Extensive ab initio calculations have been carried out on benzene (Bz)-platinum complexes (Bz-Pt-2, Bz(2)-Pt, Bz(2)-Pt-2, and Bz(3)-Pt-2) using a variety of computational techniques. Both physisorbed structures and energetically lower chemisorbed species were found. Complete active space multiconfiguration self-consistent field (CASMCSCF), multireference singles and doubles configuration-interaction (MRSDCI), density functional (DFT), and Moller-Plessett second order perturbation (MP2) calculations were employed to predict Bz(m)-Pt-n structures. While the DPT and MP2 calculations also consistent with the MRSDCI techniques predict chemisorbed :structures to-be lower, the CASMCSCF method seems to favor physisorbed structures. The effect of spin-orbit. coupling on the binding energies of complexes with the Pt atom and the Pt-2 dimer were considered. The computed dissociation energies are consistent with the relative abundance of these clusters found in the time-of-flight mass spectra. The low-energy staircase structures of Bz(2)-Pt, Bz(2)-Pt-2, and Bz(3)-Pt-2 complexes found in this study could be electrically conducting.