An AB Initio Study of the Electronic and Geometric Structure of BIS-of Dipivaloylmethane With Manganese, IRON, and Cobalt

Abstract

An ab initio study of the structure of Mn(thd)2, Fe(thd)2, and Co(thd)2 complexes in different electronic states is carried out. Quantum chemical calculations are performed using the PC GAMESS program with relativistic effective core pseudopotentials and Gaussian valence triple-zeta basis sets. Calculation methods: DFT/ROB3LYP and CASSCF followed by the inclusion of dynamic electron correlation through multiconfiguration quasi-degenerate second order perturbation theory (MCQDPT2). All three complexes are shown to have a low-spin electronic ground state with a planar structure of the bicyclic fragment at D2h molecular symmetry. The M—O bond is mainly ionic, and M(thd)2 molecules can be considered as an M2+ cation coordinated by two negatively charged bidentate ligands.