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

Abstract

Hydrothermal reactions of CuSO 4·5H 2O, MoO 3 and tetra-2-pyridylpyrazine (tpyrpyz) yield the three-dimensional bimetallic oxide hybrid material [{Cu 2(tpyrpyz)} 2{ζ-Mo 8O 26}]·7H 2O ( 1·7H 2O). The framework structure is constructed from {Cu 2(tpyrpyz)} n 2 n+ cationic polymer chains linked through octamolybdate clusters. The ζ-isomer of {Mo 8O 26} 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 {Mo 8O 26} 4− cluster, and calculations of their relative energies and interconversions are presented. Crystal data: C 48H 46Cu 4Mo 8N 12O 33 ( 1·7H 2O), monoclinic C2/ c, a=26.678(1), b=10.8981(4), and c=25.4109(9) Å, β=116.855(1)°, V=6591.2(4) Å 3, Z=4, D calc=2.359 g cm −3.