The complete carbonylation mechanism for the model palladium(II) system, Pd(PH3)(CH3)-(N-O) + CO → Pd(PH3)(COCH3)(N-O) (N-O = NHCHCOO-), has been investigated employing nonlocal density functional theory (DFT) and second-order Mø11er-Plesset perturbation theory (MP2). Four possible mechanisms were identified, all involving the initial displacement of the phosphine ligand by carbon monoxide via a trigonal bipyramidal transition structure. Of these four mechanisms, the rate-determining methyl migration step was found to be lowest in energy when proceeding from a novel five-coordinate intermediate in which the palladium-nitrogen bond is weakened (2.385 Å at the MP2 level of theory). This mechanism is consistent with the available experimental data. MP2 calculations using large basis sets predicted an overall exothermicity of -59.7 kJ/mol and a negligible activation energy of +6.0 kJ/mol with respect to the separated reactants. In addition, a novel transition structure that accounts for the isomerization of square-pyramidal d8 complexes is presented.

Item Type:	Refereed Article
Research Division:	Chemical Sciences
Research Group:	Theoretical and computational chemistry
Research Field:	Theoretical and computational chemistry not elsewhere classified
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the chemical sciences
UTAS Author:	Frankcombe, KE (Ms Katrina Ellen Frankcombe)
UTAS Author:	Cavell, KJ (Professor Kingsley Cavell)
UTAS Author:	Yates, BF (Professor Brian Yates)
ID Code:	11939
Year Published:	1997
Web of Science® Times Cited:	26
Deposited By:	Chemistry
Deposited On:	1997-08-01
Last Modified:	2011-08-15
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