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Carbonylation of hydrocarbylpalladium(II) complexes containing substituted pyridinecarboxylate chelating ligands. Steric and electronic manipulation of the CO-insertion mechanism

Citation

Hoare, JL and Cavell, KJ and Hecker, R and Skelton, BW and White, AH, Carbonylation of hydrocarbylpalladium(II) complexes containing substituted pyridinecarboxylate chelating ligands. Steric and electronic manipulation of the CO-insertion mechanism, Journal of the Chemical Society, Dalton Transactions, (11) pp. 2197-2205. ISSN 0300-9246 (1996) [Refereed Article]

DOI: doi:10.1039/dt9960002197

Abstract

Organopalladium(II) complexes of general formula [PdR(N-O)L] [R = Ph, N-O = pyridinecarboxylate (pyca), L = P(C 6 H 11 ) 3 ; R = Ph, N-O = 6-methylpyridinecarboxylate (mpyca), L = PPh 3 , PMePh 2 , P(C 6 H 11 ) 3 or PEt 3 ; R = Ph, N-O = 4-nitropyridinecarboxylate (npyca), L = P(C 6 H 11 ) 3 ; R = Ph, N-O = 6-methyl-4-nitropyridinecarboxylate, L = P(C 6 H 11 ) 3 ; R = Me, N-O = mpyca, L = PPh 3 , P(CH 2 Ph) 3 or P(C 6 H 11 ) 3 ; R = Me, N-O = npyca, L = PPh 3 , PMePh 2 or P(C 6 H 11 ) 3 ] have been prepared, and their carbonylation reactions studied in detail. Kinetic studies of the CO-insertion process have indicated that the rate of reaction decreases as the basicity of the phosphine, L, increases. Complexes containing the highly basic phosphine P(C 6 H 11 ) 3 only undergo carbonylation if hemilability of the chelating ligand is promoted (by substitution of the N-O chelate). Substitution of the N-O ligand modifies the carbonylation pathway and provides an alternative route from that generally observed for palladium(II) and platinum(II) hydrocarbyl complexes of pyca. A mechanism for insertion of CO involving partial dissociation of the N-O chelate is proposed for these complexes. The crystal stucture of [PdMe(mpyca)(PPh 3 )] has been determined. The complex has square-planar co-ordination with the nitrogen of pyca trans to the phosphorus. Considerable distortion of the inner co-ordination sphere is evident, caused by steric interactions betwen the σ-methyl ligand and the methyl group on the N-O ligand.

Item Details

Item Type:Refereed Article
Research Division:Chemical Sciences
Research Group:Inorganic Chemistry
Research Field:Transition Metal Chemistry
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Chemical Sciences
Author:Hoare, JL (Mr Jason Lancelot Hoare)
Author:Cavell, KJ (Professor Kingsley Cavell)
ID Code:8408
Year Published:1996
Web of Science® Times Cited:42
Deposited By:Chemistry
Deposited On:1996-08-01
Last Modified:2011-08-19
Downloads:0

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