Giant metal-oxide-based spheres and their topology: from pentagonal building blocks to keplerates and unusual spin systems

Novel synthesis strategies based on the geometrical and topological princip les outlined here open up pathways to a new class of spherical clusters wit h icosahedral symmetry of the type (pentagon)(12)(linker)(30)- also called keplerates -where the centers of the 12 pentagons span an icosahedron and t he centers of the 30 linkers an icosidodecahedron. Remarkably, sizing of a spherical molecule is possible for the first time. In addition to their lar ge size of several nanometers, these molecules show unusually high symmetri es. When large numbers of paramagnetic metal centers like 30 Fe-III or 20 V O2+ are integrated within their structure, extraordinary spin topologies ca n be realized on a discrete molecular level. Further functionalization of t hese systems allows, e.g. to link them forming chains or layers in solid st ate reactions at room temperature. (C) 2001 Elsevier Science B.V. All right s reserved.