Intermolecular exchanges of tertiary phosphine ligands (L) between trans-[NiRXL2](R = CClCCl2, C6Cl5, or C6H2Me3-2,4,6) and of halide ligands (X) between trans-[MRXL2](M = Ni, Pd, or Pt)

Abstract

The intermolecular exchanges of tertiary phosphine ligands (L, L′) occur between trans-[NiRXL₂] and trans-[NiRXL′₂](R = CClCCl₂, C₆Cl₅, or C₆H₂Me₃-2,4,6; X = halide, pseudohalide, or CCR′) in benzene to give a mixture containing trans-[NiRXLL′], as detected from the ¹H and/or ³¹P-{¹H} n.m.r. spectra. The reactivity appears to depend largely on the nature of the ligands R and X, but the equilibrium constants are in the narrow range 4–9. The intermolecular exchanges of halide ligands between trans-[NiRXL₂] and trans-[NiR′X′L₂](X, X′= Cl, I, N₃, or NCS) are usually fast at room temperature. The relative affinities of [NiRL₂] moieties towards these halide ligands are almost independent of the nature of the ligands R and L (K= 0.3—3.0). The Pd and Pt moieties trans-[M(C₆Cl₅)(PMe₂Ph)₂] were comparable in the relative affinities towards X (Cl and I) ligands, although they are in favour of the M–I bond formation relative to the Ni moieties.