Structure of a mononuclear rhenium catalyst supported on MgO: An ab initio study

A theoretical study of a mononuclear catalyst precursor, the HRe(CO)(5) complex, both isolated and adsorbed on the MgO (100) surface is reported. Ab initio calculations have been performed at the RHF and CASSCF levels of theory using a basis set of at least double-zeta. quality. To represent the surface three different clusters have been selected: OMg58+, O5Mg5 and O9Mg58-. The environment effects are introduced by embedding these clusters in a set of total ion potentials and point charges. At the RHF level, the organorhenium complex does not bind to the surface due to an overestimation of its dipole moment while at the CASSCF level, a large adsorbate-surface interaction is found. Vibrational frequencies for the isolated complex have been computed and found to agree with the experiment.