C-CN bond activation of benzonitrile with [Rh -I(dippe)] -

Article abstract of DOI:10.1021/om200342f

The complex [Rh(dippe) (μ-Cl)]₂ (1) was reduced with potassiummetal to produce the highly reactive Rh^-I species [Rh(dippe) (μ-K 3 THF)]₂ (2). 2 was characterized by NMR spectroscopy ( ₃₁P, ₁H) and IR spectroscopy after forming the derivative K[Rh(dippe) (CO)₂] (2a). The C-CN bond of benzonitrile was cleaved by oxidative addition when it was reacted stoichiometrically with 2 to form the anionic Rh(I) complex K[Rh(dippe) (CN) (Ph)] (3). 3 has been characterized by NMR spectroscopy (₃₁P, ₁H, ₁₃C), and by the use of ₁₃C-labeled benzonitrile. C-CN bond cleavage was also attempted by reacting benzonitrile with the zwitterionic complex [Rh(dippe) (μ6-Ph-BPh3)] (4). A product 5 was formed from reaction with 2 equiv of benzonitrile. Reaction with ₁₃C-labeled benzonitrile has ruled out the possibility of C-CN cleavage in this species, and a C-Hbond activation pathway is operative instead.