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[VIVO40(VIVO)2] [{Co(bpy)2(H2O)}2{VIVO40(VIVO)2}] · 8H2O (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 [VIVO40(VIVO)2]4− and a neutral unit [{Co(bpy)2(H2O)}2{VIVO40(VIVO)2}] in which {VIVO40(VIVO)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.