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

Abstract

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.