Reactivity of platinum-oxygen bonds: Kinetic and mechanistic studies of the carbonylation of platinum aryloxide complexes and the formation of (aryloxy)carbonyls
- Purdue Univ., West Lafayette, IN (United States)
The reactions of [Pt(triphos)(Cl)][Cl] (1) [C@triphos = bis[2-(diphenylphosphino)ethyl]phenylphosphine] with NaOC{sub 6}H{sub 4}-p-R, in the presence of NaPF{sub 6}, yields the aryloxy complexes [Pt(triphos)(OC{sub 6}H{sub 4}-p-R)][PF{sub 6}] (R = OMe (2a), Me (2b), H (2c), F (2d), Cl (2e)). Upon reaction of 2a-e with carbon monoxide at pressures from 10 to 134 psi in acetonitrile the (aryloxy)carbonyl complexes [Pt(triphos)(C(O)OC{sub 6}H{sub 4}-p-R)][PF{sub 6}] (3a-e) were obtained. The molecular structure of [Pt(triphos)(C(O)OC{sub 6}H{sub 4}-p-Me)][PF{sub 6}] (3b) was determined by X-ray diffraction. Complex 3b crystallized in the monoclinic space group P2{sub 1}n (no. 14). The kinetics of the carbonylation of 2a-e to form 3a-e were studied by {sub 31}P[C{sub 1}H] NMR. Rates of carbonylation exhibit a first order dependence on [CO], but are independent of the concentration of free aryloxide in solution. Rates of aryloxide ligand exchange were also found to be significantly faster than rates of carbonylation. The rates of carbonylation depend on the para-substituent of the aryloxy ligand and follow the order F(2d) > Me (2b) > OMe (2a). These observations are interpreted in terms of a carbonylation mechanism that proceeds via a migratory insertion pathway, rather than by nucleophilic attack at coordinated carbon monoxide by free or dissociated aryloxide. 54 refs., 5 figs., 5 tabs.
- DOE Contract Number:
- FG22-93PC93208
- OSTI ID:
- 263126
- Journal Information:
- Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 20 Vol. 118; ISSN JACSAT; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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