but white crystalline product mixtures were obtainable.  Unfortunately, attempts to separate the products via  fractional crystallization proved futile. Reaction with two equivalents of CsHsMgCl led to a lemon yellow solution which contained some of the expected bis(allyl) complex, Y(allyl) [N(SiMe CH PMe ) ]. T h e ^ P p H ) NMR spectrum showed a 2  2  2  2  2  doublet at -38.3 ppm (Uy.p = 81 Hz) but this compound also could not be separated from the decomposition products present.  However, a straightforward preparation of a mono(ligand) allyl complex was discovered.  Reaction  of CsHsMgCl  with  the bis(ligand)  complex,  YCl[N(SiMe CH PMe ) ] , l a , produced the dimeric, mono(amido-diphosphine) 2  compound,  2  2  2  2  {Y(allyl)[N(SiMe CH PMe ) ]} (|I-C1) , 12a, which has been 2  2  2  2  2  2  crystallography characterized (See Tables 3.1 & 3.2 and Figure 3.2).  Table 3.1: Selected Bond Lengths for {Y(allyl)[N(SiMe CH PMe ) ]} (u-Cl) . 2  2  2  2  2  Bond  Length (A)  Bond  Length (A)  Y-Cl  2.746 (1)  Y-Cll  2.587 (5)  Y-Cl'  2.795 (1)  Y-C12  2.609 (5)  Y-Pl  2.931 (1)  Y-C13  2.621 (5)  Y-P2  2.892 (1)  C11-C12  1.387 (9)  Y-N  2.292 (4)  C12-C13  1.356 (8)  2  75 C12  Figure 3.2: Three views of {Y(allyl)[N(SiMe2CH PMe2)2]h(u-Cl)2,12a. At the 2  top are two Chem 3D® views; the figure at the top right shows the approximate pentagonal bipyramidal geometry at yttrium (based on the assignment of two coordination sites for the allyl moiety): the N and CI' atoms are axial while PI, P2, CI and the allyl are equatorial. The bottom view is the ORTEP stereoview showing the complete atom labelling scheme.  76 Table 3.2: Selected Bond Angles for {Y(allyl)[N(SiMe2CH PMe2)2]}2(u-Cl)2. 2  Bond  Angle (deg)  Bond Type  N-Y-Cl'  162.37 (10)  Ax-Y-Ax  Cl-Y-Pl  81.02 (4)  Eq-Y-Eq  N-Y-Cl  97.88 (9)  Ax-Y-Eq  C1-Y-P2  81.26 (4)  Eq-Y-Eq  N-Y-Pl  76.01 (10)  Ax-Y-Eq  P1-Y-P2  148.38 (4)  Eq-Y-Eq  N-Y-P2  80.75 (10)  Ax-Y-Eq  Pl-Y-A  100.7 (1)  Eq-Y-Eq  c  Ax-Y-Eq  P2-Y-A  104.3 (1)  Eq-Y-Eq  c  161.9 (1)  Eq-Y-Eqd  3  N-Y-A  100.0 (1)  b  Bond  3  Angle (deg) BondType  Cl'-Y-Cl  76.11 (4)  Ax-Y-Eq  Cl-Y-A  cr-Y-pi  118.52 (4)  Ax-Y-Eq  C11-C12-C13 126.1 (6)  Cl'-Y-P2  81.94 (4)  Ax-Y-Eq  Y-Cl-Y'  Cl'-Y-A  87.5 (1)  Ax-Y-Eq  b  103.89 (4)  a) A = centroid of the allyl moiety. b) Ax = axial; Eq = equatorial for the pentagonal bipyramidal geometry. c) As the allyl centroid "A" centres 2 coordination sites, ideally this angle should be 108° (72 + 36). d) As the allyl centroid "A" centres 2 coordination sites, ideally this angle should be 180* (144 + 36).  Assigning two coordination sites to the Tj3-allyl moiety makes the complex seven-coordinate  at each metal.  This arrangement is best described as two  pentagonal bipyramids fused together via two bridging chlorides; each chloride is axial on one metal and equatorial on the other. The amide ligands take up the other axial sites. In an ideal pentagonal bipyramid the axial-metal-axial angle is 180°, the axialmetal-equatorial angles are 90° and the equatorial-metal-equatorial angles are 72° or 144°. In the allyl complex the axial-Y-axial bond angle is 162.37°, a deviation of 17.6° from the ideal. The axial-Y-equatorial bond angles range from 76.01° to 118.52° but average to 89.8°, very close to the expected 90°. See Tables 3.1 and 3.2 for the bond lengths and angles.  77 This allyl complex is fluxional and undergoes fast syn-anti allyl exchange.  10  At  high temperature, the *H and C { H ) NMR spectra each show five resonances. One 13  1  signal for the central allyl proton (or its carbon), one signal for the equivalent syn and anti allyl hydrogens (or their carbons) and three signals for the amido-diphosphine ligand. However, syn-anti exchange does not completely explain the high symmetry of the NMR spectra (Figure 3.3). A fluxional process which equates both sides of the amido-diphosphine ligand must also be invoked.  If the compound maintains its  dimeric structure, then the simplest explanation is that phosphine donors exchange sites via dissociation, rotation about the metal amide bond and phosphine recoordination.  At low temperature, the NMR spectra are in agreement with the X-ray structure. The Hi, C{ H) l3  l  and P { H ) NMR spectra are consistent with C h 31  1  2  symmetry (i.e., in solution and at low temperature one would expect the dimer to have a C axis not present in the molecular structure) and reflect the inequivalent 2  environments on either side of tridentate ligand plane. There are two signals for the phosphorus methyl protons and carbons, two for the silyl methyl hydrogens and carbons, two resonances for the methylene protons and one signal for the methylene carbons. The syn-anti exchange of the allyl moiety is frozen out such that two carbon and three proton resonances, showing resolved Figure 3.3). A doublet  ( JY-P !  regardless of the temperature.  3  JH-H  couplings, are present (See  = 82 Hz) is observed in the P{ H} NMR spectrum 31  l  Figure 3.3 300 MHz H NMR spectra of {Y(allyl)[N(SiMe CH PMe2)2] h(H-Cl)2, J  2  2  12a, at + 80 °C (top) and at -50 °C (bottom) in C6D5CD3 (marked with asterisks).  79  The formation of {Y(allyl)[N(SiMe CH PMe2)2]}2(H-Cl)2,12a, from allyl2  2  MgCl and YCl[N(SiMe2CH2PMe2)2] , la, was somewhat puzzling. The reaction 2  was done in THF and worked up in toluene; extraction of the crude reaction mixture with toluene gave a clear colourless solution free of any precipitates. When this reaction was monitored by P{ H} NMR spectroscopy the spectrum showed the 31  1  presence of two phosphorus containing compounds, a doublet for the allyl dimer and a singlet at -57 ppm due to an unknown compound. It seemed reasonable that, based on mass balance, this reaction gave two products, the allyl dimer and the new complex MgCl[N(SiMe2CH PMe )2] (Equation 3.6). 2  2  + C H MgCl 3  YCl[N(SiMe2CH PMe )2] 2  2  5  MgCl[N(SiMe CH PMe2)2] + 2  2  [3.6]  2  1/2 {YCl(allyl)[N(SiMe CH PMe ) ]} 2  2  2  2  2  However, the elemental analysis for the allyl complex did not agree with this formulation and on standing, solutions of this compound deposited some insoluble material. When crystals of "MgCl[N(SiMe2CH2PMe2)2l" were isolated, they gave an elemental analysis consistent with a formulation as Mg[N(SiMe2CH2PMe2)2l2The analysis of the recrystallized allyl complex was now reinterpreted as indicating the presence of MgCl2-  A formulation of {YCl(allyl)[N(SiMe2CH2PMe2)2]h-  (MgCl2)o.7 fit the data and indicated that MgCh was the insoluble material that slowly precipitated from solution. This then implied that the products of the reaction are  {Y(allyl)[N(SiMe2CH PMe2)2] h(u-CT) , Mg[N(SiMe CH PMe2)2]2 and 2  2  2  2  MgCb (Equation 3.7).  2YCl[N(SiMe CH PMe ) ] 2  2  2  2  2  [3.7]  80 It is possible that the reaction proceeds initially via an exchange of ligands between the magnesium and yttrium metals (an allyl moiety for an amido-diphosphine ligand) followed by disproportionation of the MgCl[N(SiMe2CH2PMe2)2] to give Mg[N(SiMe2CH2PMe2)2l2  a n  d MgCl2-  The monomelic yttrium allyl complex,  YCi(allyl)[N(SiMe2CH2PMe2)2L could then either dimerize to give 12a or coordinate the MgCl to giveYCl(allyl)[N(SiMe CH2PMe )2](MgCl2). 2  2  2  To test the validity of equation 3.7, Mg(allyl)2(dioxane) was synthesized and reacted with 2 equivalents of YCl[N(SiMe2CH2PMe2)2l2» l a .  As expected  {Y(allyl)[N(SiMe CH2PMe2)2]}2(H-Cl)2, 12a, and Mg[N(SiMe CH PMe2)2]2 2  2  2  were formed (Equation 3.8). Both complexes gave satisfactory elemental analyses and identical NMR data to that recorded for the compounds isolated using equation 3.7.  Mg(/\^) 2YCl[N(SiMe CH PMe ) ] 2  2  2  2  2  Mg[N(SiMe CH PMe ) ]2 + 2  2  2  2  •  2  THF  [3.8] {YCl(allyl)[N(SiMe CH PMe ) ] } 2  2  2  2  2  The allyl dimer could now be prepared pure and in high yield; unfortunately it had disappointing reactivity. presence of ethylene.  It did not react with H2 and it decomposed in the  However, the ability of the allyl ligand to stabilize a  mono(amido-diphosphine) complex had been demonstrated.  This made the diallyl  complex, Y(allyl)2[N(SiMe CH2PMe2)2]» 13a, the next target molecule, as it should 2  be a seven-coordinate monomer and also contain two-reactive hydrocarbyl ligands.  81  Y ( a l l y l ) 2 [ N ( S i M e 2 C H 2 P M e 2 ) 2 L 13a, Mg(allyl)2(dioxane) reagent (Equation 3.9).  was synthesized  using the  As already mentioned, a previous  attempt to make this molecule using (allyl)MgCl had resulted in formation of an inseparable mixtures of products.  M g ( ^ ) YCl [N(SiMe CH PMe )2] 2  2  2  2  •  2  Y(allyl) [N(SiMe CH PMe ) ] [3.9] 2  2  2  2  2  THF -(MgCl ) 2  The lemon yellow diallyl complex is extremely soluble in hexanes and could not be induced to crystallize even though NMR spectra on the crude reaction material indicated that a very clean reaction with little or no decomposition had occurred. Consequently, this complex has only been characterized by NMR spectroscopy. Apart from syn-anti exchange for the equivalent allyl ligands this compound displays temperature independent NMR behaviour.  The reactivity of H2 and ethylene with Y(allyl)2[N(SiMe2CH2PMe2)2] has been investigated.  The thermolysis of Y(allyl)2[N(SiMe2CH2PMe2)2]»  13a, in a  sealed NMR tube at 95° C for two days under approximately four atmospheres of H2 resulted in the complete disappearance of the diallyl complex. The resulting NMR spectra were complex and indicated that a number of species were present. The  1  1  cyclometallated Y[N(SiMe CHPMe )(SiMe CH PMe )][N(SiMe CH PMe ) ], 7a, 2  2  2  2  2  2  2  2  2  bis(ligand) complex was the major product and a transitory hydride species (indicated by a doublet of pentets at +3.9 ppm in the *H NMR spectrum) could also be identified. Exposing just the diallyl complex to the same conditions (95 °C for 2 days) resulted in only a partial conversion (< 10% by NMR) to the cyclometallated bis(ligand) complex and no hydride formation, thus demonstrating the thermal stability of this bis(allyl)  82  complex.  A sealed NMR tube of Y(allyl)2[N(SiMe2CH2PMe2)2l. 13a, under  approximately 1 atmosphere of ethylene (at room temperature) produced some crystalline polyethylene, but the NMR spectra only showed the presence of 13a, thus, the nature of the catalyst remains unknown. These are somewhat promising results as they show that given therighthydrocarbyl ligands Y(R)2[N(SiMe2CH2PMe2)2] complexes can be moderately thermally stable and can undergo hydrogenolysis to generate hydride species (albeit unstable hydrides). It is also possible that these complexes may be polymerization catalysts. i 1  However, the formation of  Y[N(SiMe CHPMe )(SiMe CH PMe )][N(SiMe CH PMe ) ], 7a, can still occur 2  2  2  2  2  2  2  2  2  and seems to be problematic for any reactivity of complexes containing this particular amido-diphosphine ligand. 3.4  Syntheses of YCl [N(SiMe CH PR2)2] R = Ph, Bu*, Pr 2  2  5  2  Although some success had been achieved with the mono(amido-diphosphine) complexes incorporating the [N(SiMe CH PMe )2l" ligand, there were two 2  2  2  drawbacks: (i) the insolubility of the dichloride complex and (ii) the tendency of the alkylated derivatives to disproportionate and decompose. Therefore, the next phase of this project was to attempt to make more soluble mono(ligand) complexes by using ligands with bulkier phosphine donors. The basic idea was that large substituents at phosphorus would prevent higher order oligomers from forming and that greasy alkyl groups at phosphorus would aid in solubility. In addition, by bulking up the phosphine donor it might be possible to isolate complexes that would be unstable if the less bulky [N(SiMe2CH2PMe2)2l" ligand were used.  The same strategy used for the formation of YCl2[N(SiMe2CH2PMe2)2L 10a, was employed.  Two new ligands, K [ N ( S i M e 2 C H 2 P R 2 ) 2 l (R = Bu , Ph) were l  83  synthesized (Equations 3.10 and 3.11); the KPBu 2 used was synthesized from l  benzylpotassium and HPBu^. THF 3KPBu + HN(SiMe CH Cl)  • K [ N ( S i M e C H P B u ) ] + HPBu [3.10]  l  2  2  2  t  2  2  2  2  2  2  -2 KCI THF KCH C H 2  6  5  + HN(SiMe2CH PPh ) 2  2  •  2  - C H 7  K[N(SiMe CH PPh ) ] 2  2  2  [3.11]  2  8  Both of these potassium salts reacted with YCI3 to give poor yields of toluene soluble complexes, 10b and lOd, that tended to crystallize as THF adducts (Equation 3.12). The complex with phenyl substituents at phosphorus was isolated as a THF adduct while for lOd, the first crop of crystals contained THF and the later batches of crystals contained little or no THF. Repeated recrystallization from toluene enabled removal of the THF, but the yields of pure complex were unsatisfactory. THF YCI3  + K[N(SiMe CH PR ) ] 2  2  2  •YCl [N(SiMe CH PR ) ](THF) [3.12]  2  2  2  2  2  2  n  -KCI R = Ph  10b  R = Bu lOd l  These complexes were not further investigated because a superior route to a soluble mono(ligand) compound was discovered.  The reaction of YCI3 with the lithium salt of the ligand having isopropyl groups at phosphorus, Li[N(SiMe2CH2PPr 2)2L gave the desired complex in high yield J  (Equation 3.13).  Separation from the LiCl byproduct was possible as this  mono(ligand) complex is hexanes soluble.  84 THF  YC1 + Li[N(SiMe CH PPr ) ] 1  3  2  2  2  •YCl [N(SiMe CH PPr ) ](THF) [3.13] 2  2  2  2  2  2  -LiCl  n  10c  The first two crops of crystals isolated were THF adducts, while the rest of the compound was isolated base free. A molecular weight determination of the THF-free complex showed it to be the dimer { Y C h t N C S i h ^ C ^ P P r ^ h l h ,  10c  > at 20 °C in  C6D6. This dimer shows a doublet (Jy.p = 88 Hz) in its P{ H) NMR spectrum at 31  l  all temperatures (+20 to -80 °C). The *H NMR spectra are somewhat different. At room temperature a highly symmetric spectrum is observed; one silyl methyl, one methylene, one isopropyl methine and two isopropyl methyl resonances are present (Figure 3.4).  At -78 °C the *H NMR spectrum is broad, but two silyl methyl  environments can be discerned.  Based on these data, there are two reasonable  dimeric structures. A six-coordinate, dichloride bridged dimer, A, is consistent with the H NMR spectrum obtained at low temperature, whereas a seven-coordinate, J  tetrachloride bridged dimer, B, explains the NMR data obtained at room temperature. A fluxional process whereby at high temperature A interconverts bridging and terminal chlorides via B also fits the data. Alternatively, compound A could be undergoing phosphine dissociation-reassociation equilibria. A rapid monomer-dimer equilibrium is unlikely as the molecular weight determination demonstrated that this complex was dimeric at 20 °C.  Me Si 2  Me Si 2  A  B  Figure 3.4: Temperature invariant NMR spectra of {YCl2[N(SiMe2CH2PPr 2)2]h. i  10c in C D : 6  6  121 MHz 31p{lH) NMR spectrum (top) and 300 MHz *H NMR  spectrum (bottom).  86  The isolated THF adduct, YCl [N(SiMe2CH PPr 2)2](THF), has a very i  2  2  complex NMR behaviour (different from that displayed by the base free complex) as shown by its variable temperature P{!H} NMR spectra (Figure 3.5). In C6D5CD3 31  at +60 °C there is only one doublet (Jy.p = 89 Hz) present. As the temperature is lowered to 20 °C coalescence occurs and at -34 °C the presence of three species is indicated by three doublets of 91, 87 and 73 Hz in a ratio of 74%, 13% and 13% respectively;  because the nuclearity of these species is unknown the actual  concentrations were not determined. As the temperature is lowered further, signal collapse occurs again and at -79 °C only two compounds are present, as indicated by two doublets of 92 and 73 Hz in ratios of 89% and 11%.  