[V30Mo72]: Quantum Keplerate

[V<sub>30</sub>Mo<sub>72</sub>] Adding vanadyl sulfate to an acidified molybdate solution, in presence of K+ cations, results in formation of the compound abbreviated as [V30Mo72]. The vanadyl ions form a slightly distorted icosadodecahedron. This fascinating, highly symmetric structure is a spherical arrangement of pentagons and triangles. The S = 1/2 vanadyl ions are strongly exchange coupled. Quantum Monte Carlo simulations show that the average interaction is around J = 245 K. Strong exchange interactions between vanadyl ions despite long exchange pathways is a phenomenon that has been found in other vanadyl polyoxomolybdates. It is much stronger than the exchange interaction in [Fe30Mo72]. The higher spin of the iron ions (S = 5/2) compared to vanadium allowed the application of various classical calculation methods in that case. In that sense [V30Mo72] can be compared as the quantum analogue of [Fe30Mo72]

Figure: (top) Combined polyhedral and ball-and-stick representation of the structure of [V30Mo72], showing the triangles and pentagons of the icosidodecahedron, and additionally the basic {VO5} and {VO6} units as green polyhedra; (Mo atoms blue, O atoms red, K atoms purple, and SO42- groups yellow tetrahedra, disordered S atoms yellow).

A. Müller, A.M. Todea, M. Dressel, J. van Slageren, H. Bögge, M. Schmidtmann, M. Luban, L. Engelhardt, M. Rusu On Triangular Geometrical and Magnetic Motifs Uniquely Linked on a Spherical Capsule-Surface, Angew. Chem. Int. Ed. 44 (2005) 3857 - 3861