Cd(VO2)4(SeO3)3•H2O:: A new bimetallic vanadium selenite compound with heptacoordinated cadmium ion

A new bimetallic selenite compound, Cd(VO2)(4)(SeO3)(3) . H2O, with vanadium and cadmium metals was synthesized from hydrothermal reactions Of V2O5, Cd(NO3)(2). 2H(2)O, and SeO2 in water at 230 degreesC. This compound crystallizes in a triclinic unit cell with the space group P (1) over bar (No. 2) and the lattice parameters a = 6.2999(4) Angstrom, b = 7.4078(4),Angstrom, c = 15.7525(9) Angstrom, alpha = 100.881(1)degrees, beta = 98.796(1)degrees, gamma = 93.690(1)degrees, V = 710.14(7) Angstrom (3), Z = 2. The crystal structure was determined by X-ray single-crystal diffraction techniques and was refined with R = 0.0336 and wR(2) = 0.0819 for all 3175 reflection data. The structure can be described as layers with pillars between the layers. The layer is composed of dimers of VO5 square pyramids and dimmers of CdO7 decahedra connected to one another by sharing corner and/or edge oxygen atoms, and the pillars are composed Of VO6 distorted octahedra connected to one another with capping SeO32- selenite groups. The coordination number of Cd atom in the structure shows a rare example of hepta-coordination with only oxygen donor atoms. (C) 2001 Academic Press.