If a large excess of THF is added to the C 6 D 5 C D 3 YCl2[N(SiMe CH PPr 2)2](THF) the observed behaviour changes. i  2  2  solution of The 31p{lH)  NMR spectra now show just one doublet (Jy.p = 75 Hz) from high temperature down to -20 °C. Coalescence occurs around -50 °C, but even down to -100 °C, the low temperature limit is not achieved and broad complex signals are observed. While the effect of addition of THF was not quantified, it is reasonable to assume that equilibria involving the transfer of THF between yttrium and the bulk solvent is occurring. A number of reasonable structures may be postulated. At high temperature, addition of THF should favor a seven coordinate bis(THF) monomer that exchanges coordinated THF with free THF in the solvent mixture.  At lower temperatures where THF  exchange could be slow, mono(THF) adducts or even dimers with variable amounts of coordinated THF could be present.  87  +60 *C  -79°C  Figure 3.5:  121 MHz  3 1  P{ H) 1  variable temperature  YCl2[N(SiMe CH PPr 2)2](THF) in C D C D . i  2  2  3  6  5  NMR spectra of  88  3.5  Synthesis and Thermolysis of Y C l ( P h ) [ N ( S i M e C H P P r » ) 2 ] 2  2  2  YCl [N(SiMe CH PPr ) ](THF) was reacted with 2.1 equivalents of LiPh in i  2  2  2  2  2  an attempt to generate the diaryl complex YPh [N(SiMe CH PPr ) ]. A low yield of i  2  2  2  2  2  some colourless crystals was isolated, tentatively assigned as the monophenyl derivative  Y C l ( P h ) [ N ( S i M e C H P P r i ) ] , 14c. 2  2  2  2  This compound was only  characterized by ^H, ^ C p H } and P{ H} NMR spectroscopy, and shows highly 31  1  symmetric temperature-invariant spectra (Figure 3.6).  A C6D5CD3 solution of 14c in a sealed NMR tube slowly changed from colourless to yellow over a period of weeks at room temperature. The P{ H} NMR 31  1  spectrum showed that a new complex with resonances for four inequivalent phosphines was slowly growing in, while the *H NMR spectrum indicated that C^H6 was being formed. A ligand metallation reaction between two monomelic units is a possible reaction. Heating the tube to 47 °C for two weeks resulted in a complete conversion of 14c to this new complex. The P{ H} NMR spectrum (Figure 3.7) 31  ]  shows 4 inequivalent phosphines, and the core geometry shown in the figure fits the data. P at 34.6 ppm is only coupled to one Y atom (39.1 Hz). Pi at 44.5 ppm is 2  coupled to P3 (7.1 Hz), P4 (7.1 Hz) and two Y atoms (47.7 and 12.4 Hz). P3 and P4 at 12 and 13 ppm are not coupled to each other (therefore cisoid) but are coupled to Pi (7.1 and 7.1 Hz) and one Y atom (61.2 and 63.1 Hz). The structure shown in Figure 3.7 has each metal centre as being 6 coordinate. Another possibility is to have the phenyl group bridge both metals generating a dimer with one 7-coordinate and one 6coordinate centre.  89  Figure 3.6: Temperature invariant NMR spectra of YCl(Ph)[N(SiMe2CH2PPri2)2J, 14c, in C D C D . 3  6  5  121 MHz 3lp{lHJ NMR spectrum (top) and 300 MHz *H NMR  spectrum (bottom). The CD3C6D5 resonances are marked with an asterisk.  90  Figure 3.7: 121 MHz P{ H} NMR spectra (in CD3C6D5) of 15c and a possible 31  structure for this complex.  1  91  This new complex is interesting in that only mono(ligand) metallation has occurred, and the remaining phenyl group shows no tendency to abstract another ligand proton. The reactivity of this complex could be of great interest and perhaps it will prove to be more versatile than the cyclometallated bis(amido-diphosphine) complex discussed in Chapter 2.  3.6 Summary  The synthesis of a number of mono(amido-diphosphine) lanthanoid complexes has been achieved.  As expected, these species were more complex than the  bis(amido-diphosphine) compounds described in Chapter 2. Complexes of the type MCl2[N(SiMe2CH2PMe2)2l are insoluble in hydrocarbon solvents, presumably because they are oligomeric in nature. They will, however, dissolve in THF probably forming seven-coordinate bis(THF) monomers.  Attempts to alkylate these  compounds generally led to decomposition; the cyclometallated bis(ligand) complex i 1 Y[N(SiMe CHPMe )(SiMe CH PMe )][N(SiMe CH PMe ) ], 7a, was identified as 2  2  2  2  2  2  2  2  2  the major product. A route to a dimeric mono(amido-diphosphine) allyl complex, {YCl(allyl)[N(SiMe2CH2PMe2)2]h was found via the reaction of allyl-MgCl or Mg(allyl) (dioxane) with YCl[N(SiMe2CH2PMe )2k2  2  The diallyl compound  Y ( a l l y l ) 2 [ N ( S i M e 2 C H 2 P M e 2 ) 2 ] was also synthesized, demonstrating that bis(hydrocarbyl) complexes can be stabilized on a Y[N(SiMe2CH2PMe2)2] fragment. Unfortunately the diallyl compound could not be purified, and when it was allowed to react with H2, decomposition occurred with formation of 7a as the major product.  In an attempt to isolate hydrocarbon-soluble mono(amido-diphosphine) complexes, three yttrium compounds containing bulky phosphine donors were synthesized:  YCl2[N(SiMe CH PR2)2]. R = Ph, Bu , Pr . The complex with l  2  2  1  92  isopropyl groups at phosphorus was synthesized in good yield. This hexanes soluble isopropyl derivative can be isolated as either a THF adduct or as the base-free dimer. It can be derivatized, probably generating YCl(Ph)[N(SiMe2CH2PPr 2)2l» which is i  thermally sensitive and undergoes a cyclometallation reaction (losing C6Hg) to form I 1  Y Cl (Ph)[N(SiMe CHPPr )(SiMe CH PPr )][N(SiMe CH PPr ) ], 15c. ,  2  2  2  3.7  1  2  2  2  1  2  2  2  2  2  Experimental Procedures  3.7.1  General Information. The same general procedures as outlined in section  2.8.1 were followed.  3.7.2  KPMe2.  H P M e 2 was vacuum transferred into a tared, evacuated heavy-  walled Schlenk tube and its weight determined (9.02 g, 0.145 mol). This H P M e 2 was then vacuum transferred onto a cold (-78 °C) THF solution (120 mL) of K C H 2 C 6 H 5 (12.5 g, 0.0960 mol) and slowly allowed to warm to room temperature. The bright orange colour of the THF solution immediately becomes dark orange brown. After warming to room temperature most of the volatiles were removed in vacuo. In order to prevent a solid mass from forming, toluene (50 mL) was added, the mixture stirred for a few minutes and then evaporated to dryness. The flask was then removed to a glovebox, the solid was scraped out of the flask, washed several times with hexanes and dried in vacuo. The yield of off-white K P M e 2 (9.19 g, 0.0918 mol) based on K C H C H used was 96%. 2  3.7.3  6  5  K[N(SiMe CH PMe )2]. 2  2  2  HN(SiMe CH Cl) (3.63 mL, 16.6 mmol) was 2  2  2  slowly added dropwise to a cooled (-10 °C) THF solution (100 mL) of KPMe (5.00 g, 2  49.9 mmol) with good stirring. During the addition the dark red colour due to the phosphide faded to a pale yellow colour. The THF was removed in vacuo and the  93  resulting glass was extracted with hexanes (150 mL), and filtered through a thick pad of Celite® to remove the gelatinous KCI. cooling to -30 °C yielded 3.50  Concentrating the hexanes solution and  g (66% yield) of colourless  crystalline  K[N(SiMe CH PMe )2]. *H N M R : 8 1.00 (12H, s, PMe), 0.67 (4H, d, J = 4.2, 2  2  2  PCH Si) and 0.18 (12H, s, SiMe). 3 C { H } N M R : 8 25.92 (d, J = 20.5, PCH Si), 1  1  2  2  17.54 (d, J = 9.4, PMe) and 7.86 (s, SiMe). 31p{lH} N M R :  8 -56.5 (s).  Anal.  Calcd. for C i H N P S i K : C, 37.59; H, 8.83; N, 4.38. Found: C, 37.80; H, 9.00; N, 0  28  2  2  4.51.  3.7.4  K[N(SiMe CH PPh ) ]. K C H C H (0.80 g, 6.14 mmol) in 25 mL of THF 2  2  2  2  2  6  5  was slowly added dropwise to a cooled (-10 °C) THF/toluene solution (100 mL) of HN(SiMe CH PPh ) (3.25 g, 6.14 mmol) with good stirring. The deep orange colour 2  2  2  2  due to the benzylpotassium is discharged as it deprotonates the amine leaving a yellow solution. The THF/toluene was removed in vacuo and the resulting glass was extracted with toluene (150 mL), and filtered through Celite® to remove any unreacted benzylpotassium. Concentrating the toluene solution, adding hexanes (50 mL)  and cooling  to -30  °C yielded  3.0  g  (86%  yield)  of powdery  K[N(SiMe CH PPh ) ]. * H N M R : 8 7.52 (8H, m, HQ), 7.07 (12H, m, H & H ), 2  2  2  2  m  I. 48 (4H, d, J = 3.2, PCH Si) and 0.06 (12H, s, SiMe).  1 3  2  p  C N M R : 8 142.22 (d, J =  II. 0, CO, 132.99 (d, J = 18.6, C ), 128.50 (d, J = 12.2, C ) , 128.49 (s, C ), 20.29 (d, J Q  m  p  = 26.4, PCH Si) and 7.82 (d-3.9 Hz, SiMe). 31p{lH} N M R : 8 -20.0. Anal. Calcd. 2  for C3oH NP Si K: C, 63.46; H, 6.39; N, 2.47. Found: C, 63.57; H, 6.48; N, 2.30. 36  3.7.5  2  2  KP(Bu*) . HPBut (10.15 g, 69.42 mmol) was syringed onto a cold -78 °C 2  2  THF/hexanes solution (120 mL) of K C H C H 2  6  5  (8.55 g, 65.65 mmol) and slowly  allowed to warm to room temperature. The bright orange colour of the THF solution immediately becomes dark greenish brown. After warming to room temperature the  94  volatiles were removed in vacuo and a white crystalline mass formed. The flask was left under vacuum overnight and the following day hexanes (60 mL) was added, the mixture stirred for a 30 minutes and then evaporated to dryness. The flask was then removed to a glovebox, the solid was scraped out of the flask, washed several times with hexanes and dried in vacuo. The yield of KPBu^ (11.14 g, 60.44 mmol) based on K C H C 6 H used was 92%. 2  5  K[N(SiMe CH PBu 2)2]. In a 250 mL flask, KPBu^ (7.61 g, 41.3 mmol)  3.7.6  T  2  2  was suspended in hexanes and cooled to -10 °C. THF (100 mL) was slowly added to the phosphide suspension resulting in a greenish-brown solution. To this solution H N ( S i M e C H C l ) (3.00 mL, 13.8 mmol) was slowly added dropwise. After the 2  2  2  addition, the solution was warmed to room temperature and allowed to stir for 2 hours prior to evaporation of the THF.  The resulting glass was extracted with hexanes,  filtered through Celite® and the filtrate cooled to -30 °C to yield 3.20 g of K[N(SiMe CH PBut ) ] (48%). *H NMR: 2  2  2  2  1.14 (36H, d, J = 11.1, PCMe), 0.66  (4H, d, J = 7.5, PCH Si) and 0.42 (12H, s, SiMe). 2  *3c{lH} NMR:  8 33.20 (s,  PCMe ), 29.93 (d, J = 12.9, PCMe ), 13.06 (d, J = 18, PCH Si) and 7.52 (s, SiMe). 3  3  2  31P{lH} NMR: 8 19.0 (s). Anal. Calcd. for C H N P S i K : C, 54.16; H, 10.74; N, 2 2  5 2  2  2  2.87. Found: C, 53.80; H, 10.74; N, 2.70.  3.7.7  Mg(alIyl) (dioxane).  The synthesis of this compound is based on that  2  reported for M g ( C H S i M e ) . 2  3  2  11  To a THF solution (60 mL) of (allyl)MgCl (0.0614  mol) was slowly added 1,4-dioxane (10 mL), and the solution allowed to stir overnight.  The following day the stirring was stopped and the suspension of  MgCl (dioxane) was allowed 6 hrs to settle out from the solution. 2  The clear  supernatent solution was cannula filtered to another flask and the solvent evaporated to dryness leaving a white powder. This powder was dried overnight under vacuum  95 and elemental analysis showed it to be a dioxane adduct. NMR spectrum reported in C D miF. The yield of Mg(allyl) (dioxane) (2.24 g) was 19%. *H NMR: 6.51 6  6  2  (IH, p, J = 12.2, H ) and 2.65 (4H, d, J = 12.2, H , H ) . m  s  m  Anal. Calcd. for  CioH Mg0 : C, 61.74; H, 9.32. Found: C, 61.60; H, 9.30. 18  2  LuCI [N(SiMe CH PMe2)2l» Ha* In a glovebox, an apparatus designed  3.7.8  2  2  2  for filtering under N , was charged with LuCl3 (0.440 g, 1.56 mmol) and 2  K[N(SiMe CH PMe ) ] (0.500 g, 1.56 mmol). Celite® was added to the filter pad 2  2  2  2  and held in place with a wad of cotton wool. The apparatus was sealed under N , 2  removed from the glovebox, placed on a vacuum/nitrogen line and THF (100 mL) was added to the solids. This mixture was allowed to stir for 1 hour before filtering off the KCI generated. The filtrate was evaporated to dryness (leaving a freely-flowing white powder), the whole apparatus was sealed under vacuum and removed to the glovebox. The white powder was washed with hexanes and dried under vacuum to yield 0.423 g of LuCl [N(SiMe CH PMe ) ] (52% yield). 2  2  C D CD /THF 6  5  2  2  IH NMR:  3  2  NMR spectra are reported in  6 1.05 (12H, t, J = 2.1, PMe), 1.00 (4H, t, J = 3.1,  PCH Si) and 0.31 (12H, s, SiMe). ^C^H} NMR: 8 19.31 (s, PCH Si), 13.93 (t, J 2  2  = 3.1, PMe) and 6.15 (s, SiMe).  31  P{lH} NMR:  8 -34.1 (s). Anal. Calcd. for  CioH NP Si LuCl : C, 22.82; H, 5.36; N, 2.66. Found: C, 23.13; H, 5.20; N, 2.90. 28  2  2  2  YCI [N(SiMe CH PMe2)2L 10a. The same procedure as for the above  3.7.9  2  2  2  compound was used.  YCI3 (0.665 g, 3.41  mmol) was reacted with  K[N(SiMe CH PMe ) ] (1-088 g, 3.40 mmol) to give 1.40 g (93% yield) of 2  2  2  2  YCl [N(SiMe CH PMe ) ]. 2  2  2  2  2  NMR spectra are reported in C6D5CD3/THF *H  NMR: 8 1.04 (12H, t, J = 1.9, PMe), 1.02 (4H, t, J = 2.8, PCH Si) and 0.30 (12H, s, 2  SiMe).  13  C{!H} NMR: 8 19.75 (s, PCH Si), 14.06 (s, PMe) and 6.34 (s,SiMe). 2  96  3lp{lH} NMR: 5 -41.8 (d, J = 77). Anal. Calcd. for CioH 8NP Si2YCl2: C, 27.28; 2  2  H, 6.41; N, 3.18; CI, 16.11. Found: C, 27.50; H, 6.50; N, 3.08; CI, 15.95.  3.7.10 Y C l [ N ( S i M e C H P P h ) ] , 10b. The same procedure employed for the 2  2  2  2  2  synthesis of Y C l [ N ( S i M e C H P M e ) ] was used except that the product was 2  2  2  2  2  dissolved in minimum toluene and precipitated by the addition of hexanes. YCI3 (0.250 g, 1.28 mmol) was reacted with K[N(SiMe CH PPh ) ] (0.727 g, 1.28 mmol) 2  2  2  2  to give 0.482 g of this compound isolated as a THF adduct (49% yield). * H NMR: 8 7.66 (8H, broad, H ), 7.04, (12H, broad, H , H ), 3.44 (4H, broad, THF-a), 1.85 (4H, 0  m  p  broad, PCH Si), 1.02 (4H, broad, THF-0), and 0.11 (12H, s, SiMe). 2  3 P{ H} 1  1  NMR: 8 -15.7 (d, J = 68.7) and -11 (broad). This compound has not been isolated in analytically pure form.  3.7.11  Y C l [ N ( S i M e C H P P r ) ] , 10c. A Schlenk tube was charged with !  2  2  2  2  2  Y C I 3 (0.793 g, 4.06 mmol), Li[N(SiMe CH PPri ) ] (1.623 g, 4.061 mmol) and THF 2  2  2  2  (50 mL). The flask was sealed under N and stirred 24 hrs. Then the THF was 2  evaporated off and the resulting glass was extracted with toluene and filtered through a medium frit. The pale yellow filtrate was concentrated, cooled to -30 °C and several crops of crystals were collected.  The first two crops of crystals contained one  equivalent of THF, YCl [N(SiMe CH PPri ) ](THF) (1.030 g, 41% yield). * H 2  2  2  2  2  NMR: in C D C D 8 3.90 (4H, broad, THF-a), 1.96 (4H, broad, PCHMe ), 1.41 6  5  3  2  (4H, broad, THF-p), 1.24 (12H, d of d, J = 7.2 & 13.9, PCHMe), 1.14 (12H, d of d, J = 7.3 & 13.6, PCHMe), 1-02 (4H, m, PCH Si) and 0.42 (12H, s, SiMe). 2  NMR:  1 3  C{!H}  8 70.44 (s, THF-a), 25.36 (s, THF-J3), 23.30 (s, P C H M e ) , 19.89 (s, 2  PCHMe). 19.46 (s, PCHMe). 9.87 (t, J = 4.9, PCH Si) and 6.16 (s, SiMe). a i P ^ H } 2  NMR: in C D C D at 20 °C 8 0.0 (broad); at + 60 °C 8 1.8 (d, J = 89). After drying 6  5  3  on a vacuum line overnight these crystals gave an elemental analysis consistent with  97  a formulation of Y C l 2 [ N ( S i M e 2 C H P P r 2 ) 2 ] ( T H F ) . 4 . i  Anal. Calcd. for  0  2  C oH54NP2Si2Y(C H 0)o.4: C, 40.50; H , 8.18; N, 2.41. Found: C, 40.37; H, 7.88; N, 3  8  4  2.20.  The 3 , 4 rd  th  and 5  crops of crystals were the base free dimer  th  {YCl [N(SiMe CH PPri ) ]} (1.060 g, 47% yield). Molecular Weight Calcd.: 2  2  2  2  2  2  8 2.05 (4H, m, PCHMe ), 1.28 (12H, d of  1105 g/mol; Found: 1107 g/mol. *H NMR:  2  d, J = 7.2 & 13.5, PCHMfi), 1.21 (12H, d of d, J = 7.2 & 13.2, PCHMeJ, 1-02 (4H, d, J = 4.8, PCH Si) and 0.38 (12H, s, SiMe).  31  2  P{*H} NMR:  8 -0.2 (d, J = 87.9). Anal.  Calcd. for C i 8 H 4 4 N P 2 S i 2 Y C l : C, 39.13; H, 8.03; N, 2.54. Found: C, 39.35; H, 8.19; 2  N, 2.42.  3.7.12  YCl [N(SiMe2CH PBu 2)2], 2  10d. This compound was synthesized in  t  2  the same manner as Y C l [ N ( S i M e 2 C H 2 P M e 2 ) 2 l  except that the product was  2  recrystallized from toluene.  YCI3 (167 mg, 0.855 mmol) was reacted with  K[N(SiMe2CH2PBu 2)2] (417 mg, 0.855 mol). The first crop of crystals contained one t  equivalent of THF, (0.030 g) for a 5% yield of YCl2[N(SiMe2CH PBut2)2](THF). l H 2  NMR: (36H, 13  in C D C D 8 4.05 (4H, broad, THF-a), 1.40 (4H, broad, THF-p), 1.28 6  5  3  d, J = 12.3, PCMe), 1.04 (4H, d, J = 5.1, PCH Si) and 0.49 (12H, s, SiMe). 