Formation and crystal structure of trans-bis(acetonitrile)tris(η⁵-cyclopentadienyl)uranium(<scp>IV</scp>) tetrachloro-trans-dioxouranate(<scp>VI</scp>) : a novel species involving the first cationic organo-f-metal complex and uranium in two different oxidation states

Abstract

Treatment of a solution of [UIV(cp)3Cl](cp =η5-C5H5) in CH3CN with gaseous butadiene containing traces of O2 initiates the formation of a crystalline green product composed of the novel cationic complex [UIV(cp)3(NCMe)2]+, the anion [UVIO2Cl4]2–, and two non-co-ordinated butadiene molecules. This salt contains the first example of a well defined cationic organo-f-element complex, and provides at the same time a new example of a crystallographically confirmed [U(cp)3XY](X, Y = neutral and/or anionic ligand) system of trigonal bipyramidal co-ordination. The results are discussed in relation to the as yet unsubstantiated access to organometallic compounds of UV and UVI with the cp ligand.