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.