An organo-functionalized metal-oxide cluster, [VO₆{(OCH₂CH₂)₂N(CH₂CH₂OH)}₆], with Anderson-like structure

A new polyoxovanadium cluster compound, [VO₆{(OCH₂CH₂)₂N(CH₂CH₂OH)}₆]·0.5CH₃CN, was synthesized and characterized by single-crystal X-ray diffraction analysis, FTIR and UV-vis spectroscopy, and TGA. The cluster is composed of a fully reduced cyclic {V₆N₆O₁₈} framework, which adopts an Anderson-like structure and is comprised of a ring of six edge-sharing {VO₅N} octahedra incorporating six {(OCH₂CH₂)₂N(CH₂CH₂OH)} ligands. Two (OCH₂CH₂-) arms of each of the six triethanolamine ligands are directly incorporated into the oxometalate core and the third {-CH₂CH₂OH} arm remains pendant. In the condensed phase, the clusters form discrete hcp layers through inter-cluster hydrogen bonding. These layers stack through soft chemical interactions to form a 3D network structure. The neutral cluster, [VO₆{(OCH₂CH₂)₂N(CH₂CH₂OH)}₆], is the isopolyoxovanadium analogue to the cationic clusters contained in a series of heteropolyoxovanadium compounds previously introduced by our laboratory, e.g., [LiVO₆{(OCH₂CH₂)₂N(CH₂CH₂OH)}₆]⁺; its existence shows that a heteroatom is not required to form or stabilize the common organofunctionalized vanadium oxide framework: [VO₆{(OCH₂CH₂)₂N(CH₂CH₂OH)}₆]. To the best of our knowledge, the isopolyoxovanadium and heteropolyoxovanadium clusters represent the first reported isopoly-heteropoly analogues in the polyoxometalate field. We compare the TGA profile, FTIR and UV-vis spectra of the new compound with two of its cationic heteropoly analogues.