Organopalladium complexes with bidentate phosphorus and nitrogen containing ligands

Article abstract of DOI:10.1016/0022-328X(88)87102-X

Organopalladium complexes containig the potentially P,N-bidentate ligands o-diphenylphosphino-N,N-dimethylbenzylamine (PN) and o-diphenylphosphino-α-methyl-N,N-dimethylbenzylamine (PN^*) have been studied.The palladium(0) complexes Pd(P-N)3 (P-N=PN or PN^*) have been prepared; the ligands coordinate to the metal primarily through phosphorus, with the amine function coordinating not at all or only weakly.Oxidative addition of several organic halides to these palladium(0) complexes afforded the corresponding monoorganopalladium(II) complexes Pd(R)(X)(P-N) in which the donor ligands are P,N bidentate coordinated.In solution the divalent species possess a Pd-N bond, and even in the presence of either free ligand, CO or X^- there is no evidence for dissociation or displacement of the amine function from the metal centre.Complexes PdMe2(P-N) have been prepared from the corresponding dihalopalladium complexes by treatment with MeLi.Reaction of these dimethylpalladium species with electrophiles MeI, MeBr and PhCH2Br resulted in replacement of one methyl group by halogen.The structures of Pd(Me)(Br)(PN) and Pd(CCSiMe3)(Br)(PN) have been determined by X-ray diiraction studies.Pd(Me)(Br)(PN) crystallizes in space group Cc with a 8.379(8), b 17.363(7) and c 14.818(6) Angstroem, β 99.34(5) deg, and Z = 4; the structure was refined to R_f = 0.030.Pd(CCSiMe3)(Br)(PN) crystallizes in space group P2₁/c with a 13.478(3), b 10.848(2) and c 19.212(3) Angstroem, β 102.59(2), and Z = 4; the structure was refined to R_f = 0.038.Both complexes have a square planar configuration around palladium, with the organic group (Me, CCSiMe3) trans to the amine function and the six-membered chelate ring in boat conformation.