Organic reactions involving transition metals. Part VI. Complexes of unsaturated tertiary phosphines with palladium(II) and platinum(II), and their reactions with nucleophiles

Abstract

Palladium(II) and platinum(II) complexes of the ligands CH₂:CH·[CH₂]_n·PPh₂(n= 1,2,3) have been investigated. The but-3-enylphosphine chelates to palladium or platinum, the pent-4-enylphosphine chelates only to platinum, and the allylphosphine chelates to neither metal. The but-3-enyl complexes of platinum react with methoxide or acetate ion, and the pent-4-enyl complexes react with methoxide ion, to give predominant addition of the nucleophile to the β-carbon atom, [[graphic omitted]tX]₂(n= 2,3, X = Cl, R = Me; n= 2, X = CO₂Me, R = Ac). Carboxylate ions (CH₂Y·CO₂^–, Y = H, Cl, F) displace the co-ordinate double bond of the pent-4-enyl complex from the metal to give the carboxylate-bridged dimers {CH₂:CH·[CH₂]₃PPh₂Pt(O₂C·CH₂Y)₂}₂. The complexes are characterised by bridge-splitting reactions and by i.r. and n.m.r. spectroscopy.