Discovery of Heteropolytantalate: Synthesis and Structure of Two 6-Peroxotantalo-4-phosphate Clusters

Abstract

Polyoxometalates (POMs) of Nb and Ta are greatly different from those of Mo, W, and V that have been studied extensively and developed well. The latter can be formed simply by acidification of their aqueous monomeric oxoanions and has found application areas from catalysis to magnetism, materials science, medicine, and nanotechnology. Even now the polyoxoniobate (PONb) chemistry has accelerated dramatically over the last 15 years, and a vast expansion of available PONbs has been reported. However, after nearly 200 years of POM research, Ta-based POM chemistry is still at its infant stage and only dominated by the isopolyoxotantalate ions (Ta and Ta) and transition-metal-capped Ta species, along with two Ti-substituted polyoxotantalates [TiTaO] and [TiTaO] reported very recently. In this study, we discover two novel peroxotantalophosphate clusters [P(TaO)O] (1) and [P(TaO)O] (2) by incorporating phosphorus heteroatom into Ta-oxo framework, which represent the first two examples of heteropolytantalate. Interestingly, two PTa half-units are cis- and trans-condensed in 1 and 2, leading to "open" and "closed" configurations, respectively. These two chemically and structurally related clusters can be isolated in a controlled manner, and the yields are relatively high. Both compounds were characterized in the solid state by single-crystal X-ray diffraction, P MAS NMR, FT-IR, TGA, and elemental analysis as well as byP NMR in solution. The results presented here provide a strategy to be applicable to other heteroatom-incorporated polyoxotantalates and further expand the phase space for polyoxotantalate chemistry.

A Nonclassical Polyoxoanion [P3W6(O2)6(OH)2O22]7– Constructed by Two {PW3(O2)3(OH)O9} Subunits and a {PO4} Group

“…From the viewpoint of structure, the P 2 W 3 subunit in P 3 W 6 cluster resembles P 2 M 3 subunit in [P 4 M 6 (O 2 ) 6 O 24 ] 12– ( P 4 M 6 , M = Nb/Ta) species recently reported by Casey and us , , . One remarkable difference among them is that P 3 W 6 can be regarded as two P 2 W 3 units fused by sharing a {PO 4 } group in a head‐to‐head way (Figure ), while the two P 2 M 3 subunits in P 4 M 6 are connected by four oxygen atoms.…”

“…Subsequently, we reported a series of peroxo‐containing heteropolyoxoniobates {As 2 Nb 4 (O 2 ) 4 O 14 }, {P 4 Nb 6 (O 2 ) 6 O 24 } and its transition metal derivatives . In 2017, the first two peroxo‐containing heteropolyoxotantalates {P 4 Ta 6 (O 2 ) 6 O 25 } and {P 4 Ta 6 (O 2 ) 6 O 24 } were communicated by our groups . Therefore, enormous efforts have been made in order to explore the new analogue structures based on peroxo‐containing heteropolyoxotungstate.…”

Polyoxometalates: Tailoring metal oxides in molecular dimension toward energy applications

“…43,349,[353][354][355][356][357][358][359] A number of other transition metalbased polyoxometalates have been investigated, such as silver-containing polyoxometalates, 226,[360][361][362][363][364][365] zinccontaining polyoxometalates. 366 polyoxotantalate, [367][368][369][370][371][372][373][374][375][376][377][378][379][380][381][382][383][384] ruthenium-containing polyoxometalates, [385][386][387] coppercontaining polyoxometalates, [388][389][390] chromium-containing polyoxometalates, 391 and polyoxoaurates [392][393][394][395] ; their real applications to substitute their metal oxides counterparts deserve further exploration.…”

“…A number of other transition metal‐based polyoxometalates have been investigated, such as silver‐containing polyoxometalates, zinc‐containing polyoxometalates . polyoxotantalate, ruthenium‐containing polyoxometalates, copper‐containing polyoxometalates, chromium‐containing polyoxometalates, and polyoxoaurates; their real applications to substitute their metal oxides counterparts deserve further exploration.…”

Photocatalytic decolorization of three commercial dyes using a new heteropolyoxotantalate catalyst

“…In 2016, Son & Casey [28] communicated two Ti-substituted POTa clusters, [Ti 2 Ta 8 O 28 ] 8− and [Ti 12 Ta 6 O 44 ] 10− . Very recently, Niu and co-workers [29] reported two 6-Peroxotantalo-4-phosphate clusters, from the viewpoint of structure, which can be regarded as the first two examples of hetero-POTas (HPOTas).…”