Ab initio multireference calculation of electronic spectra of the osmium complexes, [Os(bpy)3$$ {}_3 $$]2+$$ {}^{2+} $$ and [Os(phen)3$$ {}_3 $$]2+$$ {}^{2+} $$

AbstractThe spin‐orbit coupling corrected absorption spectra of osmium complexes, [Os(bpy)] and [Os(phen)], were calculated by using ab initio multireference perturbation method (NEVPT2) with relativistic effects taken into account throughout ZORA approximation and corresponding all‐electron basis sets. For the same purpose, the time‐dependent DFT techniques were used. A very good agreement between NEVPT2 and experimental spectra should be highlighted, especially for the MLCT transitions that occur in visible and near‐UV regions ( cm). Moreover, the present study offers description of excited states of titled osmium complexes and their spectra interpretation using molecular orbitals.