1. Department of Chemistry, Royal Institute of Technology (KTH), SE-100 44 Stockholm, Sweden, Department of Structural Chemistry, Arrhenius Laboratory, University of Stockholm, SE-106 91 Stockholm, Sweden, Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninsky Prospect 31, Moscow 117907, Russia, Department of Chemistry, Stanford University, Stanford, California 94305-5080, and Department of Chemistry, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden