BINUCLEAR COMPLEXES OF 1,4-DIAZA-3-METHYLBUTADIEN-2-YL-PALLADIUM(II) DERIVATIVES WITH PALLADIUM(II) AND PLATINUM(II) CHLORIDES

The organometallic 1,4-diazabutadienes, RN=C(R′)C(Me)=NR [R = p-C6H4OMe, R′ = trans-PdCl(PPh3)2 (DAB); PdCl(LL), LL = 1,2-bis(diphenylphosphino)-ethane (DABI), LL = cis-1,2-bis(diphenylphosphino)ethylene (DABII); Pd(dmtc)-(PPh3), dmtc = dimethyldithiocarbamate (DABIII)] react with ethylene or nitrile derivatives of palladium(II) and platinum(II), [PdCl2(CH2 = CH2)]2, K[PtCl3-(CH2=CH2)], [PdCl2(NCMe)2], [PtCl2(NCPh)2] usually to give binuclear complexes of the type [MCl2{RN = C(R′)C(Me)=NR}] (M = Pd, Pt), in which the 1,4-diazabutadiene group acts as a chelating bidentate ligand. The stability of these compounds in hot 1,2-dichloroethane or acetonitrile markedly depends on the nature of the ancillary ligands on the palladium atom of the group R′. When a chelating diphosphine is present, as in the case of DABI and DABII, the corresponding binuclear complexes are recovered unchanged even after long refluxing times. In the case of DAB and DABIII adducts, a transfer of PPh3 and dmtc ligands from the Pd atom of R′ to the metal atom M of the coordinated MCl2 unit occurs with the formation of trans-MCl2(PPh3)2] and of the new bimetallic complexes, [M(dmtc) {RN=C(R″)C(Me)=NR}] (R″ = cis-PdCl2(PPh3) (DABIV)), respectively. The rates of ligand transfer for the PdCl2 adducts are much higher than for the PtCl2 analogues. © 1979.