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1986[X]
21Author    V. Santhanam, J. SobhanadriRequires cookie*
 Title    Nuclear Quadrupole Coupling Constant and Conformational Studies  
 Abstract    A molecular conformation study on three 3-monosubstituted derivatives of propene has been carried out by evaluating the EFG at the site of the halogen nucleus using a semi-empirical LCAO-MO-SCF method. Calculations are performed on several conformers at INDO and CNDO level, using "sp" and "spd" valence basis sets, with Slater type orbitals as the basis functions. The results obtained for various conformers indicate that the nuclear quadrupole coupling constant is practically independent of the orientation of the CH2X group (X = Cl, Br and I) (Figure 1). The mean value of e2 Qqz:/h (averaged over all conformers) in each system matches favourably with the experimental value, despite the severe approximations that are inherent in the semi-empirical theory as well as in its 
  Reference    Z. Naturforsch. 41a, 166 (1986); revised version received October 22 1985 
  Published    1986 
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 TEI-XML for    default:Reihe_A/41/ZNA-1986-41a-0166.pdf 
 Identifier    ZNA-1986-41a-0166 
 Volume    41 
22Author    Y. Umasasidhar, S. Ramaprabhu, K.V S Rama RaoRequires cookie*
 Title    Investigation of EFG Parameters at the Halogen Site in XO3 and XOje Radicals (X = Cl, Br) in Certain Inorganic Solids  
 Abstract    Electric field gradients at the halogen site in XO3 and XO 3 0 radicals (X = Cl, Br), formed by the y-irradiation o f single crystals o f N aC 103 , K C103 , K B r03 and S r (B r 0 3)2 -H20 have been evaluated by MO calculations using the C N D O /2 m ethod. The symmetry o f the X 0 3 radicals is assumed to be that o f XO® ions which have C 3v symmetry, whereas X 0 3 radicals are assumed to have Cs symmetry with one X —O bond distance being stretched due to the excess electron. The results are in good agreement with the experimental values deduced from published ESR studies on these single crystals. 
  Reference    Z. Naturforsch. 41a, 169 (1986); revised version received October 22 1985 
  Published    1986 
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 TEI-XML for    default:Reihe_A/41/ZNA-1986-41a-0169.pdf 
 Identifier    ZNA-1986-41a-0169 
 Volume    41 
23Author    M. Frank, F. Gubitz, W. Ittner, W. Kreische, A. Labahn, B. Röseler, G. WeeskeRequires cookie*
 Title    9F Nuclear Quadrupole Coupling in some Halomethanes  
 Abstract    The l9F quadrupole coupling constants in CF4, C H F 3, CC1F3 and CHC1F2 are reported. The measurements were carried out tem perature dependent using the time differential perturbed angular distribution method (TDPAD). The tem perature dependence can be satisfactorily described in the framework of the Bayer-Kushida theory. A simple model is used to explain the appearance of H -F and C l-F coupling constants in C H F3/CHC1F2 and CC1F3, respectively. 
  Reference    Z. Naturforsch. 41a, 171—174 (1986); received Spetem ber 23 1985 
  Published    1986 
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 TEI-XML for    default:Reihe_A/41/ZNA-1986-41a-0171.pdf 
 Identifier    ZNA-1986-41a-0171 
 Volume    41 
24Author    A. C. Buchanan, Iii, Ira Rubin, Alarich Weiss, DanielA. Davis, Kevin Bass, RogerW. Todd, Charles Chia, -Chung JuiRequires cookie*
 Title    Gary Wulfsberg [1 a]  
 Abstract    Solution and magic-angle-spinning solid-state 13C NM R spectra are reported for ^'-(penta-chlorocyclopentadienyl)(pentamethylphenyl) mercury, C6Me5HgC5Cl5 (II). The latter suggests that II is fluxional in the solid state. Some expected consequences o f fluxional behavior also appear in the 35C1 NQR spectra of II and several related pentachlorocyclopentadienylmercurials. 
