Hydrothermal chemistry of oligomeric vanadium oxyfluorides

Abstract

Nine new vanadium oxyfluorides, containing ten different oligomeric vanadium (oxy)fluoride anions have been prepared by solvothermal synthesis in water-ethylene glycol and using organic cations as co-crystallising agents. Crystal structures are reported for each. Amongst the ten structure types, five represent previously unobserved moieties, including one monomeric unit (cis-[VOF4(H2O)]2-), two dimers ([V2O2F6(H2O)2]2- and [V2O2F8]4-) and two tetramers (both isomers of composition [V4O4F14]6-). Structural relationships between the various units are discussed, together with some rationalisation of their occurrence as a function of synthetic variables.

Syntheses and Physicochemical Properties of Low‐Melting Salts Based on VOF4– and MoOF5–, and the Molecular Geometries of the Dimeric (VOF4–)2 and Mo2O4F62– Anions

“…The total bond valence for the vanadium(IV) atom in V 2 O 2 F 8 4-is 3.96. [15] Therefore, both the vanadium atoms in the VOF 4 -and V 2 O 2 F 8 4-anions are consistent with their oxidation states, whereas the difference in the bridging forms probably arises from the more crowded coordination environment around the vanadium atom at the oxidation state of five. The anions in EMImVOF 4 behave like a doubly charged anion in EMImVOF 4 , which probably results in the relatively high melting point of EMImVOF 4 .…”

“…[4][5][6] Vanadium gives a variety of oxofluoroanions at different oxidation states, which have potential applications in catalytic and medicinal chemistry, [7][8][9][10] including V IV OF 3 -, [11] V IV OF 4 2-(OH 2 ), [12][13][14] V IV 2 O 2 -F 8 4-, [15,16] V IV OF 5 3-, [17] V V OF 4 -, [18][19][20] V V OF 5 2-, [21] V V O 2 F 3 2-, [22] and V V 2 O 4 F 5 3-. [23] A recent spectroscopic study combined with a DFT calculation characterized the monomeric VOF 4 -anion in its tetramethylammonium salt, [20] whereas the VOF 4 -anion determined in CsVOF 4 has a secondary contact from a neighboring anion, resulting in a chain-like anionic unit.…”

A hybrid vanadium fluoride with structurally isolated S = 1 kagome layers

“…This study forms part of our ongoing efforts to explore and understand the complex solvothermal/ionothermal chemistry of vanadium fluoride-based systems 8,[19][20][21] . Specifically, compound 1 was isolated by using identical chemistry ¶ to that in the preparation of the QSL compound DQ-VOF, except that the temperature of the reaction was increased from 170 to 210 C and the time was increased from 1 day to 5 days.…”

Synthesis, crystal and electronic structure, and theoretical investigations of charge-transfer, optical, and bonding properties of a [VF6]3− anion compound

“…However, to our knowledge, the [VF 6 ] 3-species in 1 is the first structure with perfect centrosymmetric octahedron characterized by X-ray technique so far, though some acentric [VF 6 ] 3-species have been reported owing to distortion [13,14]. It is worthwhile to look into the geometric structure, electronic structure, charge-transfer properties, optical properties, and bonding property of the [VF 6 ] 3-anion at the levels of density functional theory (DFT) [15,16] and time-dependent density functional theory (TDDFT) [17,18].…”