Methyl-, acetyl- and allyl-palladium and -platinum complexes containing the novel chiral phosphorus-imine 2-(diphenylphosphino)-benzylidene-S(-)-a-methyl-benzylamine ligand

Abstract

Neutral compounds of the type [MX2(L)] and [MX(Me)(L)] and ionic complexes of the type [M(Me)(L)](O3SCF3), in which X = Cl, Br, I; M = Pd, Pt; L = 2-(diphenylphosphino)-benzylidene-S- − )--methyl-benzylamine, have been prepared and characterized. Single crystal X-ray determinations of [PdCl2(L)] (1a) and [PtI2(L)] (3b) showed, in both cases, a chelate coordination of the PN ligand thereby forming a six-membered ring. The square planar surrounding is completed by the two halide atoms. The single crystal X-ray determination of [PdCl(Me)Cl(L)] (4a) shows an analogous geometry with a chelating PN ligand, a chloride atom and a methyl group, which is positioned cis to the phosphorus atom, completes the square planar surrounding. The methylpalladium and -platinum complexes reacted with CO to give the corresponding acetyl complexes. The insertion rates increased in the order Cl<Br<O3SCFP3− while the reaction is first order in metal complex and first order in CO concentration. Complexes [Pd(3-allyl)(PN)]+Y− (Y = Cl, O3SCF3) with symmetric allyl groups 2-RC3H5 (R = Me, C(O)Me), 2-MeC3Me4 and asymmetrically substituted allyl groups 2-R-C3H2Me2 (R = H, Me) have been prepared. Temperature dependent 1H, 31P{1H} and 13C{1H} NMR has been used to determine the influence of the chiral ligand on the structural aspects and dynamic features. It is shown that a delicate balance between counteracting steric and electronic factors determines the type of isomer, i.e. with the P atom cis or trans to the CMe2 moiety of the asymmetric allyl group.