The theoretical study on the coumarin-based Mn(II) complex

Coumarins (2H—benzo—pyran—2—ones) derivatives, constitute a unique class of fused ring heterocycles that have attracted significant attention owing to their widedistribution in nature [1]. Several natural compounds containing this heterocyclic framework exhibit interesting biological and pharmacological properties [2]. In the present work, the structure of Mn(Couma—H )2(MeOH)2 (Fig. 1) was investigation theoretically and the results of experimental [3] and theoretical were compared with each other. Full geometry optimization of the crystal structure of Mn(ll) complex was carried out using Gaussian 09 suite of program package at B3LYP/6—31G level of theory in the gas phase. Density functional theory (DFT) simulation was used to further understand the electronic structure of Mn(ll) complex. The results show that the molecule lies on a center of symmetry. The Mn ion is 6—coordinated bonded to two monodeprotonated, bidentate ligands, which form 6—membered chelate rings. The coordination sphere is completed by two methanol molecules hydrogen bonded to the oxygen of a neighboring molecule. The values of bond lengths and angles calculated with B3LYP method are in agreement with the experimental crystal structure. However, for this complex, the ribbon structure is reinforced by some TC- interactions involving carbonyl groups of the coumarin and there are no significant inter—ribbon interactions.