35Cl NQR Spectra of Arylsulphonamides, N-Chloro and N,N-Dichloro Arylsulphonamides

The effect of substitution in the phenyl ring on the γ (35Cl NQR) of N-Cl bonds of the N-chloroand N,N-dichloro-arylsulphonamides has been studied and correlated. The correlation of 35Cl NQR spectra of both the N-chloro and N,N-dichloro-arylsulphonamides is exceedingly good, although there was no systematic variation in the frequencies with substituents in the phenyl ring. The effect of substitution on the C-35Cl NQR of the phenyl ring has also been correlated. The deviation here is also not systematic due to the fact that the chemically equivalent chlorine atoms may exhibit different NQR frequencies due to crystal field effect. Finally, γ (C - 35Cl NQR) of all the 4-chloro-1-substitutedbenzenes have been correlated through the line diagram.

35Cl NQR Spectra of Substituted N-(Phenyl)-2,2,2-Trichloroacetamides

Several substituted acetamides, XyC6H5_ y NHCOCCl3 (X=CH3 , NO2 , or Br and y= 1 or 2) have been synthesized and studied by NQR. The effect of ring substitution on the average υ(35Cl) NQR of the trichloroacetyl group is not substantial, but it affects the crystal structure of the substituted com-pounds. The NQR spectra of XyC6H5-y NHCOCCl 3 (where Xy =4-CH3 , 4-NO2 , and 2,3-(CH3)2) show six 35Cl NQR frequencies, each indicating the presence of two molecules in their respective asym-metric units. The temperature dependence of υ(35Cl) NQR of N-(4-methylphenyl)-2,2,2-trichloroacet-amide reveals that it undergoes a first order phase transition around 205 K. Its spectrum shows six lines up to 205 K and three lines thereafter. The latter triplet part of the spectrum fades out around 250 K due to librational motions in the crystal lattice, as the torsional motions of the CCl3 group are easily excit-ed. The 35Cl NQR spectra of all the methylsubstituted amides have been compared with those of the corresponding chlorosubstituted compounds. Generally there is no systematic variation of the mean val-ues of υ(35Cl) NQR or the trichloroacetyl group with the substituents in the phenyl ring. The ω C-Cl frequencies of the trichloroacetyl group of all the v-substituted N-(phenyl)-2,2,2-trichloroacetamides have been estimated using NQR substituent parameters (k) and the frequencies of N-(phenyl)-2,2,2-tri-chloroacetamide. Agreement between these values and the experimental frequencies is quite good. The υ(35Cl) NQR of these amides has also been correlated with Σki of the substituents. Further υ(35Cl) NQR spectra of mono-and trichloroacetamides have been correlated.

Comparison of 35Cl NQR Spectra between the Mixed Crystals K2Sn1-xRexCl6 and the Al3+ Doped Crystals K2SnCl6:Al3+

Abstract35Cl Nuclear Quadrupole Resonance (NQR) has provided a valuable tool for investigating the local structure in mixed crystals K2S1-xRexCl6 and Al3+ doped crystals K2SnCl6:Al3+ . The measured NQR line shapes and relaxation times of both kinds of impurity containing crystals in the cubic phase of the host K2SnCl6 show markedly different impurity effects; static impurity effects in K2Sn1-x RexCl6 and dynamic effects in K2SnCl6 :Al3+ . The 35Cl NQR spectra of K2SnCl6:Al3+ near the transition temperature (Tc) indicate the presence of pretransition of the local structure in the high temperature cubic phase.