Theoretical study of the Ru + N2 molecular interaction

The results of Hartree–Fock (with relativistic effective core potentials) followed by variational and second order multireference perturbational configuration interaction (CIPSI) calculations are reported for the linear (C∞v) and bent (C2v) electronic states of the RuN2 molecule which arise from the ground state Ru(5F;d7s1) + N2 and the first excited state Ru(3F;d7s1) + N2 of the free fragments. For both coordination modes, the most important metal–ligand interaction channels are obtained for those states correlating with the low-multiplicity asymptotic limit. Due to the existence of symmetry-avoided crossings involving the potential energy curves which evolve from the second-lying triplet state of the separated fragments, Ru(3F;d8) + N2, the ability of ruthenium to capture the N2 molecule through these low-multiplicity channels is strongly determined by the maximal d-shell occupancy metallic state.