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21	Author	EdwinA C Lucken	Requires cookie*
	Title	The Nuclear Quadrupole Resonance of the 6365Cu Nuclei in Copper (I) Complexes
	Abstract	The 63Cu N Q R spectra of Cu(I) complexes are surveyed and discussed in terms of the coordina tion num ber of the copper atom , the nature of the ligands and the charge of the complex.
	Reference	Z. Naturforsch. 49a, 155—166 (1994); received August 23 1993
	Published	1994
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	TEI-XML for	default:Reihe_A/49/ZNA-1994-49a-0155.pdf
	Identifier	ZNA-1994-49a-0155
	Volume	49

22	Author	G. V. Dolgushin, I. M. Lazarev, L. I. Larina, V. A. Lopyrev, M. G. Voronkov	Requires cookie*
	Title	A 35Cl NQR and MNDO study of 3,5-dichloro-l,2,4-triazole and its ionic forms
	Abstract	The 3 5 C1 N QR spectra of 3,5-dichloro-l,2,4-triazole derivatives have been examined. M N D O calculations of chloroazoles (imidazole, triazole) including their ionic forms have been carried out. In 3,5-dichloro-l,2,4-triazole complexation and protonation occur of position 4 at the triazole ring.
	Reference	Z. Naturforsch. 49a, 167—170 (1994); received July 23 1993
	Published	1994
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	TEI-XML for	default:Reihe_A/49/ZNA-1994-49a-0167.pdf
	Identifier	ZNA-1994-49a-0167
	Volume	49

23	Author	G. V. Dolgushin, P. A. Nikitin, YuE. Sapozhnikov1, M. Yu, V. G. Dmitrichenko, M. G. Rozinov2, Voronkov	Requires cookie*
	Title
	Abstract	N Q R frequencies and asymmetry parameters (//) of 3 5 C1 chlorine-containing 1,5,2-diazaphospho-rine derivatives are reported and discussed. N M D O calculations with total optimization of geometry have been carried out. The vcal and rjcal values, calculated by means of the Townes and Dailey theory, correlate well with the experimenal data.
	Reference	Z. Naturforsch. 49a, 171—173 (1994); received July 23 1993
	Published	1994
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	TEI-XML for	default:Reihe_A/49/ZNA-1994-49a-0171.pdf
	Identifier	ZNA-1994-49a-0171
	Volume	49

24	Author	Shi	Requires cookie*
	Title	Halogen NQR and Crystal Structure of Ammonium Halides (R -N H 3) + X -and (X") (+H3NR'NH3 +) (X '). R = (HOCH2)3C, R' = CH2C(CH3)2CH2; X = I,Br
	Abstract	The 1 2 7 I-NQR of(H O C H2)3 C N H 3 I -was determined in the range 77 < T /K <310. At T = 310 K the NQR signal fades out (Tm = 463 K). The 127I spectrum (T =77 K.): v, =29.195 MHz, v2 = 14.597 MHz, rj(121l)=0, e Q # zz6 _ 1 (1 2 7 I) = 97.315 MHz, is in agreement with the crystal structure. The 127I NQR spectrum of l,3-diammonium-2,2-dimethylpropane diiodide, (H3 NCH2 C (CH3) 2 CH2 N H 3)2+ -2 1 ", is a quartet within the whole temperature range investigated, and the lines correspond to two crystallographically independent iodines: Space group P2x/c, Z = 4, a = 731.2(3) pm, 6 = 689.0(3) pm, c = 2255.1(8) pm, 0 = 104.90(1)°. At 7 = 7 7 K the 127I NQR quartet is (MHz): vx = 34.145, v2 = 32.805, v3 = 22.113, v4 = 16.787; at 295 K (same order, MHz): 30.559, 29.729, 19.810, 15.651. There are two combinations of the NQR frequencies. Considering the coordination of I", the hydrogen bonds N -H • • • I, eQ<PzzQ h~ \ and tj, we choose for I(1) Vj and v3, for I(2) v2 and v4. At 77 K eQ<Pzzh~1 (I(1))= 118.86 MHz, f?(1 2 7 I(1)) = 0.498, eQ<Pzzh~l (I(2,) = 109.75 MHz, ^(1 2 7 I(2)) = 0.135 follow for the two iodine atoms. Both, eQ<Pzzh~1 (I(1)) and e 0 .,Q h ~ 1 (I<2)) de crease smoothly with increasing T\r\(I(2)) increases with increasing T whereas ^(1 2 7 I(1)) is almost constant within 7 7 < T /K < 4 0 6 . The 7 9 81Br NQR spectrum of l,3-diamino-2,2-dimethylpropane dihydrobromide is also a quar tet, showing two crystallographic inequivalent Br atoms in the unit cell. The frequencies are (T =273 K, MHz): vt (7 9 Br)= 14.303, v2 (7 9 Br)= 12.884, (8 1 Br)= 11.951, v2 (81 Br) = 10.781; space group C2/c, Z = 8 , a = 2136.4(6) pm, 6 = 854.6(3) pm, c = 1125.8(3) pm, /? = 93.23(1)°. Crystal structures and NQR results are discussed.
	Reference	Z. Naturforsch. 49a, 174—184 (1994); received October 1 1993
	Published	1994
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	TEI-XML for	default:Reihe_A/49/ZNA-1994-49a-0174.pdf
	Identifier	ZNA-1994-49a-0174
	Volume	49

