"Homo- And Heteronuclear Clusters Of Platinum And Gold" by Ravindranath Ramachandran

Date of Award

1990

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Abstract

This thesis documents the chemistry of some homo- and heteronuclear cluster complexes of gold and platinum.;The reaction of (AuC{dollar}\equiv{dollar}C{dollar}t{dollar}-Bu) with the diphosphine ligands, CH{dollar}\sb2{dollar}(PR{dollar}\sb2{dollar}){dollar}\sb2{dollar} (R = Me, dmpm; R = Ph, dppm; R = {dollar}-{dollar}OMe, dmopm), yielded a number of complexes. Complexes ({dollar}t{dollar}-BuC{dollar}\equiv{dollar}C-Au-R{dollar}\sb2{dollar}PCH{dollar}\sb2{dollar}OR{dollar}\sb2{dollar}) (R = Me, Ph) were fluxional in solution. The crystal structures of (Au{dollar}\sb2{dollar}({dollar}\mu{dollar}-dmpm){dollar}\sb2{dollar}) X{dollar}\sb2\cdot{dollar}2H{dollar}\sb2{dollar}O (X = C{dollar}\ell{dollar}, I) were determined, as was that of (Au{dollar}\sb2{dollar}(C{dollar}\equiv{dollar}C{dollar}t{dollar}-Bu){dollar}\sb2{dollar}({dollar}\mu{dollar}-dppm)). Complex (CH{dollar}\sb2\{lcub}{dollar}P(MeO){dollar}\sb2{dollar}Au(C{dollar}\equiv{dollar}C{dollar}t{dollar}-Bu){dollar}\{rcub}\sb2{dollar}) oligomerized in chlorinated solvents to give (Au{dollar}\sb2{dollar}(C{dollar}\equiv{dollar}C{dollar}t{dollar}-Bu){dollar}\{lcub}\mu\sb3- {dollar}(MeO){dollar}\sb2{dollar}PCHP(OMe){dollar}\sb2\{rcub}{dollar}) {dollar}\sb3{dollar}, and then (Au{dollar}\sb8{dollar}C{dollar}\ell\sb2\{lcub}\mu\sb3- {dollar}(MeO){dollar}\sb2{dollar}PCHP(OMe){dollar}\sb2\{rcub}\sb2\{lcub}\mu\sb4- {dollar}(MeO){dollar}\sb2{dollar}PCP(OMe){dollar}\sb2\{rcub}\sb2{dollar}) {dollar}\cdot{dollar}CHC{dollar}\ell\sb3{dollar}. The structure of the octagold cage was determined by X-ray crystallography, and was shown to contain the first structurally characterized example of ({dollar}\mu\sb4- {dollar}R{dollar}\sb2{dollar}PCPR{dollar}\sb2{dollar}) {dollar}\sp{lcub}2-{rcub}{dollar} ligand. A reaction pathway to form the octagold complex is postulated.;The chemistry of homo- and heteronuclear complexes of platinum discussed are based on the triplatinum cluster, (Pt{dollar}\sb3{dollar}({dollar}\mu\sb3-{dollar}H)({dollar}\mu-{dollar}dppm){dollar}\sb3{dollar}) {dollar}\sp+{dollar}, 1. Auration of complex 1 with AuPPh{dollar}\sb3\sp+{dollar} gave (Pt{dollar}\sb3{dollar}({dollar}\mu\sb3-{dollar}H)({dollar}\mu\sb3-{dollar}AuPPh{dollar}\sb3{dollar})({dollar}\mu-{dollar}dppm){dollar}\sb3{dollar}) (PF{dollar}\sb6{dollar}){dollar}\sb2{dollar}, which can be deprotonated to (Pt{dollar}\sb3{dollar}({dollar}\mu\sb3-{dollar}AuPPh{dollar}\sb3{dollar})({dollar}\mu-{dollar}dppm){dollar}\sb3{dollar}) (PF{dollar}\sb6{dollar}) and then further aurated to (Pt{dollar}\sb3{dollar}({dollar}\mu\sb3-{dollar}AuPPh{dollar}\sb3{dollar}){dollar}\sb2{dollar}({dollar}\mu-{dollar}dppm){dollar}\sb3{dollar}) (PF{dollar}\sb6{dollar}){dollar}\sb2{dollar}. The reactions of these hetero bimetallic complexes with various main group reagents