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The structure and reactivity of poly(methylenephosphine)s Gillon, Bronwyn Hilary 2008

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THE STRUCTURE AND REACTIVITY OF POLY(METHYLENEPHOSPHINE)S  by BRONWYN HILARY GILLON  B.Sc., The University of British Columbia, 2002  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY  in  THE FACULTY OF GRADUATE STUDIES  (Chemistry)  THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) October 2008  © Bronwyn H. GilIon, 2008  Abstract  The initiation and termination steps of the anionic polymerization of P=C bonds have been modeled. The initiation step was investigated through the stoichiometric reaction of 2 (1) with RL1 (R MesPCPh  Me or n-Bu). In each case, the addition was highly regioselective  ] (R 2 with the formal attack of R at phosphorus to give the carbanion Li[Mes(R)P—CPh  =  Me  (3a); n-Bu (3b)). To simulate the termination step, carbanions 3a and 3b were quenched in situ  with various electrophiles:  H (4b), Mes(Me)P— 2 H (4a), Mes(n-Bu)P—CPh 2 Mes(Me)P—CPh  —P(NEt (7a), 2 Mes(Me)P—CPh ) —SiMe (8a) and Mes(Me)P— Mes(Me)P—CPh H Me (6a), 2 2 CPh —SiMe (9a). 2 CPh 3  The first use of MALDI-TOF MS in the study of the products of RLi (R  =  Me, n-Bu)  ]H with 2 initiated oligomerization of I is reported. The detected linear products R[MesP(=O)-CPh R—P and C—H end-groups are consistent with a chain growth mechanism. The oligomerization was extended to other monomers (MesP=CPhAr, Ar  =  F or p-C 4 H 6 p-C OMe). The results 4 H 6  suggest oligomers undergo fragmentation during MALDI-TOF analysis.  6 (M The thermal reactions of M(CO)  =  W, Mo, Cr) with polymer n-Bu[MesP-CPh ]H (10) 2  and its model compound 4a are reported. IR was primarily used to determine the success of metal coordination in the polymer. EDXISEM and GPC-LLS were used to determine metal content of the materials. Most metallation was modest (>10%), however, as much as 20% was attained with Mo.  The phosphorus-containing polymer 10 was found to be an effective ligand for gold(l) to afford n-Bu[MesP(AuCl)—CPh ]H 11, a new class of macromolecule with high gold content. The 2 prepared  model  compound  H 2 MeMesP(AuCI)—CPh  crystallography and NMR spectroscopy.  12  was  characterized  by  X-ray  Block copolymers containing phosphorus atoms in the backbone were prepared and metallated with gold(l). The living polymerization of isoprene (I) and then phosphaalkene I affords block copolymers Plmb[Me5PCPh In (13a: m 2  =  308, n  =  46; 13b: m  =  222, n  =  77).  Treating P1mb[MeSPCPh In with (tht)AuCI results in gold-containing macromolecules [Pl]mb 2 ] (14a and 14b). Upon dissolution in a polyisoprene selective solvent (n 2 [MesP(AuCl)-CPh heptane), the metallated block copolymers assembled into micelles (14a: spherical; 14b: worm like). The solution self-assemblies were examined by TEM and DLS.  III  Table of Contents Abstract  .  ii  Table of Contents  iv  List of Tables  x  Listof Figures  xi  List of Symbols and Abbreviations  xiii  Acknowledgments  xvi  Dedication  xviii  Statement of Co-authorship  xix  Chapter 1 1  Introduction 1.1  Phosphorus  1  1.2  Polymers  4  1.2.1  Inorganic Polymers  5  1.2.2  Hybrid Phosphorus-Carbon Polymers  7  1.3  History of Poly(methylenephosphine)s  11  1.4  Inorganic Micelles  18  1.5  Outline of Thesis  20  1.6  References  22  Chapter 2 Molecular Studies of the Initiation and Termination Steps of the Anionic Polymerization of PC bonds* 2.1  27 Introduction  27 iv  2.2 Preparation of Model Compounds  .29  2.2.1 General Preparation of Carbanions Li[Mes(R)P—CPh ] (2.3a and 2.3b) 2  29  2.2.2 Preparation of Mes(Me)P—CPh H (2.4a) 2  30  2.2.3 Preparation of Mes(n-Bu)P—CPh H (2.4b) 2  31  2.2.4 Preparation of 2 Mes(Me)P—CPh M e (2.6a)  32  2.2.5 Preparation of ) --P(NEt (2.7a) Mes(Me)P—CPh 2  32  2.2.6 Preparation of R —S1Me (2.8a and 2.9a) 2 Mes(Me)P—CPh  34  2.3 Conclusion  36  2.4 Experimental  37  2.4.1 Materials and General Procedures  37  2.4.2 Preparation of 2 Mes(Me)P-CPh L i (2.3a)  38  2.4.3 Preparation of 2 Mes(n—Bu)P-CPh L 1 (2.3b)  38  2.4.4 Preparation of Mes(Me)P—CPh H (2.4a) 2  38  2.4.5 Preparation of Mes(n-Bu)P.--CPh H (2.4b) 2  39  2.4.6 Synthesis of 2 Mes(Me)P—CPh M e (2.6a)  40  2.4.7 Preparation of CIP(NEt ) 2  40  2.4.8 Preparation of ) —P(NEt (2.7a) Mes(Me)P—CPh 2  41  2.4.9 Preparation of H —SiMe (2.8a) 2 Mes(Me)P—CPh  42  2.4.10 Preparation of Mes(Me)P—CPh 3 — 2 SiMe (2.9a)  42  2.4.11 X-ray Crystallography  43  2.5 References  45  Chapter 3 Anionic Oligomerization of Phosphaalkenes: Analysis by MALDI-TOF Mass Spectrometry* 3.1  Introduction  47 47  3.2 Results and Discussions  50 V  3.2.1 Preparation of oxidized oligomers from anionically initiated MesP=CPh 2 to form Me[(Mes)P(=O)-CPh ] 2 H, 3.9a 3.2.2 Origins of 3.1 0a  —  50  The “Second Distribution”  54  3.2.2.1 Decomposition due to Oxidation  54  3.2.2.2 Backbiting  57  3.2.2.2.1 Varying Reaction Conditions  58  3.2.2.2.2 Testing A Different Initiator: Preparing 2 n-Bu[(Mes)P(=O)-CPh ] H, 3.9gb  59  3.2.2.2.3 Testing Different Phosphaalkenes: Preparation of Me[(Mes)P(=O)-CPhAr]H, 3.15a and 3.26a  61  3.2.2.3 Fragmentation  67  3.3 Conclusion  67  3.4 Experimental  68  3.4.1 Materials and General Procedures  68  3.4.2 Preparation of 2 Me[MesP-CPh ] H, 3.8a  69  3.4.3 Preparation of 2 Me[MesP(=O)-CPh ] H, 3.9a  69  3.4.4 Preparation of 2 Bu[MesP(=O)-CPh ] H, 39gb  70  3.4.5 Preparation of 6 Me[MesP(=O)-CPh(p-C F 4 H )]H, 3.15a  70  3.4.6 Preparation of Me[MesP(=O)-CPh(p-C OMe)]H, 3.26a 4 H 5  71  3.5 References  72  Chapter4 The Coordination Chemistry of Poly(methylenephosphine)s with Tungsten, Molybdenum and Chromium  74  4.1 Introduction  74  4.2 Results and Discussion  76  4.2.1  Model Compound Reactions  76  vi  4.2.1.1  Coordination of Model Compound 4.4 to Tungsten  76  4.2.1.2  Coordination of Model Compound 4.4 to Molybdenum  79  4.2.1.3  Coordination of Model Compound 4.4 to Chromium  81  4.2.2  Thermal Stability of Poly(methylenephosphine) 4.2 in Solution  82  4.2.3  Preparation of Group 6 Metal-Containing Poly(methylenephosphine)s  83  4.2.3.1  Coordination of Poly(methylenephosphine) 4.2 to Tungsten  84  4.2.3.2  Coordination of Poly(methylenephosphine) 4.2 to Chromium  90  4.2.3.3  Coordination of Poly(methylenephosphine) 4.2 to Molybdenum  92  4.3  Conclusion  94  4.4  Experimental Section  94  4.4.1  General Methods and Instrumentation  94  4.4.2  General procedure for phosphine complexes  96  4.4.3  Preparation of (HCPh 5 ) 2 (Me)MesPW(CO) (4.5a)  96  4.4.4  )(Me)MesPMo(CO) (4.5b) 2 (HCPh Preparation of 5  97  4.4.5  )(Me)MesPCr(CO) (4.5c) 2 (HCPh Preparation of 5  97  4.4.6  Metallation of poly(methylenephosphine) 42 with M(CO) 6  98  4.4.7 X-ray Crystallography  98  4.5 References  100  Chapter 5 Macromolecular Complexation of Poly(methylenephosphine) to Gold(l): A Facile Route to Highly Metallated Polymers 5.1  102  Introduction  102  5.2 Results and Discussion  103  5.2.1 Coordination of Au(l)to model compound 5.3  vii  103  5.2.2 Coordination of GoId(l) to poly(methylenephosphine) to yield gold-containing polymer 5.5  106  5.3 Conclusion  108  5.4 Experimental  109  5.4.1 Materials and General Procedures  109  5.4.2 Synthesis of [Mes(Me)(CPh H)PAuCl] (5.4) 2  109  5.4.3 Synthesis of n-Bu(MesP(AuCl)CPh )H (5.5) 2  110  5.4.4 X-ray Crystallography  111  5.5 References  113  Chapter 6 Inorganic/Organic Hybrid GoId(l)-containing Micelles  115  6.1  Introduction  115  6.2  Results and Discussion  117  6.2.1  The preparation of PImbPMPn block-copolymers 6.9a and 6.9b  118  6.2.2  Coordination of block-copolymers to gold(l), 6.lOa and 6.lOb  120  6.2.3  Solution self-assembly of gold-containing block-copolymers Plmb(PMPAu)n .121  6.3  Conclusion  125  6.4  Experimental  126  6.4.1  Materials and General Procedures  126  6.4.2  Preparation of 6.9a (m  =  308, n  =  46)  127  6.4.3  Preparation of 6.9b (m  =  222, n  =  77)  128  6.4.4  Preparation of gold-containing 6.lOa  128  6.4.5  Preparation of gold-containing 6.lOb  129  VIII  6.5  References  .130  Chapter 7 Overall Conclusions and Future Work  132  7.1  Summary of Thesis Work  132  7.2  Future Work  135  7.2.1  Uses for model compounds of poly(methylenephosphine)  135  7.2.2  The preparation of polymer with high tungsten-content  135  7.2.3  Gold-containing micelles  136  7.3  Closing Remarks  136  7.4  References  137  ix  List of Tables Table 2.1  X-ray crystallographic data for 2.4a, 2.7a, 2.8a and 2.9a  44  Table 3.1  Selected MALDI-TOF MS data for oligomeric mixture 3.9a  53  Table 3.2  Selected MALDI-TOF MS data for oligomeric mixture 3.8a  56  Table 3.3  MALDI-TOF MS data for oligomeric mixture 3.8a with partially oxidized P atoms  57  Table 3.4  Selected MALDI-TOF MS data for oligomeric mixture 3.9b  61  Table 3.5  Selected MALDI-TOF MS data for oligomeric mixture 3.15a  64  Table 3.6  Selected MALDI-TOF MS data for oligomeric mixture 3.26a  66  Table 4.1  Studies on the Thermal Stability of Poly(methylenephosphine) 4.2 in Solution  83  Table 4.2  Summary of Conditions for the Thermal Reaction of Poly(methylenephosphine) 4.2 with W(CO) 6 to Form 4.7a  Table 4.3  85  Summary of Conditions for the Thermal Reaction of Poly(methylenephosphine) 4.2 with Cr(CO) 6 to Form 4.7c  Table 4.4  92  Summary of Conditions for the Thermal Reaction of Poly(methylenephosphine) 4.2 with Mo(CO) 6 to Form 4.7b  93  Table 4.5  Details of Crystal Structure Determinations of 4.5a and 4.5b  99  Table 5.1  Details of Crystal Structure Determinations of 5.4  x  112  List of Figures  Figure 1.1 Examples of Synthetic Routes to Acyclic Phosphaalkenes  2  Figure 1.2 Examples of Reactions of P=C Bonds that Parallel Reactions with C=C Bonds  3  Figure 1.3 The Three Steps of Anionic Addition Polymerization: Initiation, Propagation and Termination  4  Figure 1.4 Preparation of polysilanes 1.1 polysiloxanes 1.2 and polyphosphazenes 1.3  6  Figure 1.5  Reactivity of poly(methylenephosphine) 1.19  16  Figure 2.1  The solid-state molecular structure of 2.4a  31  Figure 2.2  The solid-state molecular structure of 2.7a  34  Figure 2.3  The solid-state molecular structure of 2.8a  35  Figure 2.4  The solid-state molecular structure of 2.9a  36  Figure 3.1  Mechanism of anionic polymerization (initiation, propagation and termination) for P=C bonds  48  Figure 3.2  MALDI-TOF MS of oligomer mixture, 3.9a  53  Figure 3.3  MALDI-TOF MS of oligomeric mixture 3.8a  56  Figure 3.4  Proposed Mechanism of Backbiting of Propagating Oligomer 3.7a at C  58  Figure 3.5  MALDI-TOF MS of n-BuLi initiated oligomer mixture, 3.9mb  61  Figure 3.6  MALDI-TOF MS of the oligomeric mixture 3.15a  64  xi  Figure 3.7  MALDI-TOF MS for oligomeric mixture 3.26a  66  Figure 4.1  H} NMR spectra (diglyme) of 4.4 and 4.5a 1 P{ 31  77  Figure 4.2  Molecular structure of the tungsten-model adduct 4.5a  79  Figure 4.3  Molecular structure of the molybdenum-model adduct 4.5b  81  Figure 4.4  P NMR Spectrum in 2 31 CI of: 4.2 and 4.7a CD  86  Figure 4.5  Infrared Spectra of Metal carbonyl complexes  87  Figure 4.6  X-ray photoelectron spectrum of tungsten-containing 4.7a  88  Figure 4.7  X-ray photoelectron spectrum of the P 2p binding energy of 4.2 and 4.7a  89  Figure 5.1  P NMR spectra of 5.3, 5.4, 5.2 and 5.5 31  104  Figure 5.2  The solid-state molecular structure of 5.4  106  Figure 5.3  TGA trace for gold-containing polymer 5.5  108  Figure 6.1  The solution self-assembly of an AB block-copolymer to form a macromolecular structure (shown: cross-section of a spherical micelle)  116  Figure 6.2  TEM images of 6.lOa  122  Figure 6.3  TEM images of 6.lOb  124  Figure 6.4  Sketches of two basic structural motifs for block-copolymers in dilute solution: (a) spherical micelles and (b) cylindrical micelles  xl’  125  List of Symbols and Abbreviations  abs. AD  absolute  =  Anno Domini  =  amu  atomic mass units  =  Anal. Ar  Analysis  =  Aryl  n-Bu  n-Butyl  t-Bu  tert-Butyl  °C  degree Celsius  Calcd cat.  Calculated catalytic  =  cf= confer, compare CPS d  day  =  dba Da  counts per second  =  Dibenzylideneacetone, (PhCHCH) C0 2  =  Dalton  =  DLS  Dynamic Light Scattering  =  Diglyme dn/dc EDX  =  =  E or E’ E  =  E El  Bis(2-methoxyethyl) ether, 3 CH C O 2 CH H  refractive index increment Energy dispersive X-ray spectroscopy Inorganic atom  =  electrophile Energy  =  Electron Impact  equiv Et  =  =  =  equivalent(s)  Ethyl  Formvar FTIR  =  =  polyvinyl formal, TEM grid support film  Fourier Transform Infrared  XIII  Glyme = 1 ,2-Dimethoxyethane, 3 H CH C O 2 CH GPC = Gel Permeation Chromatography h = hour ICP-MS = Inductively Coupled Plasma Mass Spectrometry IR = Infrared MALDI-TOF= Matrix-Assisted Laser Desorption/Ionization Time of Flight -  Me  Methyl  MeO  Methoxy  Mes = Mesityl = 2,4,6-trimethyiphenyl; 3 -2,4,6-Me 2 H 6 C Mes* = Supermesityl  2,4,6tBu 2 H 6 C 2,4,6-tri-tert-butylphenyl; 3  mm = minute M = Number average molecular weight = Weight average molecular weight mol  mole  MS = Mass Spectrometry NMR = Nuclear Magnetic Resonance PDI = Polydispersity Index Ph = Phenyl ‘Pr  isopropyl  PS = Polystyrene ref. = reference ret. = relative rt = Room temperature, 25 °C R, R’, or R” = Side group s = second SEM = Scanning Electron Microscopy Tor Temp. = Temperature Tonset = Onset temperature of weight loss TEM = Transmission Electron Microscopy TGA = Thermogravimetric Analysis xiv  THF  =  Tetrahydrofuran  TMS  =  chiorotrimethylsilyl, Si(CH ) 3  TMSCI  =  VAZO 88  wt%  chiorotrimethylsilane, (CH S1CI ) 3 =  1,1’-Azobis(cyclohexanecarbonitrile)  Weight percentage  xv  Acknowledgments  This seems an impossible task to thank everyone, but I’m going to try... First and foremost, a big thank you to Dr. Derek Gates for accepting me into the lab and providing advice and encouragement. Fellow Gates group members have made the lab a fun and interesting place to work: Dr. Chi Wing Tsang, Dr. Mandy Yam, Dr. Vince Wright, Kevin Noonan, Joshua Bates, Julien Dugal-Tessier, Cindy Chan, Paul Siu, Tom Hsieh, Yuen-Ying Carpenter, David Riendl, and Bastian Feldscher.  Thanks also to those who helped with the instruments for the characterization of stuff: Marshall Lapawa (MALDI-TOF), Dr. Yun Ling (MS), Mary Mager (EDX/SEM), the people at Wyatt (GPC), Dr. Johan Janzen (DLS), Garnet Martens and Derrick Home (TEM). Also, for the characterization that I did not perform myself: Ken Chung Wong (XPS), Josh Bates and Dr. Brian 0. Patrick (x-ray crystallography). Lots of people within the department were particularly helpful making my research possible and/or easier: John Ellis, Xin-Hua Huang, Brian Snapkauskas, Ken Love, and Brian Ditchburn.  I have to thank my friends from models night for their endless support and enthusiasm as well as affording some fabulous times. Each of my friends are inspirations to me in some form, for example: Ali Lee: incredibly insightful about pretty much everything, but in particular, people which makes for fabulous conversation; Louisa Stanlake: the funnest (that’s a word... found it in a dictionary once) person ever; Jennifer Kozak: so driven someone should give her nobel prize; Jackie Stewart: so much energy she makes the rest of us look like snails; Courtney Turner: even at such a young age, has a fabulous handle on who she is; Shiva Shoai: future diplomat for the world.  xvi  Other people in the chemistry department whose friendship over the years has been important and deserve a shout out: Tamara Kunz, Agostino Pietrangelo, Kristin Matkovich, Howie Jong, Paul Hurley, Bryan Shaw, Jason Thomas, Andrew Tait (and Natalie Ruhr), Jay Reid, Pavel Glaze, Timin Hadi, Mark Wood (and Kathleen Wood).  During grad school, I have been really lucky with very understanding friends: Roxan Maurcot (Hon’s anyone?), Karmin lp (heart heart everything), Dr. Rebecca Rivera, Scot Ramsay, Neil Anderson, Mike Shapcotte, Stuart Dean, and especially Dale Henshaw.  Most importantly, I have to thank my family for being so supportive: my parents, Lynn and Neil Gillon (some day you’ll get to retire and move in to the apartment); my favourite sister Carrie, despite the fact that she hates the polymer she was my best friend (and roommate for so long); my favourite brother Tristan, teacher of the language on the internets (roflmao, who knew...) and conspiracy theories.  xvii  Dedication  This thesis is dedicated to my parents who taught me the joys of reading and discovery. It was for them that I wrote the following paragraph; the only one in entire thesis that they would probably understand (and my favourite).  Phosphorus is an element. It has 15 protons, 15 electrons and 16 neutrons in its most abundant form. It exists in 3 allotropes that strangely come in 5 colours: red, white (or yellow) and black (or violet). Sometimes, as the white allotrope, it has no colour at all. In air, it will glow. Sometimes it’s pyrophoric (white), sometimes it’s not (red). It can be found in Group 15, though its chemistry is like that from group 14, sometimes. White phosphorus is always toxic. Though phosphorus is required by every cell in the human body for normal function; it is an essential 1 Naturally, it was first isolated from urine. An alchemist by the name of Hennig Brandt mineral. from Hamburg of the Holy Roman Empire failed to make gold. Nevertheless, he landed in the history books for his 1669 AD discovery of the element with the atomic number 15 and the symbol P.  It is a truth universally acknowledged, that a phosphorus atom in possession of a lone pair must be in want of a metal. Pride and Preiudice by Jane Austen, if she were a phosphorus chemist.  xviii  Statement of Co-authorship  The material reported in Chapter 2 was published in 2007. Bronwyn H. Gillon, Kevin J. T. Noonan, Bastian Feldscher, Jennifer M. Wissenz, Zhi Ming Kam, Tom Hsieh, Justin J. Kingsley, Joshua I. Bates, and Derek P. Gates, “Molecular studies of the initiation and termination steps of the anionic polymerization of P=C bonds,” Can. J. Chem. 2007, 85(12), 1045-1 052. The chapter was entirely written by me. Undergraduate researchers synthesized all the compounds; I directly supervised Tom Hsieh who synthesized Me[MesP-CPh ]H. I was 2 involved in the characterization of compounds n-Bu[MesP-CPh }H, 2 2 ]P(NEt Me[MesP-CPh , ) and 2 ]SiMe and 3 Me[MesP-CPh H ]SiMe 2 Me[MesP-CPh .  A portion of the material reported in Chapter 3 was published in 2004. Bronwyn H. Gillon, and Derek P. Gates, “Analysis of the products of the anionic oligomerisation of a phosphaalkene using MALDI-TOF mass spectrometry,” Chem. Commun. 2004, 1868—1 869. I wrote the chapter and performed all the syntheses and characterizations.  The results presented in Chapter 4 will be submitted for publication shortly. I performed all the syntheses and characterizations. Except for 5 H)PW(CO) which was 2 Me(Mes)(CPh prepared by Tom Hsieh, an undergraduate whom I supervised.  The material reported in Chapter 5 was published in 2008. Bronwyn H. Gillon, Brian 0. Patrick and Derek P. Gates, “Macromolecular Complexation of Poly(methylenephosphine) to Gold(l): A Facile Route to Highly Metallated Polymers,” Chem. Commun., 2008, 2161-2163. I wrote the chapter and performed all the syntheses and characterizations.  xix  A version of Chapter 6 will be submitted for publication in due course. I wrote the chapter. Kevin J. T. Noonan synthesized the copolymers. I performed the coordination reactions with gold. Together, we prepared the nanostructures and performed their characterization.  xx  1  Chapter 1  Introduction  1.1  Phosphorus  The question I find most difficult to answer; the one which always crops up sooner or later when the subject is mentioned, is, approximately: ‘But how on earth did you come to get yourself mixed up in a crazy affair like this, anyway?’ Web by John Wyndham  Since the discovery of phosphorus, phosphorus-containing chemicals are countless in 1 Common number and boundlessly useful: from organic synthesis to materials science to DNA. household materials containing phosphorus include: matches, toothpaste, fertilizers, pesticides and detergents. Phosphorus is sourced from the earth in the form of phosphate minerals, in the 2 Elemental phosphorus case of Nauru from its only natural resource: ancient guano deposits. ), being fairly reactive to water and oxygen, must be extracted from minerals (rock phosphate 4 (P , other useful chemicals, 4 or phosphorite) by heating with coke and sand (Scheme 1.1). From P like phosphorus trichloride, can be prepared (Scheme 1 .2). Due to its varied reactivity, acting either as an electrophile or a nucleophile depending on reaction conditions, PCI 3 is a useful commodity chemical and precursor to widely used chemicals like PCI , PPh 5 , BINAP and 3 countless others. A class of significant, albeit lesser-known, phosphorus-containing molecules known as phosphaalkenes, important to this thesis work, can also be prepared from PCI . 3  24 2 (P0 +6 Si0 3 Ca 2 )  +  10 C  1500°C  6 CaSiO 3  +  10 CO  +  4 p  Scheme 1.1  References start on page 21  Chapter 1  2 A  +6Cl 4 P 2  3 4PCI  Scheme 1.2  Phosphaalkenes, compounds with genuine (2p—3p)rr-bonds, are an intriguing class of low-coordinate phosphorus species due in part to their challenging synthesis. The first stable acyclic derivative was reported in the mid-I 970’s from a condensation reaction followed by a 5 Since then, other methods of 1 ,3-silatropic tautomerization (see Figure 1.1, Route A). preparation have been developed, including condensation reactions (Routes B  —  D), phospha  Wittig reactions (Route F), base-catalyzed elimination reactions (Route G), and base-catalyzed keto-enol type tautomerization reactions (Route H). Phosphaalkene synthesis via Route E requires the formation of a terminal metal-phosphinidene complex (see Figure 1.1).  R  Li  R—P’ ÷ O=C \ R” SiMe.  SiMe /R 3 + 0C \ \ Cl 3 SiMe  R—P  /  ClSiM\  R’  Base (cat) 2 CH  H’  Bas/ R  D_C ‘SR” X H  Figure 1.1  -LiOSiMe 1 Q 3  ,R’ P=C R R’  F Me t-Me  R  R’ H / / R—P\ + 0C R” H  Me  D Base -2HX  3 -O=PMe  R—P\ H  +  2 CR’R”X  NçMO  R’  R’ / R  PML  +  R”  +  R”  Examples of Synthetic Routes to Acyclic Phosphaalkenes.  References start on page 22  Chapter 1  3  Interest in phosphaalkenes continues to grow due to their parallels to the chemistry of 68 Phosphaalkenes can undergo reactions similar to C=C bonds and their potential applications. alkenes, some examples are shown in Figure 1.2. Like alkenes, phosphaalkenes undergo Diels Alder-type reactivity (reaction A) with butadiene resulting in the formation of a phosphorus heterocycle. Small molecules, like HX or H , add across the PC bond (reactions B and C, 2 respectively). Reaction D demonstrates the phosphorus analogue of an epoxide formation. Finally, P=C bonds can coordinate in an  2  fashion to metal centers like C=C bonds as shown in  reaction E. Incidentally, compounds with P=C bonds are being explored for their effectiveness 913 as well as in polymer science. 1421 as ligands in transition-metal catalyzed reactions,  [M] P=C  [O] PC  o  /  \  A  P—C-  [Rh]caV /X  H\ PC  Figure 1.2  X\  /H  PC_ or  Examples of Reactions of P=C Bonds that Parallel Reactions with C=C Bonds.  References start on page 22  Chapter 1  4  1.2 Polymers  Plastics, an array of polymerization products, are ubiquitous in a North American’s life. In fact, the plastics trade in Canada was worth over 15 billion dollars in 2007.22 Methods of preparing organic polymers are limited to just two methods: (1) step-wise or (2) chain growth polymerization. Step-wise polymerization requires that the monomers contain functional endgroups (for example: hydroxyl groups, carboxylic acids). The polymer is made by a series of condensation reactions eliminating a small molecule (commonly water). For addition polymerization, an unsaturated monomer (containing a C=C bond, for example) is required. The polymer is made by the addition of ions or radicals across the multiple bond of the monomer. Addition polymerization occurs in three stages: (1) initiation: the activation of a C=C  7t  bond to  generate an ion (heterolytic cleavage) or a free radical (homolytic cleavage); (2) propagation: the continual addition of monomer units which increase the length of the growing chain; and (3) termination, addition of a species such that it quenches the active site of the growing polymer. Figure 1.3 illustrates the mechanism of an anionic addition polymerization. •  Initiation:  R:e  •  .  /\  II  —ACC ,--/ / ‘ II II(  r Propagation.  I I  R—c—c:e  c=c  1/  R_C_Cj_.e  Ii  i R-Fc—c :e n+1  L  Termination:  Figure 1.3  Ii  El ii  ii  R4C—C—I--:e  IiL iiJm  m>n  R-l-C—C-l-E  IiL iiJm  The Three Steps of Anionic Addition Polymerization: Initiation, Propagation and Termination.  References start on page 22  5  Chapter 1  1.2.1  Inorganic Polymers Most research in polymer science is focused on organic polymers which possess carbon  atoms in the backbone. In contrast, the study of inorganic polymers is in a more primitive stage of development. Inorganic polymers contain at least one element other than C, 0 or N in the 23 The preparation of such polymers is challenging and continues to be an active area backbone. of research due to their unique properties and potential applications. Until recently, inorganic polymers were not synthesized using addition polymerization, a common method of preparing organic macromolecules. Addition polymerization requires a site of unsaturation (E=E’ or EE’ bonds), but unsaturated inorganic monomers that are suitable (stable and readily available) are 4 Therefore, inorganic polymers have historically been synthesized only by step-wise scarce. 2 ’ 23 or ring-opening methods. Some important inorganic polymers include polysilanes (1.1), polysiloxanes (1.2) and polyphosphazenes (1.3).  rRl  II I —f--Si--I-II I  [R] 1.1  1 II I -+-Si—O-+II I rR  [R  1.2  J,  rR  II II  —I-PN [R 1.3  There are multiple methods of synthesizing (each of) polymer 1.1, 1.2 and 13 (see Figure 1.4 for a few examples) most of which are based on polycondensation or ring-opening methods. Polysilanes 1.1 can be made through thermally induced Wurtz coupling of organodichlorosilanes in the presence of sodium metal. Organodichlorosilanes also act as precursors to polysiloxanes 1.2 when introduced to water. Polyphosphazenes 1.3 can be made 2327 by thermally induced ring-opening of hexachlorocyclotriphosphazene.  References start on page 22  Chapter 1  6 H-Si Na  R  1.1  Cl—Si—Cl R 0 2 H  Si—C [F!  —-  1.2 Cl  Cl  heat  N’N  ii Cl-..p Cl  i p  -  Cl  rci I —j—P=N Lcl I .3a  Figure 1.4  Preparation of polysilanes 1.1 polysiloxanes 1.2 and polyphosphazenes 1.3a  Each of these types of polymers has diverse properties and an array of applications. 28 Their properties are due to the different functionalities in the backbone and/or the side chains.  Polysilanes 1.1 have unique optical and electronic properties due to the delocaliztion of a electrons. Polysiloxanes 1.2 are commonly found in most, if not all, Canadian households. Their applications include sealants, lubricants, contact lenses and medical implants. Their unique properties, such as high flexibility (even at low temperatures) and high thermo-oxidative stability  are a consequence of the strong Si—C bonds in the backbone with long Si—C bonds (1.64 A vs 1.54 A for C—C bonds) and large Si—C—Si bond angles (—143° vs —109° for C—C—C bond  angles). The strong P—N bonds in the backbone (alternating P—N and P=N bonds) in polyphosphazenes 1.3 result in the material’s high temperature resistance and fire-retardancy.  The side chains in polyphosphazenes 1.3 are easily modified by way of simple nucleophilic substitution reactions of the chloride with other organic functionalities. As a result, the properties of 1.3 are tunable and allow for access to new materials with variable properties.  