25	Author	Tsutomu Okuda, Yoshihiro Kinoshita, Hiromitsu Terao, Koji Yamada	Requires cookie*
	Title	Structure and Bonding of Bromoantimonate (III) Complexes with Unusual Valency by Means of NQR and Powder X-Ray Diffraction
	Abstract	NQR and powder X-ray diffraction were observed for several bromoantimonate (III) complexes which contain C"H2n+ jNF^ (n = 1 -3) or (C"H2lt + 1)2N H 2 (n = 1 -4) as a cation. The bond character, anion structure, crystal structure, and phase transition are discussed on the basis of the three-center-four-electron bond. A good correlation was found between the halogen NQR frequency and the Sb-X bond length.
	Reference	Z. Naturforsch. 49a, 185—192 (1994); received July 23 1993
	Published	1994
	Keywords	81Br NQR, Temperature dependence, Phase transition, Crystal structure
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	TEI-XML for	default:Reihe_A/49/ZNA-1994-49a-0185.pdf
	Identifier	ZNA-1994-49a-0185
	Volume	49

26	Author	SundaraR. Am Aprabhu, EdwinA C Lucken, Gerald Bernardinelli	Requires cookie*
	Title	Crystal Structure and NQR of Two Copper (I) Complexes of 4,6-Dimethylpyrimidine-2-thione
	Abstract	The crystal structure and 63Cu NQR spectra of two neutral hexanuclear Cu(I) complexes of 4,6-dimethylpyrimidine-2-thione, (Hdmpt); [dmptCu]6 6 CHCl3 (l) and [dmptCu]6 C2 H4 Cl2 (2), are reported. The number and relative intensities of the NQR resonances are in agreement with the results of the crystallographic study. The temperature-dependence of the resonances reveals that both compounds undergo a phase-change in the temperature range 77 K -3 0 0 K, both of which may be associated with the loss of a symmetry-element present in the high-temperature phase. The 3 5 C1 resonances of CHC13 in 1 could be observed in the low-temperature phase but the corresponding resonances for C2 H4 C12 in 2 were not detected.
	Reference	Z. Naturforsch. 49a, 193—198 (1994); received August 30 1993
	Published	1994
	Keywords	6 3 Cu, 3 5 C1, Cu(I), Crystal structure
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	TEI-XML for	default:Reihe_A/49/ZNA-1994-49a-0193.pdf
	Identifier	ZNA-1994-49a-0193
	Volume	49

27	Author	R. Am Aprabhu, N.Ahid Amstutz, EdwinA C Lucken	Requires cookie*
	Title	Sundara
	Abstract	63-65Cu and 79,81Br spectra of halogenocuprate (I) complexes containing [CuPPh3 X2]~ (X = C1, Br, I) anions with different cations were recorded in the range 77 K -3 0 0 K. The results confirm the previous trend that, for a given ligand, 63Cu NQR frequencies are in the order C l> B r > I. fe3Cu NQR frequencies in [CuPPh3 X2]_ are compared with those in neutral Cu(Ph3)2 X(X = Cl, Br) complexes and with the [CuX2] (X = C1, Br) anions, other three-coordinate Cu(I) complexes.
	Reference	Z. Naturforsch. 49a, 199—201 (1994); received August 10 1993
	Published	1994
	Keywords	6 3 Cu, 8 1 Br, Cu(I), Halogenocuprate
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	TEI-XML for	default:Reihe_A/49/ZNA-1994-49a-0199.pdf
	Identifier	ZNA-1994-49a-0199
	Volume	49

