CRYSTAL STRUCTURE AND GUEST MOTIONAL BEHAVIOR OF Cd(CN)2 CYCLOHEXANE CLATHRATE. X-RAY DIFFRACTION AND SOLID STATE NMR STUDY. S. Nishikiori*, T. Kitazawa+, C. I. Ratcliffe[[daggerdbl]], J. A. Ripmeester[[daggerdbl]], T. Iwamoto*, *Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, +Department of Chemistry, Toho University, [[daggerdbl]]Steacie Institute for Molecular Sciences, National Research Council of Canada
Cd(CN)2 has Cu2O-like structure, where two diamond-like 3D frameworks based on tetrahedral Cd2+ and bridging CN- are interpenetrated each other. Cd(CN)2*G clathrates were prepared on the idea that one framework in Cd(CN)2 was replaced with bulky organic guest molecules such as cyclohexane, CCl4, etc. X-ray study on Cd(CN)2 cyclohexane clathrate revealed that the host lattice has the diamond-like 3D framework and guest cyclohexane molecule is trapped in empty space of the host lattice. However, two questions remained. One was about ordering of the bridging CN-. X-ray showed orientation of the CN- was in disordered state. However, it has been believed that CN- in Cd(CN)2 is ordered. 113Cd MAS NMR revealed that the CN- was in disordered state in Cd(CN)2*G and even in Cd(CN)2. Another question was about structure and motional behavior of the cyclohexane. X-ray showed only diffuse electron density around the center of the cavity. 2H-NMR powder patterns indicated that the cyclohexane was in rapid random isotropic motion at room temperature and this isotropic motion and the inversion of the cyclohexane ring began to freeze in lower temperature region.