Polyphosphazenes have found applications as insulators, optical switches, lenses and  References start on page 22  Chapter 1  7  29 and belong to an important class of inorganic polymers with phosphorus atoms in elastomers the main chain. We are interested mainly in phosphorus-containing organic polymers.  1.2.2  Hybrid Phosphorus-Carbon Polymers  The incorporation of phosphorus into the polymer backbone is an emerging area of research which has often led to materials with novel properties. Importantly, phosphorus polymers are of interest for their specialty applications as electroluminescent devices, sensors, biomaterials, and catalyst supports. 23 27, 30 The difficulty in finding suitable methods to ’ 14 incorporate phosphorus atoms into long chains is a major challenge for researchers in this area  31-42  Some recent examples of phosphorus-containing polymers possessing interesting electronic properties are found in analogues of conjugated organic polymers. Some recent examples of such materials include a simple system developed by Lucht and coworkers. Through transition-metal mediated condensation polymerization of diiodobenzene derivatives with primary alkylphosphines, Lucht and coworkers were able to obtain conjugated polymers (j•4)•43’44  Hybrid polyaniline-poly-p-phenylene phosphine polymers (1.5) are prepared in a  similar fashion using Pd-catalyzed coupling reactions of primary phosphines and dihaloaromatic 45 Gates et a!. use the condensation polymerization method to obtain the first diamines. phosphorus analogue of poly(p-phenylenevinylene)s (PPV’s which are used in organic light emitting diodes) with moderate molecular weights (1.6 and  1.7)1617  Protasiewicz and  coworkers has shown that similar polymers (1.8) showed evidence of conjugation through analysis by UVNis spectroscopy. 47 A key challenge to the preparation of these types of ’ 46 macromolecules involves their low solubilities which often results in low molecular weight polymers. So far, these polymers have not been used in devices.  References start on page 22  Chapter 1  8  PPv  ±°if  R  1 A!  1.4  1.5  3 OSiMe  \ 3 OSiMe 1.6  ]  n  n 1.7  n-Hex  n  1.8  In contrast to the above examples, polymers containing phospholes in the backbone have been recently incorporated into electroluminescent devices. Réau and coworkers have integrated phospholes into poly(thiophene)s (1.9). The material, prepared by electropolymerization, has been demonstrated as a detector of Group 16 elements. 4849 Also, fused-ring phosphole-containing poly(thiophene)s (1.10) have been prepared which showed  References start on page 22  Chapter 1  9  5051 Recently, by extending photoluminescence properties both in solution and in the solid-state. the conjugation of similar frameworks (1.11), the emission colours of the material can be tuned 52 Finally, materials incorporating phospholes into conjugated organic from green to yellow. 53 ’ 33 backbones have been prepared (1.12) with modest molecular weights.  1.9  1.10  1.11  1.12 Spacer F  =  13 H 6 C  F  13 H 6 0C  -  -*  13 H 0 6 C  Macromolecules with phosphines in the backbone are also known. For example, the first poly(vinylenephosphine) has been recently reported. The synthesis of 1.13 involves the radical copolymerization of cyclooligophosphines with phenylacetylene resulting in a yellow solid that fluoresces blue-green (see Scheme 1  3)32  With polymers containing chiral P atoms in the  backbone, Chujo and coworkers set out to form optically active polymers like 1.14 and  References start on page 22  Chapter 1 56  10  Using an interesting strategy of anionic ring-opening polymerization of a phosphirene 1.16,  Vanderark et al. demonstrates a facile route to poly(vinylenephosphine)s 1.17 (see Scheme j•4)34  \  P—P  I  /  \  H  rI / —f—C=C  radical +  Ph  I  initiator  P  I  L  M 1.13  Scheme 1.3  Cl. 3 BH  3 BH 1.14  1.15  n  A  Me  1/n n-BuLi Me  n-Bu  1 rph  _f )ç4f Ph  Ph  P  [Me  M[  1 Me  ?==••-%%[ H _jn  1.16  m+n=1 n 0.35  =  1.17  Scheme 1.4  Incorporation of phosphorus atoms into the polymer backbone is obviously an active area of research. The recent examples above were meant to highlight the strategies used by other researchers (condensation, ring-opening, and electro- polymerizations). Previously, References start on page 22  Chapter 1  11  addition polymerization was often dismissed as unsuitable for inorganic systems despite the numerous advantages of addition polymerization over step-wise methods. For example, condensation polymerization requires very accurate stoichiometry and high monomer purity in order to gain high molecular weight polymers. Also, condensation reactions by their nature eliminate wasteful byproducts that are often toxic (e.g. HCI). The disadvantage in using ringopening polymerizations can be the lack of control over the resulting polymer’s molecular weight. The Gates group is tackling these problems by developing the addition polymerization of 18 phosphaalkenes (PA) to afford phosphorus-carbon hybrid homo- or co-polymers.  1.3  19,21,57  History of PoIy(methylenephosphine)s  The Gates group set out to prepare inorganic macromolecules through addition polymerization. Several multiple-bond systems were considered as potential monomers; however, P=C bonds were targeted due to their analogous reactivity to CC bonds. 6758 For the first time, an inorganic polymer was synthesized through addition polymerization methods.  The polymerization of phosphaalkene 1.18 affords poly(methylenephosphine) 1.19; a new functional phosphine polymer with alternating phosphorus and carbon atoms in the main 19 lniflal studies suggested that the polymerization of phosphaalkene 1.18 requires high chain. temperatures (> 150 °C), long reaction times, and high concentrations, even in the presence of radical or anionic initiators. Estimated Ma’s of up to 11 500 g mo1 1 (vs polystyrene) have been reported. Functionalization of the polymer 1.18 is achieved through reactions with H 0 and 2 elemental sulfur resulting in oxidized polymer 1.20 and sulfurized 1.21, respectively.  References start on page 22  12  Chapter 1  F I  Phi I  o  II  t-P-C  [Mes Ph Ph \  / Mes  Ph  Radical or Anionic Initiator >150°C  1.20  J..l-J_ I I I I  LMeS  Ph]  S  Phi  1.19  1.18  IL Mes  Ph  I  .Jfl  1.21  Notably, characterization of the phosphine polymer 1.19 by GPC (gel permeation chromatography) proved confusing. Our laboratory, at the time, was equipped with a traditional GPC system that required column calibration with polystyrene standards. Consequently, the estimated Me’s of the polymers were artificially diminished as determined by GPC. With a triple detection GPC (equipped with a laser light scattering detector), the absolute Me’s of polymers  were determined and were greater than the estimated Me’s. For example, sulfurized polymer 1 and an absolute M of 32 000 g mo1 . This nearly 1 1.21, had an estimated M of 11 900 g mor threefold difference in the determined molecular weights can be rationalized due to the  , as described in the next 2 molecular weight difference between styrene and MesP=CPh paragraph.  The principle behind GPC is that macromolecules are separated based on their volume (or size). 59 Typically, polystyrene (1.22) standards of known Me’s are used to create a calibration curve (M vs elution time). However, there is an inherent problem when analyzing a sample that is chemically different than the standards used to calibrate the column. To illustrate this problem, consider a sample of polystyrene 1.22 and a sample of poly(methylenephosphine) 1.19 each with 100 repeat units. Both samples have approximately the same length and accordingly, approximately the same volume. As a result, both samples have the same elution time. Consequently, a GPC that has been calibrated with polystyrene samples would estimate that the phosphorus-containing 1.19 (n  =  100) sample has similar molecular weight to that of the  polystyrene. However, with 100 repeat units, the molecular weight for organic 1.22 is 10 400 g References start on page 22  Chapter 1  13  . Therefore, polystyrene 1 1 but for inorganic 1.19 is three times greater at 31 600 g mol mol makes a poor standard for poly(methylenephosphine)s. Since the Gates group was only equipped with a traditional GPC, we looked for other methods to characterize the absolute Me’s of the phosphorus-containing polymer 1.19. Fortunately, the Chemistry Department at the University of British Columbia possesses an accessible MALDI-TOF MS. We are interested in analyzing poly(methylenephosphine)s by MALDI-TOF MS because it gives absolute masses rather than relative ones (eg. GPC) and usually only molecular ions are observed without fragmentation.  f-c-c  [  H  Ph  1.22  The emergence of soft ionization (i.e. MALDI) mass spectrometric techniques to investigate high molecular weight (MW) macromolecules is revolutionizing the field of synthetic 6062 however their use is still relatively uncommon in the analysis of inorganic polymers, 6367 A notable advantage in using MALDI-TOF MS to characterize polymers is the systems. detection of the endgroups. Our group had not been able to spectroscopically identify the endgroups of poly(methylenephosphine)s. Numerous attempts were made to detect phosphorus-containing 1.19 by MALDI-TOF MS, but to no avail. Often, smaller chains are easier to ionize. In fact, Tsang et a!. had previously shown that phosphaalkene 1.23 was oligomerizable with a substoichiometric amount of HOTf (see Scheme 1.5). Importantly, the ions of the resulting oligomers 1.24 were detected up to 6 repeat units using electrospray mass 68 spectrometry.  References start on page 22  14  Chapter 1 H /  \  Mes*  1.23  1/3HOTf  F  ‘j  1  OTf-l---P—C—IH  P=C  H  Mes*=  Ill  IL Mes’  H  fl  1.24  Scheme 1.5  Another question that must be addressed is whether the initiation, propagation, and termination steps for the addition polymerization of PC bonds are analogous to those known for olefins (recall Figure 1 .3). Analysis of more easily characterized small molecules that are model compounds to homopolymer 1.19 provides invaluable insight into the mechanism of polymerization.  Initially, polymerization studies of P=C bonds were focused on radical initiation methods. In fact, with a free-radical source (VAZO), the copolymerization of styrene with phosphaalkene 1.18 was investigated primarily by Dr. Mandy Yam and Dr. Chi Wing Tsang (see Scheme 1.6). The resulting random copolymers 1.25 represent new hybrid inorganic-organic macromolecules that can be used in polymer-supported catalysis. Specifically, copolymer 1.25 has been used in Suzuki cross-coupling reactions that form a C-C bond between aryl halides and aryl-boronic acids (refer to Scheme 1.7). The coupling occurs in the presence of a palladium catalyst 4 and a base. Phosphine ligands are used because they are stable and ) 3 (commonly Pd(PPh they readily complexed to the Pd in its active zero-valent form. It has been found that copolymer 1.25 is a better ligand than homopolymer 1.19 since the product yield is much greater (90% cf 23%). Without the presence of phosphorus-containing 1.25 (or any other phosphine), the product yield is poor. These results suggest that in fact, the copolymer 1.25 is acting like a molecular phosphine, though there has been no conclusive evidence that it coordinates to palladium.  References start on page 22  Chapter 1  15 H Ph  2  VAZO  Ph  Mel  Ph  H H  Sh]\  1.25  ] m E]  Scheme 1.6  B(0H)2 +  1.5 THE Scheme 1.7  The use of the copolymer 1.25 as a ligand in catalytic reactions showed that the polymer can behave chemically like a phosphine. Investigations into the chemical functionality of poly(methylenphosphine)s 1.19 began with simple reactions like oxidation and sulfurization in order to stabilize the polymer to air (see Figure 1.5).19 Since that initial report, polymer 1.19 has been shown to form adducts with borane (resulting in boronated I  Additionally, treatment  of 1.19 with MeOTf affords methylphosphonium ionomers 1.27.69 Interestingly, only —50% of the phosphines in the backbone can be methylated. Interestingly, when I started this thesis work, homopolymer 1.19 had never been coordinated to a metal system.  References start on page 22  16  Chapter 1  FoII  B 3 FH  Phi I  Phi I  :  S8  F  [Ms hj  -  1.19  S  *..  Phi  III II +-P—c—+ liii [Mes Ph]  n  1.21  OTf Me Ph  1+1 P—c II  Ph ..  ‘  Mes Ph  \  P—c II  Mes Ph  x x  =  0.5, y  y =  “  0.5  1.27  Figure 1.5  Reactivity of poly(methylenephosphine) 1.19.  After radical methods were developed, the next logical step in the investigation of the polymerization of P=C bonds is the extension to anionic living methods. Living polymerization enables the preparation of macromolecules with controlled architectures (complex structures such as block copolymers, star polymers, and comb polymers). 7073 Swarc first demonstrated in 1956 that adding styrene to a mixture of an alkali metal and naphthalene in THE results in an increase in the viscosity of the reaction mixture. However, this increase in viscosity ceases eventually, but upon addition of more monomer, the viscosity increases again. This first example of living polymerization illustrates that the living chain can rest indefinitely. Only upon controlled addition of an electrophile is the polymer terminated. The result is that the prepared polymers have a narrow range of lengths with low polydispersity indices (1.00  <  PDI <1 .10)  because the polymer chains grow without termination (versus traditional addition polymerization). Over the past 60 years, living polymerization has evolved to include other types of systems: anionic, cationic, ring-opening and free radical. 7377  References start on page 22  Chapter 1  17  Block polymers possess two or more chemically different polymer segments, or blocks, connected by a covalent linkage. Notably, it has been recently found that living polymerization methods have been used to obtain block copolymers containing the three main classes of inorganic polymers (polysilanes 1.1, polysiloxanes 1.2, and polyphosphazenes 1.3). Saam et al. 78 By using were the first to successfully polymerize inorganic monomers in a living fashion. anionic ring-opening polymerization methods, they have provided routes to block copolymers, polystyrene-b-polydimethylsiloxane 1.28. More recently, the first copolymer containing 79 Poly(ethyleneoxide) polysilane blocks (1.29) have been prepared by Sakurai and coworkers. b-polyphosphazene 1.30 represent the expansion of the range of functional inorganic blocks.  H H  Si—C—I-H  n-Bu-I—C—C  Ill  [  1  Me  I  I  Me n-Bu--j--Si—Si  ]  H Ph m Me  C—C  II  III  [  Me Me  m  H  H  Me 2 CO  1.29  1.28 CCHCF  CF 2 QCH 3  C 3 CF — 1 O 2 P--N H  [  PN  CHCHOCH m  H  CF 2 OCH 3  1.30  Recently, living polymerization was achieved for MesP=CPh 2 using substoichiometric ° Studying the polymerization at various temperatures, Kevin Noonan of 188 amounts of n-BuLi. the Gates group has been able to estimate the activation energy for the propagation of P=C bonds in glyme (Ea = 14.0 ± 0.9 kcal mol-1). ° Importantly, homopolymers with controlled 8 molecular weights are now readily prepared as well as block copolymers 1.31 of styrene and phosphaalkene. More complex architectures containing poly(methylenephosphine)s are within reach.  References start on page 22  Chapter 1  18 Phi P—C-+H  n-Bu-f-—C--C  I  III  [  II  H Ph m Mes PhJ 1.31  1.4 Inorganic Micelles  Complex architectures can result from block copolymers which can self-assemble into mesophases with periodic order with typical repeating distances in the 10-200 nm range both in solutions or melts. 81 Vanzo was the first to observe morphological structures in block polymers. He showed that when solutions of diblock polymers (polystyrene-b-polybutadiene 1.32) are 82 Using an electron microscope, Vanzo observed evaporated, lamellar structures are formed. that the spacings corresponded to the dimensions of the randomly coiled blocks. Tuning external conditions such as pH or temperature or solvent can control the solution self-assembly of the different phases. The ability to control the order of the phases makes block copolymers compelling candidates for the building blocks of novel materials such as micelles, rods, and vesicles, for example. 83 Applications for these materials include growth of nanowires, nanoscale architectures for ceramics, and drug delivery.  1  EHH  PB—j-H  n-Bu--j---C—C  Lhm  in  1.32  PB=  H HH C. ‘/C C HHHI  H ..s  H CH  ?CF HH  H  I  H C. H’ H  References start on page 22  Chapter 1  19  Since Vanzo’s first discovery of the solution self-assembly of organic block copolymers, work has been extended to inorganic systems which could result in new structures with novel 85 Examples of organic-inorganic diblock copolymers that form micellar structures in properties. solution are rare. 86 The first example of the solution self-assembly of polymers with an inorganic block has been reported by Saam et al. who observed that poly(styrene-b-dimethylsiloxane) 1.33 “copolymers resemble surfactants due to the extreme differences in solubility between the  two blocks.” In cyclohexane, a good solvent for polysiloxanes, the formation of micelles occurs. In fact, at high concentrations of the colourless polymer in the aliphatic solvent, the solution turns blue. Winnik, Manners, and co-workers have reported that poly(ferrocenyldimethylsilane b-isoprene) 1.34 can form rigid cylindrical micelles. 8789 The length of these cylindrical micelles can be increased through the addition of more block copolymer that is dissolved in a good solvent for both blocks. The result is the controlled growth of the micelles. ° Cylindrical micelles 9 are formed from aqueous solutions of poly(ferrocenyldimethylsilane-b-[2-(N,Ndimethylamino)ethylmethacrylate]) 1.35, however, only moderate molecular weights have been 91 Redox-active micelles of poly(ferrocenyldimethylsilane-b-2-vinylpyridine) 1.36 have achieved. also been formed in 92 alcohols. 9 ’ 3 Simply by using different alcoholic solvents the morphology of the self-assembled structures can be formed as either spherical or cylindrical micelles.  ri I I  EMe 1 I Ii I Si—O-l-H n-Bu1-_b—C I I ‘Me [HPhjm 1 rHH  P1  =  —_:j.’  sec-Bu I P1 I I I  I  L  1.33  I  -‘60%  Jm  —30%  —10%  1.34  n-Bu n 1.35  1.36  References start on page 22  Chapter 1  20  Micelles (or other complex architectures) are formed in solution when the solubilities of the two blocks are different. In the case of block copolymer 1.31 from styrene and phosphaalkene, both blocks are soluble in polar aprotic solvents and insoluble in non-polar aliphatic solvents. Therefore, in order to induce self-assembly of phosphalkene-derived copolymers, an organic block that is soluble in non-polar aliphatic solvents could be selected.  1.5 Outline of Thesis  When I joined the Gates Group in 2002, P=C bonds had been successfully polymerized 94 The resulting for the first time through both anionic and radical methods. poly(methylenephosphine)s were characterized mainly by GPC and NMR spectroscopy. Some questions remained about these novel phosphorus-containing polymers. We wanted to gain insight into the structure of the polymer, particularly when anionically initiated. More specifically, we were interested in the site of initiation, the nature of the endgroups, and the mechanism of polymerization. With the polymer in hand, we also wanted to functionalize poly(methylenephosphine) at the P atom with transition metals.  Chapters 2 and 3 highlight our endeavors to get a handle on the mechanism of polymerization. In Chapter 2, the site of addition of the anion (R) at the P=C bond and the subsequent addition of an electrophile (e.g. H, Me) will be experimentally determined. These model compounds give invaluable information on the structure of the novel polymer 1.19. Chapter 3 deals with the preparation of oligo(methylenephosphine)s. These short-chained oligomers were mainly characterized using MALDI-TOF MS.  In Chapter 4, I switch gears  somewhat and describe the metallation of poly(methylenephosphine) using classical coordination chemistry with group 6 metal carbonyl complexes. Once metal incorporation was References start on page 22  Chapter 1  21  shown to be possible as a proof of principle, a more valuable metal system was investigated. Complexation of the polymer and its model compound to Au(l) is described in Chapter 5. Chapter 6 deals with utilizing the straightforward functionalization of poly(methylenephosphine)s with Au(l). Therein, we report the preparation of block-copolymers, polyisoprene-b poly(methylenephosphine)s, their coordination to gold and their solution self-assembled macromolecular structures. Finally, Chapter 7 concludes the findings of this thesis and proposes some future directions for this research.  References start on page 22  Chapter 1 1.6  22  References  1. J. Emsley, The shocking histoiy of phosphorus a biography of the devThs element. Pan: London, 2001. 2. Republic of Nauru: Permanent Mission to the United Nations. http://www. un. int/nauru/overview. html 3. F. A. Cotton, G. Wilkinson, Advanced Inorganic Chemistiy. 5th ed.; John Wiley & Sons: Toronto, 1988; p 386.  4. J. Emsley, D. 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References start on page 22  27  Chapter 2  Molecular Studies of the Initiation and Termination Steps of the Anionic Polymerization of PC bonds*  2.1  Introduction  Five years ago, our group reported the polymerization of phosphaalkene 2.1 to afford poly(methylenephosphine) 2.2; a new functional phosphine polymer with alternating phosphorus and carbon atoms in the main chain (see Scheme 2.1).1 Our initial studies suggested that the polymerization of 2.1 required high temperatures (> 150 °C), long reaction times, and high concentrations, even in the presence of radical or anionic initiators. It was subsequently shown that short-chain oligomers could be obtained when 2.1 was treated with anionic initiators (e.g. MeLi) in THF solution at ambient temperature. 2 The oligomerization of phosphaalkenes is further discussed in Chapter 3. This solution oligomerization has now been extended to the living anionic polymerization of monomer 2.1 to afford homopolymer 2.2 and block copolymers with controllable architectures. 3 In order to further develop the living anionic polymerization of P=C bonds and to prepare end-functionalized polymers it is necessary to understand fully the mechanism of anionic chain growth for 2.1. Ph /  / Mes  P=C \  Radical or Anionic Initiator  Ph  F I  Phi ..  4—P—c I I I [Mes Ph 2.2  2.1  Scheme 2.1  A version of this chapter has been published. Bronwyn H. Gillon, Kevin J.T. Noonan, Bastian Feldscher, Jennifer M. Wissenz, Zhi Ming Kam, Tom Hsieh, Justin J. Kingsley, Joshua I. Bates, and Derek P. Gates, “Molecular studies of the initiation and termination steps of the anionic polymerization of P=C bonds,” Can. J. Chem. 2007, 85(12), 1045-1052. Copyright 2007 NRC Canada. *  Chapter 2  28  To our knowledge, there is little previous work on the reaction of P=C bonds with typical anionic initiators. Of particular relevance to our studies is the synthesis of phosphine oxide 25a from phosphaalkene 2.1. Specifically, treating 2.1 with MeLi followed by MeOH and air oxidation afforded 2.5a. Both the carbanion (2.3a) and the phosphine (2.4a) were the presumed intermediates in this reaction, however, no characterization data for these species were reported. In a separate study, the addition of MeLi to RP=C(SiMe 2 (R ) 3  =  Mes, t-Bu)  afforded Li[MeRPC(SiMe ] which was characterized spectroscopically. 2 ) 3 57 In several other studies, the addition of alkyllithium reagents across the P=C bond in phosphinines and triphosphafulvenes similarly afforded only the P-alkyl products. 812 These regioselective additions are consistent with the predicted polarity of the P=C bond based on the electronegativities of phosphorus (ô+) and carbon (ô—). Interestingly, alkyllithium reagents can also react with phosphaalkenes with preservation of the P=C bond. 1316  In this chapter, the molecular model studies of the initiation and termination steps of the anionic polymerization of 2.1 are discussed. Two initiators were chosen for the present studies: MeLi and n-BuLi. Although n-BuLi is a better initiator for the anionic polymerization of 2.1  ,  MeLi is optimal in molecular model studies since the small Me-substituent is more likely to afford crystalline products. The new compounds obtained may be utilized as molecular models for the development of the coordination chemistry of polymer 2.2. Moreover, the development of methods to functionalize the endgroups in poly(methylenephosphine)s will afford telechelic polymers which may function as precursors to novel block copolymers.  References start on page 45  29  Chapter 2  2.2  Preparation of Model Compounds  F  Ph / P=C \ / Mes Ph  Rj-P-C4H  IL Mes Ph I  Mes Ph R R  L/  = =  I  I  R R  = =  Me 2.4a n-Bu 2.4b  2. MeOH -LiOMe  Me 2.3a n-Bu 2.3b  Mel  )>’..qe 2 \clP(NEt R ’SiCl  L/  \LiCl  Ph  Mes Ph  -Lid  Ph  R—P—C—Me  I  I  Mes Ph R  =  I  In  A(n-1)1  RPC:eeLi  0 or,/ 2 H  Ph  2.2  2.lN  R—P—C—H  Phj  Me 2.6a  I..  R—P—C—P—NEt 2 I I Mes Ph NEt 2 R  =  Me 2.7a  PhMe ..  II  R—P—C—Si—R I I I Mes Ph Me R = Me; R = H 2.8a R=R=Me 2.9a  HO or ‘air O  II  Ph  I  R—P—C—H  I  I  Mes Ph R = Me 2.5a  Scheme 2.2  2.2.1  General Preparation of Carbanions Li[Mes(R)P—CPh ] (2.3a, R 2  =  Me; 2.3b, R  =  Bu) A pale yellow solution of phosphaalkene 2.1 (prepared according to literature 17 methods)  18  in THF was treated with a slight excess of alkyllithium at low temperatures,  resulting in an immediate colour change to deep red. Analysis of the reaction mixture using 31 H 1 P{ } NMR spectroscopy confirmed the complete conversion of 2.1 to the carbanion 2.3a (ö  References start on page 45  Chapter 2  30  -44.3) orto 2.3b (ô = -31.1). These intermediates are believed to be related to the active species in the anionic polymerization of 2.1 (see Scheme 2.2)  2.2.2  Preparation of Mes(Me)P—CPh H (2Aa) 2 Carbanion 2.3a was quenched by addition of water or methanol to afford model  compound 2.4a MS (M, m/z  =  (ô31p =  —24.0). Additionally, 13 H}, 1 1 C{ H NMR spectroscopy and low resolution El  332) were consistent with the proposed structure (see Scheme 2.2). The 1 H  NMR spectrum of 2.4a shows a notably downfield doublet resonance at ô  =  4.87  JHp = 2 (  5 Hz)  which is assigned to the benzylic proton. Importantly, a doublet resonance is observed in the alkyl region (ó  =  1 .31,  JHP = 2  6 Hz) which is attributed to the P-CH 3 protons. Clearly, the addition  of the methyl anion occurred regioselectively at the phosphorus atom of the P=C bond. Also found in the alkyl region are sharp singlets at 2.52 and 2.21 ppm that are assigned to the ortho and para-methyl protons of the mesityl group, respectively.  Clear, colourless crystals suitable for X-ray diffraction were obtained from the slow evaporation of a concentrated solution of 2.4a in hexanes. The solid-state molecular structure and the crystallographic data appear in Figure 2.1 and Table 2.1, respectively. The solid-state molecular structure provides insight into the steric nature of the substituents around the P atom. Importantly, the cone angle of model compound 2.4a was estimated to be roughly 140° which is comparable to that of triphenyiphosphine (1450).19 The ligand cone angle 9 was estimated according to Tolman’s method for an unsymmetrical phosphine (PR 1R ) ligand. The cone 3 2 angle is the apex angle of a cylindrical cone centrally positioned 2.28 A away from the P. The edges of the cylindrical cone encompassed the van der Waals radii of the outermost atoms on each substituent on P. Using X-ray crystallographic data for 2.4a, 9 was estimated to be ca. 140°. The P—C bond lengths (A) fall into the typical range for P—C single bonds [P(1)—C(1) 1.852(1); P(1)—C(10) 1.840(2); P(1)—C(11)  =  =  1.882(1)1.20 Presumably, steric repulsion is References start on page 45  Chapter 2  31  responsible for the slight elongation of P(1)—C(11). For comparison, related P—C bonds where the carbon atom has two aryl substituents (i.e. 2 RArP—CHPh are ca. 1 .90 A in length. ) 21  22  C21  Cl 0  Figure 2.1 The solid-state molecular structure of 2.4a (50% probability ellipsoids). Hydrogen atoms are omitted for clarity. Selected bond lengths (A): P(1 )—C(1) = 1.852(1); P(1)—C(1 0) = 1.840(2); P(1)—C(11) = 1.882(1). Selected bond angles (°): C(10)—P(1)—C(1) = 107.34(7); C(1 0)—P(1)—C(1 1) = 100.51(7): C(1)—P(1)--C(1 1) = 100.18(6).  2.2.3  H (2.4b) 2 Preparation of Mes(n-Bu)P—CPh Using n-BuLi as the initiator for 2.1, the related compound 2.4b, was prepared by  terminating carbanion 2.3b with water, Scheme 2.2. Again, the reaction was quantitative as suggested by 31 H} NMR spectroscopy (ô 1 P{  =  —12.4). Upon workup, analytically pure 2.4b was  isolated in good yield (85 %) as a yellow oil. Akin to the Me-initiated 2.4a, the 1 H NMR spectrum of n-Bu-initiated 2.4b showed a characteristic doublet resonance at 4.91 ppm  JHp = 2 (  5 Hz)  which is assigned to the benzylic proton. A sharp singlet at 2.20 ppm is assigned to the para methyl mesityl protons. In contrast to the sharp signals observed for Z4a, the ortho-methyl mesityl protons in 2.4b gives rise to a broad signal centered at 2.56 ppm. The broadening may be a consequence of restricted rotation about the P-C (ipso-mesityl) bond. Additionally, there is considerable broadening of the resonance assigned to the ortho-methyl mesityl carbon (ô  =  23.8) in the 13 C{’H} NMR spectrum. Another interesting feature in the 1 H NMR spectrum of 2.4b involves the diastereotopic protons adjacent to the stereogenic phosphorus atom. In particular,  References start on page 45  Chapter 2  32  they give rise to two sets of multiplets (ö  =  2.02 and 1.55). Assignments were made with the  help of 1 H- COSY, HMQC, and HMBC experiments. H  2.2.4  Me (2.6a) 2 Preparation of Mes(Me)P—CPh With the purpose of modelling the functionalization of the endgroups of polymer 2.2, the  termination of the methyl-initiated species 2.3a with different electrophiles is investigated. These end-functionalized products are envisaged as model systems for the heretofore-unknown telechelic polymers.  In order to obtain Me-terminated 2.6a, carbanion 2.3a was quenched with neat methyl iodide, affording an orange solution  (ö31p =  —  13.5) (see Scheme 2.2). Model compound 2.6a  H, 13 H}, 31 1 C{ P NMR spectroscopy and low resolution El MS (M, m/z was characterized by 1  =  346). Although analytically pure material could not be isolated, analysis by NMR spectroscopy suggests 95% or higher purity from other phosphorus-containing compounds. As with butyl initiated 2.4b, the signal assigned to the ortho-methyl mesityl protons in the 1 H NMR spectrum =  1.87) is broad. Two doublets are observed in the alkyl region (1.70 ppm,  ppm,  JPH = 3  JpH = 2  13Hz; 1.39  7 Hz). The resonance with the larger P-H coupling constant is assigned to the P  3 group whilst the other signal is attributed to the quenching methyl group. CH  2.2.5  —P(N Et 2 ) (2.7a) 2 Preparation of Mes(Me)P—CPh Phosphine end-functionalized 2.7a was prepared by quenching 2.3a with a solution of  ) (1.1 equiv) in THF (see Scheme 2.2). The crude diphosphine was purified by 2 CIP(NEt washing the solid with cold hexanes  (— 78  °C). As expected, the 31 H} NMR spectrum of the 1 P{  product showed that the phosphorus atoms are inequivalent and give rise to two doublets (P2: 8 =  105.3; P1: 8  =  —9.4; 2 J,  =  205 Hz). The observed coupling constant is considerably larger  than in a related asymmetric diphosphine 4 P(NC [Ph P , 2 ) H CH  Jpp = 2  147 Hz] 23 and suggests  References start on page 45  Chapter 2  33  some direct P-P interaction (vide infra). In contrast to the broadened signals observed in the spectra for 2.4b and 2.6a, the resonances due to the ortho-methyl mesityl groups in 2.7a are inequivalent in both the 1 H and 13 H} NMR spectra. Presumably, this results from restricted 1 C{ rotation due to the increased steric bulk in 2.7a.  X-ray quality crystals of 2.7a were grown from toluene. Metrical parameters and crystallographic data are shown in Figure 2.2 and Table 2.1, respectively. Interestingly, the P(1 )—C(1 1 )—P(2) bond angle (99.17(9)  0)  is more acute than a typical sp 3 hybridized C atom.  This small bond angle combined with the short PP distance [P(1)—P(2) =  2.966(1) A; cf.  =  rVdW  3.7 Al may account for the large coupling constant ( Jpp) observed in solution. To confirm that 2  the structure observed in solution is the same as that in the solid state, a solid state 31 P NMR spectrum was recorded which revealed a similarly large coupling constant ( Jpp 2  =  255 Hz).  Surprisingly, both nitrogen atoms are planar with the sum of the bond angles at nitrogen totaling 3600.  Likely, the planarity is due to donation of nitrogen electron density into P(2) and this notion  is reinforced by the short P—N distances; P(2)—N(1)  =  1.678(2) and P(2)—N(2)  related bis(amino)phosphines, the P—N bonds are often shortened to 1.6  —  =  1.689(2) A. 24 In  1.7 A which is  accompanied by planarity at nitrogen. 2528 Also, the addition of the functional end-group results in the lengthening of the backbone P—C bonds to beyond typical single bonds [P(1 )—C(1 1) 1.942(2) and P(2)—C(1 1)  =  =  1.951(2) A]. 24  References start on page 45  Chapter 2  34 08 04  C29  G3 7 C  -  028  05  ci P1  P2  C25  N2 -.,  C24  09  Ni  019  017  010  020  012 016 015,-  -t 3 c 030  026  5)C27  cia 023  -C21  :014 022  Figure 2.2 The solid-state molecular structure of 2.7a (50% probability ellipsoids). Hydrogen atoms are omitted for clarity. Selected bond lengths (A): P(1)—C(1) = 1.851 (2); P(1)—C(10) = 1.843(2); P(1)—C(11) = 1.942(2); P(2)—C(11) = 1.951(2); P(2)—N(1) = 1.678(2); P(2)—N(2) = 1.689(2); P(1)P(2) = 2.966(1). Selected bond angles (°): C(1)—P(1)—C(10) = 105.1(1); C(1)— P(1)—C(11) = 110.05(9); C(10)—P(1)—C(11) = 101.5(1); P(1)—C(11)—P(2) = 99.17(9); C(11)— P(2)—N(1) = 103.87(8); C(11)—P(2)—N(2) = 105.97(9); N(1)—P(2)—N(2) 107.80(9); angles about N(1) atom = 359.7(3)°; angles about N(2) atom = 359.4(3)°.  2.2.6  Preparation of 2 --SiMe (2.9a) 2 Mes(Me)P—CPh —SiMe (2.8a) and 3 Mes(Me)P—CPh H Addition of Me HSiCI or Me 2 SiCI to carbanion 2.3a produced silane end-functionalized 3  2.8a and 2.9a, respectively (see Scheme 2.2). These compounds formed quantitatively from 2.3a according to the  31  NMR spectra of the reaction mixtures (2.8a ô  =  —23.9, 2.9a ó  =  —25.4),  however their high solubility resulted in low isolated yields of pure product after recrystallization (2.8a 50 %, 2.9a 14%). Analogous to that mentioned previously for 2.7a, the 1 H NMR signals for the ortho-methyl protons of the mesityl group were inequivalent and two broad signals were observed (2.8a ô  =  3.1 and 1.1; 2.9a ó  =  2.8 and 0.9). Importantly, for 2.8a a singlet resonance  was observed at 4.58 ppm which is assigned to the Si—H proton. Although the methyl protons of the SiMe 3 moiety are equivalent in 2.9a, the methyl protons of the 2 SiMe moiety are H inequivalent in 2.Ba. In particular, the SiHMe 2 group in 2.8a shows two sets of doublets at 0.10 ppm  JHH = 3 (  3 Hz) and 0.05 ppm  low resolution El MS (M: m/z  =  JHH = 3 (  3 Hz). Both 2.8a and 2.9a were also characterized by  390 2.8a; 404 2.9a), elemental analysis (2.8a only) and X-ray  crystallography. References start on page 45  Chapter 2  35  Crystals of 2.8a and 2.9a were obtained from hexanes. The solid-state molecular structures and important bond lengths and angles are given in Figure 2.3 and Figure 2.4, and additional data is provided in Table 2.1. As with the other model compounds, 2.4a and 2.7a, the H bond lengths [28a: P(1)—C(11) 2 P—CPh  =  1.902(1); 2.9a: P(1)—C(1)  =  1.920(1) A] are  significantly longer than the two other P—C bonds [avg. for 2.8a and 2.9a  =  1.835(5) A]. Similar  to that discussed previously, this elongation may be attributed to steric congestion. The small H moiety compared to the SiMe 2 3 moiety is reflected by the smaller P—C—Si size of the S1Me bond angles in 2.8a [2.8a: P(1)—C(11)—Si(1)  =  106.57(6)°; 2.9a: P(1)—C(1)—Si(1)  =  111.52(6)°].  Remarkably, these angles are much larger than the analogous angle in diphosphine 2.7a [P(1)— C(11)—P(2)  =  99.17(9)°] in which there is likely a weak PP interaction.  7)  07  C25 H24 023  c2 4 CSc 04  021  Cli  015  016  Figure 2.3 The solid-state molecular structure of 2.8a (50% probability ellipsoids). Hydrogen atoms are omitted for clarity except for H(1). Selected bond lengths (A): P(1)—C(1) = 1.834(2); P(1 )—C(1 0) = 1.824(2); P(1 )—C(1 1) = 1.902(1); Si(1 )—C(1 1) = 1.910(2); Si(1 )—C(24) = 1 .855(2); Si(1)—C(25) = 1.849(2); Si(1)—H(1) = 1.36(2). Selected bond angles (°): C(1)—P(1)—C(10) = 107.39(7); C(1)—P(1)—C(11) = 106.61 (6); C(10)—P(1)—C(11) = 102.33(7); P(1)—C(11)—Si(1) =  106.57(6).  References start on page 45  Chapter 2  36  Figure 2.4 The solid-state molecular structure of 2.9a (50% probability ellipsoids). Hydrogen atoms are omitted for clarity. Selected bond lengths (A): P(1)—C(1) = 1.920(1); P(l)—C(2) = 1.839(2); P(1)—C(3) = 1.844(1); C(1)—Si(1) = 1.944(1). Selected bond angles (°): C(1)—P(1)--C(2) = 101 .38(6); C(2)—P(1)—C(3) 106.97(7); C(1)—P(1)—C(3) = 107.53(5); P(1)—C(1)—Si(1) = 111.52(6).  2.3 Conclusion  In closing, the initiation and termination steps in the anionic polymerization of P=C bonds have been modeled. The initiation step was investigated through the stoichiometric reaction of 2 (2.1) with RLi (R MesP=CPh  =  Me or n-Bu). In all cases, the addition was highly regioselective  with the formal attack of R at phosphorus to give the carbanion Li[Mes(R)P—CPh } (2.3a/2.3b). 2 To simulate the termination step in the anionic polymerization of 2.1, carbanions 2.3a and 2.3b were quenched in situ with electrophiles such as: a proton (from H 0 or MeOH), a methyl cation 2 (from Mel), a phosphenium moiety (from CIP(NEt ) or a silylium moiety (from Me 2 HSiCI or 2 SiCI). In this way, five new tertiary phosphines and one diphosphine were accessed and will 3 Me function as models for poly(methylenephosphine)s. Four of these molecules were characterized crystallographically.  In future, this chemistry will be extended to the polymer 2.2 with the goal of preparing end-functional telechelic polymers that can be employed in the synthesis of novel block copolymers. In addition, these new compounds will be used to prepare molecular complexes References stan on page 45  Chapter 2  37  that will serve as models for macromolecular coordination complexes of poly(methylenephosphine)s.  2.4  2.4.1  Experimental  Materials and General Procedures All manipulations of oxygen- and/or moisture-sensitive compounds were performed  under a nitrogen atmosphere using standard Schlenk and/or glovebox techniques. Hexanes, diethyl ether and dichloromethane were deoxygenated with nitrogen and dried by passing through a column containing activated alumina. THF was freshly distilled from sodium/benzophenone ketyl. Distilled water and methanol were degassed prior to use. CDCI 3 was distilled from P 5 and degassed. 2 0 2 CI and C CD D were purchased from Cambridge 6 Isotope Laboratories and were dried over molecular sieves (3 A). PCI , HNEt 3 , Mel, MeLi (1.6 2 M in Et 0), n-BuLi (1.6 M in hexanes) were purchased from Aldrich and used as received. 2 Alkyllithium reagents were titrated prior to use against a THE solution of N-benzylbenzamide. SiHCI and Me 2 Me SiCI were distilled over CaH 3 2 and degassed prior to use. MesP=CPh , 2.1, 2 was prepared following literature 17 procedures. 18 ’  P, 31  H and 13 1 H} NMR spectra were recorded on BrukerAV300 orAV400 1 C{  spectrometers at room temperature. Solid-state NMR experiments were performed on a Bruker Avance DSX400 spectrometer operating at frequencies of 400.13 MHz and 161.98 MHz for 1 H and 31 P respectively, using a Bruker triple resonance 4mm MAS probe. Chemical shifts for 31 P NMR spectra are reported relative to 4 P0 as an external standard (85% in H 3 H 0, 3 2 Chemical shifts for 13 H} NMR spectra are reported relative to 2 1 C{ CI (ó CD  =  =  3 (ó 54.0) or CDCI  77.2). Chemical shifts for 1 H NMR spectra are reported relative to residual CHDCI 2 (8 3 (8 CHCI  =  7.27) or 5 HD (8 6 C  =  0).  =  =  5.32) or  7.16). Mass spectra were recorded on a Kratos MS 50 References start on page 45  Chapter 2  38  instrument and performed by the UBC Mass Spectrometry Centre staff. Elemental analyses were performed by Mr. Minaz Lakha in the Departmental Microanalysis Facility.  2.4.2  Preparation of Mes(Me)P-CPh Li (2.3a) 2 Typical Procedure: To a cooled (—78°C) solution of phosphaalkene 2.1 (2.06 g, 6.5  mmol) in THF or Et 0 (Ca. 150 mL) was slowly added MeLi in Et 2 0 (5.2 mL, 1.5 M, 7.8 mmol). 2 Upon addition, there was an immediate colour change from yellow to dark red. The cooled solution was stirred for 1 h and then warmed to room temperature whereupon it was stirred for an additional 1 h. The concentration for use in subsequent steps was 0.043 M (see preparation of 2.4a). 31 P{’H} NMR spectroscopy of an aliquot removed from the reaction mixture showed a single signal (ö  2.4.3  =  —42.0 in THF, —44.3 in Et 0). 2  Preparation of Mes(n—Bu)P-CPh Li (2.3b) 2 To a stirred yellow solution of 2.1 (0.64 g, 2.0 mmol) in Et 0 (ca. 30 mL) at —78 °C, a 2  solution of n-BuLi in hexanes (3.0 mL, 1.4 M, 4.2 mmol) was added rapidly. The mixture turned bright orange upon addition, and was stirred at —78 °C for 30 mins. Subsequently, the solution was warmed to room temperature whereupon it was stirred for an additional 1 h. Over this time, the solution turned from bright orange to red. The reaction was monitored by 31 H} NMR 1 P{ spectroscopy, affording a single signal for 2.3b (ó  =  —31.1). This solution was used in the  preparation of 2.4b.  2.4.4  Preparation of Mes(Me)P—CPh H (2.4a) 2 To a stirred red solution of 2.3a in THE (150 mL, 0.043 M, 6.4 mmol), was added  degassed MeOH (0.4 mL). From the resulting colourless solution, THE was removed in vacuo affording a white solid residue. The soluble fraction was extracted into hexanes (3 x 50 mL) and the resulting solution was evaporated to dryness affording a yellow oil. The oil was dissolved in References start on page 45  Chapter 2  39  minimal hexanes at reflux (Ca. 5 mL). The solution was slowly cooled to room temperature to afford colourless crystals suitable for X-ray diffraction. Yield: 0.50 g (24 %).  H} NMR 2 1 P{ 31 H NMR 2 CI 121.5 MHz): ô =—24.0 (s); 1 (CD , CI 300 MHz): (CD , 7.10 (m, 1OH, Ph-I-i), 6.77 (s, 2H, m-Mes-I-I), 4.87 (d, ), 1.31 (d, 3 Mes-CH ) 3 , 2.21 (s, 3H, p-Mes-CH 75.5 MHz) (unassigned): ö  =  146.0 (d,  140.4 (s), 131 .4—1 27.4 (m), 52.8 (d,  Jcp=  Jcp= 1  ); MS (El, 70 eV): m/z (%) 3 Hz, P—CH  =  JHP= 2  JHP= 2  7.58—  I-i), 2.52 (s, 6H, o 2 5 Hz, 1H, CPh  CI (CD , 6Hz, 3H, 3 P—CH ) ; C{ 13 H 1 } NMR 2  15 Hz), 144.3, 144.1, 144.0, 143.8(4  16 Hz), 24.6, 24.4(2  x  s or 1  x  x  s or 2  d), 10.8 (d,  d),  x  18  Jcp 1  332 (28) [Mt], 167 (100) 2 [CHPh ] , 165 (44) 2 [M—CHPh ] ,  119 (12) [Mes}.  2.4.5  Preparation of Mes(n-Bu)P—CPh H (2.4b) 2 To a stirred solution of carbanion 2.3b in Et 0 (2.0 mmol; preparation described above) 2  0 until the reaction mixture turned pale yellow (several 2 was added dropwise degassed H , filtered, and the soluble fraction was extracted 4 drops). The mixture was then dried with MgSO with Et 0 (2 2  x  10 mL). The solvent was removed in vacuo at 60 °C to afford pure 2.4b as a pale  yellow oil. Yield: 0.65 g (85 %).  p NMR 2 31 CI 121.5 MHz): ô (CD ,  =  —12.4 (s); 1 H NMR 2 CI 400 MHz) (assignments (CD ,  made with the aid of a COSY experiment): o  =  7.57 (d,  JHH =  8 Hz, 2H, Ph-I-i), 7.36 (m, 4H, Ph  H), 7.24 (m, 1H, Ph-H), 7.15 (m, 2H, Ph-H), 7.06 (m, 1H, Ph-H), 6.77 (brs, 2H, m-Mes-H), 4.91 (d,  JPH = 2  5 Hz, 1 H, CPh H), 2.56 (br s, 6H, 3 2 o-Mes-CH ) , 2.20 (s, 3H, 3 p-Mes-CH ) , 2.02 (m, 1 H,  P-CHI-i), 1.55 (m, 1H, P-CHH), 1.22 (m, 2H, 3 CH C 2 ) H , 1.08 (m, 2H, 2 CH PCH ) , 0.74 (t, =  JHH  7 Hz, 3H, 3 CH 2 CH ) ; 13 H} NMR 2 1 C{ CI 100.6 MHz) (assignments made with the aid of (CD ,  HMQC/HMBC experiments): .3  143.6 (d,  Jcp = 2  12 Hz, i-Ph-C), 143.4 (d,  139.5 (s, p-Mes-C), 130.2 (br, m-Mes-C), 129.7 (d,  Jc’ = 1  Jcp = 2  13 Hz, iPh-C),  26 Hz, i-Mes-C), 129.5 (d,  Jcp = 3  9  References start on page 45  Chapter 2  40  Hz, o-Ph-C), 129.1 (s, o-Mes-C), 128.9 (d, Jcp 4  Jcp = 2 Hz, rn-Ph-C), 126.5 (d, 4  (v  ), 21.2 3 br, o-Mes-CH  (s,  9 Hz, o-Ph-C), 128.6 (s, p-Ph-C), 127.1 (d,  2 Hz, rn-Ph-C), 51.6 (d, 1 Jcp  CH P—CH ) , 25.5 (d, 1 = 20 Hz, 2 Jcp 23.8  Jcp = 3  16 Hz, 2 CHPh ) , 30.2 (d,  16 Hz, 2 JCp P—CH ) , 24.7 (d, 3  p-Mes-CH ) 3 , 14.1  (s,  13 Hz, ) 3 CH C 2 H ,  3 C 2 CH ) H . MS (El, 70eV): mlz (%) = 374  H], 151 (24) [PMes]. Anal.: calculated = C, 83.39%; H, 8.34%. 2 (29) [M], 167 (100) [CPh C, 83.81%; H, 8.34%.  Found  =  2.4.6  Synthesis of 2 Mes(Me)P—CPh M e (2.6a) Mel (1.6 mL, 26 mmol) was added dropwiseto a solution of 2.3a in Et 0 (160 mL, 0.16 2  M, 26 mmol). The solution was stirred for 30 mm over which time its colour changed from red to orange. The solvent was removed in vacuo, the soluble fraction was extracted with hexanes, and evaporated to dryness. The product was purified by sublimation (140 °C, 0.1 mmHg). Yield = 5.7 g (64 %).  P NMR (CDCI 31 , 121.5 MHz): 3  o =—13.5  , 300 MHz): ó = 7.47 (m, 2H, 3 (s); 1 H NMR (CDCI  Ph-H), 7.21 (m, 6H, Ph-H), 7.01 (m, 2H, Ph-H), 6.74 (s, 2H, Mes-H), 2.23 (s, 3H, 3 p-Mes-CH ) , ), 1.70 (d, 3 1.87 (br, 6H, o-Mes-CH  JPH 2  = 13Hz, 3H, 3 P—CH ) , 1.39 (d, 3 JpH = 7 Hz, 3H,  H} NMR (CDCI 1 C{ , 75.5 MHz,) (unassigned): ô = 148.3 (d, Jcp= 14Hz), 146.3 (d, 3 3 C 2 CPh ) H ; 13 Jc  = 16 Hz), 144.7 (s), 138.8 (s), 129.9 (s), 128.7—127.4 (m), 125.8 (s), 125.4 (s), 49.1 (d, Jc  = 24 Hz), 28.8 (d,  Jcp  = 15 Hz), 23.5 (d,  Jc=  18 Hz), 20.8 (s), 9.0 (d,  Jcp= 1  21 Hz, 3 P—CH ) ; MS  (El, 70 eV): m/z (%): 346 (7) [Mt], 181 (100) [M— P(Mes)(CH )], 165 (16) [M— ) 3 3 ( 2 CPh CH ], 119 (5) [Mes].  2.4.7  Preparation of CIP(NEt ) 2 ) was prepared from an adaptation of literature method. 2 CIP(NEt 29 A solution of HNEt 2  (190 mL, 1.84 mol) and 2 CI (300 mL) was added slowly to a cooled (-78°C) solution of PCI CH 3  References start on page 45  Chapter 2  41  (40 mL, 0.46 mol) in 2 CI (250 mL). The reaction mixture was slowly warmed to room CH temperature and stirred for 1 h. Solvent was removed in vacuo. The resulting solid was extracted with hexanes (3 x 150 mL) and filtered. Hexanes were removed in vacuo. The resulting oil was distilled under vacuum yielding a colourless liquid (89 g, 92%).  P{’H} NMR (C 31 , 121.5 MHz): ô D 6 8H, CH ); 0.94 (t, 12H, 2  2.4.8  JHH = 3  =  154.8. 1 H NMR (C , 300 MHz): ó 6 D 5  2.9—3.1 (m,  7 Hz, CH ). 3  Preparation of Mes(Me)P—CPh —P(N Et 2 ) (2.7a) 2 To a cooled (0 °C) solution of 2.3a in THF (20 mL, 0.32 M, 6.4 mmol) was slowly added  a solution of CIP(NEt ) (1.50 g, 7.1 mmol) in THE (20 mL). An aliquot was removed from the 2 yellow reaction mixture for 31 P NMR spectroscopic analysis. After evaporation of the volatiles in vacuo, the soluble fraction was extracted into toluene (30 mL). Removal of the toluene in vacuo afforded the crude product which was washed with hexanes at —78 °C two times. Crystals suitable for X-ray diffraction were obtained by slow evaporation of a saturated toluene solution. Yield: 1.73 g (54 %).  P NMR (CDCI 31 , 121.5 MHz): 6 3  =  105.3 (d,  Jpp= 2  205 Hz, PN ), —9.4 (d, 2  PMes); 31 P MAS NMR (8.5 kHz, recycle delay of 20s, 162.0 MHz): 6 ), -7.9 (d, 2 PN  Jpp = 2  255 Hz, PMes); 1 H NMR (CDCI , 400 MHz) 6 3  =  =  108.3 (d,  Jpp= 2  Jpp 2  205 Hz, 255 Hz,  7.79 (br, 2H, Ph-H), 7.43  (br, 2H, Ph-H), 7.28—7.14 (m, 6H, Ph-I-i), 6.90 (br, IH, m-Mes-I-i), 6.55 (br, 1H m-Mes-H), 3.01  — 2.52 (m, 11 H, NCH 2 and o-Mes-CH ), 2.25 (s, 3H, 3 3 p-Mes-CH ) , 1.38 (d, ), 0.97 (m, 9H, 3 3 CH CH and 3 2 NCH o-Mes-CH ) , 0.84 (t, 6H,  JHH=  JpH = 2  9 Hz, 3H, P  7Hz, ) 3 C 2 NCH H ; 13 H} NMR 1 C{  , 100.6 MHz) (assignments made with the aid of HMQC/HMBC experiments): 6 3 (CDCI (s, o-Mes-C), 141.3 (br, Ar-C), 141.0 (t,  Jpc=  =  147.7  5Hz, Ar-C), 138.6 (s, p-Mes-C), 131.9—127.6 (m,  Ar-C), 126.9 (s, Ar-C), 126.4 (s, Ar-C), 124.8 (d,  Jc=  4 Hz, Ar-C), 63.9 (dd, 1 Jpc  46 and 34  References start on page 45  Chapter 2  42  Hz, P-CPh -P), 44.5 (d, 2  Jpc = 2  21 Hz, N-CH ), 44.0 (d, 2 2 ), 26.2 (br 2 Jc = 20 Hz, N-CH  ), 21.6 (brs, o-Mes-CH 3 Mes-CH ), 21.0 (s, p-Mes-CH 3 ), 14.5 (d, 3 (d, 3 CH 2 NCH ) , 9.7 (t, 1 Jpc Jpc = 5 Hz, 3  2.4.9  =  Jpc= 3  5, O  3Hz, 3 CH 2 NCH ) , 14.0  22 Hz, P—CH ). 3  Preparation of 2 —S1Me (2.8a) Mes(Me)P—CPh H HSiCI 2 To the red solution of 2.3a (40 mL, 0.079 M, 3.2 mmol) in THE (40 mL) neat Me  (0.5 mL, 4.6 mmol) was added. An immediate colour change to yellow was observed. The solvent was removed in vacuo, and the residue was dissolved in hexanes (3 x 5 mL). Following solvent evaporation, the crude product was recrystallized from a minimal amount of hot hexanes in an inert atmosphere to afford large colourless crystals. Yield: 0.62 g (50%).  p NMR (C 31 , 121.5 MHz): ô =—23.9 (s); 1 D 6 H NMR(C , 300 MHz): ô D 6  =  7.70 (brs, 2H,  Ph), 7.3—6.5 (m, IOH, Ph and m-Mes-H), 4.58 (brs, 1H, Si-H), 3.1 (brs, 3H, o-Mes-CH ), 2.18 3 ), 1.45 (d, 3 (s, 3H, p-Mes-CH 3 Hz, 3H, Si—CH ), 0.05 (d, 3  JPH =  JHH 3  =  8Hz, 3H, P—CH ), 1.1 (brs, 3H, o-Mes-CH 3 ), 0.10 (d, 3  Mes-C), 142.5 (s, Mes-C), 142.1 (d,  ), -3.96 (d, 3 3 PCH Jpc  =  =  Jpc = 1  =  147.6 (s, Mes-C), 147.3 (s,  7Hz, i-Mes-C), 139.5 (s, Mes-C), 131 - 128 (m, Ph-  45 Hz, PCPh ), 21.2 (s, p-Mes-CH 2 ), 7.81 (d, 3  ), —5.66 (d, 3 3 5 Hz, SiCH Jpc  =  =  Jpc = 1  23 Hz,  6 Hz, SiCH ). MS (El, 70 eV): m/z (%) 3  390 (38) [Mt], 375 (17) [Mt— CH }, 332 (45) [M — SiMe 3 ], 223 (69) [M 2 ]. Anal.: calculated 2 [CPh  =  3 Hz, 3H, Si—CH ); 13 3 H} NMR 2 1 C{ CI 75.5 MHz) (CD ,  (assignments made with the aid of HMQC/HMBC experiments): ô  C), 125.7 (s, Ph-C), 45.7 (d, 1 Jpc  JHH 3  C, 76.88%; H, 8.00%. Found  =  —  =  PMesMe], 167 (100)  C, 77.20 %; H, 7.64 %.  2.4.10 Preparation of 3 —SiMe (2.9a) 2 Mes(Me)P—CPh To the red solution of 2.3a in Et 0 (22 mL, 0.14 M, 3.2 mmol) neat Me 2 SiCI (0.4 mL, 3.2 3 mmol) was added. An immediate colour change to yellow was observed accompanied by the formation of a white precipitate. The solution was filtered, the solvent was removed in vacuo,  References start on page 45  Chapter 2  43  Et (3 x 15 mL). The Et 0 0 was removed in 2 and the soluble fraction was extracted into 2 vacuo. The crude product was dissolved in a minimal amount of hexanes and slow evaporation afforded colourless crystals suitable for X-ray crystallography. Yield  , 121.5 MHz): ô 3 P NMR (CDCI 31 2H, Ph), 7.3  —  JPH = 2  MS (El, 70 eV): m/z —  0.18 g (14 %)  —25.4 (s); 1 H NMR (CDCI , 300 MHz): ó 3  =  7.6 (br s,  ), 2.22 (s, 3H, p 3 7.1 (m, 8H, Ph). 6.8 (br s, 2H, m-Mes-H), 2.8 (br s, o-Mes-CH  ), 1.33 (d, 3 Mes-CH  [M  =  =  (%)  =  ), —0.02 (s, 9H, Si(CH 3 ). ) 3 8 Hz, 3H, P—CH ), 0.9 (br s, 3H, o-Mes-CH 3 404 (100) [M], 389 (26) [M  SiMe 2 CPh ] 3 , 73 (34) [M  —  —  ], 331 (44) [M 3 CH  —  ], 167 (39) 3 SiMe  ]. 2 MesMePCPh  2.4.11 X-ray Crystallography Crystal data and refinement parameters are listed in Table 2.1.1 All single crystals were immersed in oil and mounted on a glass fiber. Data for 2.4a were collected by Dr. Brian 0. Patrick on a Bruker X8 APEX diffractometer with graphite-monochromated Mo Ka radiation. Data for 2.7a, 2.8a and 2.9a were collected by Joshua Bates on a Bruker X8 APEX II ° 3 diffractometer. Data was collected and integrated using the Bruker SAINT software package. All structures were solved by direct methods and subsequent Fourier difference techniques and were refined anisotropically for all non-hydrogen atoms. Hydrogen atoms were included in idealized positions and refined isotropically except in 2.4a where they were not refined. All data sets were corrected for Lorentz and polarization effects. All calculations were performed using the SHELXTL crystallographic software package from Bruker-AXS. 31  Compounds 2.4a, 2.8a and 2.9a did not show any crystallographic complexity. Compound 2.7a was a split crystal and cell_now (within SAINT) was used to determine that the second domain was rotated from the first domain by  4•40•  Only the first domain was integrated  ‘.cif files have been deposited with the Cambridge Crystallographic Database. Depository numbers: CCDC 655085 (2.4a), CCDC 655086 (2.7a), CCDC 655087 (2.8a), CCDC 655088 (2.9a). References start on page 45  Chapter 2  44  because there was little or no overlap between the two lattices. One of the ethyl groups was disordered at C(28) and C(29). The disorder at carbon was modeled by including two additional carbon atoms [C(28b) and C(29b)] and refining their respective populations [occupancy 0.78(2) and 0.22(2)].  X-ray crystallographic data for 2.4a, 2.7a, 2.8a and 2.9a. 2.4a 2.7a 2.8a formula C 2 H P 3 5 34 C 4 H P 2 N 1 21 C 3 H PS1 5 formula weight (g moF ) 1 332.40 506.62 390.56 crystal system monoclinic monoclinic monoclinic space group P21/c P21/n C2/c colour colourless colourless colourless 18.867(2) 9.528(5) 20.677(5) a (A) 6.1290(5) 15.614(5) 8.955(5) b (A) 16.618(2) 18.935(5) 23.987(5) c(A) a(deg) 90 90 90 f3 (deg) 92.401(3) 94.828(5) 101.555(5) y(deg) 90 90 90 ) 3 V(A 1919.9(3) 2807.0(19) 4351(3) Z 4 4 8 T(K) 173(2) 173(2) 173(2) i(Mo Ka) (cm 1 ) 1 1.44 1.77 1.89 0.2 x 0.2 x 0.1 1.4 x 0.6x 0.4 1.4 x 1.2x 1.0 crystal size (mm) ) 3 1.150 1.199 1.192 dcalcd (g cm 20(max) (deg) 56.02 56.04 56.36 no. of rflns 26221 27995 54740 4580 6560 5281 no. of unique data R(int) 0.040 0.050 0.033 rfln/param ratio 20.82 12.84 14.35 a Ri, wR2 [I > 2.000(l)] 0.0388, 0.0925 0.0418, 0.0944 0.0350, 0.0883 Ri, wR2 (all data)a 0.0662, 0.1015 0.0787, 0.1149 0.0446, 0.0950 GOF 1.053 1.017 1.029 a Fcz)z/Zw(Foz)9z. 1 = R 2 = [Z(F ’ 0 1 ; wR 0 I F I FI 1/ZI F  Table 2.1  2.9a 23 C 3 H PS1 6 404.58 triclinic p1  colourless 9.165(5) 10.757(5) 12.689(5) 79.511(5) 71.398(5) 75.169(5) 1143.3(9) 2 173(2) 1.82 lOx lOx 0.5 1.175 55.66 27579 5333 0.024 13.85 0.0306, 0.0820 0.0354, 0.0862 1.054  —  —  References start on page 45  Chapter 2 25  45  References  1. C.-W. Tsang, M. Yam, D. P. Gates. J. Am. Chem. Soc. 2003, 125, 1480. 2. B. H. Gillon, D. P. Gates. Chem. Commun. 2004, 1868. 3. K. J. T. Noonan, D. P. Gates. Angew. Chem.  mt.  Ed. 2006, 45, 7271.  4. T. A. van der Knaap, F. Bickeihaupt. Tetrahedron Lett. 1982, 23, 2037. 5. B.-L. Li, R. H. Neilson. lnorg. Chem. 1984, 23, 3665. 6. Z.-M. Xie, P. Wisian-Neilson, R. H. Neilson. Organometallics 1985, 4, 339. 7. R. Appel, C. Casser, F. Knoch. Chem. Ber. 1986, 119, 2609. 8. S. Ito, H. Miyake, M. Yoshifuji, T. HoItzI, T. Veszpremi. Chem.-Eur. J. 2005, 11, 5960. 9. S. Ito, H. Miyake, H. Sugiyama, M. Yoshifuji. Tetrahedron Lett. 2004, 45, 7019. 10. A. Moores, L. Ricard, P. Le Floch. Angew. Chem.  mt.  Ed. 2003, 42, 4940.  11. G. Markl, A. Merz. Tetrahedron Lett. 1968, 3611. 12. G. Marki, F. Lieb, A. Merz. Angew. Chem.  mt.  Ed. 1967, 6, 87.  13. S. Ito, M. Freytag, M. Yoshifuji. Dalton Trans. 2006, 710. 14. S. Ito, K. Toyota, M. Yoshifuji. Chem. Commun. 1997, 1637. 15. M. Yoshifuji, H. Kawanami, Y. Kawai, K. Toyota, M. Yasunami, T. Niitsu, N. Inamoto. Chem. Lett. 1992, 1053. 16. F. B. Simon J. Goede. Chemische Berichte 1991, 124, 2677. 17. G. Becker, W. Uhi, H.-J. Wessely. Z. Anorg. AlIg. Chem. 1981, 479, 41. 18. M. Yam, J. H. Chong, C.-W. Tsang, B. 0. Patrick, A. E. Lam, D. P. Gates. lnorg. Chem. 2006, 45, 5225. 19. C. A. Tolman. Chem. Rev. 1977, 77, 313. 20. “Characteristic Bond Lengths in Free Molecules” in CRC Handbook of Chemistry and Physics, 84th Edition. CRC Press: Boca Raton, FL, 2003.  References start on page 45  Chapter 2  46  21. P. Maire, S. Deblon, F. Breher, J. Geier, C. Böhler, H. Ruegger, H. SchOnberg, H. Grützmacher. Chem. Eur. J. 2004, 10, 4198. 22. B. Manz, G. Maas. J. Chem. Soc., Chem. Commun. 1995, 25. 23. A. D. Burrows, M. F. Mahon, S. P. Nolan, M. Varrone. lnorg. Chem. 2003, 42, 7227. 24. L. Pauling, The Nature of the Chemical Bond and the Structure of Molecules and Crystals; An Introduction to Modern Structural Chemistry. 3rd ed.; Cornell University Press: New York, 1960; p 664. 25. P. W. Dyer, J. Fawcett, M. J. Hanton, R. D. W. Kemmitt, R. Padda, N. Singh. Dalton Trans. 2003, 104. 26. F. Dahan, P. W. Dyer, M. J. Hanton, M. Jones, D. M. P. Mingos, A. J. P. White, D. J. Williams, A.-M. Williamson. Eur. J. lnorg. Chem. 2002, 732. 27. I. Shevchenko, V. Andrushko, E. Lork, G.-V. Röschenthaler. Eur. J. lnorg. Chem. 2002, 2985. 28. S. A. Reiter, S. D. Nogai, H. Schmidbaur. Dalton Trans. 2005, 247. 29. P. G. Chantrell, C. A. Pearce, C. R. Torer, R. J. Twaits. J. Appi. Chem. 1964, 14, 563. 30. Computer program: SAINT V. 7.03A ed. Bruker AXS Inc., Madison, WI. (1997-2003). 31. Computer program: SHELXTLV. 5.1 ed. BrukerAXS Inc., Madison, WI. (1997).  References start on page 45  47  Chapter 3  Anionic Oligomerization of Phosphaalkenes: Analysis by MALDI-TOF Mass S pectrometry*  3.1  Introduction  The addition polymerization of olefins is one of the most important methods of polymer synthesis and forms the basis for the production of many commodity organic materials. There has been considerable interest in the synthesis and reactions of phosphaalkenes, and the remarkable parallels that exist between P=C and C=C bonds in molecular chemistry. 13 Our group has been interested in expanding the so-called “phosphorus—carbon analogy” widely established in molecular chemistry to polymer science, and has recently reported the high temperature polymerization of phosphaalkene 3.1 to give poly(methylenephosphine) 3.2.  Ph / P=C \ / Mes Ph 3.1  Radical or Anionic Initiator ..  F I  Ph] ..  -I-—P—C I I I Ph  LMeS  n  3.2  Previously, addition polymerization was often dismissed as unsuitable for inorganic systems. Now that 3.1 has been polymerized, one question that must be addressed is whether the initiation, propagation and termination steps are analogous to those known for olefins. If so, by analogy with olefins, living polymers and novel block or end-functionalized polymers may be accessible. Knowledge of the structure of polymer 3.2, including end-groups, will provide insight into the mechanism of polymerization. *  A portion of this chapter has been published as a preliminary communication. Bronwyn H. Gillon, and Derek P. Gates, “Analysis of the products of the anionic oligomerisation of a phosphaalkene using MALDI-TOF mass spectrometry,” Chem. Commun. 2004, 1868—1 869. Copyright 2004 Royal Society of Chemistry.  48  Chapter 3 The proposed mechanism of propagation occurs in an analogous fashion to that for olefins. A propagating anion will act as a nucleophile and add to the electrophilic phosphorus atom of the P=C bond, increasing the chain length by one repeat unit. This propagating anion can go on to add to another monomer (see Figure 3.1). Finally, when the monomers are  completely consumed, addition of an electrophile terminates the polymerization. The polymers are proposed to be linear chains made up of P-C repeat units with terminal groups from the alkyl lithium initiator (R) and the electrophile (E).  Initiation:  R:e  T  Propagation.  I II  —c:e 5 R—i  =c 5 1  /  \  if  I.. Il R+P_C+:e I]  /  PC  \  F ii r LI I]  R-’-P—C-I—:e m  Figure 3.1 P=C bonds.  I.. I  :e  R-I-P—C  L’  Termination:  r  m>n  F ii LI I]  -P—C— R1 E m  Mechanism of anionic polymerization (initiation, propagation and termination) for  In Chapter 2, the syntheses of model compounds (3.4a-f) were described which provided invaluable insight into the regioselectivity of the addition of alkyllithium initiators (RLi) to the P=C bonds. The addition of the anionic initiator (R) occurs at the phosphorus atom (see Scheme 3.1) of the phosphaalkene 3.1. Subsequent addition of an electrophile (E) occurs at the benzylic carbon of the phosphorus-containing anion (either 3.3a or 3.3b). With the addition of various electrophiles, a range of possible end-groups (from a simple proton to silylium and phosphenium moieties) was tested in the hopes of preparing telechelic polymers. Missing from these model compounds is information on the interactions connecting the monomers in the  References start on page 72  Chapter 3  49  polymer 3.2. In an effort to understand the propagation step of the polymerization of poly(methylenephoshine) 3.2, the characterization of oligomers could prove useful.  RLi  /  ‘  Mes  Ph  Ph  Ph  EX  R_P_C:eeLi  R—P—C—E  II  II  Ph  Mes Ph 3.3a: R 3.3b: R  3.1  = =  Mes Ph  -  Me; n-Bu  3.4a: 3.4b: 3.4c: 3.4d: 3.4e: 3.4f:  R R R R R R  Me, E=H; Me, E Me; = n-Bu, E = H; ; ) 2 = Me, E = P(NEt = Me, E ; 3 SiMe = Me, E = SIHMe 2 =  =  Scheme 3.1  The anionically initiated dimerization of a phosphaalkene 3.5 has been previously reported to form 3.6. Like our system, the alkyl anion added across the double bond at the phosphorus atom. 6 However, phosphaalkene 3.5 was serendipitously prepared in the reaction mixture and was the proposed intermediate en route to dimer 3.6. The subsequent dimerization was suggested to have occurred through an analogous mechanism to that proposed in Figure 3.1. Upon addition of Me SiCl, the propagating anion was quenched resulting in the dimeric 3.6 3 that was isolated as a colourless liquid in high yield and characterized by NMR spectroscopy.  3 SiMe 2 / Me  ‘  H 3.5  MeLi S1CI 3 Me -Lid  r  3 SiMe  MeI-P—C II I  LMeH  3.6  3 SiMe 2  In this chapter, the ambient temperature oligomerization of 3.1 using anionic initiators and the characterization of the resulting oligomers using MALDI-TOF MS is reported. Also, the anionic oligomerization is extended to other phosphaalkene monomers. To my knowledge, oligomeric phosphaalkenes larger than diphosphetaines (cyclic dimers) have not previously been characterized by mass spectrometry. 78 Some examples of phosphaalkyne  References start on page 72  Chapter 3 oligomerizations are known as well,  50 9-13  though the synthesis of linear species is contentious.’ 4  15  3.2  Results and Discussions  The emergence of soft ionization (i.e. MALDI) mass spectrometric techniques to investigate high molecular weight (MW) macromolecules is revolutionizing the characterization of synthetic polymers, 1621 however the use of such methods is still relatively uncommon in the analysis of inorganic systems. 2226 Importantly, MALDI-TOF MS gives absolute masses rather than relative (i.e. GPC) and usually molecular ions are observed without fragmentation. The analysis of oligo(methylenephosphine)s 3.2 by MALDI-TOF MS is of particular interest. One objective is to obtain accurate MWs for 3.2 since laser light-scattering has shown that the MW is underestimated by GPC (vs polystyrene standards). 4 Moreover, MALDI-TOF MS may provide mechanistic insight into this new polymerization reaction by identifying end-groups that have remained undetectable by NMR spectroscopy. To date, analysis of polymeric samples of 3.2 by MALDI-TOF MS has not been successful; therefore, small oligomers have been synthesized that are analyzable using MALDI techniques.  3.2.1  Preparation of oxidized oligomers from anionically initiated MesP=CPh 2 to form  ]H, 3.9a 2 Me[(Mes)P(=O)-CPh The preparation of the oligomers (3.9a) was planned similarly to the preparation of model compound 3.4a. Instead of quenching the anion 3.3a with an electrophile, the anion was treated with additional equivalents of phosphaalkene 3.1 to favour oligomerization.  Phosphaalkene 3.1 was dissolved in THF and cooled to —80 °C, to which was added a slight excess of MeLi in diethyl ether. The reaction mixture was stirred while slowly being warmed to room temperature. An aliquot of the dark red solution was removed and analyzed by References start on page 72  51  Chapter 3 P NMR spectroscopy. A singlet resonance at —45 ppm was observed and assigned to 31 Li (3.3a). 2 Mes(Me)P—C(Ph) 5 A solution of phosphaalkene 3.1 (3 equivs) in THF was added to  the reaction mixture which was stirred overnight. Another aliquot was removed from the reaction mixture and was analyzed by 31 P NMR spectroscopy. The spectrum revealed a broad resonance centered at —7 ppm assigned to 3.8a which is similar for that of the polymer 3.2 =  (ó31p  —1 O). Addition of degassed H 0 to the reaction mixture afforded a pale yellow solution. 2  Removal of the solvents in vacuo resulted in a yellow oil that was dissolved in diethyl ether and subsequently treated with excess H 0 to oxidize the phosphine atoms. After isolation, the 2 oxidized oligomers 3.9a were dissolved in minimal 2 CI and were precipitated by adding CH hexanes rapidly to the solution. Analysis of the precipitated product by 31 P NMR spectroscopy revealed that, analogous to the oxidized polymer, only a broad signal (ô  =  45 ppm) was  observed. The 1 H NMR spectrum showed two very broad resonances in the alkyl and aryl regions in the range observed for phosphine polymer 3.2, but offered no other useful information (for example, the presence and nature of endgroups or  Ph  Ph MeLi EtO -78 °C Ph  / Mes 3.1  coupling).  2or3equiv3.1  Me—P—C—Li  I  I  Phi  —P—C— Me— 1 Li  I I  0 2 Et  Mes Ph 3.3a  r  I  LMeS PhJ 3.7a MeOH or 0 2 H  ro I II  Phi  I  I  Me-I—P—C--I-H  II  II  LMes PhJ 3.9a  4  0 2 H  r I  Phi ..  I  I  Me+-P—C—I-H  II  II  LMes PhJ 3.8a  In order to further characterize the products, MALDI-TOF mass spectrometry was employed. A sample for MALDI-TOF MS analysis was prepared using the layer method through the deposition of a THF solution of the matrix 2,5-dihydroxybenzoic acid (DHB) followed by a CI solution of oligomers 3.9a. CH 2 17 A typical mass spectrum is shown in Figure 3.2 and  References start on page 72  52  Chapter 3 selective data are collected in Table 3.1. Remarkably, a series of ions spaced by the mass of the monomer unit (332 Da) were observed that were assigned to linear oligomers 3.9a (n  =  3  —  11). The masses were within experimental accuracy (± 0.1%) of the calculated masses for protonated species (3.9a +H) (ca  ±  2 Da). For example, inset A in Figure 3.2 clearly shows an  isotope pattern with lowest mass 1676 Da which is 1 less than (3.9 a+H) P 5 110 calcd. H 111 (C ; 0 5 1677 g mor ). The isotope pattern is consistent with that expected with the most intense ion due 1 to the presence of I x 13 C (observed at 1677). Remarkably, oligomers of up to 11 repeat units a +H), 3669 Da; calcd., 3669 g mor 11 [(3.9 j were observed and for this ion with 243 C atoms, 1 the most intense ion was due to the presence of 2 x 13 C in the oligomer which is consistent with the expected isotope pattern. The observation of ions consistent with the presence of CH 3 and H end-groups in 3.9a suggests that linear products are obtained and that the mechanism of chain growth is analogous to that for olefins.  References start on page 72  Chapter 3  a.  53  a 5 3.9  a 3 39  31 0 a 5  Inset B  InsetA  2000-  a+O)* 5 (3.1 0  a 4 3.9 a 5 3.12  15001830  1850  1870  mlz  a+O)* 5 (3.9  1000-  a 5 311  a 5 39  __n1670 1690  a 3 3.10  -r  1710  m/z  a 6 39  500-  a 7 39  a 4 310  39a  I  3Sa  3.9a  LJL LJL.. LL L3*?07aL1O8aL 3 ’V’ 1400  1900  2400  2900 *  Figure 3.2  MALDI-TOF MS of oligomer mixture, 3.9a.  Table 3.1  Selected MALDI-TOF MS data for oligomeric mixture 3.9a Calculated Found n MW (g moF ) MW (g moF 1 ) 1 1 348.2 N/A 2 680.3 679 3 1012.4 1011 4 1344.6 1343 5 1676.7 1675 6 2008.9 2007 7 2341.0 2339 8 2673.1 2671 9 10 11  3005.3 3337.4 3669.5  3400  m/z  tentative assignment.  3004 3337 3669  One puzzling feature of the MALDI-TOF mass spectrum in Figure 3.2, is the unexpected presence of a second series of oligomers spaced by the monomer unit (332 Da). This second series can clearly be seen in Figure 3.2. Remarkably, each peak in this series is situated exactly  References start on page 72  Chapter 3  54  halfway (i.e. ±166 Da) between the ions assigned to the linear oligomers (3.9a). This observation might possibly be attributed to multiply charged species. However, on close inspection of the mass spectra this hypothesis can be ruled out since the ions were spaced by integer mass units. If a complex were doubly charged, the difference between peaks would be 0.5 Da. If the P—C bond in a repeat unit were to be broken, each moiety (MeP=O and CPh ) has 2 a mass of 166 Da. Given this fact, these signals are assigned to linear oligomers with an extra phosphorus group at the end of the chain (3.1Oa). Figure 3.2, inset B, shows signals consistent with 3.10 a with calculated mass of 1842 Da. Structures with an extra CR 5 2 and P—Me end-group are unlikely since a 2 —CPh backbone linkage would be necessary to account for the CPh observed masses. The reason for the presence of this second distribution of ions assigned to 3.1Oa is not obvious, although there are a number of possibilities: e.g. backbiting during the oligomerization, decomposition during oxidation, or fragmention during ionization.  RLP-C-]-P_H  LMs  Ph] es  3.1Oa R 3.1Ob R  3.2.2  Origins of 3.1Oa  —  -1- J-X-10 -L-  =  Me  =  n-Bu  3.11  3.12  The “Second Distribution”  Various experiments were performed in order to determine the source of the unexpected “second distribution” of ions. The potential sources were decomposition during oxidation, backbiting during oligomerization or fragmentation during mass spectrometry.  3.2.2.1  Decomposition due to Oxidation Oxidation is a potential source of the “second distribution” of ions that needs to be  considered. Perhaps, the conditions for oxidation of the oligomers 3.8a to oxidized oligomers 3.9a with H 0 were too severe resulting in decomposition of the backbone. Therefore, another 2  sample of unoxidized oligomers 3.8a was prepared in an analogous fashion to that reported in  References start on page 72  55  Chapter 3  section 3.2.1; the exception being that after quenching the anionic oligomers 3.7a with MeOH, the terminated oligomers 3.8a were purified by precipitation under inert atmospheric conditions.  A sample for MALDI-TOF analysis was prepared using the layering method described above. From the mass spectrum, it was apparent that a mixture of oligomers was obtained with observable chain lengths of up to n  =  7. The masses of the oligomers were within experimental  accuracy (± 0.1%) of the calculated masses for protonated species (3.8a+H). Besides signals for linear species 3.8a and their isotopes, additional ions were observed in the spectrum. It is evident from Figure 3.3 that more than the unoxidized 3.8a ions are detected. Some of the additional peaks in the mass spectrum are assigned to partially oxidized oligomers. Unfortunately, the preparation of MALDI-TOF samples necessitates briefly exposure of the samples to air and therefore, partial oxidation of 3-coordinate phosphorus atoms was unavoidable. Consequently, ions that can be assigned to partially oxidized oligomers of 3.8a are observed in the spectrum in Figure 3.3 (see Table 3.2 and Table 3.3). Since the ions of the type 3.1Oa are indeed present in the spectrum, despite the brief exposure to air, oxidation seems an unlikely source of the “second distribution”.  References start on page 72  56  Chapter 3  a.i.  500  400  a 2 3.8  -  -  -  300 a 3 38 200  -  1001.  111i IL I I iL  1.] I  I  600  800  1000  a 4 3.8  idi. 11  a 5 3.8  1400  1600  •  I  1800  Figure 3.3  MALDI-TOF MS of oligomeric mixture 3.8a  Table 3.2  Selected MALDI-TOF MS data for oligomeric mixture 3.8a Calculated Found ) 1 n MW (g moF ) 1 MW (g moF 332.2 1 N/A 2 648.3 649 3 4 5 6 7  964.4 1280.6 1596.7 1912.9 2229.0  a 7 3.8  .i. I  I  I  1200  a 6 3.8  ilil,,  .  —I  2000  I  I  2200  m/z  967 1283 1598 1914 2231  References start on page 72  57  Chapter 3 Table 3.3  MALDI-TOF MS data for oligomeric mixture 3.8a with partially oxidized P atoms Calculated Found n MW (g moF ) 1 MW (g mor ) 1 2+0 664.3 666 2+20 680.3 682 3+0 980.4 981 3+20 996.4 997 3+30 1012.4 1015 4+0 1296.6 1297 4+20 1312.6 1314 4+30 1328.6 N/A 4+40 1344.6 N/A 5+0 1612.7 1615 5+20 1628.7 1631 5+30 1644.7 N/A 5+40 1660.7 N/A 5+50 N/A 1676.7 6+0 1928.9 1932 6+20 1944.9 1947 6+30 1960.9 N/A 6+40 1976.9 N/A 6+50 1992.9 N/A 6+60 N/A 2008.9  3.2.2.2  Backbiting At the beginning of these studies, only relatively high PDI’s were obtained for the  isolated polymers 3.2 (M  =  10 300 g mo1 1 vs polystyrene; PDI  =  1.55). If backbiting was a  competing pathway in the anionic polymerization mechanism, then the broad range of molecular weights and low yields  (Ca  30  —  40%) could be explained. 4 Backbiting reactions of the type  proposed below (Figure. 3.4) are uncommon in olefin polymerization. However, similar backbiting processes are very common in the anionic ring-opening polymerization of cyclic trisiloxanes 27 SiO) 2 [(R ] 3 2 ’ 8 . A backbiting mechanism necessitates the formation of cyclic oligomers (like 3.11 and 3.12). Close inspection of Figure 3.2 (inset A and B) show that ions are detected exactly 16 Da below 3.9a and 3.1Oa, respectively. A possible mechanism for their formation would involve nucleophilic attack of the backbone of a growing chain with its active end (carbanion). Attack of the chain can potentially occur at either a P or C atom. Attack on C would result in the formation of the cyclic 3.12 and the linear 3.1Oa after 2 0/H H 0 workup (see Figure 3.4). Conversely, the more likely attack at a P atom would result in the  References start on page 72  58  Chapter 3 formation of the cyclic 3.11 and the desired, though shorter, linear 3.9a. Ions that can be assigned to these cyclic species 3.11 and 3.12 are only observed up to n  =  5 for the MeLi  initiated oligomerization of MesP=CPh 2 (3.1).  Mes‘  Ph  ,  0/H H 0 2 +  Figure 3.4  Me{__c_j__H  3.7a 3.12 3.1Oa Proposed Mechanism of Backbiting of Propagating Oligomer 3.7a at a C Atom.  In order to test whether or not backbiting during oligomerization was indeed the cause of the “second distribution,” a number of experiments was devised: from varying the concentration of the oligomerizations to using different initiators and monomers. In the following subsections, these studies will be discussed along with their impact on the postulated mechanism of anionic oligomerization of P=C bonds.  3.2.2.2.1  Varying Reaction Conditions  The first means to test for backbiting was through varying the reaction conditions in order to evaluate the effects on the relative intensity of signals resulting from the postulated backbiting. For example, by increasing the monomer concentration for the oligomerization, the rate of backbiting should decrease because the probability of the reactive chain-end finding a monomer is greater. However, despite varying many reaction conditions (varying the concentration, reaction time, temperature, solvent and addition of coordinating ether 12-crown4), the “second distribution” attributed to 3.1Oa was continually observable in the MALDI-TOF MS. At very high concentrations of monomer (overall a —30 fold increase in concentration at 300 mg I 5 mL compared to 150 mg I 40 mL used originally to prepare 3.9a) in which little backbiting is expected to occur, there was evidence for the unwanted species 3.1Oa, 3.11, and 3.l2. In another trial, aliquots were removed at various times during the reaction that were References start on page 72  59  Chapter 3 analyzed by MALDI-TOF MS. After only two hours of reaction time, linear oligomers 3.9 a and 2  a were observable in the MALDI-TOF MS as was 3.10 3 3.9 a. It seems unlikely that short chains 2 of two or three repeat units could undergo backbiting due to the steric bulk of the chain.  The downside for using MeLi as the initiator is that the difference in MWs between the cyclic species (3.11) and linear species (39a) is 16 g moI 1 which corresponds to both the combined masses of the endgroups (Me and H) and the atomic mass of an 0 atom. It is possible that the ions assigned to the cyclic species are in fact under-oxidized linear oligomers. Using n-BuLi as the initiating species instead would separate the linear ions from the cyclic ions . 1 by 58 g mo1  3.2.2.2.2  Testing A Different Initiator: Preparing n-Bu[(Mes)P(=O)-CPh ]H, 3.9gb 2  A solution of n-BuLl was added to a stirred solution of phosphaalkene 3.1 in cold diethyl ether. After warming to room temperature, an aliquot was removed for analysis by 31 P NMR spectroscopy. A singlet resonance at —31.1 ppm was assigned to anionic 3.3b. To the reaction mixture was added a solution of 2 equivalents of phosphaalkene 3.2 in ether and stirred for 18 P NMR spectroscopy. The spectrum h. A second aliquot was removed and was analyzed by 31 showed a broad resonance at —5 ppm and no remaining phosphaalkene (ó  =  233) confirming  that the monomer 3.1 was consumed. To quench the reaction, a drop of water was added to the reaction mixture and resulted in a colour change from dark red to yellow. The product was oxidized by treating the reaction mixture in diethyl ether with H 0 in water. The ethereals were 2 removed in vacuo resulting in a pale yellow oil which was then dissolved in a minimal amount of CI The oligomeric mixture 3.9mb was isolated as a pale yellow powder from precipitation of CH . 2 CI solution into hexanes. The 31 CH the 2 P NMR spectrum of the powder dissolved in 2 CI CD showed a broad resonance at 48 ppm that is consistent with oxidized polymer 3.1 and Me initiated oligomers 3.9a. The MALDI-T0F MS sample was prepared in an analogous fashion as the samples for Me-initiated oligomeric mixtures 3.8a and 3.9a. References start on page 72  Chapter 3  60 n-BuLi “ Ph Et0 -78 °C  / Mes  10  Ph  Ph  1. 2 equiv. 3.1, Et 0 2  n-Bu—P—C—Li I I 2. H 0 or MeOH 2 Mes Ph 3. H0  —P—C—f--H 1 n-Bu—  I  I  I  LMeS PhJn  3.3b  3.1  Phi  3.9b  The MALDI-TOF MS shows that the anionic initiation of P=C bonds occurs with n-BuLi and the oligomerization proceeds in an analogous fashion to the Me-initiated oligomerization. Linear oligomers 3.9mb of up to 6 repeat units are detected (see Table 3.4 and Figure 3.5). Additionally, Na adducts of these linear oligomers are observed and are likely the consequence of washing 3.9b with brine during workup. Again, more ions are present in the mass spectrum than the predicted linear 3.9b. Potential backbiting products like the linear species 3.1 Ob with additional MesP=O moieties can be assigned to ions (n 1220.5 Da; n  =  4, MW  =  1552.6 Da; n  =  5, MW  =  =  2, MW  =  888.4 Da; n  =  3, MW  =  1884.8 Da). Most notable, however, is the  absence of ions that can be assigned to the cyclic species 3.12g. If backbiting were indeed occurring during oligomerization, and the backbiting attack occurred at the C atom in the backbone, the result would be both the presence of ions due to linear 3.1Ob as well as the cyclic 3.i2. Since cyclic species 3.12 are not observable, backbiting is likely not occurring to cause the presence of the “second distribution” assigned to 3.1 Ob. Additionally, when living anionic polymerization was later achieved by Kevin Noonan, the oligomerization was performed  under analogous conditions (n-BuLi as the initiator and glyme as the solvent) and found the presence of 3.1Ob in the MALDI-TOF MS. 29  30  The mounting evidence suggested that  backbiting is not the major contributor of ions assigned to the “second distributions” of 3.1Oa and 3.1Ob. To be certain, the range of the oligomerization was expanded to other similar phosphaalkenes. By tuning the electronic factors of these phosphaalkenes, the degree of backbiting if indeed any was occurring during oligomerization was hoped to be affected.  References start on page 72  61  Chapter 3 b 3 3.9  300  200 b 4 3.9 b 3 3.10  b 5 3.9  100  b+Na 4 3.9 b 4 3.10 b÷Na 5 3.9  1100  1300  1500  1700  b 6 3,9  1900  rnlz  Figure 3.5  MALDI-TOF MS of n-BuLi initiated oligomer mixture, 3.9mb  Table 3.4  Selected MALDI-TOF MS data for oligomeric mixture 3.9gb Calculated Found n MW (g moF ) 1 MW (g mor ) 1 1 390.2 N/A 2 722.4 722.8 (not shown) 1054.5 3 1056 4 1386.6 1388 5 1718.8 1721 6 2050.9 2053  3.2.2.2.3  Testing Different Phosphaalkenes: Preparation of Me[(Mes)P(=O)-CPhAr]H, 3.15a and 3.26a  The investigation of the oligomerization of other phosphaalkenes was explored, with the hope that by tuning the electronic factors of the monomers, backbiting could be either eliminated or enhanced. By adding an electron-withdrawing group in the para position of the aryl group, for example, it is expected to minimize backbiting due to the decreased nucleophilicity of the propagating chain. A weaker nucleophile is less likely to attack the bulky backbone resulting in little to no backbiting products. Alternatively, an electron-donating group would result in a more References start on page 72  62  Chapter 3 nucleophihc chain-end which would be more likely to attack the backbone thereby resulting in more backbiting products.  With a fluoro-containing phosphaalkene 3.13, it was hoped that only the linear oligomers Me[(Mes)P(=O)-CPhPhf]H 3.15a would be obtained. Phosphaalkene 3.13 was dissolved in diethyl ether and cooled to —80 °C. The solution was treated with MeLi and immediately darkened from yellow to orange. The reaction mixture was stirred while warming to room, whereupon, two additional equivalents of monomer 3.13 in diethyl ether were added at room temperature and the reaction mixture was stirred for 48 hours. Thereupon, water was added to 0 was used to oxidize the 2 the red reaction mixture whose colour immediately turned yellow. H oligomers. A yellow powder was isolated from the precipitation of the crude product mixture in a CI added to hexanes. A broad resonance at 35 ppm was observed in the CH small amount of 2 P NMR spectrum and assigned to the oxidized oligomeric mixture 3.15a. 31  MeL1 0, -78 °C 2 Ph Et  Mel 3.13  Me—p—C—Li  1.2 equiv 3.13, Et 0 2 HO  Mes Ph  2  3.14  2  Me—H  LMs  Ph  3.15a  Analysis of the precipitated product by MALDI-TOF MS showed evidence of up to only 3 linear repeat units of fluorinated oligomers 3.15a (n  =  1 —3) (see Figure 3.6 and Table 3.5).  Electron-withdrawing groups on the phenyl substituent appeared to slow the oligomerization. Consumption of the monomer was not complete after two days. In contrast, the oligomerization of MesP=CPh 3.1 requires only 18 h. By 31 2 P NMR spectroscopy, oligomerization of fluoro containing 3.13 appeared to stop despite the presence of monomer in solution. Incidentally, inclusion of a second fluorine substituent in a similar phosphaalkene monomer 3.16 resulted in no evidence of oligomerization with substoichiometric amounts of MeLi (see Scheme 3.2). Contrary to predictions, F-containing monomers did not enhance oligomerization and, in fact, References start on page 72  63  Chapter 3 resulted in more ions assigned to the “second distribution” than the desired linear oligomers 3.15a. With these confusing results of using an electron-donating phosphaalkene, the oligomerization of an electron-withdrawing containing phosphaalkene was investigated.  