Isocyanate deinsertion from κ1-O amidates: facile access to perfluoroaryl rhodium(i) complexes

Abstract

Reaction of the amidate ligand salt, Na[N(Dipp)C(O)C₆F₅] (1) (Dipp = 2,6-diisopropylphenyl) with [Rh(NBD)Cl]₂ (NBD = norbornadiene) results in formation of the dirhodium(I) complex [Rh₂{μ₂-N,O-N(Dipp)C(O)C₆F₅}₂(NBD)₂] (2). Reaction of 2 with PCy₃ at room temperature provides an equilibrium mixture of the geometric isomers (E/Z)-[Rh{κ¹-O-N(Dipp)C(O)C₆F₅}(NBD)(PCy₃)] (E/Z-3). Treatment of 2 with 3 equiv. of CNXyl (Xyl = 2,6-dimethylphenyl) gives the κ¹-O complex [Rh{κ¹-O-N(Dipp)C(O)C₆F₅}(CNXyl)₃] (6) while use of 3 equiv. of PPh₃ provides the κ²-complex [Rh{κ²-N,O-N(Dipp)C(O)C₆F₅}(PPh₃)₂] (8). For complex κ²-N,O8, an equilibrium results with free PPh₃ giving the κ¹-O complex [Rh{κ¹-O-N(Dipp)C(O)C₆F₅}(PPh₃)₃] (9). Heating a tol-d₈ solution of E/Z-3, 6, or 8/9 results in 2,6-diisopropylphenylisocyanate extrusion providing the corresponding [Rh]-C₆F₅ complex in good yield.