The oxygen-atom transfer reactions of Mo-diselenolene biomimetic complexes: A computational investigation

Abstract

The aqueous Gibbs reaction and activation energies for the O-atom transfer mechanism of several Mo-bis(diselenolene) biomimetic complexes was investigated. The results obtained for the Mo-diselenolene biomimetic complexes were compared to analogous Mo-dithiolene biomimetic complexes to determine the effect of using Se-donor atoms vs. S-donor atoms. From the calculated value of ΔrG the exergonicty for the oxidation of sulfite is essentially unchanged with the substitution of the S-atoms with Se-atoms in the dithiolene ligands. Moreover, from the results the Mo-diselenolene biomimetic complexes catalyse the O-atom transfer with essentially the same value of ΔrG‡ seen for the analogous dithiolene complexes. In particular, on average the diselenolene complexes have on average a barrier only 0.5 kJ mol−1 higher in energy than the analogous dithiolene complexes. Lastly, it was found that the O-atom transfer was marginally affected by the choice of non-transferring ancillary ligand. The likely, reason being that the donor atom of the non-transferring ligand had a marginal contribution to the LUMO+1 of the Mo-complexes. Moreover, the ligand trans to the transferring O-atom was a donor atom from diselenolene or dithiolene ligand.