1. Department of Chemistry, Michigan State University, East Lansing, Michigan 48823, I.M.N., UMR CNRS C6502, Institut des Materiaux Jean Rouxel, Laboratoire de Chimie des Solides, 2 rue de la Houssiniere, BP 32229, 44322 Nantes Cedex 03, France, Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 180 40 Praha 8, Czech Republic, and Department of Chemistry, Northwestern University, Evanston, Illinois 60208