Novel vanadium(IV) oxyfluorides with 'spin-ladder'-like structures, and their relationship to (VO)2P2O7.

Three novel vanadium(IV) oxyfluorides have been prepared by hydrothermal synthesis. All three materials feature 'ladder'-like chains of edge- and corner-sharing V(O/F) octahedra, topologically similar to those in (VO)2P2O7. CsVOF3 and RbVOF3 are isostructural, whereas in (bpeH2)1/2[VOF3] (bpe = trans-1,2-bis(4-pyridyl)-ethylene) inclusion of the organic structure-directing agent affects both the conformation of the ladders and their packing within the unit cell. Magnetic susceptibility data for each of the new materials have been fitted using a spin-1/2 Heisenberg antiferromagnetic chain model, which shows that the predominant magnetic interactions act along the 'legs' of the ladder, with negligible interactions both along the 'rungs' and between neighboring chains. This behavior contrasts markedly with that of (VO)2P2O7 itself.