......................................................................................................................................... ii Preface ........................................................................................................................................... iv Table of contents ............................................................................................................................v List of tables.................................................................................................................................. ix List of figures .................................................................................................................................. x List of schemes ............................................................................................................................ xiv List of symbols .......................................................................................................................... xviii List of abbreviations .................................................................................................................. xix List of new compounds ................................................................................................................ xx Acknowledgements .................................................................................................................. xxiv Foreward ..................................................................................................................................... xxv 1 Early transition metal hydrides and ligand design ..................................................................1 1.1
Early transition metal hydrides .......................................................................................... 1 1.1.1
Overview ..................................................................................................................... 1 1.1.2
Scandium and yttrium hydride complexes .................................................................. 2 1.1.3
Zirconium and hafnium hydride complexes ............................................................. 12 1.2
Phosphinoamide ligands .................................................................................................. 18 1.2.1
Ligand design in the Fryzuk group ........................................................................... 18 1.2.2
Introduction to phosphinoamides .............................................................................. 20 1.2.3
Mononuclear transition metal phosphinoamide complexes ...................................... 24 1.2.4
Multimetallic phosphinoamide complexes ............................................................... 26 vi 1.3
Scope of thesis ................................................................................................................. 30 2 Phosphinoamide scandium and yttrium organometallic complexes ....................................32 2.1
Introduction ...................................................................................................................... 32 2.2
Phosphinoamide supported scandium and yttrium organometallics ................................ 34 2.2.1
Alkane-elimination route to scandium and yttrium complexes ................................ 34 2.2.2
Trisubstituted phosphinoamide scandium and yttrium complexes ........................... 35 2.2.3
Mixed alkyl-phosphinoamide complexes of scandium and yttrium ......................... 38 2.3
Ferrocene-linked phosphinoamides as supporting ligands for scandium ........................ 44 2.3.1
Ferrocene as a diamine linker in ligand design ......................................................... 44 2.3.2
Synthesis of a ferrocenyl diphosphinoamine ............................................................ 45 2.3.3
Synthesis of a ferrocenyl phosphinoamide scandium alkyl complex ....................... 46 2.3.4
Synthesis of a discandium dihydride complex .......................................................... 51 2.4
Conclusion ....................................................................................................................... 56 3 Tri(phosphinoamide) complexes of zirconium .......................................................................58 3.1
Introduction ...................................................................................................................... 58 3.2
Synthesis of phosphinoamide zirconium complexes ....................................................... 61 3.3
Synthesis of organometallic tri(phosphinoamide) zirconium complexes ........................ 67 3.4
Attempted hydrogenolysis of zirconium alkyls ............................................................... 70 3.5
Alternative approaches to hydride complexes ................................................................. 71 3.6
Synthesis of a zirconium phosphide complex .................................................................. 74 3.7
Conclusion ....................................................................................................................... 79 4 Ferrocene-linked phosphinoamide complexes of zirconium .................................................80 4.1
Introduction ...................................................................................................................... 80 vii 4.2
Synthetic route to ferrocenyl diphosphinoamide zirconium complexes .......................... 83 4.3
Synthesis of organometallic zirconium complexes .......................................................... 89 4.3.1
Synthesis and characterization of primary alkyl zirconium complexes .................... 89 4.3.2
Benzyl bonding modes in zirconium complexes ...................................................... 92 4.3.3
Attempted hydrogenolysis of dialkyl zirconium complexes .................................... 93 4.3.4
Synthesis of a zirconium complex containing β-hydrogens ..................................... 93 4.4
Isocyanide insertion reactivity with dialkyl zirconium complexes .................................. 97 4.4.1
Synthesis of iminoacyl complexes ............................................................................ 97 4.4.2
Isomerization from iminoacyl to an amido-alkene complex .................................. 100 4.5
Conclusions .................................................................................................................... 103 5 Electrochemistry of ferrocenyl diphosphinoamide complexes ...........................................105 5.1
Introduction .................................................................................................................... 105 5.2
Introduction to cyclic voltammetry ................................................................................ 106 5.3
Redox behavior in ferrocene-linked diphosphinoamide complexes .............................. 109 5.3.1
Redox behavior of fc(NPPr2)2H2 ............................................................................ 109 5.3.2
Redox behavior of fc(NPPr2)2Sc(CH2SiMe3)(THF) .............................................. 110 5.3.3
Redox behavior of fc(NPPr2)2ZrX2 (X = NMe2, CH2Ph) ...................................... 112 5.3.4
Synthesis and redox behavior of fc(NPPr2)2Li2 ..................................................... 114 5.3.5
Attempted synthetic strategies ................................................................................ 116 5.4
Conclusions .................................................................................................................... 117 6 Diversions and future directions............................................................................................118 6.1
Diversions with porphyrin-supported tantalum complexes ........................................... 118 6.2
Future work on tantalum porphyrin complexes ............................................................. 119 viii 6.3
Diversions synthesizing phosphine-bridged amidate ligands ........................................ 120 6.4
Alteration of the ferrocenyl diphosphinoamide ligand system ...................................... 122 6.4.1
Overview ................................................................................................................. 124 7 Experimental ...........................................................................................................................125 7.1
General procedures ........................................................................................................ 125 7.1.1
Laboratory equipment and procedures .................................................................... 125 7.1.2
Solvents ................................................................................................................... 125 7.1.3
Materials ................................................................................................................. 125 7.1.4
Instrumentation and methods of analysis ................................................................ 126 7.2
Synthesis of compounds ................................................................................................ 129 7.2.1
Complexes pertaining to Chapter 2 ......................................................................... 129 7.2.2
Complexes pertaining to Chapter 3 ......................................................................... 135 7.2.3
Complexes pertaining to Chapter 4 ......................................................................... 141 7.2.4
Complexes pertaining to Chapter 5 ..............................................................