  Reference    Z. Naturforsch. 41a, 175—178 (1986); received July 22 1985 
  Published    1986 
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 Identifier    ZNA-1986-41a-0175 
 Volume    41 
25Author    Claudine Gerard-Dion, Joyce Rupp-Bensadon, EdwinA C LuckenRequires cookie*
 Title    Nuclear Quadrupole Resonance Studies of Chelated Antimony Complexes. Part HI. The Carboxylates: R C 0 2 SbCl4  
 Abstract    The 35C1, 121 Sb and I23Sb resonance frequencies for seventeen tetrachloro(carboxylato)anti-mony V compounds, R C 0 2SbCl4, are reported. The results confirm the difference in the effects of the substituent on the equatorial chlorine atoms and the axial chlorine atoms of the SbCl4 group, previously remarked in Parts I and II of this series, and this effect has been put on a more quantitative basis by correlating the observed frequencies with the pK 's o f the corresponding acids. The compounds with R = isopropyl and R = cyclopropyl both show a phase change in the region of 140 K which may correspond to reorientation o f the substituent about the R -C 0 2 axis. 
  Reference    Z. Naturforsch. 41a, 179—185 (1986); received July 23 1985 
  Published    1986 
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 TEI-XML for    default:Reihe_A/41/ZNA-1986-41a-0179.pdf 
 Identifier    ZNA-1986-41a-0179 
 Volume    41 
26Author    T. A. Babushkina, K. Yu, S.F G Volgin, UshtchinRequires cookie*
 Title    NQR Spectra of 79Br and 127I in the Halogen Derivatives of the Benzoic and Hippuric Acids  
 Abstract    revised version received Septem ber 25, 1985 Q uadrupole interactions in ortho-, meta-and para-Br-and I-benzoic and hippuric acids have been studied by means of N Q R spectroscopy. It is shown that the formation of the Na-salts results in N QR frequency changes. The tem perature dependence of the 79Br and 127I N Q R fre­ quencies in the para-halogen derivatives of the benzoic and hippuric acids are investigated. The 127I NQR spectra in a few derivatives of 2, 4, 6-I3C6H 2COOH are studied at 77 K. 
  Reference    Z. Naturforsch. 41a, 186—189 (1986) 
  Published    1986 
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 TEI-XML for    default:Reihe_A/41/ZNA-1986-41a-0186.pdf 
 Identifier    ZNA-1986-41a-0186 
 Volume    41 
27Author    T. A. Babushkina, A. A. Boguslavsky, A.G D UdarevaRequires cookie*
 Title    81 Br and 127I NQR of Rare Earth Trihalogenides REX3, X = Br, I  
 Abstract    The 81 Br N Q R spectra of REBr3, RE = Dy, Ho, Yb, Sm, and the 127I N Q R spectra of REI3, RE = Dy, Ho, Sm. are reported. Additionally 127I N QR data of RbHoLj, KSml,*, and R b3Sm 2l9 are given. The line shape of the 12 I NQR of HoI3 was studied in external magnetic fields up to 300 Gauss. 
  Reference    Z. Naturforsch. 41a, 190—191 (1986); revised version received Novem ber 5 1985 
  Published    1986 
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 TEI-XML for    default:Reihe_A/41/ZNA-1986-41a-0190.pdf 
 Identifier    ZNA-1986-41a-0190 
 Volume    41 
28Author    A. Peneau, B. M. Anallah, L. G. UibeRequires cookie*
 Title    Nitrogen-14 NQR in s-Triazine Derivatives  
 Abstract    W ithin a study of the tem perature dependence of N Q R frequencies in some s-triazine derivatives [1], resonance frequencies at 4.2 K were determined in melamine, cyanuric acid, and cyanuric chloride. New lines, which were not reported so far, were detected in two of these compounds. In melamine, nine more lines were found as already described in [4], In cyanuric chloride, two more lines were found showing a second nitrogen site, in agreement with the existence of two chlorine N Q R sites in this compound. 
  Reference    Z. Naturforsch. 41a, 192—194 (1986); revised version received September 15 1985 
  Published    1986 
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 TEI-XML for    default:Reihe_A/41/ZNA-1986-41a-0192.pdf 
 Identifier    ZNA-1986-41a-0192 
 Volume    41 
29Author    P.M G Bavin, D. Stephenson, J.A S SmithRequires cookie*
 Title    4N Quadrupole Cross-Relaxation Spectroscopy of a Compound of Pharmacological Interest  
 Abstract    Cross-relaxation spectroscopy has been used to record the 14N quadrupole resonance spectrum of two of the polym orphic forms of the pharm acologically-im portant compound: 2-4-(5-Bromo-3-m ethylpyrid-2-yl)butylammo-5-(6-methylpyrid-3-yi)methyl-pyrimidin-4-one. Three 14N frequencies for four o f the non-equivalent nitrogen sites within the molecule have been identified by combined irradiation and cross-relaxation techniques and quadrupole coupling constants and asymmetry param eters deduced therefrom; the absence of 14N (and ™Br) signals from the brom ine-substituted pyridine ring suggests that this part of the molecule is disordered in the crystal. The spectral intensities have been used to derive approxim ate values for the l4N and 'H relaxation times, which show clear differences between the two polymorphs. 
