The first systematic synthesis of heterobimetallic dithiolene-bridged complexes.: Synthesis and characterization of metal complexes of 4-(1′,2′-ethylenedithiolate)-1,3-dithiole-2-one and dimeric metal complexes of 1,2,3,4-butadienetetrathiolate

The 1,2-dithiolene ligands 4-(1',2'-ethylenedithiolate)-1,3-dithiole-2-one (eddo(2-)) and 1,2,3,4-butadienetetrathiolate (bdt(4-)) are synthesized by the controlled single or double 1,3-dithiole-2-one ring opening of 4,4'-bis(1,3-dithiole-2-one) (bdo) (1). The synthesis and characterization of the novel transition metal complexes (COD)Pt(eddo) (2), (diphos)Ni(eddo) (3), [Bu4N][Ni(eddo)(2)] (4), (COD)Pt(bdt)Pt(COD) (5), and (diphos)Ni(bdt)Pt(COD) (6) (where COD = 1,5-cyclooctadiene, diphos = 1,2-bis(diphenylphosphino)ethane) are reported. Use of eddo(2-) and bdt(4-) results in the selective systematic synthesis of transition metal monomers and dimers. In addition, the synthesis of mixed metal dimeric complexes utilizing a "transition metal 1,2-dithiolene" ligand is demonstrated. The single-crystal X-ray structural analyses of the cocrystallized (COD)Pt(eddo).1/2 bdo, monoclinic, P2(1)/n, a = 13.0388(4) Angstrom, b = 9.2038(3) Angstrom, c = 16.2384(5) Angstrom, beta = 97.289(5)degrees, Z = 4, and [Bu4N][Ni(eddo)(2)], monoclinic, P2(1)/n, a = 8.3508(2) Angstrom, b = 26.4703(7), c = 15.2778(3) Angstrom, beta = 99.8160(10)degrees, Z = 4, are reported. There is strong evidence of delocalization through the butadiene backbone of 1 which extends into the sulfur atoms. It also appears that there is some delocalization through the butadiene backbone of the eddo(2-) ligands in 2 and 4.