A novel cobalt(II) complex with polyoxometalate-based ligand by virtue of coexistence of both a capped-Keggin anion and a neutral unit

A new bicapped Keggin heteropolyoxoanion derivative [Co(bpy)(3)](2)[(PMo8V3VO40)-V-VI-V-V-O-IV((VO)-O-IV)(2)] [{Co(bpy)(2)(H2O)}(2){(PMo8V3VO40)-V-VI-V-V-O-IV((VO)-O-IV)(2)}] (.) 8H(2)O (1) (bpy = 2,2'-bipyridine), has been hydrothermally synthesized and structurally characterized by elemental analysis, single crystal X-ray diffraction, IR and X-ray photoelectron spectra. Complex 1 consists of two [Co(bpy)(3)](2+) cations, an anion of [(PMo8V3VO40)-V-VI-V-V-O-IV((VO)-O-IV)(2)](4-) and a neutral unit [{Co(bpy)(2)(H2O)}(2) {(PMo8V3VO40)-V-VI-V-V-O-IV((VO)-O-IV)(2)}] in which {(PMo8V3VO40)-V-VI-V-V-O-IV((VO)-O-IV)(2)}(4-) is coordinated to two Co atoms through its terminal oxygen atoms of the two capping V atoms at opposite sites together with bipyridine and water ligands. The most interesting feature of 1 is that a polyoxoanion and a neutral component coexist in the crystal structure. Hydrogen-bonding contacts are also formed between different polyanions through the lattice water molecules.