Chirality and Relativistic Effects in Os(CO).

The energy and structural parameters were obtained for all forms of the carbonyl complex of osmium Os(CO) with D and D symmetries using density functional theory (DFT) methods. The calculations took into account various levels of relativistic effects, including those associated with nonconservation of spatial parity. It was shown that the ground state of Os(CO) corresponds to the D symmetry and thus may be characterized either as left-twisted (D) or right-twisted (D). The D↔D transitions occur through the D transition state with an activation barrier of ~10 kJ/mol. Parity violation energy difference (PVED) between D and D states equals to ~5 × 10 kJ/mol. An unusual three-center exchange interaction was found inside the {Os} fragment. It was found that the cooperative effects of the mutual influence of osmium atoms suppress the chirality of the electron system in the cluster.