Transition metal complexes: VIII. An unusual rearrangement of a butadienyl ligand via cyclometallation☆

Abstract Cp★Ni(η 1 ,η 2 -C 4 HPh 4 ) (Cp★ = η 5 -C 5 -Me 5 ) ( 1 ) was prepared by reacting Cp★Ni(acac) with 1,4-dilithium-1,2,3,4-tetraphenylbutadiendiyl and its structure determined by X-ray diffraction. Thermolysis of 1 in THF affords Cp★Ni(η 3 -1-benzyl-2,3-diphenylindenyl) ( 2 ) and Cp★Ni(η 3 -3-benzylyl-1,2-diphenylindene) ( 3 ). The structures of 2 and 3 were also determined by X-ray diffraction. A proposed mechanism of product formation is discussed.