Effect of Adjacent-molecule rotation on NQR frequencies

The effect of rotation of ions or molecules on the NQR frequencies of nuclei in adjacent ions is considered in the framework of the theory of Chihara (ref. 1). The theory provides an adequate explanation of the temperature dependence in [Ca.6H₂O] [SnCl₆], but fails to explain details of pressure dependence measurements on NH₄ReO₄.     

Relationship between the 79Br NQR frequencies of crystallographically Inequivalent bromine atoms in CBr4 and their field constants

For the crystallographically Inequivalent positions of the bromine atoms in CBr₄, there exists an equation that relates the frequencies v of ⁷⁹Br NQR to their field constants α = dv/dE _z . This equation can be used to determine the strength of the local electric fields.     

35Cl NQR spectra, structure, and mutual influence of substituents in the series of chlorine-containing organic compounds of pentavalent phosphorus

Regularities of transmission of the effect of equatorial and axial substituents were established for a number of chlorine-containing organic compounds of pentatalent phosphorus using³⁵Cl NQR spectra. The field constants of³⁵Cl NQR frequencies of the chlorine atoms participating in the P−Cl bond were estimated for a series of tetrahedral phosphorus ions. The³⁵Cl NQR frequencies of chlorine atoms in tetracoordinated ions of pentavalent phosphorus and in analogous isoelectronic silicon compounds are related by a linear dependence. Deceased Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 915–922, May, 1999.     

Effect of substituents at atoms of double bonds on the conformation of the 1,3-cyclohexadiene ring

The effect of alkyl substituents at atoms of double bonds on the conformation of the 1,3-cyclohexadiene ring was studied using a molecular-mechanics method. It was shown that the introduction of substituents results only in a change of the degree of ring puckering. It is concluded that there is equilibrium between flattening and unflattening factors, which then governs the constancy of the ring conformation.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 28, No. 4, pp. 334–337, July–August, 1992.     

Relation between 35Cl NQR frequencies and spin-lattice relaxation times in HGeCl3

An equation relating ³⁵Cl NQR frequencies toinverse spin-lattice relaxation times was found for HGeCl₃ crystalline phases. The equation was used to identify shortand long-range order contributions to the NQR frequency in the environment of the resonance chlorine atom. Changes in the strength of local electric fields caused by the crystal field were determined.     

Correlation of 35Cl NQR frequencies with chlorine-atom p-orbital populations and charges in organic,silicoorganic, and inorganic chlorides

SCF MOLCAO calculations in the CNDO/2 approximation (valency sp basis) are presented for organic, heteroorganic, and inorganic chlorine compounds in the XCl series. Satisfactory correlations are obtained between the calculated charges on the Cl atoms, the populations of the p orbitals, and the numbers of unbalanced electrons on the one hand with the observed ³⁵Cl NQR frequencies for the corresponding compounds in the XXXCCl and XCl series. These indicate that the Townes-Daly approximation in NQR spectroscopy is completely applicable even in the quantitative evaluation of chlorine-atom electron-density distributions in molecules.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 22, No. 1, pp. 26–31, January–February, 1986.     

Temperature dependence of 35Cl NQR in 2,6-dichloropyridine

Chlorine NQR in 2,6-dichloropyridine has been investigated in the temperature range 77 K to room temperature and a single resonance line has been observed throughout. Using this data, torsional frequencies of the molecule have been evaluated on the basis of both the Bayer theory and the modified Bayer theory incorporating Tatsuzaki correction.     

35Cl NQR Studies of the Geometry of Aromatic Imines

The preferred conformation of solidphase R4benzylidene3,4dichloroaniline molecules has been established by nuclear quadrupole resonance (NQR) combined with quantum chemical calculations. The conformational effect of substitutes reported previously is proved. The rotation angle of the plane of the aniline ring with respect to the plane of the azomethine bond is given.