Theoretical modeling of the L2,3-edge X-ray absorption spectra of Mn(acac)2 and Co(acac)2 complexes.

Mn(acac)2 (I) and Co(acac)2 (II) L2,3-edge absorption spectra have been modeled using the DFT/ROCIS method. In addition to the agreement between experiment and theory, the combined use of the B3LYP exchange-correlation functional and the def2-TZVP(-f) basis set provided useful information about the coordinative geometry around the M(ii) ions as well as about the nature and the strength of the Mn-O and Co-O interaction. The lower excitation energy (EE) side of both (I)(/)(II)L3 and (I)(/)(II)L2 intensity distributions mainly includes states having ground state spin multiplicity (S = 5/2 in I and S = 3/2 in II), whereas states with lower spin multiplicity (S = 3/2 in I and S = 1/2 in II) significantly contribute to the higher EE side of both (I)(/)(II)L3 and (I)(/)(II)L2. Hence, the occurrence of states involving metal to ligand charge transfer transitions in the presence of ligands with low lying empty π* orbitals on the L3 and L2 higher EE sides is herein confirmed.