Synthesis, structure and characterization of mixed cyclopentadienyl–dithiolene metal complexes, [Co(η-C5H5)2][Ni(C3S5)2]3·2MeCN and [Ni(η-C5H5)(C3S5)]

Abstract

Two new compounds [Co(η-C₅H₅)₂][Ni(C₃S₅)₂]₃·2MeCN and [Ni(η-C₅H₅)(C₃S₅)], both obtained by combination of the nickel complex anion [Ni(C₃S₅)₂]^–(C₃S₅= 4,5-disulfanyl-1,3-dithiole-2-thionate) and the metallocenium cation [M(η-C₅H₅)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 [NBu₄][Ni(C₃S₅)₂] in the presence of [Co(η-C₅H₅)₂]PF₆. It is semiconductive (σ= 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 (η-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(η-C₅H₅)(C₃S₅)] was obtained unexpectedly from the reaction of [Ni(η-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(η-C₅H₅)(C₃S₅)] entity. The C₅H₅ ring is disordered over two positions. The Ni(C₃S₅) unit is planar and almost perpendicular to the C₅H₅ rings.