UC San Diego UC San Diego Electronic Theses and Dissertations Title Isolation of Four-Coordinate Iridium(I) Monohydrides and the X-ray Crystal Structure of a Cobalt Tris-Isocyanide Alkane sigma-Complex / Permalink https://escholarship.org/uc/item/1b20p9sg Author Millard, Matthew David Publication Date 2013 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California UNIVERSITY OF CALIFORNIA, SAN DIEGO Isolation of Four-Coordinate Iridium(I) Monohydrides and the X-ray Crystal Structure of a Cobalt Tris-Isocyanide Alkane sigma-Complex A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Chemistry by Matthew David Millard Committee in charge: Professor Joshua S. Figueroa, Chair Professor Joseph M. O‘Connor Professor Nicholas C. Spitzer Professor F. Akif Tezcan Professor William C. Trogler 2013 Copyright Matthew David Millard, 2013 All rights reserved Ignature Page The dissertation of Matthew David Millard is approved, and it is acceptable in quality and form for publication on microfilm and electronically. Chair University of California, San Diego 2013 iii DEDICATION To my mother: for marrying the guy being chased by the cops while doing a wheelie on an orange motorbike up the street. iv EPIGRAPH Epig NEVER SAY NO TO A CHALLENGE Professor Karl O. Christe v TABLE OF CONTENTS Signature Page ......................................................................................................................... iii Dedication ................................................................................................................................ iv Epigraph .................................................................................................................................... v Table of Contents .................................................................................................................... vi List of Figures ........................................................................................................................ viii Lists of Schemes ...................................................................................................................... xv List of Tables........................................................................................................................ xviii List of Equations ..................................................................................................................... xx Acknowledgments ................................................................................................................. xixi Vita ...................................................................................................................................... xxivi Abstract of the Dissertation ................................................................................................ xxvi Chapter 1 Isolation, Characterization, and Reactivity of a Vaska–Type Iridium(I) Monohydride 1.1 Introduction ................................................................................................................... 1 1.2 The Annals of Reactive Intermediates Comprising the Formula HIrL3 ........................ 3 1.3 Rational Ligand Design: Synthesis of a C–H Activation Resistant Tri– Alkyl Phosphine ..................................................................................................................... 8 1.4 Synthesis and Characterization of a Four–Coordinate Iridium(I) Monohydride ........................................................................................................................ 13 1.5 Reactivity Studies of an Iridium(I) Monohydride ....................................................... 23 1.6 Topological Studies of Highly Strained 5–Membered Iridacycles ............................. 30 1.7 Reactivity Studies of an Anionic Iridium(I) Monohydride ......................................... 34 1.8 Conclusions ................................................................................................................. 37 1.9 Synthetic Procedures ................................................................................................... 30 1.10 Crystallographic Structure Determinations .................................................................. 48 1.11 References ................................................................................................................... 54 Chapter 2 Elucidating the Reactivity of Lewis Acidic Phosphinite Iridium Hydrides 2.1 Introduction ................................................................................................................. 60 2.2 Desire to Attenuate Metal-Based Electron Density in Four-Coordinate Iridium Monohydride Complexes ..................................................................................................... 60 2.3 Synthetic Access to a Phosphinite Analogue of LmAd ................................................. 63 2.4 VT NMR Studies of the Cyclometallated LoAd Complex (12) .................................. 68 2.5 Alkyl Anion Binding to an Iridium Phosphinite Complex .......................................... 73 2.6 Oxidative Behavior of Anionic Phosphinite Complexes Methyl (15) and n-Butyl (14) 77 2.7 Formation of Four-coordinate LoAd Anion Monohydrides .......................................... 79 2.8 Conclusions ................................................................................................................. 83 2.9 Synthetic Procedures ................................................................................................... 84 2.10 Crystallographic Structure Determinations .................................................................. 92 2.11 References .................................................................................................................... 96 Chapter 3 Coordination of Alkanes to an Unsaturated Cobalt Complex – an X–ray Crystallographic Endeavor 3.1 Introduction ................................................................................................................. 98 3.2 Synthetic Studies of a Cobalt Tris–Isocyanide Monoanion Complex ....................... 104 Mes2 3.3 The Coordination of n–hexane and n–heptane to Co((CH3)3Si)CNAR )3 ............ 108 vi 3.4 Topological Examination of Complexes (9·(n–C6H14)·2(C6H6)) and (10·(n–C7H16)) 112 3.5 Support for a σ–type Interaction from the Crabtree rbp Parameter ............................ 115 3.6 Van Der Waals interactions in complexes (9·(n–C6H14)·2(C6H6)) and (10·(n–C7H16) ............................................................................................................ 118 3.7 Computational Support at the DFT Level of Theory ................................................ 119 3.8 Computatinoal Support by the Atoms in Molecules Method .................................... 120 3.9 NMR Studies in Alkane Solvents .............................................................................. 122 3.10 Isolation of a Pseudo–Unsaturated XCoL3 Complex ................................................. 128 3.11 Single Crystal to Single Crystal Dinitrogen Intercalation Experiments .................... 131 Mes2 Mes 3.12 The Formation of a Flexible CNAr Pocket in Co(TMS)(Ar )3 ......................... 134 3.13 SC–SC Argon and Xenon Intercalation Experiments with Complex (12)................. 138 3.14 Polymorph Complex (20)........................................................................................... 142 3.15 Alkane Length vs. σ–complex stability in the Solid–State ........................................ 144 3.16 Conclusions ................................................................................................................ 146 3.17 Materials and Methods ............................................................................................... 147 3.18 Crystallographic Structure Determination ................................................................. 151 3.19 Pressure Cell Experiments ......................................................................................... 152 3.20 Argon Extrusion from a Bruker Kryoflex .................................................................. 152 3.21 General Computational Considerations ..................................................................... 152 3.22 Argon Extrusion from a Bruker Kryoflex .................................................................. 152 3.23 References .................................................................................................................. 194 vii LIST OF FIGURES Figure 1.1. Density Functional Theory molecular orbital diagrams highlighting the difference in bonding between ClIr(CO)(PH3)2 and HIr(CO)(PH3)2.. .............. 7 Figure 1.2. X–ray crystal structure of a neopentyl phosphine iridium(III) complex.. ....... 10 1 mAd Figure 1.3. Tri–alkyl phosphine P(CH2 Ad)(i-Pr)2 (L ; mAd = methylene-1- adamantyl).. ..................................................................................................... 11 1 mAd Figure 1.4. 500 MHz H NMR spectrum of L in C6D6 (20 ˚C).. .................................. 12 1 Figure 1.5. X–ray Crystal structure of P(CH2 Ad)(i-Pr)2. Hydrogens removed for clarity. Thermal ellipsoids are set to 30% probability.. ................................... 12 Figure 1.6. X–ray crystal structure of complex (1) Ir(COD)(Cl)(LmAd). Thermal ellipsoids set to 30% probability and hydrogen atoms were removed for