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

Two homotrinuclear Co(II) complexes, [Co-3(L)(OAc)(2)(CH3OH)(2)](2)CHCl3 (1) and [Co-3(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 O-4 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 (3,5DTBC) 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.