Small, beautiful and magnetically exotic: {V4W2}- and {V4W4}-type polyoxometalates

Abstract

Minimal-nuclearity vanadato-tungstate clusters in [{VIV(dien)}4WVI2O14]·4H2O (1) and [{VIV(dien)}4WVI4O20]·6H2O (2) feature cores of edge-sharing WO6 octahedra, surrounded by a ring of four vanadyl groups. Surprisingly, the V(iv) centers in both 1 and 2 are ferromagnetically coupled, in contrast to all other known vanadato-polyoxotungstates featuring the ubiquituos V-O-W-O-V exchange pathways.