NQR investigations in crystalline 2,5-dichloroacetanilide

Two close NQR lines were observed in 2,5-dichloroacetanilide at room temperature at 34.606 MHz and 35.212 MHz as well as at liquid nitrogen temperature at 34.832 MHz and 35.791 MHz, using a self-quenched super-regenerative spectrometer. Analysis of the Zeeman effect on the two lines using a cylindrical single crystal reveals that the crystal belongs to either orthorhombic or monoclinic system. There are two crystallographically equivalent but physically non-equivalent directions for the principal field gradientZ axes making an angle of 77° for both resonance lines. The unit cell contains either two or a multiple of two molecules. There is an in-plane bending of the two C-Cl bonds by 1°. The ionic, single bond and double bond characters of C-C1 bonds for both chlorines are almost equal and are in the ratio 25:74:1.     

Alkoxyphenyltrichlorostannane35Cl NQR spectra

Irkutsk Organic Chemistry Institute, Siberian Branch, USSR Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 30, No. 1, pp. 169–171, January–February, 1989.     

NQR investigations in crystalline 2,6-dichlorobenzamide

Two resonance lines were observed in 2,6-dichlorobenzamide, both in liquid nitrogen and at room temperatures, using a self quenched super-regenerative NQR spectrometer. Analysis of the Zeeman effect on the two lines using an uncut crystal grown from solution reveals: (1) the crystal belongs to the orthorhombic system; (2) there are two crystallographically equivalent but physically non-equivalent directions for the principal field gradient making an angle of 71° for the low frequency line, and four such directions for the high frequency line; (3) the directions of the crystalline axes a, b and c are tentatively fixed as (90°, 90°), (90°, 90°) and (0°,—); (4) from morphological studies a: b: c are estimated as 0.959 ± 0.005: 1:1,402 ± 0.005 and, from the estimated density (1.440 gms/cc) of the crystal, the absolute values a, b, c are calculated, on the basis of four molecules per unit cell, as a = 8.33 Å, b = 8.68 Å and c = 12.18 Å; (5) there are a mininium of four molecules per unit cell; the four molecules lie in four different planes which are, however, connected by symmetry operations. There is an inplane bending by 6.5° between the two C? Cl bonds away from one another and (6) the ionic, single bond and double bond characters for both chlorines are almost equal and are in the ratio 25:72:3.     

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 and79Br NQR spectra of halofluorosulfates

Conclusions NQR spectroscopy was used to find the localization of formal positive charge on the chlorine and bromine atoms in ClOSO₂F and BrOSO₂F.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 244–245, January, 1986.     

35Cl NQR spectrum of WS2SeCl5

Conclusions NQR spectroscopy indicates that tungsten thioselenium chloride is a complex of tungsten thiochloride and selenium dichloride with inequivalent chlorine atoms at the metal atom.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1873–1875, August, 1987.     

35Cl NQR spectra of several aryl chloromethyl ethers

Conclusions There is a significant specific geminal interaction of the oxygen and chlorine atom in aryl chloromethyl ethers, p-RC₆H₄OCH₂Cl, although this effect is less than in alkyl chloro-methyl ethers.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1195–1197, May, 1985.     

35Cl NQR spectra of several rhenium chalcochloride complexes

The³⁵Cl NQR spectra were studied for rhenium chalcochloride complexes ReX₂Cl₁₂ (X=Se, Te), Re₂XCl₁₂ (X=S, Se), and thet- and-forms of ReCl₄ and the⁷⁹Br NQR spectrum of ReBr₃ were also studied. The ReX₂Cl₁₂ complexes were found to have ReCl₆(XCl₃)₂ structure, while Re₂SCl₁₂ has Re₂Cl₉(SCl₃) structure; the selenium analog has a more complex structure. Significant differences in the halide ions were also found in rhenium halides.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 192–195, January, 1991.     