28	Author	Hirom Itsu Terao, TsutomuO., Kichiro Koto, Shi-Qi, AlarichW. Eiss2	Requires cookie*
	Title	81 Br NQR and Crystal Structure of Ethylammonium Tribromomercurate(II), CHgCHjNI-^HgBrg
	Abstract	The 81Br NQR triplet spectrum of (CH3 CH2 NH)®(HgBr3)e was measured in the range 77 K to near the m.p. (99~106°C). decreases strongly with increasing temperature, exhibiting 136.784 MHz at 77 K and 128.129 MHz at 298 K. v2 decreases from 82.060 MHz at 77 K to 76.322 MHz at 298 K. v3 increases with temperature, showing v3 = 81.292 MHz at 77 K and 84.903 MHz at 298 K. Replacement of the ammonium hydrogens by deuterium produces a negative shift of Vj and positive ones of v2 and v3 at high temperatures. These shifts change with temperature from \| — 0\| up to \|~ 2 0 0 \| kHz. The crystal structure of the title compound was determined at room temperature: P 21/m, Z = 2, a = 1021.6(8) pm, b = 643.0(6) pm, c = 691.8(6) pm, ß = 96.96 (4)°. The coordination of the mercury atom by the bromines is trigonal bipyramidal; by formation of bridges Hg • • ■ Br • • ■ Hg by one of the three bromines (Br(2)) of the planar HgBr® ions a double chain of trigonal bipyramids is formed, running along the b-axis of the crystal. B r 1' and Br(3) are single bonded to Hg. The hydrogen bonds N -H • • • Br(1 and N -H • ■ • Br(' (twice), connect the H g-B r chains to planes lying parallel to the be plane at x = 0. The relations between the Br-NQR spectrum and the structure are discussed.
	Reference	Z. Naturforsch. 49a, 202—208 (1994); received August 16 1993
	Published	1994
	Keywords	Mercury(II) Bromide Complex, Crystal Structure, 81Br NQR, * H -2D isotope effect, H-bonding
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	TEI-XML for	default:Reihe_A/49/ZNA-1994-49a-0202.pdf
	Identifier	ZNA-1994-49a-0202
	Volume	49

29	Author	H. H. Onda, A. Sasane, K. Miyagi, A. Ishikawa, Y. Mori	Requires cookie*
	Title	81Br NQR for Uncoordinated Br ions in trans-[CoBr2 (en)2] [H50 2]Br2 and trans-\CoBr2 (en)2] [D50 2]Br2
	Abstract	The temperature dependence of the 81Br NQR frequencies (vD) for uncoordinated Br-ions in trans-[CoBr2 (en)2] [D 5 0 2 ]Br2 (D) has been determined by a continuous-wave spectrometer. vD
	Reference	Z. Naturforsch. 49a, 209—212 (1994); received July 23 1993
	Published	1994
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	TEI-XML for	default:Reihe_A/49/ZNA-1994-49a-0209.pdf
	Identifier	ZNA-1994-49a-0209
	Volume	49

