Syntheses, crystal structures and catalytic activities of two solvent-induced homotrinuclear Co(II) complexes with a naphthalenediol-based bis(Salamo)-type tetraoxime ligand

Abstract

Two homotrinuclear Co(ii) complexes, [Co3(L)(OAc)2(CH3OH)2] 2CHCl3 (1) and [Co3(L)(OAc)2(H2O)2] (2) based on a naphthalenediol-based acyclic bis(Salamo)-type tetraoxime ligand were synthesized. 1 and 2 were influenced by the coordinated methanol and water molecules, respectively, and their X-ray crystal structures revealed that they have similar molecular structures. Two terminal Co(ii) ions, located at the N2O2 coordination spheres of the Salamo moieties, are both in distorted trigonal-bipyramidal geometries, while the third Co(ii) ion in the central O4 cavity shows an octahedral geometry with two solvent molecules placed in the apical sites. Different solvent molecules lead to different supramolecular structures. The catecholase activities of 1 and 2 were examined using 3,5-di-tert-butylcatechol (3,5-DTBC) in acetonitrile solution under completely aerobic conditions. The catalytic reaction follows Michaelis-Menten enzymatic reaction kinetics with turnover numbers (Kcat) of 14.72 h-1 and 26.39 h-1 for 1 and 2, respectively.