Synthesis, structure and NLO properties of a 1,3,5-substituted tricationic cobaltocenium benzene complex

Interested in the nonlinear optical properties of multinuclear metallocene-substituted complexes, we were successful in synthesizing the homotrinuclear coordination compound [1,3,5-tris(η5-2,4-cyclopentadien-1-yl)(η4-2,4-cyclopentadienyl-1-ethynyl)cobalt(I)]benzene (1) via a threefold nucleophilic addition to cobaltocenium cations. Upon hydride abstraction, the target compound [1,3,5-tris(η5-2,4-cyclopentadien-1-yl)(η5-2,4-cyclopentadienyl-1-ethynyl)-cobalt(III)]benzene tris(hexafluoridophosphate) (2) was obtained. Both complexes were fully characterized and, in continuation of previous investigations, investigated in terms of the influence of an octopolar arrangement of acceptor functions on the nonlinear optical activity of organometallic compounds.