1. Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vass. Constantinou Ave., Athens 116 35, Greece
2. Department of Chemistry, Konan University, 8-9-1 Okamoto, Higashinada-ku, Kobe 658, Japan
3. College of Engineering, Osaka Prefecture University, 1-1 Gakuen-chu, Sakai, Osaka 593, Japan