An organo-functionalized metal–oxide cluster, [VIV6O₆{(OCH₂CH₂)₂N(CH₂CH₂OH)}₆], with Anderson-like structure

Abstract

A new polyoxovanadium cluster compound, [VO{(OCHCH)N(CHCHOH)}]·0.5CHCN, 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 {VNO} framework, which adopts an Anderson-like structure and is comprised of a ring of six edge-sharing {VON} octahedra incorporating six {(OCHCH)N(CHCHOH)} ligands. Two (OCHCH-) arms of each of the six triethanolamine ligands are directly incorporated into the oxometalate core and the third {-CHCHOH} 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, [VO{(OCHCH)N(CHCHOH)}], is the isopolyoxovanadium analogue to the cationic clusters contained in a series of heteropolyoxovanadium compounds previously introduced by our laboratory, e.g., [LiVO{(OCHCH)N(CHCHOH)}]; its existence shows that a heteroatom is not required to form or stabilize the common organofunctionalized vanadium oxide framework: [VO{(OCHCH)N(CHCHOH)}]. 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.

Spectroscopic, Crystallographic, and Electrochemical Study of Different Manganese(II)‐Substituted Keggin‐Type Phosphomolybdates

“…In order to further investigate the former measurements, UV/Vis spectra were measured (Figure 10). Since the scaffolding metal of a POM is generally present in its highest oxidation state, the HOMO‐LUMO excitation is usually a Ligand‐to‐Metal‐Charge‐Transfer (LMCT) transition [43–49] . HPA‐0‐0 does not contain another foreign metal atom, therefore only the O→Mo(VI)O 6 LMCT at 218 nm is visible in the UV/Vis spectrum (Table 6, Supporting Information) [44–46] .…”

“…Since the scaffolding metal of a POM is generally present in its highest oxidation state, the HOMO-LUMO excitation is usually a Ligand-to-Metal-Charge-Transfer (LMCT) transition. [43][44][45][46][47][48][49] HPA-0-0 does not contain another foreign metal atom, therefore only the O!Mo(VI)O 6 LMCT at 218 nm is visible in the UV/Vis spectrum (Table 6, Supporting Information). [44][45][46] The HOMO of the POMs is mainly localized on the terminal oxygen atoms (M=O t ), so that its energetic position is not particularly affected by changes in the HPA framework.…”

Atomically precise vanadium-oxide clusters

“…8a). [118][119][120] The disparity in cluster structure between Zubieta and Khan's complexes is likely due to ligand rigidity differences, with the rigid TRIS ligands unable to accommodate the ring structure, and the ethanolamine ligands' increased flexibility favouring the less sterically confined Anderson framework. The observed tridentate binding motif arises from a VO 5 N ligand sphere, with a single terminal oxo, four bridging alkoxo, and a capping N group (Fig.…”

“…8b ). 120 Two of the alkoxo groups are from the same ligand as the bound N; however, the other two are from the ligands of the neighbouring V ion, which gives rise to the cyclic framework. This distorted octahedral ligand environment, which is a consequence of the nature of these conformationally flexible organic moieties, disallows the formation of the Lindqvist core.…”

H8[PV5Mo7O40] – A Unique Polyoxometalate for Acid and RedOx Catalysis: Synthesis, Characterization, and Modern Applications in Green Chemical Processes

“…HPA‐0 appears yellow, the additional LMCT of vanadium in V V substituted phosphomolybdates shifts the color towards a darker red. The more V V is incorporated into the Keggin structure, the more intense the V V LMCT band becomes, whereas the Mo VI LMCT band loses intensity [70–72] …”