Dinitrogen Silylation and Cleavage with a Hafnocene Complex

Silylation of a hafnocene complex containing a strongly activated dinitrogen ligand, [(η(5)-C(5)H(2)-1,2,4-Me(3))(2)Hf](2)(μ(2),η(2),η(2)-N(2)), by addition of CySiH(3) resulted in N-Si and Hf-H bond formation and a compound poised for subsequent N(2) cleavage. Warming the silane addition product to 75 °C triggered N-N scission, for which the requisite electrons were provided by silyl migration. Dinitrogen cleavage coupled to N-C bond formation was also accomplished by carbonylation of the silylated product, yielding an unprecedented μ-formamidide ([NC(H)O](2-)) ligand. Subsequent treatment with HCl yielded free formamide, demonstrating that an important organic molecule can be synthesized from N(2), CO, an organosilane, and protons.