Spin frustration from cis-edge or -corner sharing metal-centered octahedra.

A new strategy using cis-edge or -corner sharing metal-centered octahedra is described which enables interesting frustrated spin lattices to be targeted. The examination of "CuV2" triangular motifs in the two new compounds [enH2]Cu(H2O)2[V2O2F8] (1) and [Cu(H2O)(2,2'-bpy)]2[V2O2F8] (2) (where enH2 = ethylenediammonium and 2,2'-bpy =2,2'-bipyridyl) reveals that the [VOF4](2-) anions, which exhibit cis structure directing properties, lead to frustrated lattices owing to the competing ferro and antiferromagnetic interactions. There is direct coordination through two cis F(-) ligands (i.e., the F(-) ligand trans to O(2-) and one equatorial F(-) ligand) in both 1 and 2 owing to the significant π-bonding between the vanadium and the oxide ligand. We emphasize that most of triangular motifs reported in the literature are built of cis-edge or -corner sharing metal-centered octahedra, thus they can be used to target new materials exhibiting interesting magnetism such as spin frustration.