Hydrothermal syntheses and structural characterization of two novel arsenic-vanadium clusters:: [Co(2,2′-bpy)3]2[As8V14O42(H2O)]•3H2O and [2,2′-bpy][Ni(2,2′-bpy)3]2[As8V14O42(H2O)]•3H2O

Two new arsenic -vanadium clusters, [Co(2,2'-bpy)(3)](2)[As8V14O42(H2O)]center dot 3H(2)O (1), [2,2'-bpy][Ni(2,2'-bpy)(3)](2)[As8V14O42(H2O)]center dot 3H(2)O (2) (2,2'-bpy = 2,2'-bipyridine), have been hydrothermally synthesized and characterized by IR, elemental analysis, UV-VIS, EPR, TGA, XPS, and single crystal X-ray diffraction analysis. Crystal data: 1, triclinic, P(1) over bar, a = 14.368(3) angstrom, b = 16.753(3) angstrom, c = 24.632(5) angstrom, alpha = 94.15(3)degrees, beta = 93.16(3)degrees, gamma = 113.05(3)degrees, Z = 2; 2, monoclinic, P2(1)=c, a = 30.2150(4) angstrom, b = 14.0690(3) angstrom, c = 26.0536(3) angstrom, beta = 106.8960(10)degrees, Z = 4. X-ray crystallographic studies showed that crystals 1 and 2 are both composed of discrete cluster anion [As8V14O42(H2O)](4-) and transition metal coordination complexes [M(2,2'-bpy)(3)](2+) (M = Co or Ni). Interestingly, compound 2 contains another neutral organic space filler of 2,2'-bpy. To the best of our knowledge, compounds 1 and 2 are the first examples of structurally characterized vanadium/2,2'-bpy/arsenate polyoxometallates.