The RuO2+ moiety is at the root of many important single-site polypyridyl catalysts demonstrated to either reduce CO2 or oxidize H2O. These processes are important in many contexts, but are particularly important in the development of high performance dye-sensitized photoelectrosynthesis cells loosely based on the Gr�tzel cell.  This work augments the large and growing volume of theoretical research on these systems by focusing on how the details of spin-orbit coupling and select relativistic terms affects bonding and excited state energies for these heavy element containing species, ultimately seeking to predict how to replace such elements with earth abundant alternatives.  RuO2+ and OsO2+ are represented by accurate basis sets of Gaussian-type functions and relativistic effective core potentials that include spin-orbit operators for Ru and O. The configuration interaction (CI) space is constructed from a reference valence complete active space multiconfiguration self-consistent field (CASSCF) molecular orbitals to which are added all single and doubles excitations (SD) to the remaining (virtual) MOs.  Further, CASSCF-SD CI results with and without the SO operators included are compared. For each system, a manifold of excited states are calculated. These results demonstrate that the energies of of OsO2+ and RuO2+ singlet ground and triplet excited states are very close in energy, with their differences being of the the order of that due to spin-orbit coupling.  The prediction of a diamagnetic ground state of RuO2+ is consistent with experimental observations for the polypyridyl complex.

Comparative analysis of the electronic structures of RuO<sup>2+</sup> and OsO<sup>2+</sup> using the spin-orbit configuration interaction method

246th National Meeting (2013)

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Comparative analysis of the electronic structures of RuO2+ and OsO2+ using the spin-orbit configuration interaction method

Comparative analysis of the electronic structures of RuO²⁺ and OsO²⁺ using the spin-orbit configuration interaction method