2  8 70.4 (s, THF-a), 32.68 (s, P £ M e ) , 29.99 (m, PCMe ), 25.27  C{!H} NMR:  3  3  31p{lH} NMR: in  (s, THF-p), 13.06 (broad, PCH Si) and 6.62 (s, SiMe). 2  C6D5CD3 8 21.9 (d, J = 87). After drying overnight under vacuum this compound gave an elemental analysis formulation as YCl [N(SiMe CH PBu ) ](THF)o.7. Anal. t  2  2  2  2  2  Calcd. for C H N P S i Y C l ( C H 0 ) o . 7 : C, 45.20; H, 8.81; N, 2.13. Found: C, 2 2  5 2  2  2  2  4  8  45.16; H, 8.89; N, 2.20. The base free complex, YCl [N(SiMe CH PBu ) ] (0.140 g, t  2  27% yield) crystallizes last. *H NMR: = 5, PCH Si) and 0.36 (12H, s, SiMe). 2  2  2  2  2  1.21 (36H, d, J = 12.9, PCMe), 0.76 (4H, d, J 31  P{*H} NMR:  8 19.6 (d, J = 93.3).  98  3.7.13  Mg[N(SiMe CH PMe2)2]2, {YCl(aIlyl)[N(SiMe CH PMe )2]}2, 2  2  2  2  2  12a. In a glovebox, a Schlenk tube was charged with YCl[N(SiMe CH PMe ) ] 2  2  2  2  2  (0.200 g, 0.292 mmol) and Mg(allyl) (dioxane) (28 mg, 0.14 mmol). The Schlenk tube 2  was removed from the glovebox and attached to a vacuum/nitrogen line. THF (50 mL) was added onto the two solids and the solution was stirred for 30 minutes. The THF was removed in vacuo (resulting in formation of a white crystalline mass), the flask was sealed under vacuum and taken into the glovebox.  The crystalline mass was  extracted with toluene to give a slightly murky solution which was filtered and concentrated to about 20 mL. The solution was cooled to -30 °C and the first crop of crystals (0.104 g, 76% yield) was {Y(u-Cl)(allyl)[N(SiMe CH PMe ) ]} ,12a. 2  2  2  2  2  NMR spectra are reported in C6D5CD3. *H N M R : 8 at +80 °C, 6.15 (IH, p, J = 13, H ) , 3.15 (4H, broad, H , H ), 1.18 (12H, s, PMe), 0.70 (4H, s, PCH Si) and 0.14 m  s  a  2  (12H, s, SiMe); at +20 °C, 6.19 (IH, sept, J = 12, H ) , 3.64 (2H, broad, H ), 2.83 m  s  (2H, broad, H ), 1.13 (12H, s, PMe), 0.65 (4H, s, PCH Si) and 0.18 (12H, s, SiMe); a  2  at -50 °C, 6.30 (IH, t of t, J = 8.6 & 15.6, H ) , 3.75 (2H, d, J = 8.6, H ), 2.95 (2H, d, J m  s  = 15.6, H ), 1.14 (6H, s, PMe), 1.04 (6H, s, PMe), 0.69 (2H, s, PCH Si), 0.64 (2H, s, a  2  PCH Si) , 0.31 (6H, s, SiMe) and 0.23 (6H, s, SiMe).  13  2  C{!H} NMR:  [UC-H] &  144.24 (s, Q ) [d, 143.5], 72.68 (s, C ) [t, 150.1], 20.09 (s, PCH Si) [t, 120.9], 15 G  2  (broad, PMe) and 6.34 (s, SiMe) [q, 117.1].  31  P{*H} N M R :  8 -39.7 (d, J = 81.8,  major), -41.5 (d, J = 75.8, minor). Anal. Calcd. for C i H N P S i Y C l : C, 35.02; H, 3  3 3  2  2  7.46; N, 3.14; CI, 7.95. Found: C, 35.40; H, 7.52; N, 3.16; CI, 7.71. The second crop of crystals obtained were Mg[N(SiMe CH PMe ) ] (0.065 g, 76% yield). * H N M R : 2  2  2  2  2  8 0.95 (12H, s, PMe), 0.61 (4H, t, J = , PCH Si) and 0.35 (12H, s, SiMe). "Cf^H} 2  NMR:  8 20.87 (s, PCH Si), 15.28 (s, PMe) and 7.05 (s, SiMe). 2  3  *P{lH} N M R :  8 -55.7 (s). Anal. Calcd. for C oH 6N P Si4Mg: C, 41.05; H, 9.64; N, 4.79. Found: 2  C, 40.77; H, 9.44; N, 4.78.  5  2  4  99  3.7.14  {Y(^-Cl)(allyI)[N(SiMe CH PMe2)2]}2-(MgCl2)x.  To a THF  2  2  solution (25 mL) of YCl[N(SiMe CH PMe ) ] (0.200 g, 0.292 mmol) was added 2  2  2  2  2  0.70 M (allyl)MgCl (0.42 mL, 0.29 mmol). After 10 minutes the THF was removed under vacuum and the resulting oil was extracted with toluene.  The clear toluene  filtrate was concentrated and cooled to -30 °C. The crystalline product of this reaction, {Y(p:-Cl)(allyl)[N(SiMe CH PMe ) ]} , is contaminated with cocrystallized MgCl ; 2  2  2  2  2  2  0.130 g of such product was isolated.  After recrystallization from toluene, this  compound gave elemental analysis consistent with an empirical formula of {Y(^-Cl)(allyl)[N(SiMe CH PMe )2]}2-(MgCl )o.7. 2  2  2  Anal. Calcd. for  2  C 6H66N P4Si Y Cl (MgCl ) .7: C, 32.58; H, 6.94; N, 2.92. Found: C, 32.68; H, 2  2  4  2  2  2  0  7.07; N, 2.86.  3.7.15 Y(aHyl) [N(SiMe CH2PMe2)2]» 13a« In a glovebox, an apparatus 2  2  designed for filtering under N was charged with Mg(allyl) (dioxane) (69 mg, 0.35 2  2  mmol) and YCl [N(SiMe CH PMe ) ] (0.156 g, 0.354 mmol). The apparatus was 2  2  2  2  2  sealed under N , removed from the glovebox, placed on a vacuum/nitrogen line and 2  THF (60 mL) was added to the solids. This mixture was allowed to stir for 1 hour before the THF was evaporated off. To the resulting oil, hexanes (30 mL) and 1,4dioxane (10 mL) was added. The solution wasfilteredto remove MgCl (dioxane) and 2  the filtrate was evaporated to dryness. The apparatus was taken into a glovebox and the filtrate residues were reextracted with hexanes, concentrated to a few mL and cooled to -30 °C. No crystals of this compound could be isolated even though the 31  P { H ) NMR spectrum showed only 1 compound to be present. *H NMR: 5 at 20 1  °C, 6.09 (2H, p, J = 11.5), 3.4 (4H, broad, H ), 2.6 (4H, broad, H ), 0.91 (12H, t, J = s  a  1.8, PMe), 0.58 (4H, t, J = 3.9, PCH Si) and 0.18 (12H, s, SiMe); in C D C D at -40 2  6  5  3  °C, 6.11 (2H, t of t, J = 8.8 & 15.4), 3.44 (4H, d, J = 8.8, H ), 2.56 (4H, d, J = 15.4, H ), s  a  0.88 (12H, broad, PMe), 0.49 (4H, broad, PCH Si) and 0.20 (12H, s, SiMe). 2  100 1  3C{ H} NMR: [HQ-H] 8 143.54 (s, Q) [d, 142.6], 67.71 (s, C ) [t, 150.0], 19.56 1  0  (t, J = 3, PCH Si) [t, 120.1], 14.65 (t, J = 3, PMe) and 6.74 (s, SiMe) [q, 117.4]. 2  31p{lH} NMR: 5 -38.3 (d, J = 80.8).  3.7.16  YCl(Ph)[N(SiMe CH2PPri )2], 14c. 2  To a rapidly stirred ethereal  2  solution (25 mL) of YCl [N(SiMe CH PPr ) ](TFTF) (0.175 g, 0.280 mmol) was i  2  2  2  2  2  added an excess of an ethereal LiCgHs (0.052 g, 0.62 mmol) solution. The mixture immediately became cloudy and after 15 minutes the solvent was removed in vacuo. The oily residue was extracted with toluene, filtered through Celite®, concentrated to about 10 mL and cooled to -30 "C. After a few weeks, a low yield of some colourless crystals were isolated. NMR data are reported in C6D5CD3. *H NMR: 8 8.23 (d, J = 6.3, Ho), 7.42, (t, J = 7.1, H ) , 7.26 (t, J = 7.2, H ) , 1.57 (4H, m, PCHMe ), 0.87 M  P  2  (4H, m, PCH Si), 0.79 (12H, d of d, J = 7.2 & 14.4, PCHMe). 0.73 (12H, d of d, J = 7.2 2  & 14.4, PCHMe), and 0.43 (12H, s, SiMe).  " C ^ H } NMR:  8 (Q was not  located), 134.81 (s, C ), 127.27, (s, Cp), 127.17, (s, C ), 23.11 (s, PC_HMe ), 19.07 Q  m  2  (broad, PCHMe), 8.63 (t, J = 6.2, PCH Si) and 6.72 (s, SiMe). 3 P{ H} NMR: 8 1  1  2  0.6 (d, J = 75.3). Anal. Calcd. for C3oH NP Si Y: C, 56.67; H , 8.56; N, 2.20. Found: 54  2  2  C, 53.36; H , 8.61; N, 2.20.  3.7.17 Y Cl (Ph)[N(SiMe2CHPPri2)(SiMe2CH2PPri )][N(SiMe2CH2PPri2)2]> 2  2  2  15c. Thermolysis of a C6D5CD3 solution of YCl(Ph)[N(SiMe CH PPri ) ] in a 2  2  2  2  sealed NMR for two weeks at 47 °C resulted in a bright yellow solution. On cooling this solution to room temperature tiny yellow crystals precipitated from solution. H J  NMR:  8 7.82(d, HQ), 7.24, (t, H ) , 7.08 (t, H ) , 2.4 to 1.5 (m, PCHMe ), 1.4 to 1.1 M  P  2  (m, PCHMe), 0.90 to 0.65 (m, PCH Si), 0.60 to 0.20 (s, SiMe). 31p{lH} NMR: 8 2  44.5 (d of d of d of d , ijy.p = 47.7, J -p = 12.4, 2 j . = 7.1, 2 j . = 7.1), 34.6 (d, J . 2  2  Y  Y  p  Y  P  Y  101  P = 39.1), 12.9 (d of d, J -p = 61.2, J - p = 7.1), 12.2 (d of d, !j -p = 63.1, J - p = l  2  Y  2  Y  Y  Y  7.1). This compound has not yet been isolated in an analytically pure form. 3.8  References  1  Manastyrskyj, S.; Maginn, R. E.; Dubeck, M. Inorg. Chem. 1963,2, 904. Day, C. S.; Day, V. W.; Ernst, R. D.; Vollmer, S. H. Organometallics, 1982,1,  2  998. Hazin, P. N.; Huffman, J. C ; Bruno, J. W. Organometallics, 1987,6, 23.  3  Booij, M.; Kiers, N. H.; Heeres, H. J.; Teuben, J. H. J. Organomet. Chem. 1989,  4  364,79.  5  Heeres, H. J.; Teuben, J. H; Rogers, R. D. / . Organomet. Chem. 1989, 364, 87. Heeres, H. J.; Meetsma, A.; Teuben, J. H. J. Chem. Soc, Chem. Commun. 1988,  6  962. 7  a) Schumann, H.; Albrecht, I.; Pickardt, J.; Hahn, E. / . Organomet. Chem. 1984, 276, C5. b) Albrecht, I.; Schumann, H. J. Organomet. Chem. 1986,310, C29.  8  van der Heijden, H; Schaverien, C. J.; Orpen, A. G. Organometallics, 1989, 8, 255.  9 1 0  Fryzuk, M. D.; Carter, A.; Westerhaus, A. Inorg. Chem. 1985, 24, 642. Huheey, J. E. Inorganic Chemistry, 3  rd  ed., Harper & Roe, New York, 1978,  670-671. 1 1  Andersen, R. A.; Wilkinson, G. Inorg. Syn. Vol XIX, Shriver, D. F. (ed.), John Wiley & Sons: Toronto, 1979, 262.  102 C H A P T E R 4: A L L Y L - D D E N E C O U P L I N G A T ZIRCONIUM AND HAFNIUM  4.1  Introduction  Carbon-carbon coupling reactions are probably the single most important transformation in synthetic organic methodology. Of particular interest are those reactions 1  which occur within the coordination sphere of a transition-metal complex as the resulting stereoselectivity of the process can often be fine-tuned by changes in the ancillary ligands of that metal centre. As described in Section 1.4, a unique allyl-diene coupling reaction at 2  hafnium was discovered where the compounds HfCl(ri -QH6)[N(SiMe2CH2PR2)2] (R = 3  4  Me, Pr'), react with allyl-MgCl to generate the transient allyl-diene species, Hf(C3H5)(C4H6)[N(SiMe2CH2PR2)2l, which are transformed into the coupled products Hf(ri :r|l-C7H )[N(SiMe2CH2PR2)2] 4  11  (Scheme 4.1).  Scheme 4.1  103  This transformation is interesting for two reasons: i) this metal-mediated coupling between a C3 and a C4 fragment does not appear to have precedent and, ii) the reaction is quite sensitive to the nature of the ancillary ligand. The length of time it takes for these two complexes to complete the transformation (at room temperature) varies considerably; the compound with methyl groups at phosphorus takes about seven days, while the derivative with isopropyl groups at phosphorus takes about one hour. Consequently, it would appear that it is relief of steric strain in the diene-allyl complex that drives the reaction. However, it is interesting to note that neither of the analogous diene-allyl complexes CpM(diene)(allyl) or Cp*M(diene)(allyl) , M = Hf, Zr, have been reported as undergoing 4  5  any C—C coupling. This chapter describes some further investigations into the nature of this reaction.  4.2  Synthesis of AUyl-Diene Coupled Complexes  The  addition of allyl-MgCl to the diene complexes,  MC1(T) -C4H6)4  [N(SiMe2CH2PR.2)2l> is summarized in equation 4.1. C H MgCI 3  5  MCI(n -C4H )[N(SiMe CH2PR2)2]  • M(TiV-C7Hii)[N(SiMe CH PR )2] [4-1]  4  6  2  2  2  2  THF M = Hf, F U P r ' purple 16c  M = Hf, R = Me purple 16a M = Zr, R = Pr' green  17c  M = Zr, R = Me brown decomposition  Interestingly, the synthesis of the zirconium derivative, 17c, takes about two hours at room temperature while the analogous zirconium derivative to 16a was not observed to form even after two weeks of stirring. The P{ H) NMR spectrum of this crude brown 31  1  mixture from this reaction was indicative of decomposition.  104 As these allyl-diene coupled molecules are chiral, the reaction with a substituted allyl Grignard reagent was of interest because it was possible that the formation of diastereomers might occur in unequal amounts. Therefore, the reaction of 1-methylallylMgCl with the diene complexes was investigated (Equation 4.2).  1-Me-allyl-MgCI ZrCI(ri -C4H )[N(SiMe2CH2PR2)2] 4  6  • ZrfoV-CeH^INfSiMegCHzPR^]  I"! 4 2  THF R = Me brown decomposition R = Pr' green 18c Once again, the less bulky zirconium derivative (methyl groups at phosphorus) reacted with the Grignard reagent to yield a product mixture that P{ *H} NMR spectroscopy indicated 31  to be decomposition. The more bulky derivative (isopropyl groups at phosphorus) reacted with this Grignard reagent to yield two products in unequal amounts (approximately 2:1 by 31  P{ H} NMR spectroscopy). There are four possible isomers which can be formed due l  to the fact that the coupling can occur at either end of the allyl moiety and the methyl group can have two orientations (Figure 4.1). Of the four isomers, X-ray crystallography showed that C and D are the two which are formed.  Figure 4.1 Four possible isomers for the coupling of 1-methylallyl with butadiene. It is interesting to note that although C and D are formed in unequal amounts, the P{ !H} 31  NMR spectrum of the crystalline product shows equal amounts of C and D.  105  4.3 Molecular structures of Hf(Ti4:nl-C7Hii)[N(SiMe2CH2PPri )2], 2  16c, and Zr(Ti4:nl-C8Hi3)[N(SiMe2CH PPri )2], 2  2  1  8  c  Both Hf(Ti4:T l-C7Hii)[N(SiMe2CH2PPr» )2], 16c, and Zr(Ti4:nl-C Hi3)2  1  8  [N(SiMe2CH2PPr2)2], 18c, have been crystallographically characterized. Tables 4.1-4.4 i  contain selected bond length and bond angle data, while Figures 4.2 and 4.3 show the structures of these compounds and the atom numbering scheme. Table 4.1: Selected Bond Angles for Zr(Ti :rj -C8Hi3)[N(SiMe2CH PPr 2)2], 18c. 4  1  i  2  Bond  Length  Bond  PI—Zr—P2  149.26 (4)  Zr—C25—C24  72.7 (3)  PI—Zr—N  76.1 (1)  C25—C24—C23  118.9 (5)  P2—Zr—N  74.6 (1)  C24—C23—C22  122.5 (6)  Length  C25—Zr—N  110.5 (2)  C23—C22—C21A  117.8 (7)  C24—Zr—N  121.5 (2)  C23—C22—C21B  147 (1)  C23—Zr—N  148.7 (2)  C22—C21A—C20A 104.0 (8)  C22—Zr—N  179.0 (2)  C22—C21B—C20B 100(2)  C19—Zr—N  111.1 (2)  C21A—C20A—C19 114.2 (9)  C22—C21A—C26  116.3 (7)  C21B—C20B—C19 114(2)  C22—C21B—C26  107 (1)  C20A—C19—Zr  120.8 (6)  C20A—C21A—C26  114.7 (8)  C20B—C19—Zr  115(1)  C20B—C21B—C26  121 (2)  C19—Zr—C25  132.2 (2)  106 Table 4.2: Selected Bond Lengths for Zr(r| :T|l-C8Hi3)[N(SiMe2CH2PPr2)2], 18c. 4  Bond  i  Length  Bond  Length  Zr—PI  2.782 (2)  C25—C24  1.437 (8)  Zr—P2  2.850 (2)  C24—C23  1.405 (8)  Zr—N  2.190 (4)  C23—C22  1.376 (9)  Zr—C25  2.345 (5)  C22—C21A  1.52 (1)  Zr—C24  2.358 (4)  C22—C21B  1.57 (2)  Zr—C23  2.500 (5)  C21A—C20A  1.51 (4)  Zr—C22  2.573 (5)  C21B—C20B  1.59 (4)  Zr—C19  2.305 (5)  C20A—C19  1.54 (2)  C26—C21A  1.44 (1)  C20B—C19  1.28 (4)  C26—C21B  1.57 (2)  Table 4.3: Selected Bond Lengths for Hf(ri :r| -C7Hii)[N(SiMe2CH2PPr 2) ], 16c. 4  1  i  2  Bond  Length (A)  Bond  Length (A)  Hf—PI  2.767 (6)  Hf—N  2.129 (13)  Hf—P2  2.812 (6)  C19—C20  1.43 (3)  Hf—C19  2.32 (2)  C20—C21  1.45 (5)  Hf—C20  2.36 (2)  C21—C22  1.36 (5)  Hf—C21  2.56 (2)  C22—C23  1.44 (4)  Hf—C22  2.58 (3)  C23—C24  1.53 (4)  Hf— C25  2.22 (3)  C24—C25  1.52 (4)  107  Table 4.4: Selected Bond Angles for Hf(Ti :ril-C7Hii)[N(SiMe2CH2PPr )2], 16c. 4  i  2  Bonds  Angle (deg)  Bonds  Angle (deg)  PI—Hf—-P2  150.3 (2)  Hf—C19—C20  73.8 (13)  PI—Hf—-N  77.8 (4)  C19—C20—C21  120 (3)  P2—Hf—-N  74.6 (4)  C20—C21—C22  118(4)  C19—Hf-- N  105.1 (7)  C21—C22—C23  122 (4)  C20—Hf-- N  118.4(9)  C22—C23—C24  107 (2)  C21—Hf-- N  148.1 (14)  C23—C24—C25  110(3)  C22—Hf-- N  174.9 (8)  C24—C25—Hf  121 (2)  C25—Hf-- N  115.9 (8)  C25—Hf—C19  135.4 (9)  The hafnium complex 16c crystallizes in the chiral space group PA\. The particular crystal which was crystallographically characterized is enantiomerically pure and the absolute configuration of the molecule is shown in Figure 4.3. The zirconium complex 18c however, crystallizes in the space group PI as a mixture of both diastereomers C and D and is not chiral (enantiomers C and D' are both present). The presence of two different molecules in one crystal complicated the solution and the structure was modeled as a 70:30 mixture (D to C) of both diastereomers. The net result is that only two atoms in the T| 5  C8H13 fragment (C20 and C21) differ in position between the two molecules, with the  "allyl-methyl carbon" actually occupying the same spatial position in both molecules.  Figure 4.2  Molecular structure of Zr(Tl4:r l-C8Hi3)[N(SiMe2CH2PPr 2)2], i  1  Two Chem 3 D ® views showing the two different diastereomers and an 01 stereoview showing the complete atom numbering scheme.  Figure 4.3 Molecular structure of Hf(Ti :Til-C7Hii)[N(SiMe2CH PPr 2)2], 16c. A 4  i  2  Chem 3D® view for comparison with 16c and an ORTEP stereoview showing the complete atom numbering scheme.  