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

The divalent organosamarium complex (C5Me5)2Sm(THF)2 (1) reacts in toluene with Me3CCN to form the insoluble trivalent cyanide complex [(C5Me5)2SmCN]n (2). The Me3CCN reaction was found to proceed through divalent (C5Me5)2Sm(NCCMe3)(THF)x (3). The bis(nitrile) analogue of 3, (C5Me5)2Sm(NCCMe3)2(THF) (4), is isolable from the reaction of 1 with Me3CCN 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 (C5Me5)2Sm(NCHCMe3)(THF) (5). Complex 5 is the product of insertion of Me3CCN into a Sm−H bond presumably formed by β-hydrogen elimination of a Me3C 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 [(C5Me5)2Sm(μ-H)]2 with Me3CCN and THF. Crystallographic data on the related nitrile adducts [(C5Me5)2Sm(NCCMe3)(μ-CN)]3 (6) and [(C5Me5)2Sm(NCCMe3)]2(μ-O) (7) are also reported.