F  F  (S  iD=c’03 equiv MeLi / THF,-78°C ?\ \ Mes  3.16  3.17  Scheme 3.2  ro I ii  An  LMes  PhJ Mes  Q II Me-I—P—c j_P_H  I  I  3.18a Ar  =  F 4 H 6 p-C  3.21 a Ar  =  OMe 4 H 6 p-C  0 r  1 Ar  lMeh 3.19 Ar 3.22 Ar  o  An Ar II H I p —c--i-—c I  I  II  Mes PhJPh  =  F 4 H 6 p-c  3.2O  Ar  =  F 4 H 6 p-c  =  OMe 4 H 6 p-C  3.23  Ar  =  OMe 4 H 6 p-c  References start on page 72  64  Chapter 3  a.i.  -  a 2 3.18  20000-  15000-  a 2 3.15  10000-  a 1 318 a 1 315  5000-  a 2 3.19 .  LILIILi  I  •  400  I  •  I  I  600  L  a 3 315 2 O 2JL_  •  800  1000  Figure 3.6  MALDI-TOF MS of the oligomeric mixture 3.15a  Table 3.5  Selected MALDI-TOF MS data for oligomeric mixture 3.15a Calculated Found ) 1 n MW (g mor ) MW (g mor 1 1 366.2 367.0 2 716.3 717.0 3 1066.4 1067  mlz  The preparation of oligomers with electron-donating groups (OMe) was performed similarly to the oligomerizations reported above. One equivalent of the initiator MeLi in ether was added to a solution of phosphaalkene 3.24 in diethyl ether at —80 °C and the mixture was warmed to room temperature while being stirred. 31 P NMR spectroscopy was used to analyze an aliquot taken from the reaction mixture (ö  =  —43). The reaction mixture was treated with a  solution of 2 equivalents of methoxy-containing 3.24 in diethyl ether and was stirred overnight. The reaction mixture was quenched with water and oxidized with H 0 afforded oligomers 2 3.25a that were purified by precipitation from a concentrated solution of 3.26a in 2 CI into CH hexanes. The precipitated product was a yellow powder. References start on page 72  65  Chapter 3  MeLi / Mes  “  Ph EtO, -78 °C  3.24  OMe  OMe  OMe  Me—Li  I  I  Mes Ph 3.25  1 2 equiv 3.24, Et 0 2 2. H 0 2 .  MeH  I  I  I  I  LMes Ph J, 3.26a  P NMR spectroscopy of a solution of oligomeric mixture 3.26a in 2 31 CI showed a CH characteristic broad resonance at 40 ppm akin to other oligomeric mixtures. MALDI-TOF MS revealed that linear oligomers with up to 5 monomer units were obtained (see Figure 3.7 and Table 3.6). Notably, the presence of the “second distribution” of linear oligomers 3.21a exists in the MS albeit at smaller relative concentrations to the desired 3.26a. In this case, the nucleophilicity of the propagating chain was greater than for that of MesP=CPh 2 3.1. Therefore, relatively higher concentrations of backbiting ions (3.21a, 3.22a and 3.23a) were expected in the spectrum. Regardless of the changes I made to the reaction, the “second distribution” always appeared in the spectra.  References start on page 72  Chapter 3  66  ai 200  150  100  a 3 3.21  50  II]  -,.‘.--1 rF  700  Ii  “‘I’!  Wj”  900  1100  1300  1500  1700  Figure 3.7  MALDI-TOF MS for oligomeric mixture 3.26a  Table 3.6  Selected MALDI-TOF MS data for oligomeric mixture 3.26a Calculated Found n MW (g moF ) MW (g mor 1 ) 1 1 378.2 N/A 2 3  4 5  740.3 1102.5 1464.6 1826.8  m!z  741.3 1104 1466 1828  The mounting evidence that backbiting could not be the cause of the second distribution is obvious. Though initially disappointing, having backbiting not occur at ambient temperature during propagation means that strict control over polymer structure is possible. In fact, it was later shown that phosphaalkene 3.1 can be anionically polymerized in a living fashion. 29 The ultimate explanation for the presence of these “second distribution” of ions is possibly fragmentation during ionization.  References start on page 72  Chapter 3 3.2.2.3  67 Fragmentation  Fragmentation of oligomers like 3.9a is possible. However, it is relatively uncommon in polymer MALDI-TOF mass spectrometry. 31 If the P—C chains are easily fragmented during ionization, ions like 3.1Oa could be accounted for. However, if fragmentation during ionization is facile, it is expected that oligomeric fragments in attempted MALDI-TOF MS analysis of polymer 3.2 would be observed. Under analogous MALDI conditions, species in mass spectra for the low MW polymer 3.2 (GPC M  =  5 x  to 1 x  io g mor ) were not observed at all. 1  In addition,  oxidized 3.2 is thermally stable up to 320 °C as determined by TGA which seems to suggest a stable backbone that is not likely to fragment easily. Since oxidation and backbiting were eventually ruled out as being sources of the “second distribution”, fragmentation was investigated.  Some rudimentary MALDI-TOF experiments were performed on Me-initiated oligomers 3.9a. The best spectra (i.e. best resolution and intensities) were acquired while using 2,5dihydroxybenzoic acid as the matrix, other common matrices were tested (cinnaminic acid, dithranol and anthracenetriol). In every case, the “second distribution” of ions was observed. Based on the observations, the source of the “second distribution” may possibly be, albeit unexpected, the fragmentation of ions of 3.9a to give 3.1Oa.  3.3  Conclusion  Our previous work on the polymerization of phosphaalkene 3.1 with MeLi (5%) in a minimum of solvent required a temperature of 150  4 0C  This work demonstrated that chain  growth proceeds in solution without heating and the observation of endgroups supports that the proposed mechanism of anionic polymerization for P=C bonds is analogous to that for olefins. Anionic oligomerization of phosphaalkenes can be extended to the use of another initiator (n BuLi) and to other monomers with functional groups (F and OMe). The oligomers were mainly References start on page 72  Chapter 3  68  characterized by MALDI-TOF MS and were found to have the proposed linear structure with up to 11 repeat units. However, based on the information at present, a possible source of the “second distribution” is the fragmentation of linear oligomers.  3.4  3.4.1  Experimental  Materials and General Procedures All manipulations of oxygen- and/or moisture-sensitive compounds were performed  under a nitrogen atmosphere using standard Schlenk and/or glovebox techniques. Hexanes, diethyl ether and dichloromethane were deoxygenated with nitrogen and dried by passing through a column containing activated alumina. THF was freshly distilled from sodium/benzophenone ketyl. Distilled water and methanol were degassed prior to use. CDCI 3 was distilled from P 5 and degassed. 2 0 2 CI and C CD D were purchased from Cambridge 6 Isotope Laboratories and were dried over molecular sieves (3 A). MeLi (1.6 M in Et 0), n-BuLi 2 (1.6 M in hexanes) were purchased from Aldrich and used as received. Alkyllithium reagents were titrated prior to use. MesP=CPh , MesP=CPh(p-C 2 F), and MesP=CPh(p-C 4 H 6 OMe) 4 H 6 were prepared following literature procedures. 32  P, 1 31 H and 13 H} NMR spectra were recorded on BrukerAV300 orAV400 1 C{ spectrometers at room temperature. Chemical shifts for 31 P NMR spectra are reported relative to 4 P0 as an external standard (85% in H 3 H 0, ö 2 are reported relative to 2 CI (ó CD  =  =  0). Chemical shifts for 13 H} NMR spectra 1 C{  3 (ô 54.0) or CDCI  spectra are reported relative to residual CHDCI 2 (8  =  =  77.2). Chemical shifts for 1 H NMR  5.32) or CHCI 3 (8  =  7.27) or 5 HD (8 6 C  =  7.16).  The MALDI-TOF spectra were acquired using a Bruker Biflex IV spectrometer. The samples were dissolved in 2 CI and deposited on the sample target with a layer of matrix CH  References start on page 72  Chapter 3  69  previously deposited. The matrix, 2,5-dihydroxybenzoic acid, was dissolved in THF. The measurements were performed using the following conditions: positive polarity, reflection flight path, 18kV acceleration voltage, 20 shots per sample. Insulin Chain B, bovine insulin (oxidized) and Angiotensin II, human synthetic were obtained from Sigma-Aldrich and used as standards. I would like to thank Dr. Yun Ling and Marshall Lapawa for assistance in troubleshooting while using the MALDI-TOF MS.  3.4.2  Preparation of Me[MesP-CPh ]H, 3.8a 2 To a stirred solution of mesityl(diphenylmethylene)phosphine 3.1 (0.050 g, 0.16 mmcl)  dissolved in diethyl ether (20 mL) at -78°C was added 1.5 M methyllithium in diethylether (0.13 mL, 0.19 mmol). After warming to room temperature, an aliquot was removed and analyzed by P NMR spectroscopy (Mes(Me)P-CPh 31 Li, ó 2  =  -45 ppm). A solution of 1(0.10 g, 0.32 mmol)  dissolved in diethyl ether (20 mL) was added slowly to the reaction mixture. After being stirred for 24 hours, the reaction was quenched with degassed water. Analysis of an aliquot by 31 P NMR spectroscopy showed a broad resonance centered at —5 ppm like the polymer 3.2. The solvent was removed in vacuo leaving a dark yellow oil. The oil was dissolved in a small amount of dichloromethane. The resulting solution was added to hexanes whereupon the oligomers precipitated as a yellow solid. Yield  =  0.09 g (60%).  p NMR 2 31 CI 121.5 MHz): ô (CD ,  =  —7 (br); 1 H NMR 2 CI 300 MHz): ô (CD ,  =  7.7  —  6.7 (br,  aryl), 2.5—1.8 (br, alkyl); 13 H} NMR (CDCI 1 C{ , 75.5 MHz): 146.7 (br, Mes), 143.2 (br, Mes), 3 138.2 (br, Mes), 132-1 25 (br mult, Ph), 52.0 (br, P-C-P), 22.9 (br, o-CH ), 20.9 (br, p-CH 3 ). 3  3.4.3  Preparation of Me[MesP(=O)-CPh ]H, 3.9a 2 The preparation was analogous to that of 3.8a except that 3 equivalents of  phosphaalkene 3.1 was added to the Mes(Me)P—CPh Li solution. Once the unoxidized 2 oligomeric mixture 6a was isolated, To the oil was added dichloromethane (10 mL) and the  References start on page 72  Chapter 3  70  suspension was filtered then oxidized with 30% H 0 for 30 mm. The organic layer was washed 2 twice with water and dried over magnesium sulphate. The solvent was removed in vacuo leaving a pale yellow oil. The oil was dissolved in a small amount of dichloromethane and precipitated from hexanes leaving a pale yellow solid. Yield  p NMR 2 31 CI 121.5 MHz): ó (CD , aryl), 3.7  3.4.4  —  =  =  0.11 g (54%).  46 (br); 1 H NMR 2 CI 300 MHz): (CD ,  =  7.6—6.6 (br,  1.5 (b, alkyl).  Preparation of Bu[MesP(=O)-CPh ]H, 3.9mb 2 Prepared analogously to 7a, but with an overall ratio of phosphaalkene:n-BuLi of 2:1  rather than 4:1 above. The product is a yellow solid. Yield  p NMR 2 31 CI 121.5 MHz): ô (CD ,  =  =  0.11 g (73%).  48 (br); 1 H NMR 2 CI 300 MHz): ó (CD ,  aryl), 3.7—1.5 (b, alkyl); 13 H} NMR 2 1 C{ CI 100.6 MHz): ô (CD , 129.5  (5),  128.7 (s), 127.1 (d, 4 Jc’  =  2 Hz, rn-Ph-C), 126.5 (d,  =  =  7.6—6.6 (b,  143.6 (s), 143.4 (s), 130.2 (s),  Jcp = 4  2 Hz, rn-Ph-C), 50.6 (bs),  30.2 (bs), 24.7 (bs), 21.2 (s), 15.1 (s).  3.4.5  Preparation of Me[MesP(=O)-CPh(p-C F)]H, 3.15a 4 H 6 To a cooled (—78°C) solution of fluoro-substituted phosphaalkene 14(0.10 g, 0.30 mmcl)  in diethyl ether (10 mL) was added MeLi in Et 0 (0.24 mL, 1.5 M, 0.36 mmol). Upon addition, 2 there was an immediate colour change from yellow to dark red. The cooled solution was stirred for 1 h and then warmed to room temperature. To the solution was added 2 equivalents of phosphaalkene 14 (0.20 g, 0.60 mmol) in 30 mL of diethyl ether. The reaction mixture was stirred for 48 h whereupon degassed MeOH (0.4 mL) was added. From the resulting colourless solution, THF was removed in vacuo affording a yellow solid residue. The soluble fraction was extracted into diethyl ether (3  x  10 mL) and the resulting solution was stirred with H 0 (30% in 2  0). The organic layer was isolated and dried over Mg SO 2 H . The solvent was evaporated to 4 References start on page 72  71  Chapter 3 dryness affording a yellow solid. The mixture was purified by precipitation from a concentrated solution of 2 CI added to hexanes. Yield: 0.07 g (24 %). CH  CI 121.5 MHz): (CD , H} NMR 2 1 P{ 31  =  H NMR 2 CI 300 MHz): ó (CD , 35 (br); 1  =  7.0 (b,  aryl), 2.5—1.3 (br, alkyl); 13 H} NMR (CDCI 1 C{ , 75.5 MHz): 163.4 (br, p-Ar), 159.9 (br, p-Ar), 3 142-1 25 (br mult, Ar), 115.1 (br, rn-Ar), 55.0 (br, P—C—P), 24.7 (br, o-CH ), 20.9 (br, p-CH 3 ). 3  346  Preparation of Me[MesP(O)-CPh(p-C OMe)]H, 3.26a 4 H 6 To a cooled (—78°C) solution of methoxy-substituted phosphaalkene 18 (0.05 g, 0.14  mmol) in diethyl ether (5 mL) was added MeLi in Et 0 (0.15 mL, 1.5 M, 0.17 mmol). Upon 2 addition, there was an immediate colour change from yellow to dark red. The cooled solution was stirred for 1 h and then warmed to room temperature. To the solution was added 2 equivalents of phosphaalkene 18(0.10 g, 0.28 mmol) in 15 mL of THE. The reaction mixture was stirred for 18 h whereupon degassed MeOH (0.4 mL) was added. From the resultant colourless solution, THF was removed in vacuo affording a yellow solid residue. The soluble fraction was extracted into diethyl ether (3 x 10 mL) and the resulting solution was stirred with 0 (30% in H 2 H 0). The organic layer was isolated and dried over MgSO 2 . The solvent was 4 evaporated to dryness affording a yellow solid. The mixture was purified by precipitation from a concentrated solution of 2 CI added to hexanes 3 times. Yield: 0.09 g (70 %). CH  H} NMR 2 1 P{ 31 CI 121.5 MHz): ó (CD ,  =  40 (br); 1 H NMR 2 CI 300 MHz): ó (CD ,  7.2—6.7  (br, aryl), 3.7 (br, -OCH ), 2.7 — 1 .3 (br, alkyl). 3  References start on page 72  Chapter 3 3.5  72  References  1. F. Mathey. Angew. Chem.  mt.  Ed. 2003, 42, 1578.  2. K. B. Dillon, F. Mathey, J. F. Nixon, Phosphorus: The Carbon Copy. Wiley: West Sussex, 1998. 3. M. Yoshifuji. J. Chem. Soc., Dalton. Trans. 1998, 3343. 4. C.-W. Tsang, M. Yam, D. P. Gates. J. Am. Chem. Soc. 2003, 125, 1480. 5. B. H. Gillon, K. J. T. Noonan, B. Feldscher, J. M. Wissenz, Z. M. Kam, T. Hsieh, J. J. Kingsley, J. I. Bates, D. P. Gates. Can. J. Chem. 2007, 85, 1045. 6. B.-L. Li, R. H. Neilson. inorg. Chem. 1984, 23, 3665. 7. A. Mack, U. BergstraBer, G. J. ReiB, M. Regitz. Eur. J. Org. Chem. 1999, 587. 8. M. Schmitz, S. Leininger, U. Bergstrasser, M. Regitz. Heteroat. Chem. 1998, 9, 453. 9. T. Wettling, J. Schneider, C. G. Kreiter, M. Regitz. Angew. Chem.  mt.  Ed. EngI. 1989, 28,  1013. 10. R. Bartsch, P. B. Hitchcock, J. F. Nixon. J. Chem. Soc., Chem. Commun. 1989, 1046. 11. V. Caliman, P. B. Hitchcock, J. F. Nixon, M. Hofmann, P. v. R. Schleyer. Angew. Chem. mt. Ed. EngI. 1994, 33, 2202. 12. F. Tabellion, A. Nachbauer, S. Leininger, C. Peters, F. Preuss, M. Regitz. Angew. Chem.  mt.  Ed. 1998, 37, 1233.  13. D. A. Loy, G. M. Jamison, M. D. McClain, T. M. Alam. J. Polym. Sd., Part A: Polym. Chem. 1999, 37, 129. 14. A. M. Arif, A. R. Barron, A. H. Cowley, S. W. Hall. J. Chem. Soc., Chem. Commun. 1988, 171. 15. M. Yoshifuji, H. Sugiyama, S. Ito. J. Organomet. Chem. 2005, 690, 2515. 16. M. Y. He, H. Chen. Curr. Org. Chem. 2007, 11, 909. 17. G. Montaudo, F. Samperi, M. S. Montaudo. Prog. Polym. Sd. 2006, 31, 277. 18. C. Barner-Kowollik, T. P. Davis, M. H. Stenzel. Polymer 2004, 45, 7791. References start on page 72  Chapter 3  73  19. S. F. Macha, P. A. Limbach. Curr. Opin. Solid State Mater. Sci. 2002, 6, 213. 20. M. J. Stump, R. C. Fleming, W. H. Gong, A. J. Jaber, J. J. Jones, C. W. Surber, C. L. Wilkins. App!. Spectrosc. Rev. 2002, 37, 275. 21. S. D. Hanton. Chem. Rev. 2001, 101, 527. 22. H. R. Allcock, C. R. de Denus, R. Prange, W. R. Laredo. Macromolecules 2001, 34, 2757. 23. B. M. White, W. P. Watson, E. E. Barthelme, H. W. Beckham. Macromolecules 2002, 35, 5345. 24. F. H. KOhIer, A. Schell, B. Weber. Chem. Eur. J. 2002, 8, 5219. 25. J. C. Blais, C. 0. Turrin, A. M. Caminade, J. P. Majoral. Anal. Chem. 2000, 72, 5097. 26. V. Marvaud, D. Astruc, E. Leize, A. Van Dorsselaer, J. Guittard, J. C. Blais. NewJ. Chem. 1997, 21, 1309. 27. M. Barrère, C. Maitre, M. A. Dourges, P. Hémery. Macromolecules 2001, 34, 7276. 28. J. Libiszowski, A. Kowaiski, R. Szymanski, A. Duda, J. M. Raquez, P. Degee, P. Dubois. Macromolecules 2004, 37, 52. 29. K. J. T. Noonan, D. P. Gates. Angew. Chem. lnt. Ed. 2006, 45, 7271. 30. K. J. T. Noonan, B. 0. Patrick, D. P. Gates. Chem. Commun. 2007, 3658. 31. H. J. Räder, W. Schrepp. Acta Polym. 1998, 49, 272. 32. M. Yam, J. H. Chong, C.-W. Tsang, B. 0. Patrick, A. E. Lam, D. P. Gates. lnorg. Chem. 2006, 45, 5225.  References start on page 72  74  Chapter4  The Coordination Chemistry of PoIy(methylenephosphine)s with Tungsten, Molybdenum, and Chromium*  4.1 Introduction  Metal-containing polymers have garnered interest from scientists due to their interesting 18 For example, macromolecules with metal species dangling from a polymer side properties. chain have found uses as supported catalysts because they simplify the separation of the metal from the desired organic products. One route to these types of macromolecules is through functionalization of existing polymers. For organic polymers, often functional groups (like phosphines) are attached in multiple steps allowing for a potential coordination site for the metal 9 A typical approach (see Scheme 4.1) involves polymerization of 4-bromostyrene atoms. followed by a lithiation, then a reaction with chlorodiphenylphosphine. ° Metal coordination to 1 the supported phosphine can occur through a phosphine substitution reaction. 11 Derivatizations of polymers, though sometimes simple, can be complicated due to the fact that polymers are notoriously difficult to characterize compared to molecular species. If the polymer backbone were to contain a phosphine, then metallation could be attained with a one-step, classic coordination chemistry reaction.  * A portion of this chapter will be published shortly. Bronwyn H. Gillon, Tom Hsieh and D. P. Gates, “Metallation of Poly(methylenephosphine)s with Group 6 Metal Carbonyls.”  References start on page 99  Chapter 4  75  2 CIPPh Br  2 PPh  Scheme 4.1  Some time ago, we reported the polymerization of P=C bonds to yield phosphoruscontaining polymers 4.2. With the three-coordinate phosphorus built into the backbone,  poly(methylenephosphine)s 4.2 is an obvious candidate for coordination chemistry, with potential uses for catalysis. Recently, Tsang et a!. showed that Suzuki cross-coupling reactions between bromobenzene and phenylboronic acid were possible in the presence of a phosphine containing copolymer 4.3, indicative of an interaction between the active catalyst, Pd(0), and the polymer (see Scheme  4.2).12  The interactions between metals and homopolymer 4.2 were  explored.  Ph Me  E  initiator  —c  Ph  Phi  LMsl’h]n  4.1  4.2  5-10 mol % Ph  /rHH  Il  I  I  —H-C-CI II  [  +  I  ..  \  H Ph ‘  I  P-C I MesPh  1.5 5 mcI % 3 dba 2 Pd 3.3 equivsCsF  THE  Scheme 4.2 Since characterizing and functionalizing macromolecules can be challenging, a couple of strategies were devised to overcome these difficulties while showing that P-M bonds can be  References start on page 100  Chapter 4  76  formed with poly(methylenephosphine)s. First, Group 6 metal carbonyls, M(CO) , were 6 selected since they are well known to undergo substitution reactions with phosphine ligands. ’ 13 14  Additionally, the carbonyl ligands provide a distinct IR handle which should simplify  characterization. Secondly, a small molecule  4•41517  was prepared in order to model the  homopolymer 4.2 to gain insight into the reactivity of the backbone phosphines towards the Group 6 metals. If high metal content is achieved, particularly with tungsten and molybdenum, we could have access to interesting metal phosphide materials useful for hydroprocessing, for example. 19 ’ 18  4.2  4.2.1  Results and Discussion  Model Compound Reactions  M 5 (CO) Ph Me-P—C—H I I Mes Ph 4.4  f  Ph Me-P—C—H I Mes Ph M=W 4.5a Mo 4.5b Cr 4.5c  6 M(CO)  4.2.1.1 Coordination of Model Compound 4.4 to Tungsten Initial attempts to synthesize 4.5a photochemically using UV radiation proved difficult with multiple side reactions being 20 observed. 2 ’ 1 The thermal preparation of tungsten phosphine complexes was reported by Magee et al. and proved more fruitful. 13 A mixture of 4.4 and 6 in diglyme was stirred at 160 °C for 4 hours. The reaction was monitored by 31 W(CO) H} 1 P{ NMR spectroscopy noting the disappearance of 4.4 (ó resonance with 183 W satellites (6  =  7.9 ppm, 1 Jpw  =  crystals were grown from an ethanol solution (yield  =  -23 ppm) and the emergence of a  236.3 Hz) assigned to 4.5a. X-ray quality =  20%) to afford colourless, moderately air-  References start on page 100  Chapter 4  77  stable crystals. The molecular structure was confirmed by 31 P, 13 C, 1 H NMR spectroscopy; FT-IR spectroscopy; EA; low resolution El MS (M, m/z  =  656); and x-ray crystallography.  -  Figure 4.1  10 20 -10 -20 -30 ppm H} NMR spectra (diglyme) of: (a) model compound 4.4 and (b) tungsten 1 P{ 31 adduct 4.5a.  The 1 H NMR spectrum for tungsten adduct 4.5a, is similar to that of the model compound 4.4, though the resonances are generally shifted slightly downfield. For example, in 2 CI the CD , benzylic proton (CHPh ) in the model compound 4.4 results in a resonance at 4.87 ppm, but the 2 analogous proton in the tungsten adduct 4.5a resonates at 5.22 ppm. The most notable difference is that upon coordination, the two ortho-methyl groups on the mesityl become magnetically inequivalent and show two separate resonances (broad signals at  =  2.4 and 2.8  ppm). If rotation about the P(1)-C(1) bond were restricted, the methyl groups would be in different environments since the P atom is a stereogenic center.  The most notable features in the 13 C NMR spectrum are resonances due to the carbonyl ligands. The carbonyl trans to the phosphine shows a doublet at 202.2 ppm with a relatively large coupling constant ( Jcp 2  =  22.1 Hz). The cis carbonyls show a doublet at 199.8 ppm ( Jcp 2  =  References start on page 100  Chapter 4  78  6.4 Hz) with W satellites ( Jcw = 127.1 Hz). The resonances due to the phosphine ligand are 1 similar to those of the free phosphine 4.4.  The solid-state molecular structure of 4.5a shows that two of the P-C bonds (P(l)-C(l) and P(1)-C(1O))areslightlyshortened; 1.848Aand 1.831 A(cf 1.852Aand 1.840A) , 17 respectively. Notably, the other P-C bond (P(1)-C(1 1)) has lengthened from 1.882 (1) A to 1 .915 (2) A upon coordination. The lengthening of this bond is, presumably, reflected in the mass spectrum with 2 of the 3 most intense fragment signals corresponding to fragments formed from the breaking of the P(1)-C(11) bond (M  =  167 and 489 m/z). The lengthening of  the P(1)-C(11) bond could become a problem for the coordination of the polymer to tungsten. That bond corresponds to the P-C bonds in the polymer backbone. If the backbone bonds are weakened, it is possible that coordination could lead to polymer degradation. This important insight from the solid-state molecular structure will be discussed later for the coordinated polymers.  References start on page 100  Chapter 4  79  C3  i9  C20 022 C21  Figure 4.2  Solid-state molecular structure of the tungsten-model adduct 4.5a (50% probability ellipsoids). Hydrogen atoms are omitted for clarity. Selected bond lengths (A): P(1)-C(1) = 1.848(2); P(1)-C(10) 1.831(2); P(1)-C(11) = 1.915(2); P(1 )-W(1) = 2.5621(5); C(24)-W(1): 2.030(2); C(25)-W(1): 2.060(2); C(26)-W(1): 1.996(2); C(27)-W(1): 2.040(2); C(28)-W(1): 2.034(2). Selected bond angles (°):C(1 0)-P(1)-C(1)= 110.82(9); C(1 0)-P(1)-C(1 1) = 99.75(9); C(1)-P(1)-C(1 1) = 101 .49(8); C(10)-P(1)-W(1) = 109.02(6); C(1)-P(1)-W(1) = 11.43(6); C(11)-P(1)W(1) = 123.49(6). Geometry about W atom is nearly octahedral.  4.2.1.2 Coordination of Model Compound 4.4 to Molybdenum The synthesis of 4.5b is analogous to that of the tungsten adduct 4.5a except that the reaction proceeds in THE at reflux for 20 hours. The reaction was monitored by 31 P{’H} NMR spectroscopy with the observance of the appearance of a resonance at 28 ppm assigned to the complex 4.5b. X-ray quality crystals are grown from a concentrated ethanol solution to afford colourless, slightly air-stable crystals (yield  =  63%). The identity of the compound was  confirmed by 31 P, 13 C, ‘H NMR spectroscopy; FT-IR spectroscopy; EA; low resolution El MS (M, mlz  =  572); and x-ray crystallography.  Coordination to molybdenum has very little effect on the ‘H NMR spectrum of the phosphine. Like the tungsten-adduct, resonances for the protons of the phosphine are shifted References start on page 100  Chapter 4  80  downfield slightly when compared to the free phosphine; the doublet due to the benzylic proton (CHPh ) is found at 5.06 ppm where 2  JPH = 2  6.9 Hz. Also, the two ortho-methyl groups on  the mesityl are not magnetically equivalent resulting in two broad signals at ó  =  2.66 and 2.15  ppm.  The molecular structure of molybdenum adduct 4.5b shows that two of the P-C bonds (P(1)-C(1) at 1.847(2) and P(1)-C(10) at 1.830(2)) are statistically equivalent to the analogous W-adduct 4.5a bonds; 1.848(2) and 1.831 (2) A, respectively. The P(1)-C(11) bond, however, is slightly shorter at 1.907(2) A. It is possible, that coordination of Mo(CO) 5 moiety could have less impact on the stability of the polymer than the tungsten analogue making Mo a better candidate for metallation. The ‘backbone’ P-C bond in Mo-adduct 4.5b is still longer than the free phosphine 4.4 (1.882 A). However, the most intense signal in the El mass spectrum is the W fragment (M 2 CPh  =  167 mlz).  References start on page 100  Chapter 4  81  C14 013  022 021  Figure 4.3  Solid-state molecular structure of the molybdenum-model adduct 4.5b (50% probability ellipsoids). Hydrogen atoms are omitted for clarity. Selected bond lengths (A): P(1)-C(1) = 1.847(2); P(1)-C(10) = 1.830(2); P(1)-C(11) = 1.907(2); P(1)-Mo(1) = 2.562(1); C(24)-Mo(1) = 1.981 (3); C(25)-Mo(1) = 2.061 (2); C(26)Mo(1) = 2.029(3); C(27)-Mo(1) = 2.043(3); C(28)-Mo(1) = 2.027(2). Selected bond angles (°): C(1)-P(1)-C(10) = 110.6(1); C(1)-P(1)-C(11) = 101.34(9); C(10)P(1)-C(11) = 99.6(1); C(1)-P(1)-Mo(1) = 111.46(8); C(10)-P(1)-Mo(1) = 109.06(8); C(11)-P(1)-Mo(1) = 123.82(6). Geometry about Mo atom is nearly octahedral.  4.2.1.3 Coordination of Model Compound 4.4 to Chromium 6 in glyme was stirred at 120 °C for 5 days. The reaction A mixture of 4.4 and Cr(CO) was monitored with 31 H} NMR spectroscopy by the disappearance of 4.4 (ó 1 P{ the emergence of a resonance  =  -23 ppm) and  ( = 49.6 ppm) assigned to 4.5c. Unfortunately, X-ray quality  crystals were never isolated. The molecular structure was confirmed by 31 H NMR P, 13 C, 1 spectroscopy; FT-IR spectroscopy; and low resolution El MS (Mt, mlz  =  524). The 1 H NMR  spectrum for 4.5c is similar to those of 4.5a and 4.5b. The ortho-methyl groups of the mesityl are inequivalent and broadened (ô  =  2.4 and 2.8 ppm). Having successfully prepared the model  compounds, we were determined to coordinate the polymer to M(CO) 5 moieties utilizing the thermal method. References start on page 100  Chapter 4  4.2.2  82  Thermal Stability of Poly(methylenephosphine) 4.2 in Solution Since the preparation of adduct 4.5a required somewhat high temperatures (-160 °C),  we were concerned that the polymer 4.2 may decompose under similarly harsh conditions. Therefore, we wanted to test the resiliency of the homopolymer 4.2 to high temperatures. We were hopeful that no significant decomposition would occur because TGA analysis demonstrated that, as a solid, polymer 4.2 does not decompose significantly until approximately 265  OCiG  In order to evaluate the solution stability of poly(methylenephosphine)s 4.2 to heat, samples of 4.2 were refluxed in a number of solvents for varying amounts of time. The polymer was then be precipitated once from a concentrated solution of 2 CI into hexanes, dried in CH vacuo and then characterized by triple detection GPC. The results are summarized in Table 4.1. Homopolymer 4.2 can withstand temperatures of up to 110°C in ethereal solvents for approximately one week without an appreciable decrease in M and is recoverable in high yields (see samples 1 and 3). After a few weeks, a small amount of polymer decomposition occurs in refluxing glyme (sample 4). However, in THE, the polymer remains intact after 24 days. Therefore, since refluxing in THF or glyme does not appear to break down the structure of the polymer 4.2, heating is a viable route to coordinating the chromium and molybdenum carbonyls to the polymer. However, upon heating in diglyme at 160°C, the polymer degrades into a brown solid after just 18 hours (sample 6). If the reaction mixture is removed from the heat source after just 4 hours, the polymer maintains its structural integrity, as its M does not significantly decrease. As a result, to coordinate the tungsten carbonyl moiety, a short reaction time is imperative.  