The dimeric [V2O2F8]4− anion: Structural characterization of a magnetic basic-building-unit

New materials built from the [V2O2F8]4− anionic basic-building-unit (BBU) exhibit interesting magnetic properties owing to the proximity of the two d1 V(IV) cations and the orbital interactions of fluoride and oxide ligands. In our search to target such materials, the vanadium oxide–fluoride compound [dpaH2]2[V2O2F8] in which a dimeric anion [V2O2F8]4− is isolated in a hydrogen bond network was hydrothermally synthesized (dpa=2,2′-dipyridylamine). This hydrogen bond network is able to stabilize the highly ionic species [V2O2F8]4− as demonstrated with bond valence calculations. The coordination of the O2−/F− ordered ligands was investigated and antiferromagnetic coupling of the isolated BBU was measured.