Abstract
Nuclear quadrupole resonances of I, Br, Cl, As and Sb isotopes in solids AsCl3, SbCl3, SbBr3, AsI3, SbI3, AsI3·3S8, SbI3·3S8, SnI4, SnI4·2S8 and SnI4·4S8 have been measured systematically. The newly obtained coupling constants eQq and asymmetry parameters η of the I127 resonances at 77°K are as follows: eQq=1383.03, 1402.68 Mc: η=0.002, 0.039 in SnI4·2S8, eQq=1364.3, 1368.3, 1405.0 Mc and η=0.00, 0.00, 0.03 in SnI4·4S8. In SnI4·4S8 an additional line was observed at 219.04 Mc corresponding to the first resonance. The second resonance of SbI3 was at 254.637 Mc with eQq=895.83 Mc and η=0.565. Resonance frequencies of As75 in AsI3 and AsI3·3S8 at 77°K were 29.338 and 49.501 Mc, respectively. The first resonance of Sb121 in SbI3 was 25.406 Mc at 77°K and the corresponding resonance in SbI3·3S8 was 37.461 Mc at 297°K. SbBr3 showed two crystal forms which gave Sb121 coupling constants of 319.920 and 316.02 Mc and asymmetry parameters of 0.082 and 0.182 at 304°K, respectively. On the Br resonances of SbBr3 three resonance lines instead of two hitherto reported were observed in both crystal forms.
Coupling constants of trihalides were compared with their chemical bond properties. The constants of AsI3 and SbI3 are different from those of other compounds, while their sulphur moleculor addition compounds are in rather good agreement.
AsI3 showed positive temperature dependency for arsenic isotope as for the case of iodine isotope.
