Easy access to uranium nucleophilic carbene complexes

Metathesis reactions of UCl4 with Li2C(Ph2PS)(2) in Et2O only afforded the tris-carbene complex [{Li(OEt2)}(2)-U{=C(Ph2PS)(2)}(3)](1), while the bis- and mono-carbene compounds [U{=C(Ph2PS)(2)}(2)(THF)(2)] (2) and [{Li(THF)(2)}(2)U{=C(Ph2PS)(2)}Cl-4] (3) were obtained by treatment of UCl4 with Li2C(Ph2PS)(2) in a mixture of THF and toluene. The bis- carbene complex 2 was also obtained either from the comproportionation reaction of 1 and UCl4 or protonolysis reaction of U(NEt2)(4) with H2C(Ph2PS)(2) and was transformed into the mono- carbene complex [U{=C(Ph2PS)(2)}Cl-2(THF)(2)] (4) by further reaction with UCl4. The utility of these complexes as precursors is illustrated by the synthesis of the biscyclopentadienyl derivative [Cp2U{=C(Ph2PS)(2)}] (5) by treatment of 3 with TlCp. The crystal structures of [U{=C(Ph2PS)(2)}(2)(py)(2)]center dot 1.5py center dot 0.5THF and 5 center dot toluene are reported.