  Reference    Z. Naturforsch. 41a, 195—199 (1986); received August 5 1985 
  Published    1986 
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 Identifier    ZNA-1986-41a-0195 
 Volume    41 
30Author    A. Lötz, J. Voitländer, D. Stephenson, J.A S SmithRequires cookie*
 Title    Nuclear Quadrupole Double Resonance of Compounds with Transannular Boron—Nitrogen Bonds  
 Abstract    The boron and nitrogen nuclear quadrupole double resonance spectra of several ring com­ pounds with transannular b o ro n -n itro g e n bonds are reported. The electron donation from nitro­ gen to boron as seen by their quadrupole coupling parallels the b o ro n -nitrogen bond lengths. One of the compounds exhibits a transannular valence topom erisation between two identical boron-nitrog en pairs in solution which is frozen in the solid state but may possibly exist in a preformed state o f this equilibrium from its quadrupole coupling. The oxygen-boron 7t-bond in boroxines, whose extent is deduced from the quadrupole coupling in one of the compounds with a boroxine-like structure at boron and in (PhBO)3, is approximately half as strong as the nitrogen-boro n 7t-bond in borazine. 
  Reference    Z. Naturforsch. 41a, 200—2 (1986); received August 28 1985 
  Published    1986 
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 TEI-XML for    default:Reihe_A/41/ZNA-1986-41a-0200.pdf 
 Identifier    ZNA-1986-41a-0200 
 Volume    41 
31Author    J. Olliges, A. Lötz, J. Voitländer, H. Barfuss, G. Böhnlein, F. Gubitz, W. Ittner, G. Lanzendorfer, W. Kreische, B. RöselerRequires cookie*
 Title    Boron, Nitrogen, and Fluorine Nuclear Quadrupole Coupling and the Electronic Structure of the Boron—Nitrogen Single Bond  
 Abstract    The n B and l9F nuclear quadrupole couplings in F 3BNH V(CH3)3_;(. compounds are reported. The boron quadrupole couplings were measured by quadrupole perturbed N M R in the solid state. The fluorine quadrupole couplings were obtained by the time-differential observation of the angular distribution of the gamma radiation after excitation o f the fluorine nuclei with accelerated protons (TDPAD). The results are discussed in connection with the nitrogen quadru­ pole couplings in F 3BNHV R 3_* compounds, and the nitrogen and boron quadrupole couplings in H 3BNHvR 3_x: compounds which were previously determined by nuclear quadrupole double resonance. In the F 3BNHyR 3_x series of compounds, the donor-acceptor character o f the B -N bond appears to be less im portant than in the H 3BNH V R 3_^ compounds in favour of a more ionic character of the bond with a higher negative charge on nitrogen. 
  Reference    Z. Naturforsch. 41a, 203—205 (1986); received August 28 1985 
  Published    1986 
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 TEI-XML for    default:Reihe_A/41/ZNA-1986-41a-0203.pdf 
 Identifier    ZNA-1986-41a-0203 
 Volume    41 
32Author    A. Lötz, J. Voitländer, J.A S SmithRequires cookie*
 Title    The Electronic Structure of Borazine as seen by 10B, 11B, and 14N Nuclear Quadrupole Double Resonance  
 Abstract    The nitrogen nuclear quadrupole coupling in borazine is reported and interpreted in combination with the previously measured boron coupling. A novel Townes-Dailey type of analysis was employed to obtain the electron distribution in borazine. A calculated rc-donation of ~ 0.5 e from the nitrogen atom to the vacant rc-orbital of boron is accompanied by a strong polarisation of the er-skeleton, im parting a negative charge to nitrogen and a positive charge to boron. 
