1. N. Tokitoh, Y. Arai, R. Okazaki, Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113, Japan.
2. S. Nagase, Department of Chemistry, Faculty of Science, Tokyo Metropolitan University, 1-1 Minami-osawa, Hachioji, Tokyo 192-03, Japan.