1. Contribution from the Department of Chemistry, Faculty of Science, Kumamoto University, Kurokami 2-39-1, Kumamoto 860-8555, Japan, Department of Chemistry, Faculty of Education and Welfare Science, Oita University, Dan-noharu 700, Oita 870-1192, Japan, and Department of Chemistry, Faculty of Science, Okayama University, Tsushima-naka 3-1-1, Okayama 700-8530, Japan