Photochemistry with Chlorine Trifluoride: Syntheses and Characterization of Difluorooxychloronium(V) Hexafluorido(non)metallates(V), [ClOF2][MF6] (M=V, Nb, Ta, Ru, Os, Ir, P, Sb)

A photochemical route to salts consisting of difluorooxychloronium(V) cations, [ClOF2](+), and hexafluorido(non)metallate(V) anions, [MF6](-) (M=V, Nb, Ta, Ru, Os, Ir, P, Sb) is presented. As starting materials, either metals, oxygen and ClF3 or oxides and ClF3 are used. The prepared compounds were characterized by single-crystal X-ray diffraction and Raman spectroscopy. The crystal structures of [ClOF2][MF6] (M=V, Ru, Os, Ir, P, Sb) are layer structures that are isotypic with the previously reported compound [ClOF2][AsF6], whereas for M=Nb and Ta, similar crystal structures with a different stacking variant of the layers are observed. Additionally, partial or full O/F disorder within the [ClOF2](+) cations of the Nb and Ta compounds occurs. In all compounds reported here, a trigonal pyramidal [ClOF2](+) cation with three additional Cl..F contacts to neighboring [MF6](-) anions is observed, resulting in a pseudo-octahedral coordination sphere around the Cl atom. The Cl-F and Cl-O bond lengths of the [ClOF2](+) cations seem to correlate with the effective ionic radii of the M-V ions. Quantum-chemical, solid-state calculations well reproduce the experimental Raman spectra and show, as do quantum-chemical gas phase calculations, that the secondary Cl...F interactions are ionic in nature. However, both solid-state and gas-phase quantum-chemical calculations fail to reproduce the increases in the Cl-O bond lengths with increasing effective ionic radius of M in [MF6](-) and the Cl-O Raman shifts also do not generally follow this trend.

Automated summary

A photochemical route was used to synthesize salts consisting of [ClOF2](+) cations and [MF6](-) anions (M=V, Nb, Ta, Ru, Os, Ir, P, Sb). The compounds were characterized using single-crystal X-ray diffraction and Raman spectroscopy, revealing similar crystal structures for some compounds. Quantum-chemical calculations were able to reproduce the experimental Raman spectra, showing that the secondary Cl...F interactions are ionic in nature. However, the calculations failed to explain the increases in Cl-O bond lengths with increasing effective ionic radius of M in [MF6](-) and the Cl-O Raman shifts did not always follow this trend.