Organo-functionalized metal–oxide clusters: synthesis and characterization of the reduced cationic species [NaVIV6O6{(OCH2CH2)2NH}6]+

Abstract

A new heteropolyoxovanadium compound, [NaV₆O₆{(OCH₂CH₂)₂NH}₆]·(OH)_0.5Cl_0.5·3(H₂O), was synthesized and characterized by single-crystal X-ray diffraction analysis, cyclic voltammetry, FTIR and UV-vis spectroscopy, and TGA. [NaV₆O₆{(OCH₂CH₂)₂NH}₆]·(OH)_0.5Cl_0.5·3(H₂O) contains the diethanolamine functionalized oxovanadium cationic cluster, [NaV^IV₆O₆{(OCH₂CH₂)₂NH}₆]⁺. The cluster cation is composed of a fully reduced cyclic {NaV₆N₆O₁₈} framework which adopts an Anderson-like structure and is comprised of a ring of six edge-sharing {VO₅N} octahedra linked to a central {NaO₆} unit. Two (OCH₂CH₂–) arms of each of the six diethanolamine ligands are incorporated into the oxometalate core. FTIR spectra are consistent with the presence of expected VO_t stretching modes and functionalization with diethanolamine. Electrochemical and UV-vis absorption properties are consistent with two distinct MLCT processes: the characteristic VO_t dπ–pπ interaction, and a second process occurring through the hydrogen-terminated nitrogen atoms (V–N–H) of the octahedra forming the cyclic {NaV₆N₆O₁₈} core.