1. a State Key Laboratory of Structural Chemistry , Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences , Fuzhou , 350002 , P.R. , China
2. b Department of Chemistry , Chinese University of Hong Kong , New Territories , Hong Kong
3. c Laboratory of Rare Earth Chemistry and Physics , Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun , 130022 , P. R. , China