Nuclear Quadrupole Resonances in Arsenic and Antimony Trihalides and Sulphur Molecular Addition Compounds

Nuclear quadrupole resonances of I, Br, Cl, As and Sb isotopes in solids AsCl 3 , SbCl 3 , SbBr 3 , AsI 3 , SbI 3 , AsI 3 ·3S 8 , SbI 3 ·3S 8 , SnI 4 , SnI 4 ·2S 8 and SnI 4 ·4S 8 have been measured systematically. The newly obtained coupling constants e Q q and asymmetry parameters η of the I 127 resonances at 77°K are as follows: e Q q =1383.03, 1402.68 Mc: η= 0.002, 0.039 in SnI 4 ·2S 8 , e Q q =1364.3, 1368.3, 1405.0 Mc and η=0.00, 0.00, 0.03 in SnI 4 ·4S 8 . In SnI 4 ·4S 8 an additional line was observed at 219.04 Mc corresponding to the first resonance. The second resonance of SbI 3 was at 254.637 Mc with e Q q =895.83 Mc and η=0.565. Resonance frequencies of As 75 in AsI 3 and AsI 3 ·3S 8 at 77°K were 29.338 and 49.501 Mc, respectively. The first resonance of Sb 121 in SbI 3 was 25.406 Mc at 77°K and the corresponding resonance in SbI 3 ·3S 8 was 37.461 Mc at 297°K. SbBr 3 showed two crystal forms which gave Sb 121 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 SbBr 3 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 AsI 3 and SbI 3 are different from those of other compounds, while their sulphur moleculor addition compounds are in rather good agreement. AsI 3 showed positive temperature dependency for arsenic isotope as for the case of iodine isotope.