Novel binuclear vanadium(V)–Schiff base cations containing single fluorine bridges and the structure of difluorodioxovanadate(1–)

Abstract

The complex [VO (salen)][H₂salen =N,N′-ethylenebis(salicylideneimine)] reacted with HBF₄·Et₂O in air to produce the novel linear species [{VO (salen)}₂(µ-F)]⁺, the structure of which has been determined as its BF₄^– and [VO₂F₂]^– salts. The perchlorate and triflate (O₃SCF₃)^– salts have been characterised spectroscopically and analytically, as well as the tetrafluoroborate homologues from salicylaldehyde and 2-methylpropylenediamine, and from ethylenediamine and 3-methoxysalicylaldehyde. The [VO₂F₂]^– is mononuclear in the above salt, as well as in [PPh₄][VO₂F₂], compared to a polynuclear form found in [NH₄][VO₂F₂]. The mononuclear anion was also fully characterised by ¹⁹F and ⁵¹V NMR spectroscopy.