Formation of cyclophosphazene clathrate compounds by vapour–solid reaction: four crystalline forms depending on guest molecules

Abstract

Tris(naphthalene-2,3-dioxy)cyclotriphosphazene (TNDOCTP) is known to form a channel-type clathrate with e.g. benzene or chloroform. A thin amorphous film of TNDOCTP prepared by the vacuum-deposition method has been investigated, it reacted with various kinds of gaseous organic molecules forming clathrate compounds through a vapour–solid reaction. The amorphous film of TNDOCTP was crystallized on forming clathrates and the unit-cell dimensions of the crystalline reaction products were determined by electron and X-ray diffraction methods. They can be classified into four crystalline forms (benzene, hexafluorobenzene, p-xylene and ferrocene) according to unit-cell sizes and space groups depending on the guest molecules. In some cases the amorphous film crystallized as a guest-free crystal which includes no guest molecules. The detection of the guest molecules in the crystals was made by elemental analyses by electron energy-loss spectroscopy (EELS).