A three-dimensional bimetallic oxide constructed from octamolybdate clusters and copper-ligand cation polymer subunits. A comment on the stability of the octamolybdate isomers

Hydrothermal reactions Of CuSO4.5H(2)O, MoO3 and tetra-2-pyridylpyrazine (tpyrpyz) yield the three-dimensional bimetallic oxide hybrid material [{Cu-2(tpyrpyz)}(2){zeta-Mo8O26}].7H(2)O (1.7H(2)O). The framework structure is constructed from {Cu-2(tpyrpyz)}(n)(2n+) cationic polymer chains linked through octamolybdate clusters. The zeta-isomer of {Mo8O26}(4-), consisting of four octahedral and four square pyramidal sites is present as the cluster building block. There are now seven isomeric forms of the {Mo8O26}(4-) cluster, and calculations of their relative energies and interconversions are presented. Crystal data: C48H46Cu4Mo8N12O33 (1.7H(2)O), monoclinic C2/c, a = 26.678(l), b = 10.8981(4), and c = 25.4109(9) Angstrom, beta = 116.855(l)degrees, V = 6591.2(4) Angstrom(3), Z = 4, D-calc = 2.359 g cm(-3). (C) 2003 Elsevier B.V. All rights reserved.