Metallabenzene versus Cp Complex Formation: A DFT Investigation

One common reaction that metallabenzene complexes undergo is the formation of cyclopentadienyl (Cp) complexes. Density functional theory (DFT) was used here to investigate the reaction mechanism. It was found that the reaction can proceed via a carbene migratory insertion class of C-C coupling. Cp complexes are found to be thermodynamically favored, except for the case of (C5H5Ir)(PH3)2Cl2 (1j) where the metallabenzene was favored. Isolation a rhodiabenzene of the type (C5H5Rh)(PH3)2Cl2 (1m) and a palladiabenzene, such as (C5H5Pd)Cp (1p), may be possible.