Synthesis, crystal structure and properties of a novel di-μ2-aqua bridged binuclear manganese(III) Schiff base complex [Mn(vanen)(H2O)2]2(ClO4)2 · 2H2O

Abstract

The preparation and isolation of the binuclear manganese(III) complex, [Mn(vanen)(H2O)2]2(ClO4)2 · 2H2O was accomplished by air oxidation of a solution containing H2vanen**, Et3N, and Mn(ClO4)2 · 6H2O in absolute EtOH. The crystal structure of complex was determined by X-ray crystallography, and consists of two molecules bridged by two water molecules through hydrogen bonding. The manganese atom is six-coordinate and presents a distorted octahedral coordination sphere, which consists of the two imine N atoms and two phenolic O atoms of vanen2− ligand in the equatorial plane, with Mn–N bond distances of 1.975 and 1.987 A, and Mn–O distances of 1.867 and 1.876 A, respectively. The non-bonding interatomic Mn⋯Mn distance is 4.79 A. In the axial direction, the elongated Mn–O(H2O) bond distances of 2.255 and 2.381 A, respectively, are due to Jahn–Teller distortion at the d4 metal center. The presence of lattice and coordinate water molecules were also confirmed by the t.g. study and the i.r. spectra. Upon irradiation using visible light in water in the presence of p-benzoquinone, the complex demonstrates its ability to split water.