Synthesis, structure and characterization of mixed cyclopentadienyl-dithiolene metal complexes, [Co(eta-C5H5)(2)][Ni(C3S5)(2)](3)center dot 2MeCN and [Ni(eta-C5H5)(C3S5)]

Two new compounds [Co(eta-C5H2)(2)][Ni(C3S5)(2)](3) . 2MeCN and [Ni(eta-C5H5)(C3S5)], both obtained by combination of the nickel complex anion [Ni(C3S5)(2)](-) (C3S5 = 4,5-disutfanyl-1,3-dithiole-2-thionate) and the metallocenium cation [M(eta-C5H2)(2)](+) (M = Co or Ni), respectively, have been prepared and characterized crystallographically. The non-integral oxidation-state cobalt complex with the unusual 1:3 stoichiometry was obtained by electrochemical oxidation of [NBu(4)][Ni(C3S5)(2)] in the presence of [Co(eta-C5H5)(2)]PF6. It is semiconductive (sigma = 0.06 S cm(-1) at room temperature, E(a) = 0.18 eV between 300 and 250 K). The crystal structure shows that the asymmetric unit contains one Ni(C3S5)(2) unit, one Ni(C3S5) entity, one Co(eta-C5H5) unit and one molecule of acetonitrile. The Ni(C3S5)(2) units are associated in triads stacked along the [101] direction. No significant differences are observed in the distances and angles within the two symmetry-unrelated Ni(C3S5)(2) units, indicating that the charges of both units are very similar. The cyclopentadienyl rings are staggered due to the location of the Co atoms on inversion centres. The average Co-C distance is comparable to those found in several cobaltocenium salts. The compound [Ni(eta-C5H5)(C3S5)] was obtained unexpectedly from the reaction of [Ni(eta-C5H5)(2)]BF4 with Na[Ni(C3S5)(2)] and characterized by mass spectrometry, conductimetry and X-ray analysis. The crystal structure shows that the asymmetric unit consists of one [Ni(eta-C5H5)(C3S5)] entity. The C5H5 ring is disordered over two positions. The Ni(C3S5) unit is planar and almost perpendicular to the C5H5 rings.