110  4.4  N M R Spectroscopic Characterization  The allyl-diene coupled products 16c-18c display temperature invariant NMR spectra that are in accord with the crystal structure. All groups of atoms are inequivalent and the NMR spectra reflect this lack of symmetry. The P{ 31  NMR spectra of the  r| :r| -C7Hii-derivatives 16c and 17c show an AB quartet with transoid Jp.p coupling 4  2  1  constants of 65 Hz and 66 Hz, respectively, while the spectrum of the zirconium complex 18c shows two AB quartets (2jp.p coupling constants of 67 and 59 Hz) for the two diastereomers (Figure 4.4). The *H NMR spectra are complex due to all the inequivalent groups of atoms but most of the resonances for 16c and 17c can be assigned. Assignment of all the proton resonances for 18c is not possible due to signal overlap: there are eight silyl-methyl (SiMe), four methylene (SiCHP) and sixteen isopropyl-methyl (PCHMe) resonances present over a two ppm range (Figure 4.5). The assignments of the resonances in the C{ H} NMR spectrum of 16c and 17c can be made, while again, the 13  l  diastereomeric mixture of 18c has too many overlapping resonances for accurate assignments to be made. The ^Cf^H} NMR spectrum of just the CgHi3 fragments are shown in Figure 4.6.  Ul !  1  i i  1  | '—' i — ' l » i—i—i—|—f—f—i—i—r~r—i—r  22  ab  !  i i—i—r—i—i—[1'iTfii  lb .  tb  i i T j r i—n rr -  r t T J I I I—r i i i T T J I — i — i — i  w  Figure 4.4: 121 MHz 3 1 p { l H ) NMR spectra in C 6 D  ife  6  i i i—r  lb  PPH  of Z r ( r i : r i l - C H i ) 4  8  3  [N(SiMe2CH2PPr 2)2], 18c. The upper spectrum is of the crude reaction mixture and i  shows the different proportions of the two diastereomers, the lower spectrum is of a 1:1 mixture of crystallized products. ZrCl(T| -C4H6)[N(SiMe2CH PPr 2)2] is marked 4  with an asterisk.  2  i  112  Figure 4.5: 300 MHz H NMR spectra of Zr(Ti4:-nl-C8Hi3)[N(SiMe CH2PPr 2)2], J  i  2  18c, in C6D . 6  113  Figure 4.6:  A portion of the 75.4  M H z ^CpH}  Zr(Ti4:Til.C8Hi3)[N(SiMe2CH2PPri2)2]. 18c.  N M R spectra i n C 6 D 6 of  114  In order to explain the formation of the two diastereomers, 18c, the mechanism in Scheme 4.2 (which is different than the one presented in section 1.4, page 15) is suggested.  Scheme 4.2 Me Si  Me Si  2  2  \  Zr<*  Me Si'  j  2  n -allyl^=^ri -allyl 3  1  Me Si 2  ^  electrocyclic rearrangement  electrocyclic rearrangement  Me Sl;  Me Si^  ^  Me Si  Me Si^  j  2  7  2  2  Pr'p  p-hydride elimination  Me Si 2  2  Me Si^  ^  2  N  Me s/  Zr^A  j  2  Me Si 2  Me Si 9  H  i  115  All of the steps in the proposed mechanism of Scheme 4.2 have precedent. The first step where the allyl moiety is undergoing an T| - to r|^transformation is reasonable as the allyl3  diene intermediate Hf(C3H5)(C4H6)[N(SiMe CH2PMe2) ] can be identified by NMR 2  2  spectroscopy as containing an allyl unit undergoing syn-anti exchange.  3  The  regioselectivity of this reaction can be explained by having the 1-methylallyl unit go rj with 1  the methyl group in the y position; this also makes intuitive sense because the reaction is sterically driven. As the methyl group can have two orientations, two different transition states are formed. The second step involves an electrocyclic six-membered ring transition state in a "chair type conformation". This type of transition state has been invoked to explain the addition of crotyltitanocenes to aldehydes. The final two steps, p-hydride 6  elimination and olefin insertion, are well founded processes in organometallic chemistry.  7  In an attempt to better understand this allyl-diene coupling transformation, the reaction of allylmagnesium chloride and ZrCl(T) -C4H6)[N(SiMe2CH2PPr 2)2] was 4  i  monitored by P{ H} NMR spectroscopy (Figure 4.7). The singlet due to the diene31  1  chloride complex disappears afterfifteenminutes, and doublet of doublet resonances (AX patterns) for three other compounds can be seen. The AX pattern at 26.1 and 17.6 ppm ( Jp.p = 50.9 Hz) can be assigned to the intermediate allyl-diene complex, and another AX 2  pattern at 20.6 and 12.1 ppm ( Jp.p = 65.6 Hz) can be identified as the T| :r| -C7Hii 2  4  1  coupled product. The other AX set of doublets at 27.4 and 11.1 ppm ( Jp.p = 34.2 Hz) is 2  presumably due to an intermediate in the reaction sequence. Of the intermediates postulated in Scheme 4.2, the diene hydride species formed after P-hydride elimination step has the appropriate symmetry for a complex with inequivalent phosphines. Attempts to detect a hydride species in the *H NMR failed, although such a signal could still be present and be buried under another resonance.  116  30  25  '  2  '  15  0  '  I"  5  P  P  M  °  Figure 4.7: 121.4 MHz 31p{lH} NMR spectra in THF/C6D of C H MgCl and 6  3  5  ZrCl(ri -C4H6)[N(SiMe2CH2PPr 2)2] after 50 mins (upper) and 120 mins (lower). 4  i  Note that the two scales are not identical.  117 4 . 5 Summary The coupling of allyl and butadiene fragments at hafnium or zirconium is a process which is very sensitive to the nature of the ancillary ligands at the metal. For the complexes, MCl(r| -C4H6)[N(SiMe2CH2PR2)2L addition of an allyl-Grignard reagent 4  results  in  formation  of  the  C — C coupling  products,  M(r| :T| 4  1  C7H1 i)[N(SiMe2CH2PR2)2]- The reaction takes about one hour when M = Hf & R = Pr , 1  two hours when M = Zr & R = Pr , a week when M = Hf & R = Me, and results only in 1  decomposition when M = Zr & R = Me. No coupling has been reported to occur for (C R5)M(C3H )(C4H6) (M = Hf, Zr; R = Me, H) compounds. 5  5  Similar results are obtained when 1-methylallylmagnesium chloride is reacted with ZrCl(rj -C4H6)[N(SiMe2CH2PR2)2]- When R = Me, decomposition occurs and when R = 4  Pr*, after two hours the coupling is complete. Two of the four possible coupled products are formed in unequal amounts, and the coupling occurs exclusively at the substituted end of the 1-methylallyl unit as determined by X-ray crystallography. Which diastereomer is formed in higher yield was not determined.  A mechanism for converting the MCl(ri -C4H6)[N(SiMe2CH2PPr 2)2] complexes to 4  i  the coupled products via two intermediate species has been suggested. Evidence for one intermediate was found. The coupling reaction can be followed by P{ H} NMR 31  1  spectroscopy and signals for the allyl-diene complex, an unknown intermediate as well as the final coupled product can be observed.  118 4.6  Experimental Procedures  4.6.1 General Procedures. The same general procedures as outlined in Section 2.7 were followed.  The diene complexes MCl(T| -C4H6)[N(SiMe2CH2PR2)2] were 4  synthesized according to the literature procedures , and the Grignard reagents were made 8  from magnesium and allylchloride or 3-chloro-l-butene in THF.  Figure 4.8 The numbering scheme used for the NMR spectroscopic assignments.  4.6.2  Hf(Ti4:Til.C7Hii)[N(SiMe2CH PMe2)2], 16a. To a red solution (20 mL) 2  of HfCl(ri -C4H6)[N(SiMe2CH2PMe2)2] (0.270 g, 0.492 mmol) 0.73 M allylmagnesium 4  chloride (0.67 mL, 0.49 mmol) in THF was added dropwise with rapid stirring. The red solution initially faded to orange and then over a period of days became a dark burgundy colour. After one week the solvent was removed under vacuum, the residue was extracted with hexanes and filtered through Celite® to remove MgCl2. H NMR: 8 6.00 (m, H5), 1  4.48 (m, H ), 3.20 (m, H ), 2.78 (m, H ) , 2.10 (m, H ), 2.10 (m, H4), 1.96 (m, 6  2a  3b  3a  H b), 1.57 (m, H ), 1.41 (m, H ), 0.41 (m, Hi ), (Hi is obscured), 1.25 (d, J . = 2  2  7b  7a  b  6, PMe), 1.17 (d, Jp-H = 6, PMe), 0.93 (d, J . 2  2  P  a  P  = 6, PMe), 0.91 (d, J . 2  H  P  H  H  = 6, PMe),  0.89 (obscured SiMe CHPMe ), 0.73 (dd, J . = 9 , J - H = 14, SiMe CHPMe ), 0.50 2  2  2  2  P  H  H  2  2  119 (dd, Jp.H = 8 J - H = 14, SiMe CHPMe ), 0.34 (dd, 2 j . 2  = 9.5 J .  2  H  2  2  P  = 14,  2  H  H  H  SiMe CHPMe ), 0.24 (s, SiMe), 0.16 (s, SiMe), 0.14 (s, SiMe), 0.07 (s, SiMe). 2  2  13C{lH} NMR: 8 126.14 (s, C ) [d, l J . 5  c  = 149], 93.42 (s, Qj) [d, 1J -H = 144],  H  C  81.82 (s, C ) [d, iJc-H = 161], 63.41 (s, Ci) [t, lJ -H = 109], 49.21 (s, C ) [t, Jc-U = l  4  C  7  141], 39.75 (s, C ) [t, iJc-H = 124], 35.71 (s, C ) [t, iJrj-H = 126], 18.35 (s, PCH Si), 2  3  2  17.20 (s, PCH Si), 15.08 (d, ijp-c = 15.2, PMe), 14.48 (d, iJp.c = 9.3, PMe), 14.12 2  (d, iJp.c = 15.4, PMe), 13.95 (d, ] .  = 9.9, PMe), 6.50 (s, SiMe), 6.12 (s, SiMe),  l  P C  6.03 (s, SiMe), 5.98 (s, SiMe). 31p{lH} NMR: 8 -8.8 (d, 2j . = 76), -16.6 (d, J . 2  P  P  P  P = 76). Thus far this compound has not been obtained in an analytically pure form.  4.6.3  Hf(r|4:nl.C7Hii)[N(SiMe CH PPr ) ],  16c. The identical procedure  i  2  2  2  2  described for 15a was used except that the reaction only requires one hour of stirring prior to workup. Red HfCl(Ti -C4H6)[N(SiMe CH PPr ) ] (0.300 g, 0.454 mmol) reacts with 4  i  2  2  2 2  0.70 M allylmagnesium chloride (0.65 mL, 0.46 mmol) to yield 0.248 g (82%) of purple product. !H NMR: 8 6.36 (m, H ), 4.98 (m, HQO, 3.13 (m, H ), 2.74 (m, H ), 2.66 5  (m, H ), 2.52 (m, 3a  H4),  2a  3b  2.44 (m, H ), 1.54 (m, H ), 1.30 (m, H ), 1.05 (m, Hi ), 2b  7b  7a  a  0.06 (Hi ), 2.30 (dsept, 2 j . = 2, J - = 7, PCHMe), 2.23 (dsept, 2 j . = 2, J - = 3  b  P  H  3  H  H  P  H  H  H  7, PCHMe), 1.96 (m, PCHMe), 1.94 (m, PCHMe), 1.27, 1.26, 1.16, 1.15, 1.08, 1.06, 1.03 & 1.10 (for all 8 resonances: dd, J . = 4 , J . = 7, PCHMe)0.98 (dd, J . = 8, 3  3  P  2  JH-H  2  H  H  H  P  H  = 14, SiMe CHPMe ), 0.84 (dd, J . = 8, J . = 14, SiMe CHPMe ), 0.57 (d, 2  2  2  2  P  H  H  H  2  2  2jp_ = 7.6, SiMe CH2PMe ), 0.32 (s, SiMe), 0.27 (s, SiMe), 0.24 (s, SiMe), 0.21 (s, H  2  2  SiMe). 13C{1H} NMR: 8 123.48 (s, C ) [d, iJrj-H = 147], 90.22 (s, C ) [d, HQ-H = 5  6  160], 88.10 (s, C ) [d, lJc-H = 148], 69.42 (s, Ci) [t, lJ -H = HO], 51.52 (s, C ) [t, 4  C  7  ^C-H = 139], 37.85 (s, C ) [t, lJ -H = 121], 34.72 (s, C ) [t, lJ -H = 127], 25.95 (d, 2  1J . P  C  3  C  = 7.7, PCHMe ), 25.48 (d, l J . = 5.2, PCHMe ), 25.18 (d, l J . = 6.4,  C  2  P  C  2  P  c  P£HMe ), 25.07 (d, Jp. = 7.8, P£HMe ), 20.25 (d, J . = 4.5, PCHMe?). 20.19 (d, l  2  2  C  2  P  C  2jp_ = 5.3, PCHMS2), 19.70 (s, PCHMe?). lv.?0 (s, PCHMe?). 19.41 (d, J . = 3.7, 2  c  P  C  120 PCHMS2), 19.34 (s, PCHM£2), 19.25 (s, PCHMS2), 19.00 (s, PCHM&2), 11.03 (d, U . P  C = 4.0, PCH Si), 8.63 (d, 1J . = 3.8, PCH Si), 6.40 (s, SiMe), 6.31 (s, SiMe), 6.11 2  P  C  2  (s, SiMe), 6.08 (s, SiMe). 3lp{lH} NMR:  6 +22.8 (d, J . = 65), +17.3 (d, 2j . = 2  P  P  P  P  65). Anal. Calcd. for C H 5HfNP Si : C, 45.06; H, 8.32; N, 2.10; Found: C, 45.09; 25  5  2  2  H, 8.50; N, 2.24.  4.6.4  Zr(ri :ri -C7Hii)[N(SiMe CH PPri ) ],17c. The identical procedure 4  1  2  2  2  2  described for 15a was used except that the reaction only requires two hours of stirring prior to workup. Dark red ZrCl(Ti -C4H )[N(SiMe2CH PPr2)2] (0.350 g, 0.610 mmol) 4  i  6  2  reacts with 0.80 M allylmagnesium chloride (0.76 mL, 0.61 mmol) to yield 0.254 g (72%) of dark green product. *H NMR:  6 6.28 (m, H ), 4.52 (m, H6), 3.18 (m, H ), 2.93 5  (m, H ), 2.75 (m, H4), 2.3 (obscured,  3a  & H ), 1.57 (m, H ), 1.50 (m, H ), 0.10  3b  2b  7b  7a  (obscured, Hi ), -0.25 (Hi ), 2.20 (m, PCHMe), 2.10 (m, PCHMe), 1.88 (m, PCHMe), a  b  I. 88 (m, PCHMe), 1.4-0.9 (8 PCHMs_), 0.55 (m, SiCH P), other SiCH P resonances 2  2  are obscured, 0.29 (s, SiMe), 0.22 (s, SiMe), 0.20 (s, SiMe), 0.15 (s, SiMe). 13c{lH} NMR:  8 124.91 (s, C ), 101.97 (s, C ), 79.28 (s, C4), 69.40 (s, Ci) 51.52 (dd, 2j _ = 5  6  p  3.1, 2 j . = 5.8, C ), 41.94 (s, C ), 34.93 (s, C ), 26.61 (d, J . 2  P  P  7  2  3  P  C  p  = 7.0, PCHMe),  25.46 (d, 2 j . = 2.7, PCHMe), 25.16 (d, J . = 4.4, P£HMe), 24.89 (d, J . = 5.8, 2  P  2  c  P  C  P  C  P£HMe), 20.45 (s, PCHMfis), 20.40 (s, PCHM&2), 20.31 (s, PCHM&2), 20.22 (s, PCHM£2), 19.67 (s, PCHM£2), 19.62 (s, PCHMe^), 19.49 (s, PCHM&2), 18.31 (s, PCHMe?). 12.33 (d, J . = 6.6, PCH Si), 9.95 (d, l J . = 5.8, PCH Si), 6.49 (d, J = l  ?  2  c  P  c  2  3.0, SiMe), 6.14 (d, J = 2.8, SiMe), 5.94 (s, SiMe ). 31p{lH} NMR: 2  2  J . P  8 +21.2 (d,  = 66), +12.5 (d, J .p = 66). Anal. Calcd. for C H Z r N P S i : C, 51.86; H, 2  P  P  25  55  2  2  9.57; N, 2.41; Found: C, 51.96; H, 9.59; N, 2.47.  4.6.5  Zr(ri :ri .C8Hi3)[N(SiMe CH PPr 2)2], 18c. 4  1  i  2  2  The identical procedure  described for 15a was used except that the reaction only requires two hours of stirring  121 prior to workup. Dark red ZrCl(Ti4-C H )[N(SiMe2CH PPr2)2]  (0.292 g, 0.509 mmol)  i  4  6  2  reacts with 0.33 M 1-methylallylmagnesium chloride (1.54 mL, 0.51 mmol) to yield 0.181 g (60%) of dark green product. These green crystals are a 1:1 rnixture of diastereomers. IH NMR: 8 6.42 (m, H ), 6.20 (m, H ), 5.20 (m, He), 4.34 (m, H6), 3.22 (m, H 4 ) , 5  5  2.68 (m), 2.54 (m), 2.47 (m), 2.22 (m), 2.12 (m), 1.91 (m), 1.64 (m), 1.50 (m), 1.46 (d, J = 6, C8-Me), 1.40 (d, J = 6, C -Me), 1.39 to 0.90 (overlapping resonances), 0.55 (d, J 8  = 7), 0.35 (s, SiMe), 0.26 (s, SiMe), 0.23 (s, SiMe), 0.22 (s, SiMe), 0.21 (s, SiMe), 0.18 (s, SiMe), 0.14 (s, SiMe), -0.54 (m, Hi), 2.20 (m, PCHMe), 2.10 (m, PCHMe), 1.88 (m, PCHMe), 1.88 (m, PCHMe), 1.4-0.9 (8 PCHMa), 0.55 (m, SiCH P), other 2  SiCH P resonances are obscured, 0.29 (s, SiMe), 0.22 (s, SiMe), 0.20 (s, SiMe), 0.15 2  (s, SiMe). 3C{ H} NMR: 8 124.42 (s, C ), 117.12 (s, C ), 108.74 (s, C ), 95.40 1  1  5  5  6  (s, C ), 94.65 (s, C ), 76.48 (s, C ), 68.00 (s, Ci) 65.18 (s, Ci) 50.04 (s, C ), 47.79 (s, 6  4  4  2  C ), 49.88 (m, C7), 49.84 (m, C7), 42.68 (s, C ), 37.87 (s, C ), 23.44 (s,C ), 22.12 2  3  3  8  (s,C ), 26.59 (d, 2 j . = 6.8, P£HMe), 26.49 (d, J . = 7.8, P£HMe), 25.72 (d, 2 j . 2  P  8  c  P  P  C  c  = 2.6, PCHMe), 25.30 (d, J . = 5.4, PCHMe), 25.11 (d, J . = 4.5, PCHMe), 24.93 2  2  P  C  P  (d, 2jp_ = 6.0, 2 PCHMe), 24.58 (d, j . 2  c  PCHMS2),  p  c  C  = 3.5, PCHMe), 20.67 to 19.49 (12  19.24 (s, PCHMe?). 19.10 (s, PCHMS2), 18.43 (s, PCHMe2), 18.27 (s,  PCHMe?). 12.46 (d, Up.c = 6.2, PCH Si), 10.82 (d, l J . = 6.5, PCH Si), 10.02 (d, 2  P  c  2  Up-c = 5.3, PCH Si), 9.35 (d, iJ^c = 5.6, PCH Si), 6.53 to 5.68 (SiMe). 31p{lH} 2  2  NMR: 8 +18.5 (d, J . = 59), +15.7 (d, J . = 59) major diastereomer, +21.4 (d, J . 2  2  P  P  2  P  P  = 67), +11.5 (d, J . = 67) minor diastereomer. Anal. Calcd. for C26H57ZrNP2Si2: 2  p  P  P  P  C, 52.65; H, 9.69; N, 2.36; Found: C, 52.66; H, 9.82; N, 2.29.  122  4.7  1  References  Yamamoto, A. Organotransition Metal Chemistry; Wiley-Interscience: Toronto, 1986,374, and references therein.  2  Stille, J. K. In Modern Synthetic Methods; Scheffold, R.; Ed.; 1984, Vol. 3, 2.  3  a) Fryzuk, M . D.; Haddad, T. S.; Rettig, S. J. Organometallics, 1988, 7, 1224. b) Haddad, T. S. M.Sc. Thesis, UBC, 1987.  4  a) Erker, G.; Berg, K.; Kruger, C ; Muller, G.; Angermund, K.; Benn, R.; Schroth, G. Angew. Chem., Int. Ed. Engl. 1984,23, 455. b) Erker, G.; Berg, K.; Benn, R.; Schroth, G. Angew. Chem., Int. Ed. Engl. 1984,23, 625.  5  Blenkers, J.; de Liefde Meijer, H. J.; Teuben, J. H.; / . Organomet. Chem. 1981, 218, 383.  6  Collins, S.; Dean, W. P; Ward, D. G. Organometallics, 1988, 7, 2289.  7  Collman, J. P.; Hegedus, L . S.; Norton, J. R.; Finke, R. G. Principles and Applications of Organotransition Metal Chemistry, University Science Books, California, 1987, 2  8  nd  ed., 380-387.  Fryzuk, M. D.; Haddad, T. S.; Rettig, S. J. Organometallics, 1989,5, 1723.  123  C H A P T E R 5:  SYNTHESIS A N D C H A R A C T E R I Z A T I O N O F A SIDE-ON DINITROGEN C O M P L E X O F ZIRCONIUM  5.1  Introduction  One of the milestones of modem inorganic chemistry was the discovery that dinitrogen (N=N) could act as a ligand. Since the original report by Allen and Senoff in 1  1965 on the preparation of [Ru(NH3)5N2] (Equation 5.1), numerous N complexes have 2+  2  been synthesized and structurally characterized.  