75As NQR in cyclic arsenic compounds

Electronic and spatial structure of five-membered oxygen-or sulfur-containing cyclic phosphorus and arsenic compounds based on quantum-chemical calculations

“…The experimental NQR frequencies for these compounds should also be insignificantly different. However, in the literature [2], an experimental 35 Cl NQR frequency is given for compound 4 that is significantly lower than for 3 (Table 1). Most likely the 35 Cl NQR frequency for compound 4 is given incorrectly in [2].…”

“…This is explained by the fact that the sulfur atom is leas capable of p π -σ conjugation than the oxygen atom [2]. We hypothesize that such a ratio of the NQR frequencies and electron densities for these oxygen-and sulfur-containing compounds is because of polarization of the Z-Cl bonds due to the action of the charge on the S or O atom directly through the field, as in other compounds containing a nonlinear triatomic group Y-Z-M or Y-Z=M (see, for example, [3][4][5][6]).…”