were also studied.;The reaction of tertiary phosphines and phosphites, L, with 1 yielded the clusters (Pt{dollar}\sb3{dollar}({dollar}\mu\sb3-{dollar}H)(L)({dollar}\mu-{dollar}dppm){dollar}\sb3{dollar}) (PF{dollar}\sb6{dollar}). The cluster complex (Pt{dollar}\sb3{dollar}({dollar}\mu\sb3-{dollar}H){dollar}\{lcub}{dollar}P(OMe){dollar}\sb3\{rcub}{dollar}({dollar}\mu-{dollar}dppm){dollar}\sb3{dollar}) (PF{dollar}\sb6{dollar}) was characterized by X-ray crystallography. These clusters contain an asymmetrically capping hydride ligand for which the spectroscopic parameters were obtained. The phosphine and phosphite ligands displayed a unique fluxionality which was deduced using multinuclear NMR data.;The triplatinum complex 1 can be protonated rapidly and reversibly by aq. HPF{dollar}\sb6{dollar}, to give (Pt{dollar}\sb3{dollar}({dollar}\mu\sb3-{dollar}H){dollar}\sb2{dollar}({dollar}\mu-{dollar}dppm){dollar}\sb3{dollar}) {dollar}\sp{lcub}2+{rcub}{dollar}, and (Pt{dollar}\sb3{dollar}({dollar}\mu\sb3-{dollar}H){dollar}\sb3{dollar}({dollar}\mu-{dollar}dppm){dollar}\sb3{dollar}) {dollar}\sp{lcub}3+{rcub}{dollar}. Use of CF{dollar}\sb3{dollar}COOH yielded an asymmetric complex, (Pt{dollar}\sb3{dollar}({dollar}\mu\sb3-{dollar}H)(H)({dollar}\mu-{dollar}dppm){dollar}\sb3{dollar}({dollar}\mu-{dollar}CF{dollar}\sb3{dollar}COO)) {dollar}\sp+{dollar}. These dihydrido complexes react with CO to quantitatively eliminate hydrogen and form (Pt{dollar}\sb3{dollar}({dollar}\mu\sb3-{dollar}CO)({dollar}\mu-{dollar}dppm){dollar}\sb3{dollar}) {dollar}\sp{lcub}2+{rcub}{dollar}, 2. They also react with various phosphine and phosphite ligands, L, to yield (Pt{dollar}\sb3{dollar}({dollar}\mu-{dollar}H)(H)(L)({dollar}\mu-{dollar}dppm){dollar}\sb3{dollar}) {dollar}\sp{lcub}2+{rcub}{dollar}. Phenyl phosphine, PPhH{dollar}\sb2{dollar}, reacted with 1 to yield (Pt{dollar}\sb3{dollar}({dollar}\mu\sb3-{dollar}PPh)(H)({dollar}\mu-{dollar}dppm){dollar}\sb3{dollar}) {dollar}\sp+{dollar}.;The chemistry of some tetraplatinum clusters was examined. The reaction of complexes 1 and 2 with the Pt(0) reagent, (Pt(CO){dollar}\sb2{dollar}(PPh{dollar}\sb3{dollar}){dollar}\sb2{dollar}), yielded (Pt{dollar}\sb4{dollar}({dollar}\mu- {dollar}H)({dollar}\mu- {dollar}CO){dollar}\sb2{dollar}(PPh{dollar}\sb3{dollar})({dollar}\mu- {dollar}dppm){dollar}\sb3{dollar}) {dollar}\sp+{dollar}, and (Pt{dollar}\sb4{dollar}({dollar}\mu- {dollar}CO){dollar}\sb2{dollar}(PPh{dollar}\sb3{dollar})({dollar}\mu- {dollar}dppm){dollar}\sb3{dollar}) {dollar}\sp{lcub}2+{rcub}{dollar}, respectively. The fluxionality of these clusters was deduced on the basis of variable temperature NMR data and by comparison with the previously characterized cluster (Pt{dollar}\sb4{dollar}({dollar}\mu- {dollar}H)({dollar}\mu- {dollar}CO){dollar}\sb2{dollar}({dollar}\mu- {dollar}dppm){dollar}\sb3{dollar}({dollar}\eta\sp1- {dollar}dppm)) {dollar}\sp+{dollar}.

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