Camphor-derived β-ketophosphine complexes of palladium( II ) and platinum( II )

Reaction of chlorodiphenylphosphine with the lithium enolate derived from the treatment of (1R)-endo-(+)-3-bromocamphor (camphor = bornan-2-one) with n-butyl-lithium gives (1R)-endo-(+)-3-diphenylphosphinocamphor (L). This new chiral β-ketophosphine ligand reacts with [Pd(CH3CN)2Cl2] to give trans-[PdL2Cl2], and in a 1 : 1 ratio to give the chloro-bridged dimer [{PdL(µ-Cl)Cl}2]. The ligand L reacts with [Pt(CH3CN)2Cl2] to give trans-[PtL2Cl2]. Thermolysis of [ML2Cl2](M = Pd or Pt) in refluxing xylene gives mixed phosphine–phosphinite complexes with mutually cis chlorides. The complex [PdL2Cl2] reacts with an excess of AgBF4 to give [PdL2][BF4]2 which is shown to contain bidentate binding through the phosphorus and keto-oxygen atoms. All complexes are characterised by i.r., 1H and 31P n.m.r. spectroscopy.