Synthesis and structural characterization of 1,8-biscobaltocen-1′-ylium-naphthalene dication: Towards paramagnetic, cofacially stacked metallocenes

The double nucleophilic addition of 1,8-dilithionaphthalene to cobaltocenium cations reveals the neutral dinuclear complex 1,8-bis[(η5-cyclopentadienyl)(η4-1′,3′-cyclopentadien-5′-yl)cobalt(I)]-naphthalene (2). Abstraction of two hydrides yields the dinuclear dicationic complex 1,8-biscobaltocen-1′-ylium-naphthalene bis(tetrafluoroborate) (3(BF4)2(BF4)2). Both complexes are characterized by X-ray structure analysis. In addition, the redox chemistry of 3(BF4)2 was investigated, demonstrating the electrochemical stability of three oxidation states +2, +1 and 0.

The crystal structure of 1,8-biscobaltocen-1′-ylium-naphthalene bis(tetrafluoroborate) (3(BF4)2BF4)2) displays the face-to-face arrangement of the two cobaltocenium cations. Cyclic voltammetry demonstrates two not completely separated redox couples with potentials in the range of the cobaltocenium cation.Figure optionsDownload as PowerPoint slide