Organopalladium complexes with bidentate phosphorus and nitrogen containing ligands.
Organopalladium complexes contg. the potentially P,N-bidentate ligands o-diphenylphosphino-N,N-dimethylbenzylamine (PN) and o-diphenylphosphino-a-methyl-N,N-dimethylbenzylamine (PN*) have been studied. The palladium(0) complexes Pd(P-N)3 (P-N = PN, PN*) have been prepd.; the ligands coordinate to the metal primarily through P, with the amino function coordinating not at all or only very weakly. Oxidative addn. of several org. halides (RX = MeI, MeBr, Me3SiC.tplbond.CBr) 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 soln. 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 dissocn. or displacement of the amine function from the metal center. Complexes PdMe2(P-N) have been prepd. from the corresponding dihalopalladium complexes by treatment with MeLi. Reaction of these dimethylpalladium species with the electrophiles MeI, MeBr and PhCH2Br resulted in replacement of one Me group by halogen. The structures of Pd(Me)(Br)(PN) and Pd(C.tplbond.CSiMe3)(Br)(PN) have been detd. by x-ray diffraction studies. Both complexes have a square planar configuration around palladium with the org. group (Me, C.tplbond.CSiMe3) trans to the amine function and the six-membered chelate ring in a boat conformation.
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