  Reference    Z. Naturforsch. 41a, 206 (1986); received August 28 1985 
  Published    1986 
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 Identifier    ZNA-1986-41a-0206 
 Volume    41 
33Author    Daniel Rupp, EdwinA C LuckenRequires cookie*
 Title    The Complex between Chloromethane and Benzene  
 Abstract    35Cl Nuclear Quadrupole Resonance, NQR, spectra of mixtures of Chloromethane and Benzene, with relative molar compositions in the range 1:3 to 3:1, and at temperatures in the range 77 K to 180 K, reveals the presence of a new crystalline phase, in addition to that of pure Chloromethane. The temperature-dependence and the deuterium isotope effect of this new resonance show that the chlorom ethane molecule is much more labile in the new crystalline phase than in pure chloromethane. The existence of the new crystalline phase is confirmed by Differential Thermal Approach, DTA, which in addition provides evidence that the complex has a 1:1 composition and that the enthalpy of fusion is ~ 660 cal./mole. Raman spectroscopy provides further evidence of the existence of the complex. 
  Reference    Z. Naturforsch. 41a, 208 (1986); received August 10 1985 
  Published    1986 
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 TEI-XML for    default:Reihe_A/41/ZNA-1986-41a-0208.pdf 
 Identifier    ZNA-1986-41a-0208 
 Volume    41 
34Author    IgorM. Lazarev, G. Ennadii, V. Dolgushin, ValentinP. Feshin, MichailG. VoronkovRequires cookie*
 Title    35C1 NQR Spectra of S11CI4 Complexes with Methylaryl Ethers  
 Abstract    SnCl4 Complexes with methylaryl ethers and their 35C1 NQR spectra have been obtained. All these complexes, except SnCl4 • 1,2-(CH30) 2C6H4, have a trigonal-bipyramidal structure. The latter compound has an essentially distorted octahedral structure. One of the ligand oxygen atoms takes part in the form ation o f the SnCl4 complex with 1,3-, 1,4-(CH30) 2C 6H4 and R N 0 2. These complexes have a trigonal-bipyram idal structure too. 
  Reference    Z. Naturforsch. 41a, 211—214 (1986); revised version received October 1 1985 
  Published    1986 
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 Identifier    ZNA-1986-41a-0211 
 Volume    41 
35Author    Winfried Fichtner, Axel Markworth, N. Orbert, Weiden, Alarich WeissRequires cookie*
 Title    35 Cl NQR Spectroscopy on Salts and Molecular Compounds of Trichloroacetic Acid  
 Abstract    The temperature dependence of salts M (I)H (C l3C CO O)2 and molecular compounds of trichloroacetic acid with amines and benzaldehydes, TCA • X, was studied, The data fit rather well to the known dependence of the mean frequency shift A <v(35Cl)> on the pka difference of X with respect to TCA. A linear relation is observed between the bleaching out temperature Tb of the 35C1 N Q R lines and A (v (35C l)) for M (I)H (C l3C CO O)2 and for TCA • X, X = benzaldehydes. 
  Reference    Z. Naturforsch. 41a, 215 (1986); revised version received Septem ber 22 1985 
  Published    1986 
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 Identifier    ZNA-1986-41a-0215 
 Volume    41 
36Author    Mariusz Mackowiak, Piotr Koziol, Jan StankowskiRequires cookie*
 Title    Pressure Dependence of the Proton Transfer Equilibrium in Hydrogen Bonded Complexes  
 Abstract    35Cl NQR measurements were carried out on complexes o f pentachlorophenol with nitrogen bases as a function of pressure (up to 300 MPa) and o f tem perature. It is shown that the sign and magnitude of the pressure coefficient o f the 35Cl NQR frequency is related to the degree of proton transfer. An anomaly in the pressure coefficient of v (35Cl) has been observed near 50% of the proton transfer in the hydrogen bond. This anomaly is discussed assuming that the proton transfer equilibrium is pressure dependent. The fact that the transition from the double-well potential of the hydrogen bond to the single-well potential occurs in the critical manner is also taken into account. 