2  RuCl (H 0) + excess H N N H ( H 0 ) 3  2  x  2  2  •  2  [Ru(NH ) (N )] 3  5  [5.1]  +2  2  By far the most prevalent mode of coordination to a metal is end-on to either one metal or end-on bridging to two metals. The first such crystallographically characterized examples ' 3  4  are shown in Figure 5.1. 2+  NH, >  H N3  •Ru-  N  H  NH  3  •N = N  H N'  Ru'  ,*  3 N==N-  NH  3  *NH Ru-  8  •NH,  H,N  H,N NH  N H  3  HQN  4+  NH,  3  3  NH  3  Figure 5.1: Representations of the first crystallographically characterized end-on mononuclear and bridging dinuclear N complexes. 2  Activation of the coordinated N is indicated by a lengthening of the N-N bond distance 2  (cf., 1.0975 A for that of free N ) . 2  5  Typical N - N bond lengths are 1.03 to 1.16 A for  mononuclear complexes and 1.12 to 1.33 A for binuclear compounds. The side-on mode  124  of N2 coordination is extremely rare and only a few polynuclear complexes which display this mode of coordination have been crystallographically characterized.  These are  6  Side-on bonded N2 has also been observed in low  summarized in Scheme 5.1. temperature matrix isolated C o N  7 2  and ThN2 and theoretical predictions have been made 23  8  which suggest that the side-on mode of binding might be the preferred coordination mode for the early transition elements.  Core geometry for the complex cluster [Ph5Ni2N NaaLi (OEt)4(OEt2)3J2. the related cluster [(PhLi) Ni N (OEt ) ] is similar. N—N: 1.35 & 1.36 A  Molecular structure of [KN Co(PMe3)3]6 N—N: 1.16 to 1.18 A  Molecular structure of (C H )(C H ),(C H )Ti N N—N: 1.301 A  Molecular structure of (Cp' Sm) N N—N: 1.088 A  2  6  6  10  8  5  5  2  5  2  4  2  2 2 2  4  2  2  2  2  125  Prior to the discovery of Allen and Senoff, the N molecule was considered to be 2  too inert to form transition metal complexes. Thefirstedition of Cotton and Wilkinson's Advanced Inorganic Chemistry states that "the only reactions of N at room temperature 9  2  are with metallic lithium to give IJ3N and with nitrogen-fixing bacteria  The fact that  the enzyme nitrogenase will reduce N to ammonia under ambient conditions demonstrates 2  that the chemical inertness of dinitrogen can be overcome. Nitrogenase is thought to contain two molybdenum sites which, acting independently of one another, carry out the six-electron transformation of N into two equivalents of N H 3 . 2  10  Consequently, much  research is devoted to developing a transition metal based catalyst which will carry out this transformation efficiently.  11  Interest in dinitrogen complexes was heightened when Chatt reported the first 12  conversion of dinitrogen to ammonia in a protic media using a molybdenum compound; the news media was soon convinced that a major scientific breakthrough had occurred  13  and some thought that inexpensive fertilizer would soon be available. The Farmers Weekly carried the story  14  as "Cheaper nitrogen by 1990" and even our local newspaper The  Province reported the story with the somewhat exaggerated title "Basic life process 15  created in UK lab". These fanciful news stories reflect the ultimate and as yet unattained goal in thisfieldof research: the synthesis of a useful catalyst that will convert dinitrogen to ammonia under mild conditions.  Consequently, a fundamental test of any new  dinitrogen complex is to see if in fact it can be induced to convert the N ligand to ammonia 2  or hydrazine.  There have only been a few reports on zirconium dinitrogen complexes. A series of papers about the Zr(II) dimer {Cp*2Zr(N )}2(^-N ) and two reports on the Zr(IJJ) 16  17  2  2  monomer Cp2Zr[CH(SiMe ) ]N have been published. Both complexes display unique 3  2  2  features. The Zr(II) dimer has been crystallographically characterized and is the first  126  complex to display both terminal and bridging end-on N2; this was also shown to be an important feature in the conversion of N2 to hydrazine. Protonation with HCl (g) yielded one equivalent of hydrazine and released two equivalents of N2 (Equation 5.2).  (Cp* ZrN ) N + 4 H C l 2  2  2  2  •  2Cp* ZrCl + 2 N + H N N H 2  2  2  2  [5.2]  2  Labelling studies revealed that the reaction with HCl proceeded viafirstprotonation of one of the terminal N2 ligands, with release of the other terminal N2 ligand. One half of the hydrazine subsequently produced came from the remaining terminal N2 and the other half from the bridging N2. Formation of Cp*2ZrCl2 and a symmetric intermediate complex Cp* Zr(N2H)2 was inferred from the data. This latter complex reacts further with 2  additional HCl, releasing N2 generating Cp*2ZrCl2 and hydrazine.  The Zr(III) monomer Cp2Zr[CH(SiMe3)2]N2, is unique in that solution spectroscopy shows that the N2 ligand is probably bound side-on to the zirconium centre. The most compelling evidence is the temperature invariant ESR spectrum of the N 2 (or 14  1 5  N ) complex, which shows the interaction of two equivalent 2  one Zr(III) nucleus.  1 4  N (or N) centres with 15  Protonation of this complex with HCl (aq) gave about 25%  conversion of N2 to H2NNH2.  There has been only one reported dinitrogen hafnium complex. {Cp*2Hf(N2)}2(ltN2) has been prepared via the Na/K alloy reduction of Cp*2Hfl2 under one atmosphere of N2. It is thought to have the same structure as its zirconium analog.  18  127  5.2  Synthesis of {ZrCl[N(SiMe CH2PPri ) ]}2(N ) 2  2  2  2  As part of an investigation into the stabilization of lower oxidation states of zirconium utilizing the amido-diphosphine ligand, it was found that phosphine complexes of zirconium(IV) can bind 1,3-butadiene under reducing conditions. Thus, reaction of ZrCl3[N(SiMe CH PPr 2) ] with Na/Hg and 1,3-butadiene generates red ZrCl(T| i  2  4  2  2  C4H6)[N(SiMe CH PPr ) ] which can also be prepared from magnesium butadiene, i  2  2  19  2  2  [MgC4H6(THF) ]n, and ZrCl3[N(SiMe CH PPr 2)2]. i  2  2  2  However, if reduction of  ZrCl3[N(SiMe2CH PPr 2)2] by Na/Hg is carried out in toluene under just N , a deep blue i  2  solution  is  2  obtained  from  which  dark  blue  crystals  of  the  formula  { Z r C l [ N ( S i M e C H P P r ) ] } ( N ) , 19c, can be isolated in moderate yield; the same i  2  2  2  2  2  2  reduction in the absence of N results only in decomposition. Addition of 1,3-butadiene to 2  the  N  2  complex  19c  does  not  ZrCl(ri -C4H6)[N(SiMe CH PPr ) ]. i  4  2  2  2  2  generate  the  butadiene  complex  Attempts to add hydrazine to the butadiene  complex resulted only in decomposition (Scheme 5.2).  The reduction of the more bulky  derivative Z r C l 3 [ N ( S i M e C H P B u ) ] with Na/Hg under N yields a green complex t  2  2  2  2  {ZrCl[N(SiMe CH PBu ) ] } (N ), 18d. t  2  2  2  2  2  2  2  Me  5.3  2  Molecular Structure of {ZrCl[N(SiMe CH PPr 2)2]}2(li-Tl :T| -N2) i  2  2  2  2  The X-ray crystal structure of {ZrCl[N(SiMe CH PPr 2) ]}2(^-'n :'ri -N2), 19c, i  2  2  2  2  2  is shown in Figure 5.2 and Scheme 5.2; bond angles and bond lengths are given in Tables 5.1 and 5.2. The anionic ligands (NI, NI', N2, N2', CI & CY) are bound tetrahedrally to each zirconium while the two metals are fused together via a bridging side-on N unit; the 2  129 two phosphine donors at each metal lie about three degrees out of the Zr2N2 plane. The most important feature of the structure is the bridging side-on bound N2 ligand that generates a completely planar, symmetric Zr2N unit in which the zirconium-nitrogen bond 2  lengths are essentially identical at 2.024 and 2.027 (4)  A, significantly  shorter than the  typical zirconium-amide bond length (Zr-Nl) of 2.175 (3) A found in the ancillary ligand. A survey of 11 structures containing these amido-diphosphine ligands coordinated to hafnium or zirconium reveals a range of 2.096-2.264  A for  the M-NR2 bond. By  comparison, a very short Z r - N bond length of 1.826 (4) A, consistent with a double bond (Zr=N), has been reported  20  for the imide derivative Cp2Zr(NBu )(THF). The N-N bond t  distance of the bridging N2 ligand in 19c is 1.548 (7) A, which is longer than that found in hydrazine (1.47 A), the prototypical N - N single bond. In fact, this is the longest N - N bond length ever measured for a transition metal dinitrogen complex. The only other planar side-on bridging dimer , (Cp*2Sm)2(^i-T| :T| -N2), has a very short N - N bond of 1.088 63  2  2  (12) A, and readily loses N2 in solution or under vacuum. There is one structure of a tetranuclear titanium N2 complex , (CifjH8)(C5H5)5(C5H4)Ti4(u.3-N2), where the N2 is 6b  terminally bound to two titaniums and side-on bound to one titanium. It has a long N - N bond distance of 1.301 A, somewhat longer than a N - N double bond (cf., azomethane at 1.24 A). The structure of the cobalt cluster [KN2Co(PMe3)3]6 has been reported , and 60  contains N2 ligands bridging end-on between potassium and cobalt centres. In addition, each dinitrogen ligand has two or three side-on interactions with other potassium atoms. The N-N bond lengths are between 1.16 and 1.18 A. There are two reported  6di6e  nickel  clusters, [(PhLi)6Ni2N2(OEt2)2l2 and [Ph Ni2N Na3Li6(OEt)4(OEt2)3]2. which display 5  2  non-planar side-on N2 bonding. These clusters have tetrahedral M2N2 cores with additional bonding interactions to four lithium atoms; the N - N bond lengths are 1.35 and 1.36 (2) A, respectively.  130  Figure 5.2: Three views of the molecular structure of 19c.  At the top are two  Chem 3D® views showing the symmetric environment about the zirconium centres. The top left view is looking down the Zr—Zr axis, while at the top right is a view showing the close contact of the isopropyl groups across the N bridge. At the bottom 2  is a stereoview of this complex showing the disorder in the ligand backbone.  131  Table 5.1: Selected Bond Angles for {ZrCl[N(SiMe CH2PPri2)2]}2(^-Tl :T|2.N2). 2  2  Bonds  Angle (deg)  Bonds  Angle (deg)  N2—Zr—N2'  44.9 (2)  NI—Zr—N2  105.2 (1)  Zr—N2—Zr'  135.1 (2)  NI—Zr—N2'  105.5 (2)  Zr—N2—N2'  67.6 (2)  NI—Zr—PI  81.9 (1)  Zr—N2'—N2  67.5 (2)  NI—Zr—P2  80.9 (1)  CI—Zr—NI  139.3 (1)  PI—Zr—P2  141.00 (5)  CI—Zr—N2  112.3 (1)  PI—Zr—N2  84.7 (1)  CI—Zr—N2*  111.9 (1)  PI—Zr—N2*  129.6 (1)  CI—Zr—PI  86.39 (5)  P2—Zr—N2  133.7 (1)  CI—Zr—P2  84.27 (5)  P2—Zr—N2*  88.8 (1)  Table 5.2: Selected Bond Lengths for {ZrCl[N(SiMe CH PPr 2)2]}2(^-ri :Ti2-N2). i  2  2  2  Bond  Length (A)  Bond  Length (A)  N2—N2'  1.548 (7)  Zr—CI  2.493 (1)  Zr—N2  2.024 (4)  Zr—PI  2.764 (1)  Zr—N2'  2.027 (4)  Zr—P2  2.772 (1)  Zr—NI  2.175 (3)  The structure of the binuclear zirconium dinitrogen complex 19c is somewhat surprising. Crystal structure determinations of other dinitrogen complexes of group 4 metals 6b.l6c.2i ( f 1  c  M  {Cp*2Zr(N )h(H-N2) and (Cp*2Ti)2(N )) show linear end-on N 2  2  2  coordination. However, Cp2Zr(R)N2 is believed to display side on bonding and there 17  132  are some theoretical predictions that a side-on structure should be more stable than a 23  linear end-on structure, particularly for the early transition elements. Given the long N-N bond length in 19c, it is reasonable to suggest that this complex consists of two Zr *" 4-  centres and a bridging N2 " unit. Even with this formalism, it is difficult to reconcile the 4  planar, symmetric structure A, particularly since this same formalism should also hold for a linear diimide structure of the type B (Scheme 5.3), a common occurrence particularly for N2 complexes of groups 5 and 6 .  Although an oversimplification, valence bond  22  arguments suggest that unsymmetrical structures similar to C might be possible if the metal is sterically and electronically unsaturated as is the case in complex 19c. That the sum of these structures results in a symmetrical, planar structure A ' (Scheme 5.3) having delocalized bonds is consistent with the relatively short Zr-N bond lengths found for the Zr2N2 core of 19c and with theoretical considerations of related bridging imide systems.  23  Scheme 5.3 N Zr  Zr  N  N  N B  A  Zr -  Zr  C  - Zr  Zr  C  133  5.4  N M R Spectra of { Z r C l [ N ( S i M e C H P R 2 ) 2 ] } 2 ( N ) 2  2  2  {ZrCl[N(SiMe CH PPr 2) ]} (N2), 19c, shows temperature invariant H and i  2  31  2  l  2  2  P{ *H} NMR spectra that are in accord with the C h symmetry of the structure. All four 2  phosphorus atoms are equivalent and give rise to a singlet at -10.0 ppm. The H NMR l  spectrum reflects the lack of symmetry on either side of the tridentate amido-diphosphine plane. Two silyl methyl, two methylene, two isopropyl methine and four isopropyl methyl resonances are observed at room temperature; the NMR spectra recorded at -80 °C are similar except that broadened signals are observed.  The NMR spectra of {ZrCl[N(SiMe2CH PBu ) ]} (N ), 19d, (containing the t  2  2  very bulky t-butyl group at phosphorus) are different.  2  2  2  For this complex variable  temperature NMR spectra are observed. At +60 "C the H NMR spectra show the same l  symmetry as the isopropyl derivative 19c. However, the two t-butyl and two silyl methyl resonances coalesce into four t-butyl and four silyl methyl resonances at 20 °C (Figure 5.3). This temperature-induced asymmetry manifests itself in the P{ ^H) NMR spectra 31  as the collapse of a singlet at 25 °C into an AB quartet (showing a trans- Jp.p of 75 Hz) at 2  0 °C (Figure 5.4). In the low-temperature limit, PI and P2 are no longer related by a mirror plane. The fluxional process can be explained by invoking rupture of the mirror plane which contains the Zr, CI and amide-N atoms (Figure 5.2). Inspection of the crystal structure of 19c reveals that the isopropyl groups have oriented themselves such that four of the eight isopropyl methines are directed toward each other (Figure 5.2, top right). Replacement of the methine proton with a methyl group (i.e., transforming an isopropyl group to a t-butyl group, 19c to 19d) would lead to severe inter-ligand repulsion. Such repulsion could force a rearrangement of the four phosphorus donors and lead to the observed lowering of the symmetry in 19d.  134  Figure 5.3: 300 MHz *H NMR spectra of (ZrCltNCSiMe^H^Bu^hlhCN?.) in C6D5CD3.  The upper trace at + 60 °C and the lower spectrum was recorded at 20 °C.  135  Figure 5.4: 121 M H z 3 1 p { l H ) NMR spectra of {ZrCl[N(SiMe CH PBu 2)2]}2(N2) t  2  2  in Q D 5 C D 3 . The upper trace at + 25 "C and the lower spectrum was recorded at 0 "C.  136  5.5  Reactivity of {ZrCl[N(SiMe CH PPr 2)2]}2(N2) i  2  2  {ZrCl[N(SiMe CH PPr ) ]} (N ), 19c, is only poorly soluble in hydrocarbon i  2  2  2  2  2  2  solvents. In an attempt to collect C{ H} NMR data on 19c, it was dissolved in CDCI3, 13  :  in which it is very soluble. However, after a few seconds a reaction took place as indicated by the blue solution turning green and then orange, with formation of a white precipitate. A similar result was obtained with CD C1 , except that the reaction took about 1 minute to 2  2  complete. In both cases, the orange solution showed similar, but not identical NMR resonances (Figure 5.5). The NMR spectra were highly symmetric, similar to that obtained for ZrCl3[N(SiMe CH PPr ) ]. The P{ H} NMR spectra show only a singlet about i  2  2  2  31  1  2  two ppm upfield from where ZrCl3[N(SiMe CH PPr ) ] resonates. The *H NMR spectra i  2  2  2 2  show one silyl methyl, one methylene, one isopropyl methine and two isopropyl methyl resonances, again somewhat shifted from where ZrCl3[N(SiMe CH PPr ) ] resonates. i  2  2  2 2  Attempts to isolate these new complexes by crystallization from toluene resulted only in decomposition. A possible explanation for this reaction is that the halogen solvent is acting as an acid, cleaving the Zr—N bond with formation of cLj-hydrazine and either ZrCl(CCl3) [N(SiMe CH PPr ) ] i  2  2  2  2  2  (in the CDCI3  reaction)  or  ZrCl(CDCl ) [N(SiMe CH PPr ) ] (for the CD C1 reaction). Although it is not certain i  2  2  2  2  2  2  2  2  that this is the reaction taking place, it is known that ZrCl3[N(SiMe CH PPr ) ] is stable i  2  2  2 2  in the CDCI3 used; the P{ H} NMR spectrum of ZrCl3[N(SiMe CH PPr ) ] recorded 31  1  i  2  2  2 2  after 1 week in CDCI3 did not show any decomposition. Therefore, it is assumed that the observed reaction is not due to a trace impurity that could be present in the CDCI3, but is in fact a genuine reaction with the halogenated solvent.  