VIBRATIONAL-SPECTRA OF PARTIALLY DEBENZENATED ANALOGS IN SOME EN-T-D-TYPE CLATHRATES

The en-Td-type clathrates are host-guest compounds with the general fo rmula M(en)M'(CN)(4) . 2G; M is octahedrally coordinated metal, M' is tetrahedrally coordinated metal (Hg, Cd or Zn) and G is a guest molecu le (in our case benzene). The influence of a gradual loss of the benze ne molecules from the host lattice in these partially debenzenated cla thrates was studied by infrared spectroscopy. For this purpose, a seri es of partially debenzenated en-T-d-type clathrates was prepared and t heir infrared spectra recorded. The loss of the benzene from the host lattice did not cause any changes in the frequency of the bands due to the vibrations of the benzene molecules. However, considerable change s in the bands due to the vibrations of the host lattice, M(en)M'(CN)( 4), were detected. These changes are most evident in the region of the stretching and out-of-plane bending NH2 vibrations. Most of the bands due to these vibrations are no longer present in the vibrational spec tra of the ''empty clathrates'' (clathrates in which the benzene has l eft the host lattice). One explanation for this behaviour could be the existence of an interaction between the guest molecules and the host lattice. (C) 1997 Elsevier Science B.V.