Bis(4-aminopyridinium) μ₆-oxido-dodeca-μ₂-oxido-hexaoxido[rhenium(VII)tetratungsten(VI)vanadium(V)]ate heptahydrate

Abstract

In the title organic–inorganic hybrid compound, (C5H7N2)2[ReVW4O19]·7H2O, the Lindqvist-type polyoxido anion has crystallographically imposed mm2 symmetry and is built up by six MO6 (M = W, V, Re) edge-sharing distorted octa­hedra. The Re and V atoms share the same crystallographic site in a 0.5:0.5 ratio. The 4-amino­pyridinium cations lie on a mirror plane. Three of the four independent water O atoms in the asymmetric unit are located on a mirror plane whereas the remaining O atom has mm2 site symmetry. In the crystal, the cations, anions and water mol­ecules are linked into a three-dimensional network through O—H⋯O and N—H⋯O hydrogen-bonding inter­actions.

Aldehyde-Assisted Aerobic-Oxidative Desulfurization of HDS Diesel Fuels by a Highly Effective Heterogeneous V-Substituted Keggin-Type Semiorganic Catalyst: Modeling of Experimental Design and Mechanistic and Kinetic Insights

“…The solid-state UV–vis electronic spectra of (AP) 5 PWV 2 and AP are shown in Figure S1. As previously reported, the characteristic bands of Keggin polyanion are shown between 200 and 550 nm, corresponding to MO t (208–232 nm) and M–O b/c –M (238–555 nm) electron charge transfer. , The band in the region of higher energy centered at 213 nm is assigned to the charge transfer from terminal O 2p to M 5d (O t → M), whereas the bands observed in the lower energy region at 289 and 379 nm are assigned to the charge transfer from bridging O 2p to M 5d (O b/c → M, M = W/V). , The remaining band at 260 nm may be due to n → π* transition of 2-aminopyridinium cations in accordance with the UV–vis spectrum of free AP (Figure S1). The excitation at λ ex = 370 nm of the (AP) 5 PWV 2 solid revealed an important red luminescence, with maximum emission detected at 630 nm in the emission spectrum (Figure S1).…”

“…32,33 As shown in figure S3, the (AP) 5 PWV 2 catalyst showed XRD diffraction peaks at the 2θ values between 5 and 10°c haracteristic of the Keggin type structure. 32,33 It should be noted that these peaks are slightly different from those ascribed to the H 3 PW 12 O 40 parent Keggin-type heteropolyacid (JCPDS File 00−050−0655) due to the replacement of H + protons by 2-aminopyridinium organic cations (AP + ). Single-crystal XRD analysis revealed that the asymmetric unit of (AP) 5 PWV 2 is built up from five 2-aminopyridinium cations (AP), half of pyridine-amine, two water crystallizations, and one Keggin-type polyanion [PV 2 W 10 O 40 ] 5− (Figure 3a), where the phosphor heteroatom occupies the central tetrahedron, whereas two vanadium and ten tungsten ions are disordered over the whole heteropolyanion [PM 12 O 40 ] n− , where each metal M (with M = W/V) site was assigned as 10/ 12 W and 2/12 V. This later is iso-structural with the common polyanion [PW 12 O 40 ] 4− , the so-called Keggin-type polyoxotungstate described as a shell of {M 12 O 36 } (M = W/V) encapsulating a PO 4 central tetrahedron corner-sharing fourtriad {M 3 O 9 } cluster (Figure 3b).…”

“…30,31 As shown in the packing diagram (Figure 3c), Keggin clusters and organic cations assemble into a 3D host network stabilized with a strong set of various hydrogen bonding and van der Waals interactions. The independentbased pyridinium moieties reside in the channel voids, 31,32 The band in the region of higher energy centered at 213 nm is assigned to the charge transfer from terminal O 2p to M 5d (O t → M), whereas the bands observed in the lower energy region at 289 and 379 nm are assigned to the charge transfer from bridging O 2p to M 5d (O b/c → M, M = W/V). 33,34 The remaining band at 260 nm may be due to n → π* transition of 2-aminopyridinium cations in accordance with the UV−vis spectrum of free AP (Figure S1).…”

Combined Experimental and Computational Study of V-Substituted Lindqvist Polyoxotungstate: Screening by Docking for Potential Antidiabetic Activity

“…Nowadays, the synergistic effect of mixed metal facilitates the close surfaces to powerfully connect with other species, especially, transition metal complexes and organic cations, being potent materials with a set of scientific patent and functional claims in optical, electrical, and biological fields, − namely, two wide-band gap semiconductors (H2pip) 2 [V 2 W 4 O 19 ]·4H 2 O ( E g = 3.92 eV) and (H2pipEtOH) 2 [V 2 W 4 O 19 ]·4H 2 O ( E g = 3.72 eV), which are previously reported and specified by their promising antibacterial and antifungal activities as well as their higher dielectric constants …”

Intramolecular Re···O Nonvalent Interactions as a Stabilizer of the Polyoxorhenate(VII)

“…The structure of the [Re 4 O 15 ] 2– anion under consideration is the first registered polyoxometalate cluster of the manganese subgroup containing all metal atoms in only the highest oxidation state (+7). The only known polyoxotechnetate contains both Tc­(VII) and Tc­(V). , Previously, rhenium could be incorporated into POM but only as a heteroatom and mainly in reduced forms. − The polyoxorhenate synthesized in our work is the first representative not only of a new class of rhenium compounds but also of a new type of the polyoxometalates for the elements of the seventh group of the periodic table. Due to chemical features, perrhenates and pertechnetates usually (in the vast majority of cases, with rare exceptions ,− ) are tetrahedral anions, and an octahedral oxygen environment is not typical for M­(VII) n − anions.…”