Computer simulation of the incommensurate structure of channel clathrates of thiourea by the atom-atomic potential method

Chlorine-35 NQR and1H NMR study of guest structure and dynamics in the thiourea-hexachloroethane inclusion compound

“…More effective cross-relaxation is expected in the case when a molecule slowly runs in turn through a number of positions corresponding to different values of EFG and thus to different quadrupole splittings. As mentioned above, atom-atom potential calculation predicts an almost barrierless propagation of the domain walls along the channel [26]. In this case, instead of the random jumps of each separate molecule, all molecules exhibit a collective, simultaneous translational and rotational (around their C 3 axes) motion.…”

“…Our recent atom-atom potential calculation of channel non-stoichiometric thioureahexachloroethane inclusion compound [26] showed that its structure is different from C and IC states mentioned above. It was found that the guest sublattice in this compound comprises two types of finite molecular chains having different structure and separated by the domain walls [26].…”

“…Our recent atom-atom potential calculation of channel non-stoichiometric thioureahexachloroethane inclusion compound [26] showed that its structure is different from C and IC states mentioned above. It was found that the guest sublattice in this compound comprises two types of finite molecular chains having different structure and separated by the domain walls [26]. In the present paper we present the results of 35 Cl NQR and 1 H NMR measurements of thiourea-hexachloroethane, [2.95(NH 2 ) 2 CS]C 2 Cl 6 , in the temperature range from 7.5 to 90 K, which confirm this model and show the existence of such a state at least below 60 K. Two resonances in the NQR spectra were assigned to the two commensurate or nearly commensurate regions, while the third resonance, showing the anomalous behaviour, was attributed to the guest molecules in the domain wall.…”

“…However, the structure of the guest sublattice in this compound was unknown. Therefore, the numerical calculation of this structure by means of the atom-atom potential method has been undertaken [26]. Calculation was based on the aforementioned conventional rhombohedral thiourea tunnel structure [27] with a molecular C 3 symmetry axis lying along the channel.…”

“…Calculation was based on the aforementioned conventional rhombohedral thiourea tunnel structure [27] with a molecular C 3 symmetry axis lying along the channel. Details of the calculation are given elsewhere [26].…”