1. Department of Chemistry, University of Rochester, Rochester, New York 14627
2. Department of Chemistry, Princeton University, Princeton, New Jersey 08544
3. The Graduate University for Advanced Studies, Myodaiji, Okazaki 444, Japan
4. Institute for Molecular Science, Myodaiji, Okazaki 444, Japan
5. Institut de Chimie Physique, Ecole Polytechnique Fédérale, CH-1015 Lausanne, Switzerland