30	Author	H. Ideta, Ish Ih, Ra, V.G K Rish N An, Shi-Qi, HelmutP. Aulus3, AlarichW. Eiss3	Requires cookie*
	Title	Bromine NQR and Crystal Structures of Tetraanilinium Decabromotricadmate and 4-Methylpyridinium Tribromocadmate
	Abstract	The 7 9 , 8 1 Br NQR spectra of tetraanilinium decabromotricadmate (1) and 4-methylpyridinium tribromocadmate (2) were studied as function of temperature and their crystal structures were determined. (C6 H 5 N H 3)4 Cd3 Br10 (1): Space group D ^ -P b c a , Z = 4, a = 2507.8(7) pm, b = 1985.4(5)pm, c = 763.0(2)pm. Characteristic for the structure are trioctahedral units [Cd3 Br10] condensed to planes. Within the units the octahedra are face connected and further condensed to planes via common corners. Two types of hydrogen bonds are observed. The 81Br NQR lines with frequencies (MHz, 298 K) of 62.98, 52.59, 43.39, 41.82, and 40.71 are little temperature dependent with positive and negative coefficients. The wide frequency range of the NQR lines is reflected by the wide range of the intraionic distances, 263<d(B r-C d)/pm <300. (4-(CH3)C5 H4 NH)CdBr3 (2): C^h-P 2 Jn, Z = 4, a = 1228.8(5}pm, b= 1168.5(5)pm, c = 758.3(3)pm, /? = 95.30(1)°; the CdBrf ions are condensed to chains. The Br NQR spectrum is a triplet with frequencies (MHz, 298 K) of 66.01, 55.39, and 50.75. The temperature dependence is small, with positive and negative temperature coefficients. The distances rf(Cd-Br) are 256 pm (C d-B r(2)), 261 pm (C d -B r 1'), and 284 pm (C d-B r(3)) and in the chain [C dBr^Br1* and B r3) are bridging atoms. The relations between Br-NQR and crystal structures are discussed.
	Reference	Z. Naturforsch. 49a, 213—222 (1994); received July 23 1993
	Published	1994
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	Identifier	ZNA-1994-49a-0213
	Volume	49

31	Author	V. G. Krishnan, Shi-Qi Dou, Alarich Weiss	Requires cookie*
	Title	Tetraguanidium Hexabromocadmate, [C(NH2)3l4[CdBr6]. Crystal Structure and Bromine Nuclear Quadrupole Resonance
	Abstract	The 7 9 , 8 1 Br NQR spectra of tetraguanidinium hexabromocadmate, [C(NH2)3]4 [CdBr6] have been studied as a function of temperature from 77 K to 390 K and the crystal structure of the compound was determined at room temperature. The title compound crystallizes monoclinic, P2x/c, with four formula units in the unit cell, a = 839.2(3) pm, b = 1895.8(6) pm, c= 1527.4(5) pm, ß= 108.14(1)°. The anion [CdBr6]4e is an isolated octahedron, with bond lengths 275<d (C d -B r)/p m <281, and bond angles 8 8 <(B r-C d -B r)/° <95, slightly distorted by hydrogen bonds N -H • • • Br. The 81Br NQR sextet, in dependence from temperature, shows positive and negative temperature coefficients. At 77 K the 81Br NQR frequencies have been found between 42.42 MHz and 31.99 MHz; the 79Br NQR at the frequencies expected from the nuclear quadrupole moment ratio Q(7 9 B r)/g(8 1 Br). Relations between the 81Br NQR spectrum, the crystal structure, and the hydrogen bonds are discussed.
	Reference	Z. Naturforsch. 49a, 223—231 (1994); received October 1 1993
	Published	1994
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	TEI-XML for	default:Reihe_A/49/ZNA-1994-49a-0223.pdf
	Identifier	ZNA-1994-49a-0223
	Volume	49

