Synthesis and reactivity of bis(η-1,4-di-tert-butylbuta-1,3-diene)cobalt; the X-ray crystal structure of the anionic butadiene sandwich complex [K(18-crown-6)(thf)2][Co(η-C4H4But2)2]

Abstract

Cocondensation of cobalt atoms with 1,4-di-tert-butylbuta-1,3-diene affords the stable, paramagnetic butadiene sandwich compound [Co(η-C₄H₄Bu^t2)₂], which is a reactive source of Co⁰ fragments; reduction of [Co(η-C₄H₄Bu^t2)₂] with potassium affords the first crystallographically characterised homoleptic butadiene sandwich complex, [Co(η-C₄H₄Bu^t2)₂]^–, in which the bonding is that of a genuine diene rather than a metallacyclopentene.