Mn(IV), Co(II) and Ni(II) complexes of the Schiff bases of 2-hydroxy-naphthaldehyde with amino alcohols: synthesis, characterization and electrochemical study; DFT study and Catecholase activity of Mn(IV) complex

Abstract

Four new mononuclear complexes, [MnIV(L1)2] (1), [CoII(HL1)2] (2), [NiII(HL1)2] (3), and [NiII(HL2)2] (4), with ligands H2L1 (2-hydroxyethylimino)methylnaphthol) and H2L2 (3-hydroxy propylimino)methylnaphthol) have been synthesized, characterized, and their catecholase activities have been studied. Single-crystal X-ray diffraction study shows that 1 crystallizes in P43212 space group and adopts an octahedral geometry in meridional fashion, whereas 4 with a square planar geometry crystallizes in P21/n space group. The catecholase activity has been investigated in acetonitrile by UV-Vis spectrophotometric technique. The kinetic study revealed that 1 has a moderate catecholase activity (k cat = 812 h−1), whereas 2–4 are inactive. Electronic structure of 1 and 4 has been established by theoretical calculation. Structures of both complexes have been optimized by DFT. Experimental electronic spectra of the complexes have been corroborated by TD-DFT analysis.