Theoretical studies of the interaction of butadiene with Rh and Rh2

Butadiene–Rh and –Rh2 complexes have been studied using the density functional (DFT) and Møller–Plesset (MP2 and MP4) calculations. For the butadiene–Rh complex complete active space multiconfiguration self-consistent field method (CASMCSCF) followed by multireference singles and doubles (MRSDCI) calculations were employed. Two nearly degenerate structures were found as candidates for the ground state of the butadiene–Rh complex with a five-member planar ring structure and a trans non-planar structure. The ground state of the butadiene–Rh2 complex was found to be a 1A′ state in a half-boat equilibrium structure.