An oxide chain constructed from octamolybdate, a Keggin anion and a copper (II) – Tetrapyridylpyrazine binuclear unit

The hydrothermal reaction of MoO3, CuSO4·5H2O, tetra-4-pyridylpyrazine (tpyprz), and diphenyldiarsonic acid in water at 140 °C for 48 h yielded the one-dimensional material [{Cu2(tpyprz)(H2O)3}2{Mo8O26}{Mo12O36(AsO4)}]·8H2O (1·8H2O). The chain structure of 1·8H2O is constructed from alternating β-octamolybdate clusters and molybdoarsonate Keggin clusters linked through {Cu2(tpyprz)(H2O)3}4+ binuclear subunits. The Cu(II) sites are inequivalent with one copper bonding to two pyridyl donors and a pyrazine nitrogen of one terminus of the tpyprz ligand, two aqua ligands and an oxo-group of the image cluster while the second copper site coordinates to the nitrogen donors of the other terminus of the tpyprz ligand, an aqua group, a terminal oxo-group of the image cluster and a terminal oxo-group of the mixed valence {Mo11VIMoVO36(AsO4)}4− cluster. Crystal data: C48H60AsCu4Mo20N12O80: FW = 4332.96 Triclinic image, a = 12.5087(5) Å, b = 13.6681(6) Å, c = 14.8980(6) Å, α = 92.196(1)°, β = 97.046(1)°, γ = 97.751(1)°, Z = 1, Dcalc = 2.877 g cm−3; structure solution and refinement based on 12,333 reflections (Mo Kα, λ = 0.71073 Å) converged at R1 = 0.0540 and wR2 = 0.1115.