Synthesis and characterization of rhodium(I) 2-methylcupferrate complexes and their kinetic behaviour in iodomethane oxidative addition

A number of substituted monocarbonyl complexes [Rh(MeCupf)(CO)(PR3)] (where R = Ph, p-MeOph, p-Tol, o-Tol and Cy, MeCupf = N-nitroso-N-(2-methylphenyl)hydroxylaminato bidentate ligand) have been prepared from [Rh(MeCupf)(CO)2] and identified by IR, UV/visible and NMR techniques. The kinetics and mechanism for the oxidative addition of iodomethane to [Rh(MeCupf)(CO)(PR3)] complexes have been investigated through the variation of steric and electronic effects of the phosphine ligands, as well as through varying the solvent and temperature. The RhIII–alkyl complex was the primary species formed as a result of oxidative addition, followed by a consecutive slower formation of the RhIII–acyl species by carbonyl-insertion. A detailed mechanism is discussed.