1. Department
of Chemistry, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
2. JST, ERATO Isobe Degenerate π-Integration Project, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
3. Advanced
Institute for Materials Research, Tohoku University, Aoba-ku, Sendai 980-8577, Japan