Molecular properties of coordination compounds of the croconate ion with first-row sivalent transition metals: a quantum mechanical study

In this paper we report geometries, magnetic and vibrational spectroscopic properties of croconate complexes [M(C5O5)(H2O)4] (M= Mn2+, Fe2+, Co2+, Ni2+, Cu2+ and Zn2+) calculated at the Density Functional Theory level. The ground state of all complexes was found to be of high spin, in accordance with the experimental proposal. The calculated structures and vibrational frequencies were also in agreement with experiment, even though comparisons were made with the solid state structure. The calculated nonlinear optical (NLO) properties were for all the compounds analyzed, using the Time Dependent Hartree-Fock (TDHF) method within the static approach, suggesting that these transition metal complexes might be considered as lead molecules to the development of novel based-molecular materials.