Studies on hydrogen bonding in transition metal chemistry

This thesis deals with conventional and unconventional types of hydrogen bonding in inorganic chemistry, specifically with groups 7 (rhenium) and 9 (iridium) transition metal hydride complexes.; In Chapter 2 we discuss the solid state characterization of intramolecular and intermolecular N-H{dollar}sp{lcub}delta+{rcub}cdotssp{lcub}delta-{rcub}{dollar}H-Re proton-hydride interactions in crystalline (ReH{dollar}sb5{dollar}(PPh{dollar}sb3)sb2{dollar}(NH{dollar}rmsb2CHsb3{dollar})), and {dollar}rm{lcub}lbrack ReHsb5(PPhsb3)sb2(imidazole)rbrack.0.5imidazole.1.5Csb6Hsb6{rcub}{dollar}. These proton-hydride interactions are believed to be unconventional hydrogen bonds, in which a negatively polarized hydride ligand serves as the proton acceptor. Alternatively, in the solid state they can be viewed as arrested proton transfers, and therefore have direct implications for hydrogen atom transfer mechanisms involving metal hydride ligands.; In Chapter 3 we discuss the first reported application of a proton-hydride interaction, in which the barrier for hydride exchange in {dollar}rmlbrack ReHsb5(PPhsb3)sb2(2{dollar}-NH(Ac)-pyridine)) is lowered, relative to {dollar}rmlbrack ReHsb5(PPhsb3)sb2({dollar}4-NH(Ac)-pyridine)) and {dollar}rmlbrack ReHsb5(PPhsb3)sb2(pyridine)rbrack{dollar}, as a result of intramolecular N-H{dollar}sp{lcub}delta+{rcub}cdotssp{lcub}delta-{rcub}{dollar}H-Re stabilization in the fluxional transition state.; Chapters 4-6 examine the incorporation of a conventional hydrogen bonding group into the ligand sphere of a known organometallic complex, to control structure and reactivity in a series of octahedral iridium (III) complexes based on the new ligand 2-amino-7,8-benzoquinoline (2-NH{dollar}sb2{dollar}-bzq).; Chapter 4 reports the synthesis of the new ligand 2-NH{dollar}sb2{dollar}-bzq, and the corresponding aqua complex (Ir(2-NH{dollar}sb2{dollar}-bzq)(PPh{dollar}sb3)sb2{dollar}(H)(H{dollar}sb2{dollar}O)) (BF{dollar}sb4{dollar}). We show how the juxtaposition of the bzq amino group leads to an intramolecular Ir-O-H{dollar}sbcdots{dollar}N hydrogen bond between the aqua ligand and the amino nitrogen.; In Chapter 5 we discuss the intramolecular hydrogen bond in (Ir(2-NH{dollar}sb2{dollar}-bzq)(PPh{dollar}sb3)sb2{dollar}(H)(F)), and show spectroscopic evidence which suggests that low temperature protonation of this fluoro complex leads to a hydrogen fluoride ligand in the complex (Ir(2-NH{dollar}sb2{dollar}-bzq)(PPh{dollar}sb3)sb2{dollar}(H)(FH)) (BF{dollar}sb4{dollar}). We discuss evidence which suggests that the labile HF ligand in this complex remains bound to the metal center because of an intramolecular Ir-F-H{dollar}sbcdots{dollar}N hydrogen bond.; Chapter 6 reports the activation of dihydrogen in (Ir(2-NH{dollar}sb3{dollar}-bzq)(PPh{dollar}sb3)sb2{dollar}(H){dollar}sb2{dollar}) (BF{dollar}sb4{dollar}), and the fluxional nature of the hydride ligands, as a result of intramolecular proton transfer within the complex.