1. Key Lab of Inorganic Synthesis and Preparative Chemistry, Department of Chemistry, Jilin University, Changchun 130023, P. R. China, Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo, Hongo, Tokyo 113-0033, Japan, CREST, Japanese Science and Technology Corporation, Japan, and Department of Physics, Tohoku University, Sendai 980-8578, Japan