Reactivity of (C₅Me₅)₂Sm(THF)₂ with Nitriles:  C−C Bond Cleavage To Form Cyanide Complexes

The divalent organosamarium complex (C 5 Me 5 ) 2 Sm(THF) 2 ( 1 ) reacts in toluene with Me 3 CCN to form the insoluble trivalent cyanide complex [(C 5 Me 5 ) 2 SmCN] n ( 2 ). The Me 3 CCN reaction was found to proceed through divalent (C 5 Me 5 ) 2 Sm(NCCMe 3 )(THF) x ( 3 ). The bis(nitrile) analogue of 3, (C 5 Me 5 ) 2 Sm(NCCMe 3 ) 2 (THF) ( 4 ), is isolable from the reaction of 1 with Me 3 CCN in THF and has been characterized by X-ray crystallography. Both 3 and 4 transform via C−C bond cleavage to form the cyanide product 2 and (C 5 Me 5 ) 2 Sm(N CHCMe 3 )(THF) ( 5 ). Complex 5 is the product of insertion of Me 3 CCN into a Sm−H bond presumably formed by β-hydrogen elimination of a Me 3 C intermediate. Complexes 2 and 5 can also be generated by the stoichiometric reaction of crystalline 4 with 1 in toluene. Complex 5 can be synthesized directly from the reaction of [(C 5 Me 5 ) 2 Sm(μ-H)] 2 with Me 3 CCN and THF. Crystallographic data on the related nitrile adducts [(C 5 Me 5 ) 2 Sm(NCCMe 3 )(μ-CN)] 3 ( 6 ) and [(C 5 Me 5 ) 2 Sm(NCCMe 3 )] 2 (μ-O) ( 7 ) are also reported.