An ionothermally prepared S = 1/2 vanadium oxyfluoride kagome lattice.

Frustrated magnetic lattices offer the possibility of many exotic ground states that are of great fundamental importance. Of particular significance is the hunt for frustrated spin-1/2 networks as candidates for quantum spin liquids, which would have exciting and unusual magnetic properties at low temperatures. The few reported candidate materials have all been based on d(9) ions. Here, we report the ionothermal synthesis of [NH(4)](2)[C(7)H(14)N][V(7)O(6)F(18)], an inorganic-organic hybrid solid that contains a S = 1/2 kagome network of d(1) V(4+) ions. The compound exhibits a high degree of magnetic frustration, with significant antiferromagnetic interactions but no long-range magnetic order or spin-freezing above 2 K, and appears to be an excellent candidate for realizing a quantum spin liquid ground state in a spin-1/2 kagome network.

Increasing the dimensionality of hybrid vanadium oxyfluorides using ionothermal synthesis.

A unique organically-templated vanadium(IV) oxyfluoride, [pyH][V(2)O(2)F(5)] has been prepared using an ionothermal approach. This compound has a novel layered structure which may be considered as arising via condensation of previously known 'ladder-like' structural building units. This suggests that ionothermal synthesis may provide a more effective route to extended network structures in these systems than the more widely explored hydrothermal-based media.

A new approach to synthesis of layered fluorites containing molecular anions: synthesis of Ln2O2CO3, K(LnO)CO3, and Ln2O2CrO4 via metathesis reactions.

A new synthetic approach is suggested for preparation of layered rare-earth oxide compounds containing [Ln2O2] slices and molecular anion sheets (CO32-, SO42-, and CrO42-). It is based on exchange reactions of rare-earth oxychlorides, [Ln2O2]Cl2, and alkali carbonates, sulfates, or chromates. Five new rare-earth oxychromates [Ln2O2]CrO4 (Ln=Pr-Gd) have been prepared which adopt a new, probably layered, structure type. In addition, significantly easier and more efficient synthetic pathways were found to the known compounds [Ln2O2]K2(CO3)2 and [La2O2]CrO4. The structure of the latter compound has been determined from neutron powder diffraction data. Factors affecting reaction pathways and products are discussed, as well as prospects for applying the approach to more complex layered compounds.

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.