Easy access to uranium nucleophilic carbene complexes.

Metathesis reactions of UCl(4) with Li(2)C(Ph(2)PS)(2) in Et(2)O only afforded the tris-carbene complex [{Li(OEt(2))}(2)U{=C(Ph(2)PS)(2)}(3)] (1), while the bis- and mono-carbene compounds [U{=C(Ph(2)PS)(2)}(2)(THF)(2)] (2) and [{Li(THF)(2)}(2)U{=C(Ph(2)PS)(2)}Cl(4)] (3) were obtained by treatment of UCl(4) with Li(2)C(Ph(2)PS)(2) in a mixture of THF and toluene. The bis-carbene complex 2 was also obtained either from the comproportionation reaction of 1 and UCl(4) or protonolysis reaction of U(NEt(2))(4) with H(2)C(Ph(2)PS)(2) and was transformed into the mono-carbene complex [U{=C(Ph(2)PS)(2)}Cl(2)(THF)(2)] (4) by further reaction with UCl(4). The utility of these complexes as precursors is illustrated by the synthesis of the biscyclopentadienyl derivative [Cp(2)U{=C(Ph(2)PS)(2)}] (5) by treatment of 3 with TlCp. The crystal structures of [U{=C(Ph(2)PS)(2)}(2)(py)(2)].1.5py.0.5THF and 5.toluene are reported.