References stan’ on page 100  Chapter 4  83  Table 4.1 Studies on the Thermal Stability of Poly(methylenephosphine) 4.2 in Solution. )/PDl 1 M(qmoi Sample 1 2 3 4 5 6  4.2.3  Solvent THF THF glyme glyme diglyme diglyme  Temp. (°C) 70 70 100 100 160 160  Time 6 days 24 days 6 days 24 days 4h 18h  Before heating 28 000 I 1.14 54300/ 1.10 54 300 / 1 10 54 300 / 1.10 21 800/1.3 21 800/1.3  After heating 28 600 I 1.11 54350? 1.19 50 200 I 1.32 45 500 / 1.19 20 200/1.26 bimodal  % Reco vered 92 87 69 87 65 70  Colour yellow yellow yellow yellow yellow brown  Preparation of Group 6 Metal-Containing PoIy(methylenephosphine)s We chose Group 6 metals carbonyls, M(CO) , to coordinate to the phosphine-containing 6  polymer 4.2 as a proof of concept; the polymer will behave like a phosphine and form complexes with metals. Moreover, we expected that characterization of a metallated polymer might be difficult. Metal carbonyls have the exploitable IR handle. Carbonyls have strong C—O stretches in the 1900  —  1 region. The frequency of the stretch of a carbonyl is also very 2000 cm  sensitive to the nature of the ligand in the trans position. Therefore, FTIR will give us conclusive evidence of a phosphorus-metal bond. However, the greatest disadvantage of metallating with  5 fragments is their size and the close proximity of P atoms in the polymer backbone. M(CO) Complete functionalization of polymer 4.2 into metallated polymers 4.6a-c will likely be impossible due to steric effects. The most probable metal-containing products will be random copolymers of the type 4.7a-c.  F Phi Mej-P-C-f H LMesPh]n  r  5 M(CO)  Phi Mej-P-C-fH  6 M(CO) A  LMesPh]n  4.2  M=W 4.6a Mo 4.6b Cr 4.6c 5 M(CO)  [  Ph Mel—P-C \  LMsTh x+y  fPhl P—C4H MesPhjy  1 M=W 4.7a Mo 4.7b Cr 4.7c =  References start on page 100  Chapter 4  84  4.2.3.1 Coordination of Poly(methylenephosphine) 4.2 to Tungsten Given that the coordination of the model compound 4.4 to tungsten ran smoothly under thermal conditions, we set out to emulate the complexation using poly(methylenephosphine) 4.2. The thermal stability studies (section 4.2.2) showed that polymer 4.2 decomposes in solution at high temperature (160°C) after more than 4 hours. Therefore, the polymer should not be exposed to such conditions in diglyme for more than a few hours.  A flask equipped with a Teflon valve was loaded with poly(methylenephosphine) 4.2, an excess of W(CO) , and diglyme. After three freeze-pump-thaw cycles, the reaction mixture was 6 heated to 160 °C while protected from light. After 4 hours, the reaction mixture turned from a light yellow solution to a brown suspension with black flakes. The solution was added to a large amount of hexanes from which a very small amount of brown precipitate formed. After isolation, the brown residue was dried in vacuo. The entire amount was dissolved in a small amount of CI in an attempt to characterize the product by 31 2 CD P NMR spectroscopy. Unfortunately, no discernible resonance was detected. Broadening of the resonance was expected, due to incomplete coordination (not every P atom is coordinated to a tungsten moiety). In addition, partial decomposition of the product was suspected given the colour of the product (brown) and very low yield. The NMR sample was dried in vacuo and analyzed by triple detection GPC. Despite the short reaction time, addition of excess W(CO) 6 to a solution of polymer 4.2 in diglyme at 160 °C leads to major decomposition of the polymer. The Mof the polymer sample were determined using GPC-LLS and found to decrease from a modest 10 000 g mor 1 to a paltry 600 g mo1 . We suspected that the excess W(CO) 1 6 was causing decomposition of the polymer, so the experiment with smaller amounts of W(CO) 6 were repeated.  In an analogous fashion to the reaction above, thermal reactions were performed of poly(methylenephosphine) 4.2 with 20 and 50 mol % of W(CO) 6 in diglyme at 160 °C for 4 h. The results are summarized in Table 4.2. Decreasing the amount of tungsten in the reaction References start on page 100  Chapter 4  85  decreased the amount of decomposition. With 50 mol % of W(CO) , the polymer started as a 6 yellow solid with a M of 16 000 g moM and after heating became a brown solid with a M of 6000 g mo1 . By adding a mere 20 mol % of W(CO) 1 , the integrity of the polymer appears to 6 remain intact. Not only is the product an orange solid (indicating some chemical change) but the M of the product is similar to that of the starting material (4.2: 21 800 g mo1 ; 4.7a: 18 600 g 1 moM).  Table 4.2 Summary of Conditions for the Thermal Reaction of Poly(methylenephosphine) 4.2 with W(CO) 6 to Form 4.7a.  *  Trial I  Solvent diglyme  Amount of 6 W(CO) xs  Temp. (°C) 160  Time 4h  2  diglyme  50 mol %  160  4h  3  diglyme  20 mol %  160  4h  4  glyme  50 mol %  100  18 h  5  THE  50 mol %  80  6  THE  50 mol %  80  6 days 24 days  M (g moM) I PDI Metallated Polymer polymer 4.2 4.7a 9 600 / 600 / 1.06 3.7 16 000 / 5 700 / 1.1 1.1 21 800 / 18 600 / 1.06 1.3 54 300 / 5 400 / 1.10 2.2 28 000 / 27 000 / 1.14 1.08 54 300 / 57 500 / 1.10 1.16  Yield (%) n/a  Colour brown  %metal lated* n/a  22  brown  n/a  48  green  n/a  n/a  brown  2%  90  orange  5%  97  yellow  6%  Determined by EDX/SEM  P NMR spectroscopy was used to further analyze the tungsten-containing polymer 31 4.7a. The resonance of the product 4.7a in 2 CI is broadened significantly with respect to the CD naked polymer 4.2. The resonance, centered at —10 ppm, has a range of almost 100 ppm (see Figure 4.5). From the model compound studies, I expected a downfield shift for the resonances where P atoms are coordinated to tungsten (see Figure 4.1), and there are some resonances in the expected range (0 to 50 ppm). The incredible broadening is likely due to incomplete complexation: not every P atom is coordinated to a tungsten moiety. The result is that the number of magnetically inequivalent P atoms is greater than in the uncoordinated polymer 4.2. Additionally, given the relatively low molecular weight, decomposition of the polymer likely resulted in further broadening of the resonance. Though coordination is likely to have occurred, References start on page 100  Chapter 4  86  albeit slight, the relative number of P atoms coordinated to W atoms is not determinable from integration in the 31 P NMR spectrum.  (a)  p 11  ,  w”,,’w,1’  (b)  150  Figure 4.4  100  50  0  -50  -100  ppm  CI of: (a) poly(methylenephosphine) 4.2; (b) tungstenCD 31 NMR Spectrum in 2 P containing poly(methylenephosphine) 4. 7a.  With evidence that chemical changes at some P atoms had occurred, i.e. 31 P NMR spectroscopy showed a large broadening of the resonance after the reaction with W(CO) , we 6 needed evidence that W(CC) 5 moieties were coordinated. The IR spectrum of W(CO) 6 exhibits a characteristic band at 1976 cm 1 in THF assigned to the C-C stretch. Functionalized polymer 4.7a showed a very broad stretch centered at 1890 1 cm (see Figure 4.5). This shift of the C-C stretch to lower frequencies is expected since carbonyls are better t-acceptors than phosphines. After substitution of a carbonyl with a phosphine, backbonding to the remaining carbonyls increases, weakening the C-C bonds. This trend is reflected in the IR spectrum of the model compound 4.5a that has a large signal at 1928 cm 1 (assigned to the cis carbonyls). The weaker stretch at 2068 cm 1 is assigned to the trans carbonyls (see Figure 4.5). In the case of tungsten-containing polymer 4.7a, we can conclude, therefore, that there are tungsten moieties with polymeric phosphines as ligands. From the lR spectrum, we could not determine the amount of coordinated phosphines in the polymer 4.7a.  References start on page 100  Chapter 4  87  6 CrCO  4.5c 4.7c  0 U) C))  E  Cl)  6 M0CO  as I— 1.  &5b 4.7b  > G)  6 Wc0 4.5a 4.7a  2200  2100  2000  1900  1800  1700  Wavenumbers (cm-i) Figure 4.5  Infrared Spectra of metal-carbonyl complexes with model compound and polymer in 2 CI solutions (— 10 mg I mL). CH  To further support the presence of W-P bonds in the polymer, a sample of W-containing  4.7a and fts precursor polymer 4.2 were analyzed by XPS (X-ray photoelectron spectroscopy). This surface technique can provide information on both the composition of a sample and the chemical state of the elements within the material. XPS confirmed the presence of W atoms in the sample by the diagnostic peak from the binding energy of a 4f electron centered around 36 eV (see Figure 4.6). Additionally, the binding energy of a P 2p electron (132 eV) was shifted References start on page 100  Chapter 4  88  from that of the uncoordinated polymer 4.2 (130 eV) (see Figure 4.7). Such a shift is indicative of a change in the bonding environment at P. Now, convinced that some of the polymer chain is coordinated to W, we set out to determine the percentage of the P atoms that are coordinated to W. 90000  80000  70000  60000  50000 U, 40000  30000  20000  10000  0  1000  800  600  400  200  0  Binding energy (eV)  Figure 4.6  X-ray photoelectron spectrum of tungsten-containing 4.7a.  References start on page 100  Chapter 4  89 P 2p  [  —  5000  Phi Me — 4 P--C-f-H LMJfl 2  —  W(CO) Ph]  t  Ph Me}-P-C  9H  MesPh x\MesPhjy x+y  =  3500  1  3000 2500 Cl)  1500 1000  500 0 135  133  131  129  127  125  Binding Energy (eV)  Figure 4.7  X-ray photoelectron spectrum of the P 2p binding energy of poly(methylenephosphine) 4.2 and tungsten-containing 4.7a  To determine the percent composition of tungsten in the functionalized polymer 4.7a, one would think that traditional elemental analysis techniques would be appropriate. However, polymer 4.7a did not completely combust, and the results were found to be unreliable. A sample was also analyzed for tungsten content using ICP-MS. The procedure required that the sample dissolve in refluxing aqua regia. However, polymer 4.7a did not dissolve completely causing unreliable results. Also, the molecular weight data from GPC-LLS cannot be used to determine percent metallation in this case as upon coordination, the molecular weight of the polymer decreases.  In order to get an estimate of tungsten content, EDX (Energy Dispersive X-ray) spectroscopy was employed. Unfortunately, EDX spectroscopy cannot detect the presence of atoms smaller than boron and since poly(methylenephosphine)s 4.2 are approximately 7% hydrogen atoms by mass, EDX spectroscopy will only give an approximation. Samples from References start on page 100  Chapter 4  90  trials 4 to 6 (see Table 4.2) were analyzed by EDX. The results suggested that as much as 7% of the backbone was metallated with W fragments. Low temperature (refluxing THF) and long reaction times (> 3 weeks) result in the highest (though still modest) W content.  Coordination of a phosphine to tungsten may cause a weakening in the polymer backbone that results in the ready decomposition of the polymer. Polymer degradation is most likely due to steric repulsion of the large W(CO) 5 moiety (relative to the model compound 4.4) and the very congested polymer 4.2. In fact, in the tungsten-containing model compound 4.5a, there is a slight lengthening in the P(1 )-C(l 1) bond (1 .915(2) A) relative to that of the free phosphine 4.4 (1 .882(1) A). These P-C bonds in the model compounds may be compared to the P-C bond within the polymer backbone. Interestingly, the other P-C bonds shorten slightly upon coordination (P(1)—C(1): 4.4 4.5a  =  =  1.852(1) A vs 4.5a  =  1.848(2) A; P(1)-C(10): 4.4  =  1.840(2) A vs  1.831(2) A). Under high temperatures (>100 °C), the polymer must degrade somewhat,  resulting in low M’s as determined by GPC-LLS.  The analogous substitution reactions with Mo or Cr require lower temperatures than with W. Therefore, metallation with either Mo or Cr may proceed with less polymer degradation. Complete metallation is, however, still unlikely due to the steric congestion about the metals and polymer 4.2. Based solely on the size of the group 6 metals, coordination to Cr is predicted to be less efficient than for Mo.  4.2.3.2 Coordination of Poly(methylenephosphine) 4.2 to Chromium The reaction of homopolymer 4.2 with Cr(CO) 6 was carried out in an analogous fashion . Both reagents were loaded into a flask equipped with a Teflon valve and 6 to that with W(CO) were dissolved in THF. The reaction mixture was degassed by 3 successive freeze-pump-thaw cycles and then heated to 80 °C while being stirred and protected from ambient light. After a period of time, the reaction mixture was cooled to room temperature and added to a relatively References start on page 100  Chapter 4  91  large volume of hexanes in order to precipitate the metallated polymer 4.7c out of solution. Upon isolation, the precipitated solid was heated in vacuo to 40 °C to remove excess Cr(CO) 6 and solvent. The purified product was characterized by 31 P NMR spectroscopy, GPC-LLS, FT IR and EDX.  Just as for the tungsten-containing polymer 4.7a, characterization of chromiumcontaining 47c proved difficult. The 31 P NMR spectrum of 4.7c showed a broadening of the resonance from that of homopolymer 4.2 that was barely discernible from the baseline. FT-IR analysis of the polymer 4.7c showed a shift of the stretching due to the CO groups (broad stretches centered at 1892 and 1858 cm ) relative to Cr(CO) 1 6 (1980 cm ) (see Figure 4.5). 1 Similarly, the chromium-model compound adduct 4.5c shows a strong stretch at 1928 cm 1 with a smaller signal for the trans carbonyls at 2068 cm . Convinced that at least some of the 1 phosphorus atoms in the polymer are coordinated to Cr(CO) 5 fragments, we set out to maximize the metal content.  A number of temperature studies were performed (see Table 4.3 for a summary of the results). Refluxing homopolymer 4.2 and Cr(CO) 6 in THF for 4 hours, resulted in a yellow solid whose IR spectrum showed no indication that coordination had occurred. In fact, evidence of coordination could not be obtained until after at least 6 days of reaction time, at which time GPC-LLS analysis of the orange product revealed a small increase in M from that of homopolymer 4.2. This increase of 1100 g mor 1 corresponds to approximately 6 of the 88 repeat units in the polymer coordinated to Cr(CO) 5 moieties. EDX analysis of the yellow solid was consistent with the modest amount of coordination at 5 % Cr by weight. Lengthening the reaction time to 24 days did not significantly change the degree of metallation. A small increase in reaction temperature (to 100 °C), however, leads to some polymer decomposition; the M decreased from 54 000 to 37 300 g mor . Although modest, thermal metallation of homopolymer 1 4.2 is possible with Cr(CO) 5 moieties. References start on page 100  Chapter 4  92  Table 4.3 Summary of Conditions for the Thermal Reaction of Poly(methylenephosphine) 4.2 with Cr(CO) 6 to Form 4.7c.  Trial  Solvent  Amount of 6 Cr(CO)  Temp. (°C)  Time  1  THF  xs  80  4h  2  THF  xs  80  6 days  3 4 a  THF glyme  xs xs  80 100  24 days 18h  moF ) /PDI M(ci 1 Metallated Polymer polymer 4.2 4.7c 28000/ 28000/ 1.14 1.1 28000/ 29100/ 1.14 1.12 54300/ 56300/ 1.10 1.21 54300/ 37300/ 1.10 1.10  Yield  (%) 99  Colour yellow  94  orange  78  dark yellow orange  n/a  %metall ated 0% 7%a %b 5  %b 4 %b 3  determined GPC-LLS; D determined by EDX  4.2.3.3 Coordination of Poly(methylenephosphine) 4.2 to Molybdenum The reaction of homopolymer 4.2 with Mo(CO) 6 was carried out in an analogous fashion to that of the other group 6 M(CO) 6 complexes. The reagents were loaded into a flask equipped with a Teflon valve and dissolved in glyme (or THF, or diglyme). After having been degassed, the reaction mixture was shielded from ambient light and was heated to 100 °C (or 80 °C in THF, 160 °C in diglyme) while being stirred. After a period of time, the reaction mixture was cooled to room temperature and precipitated from hexanes (see Table 4.4). The molybdenumcontaining polymer 4.7b was heated in vacuo to 40 °C to remove unreacted Mo(CO) 6 and residual solvent. The purified product was mainly characterized by GPC-LLS, FT-lR and EDX.  References start on page 100  Chapter 4  93  Table 4.4 Summary of Conditions for the Thermal Reaction of Poly(methylenephosphine) 6 to Form 4.7b. 4.2 with Mo(CO)  a  Trial 1  Solvent glyme  Amount of 6 Mo(CO) xs  Temp. (°C) 100  Time 7 days  2  THF  xs  80  6 days  3  THF  xs  80  24 days  4  diglyme  20 mol %  160  4h  5  diglyme  100 mol %  160  4h  determined GPC-LLS; b determined by EDX  moF ) /PDI M(p 1 Metallated polymer Polymer 4.2 4.7b 51100/ 54 300/ 1.10 1.46 28 000 / 27 900 / 1.14 1.12 54 300 I 54 400 / 1.10 1.18 21 800 / 25 700 / 1.3 1.14 21 800 / 25 100 / 1.3 1.42  Yield (%) 56  Colour orange  79  salmon  0%  60  brown  >1 %a  97  yellow  23%a  >5  brown  20%a  %metall ated 11%b  Evidence of coordination of homopolymer 4.2 to molybdenum was confirmed through FTIR. Akin to the observations for metallated 4.7a and 4.7c, the stretching frequency for the cis carbonyls was assigned to the broad absorbance centered at 1920 cm 1 in 2 CI In a CH CH . CI 2 solution, Mo(CO) 6 has an intense carbonyl signal at 1980 cm , whereas the coordination 1 compound 4b shows a large signal at 1940 cm 1 (assigned to the cis carbonyls) with a smaller signal for the trans carbonyls at 2070 cm* Again, from the IR data, the degree of metallation was difficult to discern.  The degree of metallation for 4.7b, mainly determined using GPC-LLS and EDX analyses, depended strongly on the reaction conditions. Metallation of around 10% was achieved by heating the homopolymer 4.2 and Mo(CO) 5 in glyme to 100 °C, akin to the preparation of model compound 4b. This relatively high metal content, though exciting, was accompanied by a relatively low yield and an overall decrease in M most likely due to decomposition. These metallated polymers appear to be relatively sensitive to heat. Therefore, the reaction was repeated in THF at a slightly cooler 80°C. Although the M’s of the resulting polymers were not less than the M’s of the starting materials, they were also not much larger. Despite a long reaction time, there appeared to be very little coordination of Mo. In fact, 31 P  References start on page 100  Chapter 4  94  NMR analysis revealed no change in the resonance of homopolymer 4.2 (ó that of the isolate product (ö  =  =  -7, broad) to  -7, broad). Metallation of only 10% was too modest. So, despite  the polymers instabilities to high temperatures, I heated polymer 4.2 in the presence of 20 mol % of Mo(CO) 6 to 160 °C for a short time. From analysis by GPC-LLS, the resulting metallated polymer 4.7b, had an M 4 000 g mo1 1 greater than the homopolymer which corresponds to -20% metallation. Increasing the relative amount of Mo(CO) 6 under similar conditions does not significantly affect the percent metallation, but can affect the yield greatly. Additionally, the PDI of the resulting polymer is broadened relative to that the starting material indicating a certain amount of decomposition.  4.3 Conclusion  Finally, we have shown that poly(methylenephosphine) 4.2 can be partially metallated with Group 6 metal carbonyls through the thermally induced substitution of a CO group. Model compounds for the metallated polymers, phosphine-metal complexes 4.5a, 4.5b and 4.5c were successfully prepared and characterized. The objective was to achieve high metal loading of the polymer 4.2 with the hopes of preparing useful metal-containing materials or ceramic precursors. We now are certain that phosphorus-metal bonds can be formed. However, for total metallation of polymer 4.2, a less sterically hindered, larger metal center should be selected.  4.4 Experimental Section  4.4.1  General Methods and Instrumentation Al! manipulations of air- and/or water-sensitive compounds were performed under a  nitrogen atmosphere using standard Schlenk or glovebox techniques. Hexanes and dichloromethane were deoxygenated by sparging with nitrogen and dried by passing through a column containing activated alumina. THF, glyme and diglyme were freshly distilled from References start on page 100  Chapter 4  95  sodium/benzophenone ketyl. CDCI 3 was distilled from P . Bottled 2 5 0 2 CI was purchased CD from Cambridge Isotope Laboratories and used as received. MesP=CPh 2 compound  44,17  and poly(methylenephosphine)  4.223  4.122  and model  were prepared following literature  procedures. The metal carbonyls were purified by sublimation before use.  P, 13 31 C and 1 H NMR spectra were recorded on BrukerAV300 MHz and AV400 MHz spectrometers. Chemical shifts for 31 P NMR spectra are reported relative to 4 P0 as an 3 H external standard (85% in H 0, ó 2 relative to 2 CI (ô CD residual CHDCI 2 (ô  =  =  =  0 ppm). Chemical shifts for 13 C NMR spectra are reported  54.0 ppm). Chemical shifts for 1 H NMR spectra are reported relative to  5.32 ppm). Mass spectra were recorded on a Kratos MS 50 instrument.  Elemental analysis was performed by Mr. Minaz Lakha in the Departmental Microanalysis Facility.  Molecular weights were estimated by triple detection gel permeation chromatography (GPC-LLS) using a Waters liquid chromatograph equipped with a Waters 515 HPLC pump, Waters 717 plus autosampler, Waters Styragel columns (4.6 x 300 mm) HR5E (2000-4 000 000), HR4 (5000-500 000), and HR2 (500-20 000), Waters 2410 differential refractometer 940 nm, 40 °C), Wyatt tristar miniDAWN (laser light scattering detector operating at  =  (=  690 nm),  and a Wyatt ViscoStar viscometer. A flow rate of 0.5 mL min 1 was used, and samples were dissolved in THF (ca. 2 mg mL ). 1  All IR samples were prepared as solutions in 2 CI and their spectra were recorded on CH , a Thermo Nicolet 4700 FT-IR spectrometer by the author. All XPS spectra were recorded by Ken Chung Wong at the Advanced Materials and Process Engineering Laboratory at the University of British Columbia with a Leybold MAX 200 X-ray Photoelectron Spectrometer (XPS/ESCA) with a Dual anode (Mg Ka and Al Ka) achromatic X-ray source. EDX experiments  References start on page 100  Chapter 4  96  were performed by the author at UBC with a Hitachi S-3000N SEM with light element EDX. No conductive coating was used for imaging and analysis of samples.  4.4.2  General procedure for phosphine complexes. This preparation is a modification of the literature procedure according to Magee et a!. 13  A bomb was charged with model compound 3 and excess M(CC) 6 and an ethereal solvent. The solution was degassed by 3 successive freeze-pump-thaw cycles and heated to reflux with a strict exclusion of ambient light. The reaction was monitored by 31 P NMR spectroscopy. The solvent was removed in vacuo. Excess M(CC) 6 was removed by sublimation from the resulting yellow residue. The compound was purified by recrystallization.  4.4.3  Preparation of 5 )(Me)MesPW(CO) (4.5a) 2 (HCPh The reaction flask was charged with W(CC) 6 (393 mg, 1.10 mmol), model compound 3  (250 mg, 0.75 mmol) and diglyme (11 mL). Total reaction time was 4 hrs. The product was purified by recrystallization from ethanol giving light sensitive, slightly yellow crystals. Yield= 106mg (20 %).  P NMR 2 31 CI 121.5 MHz): ó 7.9 (s, 1 (CD , Jpw=236.3Hz); 1 H NMR 2 CI 300 MHz): ó (CD , 7.44-6.89 (m, 12H, aromatic), 5.22 (d, 1H, CH,  JHp= 2  7.48 Hz), 2.80 (brs, 3H, o-Mes-CH ), 2.40 3  (br s, 3H, o-Mes-CH ), 2.29 (s, 3H, p-Mes-CH 3 ), 2.14 (d, 3H, P-CH 3 , 3 CI 75 MHz): ó (CD , 2 Jcp = 2  =  6.4 Hz), 142.4-140.8  ), 25.1 (d, P-CH 3 CH , 3 Calcd.  202.2 (d, trans-CC,  for  Jcp 1  (m,  Jcp = 2  (s,  JHP = 2  5.24 Hz); 13 C NMR  22.1 Hz), 199.8 (d, cis-CC, 1 Jcw = 127.1 Hz,  Mes-C), 134.1- 129.0  23.9 Hz), 22.7  =  (m,  Ph-C), 55.9  (s,  P-CH), 27.1  o-Mes-C). MS (El, 70eV): m/z  =  (s, p-Mes  656. Anal.  C 2 H P 5 0 W: 8 C, 51.20; H, 3.84. Found: C, 51.40; H, 4.20. lR 2 5 CI (CH  solution):  2068 cm 1 (trans-CC), 1928 cm 1 (cis-CO).  References start on page 100  Chapter 4 4.4.4  97  )(Me)MesPMo(CO) (4.5b). 2 (HCPh Preparation of 5 The reaction flask was charged with Mo(CO) 6 (260 mg, 1.0 mmol), model compound 3  (250 mg, 0.75 mmol) and glyme (10 mL). Total reaction time was 20 hrs. The product was purified by recrystallization from ethanol giving light sensitive, slightly colourless crystals. Yieldt 301 mg (71 %).  CI 121.5 MHz): 828.5(s); 1 (CD , P NMR 2 31 H 2 CI 300 MHz): 8 6 (CD , aromatic), 5.06 (d,  JHp= 2  7.31-6.56 (m, 12H,  6.9 Hz, 1H, CHPh ), 2.66 (brs, 3H, o-Mes-CH 2 ), 2.15 (brs, 3H, o-Mes 3  ), 1.72 (d, 3 ), 1.94 (s, 3H, p-Mes-CH 3 CH =  =  202.2 (d, trans-CC, 2 Jcp  =  JHP = 2  4.2 Hz, 3H, 13 ); NMR 2 3 P-CH C CI 75 MHz): 8 (CD ,  22.1 Hz), 199.8 (d, cis-CO, 2 Jcp  134.2- 129.1 (m, Ph-C), 54.7 (s, P-CH), 27.1 22.5 (s, o-Mes-C). MS (El, 70 eV): m/z  =  (5,  =  6.2 Hz), 141.8-140.2 (m, Mes-C),  ), 24.3 (d, P-CH 3 p-Mes-CH , 3  Jcp= 1  24.0 Hz),  570. Anal. Calcd. for O C 2 H P 5 Mo: 8 C, 59.16; H, 4.43. 5  Found: C, 60.10; H, 4.12. IR 2 CI solution): 2070 cm (CH 1 (trans-CC), 1940 cm 1 (cis-CO).  4.4.5  )(Me)MesPCr(CO) (4.5c) 2 (HCPh Preparation of 5 The reaction flask was charged with Cr(CO) 6 (230 mg, 1.0 mmol), model compound 3  (252 mg, 0.75 mmol) and THF (5 mL). Total reaction time was 20 hrs. The product was a yellow solid. Yield= 150 mg (38 %).  P NMR 2 31 CI 121.5 MHz): 839.2(s); 1 (CD , H 2 CI 300 MHz): 8 6 (CD , aromatic), 5.09 (d,  JHP = 2  7.51-6.47 (m, 12H,  6.7 Hz, 1 H, CHPh ), 2.69 (br s, 3H, o-Mes-CH 2 ), 2.18 (br s, 3H, o-Mes 3  ), 2.03 (s, 3H, p-Mes-CH 3 CH ), 1.88 (d, 3 =  =  203.2 (d, trans-CC, 2 Jcp  =  JHP = 2  4.2 Hz, 3H, 13 ); NMR 2 3 P-CH C CI 75 MHz): 8 (CD ,  22.3 Hz), 200.0 (d, cis-CO, 2 Jcp  =  5.9 Hz), 142.6-140.4 (m, Mes-C),  134.3- 129.2 (m, Ph-C), 53.7 (s, P-CH), 27.2 (s, p-Mes-CH ), 26.2 (d, P-CH 3 , 3 22.6 (s, o-Mes-C). MS (El, 70 eV): m/z  =  Jcp= 1  22.7 Hz),  524.  References start on page 100  Chapter 4  4.4.6  98  Metallation of poly(methylenephosphine) 4.2 with M(CO) 6 The experimental procedures for 4.7a, 4.7b, and 4.7c are given below as an example:  To a Kontes bomb was added poly(methylenephosphine) 4.2 (105 mg, M =  =  , PDI 1 21 800 g mor  1.06) and W(CO) 6 (20 mg) and diglyme (2 mL). The reaction mixture was degassed through  three cycles of freeze-pump-thaw and then heated to 160 °C in the dark. After heating for 4 hours, the reaction mixture was poured into a Schienk tube containing 50 mL of hexanes. The metallated polymer precipitated immediately from solution and was isolated by filtration. The resulting brown powder was dried in vacuo for at least 24 h. Yield  =  50 mg (48 %).  See Tables 4.2, 4.3 and 4.4 for the results of all trials.  4.4.7  X-ray Crystallography Crystal data and refinement parameters are listed in Table 4.4. All single crystals were  immersed in oil and mounted on a glass fiber. Data for 4.5a were collected on a Bruker X8 APEX diffractometer with graphite-monochromated Mo Ka radiation by Dr.Brian 0. Patrick. Data for 4.5b were collected on a Bruker X8 APEX II diffractometer by Joshua Bates. Data were collected and integrated using the Bruker SAINT software package. 