137  Figure 5.5: 121 MHz 31p{lH) (upper trace) and 300 MHz *H NMR (lower trace) spectra of the crude reaction mixture from {ZrCl[N(SiMe2CH2PPr 2)2] h(N2) + i  CDCI3.  138  In  order  to  ascertain  the  degree  of  N2  activation  in  {ZrCl[N(SiMe2CH2PPr 2)2])2(N2), 18c, its reactivity with excess HCl has been i  investigated. Upon addition of excess HCl (g) the dinitrogen compound was completely decomposed with conversion of the N2 ligand to hydrazine (equation 5.3). excess HCl {ZrCl[N(SiMe CH PPr ) ]}(N )  •decomposition + H N N H  i  2  2  2  2  2  2  2  [5.3]  This process has been quantified (Table 5.3) and the conversion was measured to be 97% (an average of three trials). The possible interference on the hydrazine test from the zirconium metal or the ancillary ligands was probed by decomposing a sample of ZrCl3[N(SiMe2CH2PPr 2)2]- No hydrazine formation was detected in this reaction. i  Table 5.3: Theoretical and Calculated Hydrazine Concentrations From Reaction 5.3. Trial 18c(mg) Theoretical  %T  [Hydrazine]  Found  [Found]  [Hydrazine]  [Theoretical]  1  10  3.0 x 10-6 M  61.5  2.94 x 10-6 M  0.98  2  12.5  3.7 xl0"6M  54.5  3.70xlO- M  0.99  3  21  6.3 x IO' M  40.0  5.94 x 10"6 M  0.94  5  6  6  That the conversion of the N2 ligand into hydrazine was essentially quantitative supports the claim this moiety is best described as a N2 - ligand. If a method can be found 4  whereby the HCl decomposition can be controlled, then along with the conversion of N to 2  hydrazine it might be possible to recycle 18c into ZrCl3[N(SiMe2CH2PPr 2)2]- The i  reducing agent provides the 4 electrons and the HCl provides the four H and four Cl" +  atoms necessary for the full cycle.  139  5.6  Experimental Procedures  5.6.1  General Experimental Procedures The same general procedures as outlined  in section 2.8.1 were followed.  5.6.2  ZrCl3[N(SiMe2CH PPr 2)2]  { Z r C U N C S i M e i C l h P P r ^ h l h C N i ) , 18c.  i  2  (0.680 g, 1.15 mmol) in toluene (60 mL) was added to a 0.1 % Na/Hg amalgam (0.106 g, 4.60 mmol). The flask was then cooled to -196 °C, filled with N2, sealed and allowed to warm slowly to room temperature with stirring. The colourless solution slowly takes on the deep blue colour of the product. After two days of stirring, the N was removed and 2  the flask taken into a glovebox for product isolation. The Hg slurry was extracted several times with toluene (150 mL in total, until no more blue colour appeared in the slurry) and filtered through a column of Celite®. The Celite® from the column was then placed in a 50 mL flask, extracted severaltimeswith toluene (200 mL in total, until no more blue colour appeared in the Celite® toluene mixture) and filtered through Celite®. The toluene filtrate was then concentrated and cooled to -30° C. Several lots of crystals were collected (until the filtrate was no longer blue) to yield 0.270 g of product (44% conversion). The filtrate was then evaporated to dryness and 0.084 g of unreacted ZrCl3[N(SiMe2CH2PPr 2)2] was i  precipitated by addition of hexanes (12% unconverted starting material). *H NMR (8, 500 MHz, C6D ): 2.41 (d of sept) 3j _ = 7.3, J .  = 4.2, PCHMe ; 2.15 (d of sept)  2  6  H  H  P  H  2  3j -H = 7.2, J p . = 4.1, PCHMe ; 1.43 (d of d) 3 j . = 7.3, J . 2  3  H  H  2  1.33 (d of d) 3J -H = 7.2, 3 j . H  P  H  H  P  H  = 14.0, PCHMe?:  = 13.3, PCHMS2; 1.29 (d of d) 3 j .  H  H  H  = 7.3, 3 j . = P  H  12.2, PCHMe?: 1.27 (d of d) 3 j . = 7.2,3j . = 13.2, PCHMe?: 1.07 (d of d) J - H = 2  H  H  P  H  H  13.9, J p . = 7.0, PCH2S1; 1.00 (d of d) J - H = 13.9, J . 2  2  H  = 7.0, PCH^Si; 0.38 (s)  2  H  P  H  SiMe; 0.33 (s) SiMe. 31p{lH} NMR (8, 121.4 MHz, C D ) : +10.0 (s). Visible 6  spectrum: (Pentane, 1 cm quartz cell): "k  6  = 580 nm, e = 3500 L mol cm . Anal. -1  m&x  -1  140 Calcd. for Zr C36H88Cl2N P4Si4: C, 40.54; H, 8.31; N, 5.25. Found: C, 40.65; H, 2  4  8.48; N, 5.20.  5.6.3  {ZrCl[N(SiMe2CH PBu 2)2]}2(N2), 18d. The same procedure as for the t  2  above compound resulted in only a trace yield of product The best results came from stirring two equivalents  of sodium sand (12  mg, 0.52  mmol) with  ZrCl3[N(SiMe CH PBu 2)2] (0.161 mg, 0.249 mmol) under one atmosphere of N in t  2  2  2  toluene (60 mL) for two weeks. The yield of product (66 mg, 0.053 mmol) was 42%. *H NMR (8, 300 MHz, C D ): at 60 °C 8 1.52 (br-s, 2 PBu»), 1.29 (br-m, 2 PBu*), 1.09 7  8  (d of d, J = 12 & 2, PCH Si), 0.43 (s, SiMe), 0.28 (s, SiMe). at 20 °C 8 1.59 (t, J . = 2  P  H  6.3, PBu ), 1.47 (t, Jp. = 6.0, PBu ), 1.29 (m, 2 PBu ), 1.1-0.8 (m, 4 PCH Si), 0.47 (s, 1  1  1  H  2  SiMe), 0.44 (s, SiMe), 0.32 (s, SiMe), and 0.29 (s, SiMe). 31p{lH} NMR (8, 121.4 MHz C D ) at 20 C: +35.7 at -30° C: +35.1, +34.8 (AB quartet, J . = 75.2 ). C  7  2  8  P  P  Anal. Calcd. for Zr C44Hio4Cl N4P4Si4: C, 44.83; H, 8.89; N, 4.75; CI, 6.01. Found: 2  2  C, 45.10; H, 9.10; N, 4.87; CI, 5.90.  5.6.4 Hydrazine Analysis Hydrazine was analyzed colourimetrically according to the method of Watt and Chrisp.  In a glovebox three samples of 18c,  24  {ZrCl[N(SiMe CH PPri2) ]) (N ), (10, 12. & 21 mg each in 10 mL of toluene), were 2  2  2  2  2  5  loaded into Schlenk tubes, sealed under N , removed from the glovebox and attached to a 2  vacuum line. The nitrogen was removed and replaced with anhydrous HCl, resulting in an instantaneous loss of blue colour and formation of a white precipitate. The toluene solutions were extracted with distilled water and filtered into 250 mL volumetric flasks; 2 mL aliquots of the 250 mL solutions were added to 10 mL aliquots of a colour developer (p-dimethylaminobenzaldehyde, 4.0 g; ethanol, 200 mL; concentrated HCl, 20 mL) and diluted to 25 mL with IM HCl. After 10 minutes, percent transmittance readings were taken. The spectrometer was set to 100% transmittance using a blank solution consisting  141 of 10 mL of colour developer diluted to 25 mL with IM. HCl. Percent transmittance readings were converted to hydrazine concentrations using equation 5.4 (this equation was determined earlier from solutions of known hydrazine concentration). The results are 24  tabulated in Table 5.3.  log[hydrazine] = -6.0780 + (1.4193 x 10-)(100 - % transmittance) 2  [5.4]  A 24 mg sample of ZrCl3[N(SiMe2CH2PPr2)2] was treated in a similar manner i  and it was found to give 100% transmittance. Therefore, there is no interference with this hydrazine test from the zirconium or the other ancillary ligands.  5.7  References  1  Allen, A. D.; Senoff, C. V. J. Chem. Soc, Chem Commun. 1965, 621.  2  a) Pelikan, P.; Boca, R. Coord. Chem. Rev. 1984,55, 55. b) Henderson, R. A.; Leigh, G. J.; Pickett, C. J. Adv. Inorg. Chem. Radiochem. 1983, 27, 197. c) Dilworth, J. R.; Richards, R. L. in Comprehensive Organometallic Chemistry; Wilkinson, G.; Stone, F. G. A.; Abel, E. W. (eds.); Pergamon: Oxford, England, 1982, 8, Chapter 60, 1073. d) Chatt, J.; Dilworth, J. R.; Richards, R. L. Chem. Rev. 1978, 78, 589.  3  Bottomley, F.; Nyburg, S. C. / . Chem. Soc, Chem Commun 1966, 897.  4  Treitel, I. M.; Flood, M. T.; Marsh, R. E.; Gray, H. B. / . Am.. Chem. Soc. 1969, 91, 6512.  5  "Tables of Interatomic Distances and Configurations in Molecules and Ions", Chemical Society Special Publications;  Sutton, L. E., (ed.); The Chemical Society:  London, 1958, Vol 11. 6  a) Evans, W. J.; Ulibarri, T. A.; Ziller, J. W. J. Am. Chem. Soc. 1988,110, 6877. b) Pez, G. P.; Apgar, P.; Crissey, R. K. J. Am. Chem. Soc. 1982,104, 482. c) Hammer, R.; Klein, H.; Friedrich, P.; Huttner, G. Angew. Chem., Int.  142  Ed. Engl. 1977,16, 485. d) Jonas, K.; Brauer, D. J.; Kruger, C ; Roberts, P. J.; Tsay, Y.-H. / . Am. Chem. Soc. 1976, 98, 74.  e) Kruger, C ; Tsay, Y.-H.  Angew. Chem., Int. Ed. Engl. 1973,12, 998. 7  Ozin, G. A.; Voet, A. V. Can. J. Chem. 1973, J i , 638.  8  Green, D. W.; Reedy, G. T. / . Mol. Spectrosc. 1979, 74, 423.  9  Cotton, F. A.; Wilkinson, G. Advanced Inorganic Chemistry, 1 Ed., John Wiley st  & Sons: Great Britain, 1962, 245. 1 0  Eady, R. R.; Postgate, J.R. Nature, 1974,249, 805.  1 1  Chatt, J. / . Organomet. Chem. 1975,100, 17.  1 2  a) Chatt, J. Nature, 1975,253, 39. b) Chatt J. / . Organometal. Chem., 1975, 100, 17.  1 3  Huheey, J. E. Inorganic Chemistry, 3  rd  ed., Harper and Roe: New York, 1983,  892. 14  Farmers Weekly, Jan 10,1975.  15  The Province, Vancouver, British Columbia, Jan. 15,1975.  1 6  a) Manriquez, J. M.; Bercaw, J. E. / . Am. Chem. Soc, 1974, 96, 6229. b) Manriquez, J. M . ; Sanner, R. D.; Marsh, R. E.; Bercaw, J. E. / . Am. Chem. Soc, 1976, 98, 3042. c) Sanner, R. D.; Manriquez, J. M.; Marsh, R. E.; D. R.; Rosenberg, E.; Shiller, A. M.; Williamson, K. L.; Bercaw, J. E. / . Am. Chem. Soc, 1978, 98, 3078.  1 7  a) Gynane, M . J. S.; Jeffery, J.; Lappert, M. F. / . Chem. Soc, Chem. Commun. 1978, 34.  b) Jeffery, J.; Lappert, M . F.; Riley, P. I. / . Organomet. Chem.  1979, 181, 25. 1 8  Roddick, D. M.; Fryzuk, M . D.; Seidler, P. F.; Hillhouse, G. L; Bercaw, J. E. Organometallics, 1985,1, 97.  19  Fryzuk, M. D.; Haddad, T. S.; Rettig, S. J. Organometallics, 1989,5, 1723.  143  20  Walsh, P. J.; Hollander, F. J.; Bergman, R. G. / . Am. Chem. Soc. 1988,110, 8729.  21  Sanner, R. D.; Duggan, M.; McKenzie, T. C ; Marsh, R. E.; Bercaw, J. E. / . Am. Chem. Soc. 1976, 98, 8358.  22  (a) O'Regan, M. B.; Liu, A. H.; Finch, W. C ; Schrock, R. R.; Davis, W. M. / . Am. Chem. Soc. 1990,112, 4331. (b) Schrock, R. R.; Kolodziej, R. M.; Liu, A.  H.; Davis, A. M.; Vale, M. G. / . Am. Chem. Soc. 1990,112, 4338. 23  Thorn, D. L.; Nugent, W. A.; Harlow, R. L. / . Am. Chem. Soc. 1981,103, 357.  24  Watt, G. W.; Chrisp, J. D. Anal. Chem., 1952,24, 2006.  144  THESIS SUMMARY AND FUTURE PROSPECTS  The synthesis of a variety of new lanthanoid phosphine complexes has been achieved by complexing either one or two amido-diphosphine ligands to yttrium, lutetium and lanthanum. The bis(ligand) compounds, MCl[N(SiMe2CH2PR2)2l2> appear to be sterically saturated seven-coordinate monomers; none of these complexes show any tendency to coordinate THF, indicating that the metal coordination sphere is more saturated than a bis (cyclopentadienyl) lanthanoid complex, C p 2 L n C l . However, the amido-diphosphine complex with the largest cation and the least-basic ligand, LaCl[N(SiMe2CH2PPh2)2]2> seem to display a monomerdimer equilibrium, indicating that for lanthanum, eight coordination is at least a possibility. All of the bis(ligand) compounds are fluxional and display NMR spectra indicative of complexes where the phosphorus donors are rapidly exchanging, probably via a dissociation-reassociation pathway.  As the ligands are anchored to the host  metal via the amide donor, the phosphines cannot be lost to the bulk solvent. Although these phosphines are coming on and off the metal, it may be that the chelate effect is too strong, and that the complexation of two amido-diphosphine ligands shuts down the chemistry one might expect to be associated with these strong Lewis acids.  Of all the thermally unstable hydrocarbyl complexes that were synthesized, the only one for which it may be possible to study the reactivity of the lanthanoid-carbon bond is the lutetium-phenyl complex, Lu(Ph)[N(SiMe2CH2PMe2)2]2-  However, the  inevitable formation of the cyclometallated bis(ligand) complex will be problematic. Of all the cyclometallated complexes, the least sterically crowded one (and therefore the i  1  most reactive) should be the lanthanum derivative, La[N(SiMe CHPMe2)(SiMe CH22  PMe2)][N(SiMe2CH2PMe2)2l-  2  However, it should be noted, that this compound  145 does  not  react  with  propylene  and  is  far  less  reactive  than  any  bis(cyclopentadienyl)lanthanoid-alkyl complex. It would be fortunate if the stabilizing effect of two of these ligands on one metal could be used to generate new and unusual complexes (e.g., low valent Ln(II) compounds). Preliminary attempts to synthesize the unprecedented Y(II) complex, Y[N(SiMe2CH2PMe2)2l2> via the reduction of the Y(III) chloride, YCl[N(SiMe2CH2PMe2)2]2, with various sodium based reducing agents gave intensely-blue solutions from which the ubiquitous cyclometallated complex was isolated.  While the bis(ligand) chemistry appears to always lead to the cyclometallated complexes, compounds with just one amido-diphosphine ligand show much more promise. A variety of these complexes, M C l 2 [ N ( S i M e 2 C H 2 P R 2 ) 2 l , (R = Me, Ph, Pr , J  Bu ), were synthesized and just these simple compounds showed a varied chemistry. l  The  derivatives with methyl substituents  at phosphorus are too sterically  unsaturated, and consequently, are obtained as insoluble polymeric powders. They will dissolve in THF, but most attempts at alkylation led to decomposition; once again the cyclometallated bis(ligand) complex was identified as the major product. A route to a mono(ligand) allyl complex, {Y(allyl)[N(SiMe2CH2PMe2)2l }2(M--C1)2,  w  a  s  found, and it may be that by derivatizing this compound with a bulky alkoxide, a reactive monomeric yttrium-allyl complex, Y(OR)(allyl)[N(SiMe2CH2PMe2)2] can be obtained.  The other three mono(ligand) yttrium complexes YCl2[N(SiMe2CH2PR2)2l> (R = Ph, Pr\ BU ) are hydrocarbon-soluble and can all be obtained as THF adducts. 1  The derivative with isopropyl substituents at phosphorus was also obtained as a THF-free dimer, indicating that the metal is not sterically saturated. {YCl [N(SiMe2CH2PPr 2)2]}2, h 2  i  a s  This dimer,  good solubility properties and it should be  146  possible to generate some stable hydrocarbyl derivatives.  Related mono(ligand)  derivatives of the trivalent metals Yb, Sm, Eu should be accessible using the strategies developed in this thesis. With the added flexibility of the divalent state available for these elements (e.g., {LnX[N(SiMe2CH2PPr 2)2])n) the potential exists i  for a rich and varied chemistry.  The group 4 chemistry in this thesis was developed from the simple concept that the amido-diphosphine ligand should be capable of stabilizing the lower oxidation states of these metals.  In fact, for the diene complexes, M R ( r j - C 4 H 6 ) 4  [N(SiMe CH2PR2)2L the M(II) resonance structure is a better description than the 2  M(IV) metallacyclopentene resonance form.  The reaction where where allyl and  butadiene fragments are coupled together to generate a coordinated [rj :r| 4  1  C H 2 = C H C H = C H C H 2 C H 2 C H 2 ] " fragment can also be explained in terms of an 1  electrocyclic rearrangement at a M(II) centre. This reaction is both regioselective and partially diastereoselective when 1-methylallyl and butadiene units are coupled, as two of the four possible coupled products are formed in unequal amounts; the coupling occurs exclusively at the substituted end of the 1-methylallyl unit (as determined by X-ray crystallography) and one diastereomer is formed in higher yield than the other. The selectivity demonstrated by this coupling warrants further investigation. It would be interesting to see how general this reaction is by varying both the diene and the allyl substituents.  Another variation would be to synthesize a chiral amido-  diphosphine ligand to see if this reaction could also be made enantioselective.  As  diene rotation interconverts enantiomers, it is possible that an enantioselective coupling could occur whereby only one enantiomer would be formed. Finally, it might be possible to do a complete kinetic study on the coupling reaction as the transformation from the allyl-diene complex to the final coupled product (via an unknown intermediate) can be followed by P { H } NMR spectroscopy. 