Manganese(IV) complex with a polydentate Schiff base ligand: synthesis,crystal structure,TDDFT calculation,electronic absorption and EPR spectral study

A six-coordinate Mn(IV) complex, Mn(H₂L)₂] (1) H₄L = 2-methoxy-6-(tris(hydroxymethyl)methyliminomethyl)phenol], was synthesized and characterized by elemental analysis, single-crystal X-ray crystallography, FTIR, UV–Vis electronic absorption, and EPR spectroscopy. The single-crystal structural determination reveals that the complex crystallizes in tetragonal space group P4₁2₁2 and the tridentate Schiff base ligands are arranged in mer configuration chelating manganese, which exhibits as slightly distorted octahedral coordination sphere with a N₂O₄ chromophore. Weak hydrogen bonding interactions of uncoordinated hydroxyl groups result in a 2-D supramolecular structure. The UV–Vis electronic absorption and IR spectral data of 1 have been compared with the results obtained by employing DFT and time-dependent density functional theory calculation using B3LYP, B3PW91, and MPW1PW91 functionals, with 6-31G (d-p) and LanL2MB basis sets. The results of these calculations are functional-dependent and, among those used, B3PW91 proved to better reproduce the experimental results.