Biologically relevant metal coordination compounds: Mo VIO 2 and nickel(II) complexes with tridentate aromatic schiff bases

Abstract

The synthesis and characterization of two monomeric tridentate Schiff base complexes, Ni II( o-O-C 6H 4CNC 6H 4- o-S)(4-Bu t-C 5H 4N) ( 1) and Mo VIO 2(2-O-C 10H 6CNC 6H 4- o-S)(CH 3SO CH 3) ( 2), is presented. The structure of both compounds has been determined by X-ray crystallography. Two terminal oxo groups cis to each other strongly influence the distorted octahedral geometry of the molybdenum complex 2. Additionally, the tridentate dibasic Schiff base ligand coordinated to the dioxomolybdenum core exhibits an unusually large dihedral angle along the CN bond of 40°. By way of contrast, the nickel complex 1 exhibits a nearly regular square planar coordination geometry in which the dihedral angle in the coordinated tridentate Schiff base ligand is only 1.3°. Different influences of tridentate dibasic Schiff base ligands on the geometry and solution chemistry of nickel(II) and Mo VIO 2 complexes are discussed. The value of these ligands for the synthesis of model compounds of metalloenzymes is evaluated. The thermal decomposition (TG/MS) of the dimeric derivative of 1 is discussed.