24 All structures were solved by direct methods and subsequent Fourier difference techniques and were refined anisotropically for all non-hydrogen atoms. Hydrogen atoms were included in idealized positions and refined isotropically. All data sets were corrected for Lorentz and polarization effects. All calculations were performed using the SHELXTL crystallographic software package from Bruker-AXS  25  References start on page 100  Chapter 4  99  Table 4.5 Details of Crystal Structure Determinations of 4.5a and 4.5b 4.5a 4.5b formula formula weight (g moF ) 1 crystal system space group colour a (A) b (A) c(A) a(deg) f3 (deg) y(deg)  ) 3 V(A Z T(K) i(Mo Ku) (cm ) 1 crystal size (mm) ) 3 dcaIcd (g cm 20(max) (deg) no. of rflns no. of uniquedata R(int) rfln/param ratio Ri [I > 2.OOa(l) wR2 (all data) GOF a 1 = I Fc R FcI 1/ZI F 1; 0 -  C 2 H P 5 0 W 8 5 C 2 H P 5 MoO 8 5 656.30 568.39 monoclinic monoclinic P2 /c 1 P2 1c 1 colourless colourless 10.5368(4) 10.535(5) 22.3632(9) 22.334(5) 11.4187(5) 11.423(5) 90 90 107.044(2) 107.105(5) 90 90 2572.5(2) 2568.8(1 8) 4 4 173(1) 173(2) 45.89 0.609 0.35 x 0.25 x 0.12 0.1 x 0.1 x 0.1 1.695 1.470 55.8 63.04 44780 43676 6124 8388 0.028 0.0564 19.14 20.16 0.016 0.0364 0.038 0.0826 1.07 1.036 b 2 = [Z(F wR 2 F) 0 ”. 1 ] ) 2 0 IZw( F 2 —  References start on page 100  Chapter 4 4.5  100  References  1. A. S. Abd-EI-Aziz. Coord. Chem. Rev. 2002, 233-234, 177. 2. A. S. Abd-EI-Aziz. Macromol. Rapid Commun. 2002, 23, 995. 3. V. Chandrasekhar, Inorganic and Organometallic Polymers. 1st ed.; Springer: New York, 2005. 4. I. Manners. J. Polym. Sd. Part A: Polym. Chem. 2002, 40, 179. 5. I. Manners, Synthetic Metal-Containing Polymers. WiIey-VCH: Weinheim, 2004. 6. K. J. T. Noonan, D. P. Gates. Annu. Rep. Prog. Chem., Sect. A: lnorg. Chem. 2007, 103, 407. 7. I. Manners. Angew. Chem. Int. Ed. EngI. 1996, 35, 1603. 8. J. E. Mark, H. R. Alicock, R. West, Inorganic Polymers. 2nd ed.; Oxford University Press: Toronto, 2005. 9. N. E. Leadbeater, M. Marco. Chem. Rev. 2002, 102, 3217. 10. M. J. Farrall, J. M. J. Fréchet. J. Org. Chem. 1976, 41, 3877. 11. B. M. Trost, E. Keinan. J. Am. Chem. Soc. 1978, 100, 7779. 12. C.-W. Tsang, B. Baharloo, D. Riendl, M. Yam, D. P. Gates. Angew. Chem.  mt.  Ed. 2004,  43, 5682. 13. C. N. Matthews, T. A. Magee, J. H. Wotiz. J. Am. Chem. Soc. 1959, 81, 2273. 14. T. A. Magee, C. N. Matthews, T. S. Wang, J. H. Wotiz. J. Am. Chem. Soc. 1961, 83, 3200. 15. T. A. van der Knaap, F. Bickeihaupt. Tetrahedron Lett. 1982, 23, 2037. 16. C.-W. Tsang, M. Yam, D. P. Gates. J. Am. Chem. Soc. 2003, 125, 1480. 17. B. H. Gillon, K. J. T. Noonan, B. Feldscher, J. M. Wissenz, Z. M. Kam, T. Hsieh, J. J. Kingsley, J. I. Bates, D. P. Gates. Can. J. Chem. 2007, 85, 1045. 18. S. T. Oyama. Journal of Catalysis 2003, 216, 343. 19. S. Rundqvist. Nature 1966, 211, 847. 20. W. Strohmeier, H. Hellmann. Ber. Bunsen Ges. 1964, 5,481. References start on page 100  Chapter4  101  21. G. Schwenzer, M. Y. Darensbourg, D. J. Darensbourg. Inorg. Chem. 1972, 11, 1967. 22. M. Yam, J. H. Chong, C.-W. Tsang, B. 0. Patrick, A. E. Lam, D. P. Gates. Inorg. Chem. 2006, 45, 5225. 23. K. J. T. Noonan, D. P. Gates. Angew. Chem.  mt.  Ed. 2006, 45, 7271.  24. Computer program: SAINT V. 7.03A ed. BrukerAXS Inc., Madison, WI. (1997-2003). 25. Computer program: SHELXTLV. 5.1 ed. BrukerAXS Inc., Madison, WI. (1997).  References start on page 100  102  Chapter 5  Macromolecular Corn plexation of PoIy(methylenephosphine) to Gold(l): A Facile Route to Highly Metallated Polymers*  5.1 Introduction  Poly(methylenephosphine)s (PMP), are an unprecedented class of macromolecules which possess alternating phosphorus and carbon atoms (see Scheme 5.1).1 In particular, the (5.1) can be polymerized under ambient temperatures through the 2 phosphaalkene MesP=CPh addition of substoichiometric amounts of n-BuLi to form PMP 5.2 (Scheme 5.2).2 An appealing feature of PMP’s is their potential functionalization through the phosphine moieties. I am particularly interested in exploiting PMP’s as precursors to well-defined metal-containing macromolecules PMP-M (Scheme 5.1). Previously, our group had shown that PMP-containing copolymers are effective supports in Pd-catalyzed Suzuki cross-coupling. 3 However, welldefined Pd-complexes have not been isolated. Chapter 4 outlined the difficulties in preparing and characterizing metal coordination to classical organometallic complexes. I wanted to select a valuable metal for which phosphines are good ligands.  Initiator  \  / PA  *  i  H J PMP Scheme 5.1  j M r .  [In PMPM  A version of this chapter has been published. Bronwyn H. Gillon, Brian 0. Patrick and Derek P. Gates, “Macromolecular Complexation of PoIy(methylenephosphine) to Gold(l): A Facile Route to Highly Metallated Polymers,” Chem. Commun., 2008, 2161-2163. Copyright 2008 Royal Society of Chemistry.  103  Chapter 5  /  PzC  Ph  E 1.n-BuLi  n-Bu  Ph 2. MeOH -LiOMe  Me  Phi P—C  I  Mes Ph  5.1  H  I  ,  5.2  Scheme 5.2  When choosing target metals for coordination studies, gold(l) has attracted our attention. Gold(l) has a high affinity for phosphine ligands and exhibits a tendency to form linear P-Au-X complexes which would permit high Au loadings in the densely substituted PMP-M. Moreover, gold-containing polymers are attracting considerable interest due to their exciting potential applications in nanochemistry, catalysis, and chemosensors. Much of this work has been in the area of solid state gold coordination polymers that, with the exception of gold(l) polyynes, tend to lose their polymeric structure in solution. ° Gold(l) containing polymers with covalent 4 backbones are less common. ’ 11  12  Herein, the preparation of soluble gold-containing  macromolecules with high gold loadings through the macromolecular complexation of PMP to Au(l) is reported. First, the potential for PMP 5.2 to act as a ligand for transition metals was evaluated by studying the reactivity of the molecular model 5.3 with Au(l).  5.2 Results and Discussion  5.2.1  Coordination of Au(I) to model compound 5.3 Model compound 5.3, which was prepared from 5.1  13  was treated with (tht)AuCl (tht  =  tetrahydrothiophene) in 2 CI solution. Monitoring the reaction progress by 31 CH P NMR spectroscopy showed that the signal for 5.3 at —23.0 ppm disappeared and was replaced by a new signal at 16.0 ppm assigned to the coordination compound 5.4 (see Figure 5.1 (a) and (b)). Slow diffusion of EtCH into a concentrated 2 CI solution of the product afforded 5.4 which CH was characterized by elemental analysis, El MS (Mt, mlz  =  564) and X-ray crystallography. The  References start on page 113  Chapter 5  104  H and 13 1 D solution are consistent with the formulated 6 C NMR spectra of the crystals in C structure of 5.4.  Ph  /  CI Au  Ph 1. MeLI  P=C “ Mes Ph 2. MeOH LIOMe  I  ..  Me—P—C—H  Mes Ph  -  5.1  f  (tht)AuCI  CHCI, RT tht  -  Me—P—C—H  Mes Ph 5.4  5.3  (a)  (b)  (C)  r  -  (d)  200  150  100  50  0  -50  -100 ppm  Figure 5.1 P NMR 2 31 CI 300 K) spectra of (a) model compound 5.3, (b) gold complex (CD , 5.4, (c) polymer 5.2 and (d) coordinated polymer 5.5 (* tentatively assigned to phosphine oxide moieties (of oxidized polymer &lp = 471)  References start on page 113  Chapter 5  105  The solid-state molecular structure of 5.4 (Figure 5.2) displays similar metrical parameters to model compound  5•313  The molecular structure shows that, despite coordination  to gold, the solid-state structure of 5.4 does not significantly differ from model compound 5.3. For example, the length of the P-C bonds in 5.3 average 1.858(2) A and after coordination average 1.853(7) A. One interesting feature of 5.4 is that electron-group geometry about the P atom is close to tetrahedral as evidenced by a widening of the C-P-C bond angles with respect to 5.3 [5.4: avg.  =  107.0(3)° vs. 5.3: avg.  2.257(1) A; Au(1)-Cl(1)  =  =  102.7(1)°]. The P-Au and Au-Cl bonds [P(1)-Au(1)  2.305(1) A) are in the long end of the range observed for similar  gold(l)-phosphine complexes [Au-Cl: 2.21  —  2.26 A; Au-Cl: 2.23  —  2.31 A]. 147 Interestingly, the  P-Au-Cl bond angle deviates slightly from linearity [P(1)-Au(1)-Cl(1)  =  175.69(4)°] with the Cl  bending towards the less hindered P-Me moiety. The closest AuAu contact of 9.47 A in 5.4 is much longer than expected if aurophilic interactions were present (ca. 3 A). 18 These observations are not surprising since bulky gold(I) phosphines show bent Cl-Au-P angles [e.g. PAuCI: Cl-Au-P 3 (m-tolyl)  =  175.1(1)°J and often do not show aurophilic interactions. 19  References start on page 113  Chapter 5  106 cli  07  021  Aul  020 019  022 02  03  P1  01  023  018  013  014  C4 012 do 08  017  06  016  05 09  Figure 5.2 The solid-state molecular structure of 5.4 (50% probability ellipsoids). Hydrogen atoms are omitted for clarity. Selected bond lengths (A): P(1)-C(1) = 1.852(4); P(1)-C(10) = 1.833(4); P(1)-C(11) 1.875(4); P(1)-Au(1) = 2.257(1); Au(1)-Cl(1) = 2.305(1). Selected bond angles (°): C(1)-P(1)-C(10) = 109.0(2); C(1)-P(1)-C(11) = 105.7(2); C(10)-P(1)-C(11) = 106.3(2); C(1 )—P(1 )—Au(1) = 11 5.2(1): C(1 0)—P(1 )—Au(1) = 107.1(1); C(1 I )—P(1 )—Au(1) = 113.2(1); P(1 )— Au(1)-Cl(1) = 175.69(4).  5.2.2  Coordination of Gold(l) to poly(methylenephosphine) to yield gold-containing  polymer 5.5 With model complex 5.4 in hand, our next objective was to study the metallation of the polymer. The anionic polymerization of 5.1 in glyme using n-BuLi as the initiator afforded PMP 5.2 (M  =  38 900 g mor , PDI 1  =  1 •34)•2 In an attempt to prepare complexed polymer 5.5, the  phosphine polymer 5.2 was treated with (tht)AuCl (1 equiv per P) at room temperature in 2 CI CH solution. After 1 h, an aliquot was removed from the reaction mixture and analyzed by 31 P NMR spectroscopy (Figure 5.1 (c) and (d)). Remarkably, the broad resonance for the uncomplexed polymer 5.2 (ó  =  —7) had entirely disappeared and was replaced by a new broad resonance  assigned to 5.5 (ó  =  25). For comparison, a similar downfield shift is observed for the model  compound (5.3 vs. 5.4: Áö  =  39; 5.2 vs. 5.5: Aó  =  32). The gold-containing polymer 5.5 was  References start on page 113  Chapter 5  107  purified by precipitation of a concentrated 2 CI solution into hexanes. The resulting white CH powder was further characterized by 1 H and 13 C NMR spectroscopy.  CI PhI  I  I I I n-Bu-I--P—C—f-H I I I I[Mes •.  PhJn  (tht)AuCI CI RT CH , 2 -tht  5.2  rAu•‘.  Phi  I I I • n-Buf-P—C--l--H [Mes Phin 5.5  Scheme 5.3  The novel gold-containing polymer 5.5 was also characterized by triple detection GPC in THF solution. Importantly, the absolute number average molecular weight for 5.5 (M moM) increased substantially upon coordination to gold (cf. 5.2: M  =  =  71 600 g  38 900 g moM). The  molecular weight of 5.5 is the highest yet observed for a PMP-based polymer and is consistent with a high degree of P-metallation. The polydispersity indices for 5.2 and 5.5 are both narrow (5.2: PDI  =  1.34; 5.5: PDI  =  1.29) which suggests that the integrity of the backbone is retained  upon coordination. Thermogravimetric analysis of 5.5 (Figure 5.3) revealed an onset temperature of polymer degradation (Tonset uncomplexed 5.2 (Tonset  265  oc)l  =  325 °C) which is considerably higher than that for  Remarkably, after heating to 1000 °C a shiny, lustrous  residue was obtained. The residue was 40% of the initial mass of 5.5 which is consistent with the expected gold content (36%). This residue is speculated to be composed primarily of elemental gold. Further studies are underway to confirm this hypothesis and to investigate the potential use of these polymers as polymer-supported catalysts or precursors to well-defined gold nanostructures.  References start on page 113  Chapter 5  108  100.0 90.0 80.0 70.0 60.0 C.)  0.  50.0 40.0 30.0 20.0 10.0 0.0 0  100  200  300  400  500  600  700  800  900  1000  Temperature (“C)  Figure 5.3 TGA trace for gold-containing polymer 5.5. Collected under a nitrogen atmosphere at a heating rate of 10 °Clmin.  5.3  Conclusion  A novel gold-phosphine complex 5.4 was prepared as a model for the more difficult polymer system. For the first time, poly(methylene)phosphine 5.5 was successfully and largely metallated with gold(l) moieties. This achievement paves the way for the possibility of preparing gold-containing materials or macrostructures, micelles for example, as well as using the materials for gold(I) catalytic transformations.  References start on page 113  Chapter 5  109  5.4 Experimental  5.4.1  Materials and General Procedures All manipulations of oxygen- and/or water-sensitive compounds were performed under a  nitrogen atmosphere using standard Schlenk and/or glovebox techniques. Hexanes, toluene and dichloromethane were deoxygenated with nitrogen and dried by passing through a column containing activated alumina. EtCH was dried by distilliing over CaH 2 and deoxygenated with nitrogen. 2 CI C CD , D and CDCI 6 3 were purchased from Cambridge Isotope Laboratories and used as received. MesP=CPh ° Mes(Me)PCPh , 2 H 2  5•3,13  polymer 5.2,2 and (tht)AuCI 21 were  prepared following literature procedures.  P, 1 31 H and 13 H} NMR spectra were recorded on BrukerAV300 orAV400 1 C{ spectrometers at room temperature. Chemical shifts for 31 P NMR spectra are reported relative P0 as an external standard (85% in H 3 H to 4 0, o 2 are reported relative to CDCI 3 (8 relative to residual CHCI 3 (8  =  =  =  0). Chemical shifts for 13 H} NMR spectra 1 C{  77.2). Chemical shifts for 1 H NMR spectra are reported  7.27) or 5 HD (8 6 C  =  7.16). Mass spectra were recorded on a  Kratos MS 50 instrument. Elemental analyses were performed by Mr. Minaz Lakha in the Departmental Microanalysis Facility.  5.42  Synthesis of [Mes(Me)(CPh H)P•AuCI] (5.4) 2 To a stirred solution of (tht)AuCI (20 mg, 0.06 mmol) dissolved in 2 CI (1 mL) was CH  added model compound  5•313  (21 mg, 0.06 mmol) in 2 CI (4 mL). The reaction was CH  monitored by 31 P NMR spectroscopy (8  =  16.0) and after 1 h the solvent was removed in vacuo  leaving a white residue. The product was extracted with toluene (3 x 2 mL), and the solvent removed in vacuo to afford 5.4 as a colourless solid (33 mg, 94 %). X-ray quality crystals were obtained from slow diffusion of EtCH into a concentrated solution of 5.4 in 2 CI CH . References start on page 113  Chapter5  110  P NMR 2 31 CI 162 MHz): 8 (ppm): (CD ,  7.65 (d,  JHH=  16.0 (s). 1 H NMR (C , 400.13 MHz): 8 (ppm): D 6  8 Hz, 2H, Ph-I-i), 7.17 (m, 2H, Ph-H), 7.04 (m, 3H, Ph-H), 6.84 (m, 3H, Ph-H),  6.45 (brs, 2H, m-Mes-H), 4.52 (d,  JPH= 2  (s, 3H, p-CH -Mes), 1.15 (d, 3  9 Hz, 3H, 3 P-Cl-I ) . 13 C NMR (CDCI , 75.5 MHz) (assignments 3  JPH= 2  16Hz, 1H, P-CPh H), 2.23 (s, 6H, o-CH 2 -Mes), 1.89 3  made with the aid of HMQC experiments) ô(ppm): 143.3 (d, 1 Jcp= 10Hz, i-Mes-C), 142.1 (brs, Mes-C), 137.7 (s, Mes-C), 136.7 (s, Mes-C), 132.1 (d, J 9 Hz, Ph-C), 130.1-1 27.8 (m, Ph-C), 52.8 (d, Jcp 1  =  Jcp= 1  32 Hz, P-CH), 25.7 (d,  Jcp= 3  9Hz, 3 o-Mes-CH ) , 21.2 (s, p-Mes-CH ), 16.8 (d, 3  35 Hz, 3 P-CH ) . MS (El, 70eV): mlz (%)  =  564 (0.4) [Mt], 332 (50) [M-AuCl], 167 (100)  [CHPh ] 2 , 165 (50) [PMeMes], 119 (15) [Mes]. Anal. Caic. for H PAuCI: C 2 2 C, 48.91; H, 4.46. 1 Found: C, 50.38; H, 4.75.  5.4.3  Synthesis of n-Bu(MesP(AuCI)CP h )H (5.5) 2 To a stirred solution of (tht)AuCI (45 mg, 0.14 mmol) in 2 CI (5 mL) was added CH  polymer 5.22 (45 mg, M  38 900  800 g mor , PDI 1  =  1.34  reaction was monitored by 31 P NMR spectroscopy (8  =  24) and after 1.5 h the solvent was  removed  =  ±  ±  0.03) in 2 CI (5 mL). The CH  in vacuo leaving a yellow solid. The polymer was precipitated from a solution of  CI (1 mL) into cold hexanes (15 mL). After filtration, the solvent was removed in vacuo CH 2 affording 5.5 as a pale yellow solid (58 mg, 74 %).  P NMR 2 31 CI 162.0 MHz): 8 (ppm): 24 (br). 1 (CD , H NMR (CDCI , 300 MHz): 8 (ppm): 9.0 3 -  6.5 (Ar-I-I), 2.4  —  1.7 (Me-H). 13 C NMR (CDCI , 75.5 MHz): 8 (ppm): 146.5 (br, Mes-C), 142.2 3  (br, Mes-C), 138.0 (br, Mes-C), 132-1 24 (br mult, Ph-C), 52.1 (br, P-C-P), 23.1 (br, o-CH ), 28.2 3 (br, p-CH ). GPC-LLS (g/mol): M 3  =  71 600  ±  600 g moM, PDI  =  1.29  ±  0.01), dn/dc  =  0.16 (as  determined by 100% mass recovery methods). Satisfactory elemental analyses could not be obtained presumably due to ceramic formation. TGA (N 2 atmosphere): 5 % weight loss 25 —  References start on page 113  Chapter 5 270 °C, 45 % weight loss 270  111  -  450 °C, 15 % weight loss 450  -  770 °C, plateau 770— 1000 °C  with 40 % residue remaining.  5.4.4  X-ray Crystallography Crystal data and refinement parameters are listed in Table 5.1. The single crystal was  immersed in oil and mounted on a glass fiber. Data for 5.4 were collected on a Bruker X8 APEX diffractometer with graphite-monochromated Mo Ka radiation. Data was collected and integrated using the Bruker SAINT software package. 22 The structure was solved by direct methods and subsequent Fourier difference techniques and was refined anisotropically for all non-hydrogen atoms. Hydrogen atoms were included in idealized positions and refined isotropically. The data sets were corrected for Lorentz and polarization effects. All calculations were performed using the SHELXTL crystallographic software package from Bruker-AXS. 23 Depository numbers for the .cif file deposited with the Cambridge Crystallographic Database: CCDC 665759.  References start on page 113  Chapter 5  Table 5.1  112 Details of Crystal Structure Determinations of 5.4 5.4 formula C 2 H C PAuCI•1/2CH 2 3 5 I fw (g moF ) 1 607.28 cryst syst monoclinic space group 02/c (#1 5) colour colourless a(A) 17.031(1) b (A) 7.7689(5) c(A) 35.310(3) a(deg) 90 93.431(4) (deg) fi y(de9) 90 V(A) 4663.5(6) Z 8 T(K) 173(2) i(Mo Ku) (cm 66.13 ) 1 cryst size (mm) 0.35 x 0.35 x 0.10 ) 3 1.730 dcalcd (g cm 20(max) (deg) 55.7 no. of rflns 30781 no. of unique data 5534 0.0524 rfln/param ratio 21.9 ; wR 1 R 2 [I > 2.000(l)]a 0.0304; 0.0696 ; wR 1 R 2 (all data)a 0.0369; 0.0722 GOF 1.062 a )L/w(Fo F ] ) . 2 h/ 1 = IF IF /F R 2 wR = 2 0 [(F I; 0 —  -  References start on page 113  Chapter5 5.5  113  References  1. C.-W. Tsang, M. Yam, D. P. Gates. J. Am. Chem. Soc. 2003, 125, 1480. 2. K. J. T. Noonan, D. P. Gates. Angew. Chem. tnt. Ed. 2006, 45, 7271. 3. C. W. Tsang, B. Baharloo, D. Riendi, M. Yam, D. P. Gates. Anyew. Chem.  mt.  Ed. 2004, 43,  5682. 4. R. J. Puddephatt. Coord. Chem. Rev. 2001, 216-217, 313. 5. M. J. Katz, H. Kaluarachchi, R. J. Batchelor, A. A. Bokov, Z.-G. Ye, D. B. Leznoff. Angew. Chem.  mt.  Ed. 2007, 46, 8804.  6. C. A. Wheaton, R. J. Puddephatt. Angew. Chem.  mt.  Ed. 2007, 46, 4461.  7. E. C. Constable, C. E. Housecroft, M. Neuburger, S. Schaffner, E. J. Shardlow. Dalton Trans. 2007, 2631. 8. C. A. Wheaton, M. C. Jennings, R. J. Puddephatt. J. Am. Chem. Soc. 2006, 128, 15370. 9. U. Siemeling, D. Rother, C. Bruhn, H. Fink, T. Weidner, F. Trager, A. Rothenberger, D. Fenske, A. Priebe, J. Maurer, R. Winter. J. Am. Chem. Soc. 2005, 127, 1102. 10. V. J. Catalano, M. A. Malwitz, A. 0. Etogo. lnorg. Chem. 2004, 43, 5714. 11. M. Sebastian, M. Hissler, C. Fave, J. Rault-Berthelot, C. Odin, R. Reau. Angew. Chem.  mt.  Ed. 2006, 45, 6152. 12. C. Diaz, M. L. Valenzuela, G. G. A. Carriedo, F. J. Garcia-Alonso, A. Presa. Polym. Bull. 2006, 57, 913. 13. B. H. Gillon, K. J. T. Noonan, B. Feldscher, J. M. Wissenz, Z. M. Kam, T. Hsieh, J. J. Kingsley, J. I. Bates, D. P. Gates. Can. J. Chem. 2007, 85, 1045. 14. R. C. Bott, P. C. Healy, G. Smith. Polyhedron 2007, 26, 2803. 15. E. C. Alyea, G. Ferguson, S. Kannan. Polyhedron 2000, 19, 2211. 16. R. C. Bott, C. A. Bowmaker, R. W. Buckley, P. C. Healy, M. C. S. Perera. Aust. J. Chem. 2000, 53, 175.  References start on page 113  Chapter5  114  17. E. C. Alyea, G. Ferguson, J. F. Gallagher, J. Malito. Acta Crystallogr., Sect. C: Ciyst. Struct. Commun. 1993, 49, 1473. 18. H. Schmidbaur. Gold Bull. 1990, 23, 11. 19. C. S. W. Harker, E. R. T. Tiekink. Acta Ciystallogr., Sect. C: Cryst. Struct. Commun. 1991, 47, 878. 20. M. Yam, J. H. Chong, C.-W. Tsang, B. 0. Patrick, A. E. Lam, D. P. Gates. lnorg. Chem. 2006, 45, 5225. 21. R. Usón, A. Laguna, M. Laguna. lnorg. Synth. 1989, 26, 85. 22. Computer program: SAINT V. 7.03A ed. BrukerAXS Inc., Madison, WI. (1 997-2003). 23. Computer program: SHELXTLV. 5.1 ed. BrukerAXS Inc., Madison, WI. (1997).  References start on page 113  115  Chapter 6  Inorganic/Organic Hybrid GoIdQ)-containing Micelles*  6.1  Introduction  Living polymerization is an invaluable tool to form controlled polymer structures. 2 For ’ 1 example, living polymerization provides a facile method of preparing AB block copolymers starting with the polymerization of monomer A. Once the feedstock for polymer A is consumed, the monomer for polymer B is introduced to the reaction mixture. The living chain of A initiates the polymerization of the newly introduced monomer, subsequently forming the AB block copolymer. When polymers A and B have different physical properties (eg. solubility, glass transition temperature (Tg), intermolecular interactions), the resulting block copolymer has hybrid properties that are unattainable from homopolymers. 34 Our group is particularly interested in the solution self-assembly of AB block copolymers, where the blocks have different solubilities. Dissolving the copolymers in a solvent in which one block would dissolve but the other would not (known as a block selective solvent) can lead to macrostructure formations such as micelles, rods or vesicles. 5 Micelles, for example, consist of AB block copolymers that have assembled into a sphere consisting of two domains: the core comprised of the insoluble blocks and the corona formed from the soluble blocks (see Figure 6.1).6 Applications for polymers that form ordered assemblies in solution include: surfactants, drug-delivery systems, and nano reactors. 7-12  * A portion of this chapter has been published as a preliminary communication and is reproduced with permission. Kevin J. T. Noonan, Bronwyn H. Gillon, Vittorlo Cappello, and D. P. Gates, “Solution SelfAssembly of Isoprene-Phosphaalkene Block Copolymers: Macromolecular Templates for Tailor Made Gold(I) Nanostructures,”Journal of American Chemical Society, 130 (39), 12876—1 2877, 2008. Copyright 2008 American Chemical Society.  Chapter 6  116  I I I I  Corona (soluble Core (insoluble  A  B ••••••  Dissolve in a solvent in which blockAissolubleand B is insoluble  AB block-copolymer  I I  I  Cross-section of a micelle Figure 6.1 The solution self-assembly of an AB block copolymer to form a macromolecular structure (shown: cross-section of a spherical micelle). So far, most work on the preparation of block copolymers through living polymerization is limited to organic systems. Living polymerization of inorganic monomers is a comparatively new area of interest and opens the door to novel inorganic-organic hybrids. 1324 Recently, examples of these types of hybrid polymers exhibiting solution self-assembly have been reported. 2329 Recently, the living polymerization of phosphaalkenes was discovered by Kevin Noonan in our group, thereby establishing an innovative route to phosphorus-containing block copolymers. ° 2 To date, only block copolymers (6.3) prepared from styrene (6.1) and phosphaalkene 6.2 have been prepared (see Scheme 6.1). Unfortunately, polystyrene (PS) and poly(methylenephosphine) (PMP) have similar solubility properties since they are both soluble in polar organic solvents such as 2 CI and THF and are both insoluble in non-polar solvents CH (eg. n-hexanes) and protic solvents such as H 0 and MeOH. Therefore, PS—b—PMP polymers 2  are not suitable candidates for solution self-assembly studies. The search for a different A-block polymer with reasonable solubility in non-polar solvents led to the preparation of polyisoprene block-poly(methylenephosphine) (PlmbPMPn). Polyisoprene (P1) is soluble in linear aliphatics whereas PMP is not. Herein, the preparation of two block copolymers, PImbPMPn (m =308, n References start on page 130  Chapter 6 =  46; and m  117 =  222, n  =  77) and the self-assembly of these novel macromolecules into micelles  in P1 block selective solvent are reported.  E 1  n-BuLi 25°C, THF  LPSj_Li 4 nBu  1 Ph  I  1. n MesP=CPh 2 (6.2) 25 °C THF n-Bu-PS 2. MeOH m  PS-b-PMP  Scheme 6.1 6.2 Results and Discussion  Our objective was to determine the possibility of forming micelles in a block selective solvent with the block copolymers PlmbPMPn. To ascertain whether the formation of selfassembled structures occurred, transmission electron microscopy (TEM) and dynamic light scattering (DLS) were employed. Good contrast for TEM requires the presence of large atoms (for example, transition metals) in specific domains. The phosphorus atoms in the PMP block can be exploited through metallation with gold(l). Moreover, the block copolymer PlmbPMPn would provide a template to organize well-defined gold nanostructures. In chapter 5, I showed that homopolymer 6.4a and its model compound 6.4b were easily complexed to gold(l) through a simple ligand substitution reaction with (tht)AuCl (tht  tetrahydrothiophene) resulting in gold-  containing polymer 6.5a and phosphine 6.5b, respectively. 30 The larger scattering power of gold-containing domains (PMPAu) compared to the domains of the organic P1 provide sufficient contrast for TEM images. As a result, the domains containing gold can be located because they will appear darker than the organic domains. In addition to simply using gold as a contrast agent for TEM imaging, the possibilities to utilize the metal atoms are endless. For example, the gold(l) can be reduced to gold(O) to form PImbPMPn stabilized gold nanoparticles or to prepare gold nanowires.  References start on page 130  Chapter6  118 CI  r  Phi  I  R-1--P—C---j-H  I I LMes Phjn  n (tht)AuCI CI RT CH , 2 -n tht  6.4a: n>1, R=n-Bu 6.4b:n=1, R=Me  6.2.1  rAu Phi .1. R-{--P—C---j-H  I  [Mes Ph]n 6.5a: n> 1, Rn-Bu 6.5b:n=1, R=Me  The preparation of PImbPMPn block copolymers 6.9a (m = 308, n = 46) and 6.9b  (m = 222, n = 77) The block copolymers PlmbPMPn were prepared through the successive anionic polymerization of isoprene 6.6 and phosphaalkene 6.2. To prepare 6.9a (m = 308, n = 46), a substoichiometric amount of n-BuLi (0.3%) was added quickly to a THE solution of isoprene. The reaction mixture was stirred for 45 minutes. Subsequently, a small amount of the reaction mixture (containing lithiated P1 6.7) was removed and dropped into MeOH (50 mL). The resulting organic polymer 6.8 precipitated with MeOH as a white solid. After isolation, the polyisoprene sample 6.8 was analyzed by triple detection GPC (M = 21 000 g mo1 , PDI = 1 1.02). A polyisoprene chain with a molecular weight of 21 000 g mo1 1 has 308 monomer repeat units. Since synthetic polymers are mixtures with a distribution of chain lengths, 308 repeat units is just an approximation. Also, the uncertainty in the GPC analysis for the sample is ±2000 g 1 or 30 repeat units. For illustrative purposes, the P1 block will be treated as if it were exactly mo1 308 repeat units in order to more easily discuss the differences in the polymer samples 6.9a and 6.9b.  A solution of MesP=CPh 2 6.3 in THE was added to the remaining reaction mixture containing living poly(isoprenyl) macroinitiators 6.7. The reaction mixture was stirred for 12 hours and then treated with MeOH. 31 P NMR spectroscopy was employed to confirm that the  phosphaalkene monomer 6.3  (&lp  = 233) was completely consumed. The block copolymer 6.9a  showed a broad resonance at —5 ppm. The polymer was precipitated from the crude reaction  References start on page 130  Chapter6  119  mixture by adding MeOH (100 mL). After a second precipitation of a THF solution with MeOH, the product was isolated as a yellow powder in high yield (87%). After drying in vacuo, 6.9a was analyzed by GPC-LLS (M  =  35600 g moF , PDI 1  =  1.03) and determined to have approximately  46 repeat units in the PMP block, and therefore, is approximately 10 mol % PMP.  