1. Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Bunkyo-ku 113-0033, Japan
2. R&D Department of Chemicals, Nippon Light Metal Company, Ltd., Shimizu-ku, Shizuoka 421-3203, Japan
3. Cluster for Pioneering Research (CPR), Advanced Elements Chemistry Laboratory, RIKEN, Wako, Saitama 351-0198, Japan