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

Two homotrinuclear Co( ii ) complexes, [Co 3 (L)(OAc) 2 (CH 3 OH) 2 ] 2CHCl 3 ( 1 ) and [Co 3 (L)(OAc) 2 (H 2 O) 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 N 2 O 2 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 (3,5-DTBC) in acetonitrile solution under completely aerobic conditions. The catalytic reaction follows Michaelis-Menten enzymatic reaction kinetics with turnover numbers ( K cat ) of 14.72 h −1 and 26.39 h −1 for 1 and 2 , respectively. Two homotrinuclear cobalt( ii ) complexes with different solvent molecules that coordinate to the central Co( ii ) ion, show different supramolecular interactions and exhibit catalytic activities in relation to catechol oxidase.