EI 1I  n-BuLi  m  25°C, THF  mMesPhn  m 6.6  6.7  PImbPMPn 6.9a (m = 308, n = 46) 6.9b (m = 222, n = 77)  MeOH  n-Bu  P1  Ph 1 I  1. n MesP=CPh 2 (6.2) 25 °C THF I n..Bu_t[PI 2. MeOH  H  Urn 6.8  The block copolymer with higher phosphorus content 6.9b (m  =  222, n  =  77) was  prepared in analogous fashion to 6.9a. Before the addition of the phosphaalkene monomer 6.2, an aliquot was removed from the reaction mixture (6.7 in THE) and was quenched with and precipitated with MeOH. After drying, triple detection GPC data suggested P1 6.8 had approximately 222 repeat units (M  =  15 100 g moM, PDI  =  1.06). To the remaining reaction  mixture, a solution of phosphaalkene 6.2 in THE was added. After being stirred for 12 h and subsequent workup of the reaction, the final block copolymer 6.9b was isolated and analyzed by GPC-LLS (M  =  39 400 g mor ; PDI 1  =  1.06). Therefore, 6.9b has ca 77 repeat units in the PMP  block corresponding to 26 mol % PMP.  References start on page 130  Chapter 6 6.2.2  120  Coordination of block copolymers to gold(I), 6.lOa and 6.lOb The PMP blocks are repeating phosphine units that can be readily coordinated to gold(I)  moieties. A solution of 6.9a (m  308, n  =  46) in 2 CI was treated with a solution of (tht)AuCI CH  in 2 CI and stirred for 1 h. Afterward, an aliquot was removed for analysis by 31 CH P NMR spectroscopy. Importantly, the resonance for the free block copolymer  31p = 6 (  —  5 ppm) was not  observed and a new resonance at 25 ppm appeared and is assigned to 6.lOa. In comparison to the homopolymer &4a and its model compound 6.4b, similar downfield shifts were observed (homopolymer 6.4a vs. 6.5a: A6  =  32; model compound 6.4b vs. 6.5b: M  copolymers 6.9a vs. 6.lOa: A5  30). The volatiles were removed in vacuo to afford the  =  39; block  metallated polymer 6.lOa as a yellow solid. Further characterization of 6.lOa was gathered using triple detection GPC-LLS (M  =  45000 g mo1 , PDI 1  =  1.14). The 10600 g mor’ increase  in molecular weight after coordination (from 35 600 to 45 000 g  ) is consistent with that 1 mor  expected for the coordination of AuCI moieties at phosphorus  corresponding well with the  —  approximately 50 P atoms in the backbone.  r  Phi  F  I  n-Bu-f-Pl  I  I I P—C--f-H I  I  Ph] m Mes  L  ,  Cl Au Phi  n (tht)AuCI  n-Bu-f-Pl  25°C, DCM -n tht  I  L  m  P—C—f-H I I Mes Ph]  PImbPMPn  PImb(PMPAU)n  6.9a (m = 308, n = 46) 6.9b (m = 222, n = 77)  6.lOa (m = 308, n = 46) GlOb (m = 222, n = 77)  Analogous to the preparation of 6.lOa, the preparation of gold-containing block copolymer 6.lOb involved the addition of (tht)AuCI to 6.9b (m  =  222, n  =  77) in 2 CI The CH .  resulting gold-containing polymer was analyzed by GPC-LLS and determined to have an M 47 100 g mor 1 (PDI  =  1.15) tallying to an increase of 7 700 g moF 1 or the addition of  approximately 30 AuCI units.  References start on page 130  Chapter 6  6.2.3  121  Solution self-assembly of gold-containing block copolymers Plmb (PMPAu) With the two metallated block copolymers in hand, solvent conditions in which the  polymers would assemble into macromolecular structures were sought. Additionally, the differences in the solubilities of the two block copolymers will be exploited in order to explore the possibility of controlling the structures of the self-assemblies. Both PMP and P1 are soluble in polar solvents like THE and 2 CI but only P1 is soluble in aliphatic solvents. Gold-containing CH polymer 6.lOa (m  =  308, n  46) has a relatively shorter PMP block at approximately 10 mol %  of the polymer. This block copolymer is expected to be more soluble in non-polar solvents than 6.lOb (m  =  222, n  77) with —30 mol % PMP. The nature and size of the self-assembled  structures of 6.lOa and 6.lOb were assessed using TEM and confirmed by DLS.  Initially, dilute solutions of 6.lOa were prepared in a variety of aliphatic solvents. Promising results were achieved by employing dilute solutions of n-heptane. With the relatively long polyisoprene block, 6.lOa was completely dissolved in n-heptane (3 mg /4 mL). A 3 jL aliquot of the dilute solution was dropped onto a copper TEM grid coated with Formvar (a grid support film) and allowed to evaporate to dryness. Clearly visible in the TEM images (see Figure 6.2 (a) and (b)), are oblong-shaped micelles with lengths ranging from 15 nm to 150 nm (mean =  53 nm; a  =  25 nm). In a sample of 30 micelles taken from overall 1/3 of the image, the widths  have a relatively narrow range of 15 to 30 nm with an average of 21 nm (a  =  4). Analysis of the  solution by DLS spectroscopy showed that in solution the species had hydrodynamic radii (Rh) of 94 nm at 25 °C confirming the presence of macromolecular structures. The sizes are larger than those measured by the TEM images. In the TEM images, the size of the micelles where gold is present, i.e. the core containing PMP, can only be measured. The DLS measures the entire micelle, containing both the PMP and P1 blocks.  References start on page 130  Chapter 6  122  c  -  •  •  ‘•-,  •,--  ;:100 nm  ••  ;:  •,  .1  ;\  •  • •‘‘•  Figure 6.2 TEM images of 6.lOa (m = 308, n = 46): a) n-heptane (3 mg /4 mL), magnification 1x10 ; b) n-heptane (3 mg/4 mL), magnification 2x10 5 ; C) n-heptane (2mg /4 5 mL), magnification 5x1 o; d) n-heptane (2 mg / 4 mL), magnification 2x1 o; e) n-heptane:THF (7:1)(3 mg/4 mL).  References start on page 130  Chapter 6  123  To ensure that these oblong structures (with average dimensions of 55 nm x 21 nm) were not the result of aggregation during the evaporation process, another more dilute solution in n-heptane (2 mg /4 mL) has been prepared. The TEM images (Figure 6.2 (c) and (d)) demonstrate that the oblong shapes are still present though possess somewhat smaller in dimensions. The widths are comparable to the more concentrated sample, ranging from 10 to 30 nm (mean  =  19 nm;  y=  6 nm). However, the lengths of the macromolecular structures are  noticeably shorter with an average of 34 nm (a  =  19 nm). Likely, the larger structures in Figure  6.2 (a) and (b) are due to smaller micelles aggregating into larger masses.  Finally, to provide conclusive evidence that the structures were a result of solution selfassembly, 3 mg of block copolymer polymer 6.lOa were dissolved in 4 mL of a mixture of n heptane:THF (7:1). The small amount of THE should solubilize the PMP block thereby destroying the micelles. Figure 6.2 (e) unmistakably shows the lack of large structures as the gold atoms are fairly evenly distributed throughout the image.  The block copolymers 6.lOa have been shown to form well-defined nanostructures from self-assemblies in a P1 block selective solvent. In particular, oblong-shaped micelles (with lengths averaging 50 nm and widths of 20 nm) have been observed. Now, the investigation of the possibility of controlling the shape of the micelles, by controlling the proportion of the two blocks while maintaining a similar molecular weight distribution, will be explored. The block copolymer 6.lOb (m  =  6.lOa (m  46) was prepared and therefore expected to have a different assembly in  308, n  222, n  =  77) that has a shorter P1 block and a longer PMP block than  solution. However, with a higher PMP content, block copolymer 6.lOb was not soluble in n heptane alone at the desired concentration (3 mg / 4 mL). A small amount of THF was required to completely solubilize the sample (0.5 mL for every 3.5 mL of n-heptane). See Figure 6.3 (a) and (b) for the TEM images of the evaporated samples. In the solvent mixture, the block copolymer 6.lOb also demonstrated the ability to self-assemble into micelles, albeit from slightly References start on page 130  Chapter 6  124  different solvent conditions, with a different appearance to those from the P1 rich block copolymer 61Oa. Micelles formed from 6.lOb in the solvent mixture are generally oblong in shape with a width of 18 nm (c (mean  =  97 nm; c  =  =  3 nm). These cylindrical micelles have lengths of up to 170 nm  43 nm). The species in solution were found to have an average  hydrodynamic radius of 75 nm at 25°C by DLS thereby demonstrating that the micellar structures are retained in solution. To confirm the reproducibility of this remarkable selfassembly, a second sample of 61Ob was analyzed in an analogous fashion (TEM: Figure 6.3 (c) and (d)).  a).-.  b)  •o..  .1  1 .  ‘F  •••‘%  (  p  F  I.  —  (  /•  .1  -I 4  —b..  -  .  .-..  -  _%•  __.,  lOOnm.  ‘  .(  pl  c)  f  ::  •  100 nrn  lOOnm  Figure 6.3 TEM images of 6.lOb (m = 222, n = 77) n-heptane:THF (7:1) (3mg /4 1: a) magnification 1x10 ; b) magnification 2x10 5 ; Trial 2: c) magnification 1x10 5 ; d) 5 magnification 2x1 5•  Trial  References start on page 130  Chapter 6  125  The shapes of the micelles from 6.lOb can be interpreted in a couple of ways from the TEM images. Either, the micelles are spherical in shape which have self-organized into necklace-like linear aggregates. Another possibility is that under the solvent conditions used to obtain the TEM images in Figure 6.3, the boundary between spherical and cylindrical micelles has been unexpectedly discovered and therefore both types are observed (see Figure 6.4 (b)). Further experiments to determine the types of micelles are ongoing. Regardless, the observed assemblies are believed to be due primarily to the polymer structure and not the solvent conditions. Recall that a sample of 6.lOa (m  =  308, n  =  46) in a mixture of n-heptane and THF  (7:1) was analyzed under analogous conditions and found no evidence of macromolecular structures from the TEM images. Gold-containing spherical micelles that self-organize into necklace-like aggregates are known though with organic block copolymers and reduced gold. 31  (a) Spherical Micelles  (b) Cylindrical Micelles  * Figure 6.4 Sketches of two basic structural motifs for spherical micelles and (b) cylindrical micelles.  in dilute solution: (a)  6.3 Conclusion  New hybrid inorganic/organic block copolymers (Plm—PMPn) with varying m:n ratios were prepared. The functionality of the PMP block was exploited by coordinating gold(l) moieties to the backbone P atoms resulting in new gold-containing polymers. Furthermore, the solution self assembly of the functionalized block copolymers was investigated and the resulting novel References start on page 130  Chapter 6  126  nanostructured assemblies with interesting shapes were characterized by TEM and DLS. In P1specific solvents, P1m (PMPAu) co-polymers will assemble into micelles with a PMPAu core and P1 corona. The micelles varied in shapes (from spherical to oblong) sizes according to the block ratio (m:n). These materials are excellent candidates for applications in nanotechnology, such as the preparation of gold nanowires after reduction of the Au(l) atoms.  6.4 Experimental  6.4.1  Materials and General Procedures All manipulations of oxygen- and/or moisture-sensitive compounds were performed  under a nitrogen atmosphere using standard Schlenk and/or glovebox techniques. Hexanes and dichloromethane were deoxygenated with nitrogen and dried by passing through a column containing activated alumina. THE was freshly distilled from sodium/benzophenone ketyl. Distilled methanol was degassed prior to use. 2 CI was purchased from Cambridge Isotope CD Laboratories and were dried over molecular sieves (3  A). n-BuLi (1.6 M in hexanes) and n  heptane were purchased from Aldrich and used as received. Alkyllithium reagents were titrated prior to use. Isoprene was purchased from Aldrich and distilled prior to use. MesPCPh 2  (6.3)32  and (tht)AuCI 33 were prepared following literature procedures.  P NMR spectra were recorded on BrukerAV300 orAV400 spectrometers at room 31 temperature. Chemical shifts for 31 P NMR spectra are reported relative to 4 P0 as an external 3 H standard (85% in H 0, ö 2  0).  Molecular weights were estimated by triple detection gel permeation chromatography (GPC-LLS) using a Waters liquid chromatograph equipped with a Waters 515 HPLC pump, Waters 717 plus autosampler, Waters Styragel columns (4.6 x 300 mm) HR5E (2000-4 000 000), HR4 (5000-500 000), and HR2 (500-20 000), Waters 2410 differential refractometer ( = References stan on page 130  Chapter 6  127  940 nm, 40 °C), Wyatt tristar miniDAWN (laser light scattering detector operating at  =  690 nm),  and a Wyatt ViscoStar viscometer. A flow rate of 0.5 mL mm-I was used, and samples were dissolved in THE (Ca. 2 mg mL-1).  TEM images were collected with the UBC Biolmaging Eacility Hitachi H7600 TEM (120kV tungsten filament) equipped with a side mount AMT Advantage (1 mega-pixel) CCD camera (Hamamatsu ORCA). The sample solutions were deposited on a Eormvar-coated TEM grid and allowed to evaporate to dryness.  DLS experiments were performed with a Coulter N4 Plus DLS instrument equipped with a 10-mW helium-neon laser (A  =  632.8 nm) and thermoelectric temperature controller.  Measurements were taken at a 90° scattering angle in a 3 x 3-mm quartz cuvette on solutions that had been equilibrated at 25 °C. Particle sizes were estimated by SDP weight and intensity analyses.  6.4.2  Preparation of 6.9a (m  =  308, n  =  46)  To a stirred solution of isoprene (0.68 g, 0.010 mol) in THE (0.5 mL) was added 20 iL of n-BuLi (1.36 M, 0.027 mmol) in hexanes via 100 p.L syringe. The reaction mixture turned yellow immediately and was stirred for approximately 45 mm. A drop of the reaction mixture was removed and added to 50 mL of methanol. The organic polymer 6.8 precipitated out of the solution as a white solid. After isolation, polyisoprene 68 was dried in vacuo and analyzed by using GPC-LLS (M  =  21 000 (± 2000) g mor , PDI 1  =  1.02, dn/dc  =  0.129). To the reaction  mixture containing the active poly(isoprenyl lithium) species, a solution of MesP=CPh 2 (0.285 g, 0.901 mmol) in a minimal amount of THE was added. The solution immediately turned red and was allowed to stir for 24 h at which point the reaction mixture was almost black in colour. The solution was added dropwise into methanol (100 mL) and filtered. A second precipitation was performed from a concentrated solution of 6.9a in THE into MeOH (100 mL). Volatiles were References start on page 130  Chapter 6  128  removed in vacuo at 60 °C for several hours. The product was isolated as a yellow powder. Yield  =  0.844 g (87%).  P NMR (THE, 162 MHz): 31 PDI  1.03 (±0.01), dn/dc  6.4.3  =  —5 ppm. GPC-LLS (THE): M  =  35 600 (± 300) g mor , 1  0.134.  =  Preparation of 6.9b (m  =  222, n  =  77)  To a stirred solution of isoprene (0.68 g, 0.010 mol) in THE (0.5 mL) was added 20 jiL of n-BuLi (1.36 M, 0.027 mmol) in hexanes via 100 jtL syringe. The reaction mixture turned yellow immediately and was stirred for approximately 45 mm. A drop of the reaction mixture was removed and added to 50 mL of methanol. The polymer 6.8 precipitated out of the solution as a white solid. After isolation, polyisoprene 6.8 was dried in vacuo and analyzed by using GPC-LLS (M  15 100 (± 1 300), PDI  1.06, dn/dc  =  0.129). To the reaction mixture  =  containing the active poly(isoprenyl lithium) species, a solution of MesP=CPh 2 (0.520 g, 0.0016 mol) in a minimal amount of THE was added. The solution immediately turned red and was allowed to stir for 24 h. The solution was added dropwise into methanol (2 x 100 mL) and filtered. Volatiles were removed in vacuo at 60 °C for several hours. The product was isolated as a yellow powder. Yield  =  0.86 g (72%).  P NMR (THE, 162 MHz): 31 PDI  =  6.4.4  1.06 (±0.07), dn/dc  =  —  5 ppm. GPC-LLS (THE): M  39 400 (± 300) g mo1 , 1  0.157.  Preparation of gold-containing 6.lOa A solution of 6.9a (98.9 mg, M  =  35 600, PDI  =  1.03) in 2 CI (5 mL) was treated with CH  a solution of (tht)AuCl (33 mg, 103 mmol) in 2 CI (5 mL). After being stirred for 1 h, an aliquot CH was removed and analyzed by 31 P NMR spectroscopy  ( = 25 br). The solvent was removed in References start on page 130  Chapter 6  129  vacuo resulting in a light yellow solid. The product was dissolved in toluene (3 mL x 2) followed  by hexanes (5 mL x 2) and dried in vacuo to ensure the removal of tht. The product was dried overnight in vacuo. Yield  =  119 mg (97%). TEM and DLS sample concentrations: 2.9 mg in 4  mL n-heptane.  P NMR (THF, 162 MHz): 31 PDI  =  6.4.5  1.10 (±0.07), dn/dc  =  =  28 - 21 (broad). GPC-LLS (THF): M  0.137. DLS: Rh  =  =  42 000 (±1 000),  95 nm.  Preparation of gold-containing 6.lOb To a stirred solution of block copolymer 6.9b (kn491) (50 mg, M  =  37 300, PDI  =  1.06)  in 2 CI (3 mL) was added (tht)AuCI (25 mg, 78 mmol) in 2 CH CI (2 mL). The solvent was CH removed in vacuo resulting in a yellow solid. The product was dissolved in a minimal amount of CI and precipitated with hexanes. Toluene (3 mL x 2) followed by hexanes (5 mL x 2) were CH 2 added to the product and subsequently removed in vacuo to ensure the removal of tht. The product was dried overnight in vacuo. Yield  =  54 mg (79 %). TEM sample: 3.1 mg in 0.5 mL  THE and 3.5 mL n-heptane.  P NMR (121.5 Hz, THE): 31  PDI  =  1.15(2), dn/dc  =  =  0.155. DLS: Rh  25 (broad). GPC-LLS (THF): M =  =  47 100(1 000) g mo1 , 1  75 nm.  References start on page 130  Chapter 6 6.5  130  References  1. G. Odian, Principles of Polymerization. Wiley & Sons: New York, 1991. 2. 0. W. Webster. Science 1991, 251, 887. 3. G. Riess. Prog. Polym. Sci. 2003, 28, 1107. 4. S. B. Darling. Prog. Polym. Sci. 2007, 32, 1152. 5. I. W. Hamley. Soft Matter2005, 1,36. 6. I. W. Ham ley, Block Copolymers in Solution: Fundamentals and Applications. Wiley: 2005; p 300. 7. K. Kita-Tokarczyk, J. Grumelard, T. Haefele, W. Meier. Polymer 2005, 46, 3540. 8. L. F. Lindoy, I. M. Atkinson, Self-Assembly in Supramolecular Systems. 1st ecL; Royal Society of Chemisty: 2001; p 223. 9. R. E. Cohen. Curr. Opin. Solid State Mater. Sci. 1999, 4, 587. 10. I. W. Hamley. Nanotechnology 2003, 14, R39. 11. M. Lazzari, M. A. Lopez-Quintela. Adv. Mater 2003, 15, 1583. 12. C. Park, J. Yoon, E. L. Thomas. Polymer 2003, 44, 6725. 13. C. Kioninger, M. Rehahn. Macromolecules 2004, 37, 1720. 14. M. Tanabe, I. Manners. J. Am. Chem. Soc. 2004, 126, 11434. 15. J. Bauer, N. Husing, G. Kickelbick. J. Polym. Sc, Part A: Polym. Chem. 2004, 42, 3975. 16. S. Ndoni, M. E. Vigild, R. H. Berg. J. Am. Chem. Soc. 2003, 125, 13366. 17. D. A. Rider, K. A. Cavicchi, K. N. Power-Billard, T. P. Russell, I. Manners. Macromolecules 2005, 38, 6931.  18. T. J. Peckham, J. A. Massey, C. H. Honeyman, I. Manners. Macromolecules 1999, 32, 2830. 19. L. Cao, I. Manners, M. A. Winnik. Macromolecules 2001, 34, 3353. 20. K. J. T. Noonan, D. P. Gates. Angew. Chem. Int. Ed. 2006, 45, 7271.  References start on page 130  Chapter6  131  21. M. Roerdink, T. S. van Zanten, M. A. Hempenius, Z. Zhong, J. Feijen, G. J. Vancso. Macromol. Rapid Commun. 2007, 28, 2125. 22. Z. Wang, G. Masson, F. C. Peiris, G. A. Ozin, I. Manners. Chem.-Eur. J. 2007, 13, 9372. 23. X.-S. Wang, M. A. Winnik, I. Manners. Macromol. Rapid Commun. 2002, 23, 210. 24. T. Sanji, K. Takase, H. Sakurai. J. Am Chem. Soc. 2001, 123, 12690. 25. J. F. Gohy, B. G. G. Lohmeijer, A. Alexeev, X. S. Wang, I. Manners, M. A. Winnik, U. S. Schubert. Chem. Eur. J. 2004, 10, 4315. 26. H. R. Ailcock, E. S. Powell, Y. Y. Chang, C. Kim. Macromolecules 2004, 37, 7163. 27. A. H. Gabor, E. A. Lehner, G. P. Mao, L. A. Schneggenburger, C. K. Ober. Chem. Mater. 1994, 6, 927. 28. D. A. Rider, I. Manners. Polymer Reviews 2007, 47, 165. 29. H. Wang, M. A. Winnik, I. Manners. Macromolecules 2007, 40, 3784. 30. B. H. Gillon, B. 0. Patrick, D. P. Gates. Chem. Commun. 2008, accepted. 31. 5. Abraham, C. S. Ha, C. A. Batt, I. Kim. J. Polym. ScL, Part A: Polym. Chem. 2007, 45, 3570. 32. M. Yam, J. H. Chong, C.-W. Tsang, B. 0. Patrick, A. E. Lam, D. P. Gates. lnorg. Chem. 2006, 45, 5225. 33. R. UsOn, A. Laguna, M. Laguna. lnorg. Synth. 1989, 26, 85. 34. C. Jackson, Y. J. Chen, J. W. Mays. J. AppI. Polym. Sc!. 1996, 61, 865.  References start on page 130  132  Chapter7  Overall Conclusions and Future Work  7.1 Summary of Thesis Work  Shortly before I had joined, the Gates group had successfully polymerized PtC bonds for the first time through both anionic and radical methods. 1 The resulting poly(methylenephosphine)s 7.1 were characterized mainly by convential GPC and NMR spectroscopy. Some questions remained about these novel phosphorus-containing polymers. In particular, we wanted to know if the mechanism of anionic polymerization for phosphaalkenes was analogous to that for alkenes. We were interested in the site of initiation and the nature of the endgroups. Additionaly, we wanted to functionalize poly(methylenephosphine)s at the P atom with transition metals.  F I  L  Phi  I  I  Mes Ph 7.1  The initiation and termination steps in the anionic polymerization of P=C bonds have been modeled and are reported in Chapter 2.2 The initiation step was investigated through the stoichiometric reaction of MesP=CPh 2 (7.2) with RLi (R  =  Me or n-Bu). The addition was highly  regioselective with the formal attack of R at phosphorus. The termination step in the anionic polymerization of 7.2 was simulated by the subsequent, in situ addition of electrophiles (H from 0 or MeOH; Me from Mel; (NEt 2 H P from CIP(NEt ) 2 ; or Me ) 2 RSi from Me 2 HSiCI or Me 2 SiCI). 3 As a result, five novel tertiary phosphines (7.3a-e) and one diphosphine (7.3f) were prepared and function as models for poly(methylenephosphine)s. References start on page 135  Chapter 7  133 Ph / P=c \ / Mes Ph  RLi  Ph R_P_C:eeLi  I  I  Ph EX  R—P—C—E  I  -LiX  Mes Ph  7.2  I  Mes Ph 7.3a: 7.3b: 7.3c: 7.3d: 7.3e: 7.31:  R= R= R= R= R= R=  Me, E=H; Me, E = Me; n-Bu, E = H; Me, E = P(NEt ; ) 2 Me, E = SiMe ; 3 Me, E = S1HMe 2  In Chapter 3, I showed that the chain growth step in the anionic polymerization mechanism for P=C bonds proceeds in analogous fashion to olefins. 3 The oligomeric products were characterized by MALDI-TOF MS from which endgroups were observed. However, analysis by MALDI-TOF MS resulted in the observation of fragments of the oligomers. Addtionally, I showed that high temperatures were not necessary; previous work on the polymerization of phosphaalkene 7.2 with MeLi (5%) in a minimum of solvent required a temperature of 150 oCi Anionic oligomerization of phosphaalkenes can be extended to the use  of another initiator (n-BuLi) and to other monomers with functional groups (F and OMe). Ar / RL1 P=C \ / Et 0 2 , -78 °C Mes Ph  r  Ar R—P—C—Li  I  2or3equiv3.1  I  _Li 1 R-f_—_  0 2 Et  Mes Ph  1 Ar  LMeS  7.2:Ar Ph 7.2a: Ar = p-C OMe 4 H 6 7.2b: Ar = p-C F 4 H 6  Phjn  MeOH or 0 2 H  ro  An 11111  R+-P—C-+H  I I  0 2 H  I I  LMeS PhJn 7.4a: Ar = Ph; R = Me 7.4a: Ar = Ph; R = n-BuLl  F  Ar  R-{-P-C*H  LMs  Ph]n  7.4b: Ar = p-C OMe; R = Me 4 H 6 7.4c: Ar = p-C F; R = Me 4 H 6  Chapter 4 describes the coordination of poly(methylenephosphine) to group 6 metal carbonyl complexes. Phosphine 7.3 has been used as a model for 7.1 and was used to develop  References start on page 137  Chapter 7  134  a route to metal-containing polymers. As a result, phosphine-metal complexes 7.5a, 7.5b and 7.5c were prepared through the thermally induced substitution of a CO group. Partial metallation of polymer 7.1 with W, Mo and Cr was achieved. The objective was to achieve high metal loading of the polymer 7.1 with the hopes of preparing useful metal-containing materials or ceramic precursors. We now are certain that phosphorus-metal bonds can be formed. However, for total metallation of polymer 7.1, a less sterically hindered, larger metal center should be selected. M 5 (CO) Phi F Me-I—P-C--i-H LMesPhin 7.5a: n=1; M =W 7.5b: n= 1; M= Mo 7.5c: n=1; M =Cr 7.5d: n> 1; M =W 7.5e: n> 1; M = Mo 7.5f: n>1; M =Cr  Complexation of the polymer 7.1 and its model compound 7.3a to Au(l) is described  in  Chapter 54 The complexation was easily extended to polymer 7.1. I showed that most of the P atoms in the polymer backbone were coordinated to gold(l). Cl Au  Et n-Bu  Phi  P—C  [Mes 7.6a: 7.6b:  H  Phjn  n n  >  I 1  We successfully prepared new hybrid inorganic/organic amphiphilic block copolymers (PImbPMPn). Utilizing the straightforward functionalization of poly(methylenephosphine)s 7.1 with Au(l), we easily coordinated the novel block copolymers to gold(l). Furthermore, the solution self-assembly of the functionalized block copolymers has been investigated resulting in  References start on page 137  Chapter 7  135  assemblies with interesting shapes. The micelles varied in shapes (from spherical to cylindrical) sizes according to the block ratio (m:n).  r  P—C—j-H  L  m MsPhj  n-ButPl  Plm&(PMPAU)n  7.2 Future Work  7.2.1  Uses for model compounds of poly(methylenephosphine) The end-group functionalization of the model compounds can be extended to the  polymer. Using functional electrophiles in the termination step of the polymerization would access other types of block copolymers: telechelic polymers.  7.2.2  The preparation of polymer with high tungsten-content A different route for tungsten-containing polymers may result in higher W content could  be used as a precursor to WP ceramic materials. Some preliminary investigations have suggested that the anionic initiation of complexes of the type 7.7 is possible with MeLi. Sterically unencumbered phosphaalkenes have been prepared as complexes to tungsten carbonyl 5 fragments.  6  This could also be a route to poly(methylenephosphine)s with smaller substituents  (7.9).  References start on page 137  Chapter 7  136 W 5 (CO)  W 5 (CO)  R P=C R’  R”  MeLi R=Mes R’=R’=Ph  Ph  Me—P—C—Li I I MesPh  (CO)W  El. i  n-Bu---f-P—C-j-H  [F R”j 7.9  7.2.3  Gold-containing micelles •  Extend the m:n ratio of the block copolymer, PImbPMPn, to further investigate the effect of the ratio on the shape of the self-assembled products.  •  Reducing the gold(I) cores in the micelles to gold(O) may form poly(methylenephosphine)-stabilized gold nanoparticles useful in nanotechnology and catalysis. 7  7.3 Closing Remarks  The mechanism of anionic polymerization of P=C bonds was more deeply investigated through the synthesis and characterization of model compounds and short-chain oligomers. This thesis also contains the first reports of metal-containing poly(methylenephosphine)s. Although only moderate amounts of group 6 metals were incorporated into the homopolymer, evidence indicates that M-P bonds were formed. The homopolymers were shown to be much better ligands for gold(l). In fact, gold incorporation was extended to amphiphilic block  copolymers which were subsequently shown to form micelles of varying sizes.  References start on page 137  Chapter 7 7.4  137  References  1. C.-W. Tsang, M. Yam, D. P. Gates. J. Am. Chem. Soc. 2003, 125, 1480. 2. B. H. Gillon, K. J. T. Noonan, B. Feldscher, J. M. Wissenz, Z. M. Kam, T. Hsieh, J. J. Kingsley, J. I. Bates, D. P. Gates. Can. J. Chem. 2007, 85, 1045. 3. B. H. Gillon, D. P. Gates. Chem. Commun. 2004, 1868. 4. B. H. Gillon, B. 0. Patrick, D. P. Gates. Chem. Commun. 2008, 2161. 5. A. Marinetti, S. Bauer, L. Ricard, F. Mathey. Organometallics 1990, 9, 793. 6. L. Weber, M. Meyer, H. G. Stammler, B. Neumann. Organometallics 2003, 22, 5063. 7. M. C. Daniel, D. Astruc. Chem. Rev. 2004, 104, 293.  References start on page 137  

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