Oxidation-promoted synthesis of ferrocenyl planar chiral rhodium(iii) complexes for C–H functionalization catalysis

The chemical oxidation of rhodium(i) complexes Rh(L)(COD)]BF4], where L is a ferrocenyl phosphine/N-heterocyclic carbene ligand, with 2 equiv. of a triaryl-aminium salt (4-BrC6H4)3N]BF4] in acetonitrile gave planar chiral, air-stable Rh(L–H)(MeCN)3]BF4]2 complexes where the ferrocene (C5H4CH2ImR or C5H4CH2BImCH2Mes) ring has been C–H activated at the position 2 in good to excellent yields. An important reactivity difference between our complexes and the ubiquitous Cp*Rh(MeCN)3]X2 complex has been observed in the Grignard-type arylation of 4-nitrobenzaldehyde.