Synthesis and Characterization of the Face-Sharing Bioctahedral [Mo₂O₆F₃]^3- Anion

Abstract

The face-sharing bioctahedral molybdenum(VI) oxide fluoride anion [Mo2O6F3]3- has been isolated in the new compound [Cu(3-apy)4]3(Mo2O6F3)2 (3-apy = 3-aminopyridine) and has been characterized by experimental and computational techniques. Single-crystal X-ray diffraction studies show that the structure of the [Mo2O6F3]3- anion resembles two distorted face-sharing octahedra, each with three short terminal metal-ligand bonds and three long metal-ligand-metal bridging interactions. Aspects of the electronic structure, as well as geometric comparisons of the bond lengths and angles in [Mo2O6F3]3- with those in the similarly distorted [MoO3F3]3- anion, suggest that the six terminal ligand positions of the confacial bioctahedra are occupied exclusively by oxide ligands and that the three bridging sites are occupied by fluorides. Crystal data for [Cu(3-apy)4]3(Mo2O6F3)2: trigonal space group R3 (No. 148) with hexagonal axes of a = 13.881(1) A and c = 31.783(3) A (Z = 3).

The Dimeric [V2O4F6]4– Vanadium Oxide‐Fluoride Anion in Na2(M(H2O)2)(V2O4F6) (M = Co2+, Ni2+, and Cu2+)

“…We have previously described the placement of fluoride anions within bridging positions of two ETMs within the ordered [Mo 2 O 6 F 3 ] 3– dimeric BBU. The position of oxide anions in terminal (non‐bridging) positions of the VOF BBU allows greater stability owing to greater π‐overlap between V 5+ and O 2– 16. Additionally, the two vanadium(V) cations, shown in Figure 1, repel each other to result in elongated, bridgingV–F bonds.…”

Hexagonal Perovskites as Quantum Materials

“…those of the purely oxide hexagonal perovskites. Their potential applications as photocatalysts and cathode materials have, however, recently been investigated [183][184][185][186][187][188] . When materials physicists figure out that some of them can be grown as nice single crystals, then more detailed studies can be expected.…”

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

“…Whereas the C7-C8-C9-C10 angle [178.87(17)°] adopts a nearly anti conformation, the N1-C7-C8-C9 torsion angle is -63.8(2)°because of the effect of crystal packing. In the Mo 2 O 4 F 6 2-anion, the four Mo-F bridging bond lengths are nearly the same [2.1691 (12) [29] Another example of molybdenum complex anion containing Mo-F-Mo is Mo V 2 O 2 F 9 3-, where the Mo-F bridging bonds range from 2.118(2) to 2.19(2) Å. [25] The terminal Mo-F [1.9083 (13) Figure 6.…”

“…[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. [19] Molybdenum also forms oxofluoro complex anions in diverse coordination states including Mo V OF 5 2-, [24,25] Mo V 2 O 2 F 9 3-, [25] Mo VI -OF 5 -, [26,27] Mo VI O 2 F 4 2-, [28] Mo VI 2 O 6 F 3 3-, [25,29] and Mo VI 4 -O 12 F 2 2-, [30] where some of the anions provide interesting structures with unique bridging states. Molecular units structurally related to these anions were also reported.…”