3 1  1  147  As a continuation of the investigation into low oxidation state zirconium complexes, the trichlorides, ZrCl3[N(SiMe2CH2PR.2)2] (R = Pr or Bu ), were reduced 5  l  with sodium. Dimeric dinitrogen complexes, {ZrCl[N(SiMe2CH2PR2)2l}(M-- l : l r  2  r  2  N2), were isolated, and are best formulated as containing Zr(IV) centres. It would appear that the side-on binding of the N ligand favors electron transfer to form a N 2 2  hydrazido ligand.  4 _  As these complexes have a chloride ligand available for  substitution, it would be interesting to find out what effect the introduction of a hydride, alkyl or cyclopentadienyl ligand will have on the structure and chemistry of these compounds.  The chemistry associated with this unique hydrazido (4~) ligand should be further investigated, in particular, the reaction with methylenechloride and chloroform (or other alkylhalides). It would also be interesting to find a way of recycling the dinitrogen complex back into ZrCl3[N(SiMe2CH2PR2)2L along with the release of hydrazine.  Further investigations into the chemistry of low-valent zirconium  compounds may also prove interesting; the synthesis of a phosphine complex such as Z r C l ( P R 3 ) 2 [ N ( S i M e 2 C H 2 P R 2 ) 2 l may be a way of stabilizing a very reactive Zr(II) species.  The results from this thesis demonstrate that the strategy of using an amidodiphosphine ligand to generate phosphine complexes of the early metals is successful. In addition, these phosphine complexes display reactivity patterns different from those observed for the analogous complexes incorporating cyclopentadienyl ligands. From the observed chemistry, it appears that the amido-diphosphine ligands are better able to coordinatively saturate these metals than a Cp or Cp* ligand.  148  APPENDIX  A -1  X r a y Crystallographic Analysis of r Y[N(SiMe CHPMe )(SiMe CH PMe )][N(SiMe CH PMe ) ] 2  2  2  2  2  2  2  2  2  149  Empirical  C(20)H(55)N(2)P(4)Si(4)Y(l)  Formula  Formula  Weight  648.81  Crystal  System  Monoclinic  Lattice  Parameters:  a b c beta V -  Space Z  Group  P21/c  value  18.115 ( 1 ) 15.875 ( 8 ) 12.706 ( 2 ) 92.619 3650 ( 2 )  angstroms angstroms angstroms (7) degrees  angstroms**3  (#14)  4  Dcalc  1.18  F000  1376  mu(Cu K - a l p h a )  53.58 c m * * - l  DiffTactometer  R i g a k u AFC6  Radiation  Cu K - a l p h a (lambda= 1.54178) G r a p h i te-monochromated  Temperature  21 d e g r e e s C e n t .  2-theta(max)  155.3  No.  Observations  No.  Variables  Residuals: Goodness  (I>3 . 0 0 ( s i g ( I ) ) )  Rw  3270  0.063; 0.073  of F i t I n d i c a t o r  L a r g e s t Peak  degrees  281  R;  Maximum S h i f t  g/cm**3  i n Final  2.16  Cycle  i n Final Diff.  0.10  Map  1.42  e/angstrom**3  150  Positional parameters and B(eq) atom  X  y  z  B(eq)  Y(l)  0.25215(4)  0 .51693(6)  0 .22160(7)  4.27(4)  P(D  0.3611(1)  0 .3742(2)  0.2363(2)  4.9(1)  P(2)  0.1913(2)  0 .6800(2)  0 .2297(3)  6.0(2)  P(3)  0.2156(1)  0 .4535(2)  0 .0119(2)  4.7(1)  P(4)  0.2449(2)  0 .5025(2)  0 .4487(2)  6.2(2)  Si(l')  0.4476(1)  0 .5377(2)  0 .2740(2)  4.8(1)  Si(2)  0.3510(1)  0 .6610(2)  0 .1454(2)  4.8(1)  Si(3)  0.1256(1)  0 .3467(2)  0 .1621(2)  4.6(1)  Si(4)  0.0940(2)  0 .4540(2)  0 .3451(2)  5.3(2)  N(l)  0.3672(4)  0.5710(5)  0 .2184(6)  4.2(4)  N(2)  0.1467(4)  0 .4286(5)  0 .2431(6)  4.3(4)  C(l)  0.4319(5)  0 .4251(7)  0.3178(8)  5.6(6)  C(2)  0.2496(5)  0 .6659(7)  0 .1270(8)  5.8(6)  C(3)  0.1858(5)  0 .3484(6)  0 .0430(8)  5.3(5)  C(4)  0.1466(6)  0 .5180(8)  0 .4462(9)  6.9(7)  C(5)  0.4082(6)  0 .3532(8)  0 .116(1)  7.6(7)  C(6)  0.3552(6)  0 .2684(8)  0 .292(1 )  8.8(8)  C(7)  0.1013(6)  0 .702(1)  0 .167(1)  10(1)  C(8)  0.2080(8)  0 .782(1)  0.301(1)  11(1)  C(9)  0.1323(7)  0.5027(8)  -0 . 0 4 3 ( 1 )  8.2(8)  C(10)  0.2696(7)  0 .4429(9)  -0 . 1 0 4 8 ( 9 )  7.5(7)  C(ll)  0.2854(8)  0 .576(1)  0 .546(1)  12(1)  C(12)  0.2577(7)  0 .404(1)  0 .517(1)  10(1)  C(13)  0.5267(6)  0 .5379(9)  0 .184(1)  8.5(8)  151 Positional atom  p a r a m e t e r s and B ( e q ) X  y  z  B(eq)  C(14)  0 .4802(6)  0.5987(8)  0 .393(1)  7.8(8)  C(15)  0 .3983(6)  0 .7542(7)  0 .205(1)  7.5(7)  C(16)  0 .3870(7)  0 .6545(9)  0 .009(1)  8.1(8)  C(17)  0 .1426(6)  0.2408(7)  0 .2242(9)  6.4(6)  C(18)  0 .0273(5)  0 .3452(8)  0 .1103(9)  6.5(7)  C(19)  0 .0096(6)  0 .517(1)  0 .306(1)  9.0(8)  C(20)  0 .0583(6)  0 .3599(9)  0 .418(1)  8.1(8)  152 Intramolecular  Distances  atom  atom  distance  atom  atom  distance  Y(l)  N(l)  2 .256(7)  P(4)  C(ll)  1 .83(1)  Y(l)  N(2)  2 .396(7)  Sid)  Nd)  1 .675(7)  Yd)  C(2)  2 .65(1)  Sid)  C(14)  1 .87(1)  Yd)  P(2)  2 .817(3)  Sid)  C(13)  1 .88(1)  Yd)  P(3)  2 .896(3)  Sid)  C(l)  1 .90(1)  Yd)  P(4)  2 .903(3)  Si(2)  N(l)  1 .721(8)  Y(l)  Pd)  3 .005(3)  Si(2)  C(2)  1 .84(1)  Pd)  Cd)  1 .80(1)  Si(2)  C(15)  1 .86(1)  Pd)  C(5)  1 .82(1)  Si(2)  C(16)  1 .88(1)  Pd)  C(6)  1 .83(1)  Si(3)  N(2)  1 .690(8)  P(2)  C(2)  1 .73(1)  Si(3)  C(18)  1 .87(1)  P(2)  C(7)  1 .81(1)  Si(3)  C(17)  1 .88(1)  P(2)  C(8)  1 .86(2)  Si(3)  C(3)  1 .91(1)  P(3)  C(3)  1 .80(1)  Si(4)  N(2)  1 .692(7)  P(3)  C(9)  1 .81(1)  Si(4)  C(4)  1 .86(1)  P(3)  C(10)  1 .82(1)  Si(4)  C(19)  1 .88(1)  P(4)  C(4)  1 .80(1)  Si(4)  C(20)  1 .89(1)  P(4)  C(12)  1 .80(2)  153 I n t r a m o l e c u l a r Bond Angles atom  atom  atom  angle  atom  atom  atom  N(l)  Y(l)  N(2)  165.2(3)  C(6)  Pd)  Y(l)  131.9(4)  N(l)  Yd)  C(2)  69.5(3)  C(2)  P(2)  C(7)  105.2(6)  N(l)  Yd)  P(2)  90.9(2)  C(2)  P(2)  C(8)  112.6(6)  N(l)  Yd)  P(3)  106.7(2)  C(2)  P(2)  Yd)  66.5(4)  N(l)  Yd)  P(4)  97.6(2)  C(7)  P(2)  C(8)  99.6(7)  N(l)  Yd)  Pd)  71.5(2)  C(7)  P(2)  Yd)  120.5(5)  N(2)  Y(l)  C(2)  125.2(3)  C(8)  P(2)  Y(l)  139.2(5)  N(2)  Yd)  P(2)  102.6(2)  C(3)  P(3)  C(9)  103.3(5)  N(2)  Yd)  P(3)  75.6(2)  C(3)  P(3)  C(10)  105.6(6)  N( 2 )  Y(l)  P(4)  76.6(2)  C(3)  P(3)  Yd)  100.3(3)  N(2)  Yd)  Pd)  94.4(2)  C(9)  P(3)  C(10)  101.4(6)  C(2)  Yd)  P(2)  36.7(2)  C(9)  P(3)  Yd)  110.8(5)  C(2)  Yd)  P(3)  83.9(2)  CdO)  P(3)  Yd)  132.3(4)  C(2)  Yd)  P( 4 )  121.3(2)  C(4)  P( 4 )  C(12)  103.5(6)  C(2)  Yd)  Pd)  134.3(2)  C(4)  P( 4 )  C(ll)  106.9(6)  P(2)  Yd)  P(3)  106.2(1)  C(4)  P( 4 )  Yd)  93.5(4)  P(2)  Yd)  P(4)  90.0(1)  C(12)  P( 4 )  C(ll)  101.0(8)  P(2)  Y(l)  Pd)  161.38(9)  C(12)  P( 4 )  Yd)  122.4(5)  P(3)  Y(l)  P(4)  150.2(1)  Cdl)  P(4)  Y(l)  126.0(5)  P(3)  Yd)  Pd)  65.24(8)  N(l)  Si(l)  C(14)  114.5(5)  P(4)  Yd)  Pd)  86.5(1)  N(l)  Sid)  C(13)  114.5(5)  C(l)  Pd)  C(5)  102.5(5)  N(l)  Si(l)  C(l)  106.4(4)  C(l)  Pd)  C(6)  104.2(6)  C(14)  Si(l)  C(13)  105.8(6)  C(l)  Pd)  Yd)  98.4(4)  C(14)  Sid)  C(l)  107.2(5)  C(  Pd)  C(6)  101.2(6)  C(13)  Si(l)  C(l)  108.1(5)  Pd)  Yd)  114.7(4)  N(l)  Si(2)  C(2)  104.4(4)  5)  C(5)  angle  154 atom  atom  atom  atom  atom  atom  angle  N(l)  £i(2)  C(15)  112 .2(4)  Si(2)  C(2)  Yd)  84.7(4)  N(l)  Si(2)  C(16)  113 .1(5)  P(3)  C(3)  Si(3)  112.0(5)  C(2)  Si(2)  C(15)  117 .2(5)  P(4)  C(4)  Si(4)  114.3(6)  C(2)  Si(2)  C(16)  105 .8(5)  C(15)  Si(2)  C{16)  104 .3(6)  N(2)  Si(3)  C(18)  114 .1(5)  N(2)  Si(3)  C(17)  113 .9(4)  N(2)  Si(3)  C(3)  110 .6(4)  C(18)  Si(3)  C(17)  105 .8(5)  C(18)  Si(3)  C(3)  106 .9(5)  C(17)  Si ( 3 ) C(3)  105 .0(5)  N(2)  S i ( 4 ) C(4)  111 .7(4)  N(2)  Si(4)  Cd9)  113 • 9(5)  N{2)  Si(4)  C(20)  113 .8(5)  C(4)  Si(4)  Cd9)  106 .1(6)  C(4)  S i ( 4 ) C(20)  105 .6(6)  C(19)  S i ( 4 ) C(20)  105 .0(6)  Sid)  Nd)  Si(2)  127 .8(4)  Sid)  Nd)  Yd)  131 .2(4)  Si(2)  Nd)  Yd)  101 .0(3)  Si(3)  N(2)  Si(4)  122 .0(4)  Si(3)  N(2)  Yd)  122 .6(4)  Si(4)  N(2)  Yd)  115 .3(4)  Pd)  Cd)  Sid)  111 .5(5)  P(2)  C(2)  Si(2)  123 .3(6)  P(2)  C(2)  Y(l)  76. 8(4)  angle  155  A-2  Xray Crystallographic Analysis of {Y(Ti3-allyl)[N(SiMe CH2PMe2)2]h(u-Cl)2 2  156  formula  C 6H66Cl2N2P4Si Y2  crystal size , m m  0.13x0.25x0.37  crystal system  monoclinic  space group  P2 /a  a, A  12.0949(9)  2  l  b, A  14.2647(11) 13.278(2) 101.555(8)  cA  P,  deg  <y,A  4  2244.3(4)  3  z  D , g/cm c  2 1.320  3  radiation  Mo  wavelength (A) |1, c m "  0.71073 29.8 55.0  1  20  max>  d e  S  total no. of reflections no. of unique reflections no. of variables  5136 2272 181 0.035 0.038  R w  R  g.o.f. residual density e/A  3  1.15 0.46  157  Final positional (fractional x 10*; Y, CI, P, and Si x 10 ) 5  and isotropic thermal parameters (U x 10 A ) 3  2  with estimated standard deviations in parentheses Atom  z  y  X  Y  42306(  4)  45717(  3)  34398(  4)  41  Cl  4266200)  60283(  8)  4797700)  50  PO)  18189(11)  4647000)  34841O1)  53  P(2)  62229( 1 1 )  55287(  9)  30777(11)  53  SiO )  21354(13)  50876(12)  12831(12)  59  Si(2)  41735(13)  62584(  15244(11)  49  N  3451 (  3)  5364(  3)  1966(  3)  45  CO )  1 338 (  >  4400(  4)  21 28 (  4)  64  C(2)  5729(  4)  5952(  4)  1781 (  4)  57  C(3)  1282(  5)  581 0 (  4)  3647(  5)  73  C(4)  894(  4)  3941 (  4)  41 10( 4)  68  C(5)  6682(  5)  6586(  4)  3800(  4)  65  C(6)  7572(  5)  4945(  4)  3060(  5)  79  C(7)  1 233 ( 5)  6141 (  5)  830(  5)  88  C(8)  2166(  5)  4335(  5)  1 23 ( 5)  86  C(9)  3947(  4)  7389(  3)  2151 (  4)  59  COO)  3844(  5)  6477(  4)  97(  4)  78  C O D  3607(  5)  2837(  4)  3227 (  6)  79  C(12)  4203(  6)  2988(  4)  2453(  5)  75  C(13)  5287(  6)  3287(  4)  2582(  5)  66  4  9)  158  Bond l e n g t h s  0  (A) with  estimated  standard d e v i a t i o n s i n parentheses Bond Y  -CI  Length(A)  Bond  Length(A)  2.746(1)  P(2)-C(5)  1.813(6)  y  -Pd)  2.931(1)  P(2)-C(6)  1.835(6)  Y  -P(2)  2.892(1)  Si(1)-N  1.713(4)  Y  -N  2.292(4)  Sid)-C(l)  1.893(6)  y  -c(11)  2.587(5)  Si(1)-C(7)  1.884(6)  Y  -C(12)  2.609(5)  Si(D-C(8)  1.884(6)  y  -c(i3)  2.621(5)  Si(2)-N  1.715(4)  Y  -CI'  2.795(1)  Si(2)-C(2)  1.894(5)  y  - A  2.389(3)  Si(2)-C(9)  1.860(5)  P(1)-C(1)  1.812(6)  SK2)-C(10)  1.883(6)  P ( 1 )-C(3)  1.810(6)  C(1 1 ) - C d 2 )  1.387(9)  P ( 1 )-C(4)  1.825(5)  C( 12)-C(13)  1.356(8)  P(2)-C(2)  1.810(5)  159  Bond angles (deg) with estimated standard deviations i n parentheses*  Bonds CI CI CI CI CI  p(D  -Y -Y -Y -Y -Y -Y  P d ) -y  p(D - Y p(D -y  P(2) - Y P(2) -y P(2) - Y N -y N -y CI' -Y y -ci Y Y  -p(D -P(2)  -N  -CI'  -A  -P(2)  -N  -CI'  -A -N  -CI'  -A  -CI'  -A -A  -y  - P d ) -cd) - P d ) -C(3) - P d ) -CU)  y c d ) - p d ) -C(3) c d ) - P d ) -C(4) C(3) - P d ) -C(4) Y - P ( 2 ) -C(2)  Angle(deg) 81.02(4) 81.26(4) 97.88(9) 76.11(4) 161.9(1) 148.38(4) 76.01(10) 118.52(4) 100.7(1 ) 80.75(10) 81.94(4) 104.3(1 ) 162.37(10) 100.0(1 ) 87.5(1) 103.89(4) 95.5(2) 114.7(2) 133.8(2) 104.2(3) 104.0(3) 100.6(3) 100.9(2)  Bonds  Angle(deg)  Y -P(2)-C(5) Y -P(2)-C(6) C(2)-P(2)-C(5) C(2)-P(2)-C(6) C(5)-P(2)-C(6) N -Si(D-Cd) N -Si(l)-C(7) N -Si(D-C(8) C(1)-Si(1)-C(7) C(D-Si(l)-C(8) C(7)-Sid)-C(8) N -Si(2)-C(2) N -Si(2)-C(9) N -Si(2)-C(l0) C(2)-Si(2)-C(9) C(2)-Si(2)-Cd0) C(9)-Si(2)-Cd0) Y -N -Sid) Y -K -Si(2) Si(D-N -Si(2) P(1)-C(1)-Si(1) P(2)-C(2)-Si(2) C(1 1 ) - C d 2 ) - C ( 1 3 )  118.8(2) 124.1(2) 103.5(2) 105.3(3) 101.8(3) 109.6(2) 113.8(2) 113.3(2) 105.7(3) 106.6(3) 107.3(3) 108.8(2) 1 11.2(2) 116.6(2) 110.5(2) 102.8(3) 106.6(3) 121.2(2) 120.6(2) 118.2(2) 112.8(3) 112.0(2) 126.1(6)  * H e r e a n d e l s e w h e r e , p r i m e d atoms a r e r e l a t e d t o t h o s e i n T a b l e 1 by t h e c r y s t a l l o g r a p h i c i n v e r s i o n c e n t e r a n d A r e f e r s t o t h e c e n t r o i d of the a l l y l l i g a n d .  160  A-3  Xray Crystallographic Analysis of Hf(Ti4:nl-C7Hii)[N(SiMe CH2PPr 2)2] 2  i  161  formula  C H55NP Si Hf  crystal system space group  tetragonal  A b, A cA a,  u,A  3  25  2  W i 10.2288(5) 10.2288(5) 30.247(2) 3164.7(3)  z  4  radiation  CuK  no. of unique reflections  1809  R  0.052  R  w  a  0.046  2  162 Final positional  (fractional  x 1 0 * , Hf x 1 0  and i s o t r o p i c thermal parameters with estimated standard deviations Atom Hf P(1) P(2)  sid)  Si(2) N cd)  C(2) C(3) CU) C(5) C(6) C(7) C(B) C(9)  cdo)  C( 1 1 ) C( 12) C(13) C(14) C(15) C(16) C(17) C(18)  C(19) C(20) C(21 ) C(22) C(23) C(24) C(25)  y 8645( 9) 556( 6) 2487( 7) 3456( 6) 3625( 7) 2728(13) 2116(18) 3117(24) -687(26) 738(24) 2038(33) 3954(23) 4672(27) 4363(22) 5448(22) 3160(32) -2030(27) -371(34) -508(34) 1285(28) 1276(39) 1610(41) 3686(25) 5037(32) -466(22) -416(30) -993(33) -1479(25) -1684(31) -831(37) 541(27)  39907(10) 2164( 6) 5548( 6) 2637( 7) 2831( 6) 3064(12) 2504(20) 4194(26) 2058(30) 446(21 ) 6850(32) 6180(22) 3906(28) 1045(24) 2871(28) 1197(25) 2350(31 ) 2772(38) -76(30) -510(26) 7926(29) 6437(32) 7200(22) 6661 (31 ) 2596(24) 3799(31) 4976(34) 4923(30) 6084(31 ) 5943(34) 5533(25)  (U x 1 0 in  3  5  )  A ) 2  parentheses  2  25000 1833( 2) 3035( 2) 1976( 2) 2962( 2) 2487( 5) 1575( 6) 3341 ( 8) 1402( 10) 2028( 8) 3445( 10) 2767 ( 8) 1777( 8) 201 1 (7) 291 8( 9) 3220( 8) 1570( 9) 996( 11 ) 2252( 12) 1676( 11 ) 3221 ( 1 1 ) 3881 ( 12) 2435( 1 1 ) 3082( 1 1 ) 2906( 8) 31 47 ( 8) 2960( 19) 2542( 10) 2281 ( 13) 1866( 11 ) 1996( 9)  17  eq  /[/.  40 46 53 45 48 36 46 65 92 63 103 63 73 66 85 92 86 127 133 97 120 157 91 126 68 80 135 70 115 123 58 (  iso  7)  Bond l e n g t h s  ft  (A) w i t h  estimated  standard d e v i a t i o n s i n parentheses Length(A)  Bond  Bond  Length(A)  Hf  -P(1)  2.767(6)  Si(2)-N  1.72(2)  Hf  -P(2)  2.812(6)  Si(2)-C(2)  1.88(3)  Hf  -N  2.129(13)  Si(2)-C(9)  1 .87(2)  Hf  -C(19)  2.32(2)  Si(2)-Cd0)  1.90(3)  Hf  -C(20)  2.36(2)  C(3)-C(11)  1.49(4)  Hf  -C(21)  2.56(3)  C(3)-C(12)  1.47(4)  Hf  -C(22)  2.58(3)  C(4)-C(13)  1.54(3)  Hf  -C(25)  2.22(3)  C(4)-C(14)  1.55(3)  P(1 ) - c d )  1.81(2)  C(5)-C(15)  1.51(4)  P(1)-C(3)  1.83(3)  C(5)-C(16)  1.45(4)  P(1)-C(4)  1.86(2)  C(6)-C(17)  1.47(3)  P(2)-C(2)  1.79(3)  C(6)-C(18)  1.54(3)  P(2)-C(5)  1.8B(2)  C(19)-C(20)  1.43(3)  P(2)-C(6)  1.82(3)  C(20)-C(21 )  1.45(5)  Si(1)-N  1.77(2)  C(21)-C(22)  1.36(5)  Si(1)-C(1 )  1.83(2)  C(22)-C(23)  1.44(4)  Sid)-C(7)  1.90(3)  C(23)-C(24)  1.53(4)  1.88(2)  C(24)-C(25)  1.52(4)  Si(1)-C(8)  .  Bond angles  (deg) with estimated  standard deviations i n parentheses Bonds P(1)-Hf -P(2) P(1)-Hf -N P(1)-Hf -C(19) P(1)-Hf -C(20) P(1)-Hf -C(21) P(1)-Hf -C(22) P(1)-Hf -C(25) P(2)-Hf -N P(2)-Hf -C(19) P(2)-Hf -C(20) P(2)-Hf -C(21) P(2)-Hf -C(22) P(2)-Hf -C(25) N -Hf -C(19) N -Hf -C(20) N -Hf -C(21) N -Hf -C(22) N -Hf -C(25) C(19)-Hf -C(20) C(l9)-Hf -C(21 ) C(l9)-Hf -C(22) C(l9)-Hf -C(25) C(20)-Hf -C(21) C(20)-Hf -C(22) C(20)-Hf -C(25) C(21)-Hf -C(22) C(21)-Hf -C(25) C(22)-Hf -C(25) Hf -P(1 l-C(1 ) Hf -P(1 »-C(3) Hf -P(1 >-C(4) C(1)-P(1 >-C(3) C(1)~P(1 )-C(4) C(3)-P(1 >-C(4) Hf -P(2 >-C(2) Hf -P(2 >-C(5) Hf -P(2 >-C(6) C(2)-P(2 >-C(5) C(2)-P(2 l-C(6) C(5)-P(2 >-C(6) N -Si( l ) - C ( 1 )  Angle(deg)  Bonds  150.31[2) 77.8 (4) 84.4 [6) 119.0 [7) 125.2 [10) 100.3 (7) 87.8 [7) 74.6 [4) 112.9 (7) 84.1 [7) 84.4 (10) 108.1 (7) 94.6 (7) 105.1 [7) 118.4 (9) 148.1 (14) 174.9 (8) 115.9 (8) 35.6 (8) 61.3 (10) 69.9 (9) 135.4 (9) 34.1 (12) 58.4 (10) 123.0 (12) 30.7 (12) 89.0 (12) 68.5 (9) 94.8 (7) 129.9 (10) 113.3 (7) 108.5 (12) 103.2 (11) 103.8 (12) 94.1 (8) 129.6 (11) 115.5 (7) 107.3 (14) 102.0 (11) 104.0 (13) 106.3 (8)  N -Si(1)-C(7) N -Sid)-C(8) C(1)-Si(1)-C(7) C(1)-Si(l)-C(6) C(7)-Si(1)-C(8) N -Si(2)-C(2) N -Si(2)-C(9) N -SU2)-C(10) C(2)-Si(2)-C(9) C(2)-Si(2)-C(l0) C(9)-Si(2)-C(l0) Hf -N -Si(1) Hf -N -Si(2) Si(D-N -Si(2) P(1)-C(1)-Si(D P(2)-C(2)-Si(2) P(1)-C(3)-C(11) P(1)-C(3)-C(12) C(11)-C(3)-C(12) P(1 )-C(4)-C(13) P( 1 )-C(4)-C(14) C(13)-C(4)-C(14) P(2)-C(5)-C(15) P(2)-C(5)-C(16) C(15)-C(5)-C(16) P(2)-C(6)-C(17) P(2)-C(6)-C(18) C(17)-C(6)-C(18) Hf -C(19)-C(20) Hf -C(20)-C(19) Hf -C(20)-C(21) C(19)-C(20)-C(21) Hf -C(21)-C(20) Hf -C(21)-C(22) C(20)-C(21)-C(22) Hf -C(22)-C(21) Hf -C(22)-C(23) C(21)-C(22)-C(23) C(22)-C(23)-C(24) C(23)-C(24)-C(25) Hf -C(25)-C(24)  Angle(deg) 112.6(9) 111.8(8) 109.4(11) 110.0(10) 106.7(12) 105.0(9) 117.9(10) 109.3(10) 107.7(12) 109.5(12) 107.3(13) 120.2(8) 121.5(9) 118.1(8) 112.8(11 ) 111.1(13) 113(2) 115(2) 113(3) 113(2) 114(2) 112(2) 110(2) 118(3) 118(3) 114(2) 116(2) 109(2) 73.8(13) 70.6(13) 80(2) 120(3) 65.5(14) 76(2) 118(4) 74(2) 114(2) • 122(4) 107(2) 110(3) 121(2)  165  A-4  Xray Crystallographic Analysis of Zr(Ti4:nl-C8Hi3)[N(SiMe CH2PPr*2)2] 2  166  A. Empirical  C r y s t a l Data C  Formula  2 6  H  5 7  NP Si Zr 2  2  Formula Weight  593.08  C r y s t a l Color, Habit  dark, p r i s m  C r y s t a l Dimensions  0.200  Crystal  (mm)  System  X 0.320  X  0.480  triclinic  No. R e f l e c t i o n s Used f o r U n i t C e l l D e t e r m i n a t i o n ( 2 e range) Omega Scan Peak Width at H a l f - h e i g h t  25  ( 28.0 -  34.0°)  0.51  L a t t i c e Parameters: a b c a P Y  •= -  V Space  F  1628 ( 1 ) A  3  P i (#2)  Group  2  Z value D  11.028 ( 2)A 15.796 (2)A 10.596 (2)A 104.59 (1)° 108.46 (2)° 100.07 (1)°  1.210  calc  g/cm  3  636  000  5.15  ^(MoKa)  B.  