Structural and Spectroscopic Evidence for the Formation of Trinuclear and Tetranuclear Vanadium(III)/Carboxylate Complexes of Acetate and Related Derivatives in Aqueous Solution

Successive constructions of regular tetra-, hexa- and octanuclear microporous polyoxovanadates(III) for gas adsorption

Pyrazole-assisted tetranuclear microporous polyoxovanadates(III) (POVs) (NH₄)₂K₂[V₄(μ₂-OH)₄(ox)₄(pz)₄]·9H₂O (1, ox = oxalate and pz = pyrazole) and (NH₄)₂Na₂[V₄(μ₂-OH)₄(ox)₄(4-mpz)₄]·7H₂O (2, 4-mpz = 4-methylpyrazole) have been constructed in reduced media, along with their triazole neutral hexa- and octanuclear products K₂[V₆(μ₂-OH)₆(ox)₆(Hdatrz)₆]Cl₂·29.5H₂O (3) and [V₈(μ₂-OH)₈(SO₃)₈(Hdatrz)₈]·38H₂O (4, Hdatrz = 1H-1,2,4-triazole-3,5-diamine) successively. Both polyanionic structures of 1 and 2 share similar inorganic building blocks that consist of regular {V₄(μ₂-OH)₄} skeletons with an inner diameter of 2.8 Å, while a paddle wheel-shaped cluster 3 contains a {V₆(μ₂-OH)₆} skeleton with two chlorides encapsulated around the center of the ring, occupying a hole of 3.7 Å. An interesting isolated intrinsic polyoxometalate-based metal-organic framework (POMOF) 4 exists as an octanuclear petaloid-like skeleton {V₈(μ₂-OH)₈(SO₃)₈} with an inner diameter of 5.2 Å. Bond valence sum calculations manifest that all V ions have severely reduced +3 oxidation states in 1-4, which are supported by charge balance, structural and magnetic data. Moreover, gas adsorptions indicate that 1, 2 and 4 can adsorb CO₂ and O₂ more favorably than N₂, CH₄ and H₂ gases. Compared with 1 and 2, due to the functionalization of microchannels with Lewis base amino and hydroxy groups and uncoordinated azolate N-donors inside POMOF 4, it should have notable affinities toward CO₂ adsorption.

The rare example of hybrid chalcogenoarsenates(III) incorporating trivalent vanadium complexes

A series of new hybrid vanadium chalcogenoarsenates(III) [VIII(en)2AsIIIS3] (1, en = ethylenediamine), [VIII(dap)2AsIIISe3] (2, dap = 1,2-diaminopropane), [VIII(teta)AsIIIQ3] {Q = S (3), Se (4), teta = triethylene-tetramine}, and [VIII2(en)6(μ2-O)][As2Se5] (5)...

Organo-functionalized polyoxovanadates: crystal architecture and property aspects

Polyoxovanadates (POVs), as one of the most prominent members of polyoxometalates (POMs), have been subject to extensive studies by virtue of their aesthetically intriguing structures and potential applications in catalysis, magnetism, and optics, among others. In recent years, organo-functionalized POVs have received considerable attention due to the combination of the advantages of POVs with the importance of organic species. In this review, the key developments of polyoxovanadates and, particularly, the achievements that are related to polyoxovanadates modified with organic ligands and transition metal-organic ligand are summarized. Herein, we systematically introduce the structural features of organo-functionalized POVs and their main applications involved in the magnetism and catalysis aspects. Finally, the current challenges and future prospects in the design, synthesis, and property investigation of polyoxovanadates are also discussed.

One-Dimensional Vanadium(III) Chalcogenidostannates Incorporating [V(tepa)]3+ Complexes as Bridging Groups

Two new one-dimensional (1D) vanadium(III) chalcogenidostannates, [H₂tepa]_0.5n[V^III(tepa)(μ-Sn₂Q₆)]_n [Q = S (1), Se (2); tepa = tetraethylenepentamine], were achieved by solvothermal methods, which offer the first examples of organic hybrid polymeric chalcogenidostannates incorporating [V(tepa)]³⁺ complexes as bridging groups. Both 1 and 2 feature the 1D sinusoidal chains of [V^III(tepa)(μ-Sn₂Q₆)]_n containing two types of novel bridging modes of the [μ-Sn₂Q₆]^4- anion. Their magnetic, photocurrent response, and optical properties are also studied.