35Cl and79Br NQR spectra of dicyclopentadienylzirconium halides

Conclusions The NQR frequencies of the³⁵Cl and⁷⁹Br atoms in dicyclopentadienylzirconium dichloride and the corresponding dibromide are 25–30% lower than for the analogous titanium derivatives, which corresponds to a greater involvement of the P electrons of the halogen atoms in the Zr-Hal bond than in the Ti-Hal bond.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1895–1897, August, 1979.The authors are indebted to G. K. Semin for his interest in the work, and to R. Kh. Freidlina and É. M. Brainina for supplying the study samples.     

35Cl NQR spectra of osmium and iridium chlorochalcogen complexes

Conclusions A study was carried out on the NQR spectra of the chlorine atoms in Os(IV) and Ir(III) complexes with sulfur, selenium, and tellurium chlorides as ligands. The ECl₃ group coordinates as the ligand in the osmium compounds studied.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1409–1411, June, 1986.     

35Cl NQR and structural-dynamic properties of crystalline CCl3C(O)OC6H2Cl3-2,4,6

The temperature dependences of the resonance frequency and quadrupole spin-lattice relaxation time of the chlorine-35 nuclei in crystalline CCl₃C(O)OC₆H₂Cl₃-2,4,6 were studied. Owing to the presence of resonant nuclei in various fragments of the molecules, the character of dynamics of these molecular fragments and the entire molecule was established. It is shown that thermal librations of molecules are quasiharmonic over the whole temperature range from 77 K to the melting point of the crystal. The reorientational motion of the CCl₃ group bonded to the three-coordinated carbon atom was revealed. This motion causes an exponential increase in the spin-lattice relaxation time of the chlorine nuclei of this group and subsequent damping of NQR signals (chlorine-35 resonance signals of the aryl radical were observed before melting of the sample). The activation energy of the reorientational motion is found; its value, which is 27.3 kJ/mole, is considered in comparison with the activation energies obtained by the Cl NQR method in solids for CCl₃ reorientations in similar molecular structures.     

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.     

35Cl NQR spectra and molecular structure of cyclic chlorophosphoranes

The structure of chlorine-containing cyclic pentacoordinated phosphorus compounds has been studied by³⁵Cl NQR. The distortion of molecular geometry from trigonal bipyramid to tetragonal pyramid in going from monocyclic phosphoranes to spiro phosphoranes and the corresponding changes in the NQR spectrum are discussed.Perm State University. Institute of Organic Chemistry, Ukrainian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 34, No. 3, pp. 75–79, May–June 1993.Translated by L. Smolina     

Cl35 NQR spectra and the transmission effects in the series RSO2Cl

Conclusions It was shown by correlating the Cl³⁵ NQR frequencies with the Taft _I and _c parameters that the effect of substituents, which are either capable of conjugation (Hal, OR, NR₂) or are alkyl groups, is transmitted to the chlorine atom through the SO₂Cl group by a practically purely inductive means.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 486–488, February, 1970.     

14N and 35Cl NQR studies of organophosphorus compounds

¹⁴N and ³⁵Cl NQR spectra have been investigated for 24 organophosphorus compounds using a pulse technique. The electron populations of the nitrogen lone pair orbital and the N? P bond are calculated according to the Townes and Dailey method. The experimental data are interpreted assuming a partial double bond character of the N? P bond due to the p_π? d_π interaction and p_π? σ conjugation of the lone pair electrons of the nitrogen atoms. The effect of the different nature of substituents X on the N? P bond populations is observed in X ? PR_n (R₂N)_3-n molecules (where X is O, S, Se, or lone pair electrons and n = 0, 1, 2). It can be seen from this dependence that the effective electronegativity of the phosphorus atom is largest in selenophosphoramidates and falls in the sequence P?Se > P?S > P?O > P.     

35Cl NQR and dynamic structure of pentafluorochlorobenzene in the solid state

Institute of Crystallography, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 4, pp. 170–171, July–August, 1991.