  Reference    Z. Naturforsch. 41a, 225 (1986) 
  Published    1986 
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 Identifier    ZNA-1986-41a-0225 
 Volume    41 
37Author    Koji Yamada, TsutomU. Okuda, Hisao NegitaRequires cookie*
 Title    81Br and 27Al NQR of AlBr3 2C5H5N, AlBr3 1.5CH3CN, and AlBr3 2CH 3CN  
 Abstract    81Br N QR was studied in AlBr3 ■ 2 C 5H5N, AlBr3 • 1.5CH3CN, and AlBr3 • 2 CH 3CN. From the N Q R spectra it is apparent that the solid compounds are build up by ion pairs [AlBr2(C 5H 5N)4 , AlBrj], [A1(CH3CN)^+, 3AlBr;], and [AlBr(CH3C N)f+, 2 AlBrj-C H 3CN], respectively. 21 Al NQR detected by SEDOR technique supports these structural models. Using these N Q R param e­ ters, the metal-ligands interactions in the six-coordinated complexes is discussed on the basis of the donor strength. In the case of AlBr3-2 C H 3CN two types of reorientational motion of the AlBrj tetrahedra were detected from the spin lattice relaxation times and from fade-out phe­ nomena of the 81 Br N Q R signals. 
  Reference    Z. Naturforsch. 41a, 230—235 (1986); received July 23 1985 
  Published    1986 
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 TEI-XML for    default:Reihe_A/41/ZNA-1986-41a-0230.pdf 
 Identifier    ZNA-1986-41a-0230 
 Volume    41 
38Author    S. Indumathy, K. R. Sridharan, J. Ramakrishna, G. WulfsbergRequires cookie*
 Title    Halogen NQR Studies in Certain Mercuric Halide-Polyether Complexes  
 Abstract    The temperature variation of 35Cl and 81 Br NQR frequencies are reported for mercuric chloride ■ triethylene glycol dimethyl ether (HgCl2 • triglyme), mercuric chloride ■ diethylene glycol dimethyl ether (HgCl2 • diglym e), and mercuric bromide • diethylene glycol dimethyl ether (HgBr2 • diglyme). The frequencies have been assigned to the appropriate halogens using molecular models which take into account the various intra-and inter-molecular interactions in the solid state. The observed temperature variation o f the NQR frequencies, in the range 77 -300 K. has been analysed using the two torsional m ode analysis in the framework of the Bayer-Kushida-Brown method with Tatsuzaki's correction to obtain the torsional frequencies and their average temperature coefficients. 
  Reference    Z. Naturforsch. 41a, 236 (1986); revised version received October 12 1985 
  Published    1986 
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 Identifier    ZNA-1986-41a-0236 
 Volume    41 
39Author    Rama BasuRequires cookie*
 Title    Nuclear Quadrupole Resonance Studies on Molecular Complexes  
 Abstract    NQR studies of a number of molecular complexes with p-chloronitrobenzene and o-chloro-nitrobenzene as acceptors and different hydrocarbons as donors were carried out. A linear relationship between the NQR shift and the ionization potentials of the donors is obtained. Maksyutin's idea of a positive shift with respect to acceptors having a quadrupolar nucleus is shown to hold in those systems. Townes and Dailey's method was applied to calculate the change in the ionicity of the C-Cl bond on complexation to account for the a-electronic contributions in the systems. 
  Reference    Z. Naturforsch. 41a, 240 (1986); revised version received October 11 1985 
  Published    1986 
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 Identifier    ZNA-1986-41a-0240 
 Volume    41 
40Author    N. Obuo, N. Akam UraRequires cookie*
 Title    NQR Studies of Phase Transitions and Intermolecular Interactions in Crystals  
 Abstract    Simple methods to analyze the anomalous behavior of NQR parameters are presented. Unusual positive temperature coefficients of antimony resonance frequencies in (NH4)2SbF5 below the phase transition at 169 K were interpreted in terms of ordering processes of the am monium ions. Calculation of the EFG in LaF3 revealed that the translational diffusion o f Li ions brings about an anomalous decrease in // of the 139La N Q R at high temperatures. The sam e kind o f an EFG calculation was made to predict the 14N N Q R frequency in Li3N . The calculation of the intermolecular potential energy was used to evaluate the potential barrier to molecular rotation in C6Cl6 and sym-C6Cl3F3. It was shown in the latter that the quadrupolar relaxation, due to a reorientational jum p to a metastable site, works in the low temperature phase below 296 K. while the molecular three-fold reorientation is the dominant relaxation mechanism in the high temperature phase. 
  Reference    Z. Naturforsch. 41a, 243 (1986); received July 22 1985 
  Published    1986 
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 TEI-XML for    default:Reihe_A/41/ZNA-1986-41a-0243.pdf 
 Identifier    ZNA-1986-41a-0243 
 Volume    41 
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