A series of new hybrid chalcogenogermanates: the rare examples of chalcogenogermanates combined with trivalent vanadium complexes

A series of new hybrid chalcogenogermanates [Mn₂(en)₄Ge₂S₆]_n (1, en = ethylenediamine), [Mn₂(dap)₄Ge₂S₆]_n (2, dap = 1,2-diaminopropane), [H₂dien]_n[MnGeS₄]_n (3, dien = diethylenetriamine), [V(en)₂(ea)]₂[Ge₂Se₆] (4, Hea = ethanolamine), [V(teta)(ea)]₂[Ge₂Se₆] (5, teta = triethylenetetramine) and [V₂(en)₆(μ-O)][Ge₂Se₆] (6) were solvothermally synthesized and structurally characterized. Both 1 and 2 contain dimeric [Ge₂S₆]^4- anions and [Mn(en)₂]²⁺/[Mn(dap)₂]²⁺ complex cations, which are interconnected to generate 1-D neutral chain-like structures [Mn₂(en)₄Ge₂S₆]_n and [Mn₂(dap)₄Ge₂S₆]_n, respectively. 3 consists of a protonated H₂dien²⁺ cation and a 1-D straight chain built from [MnS₄] and [GeS₄] tetrahedra sharing opposite edges, and is the only example of a chelating amine uncoordinated to a transition metal ion. Both 4 and 5 consist of [Ge₂Se₆]^4- anions constructed by two [GeSe₄] tetrahedra sharing a common edge and discrete complex cations [V(en)₂(ea)]²⁺/[V(teta)(ea)]²⁺. 6 is composed of a [Ge₂Se₆]^4- anion and dinuclear complex cation [V₂(en)₆(μ-O)]⁴⁺ containing an en molecule as a rare monodentate ligand. Although some selenidogermanates with transition metal complexes have been successfully prepared, no selenidogermanates with trivalent vanadium complexes have been documented. Therefore, 4-6 offer the first examples of selenidogermanates with trivalent vanadium complexes under solvothermal conditions. Their optical and photocurrent response properties were studied.

A series of new vanadium(iii) chalcogenido-antimonates: an unusual seven-coordinate nitro-selenidovanadium(iii) complex

A series of new vanadium(iii) chalcogenidoantimonates [VIII(dap)2SbQ3] (Q = S (1), Se (2); dap = 1,2-diaminopropane), [H2dien][VIII2(en)2(dien)2(μ2-O)][SbSe4]2 (3, en = ethylenediamine; dien = diethylenetriamine) and [VIII(dien)2SbSe4] (4) have been solvothermally synthesized and structurally characterized. Both 1 and 2 contain neutral vanadium(iii)-centered complexes [VIII(dap)2SbQ3], where the [SbQ3]3- anion acts as a chelating ligand to complex [VIII(dap)2]3+, but they exhibit different molecular conformations. 3 consists of selenidoantimonate anions [SbSe4]3-, the protonated H2dien2+ cation, and the dinuclear complex [VIII2(en)2(dien)2(μ2-O)]4+ based on two [VIII(en)(dien)]3+ units bridged by one μ2-O group. 4 contains neutral [VIII(dien)2SbSe4] moieties with seven coordinated vanadium centres, which offers a rare example of high coordination of a nitro-selenidovanadium(iii) complex, mainly because the vanadium(iii) ion has a regular octahedral configuration based on the structures in the solid state. The optical, magnetic and photoelectronic properties of all compounds have been investigated, and the density functional theory calculation of 4 has also been studied.

Synthesis, structures, and magnetic properties of metal-organic polyhedra based on unprecedented {V7} isopolyoxometalate clusters

Two isostructural vanadium-based metal-organic polyhedra (denoted as VMOP-16 and VMOP-17) were synthesized by a solvothermal method, which are built from unprecedented {V₇} isopolyoxometalate clusters and dicarboxylate ligands. To our knowledge, the {V₇} second building unit is reported for the first time and features the highest nuclearity of vanadium-oxygen clusters compared with reported vanadium-based MOPs.

Polyoxovanadate-based organic-inorganic hybrids: from {V5O9Cl} clusters to nanosized octahedral cages

Three polyoxovanadate-based metal-organic polyhedra (denoted as VMOP-1, -2, and -3), adopting isostructural discrete octahedral cage geometries, were successfully synthesized under solvothermal conditions. These structures are all built up from the same pentavanadate {V5O9Cl} cluster connected by linear bidentate ligands (H2L1 = H2BDC, H2L2 = H2BDC-NH2, H2L3 = H2BDC-Br), respectively.