Intensity  cm~*  Measurements  DiffTactometer  Rigaku AFC6S  Radiation  MoKa (X « 0.71069 A)  Temperature  21°C  T a k e - o f f Angle  6.0'  167 Detector  Aperture  Crystal  t o Detector  Scan  Distance  Type  6.0 6.0  sun h o r i z o n t a l sun v e r t i c a l  285  mm  co-26  Scan Rate  32.0°/min ( i n omega) (8 r e s c a n s )  Scan W i d t h  (1.21  26. max  55.0°  No.  Total: 7841 Unique: 7449 (R  of R e f l e c t i o n s Measured  C.  Structure  Patterson  Refinement Minimized  Method  Full-matrix  least-squares  I w (|Fo| -  |Fc | )  Least-squares Weights  4Fo /o (Fo )  p-factor  0.05  Anomalous  Reflection/Parameter R;  R  All  (I>3.00e(I))  No. O b s e r v a t i o n s No. V a r i a b l e s  Goodness  2  Dispersion  Residuals:  .030)  S o l u t i o n and R e f i n e m e n t  Solution  Function  int -  Lorentz-polarization Absorption ( t r a n s , f a c t o r s : 0.60 - 1. Decay ( -3.00% d e c l i n e )  Corrections  Structure  + 0.35 tan6)°  2  2  non-hydrogen atoms  4775 307  15.55  Ratio  0.058;  0.071  w  1.81  of F i t Indicator  Max S h i f t / E r r o r i n F i n a l Maximum Peak i n F i n a l Minimum Peak i n F i n a l  Cycle  Diff. Diff.  Map Map  0.03  1.77 -1.40  2  e~/k\  e"/A  3  168 Final  atom  atomic c o o r d i n a t e s  X  y  (fractional)  z  and  B  B  eq  i  Zr(l)  0 .47987(4)  0. 20725(3)  0 .27390(5)  3.64(2)  P(D  0 .7441(1)  0. 26257(8)  0 .4596(1)  4.20(4)  P(2)  0 .2716(1)  0. 23657(8)  0.0631(1)  4.40(4)  S i d )  0.7052(1)  0. 39904(8)  0 .3049(1)  4.28(4)  Si(2)  0.5310(1)  0. 27322(8)  0 .0135(1)  3 .86(4)  N(l)  0 .5799(4)  0. 3016(2)  0 .1943(4)  3.7(1)  Cd)  0 .7745(5)  0. 3841(3)  0 .4818(5)  4 .6(2)  C(2)  0 .3471(5)  0. 2110(4)  -0 . 0 6 7 1 ( 5 )  5.0(2)  C(3)  0 .8095(6)  0. 2523(4)  0 .6386(6)  6 .1(2)  C(4)  0 .8677(5)  0. 2306(4)  0 .3850(6)  5 .1(2)  C(5)  0 .0919(5)  0. 1753(4)  -0 . 0 3 3 2 ( 7 )  6.3(2)  C(6)  0 .2736(5)  0. 3579(4)  0.0876(7)  6 .0(2)  C(7)  0 .8465(5)  0. 4240(4)  0 .2444(7)  6 .3(2)  C(8)  0 .6446(7)  0. 5026(4 )  0 .3339(7)  6 .9(2)  C(9)  0 .5506(6)  0. 3718(4 )  -0 . 0 5 3 3 ( 6 )  5 .5(2)  C(10)  0.6200(6)  0. 1950(4)  -0 . 0 5 5 7 ( 6 )  5.5(2)  C(ll)  0 .8084(8)  0. 3303(6)  0 .7536(7)  8 .4(3)  C(12)  0 .7380(7)  0. 1593(5)  0 .6376(7)  7 .2(3)  C(13)  0.8699(6)  0. 1323(4)  0 .3688(7)  6 .7(2)  C(14)  1 .0088(6)  0. 2926(4)  0 .4608(7)  6 .6(2)  C(15)  0 .0664(7)  0. 0808(5)  -0 . 1 2 6 3 ( 8 )  8 .6(3)  C(16)  0 .0159(6)  0. 1770(5)  0 .0637(8)  7.4(3)  C(17)  0 .236(1)  0. 3998(5)  0 .211(1)  9 .7(4)  C(18)  0 .1984(8)  0. 3776(5)  -0 . 0 4 6 ( 1 )  9 .5(3)  169  Final atomic coordinates ( f r a c t i o n a l ) and B atom  X  y  z  B  eq  C(19)  0 .4454(6)  0 .2849(3)  0.4692(6)  5.5(2)  C(20A)  0 .374(2)  0 .233(1)  0. 5 4 2 ( 1 )  5.0(4)  C(20B)  0 .343(3)  0 .245(2)  0 .486(3)  5(1)  C(21A)  0 .2807(9)  0 .1411(6)  0 .448(1)  4.4(3)  C(21B)  0 .347(2)  0 .150(2)  0.509(2)  4.4(7)  C(22)  0 .3599(7)  0 .0981(4)  0.3680(7)  6.4(2)  C(23)  0 .3032(6)  0 .0664(3)  0. 2 2 3 2 ( 8 )  6.3(2)  C(24)  0 .3787(6)  0 .0521(3)  0. 1 3 9 0 ( 6 )  5.1(2)  C(25)  0 .5190(6)  0 .0646(3)  0 .2061(6)  5.2(2)  C(26)  0 .2247(7)  0 .0881(5)  0. 5 1 8 4 ( 8 )  7.5(3)  170 Bond l e n g t h s (A) w i t h e s t i m a t e d i n parentheses.  standard  deviations  atom  atom  distance  atom  atom  distance  Zr(l)  Pd)  2.782(2)  Si(2)  C(10)  1 .857(5)  Zr(l)  P(2)  2.850(2)  C(3)  Cdl)  1 .503(9)  Zr(l)  N(l)  2.190(4)  C(3)  C(12)  1 .54(1)  Zr(l)  C(19)  2.305(5)  C(4)  C(13)  1 .524(8)  Zr(l)  C(22)  2.573(5)  C(4)  C(14)  1 .519(8)  Zr(l)  C(23)  2.500(5)  C(5)  C(15)  1 .49(1)  Zr(l)  C(24)  2.358(4)  C(5)  C(16)  1 .515(9)  Zr(l)  C(25)  2.345(5)  C(6)  C(17)  1 .52(1)  Pd)  Cd)  1.831(5)  C(6)  C(18)  1 .53(1)  Pd)  C(3)  1.864(6)  C(19)  C(20A)  1 .54(2)  Pd)  C(4)  1.860(5)  C(19)  C(20B)  1 .28(4)  P(2)  C(2)  1.823(5)  C(20A) C(21A)  1 .51(2)  P(2)  C(5)  1.860(5)  C(20B) C(21B)  1 .59(4)  P(2)  C(6)  1.864(6)  C(21A) C(22)  1 .52(1)  Sid)  N(l)  1.724(4)  C(21A) C(26)  1 .44(1)  Sid)  Cd)  1.879(6)  C(21B) C(22)  1 .57(2)  Sid)  C(7)  1.881(6)  C(21B) C(26)  1 .57(2)  Sid)  C(8)  1.865(6)  C(22)  C(23)  1 .376(9)  Si(2)  N(l)  1.730(4)  C(23)  C(24)  1 .405(8)  Si(2)  C(2)  1.895(5)  C(24)  C(25)  1 .437(8)  Si(2)  C(9)  1.873(6)  171 Bond a n g l e s ( d e g ) w i t h e s t i m a t e d s t a n d a r d d e v i a t i o n s i n parentheses. atom  atom  atom  angle  149 .26(4)  C(23)  Zr(l)  C(25)  60 .6(2)  N(l)  76 .1(1)  C(24)  Zr(l)  C(25)  35 .6(2)  Zr(l)  C(19)  83 .4(2)  Zr(l)  Pd)  C(l)  97 .4(2)  Pd)  Z r (1)  C(22)  104 .4(2)  Zr(l)  Pd)  C(3)  127 .1(2)  Pd)  Zr(l)  C(23)  128 • 4(2)  Zr(l)  Pd)  C(4)  116 .7(2)  Pd)  Zrd)  C(24)  119 .6(1)  C(l)  Pd)  C(3)  107 .4(3)  Pd)  Z r (1)  C(25)  84 .5(1)  Cd)  Pd)  C(4)  102 .4(2)  P(2)  Zrd)  N(l)  74 .6(1)  C(3)  Pd)  C( 4 )  102 .7(3)  P(2)  Zrd )  C(19)  98 .5(2)  Zr(l)  P(2)  C(2)  93 .0(2)  P(2)  Zr(l)  C(22)  104 .8(2)  Zr(l)  P(2)  C(5)  132 .6(2)  P(2)  Zr(l)  C(23)  82 .3(2)  Zr(l)  P(2)  C(6)  115 .4(2)  P(2)  Zr(l)  C(24)  84 .1(1)  C(2)  P(2)  C(5)  105 .2(3)  P(2)  Zr {1)  C(25)  114 .5(1)  C(2)  P(2)  C(6)  102 .9(3)  N(l)  Zr(l)  C(19)  111 .1(2)  C(5)  P(2)  C(6)  102 .9(3)  N( 1)  Zr (1)  C(22)  179 .0(2)  N(l)  Sid)  C(l)  107 .6(2)  N(l )  Zr(l)  C(23)  148 .7(2)  N(l)  Sid)  C(7)  114 .2(2)  N(l )  Zr (1)  C(24)  121 .5(2)  N(l)  Sid)  C(8)  112 .9(2)  N(l )  Zr(l)  C(25)  110 .5(2)  Cd)  Si(l)  C(7)  107 .9(3)  C(19)  Zr(l)  C(22)  68 .2(2)  C(l)  Si(l)  C(8)  106 .6(3)  C(19)  Zr(l)  C(23)  92 .9(2)  C(7)  Si(l)  C(8)  107 .3(3)  C(19)  Z r (1)  C(24)  125 .8(2)  N(l)  S i (2)  C(2)  107 .2(2)  C(19)  Z r (1)  C(25)  132 .2(2)  N(l)  Si(2)  C(9)  115 .4(2)  C(22)  Z r (1)  C(23)  31 .4(2)  N(l)  Si(2)  C(10)  111 .6(2)  C(22)  Zr(l)  C(24)  59 .1(2)  C(2)  Si(2)  C(9)  106 .6(3)  C(22)  Z r (1)  C(25)  70 .4(2)  C(2)  Sid)  C(10)  107 .7(2)  C(23)  Zr(l)  C(24)  33 .5(2)  C(9)  Sid)  C(10)  108 .0(3)  atom  atom  atom  Pd)  zr(l)  P(2)  Pd)  Z r (1)  Pd)  angle  172 atom  atom  atom  2r(l)  Nd)  Sid)  Zr(l)  Nd)  Sid)  atom  atom  122.3(2)  C(22)  C(21B) C(26)  107(1)  Si(2)  117.1(2)  Zr(l)  C(22)  C(21A)  113 .2(4)  Nd)  Si(2)  120.5(2)  Zr(l)  C(22)  C(21B)  112 .1(8)  Pd)  Cd)  Sid)  109.5(2)  Zr(l)  C(22)  C(23)  71 .4(3)  P(2)  C(2)  Si(2)  110.4(3)  C(21A) C(22)  C(23)  117 .8(7)  Pd)  C(3)  Cdl)  113.9(5)  C(21B) C(22)  C(23)  147(1)  Pd)  C(3)  C(12)  110.2(4)  Zr(l)  C(23)  C(22)  77 .2(3)  Cdl)  C(3)  C(12)  112.6(6)  Zr(l)  C(23)  C(24)  67 .7(3)  Pd)  C(4)  C(13)  112.3(4)  C(22)  C(23)  C(24)  122 .5(6)  Pd)  C(4)  C(14)  115.9(4)  Zr(l)  C(24)  C(23)  78 .8(3)  Cd3)  C(4)  C(14)  109.4(5)  Zr(l)  C(24)  C(25)  71 .7(3)  P(2)  C(5)  C(15)  113.6(5)  C(23)  C(24)  C(25)  118 .9(5)  P(2)  C(5)  C(16)  112.7(4)  Zr(l)  C(25)  C(24)  72 .7(3)  Cd5)  C(5)  C(16)  111.1(5)  P(2)  C(6)  C(17)  112.4(5)  P(2)  C(6)  C(18)  115.5(5)  Cd7)  C(6)  C(18)  112.5(6)  Zrd)  Cd9)  C(20A)  120.8(6)  Zrd)  Cd9)  C(20B)  115(1)  Cd9)  C(20A) C(21A)  114.2(9)  C(19)  C(20B) C(21B)  114(2)  angle  C(20A) C(21A) C(22)  104.0(8)  C(20A) C(21A) C(26)  114.7(8)  C(21A) C(26)  116.3(7)  C(22)  C(20B) C(21B) C(22)  100(2)  C(20B) C(21B) C(26)  121(2)  atom  angle  173  A-5  X r a y Crystallographic  Analysis of  {ZrCl[N(SiMe CH PPr 2)2]}2(lt-'n :Tl -N2) l  2  2  2  2  174  A. Empirical  C r y s t a l Data  Formula  C  Formula Weight Crystal Color,  4 3  H  9 6  C  l  2  N  Crystal  monoclinic  System  No. R e f l e c t i o n s Used f o r U n i t C e l l D e t e r m i n a t i o n (26 range)  25  Omega S c a n Peak W i d t h at H a l f - h e i g h t  0.38  (  -  V -  X  0.200  65.0  -  14.103 16.233 14.678 114.24 3064  4  Z  r  2  0.200  X  (3)A (3)A (3)A (l)  (1)A  P2 /c (#14)  Z  2  e  3  1  value  ooo  i  8 7 . 3 ° )  Space G r o u p  F  S  Parameters: a b c 0  calc  4  dark, p l a t e  Habit  0.050  D  P  1158.84  C r y s t a l Dimensions (mm)  Lattice  4  1.256 g/cm  3  1224 56.60 cm"  "(CuKa)  B  1  I n t e n s i t y Measurements  DiffTactometer  Rigaku AFC6S  Radiation  CuKa (X - 1.54178 A)  Temperature  21°C  Take-off Angle  6.0  Detector Aperture  6.0 mm h o r i z o n t a l 6.0 mm v e r t i c a l  e  175 C r y s t a l to Detector  285  Distance  mm  Scan Type  u>-2 6  Scan Rate  16.0*/min ( i n omega) (8 rescans)  Scan Width  (1.00 + 0.20  26  155.5° max  Total:  No. of R e f l e c t i o n s Measured  Structure  7046  Unique: 6783 ( * - .035) Lorentz-polarization Absorption ( t r a n s , f a c t o r s : 0.43 - 1.00) Secondary E x t i n c t i o n (coefficient: 0.10352E-05) i n t  Corrections  C.  tan6)°  S t r u c t u r e S o l u t i o n and Refinement Patterson  Solution  Method  Refinement  Full-matrix  least-squares  Function Minimized  I w (|Fo| -  |Fc|)  L e a s t - s q u a r e s Weights  2 2 2 4FO / a (FO^)  p-factor  0.03  Anomalous D i s p e r s i o n  All  No. O b s e r v a t i o n s (l>3.00o(I)) No. V a r i a b l e s Reflection/Parameter Ratio  4158 303 13.72  Residuals:  0.040; 0.049  R;  R  w  1.71  Goodness of F i t I n d i c a t o r Max  Shift/Error in Final  non-hydrogen  Cycle  Maximum Peak i n F i n a l D i f f . Minimum Peak i n F i n a l D i f f .  Map Map  0.01 0.47 -0.50  e~/k\  e"/A  3  2  atoms  176  Final atomic coordinates and B atom  y  (A ) 2  e g  z  occ.  Zrd)  0.36881(3)  0.52543(2)  0.53352(3)  3.74(1)  C l d )  0.4091(1)  0.65841(8)  0.6246(1)  6.86(6)  Pd)  0.2406(1)  0.60517(8)  0.3711(1)  5.11(5)  P(2)  0.4157(1)  0.45534(8)  0.7147(1)  5.42(6)  S i d )  0.1950(1)  0.4197(1)  0.3547(1)  6.17(6)  Si  0.3128(5)  0.3299(4)  0.5400(5)  5.7(2)  0 . 565  Si(2A)  0.2785(6)  0.3426(5)  0.5523(7)  5.8(3)  0 . 435  N d )  0.2782(3)  0.4245(2)  0.4785(3)  4.3(1)  NU)  0.4722(3)  0.5225(2)  0.4494(3)  4.7(1)  Cd)  0.1998(4)  0.5178(3)  0.2886(4 )  6.1(2)  C(2)  0.3918(6)  0.3496(4)  0.6777(4)  8.0(3)  C( 3)  0.2885(6)  0.6818(4 )  0.3073(5)  7.8(3)  C(4 )  0.1248(6 )  0.6474(6)  0.3814(6)  9.8(4)  C(5)  0.5487(6)  0.4569(4 )  0.8168(5)  8.7(3)  C(6)  0.3277(8)  0.4885(7)  0.7701(7 )  12.1(6)  C(7)  0.0578(6)  0.4009(7)  0.3356(7)  16.1(6 )  C(8)  0.228(1)  0.3397(5)  0.2840(6)  16.1(7 )  C(9)  0.197(1)  0.265(1)  0.526(1)  10.4(9)  0 . 565  COA)  0.154(1)  0.329(1)  0.569(1)  10(1)  0 . 435  CdO)  0.394(1)  0.2636(8)  0.498(1)  9.5(7)  0 . 565  CdOA)  0.301(2)  0.2438(8)  0.506(1 )  9.8(9)  0 . 435  C d l )  0.3290(8)  0.7577(5)  0.3685(6)  12.9(5)  C(12)  0.2191(7)  0.7014(5)  0.2013(5)  11.8(5)  C(13)  0.0272(7)  0.6512(7)  0.2863(8)  15.0(7)  (2)  177 Final atom  a t o m i c c o o r d i n a t e s and B  X  y  (A  )  (cont.)  z  occ.  C(14)  0. 1 0 9 ( 1 )  0. 6 1 8 ( 2 )  0. 4 6 8 ( 2 )  15(1)  0.540  C(14A)  0. 1 3 4 ( 2 )  0. 7 0 9 ( 2 )  0. 4 4 5 ( 2 )  15(1)  0.460  C(15)  0. 5 8 4 6 ( 7 )  0. 5 4 1 9 ( 5 )  0. 8 5 2 4 ( 6 )  11.6(4)  C(16)  0. 5 6 9 6 ( 8 )  0. 3 9 7 8 ( 5 )  0. 9 0 1 5 ( 6 )  12.8(5)  C(17)  0. 2 3 9 ( 1 )  0. 5 2 6 4 ( 9 )  0. 7 0 8 ( 1 )  21(1)  C(18)  0. 3 0 2 ( 1 )  0. 4 2 9 ( 1 )  0. 8 3 2 ( 1 )  21(1)  C(19)  - 0 . 040(4)  0. 0 5 6 ( 2 )  0. 5 2 2 ( 2 )  28(2)  C(20)  0. 0 3 3 ( 3 )  0. 0 7 4 ( 2 )  0. 5 0 7 ( 2 )  27(2)  C(21)  0. 0 7 5 ( 3 )  0. 022(4 )  0. 4 7 6 ( 2 )  25(2)  C(22)  - 0 . 111(2)  0. 0 7 6 ( 2 )  0. 548(2 )  17(1)  0. 500  178 Bond l e n g t h s  (A)  with estimated standard  deviations.*  atom  atom  d i stance  atom  atom  distance  Zr(l)  Cl(l)  2.493(1)  Si(2)  C(10)  1.86(2)  Zr(l)  Pd)  2.764(1)  Si(2A) N ( l )  1.71(1)  Zr(l)  P(2)  2.772(1)  Si(2A) C(2)  1.88(1)  Zr(l)  N(l)  2.175(3)  S i ( 2 A ) C(9A)  1.88(2)  Zr(l)  N(2)  2.024(4)  S i ( 2 A ) C(10A)  1.62(2)  Zr(l)  Nd)'  2.027(4)  N(2)  N(2) '  1.548(7)  Pd)  C(l)  1.800(5)  C(3)  C(ll)  1.49(1)  Pd)  CO)  1.844(6)  C(3)  C(12)  1.494(9)  Pd)  C(4)  1.834(7)  C(4)  C(13)  1.51(1)  P(2)  Cd)  1.790(6)  C(4)  C(14)  1.45(2)  P(2)  C(5)  1.859(7)  C(4 )  C(14A)  1.34(2)  Pd)  C(6)  1.621(8)  C(5)  C(15)  1.49(1)  Sid)  N(l )  1.713(4 )  C(5)  C(16)  1.50(1 )  Sid)  Cd)  1.880(5)  C(6)  C(17)  1.36(1 )  Si(l)  C(7)  1.863(9)  C(6)  C(18)  1.47(1 )  Sid)  C(8)  1.840(8)  C(19)  C(20)  1.18(6)  Sid)  Nd)  1.746(8)  C(19)  C(21)"  1.36(5)  Sid)  Cd)  1.89(1)  C(19)  C(22)  1.26(6 )  Sid)  C(9)  1.88(1)  C(20)  C(21)  1.23(7)  * Here and elsewhere the symbols ' and " r e f e r t o symmetry operations: l - x d - y , l - z ;  and -x»-y_#l-z; r e s p e c t i v e l y .  179  Bond angles (deg) w i t h e s t i m a t e d standard d e v i a t i o n s . atom  atom  atom  86 .39(5)  C(5)  P(2)  C(6)  106 .5(4)  84 .27(5)  N(l)  Si(l)  Cd)  110 .8(2)  139 .3(1)  N(l)  •Sid)  C(7)  112 .6(3)  Nd)  112 .3(1)  N(l)  Sid)  C(8)  114 .1(4)  Zrd)  Nd) '  111 .9(1)  Cd)  Si(l)  C(7)  108 .4(3)  Pd)  Zr(l)  Pd)  141 .00(5)  C(l)  Si(l)  C(8)  103 .6(3)  P(l)  Zrd)  N(l)  81 .9(1)  C(7)  Sid)  C(8)  106 .8(6)  Pd)  Zr(l)  Nd)  84 .7(1)  N(l)  Si(2)  C(2)  108 .7(4)  Pd )  Zr(l)  Nd) '  129 .6(1)  N(l )  Sid)  C(9)  113 .0(6)  Pd)  Zr (1)  N(l )  80 .9(1)  N(l)  Sid)  CdO)  114 .6(5)  Pd)  Zr(l)  N(2 )  133 .7(1)  C(2)  Si(2)  C(9)  108 .4(6)  Pd)  Zr (1)  Nd) '  88 .8(1)  C(2)  Sid)  CdO)  106 .4(6)  N(l)  Zr(l)  Nd)  105 .2(1)  C(9 )  Si(2)  C(10)  105 .4(8)  Nd)  Zr(l)  N( 2 ) '  105 .5(2)  N(l)  S i ( 2 A ) C(2)  110 .6(5)  Nd)  Zr (1)  Nd) '  44 .9(2)  N(l )  Si(2A) C(9A)  114 .4(8)  Zr(l)  Pd)  Cd)  97 .5(2)  N(l)  Si(2A) CdOA)  113 .5(8)  Zrd )  Pd)  C(3)  116 .7(2)  C(2)  S i ( 2 A ) C(9A)  110 .0(7)  Zrd )  Pd)  C(4)  119 .2(3)  C(2)  S i ( 2 A ) C(lOA)  102 .2(8)  Cd)  Pd)  C(3)  105 .8(3)  C(9A)  S i ( 2 A ) C(10A)  105(1)  Cd)  Pd)  C(4)  107 .5(4)  Zr(l)  N(l)  Si(l)  120 .2(2)  C(3)  Pd)  C(4)  108 .3(4)  Zr(l)  N(l)  Sid)  117 .7(3)  Zr(l)  Pd)  C(2)  99 .7(2)  Zr(l)  N(l )  Si(2A)  122 .3(4)  Zrd)  Pd)  C(5)  117 .5(2)  Sid)  N(l )  Sid)  115 .6(3)  Zr(l)  Pd)  C(6)  117 .2(3)  Sid)  N(l )  Si(2A)  117 .2(4)  Cd)  Pd)  C(5)  105 .1(3)  Zr(l)  N( 2 )  Zr(l)'  135 .1(2)  Cd)  P(2)  C(6)  109 .9(4)  Zr(l)  N(2)  N(2) '  67 .6(2)  atom  atom  atom  Cl(l)  Zr(l)  Pd)  CHI)  Zr(l)  P(2)  Cl(l)  Zr(l)  N(l)  Cl(l)  Zr(l)  Cl(l)  .angle  angle  180 Bond angles (deg) w i t h estimated standard atom  atom  atom  angle  Zr(l)  Nd)'  N(2)  67.5(2)  P(l)  C(l)  Sid)  112.9(3)  P(2)  C(2)  Si(2)  116.1(4)  P(2)  C(2)  Si(2A)  109.4(4)  Pd)  C(3)  C(ll)  112.4(5)  Pd)  C(3)  C(12)  116.9(5)  Cdl)  C(3)  C(12)  112.1(6)  Pd)  C(4)  C(13)  116.4(6)  Pd )  C(4)  C(14)  114.2(8)  Pd)  C(4)  C(14A)  120(1)  C(13)  C(4)  C(14)  115(1)  Cd3)  C(4)  C(14A)  114(1)  P(2)  C(5)  C(15)  112.4(5)  P(2 )  C(5)  C(16)  116.6(6)  C(15)  C(5)  C(16)  112.2(6)  P(2)  C(6)  C(17)  116.2(8)  P(2)  C(6)  C(18)  117.9(8)  C(17).  C(6)  C(18)  109(1)  C(20)  C(19)  C(21)"  125(4)  C(20)  C(19)  C(22)  149(6)  Cdl)"  C(19)  C(22)  85(6)  C(19)  C(20)  C(21)  120(3)  C(21)  C(20)  114(4)  C(19)  n  atom  atom  deviations,  atom  angle  181  WHY?  

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