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

Abstract

Treatment of a solution of [U^IV(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 [U^IV(cp)₃(NCMe)₂]⁺, the anion [U^VIO₂Cl₄]^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 U^V and U^VI with the cp ligand.