Preparation and molecular structure of binuclear nickel( II) complex bridged by 1,2, 4, 5-benzenetetracarboxylato tetravalent anion

The title complex [(H2O)(2)(IMI)(3)Ni(TCB) Ni(IMI)(3)(H2O)(2)] H2O (TCB = 1 ,2, 4, 5-benzenetetracarboxylato tetravalent anion; IMI = imidazole) has be en prepared by the reaction of Ni(IMI)3(AC)2 and TCB in aqueous solution. T he crystal structure has been determined by single-crystal X-ray diffractio n method. It crystallizes in the monoclinic system, space group P2(1)/c(# 1 4), a = 1.2714(4) nm, b = 0.9411 (3) Nn, c = 1.5869(4) nm, beta = 108.54(2) degrees, V = 1.8001(9) nm(3), Z = 2. The main feature of the crystal struct ure is a symmetric binuclear unit made up of two slightly distorted coordin ation octahedrons, which are bridged by TCB in monodentate fashion to each metal ion, Moreover three nitrogen atoms from three imidazoles, three oxyge n atoms from two water molecules and one carboxylate group of TCB coordinat ed to a nickel( Il) ion are found on a face of the octahedron respectively, so the octahedron is a facial isomer.