STRUCTURES AND LIBRATIONAL MOTIONS OF P-DICHLOROBENZENE IN WERNER CLATHRATES

Two structures of the Ni(SCN)2(4-EtPy)4 Werner clathrate (4-EtPy = 4-e thylpyridine) and one structure of Ni(SCN)2(4-AcPy)4 clathrate (4-AcPy = 4-acetylpyridine) with p-dichlorobenzene (PDCB) as a guest molecule have been elucidated. The host molecules have the usual octahedral '' propeller'' conformations and form channel-type cavities. Effective li brational frequencies of the PDCB molecule in these clathrates, and in 14 other Werner clathrates, have been determined from the temperature dependence of the Cl-35 nuclear quadrupole resonance (NQR) frequencie s.