Date of Award
1989
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Abstract
This thesis examines the reactivity of the coordinatively unsaturated triplatinum cluster (Pt{dollar}\sb3(\mu\sb3{dollar}-CO){dollar}(\mu{dollar}-dppm){dollar}\sb3\rbrack{dollar} (PF{dollar}\sb6\rbrack \sb2{dollar}, 1. The complex can act as a model for a triangle of platinum atoms on a Pt(111) surface and this thesis describes studies of its reactivity towards various main group reagents.;The halide ions, Cl{dollar}\sp-{dollar}, Br{dollar}\sp-{dollar} and I{dollar}\sp-{dollar}, yielded the clusters (Pt{dollar}\rm\sb3(\mu\sb3{dollar}-CO){dollar}(\mu\sb3{dollar}-X)({dollar}\mu{dollar}-dppm){dollar}\sb3\rbrack \sp{lcub}1+{rcub}{dollar} which were characterized spectroscopically. Attempts were made to investigate the bonding in these systems with respect to the degree of ionic, or covalent, character in the Pt{dollar}\rm\sb3(\mu\sb3{dollar}-X) bonds through ligand exchange studies.;Monodentate tertiary phosphines and phosphites yielded the clusters (Pt{dollar}\rm\sb3(\mu{dollar}-CO)L{dollar}(\mu{dollar}-dppm){dollar}\sb3\rbrack\sp{lcub}2+{rcub}{dollar}, L = phosphine or phosphite. The cluster complex (Pt{dollar}\rm\sb3(\mu\sb3{dollar}-CO){dollar}\rm\{lcub}P(OPh)\sb3\{rcub}(\mu{dollar}-dppm){dollar}\sb3\rbrack \sp{lcub}2+{rcub}{dollar} was characterized by X-ray crystallography. The possibility of a Pt{dollar}\rm\sb3(\mu\sb3{dollar}-PF{dollar}\sb3){dollar} group, unique fluxionality of the phosphine and posphite ligands and asymmetrically capping CO ligands are interesting features of these clusters.;The novel cluster (Pt{dollar}\rm\sb3(\mu{dollar}-CO)({dollar}\mu{dollar}-dppm){dollar}\sb4\rbrack\sp{lcub}2+{rcub}{dollar} was synthesized and was particularly interesting because the {dollar}\mu{dollar}-dppm ligand beneath the plane of the platinum triangle displays a new form of fluxionality not previously observed from dppm.;The triplatinum cluster, complex 1, was reacted with various isocyanides to form the clusters (Pt{dollar}\rm\sb3(\mu\sb3{dollar}-CO)CNR{dollar}(\mu{dollar}-dppm){dollar}\sb3\rbrack\sp{lcub}2+{rcub}{dollar}. The mechanism of the reaction was followed by variable temperature NMR spectroscopy and a novel mechanism of ligand addition for metal-isocyanide complexes was observed.;The cluster (Pt{dollar}\sb3(2,6{dollar}-{dollar}\rm Me\sb2C\sb6H\sb3NC)\sb2)(\mu{dollar}-dppm){dollar}\sb3\rbrack\sp{lcub}2+{rcub}{dollar} was synthesized by adding two molar equivalents of 2,6-Me{dollar}\sb2{dollar}C{dollar}\sb6{dollar}H{dollar}\sb3{dollar}NC to (Pt{dollar}\rm\sb3(\mu\sb3{dollar}-CO){dollar}(\mu{dollar}-dppm){dollar}\sb3\rbrack \sp{lcub}2+{rcub}{dollar}. This complex was characterized by X-ray crystallography and is the first Pt{dollar}\sb3(\mu{dollar}-dppm){dollar}\sb3{dollar} cluster with no capping ligand. The structure also appears to violate the theoretical results obtained for similar systems suggesting that a new theoretical treatment may be warranted.;Mechanistic studies using variable temperature NMR were done on the reaction of various isothiocyanates with complex 1. The strong C=S bond of the isothiocyanate is cleaved under mild conditions by this Pt{dollar}\sb3{dollar} cluster.;Finally a tetraplatinum cluster was also examined. The fluxionality of this cluster, which differs from that of the usual tetraplatinum butterfly fluxionality, was proposed on the basis of variable temperature NMR data.
Recommended Citation
Bradford, Arleen Marie, "Coordination Chemistry Of A Coordinatively Unsaturated Trinuclear Platinum Cluster" (1989). Digitized Theses. 1828.
https://ir.lib.uwo.ca/digitizedtheses/1828