32	Author	J. Pelzl, C. Dimitropoulos	Requires cookie*
	Title
	Abstract	Recent and novel data obtained from chlorine NQR measurements on natural and deuterated (NH4)2 MC16 compounds are discussed with special regard to the influence of the ammonium-ion dynamics on the structural stability of these crystals. The temperature dependence (4.2 K to 350 K) of the chlorine NOR frequency \ q and relaxation rates Tj-1 , T2-1 obtained from the natural ammonium salts of Sn, Pd, Os, Pb, Te, Se and from the deuterated salts of Sn, Te and Se are analysed. Slight deviations from the normal temperature behaviour of vQ and Tt~ 1 are found in Sn, Pd and Os compounds which stay cubic in the whole temperature range. The ammonium compounds of Pb and Te undergo a structural transformation between 80 K and 90 K from the cubic to a trigonal phase which is distinguished by the preservation of the single line spectrum of the chlorine NQR below rel. The observed divergence of Tl_ 1 at the transition point can be described in terms of a spin-phonon process in the presence of an overdamped soft mode. Deuteration of (N H 4)2 TeCl6 only slightly affects the transition of Tcl but leads to new structural changes at lower temperatures. Whereas the natural compound stays trigonal down to 4.2 K the deuterated crystal undergoes two additional structural transformations at Te 2 = 48 K and Tc3 = 28 K which are correlated with a slowing down of the deuteron motion. Approaching Tc2 from above, the spin-lattice relaxation rate and the spin-spin relaxation rate of the chlorine NQR exhibit distinct anomalies which are attributed to limited jumps of the octahedron in a shallow potential. The barrier height of this potential deduced from the chlorine NQR spin-lattice relaxation rate is 400 K. The transition at Tc2 is explained by the condensation in one minimum of this potential. At Tc3 a long range correlation is formed which is accompanied by a rotation of the octahedron about its fourfold axis. A similar mechanism is adopted for the transitions observed in (NH4)2 SeCl6 at Tc= 24 K and in (ND4)2 SeCl6 at Tc = 48 K.
	Reference	Z. Naturforsch. 49a, 232—246 (1994); received August 12 1993
	Published	1994
	Keywords	Nuclear quadrupole resonance, Structural phase transitions, Ammonium-ion dynam ics, Hexahalogenometallates, Critical behaviour
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	TEI-XML for	default:Reihe_A/49/ZNA-1994-49a-0232.pdf
	Identifier	ZNA-1994-49a-0232
	Volume	49

33	Author	Motoko Kenmotsu, Hisashi Honda, Hiroshi Ohki, Ryuichi Ikeda, Tomoki Erata, Akira Tasaki, Yoshihiro Furukawa	Requires cookie*
	Title	Ionic Dynamics in Plastic Crystal KNOz Studied by 39K and I5NNMR
	Abstract	The spin-lattice relaxation time of 39K N M R observed in the low-temperature phase (T <264.1 K) of K N 0 2 is explained by the quadrupole mechanism contributed from a newly found N O J m otion. The in-plane C 3 reorientation and the overvall N 0 2 rotation as well as the self-diffusion were shown in the intermediate phase (T < 314.7 K) and the high-temperature plastic phase (T < melting point: 710 K), respectively, by observing 39K and 15N N M R relaxation times and 1SN lineshapes.
	Reference	Z. Naturforsch. 49a, 247 (1994); received July 23 1993
	Published	1994
	Keywords	K e y words: Solid NM R, Q uadrupole relaxation, Plastic crystal, Phase transition, Chemical shift anisotropy
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	TEI-XML for	default:Reihe_A/49/ZNA-1994-49a-0247.pdf
	Identifier	ZNA-1994-49a-0247
	Volume	49

34	Author	Tetsuo Asaji, Hideshi Tomizawa, Ryuichi Ikeda	Requires cookie*
	Title	Structural Phase Transition of N,N-Dimethylnitramine as Studied by 14N Nuclear Quadrupole Resonance
	Abstract	The 14N nuclear quadrupole relaxation time and resonance frequencies v+, v_, and vd of N,N-dimethylnitramine were measured between 14 and 313 K. The frequency increase of v+ and v_ observed below Tc (108 K) is explained by the increase o f prc electrons in the am ino nitrogen caused by the deformation of the m olecular skelton, which is planar above Tc. The sharp Tip minima for v+ and v_ observed at Tc are attributed to the softening o f vibration modes on both sides of Tc. The fluctuation o f the nitrogen-hydrogen m agnetic dipolar interaction due to C H 3 reorientation was detected as a broad T'lQ minimum observed around 84 K. A logarithmic divergence of Tu31 observed on the high-temperature side o f Tc suggests the presence o f a diffusive or overdamped-type soft mode.
	Reference	Z. Naturforsch. 49a, 253 (1994); received August 10 1993
	Published	1994
	Keywords	M olecular crystal, Phase transition, Soft mode, NQ R, Spin-lattice relaxation
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	Identifier	ZNA-1994-49a-0253
	Volume	49

35	Author	K. Yamada, K. Isobe, T. Okuda, Y. Furukawa	Requires cookie*
	Title	Successive Phase Transitions and High Ionic Conductivity of Trichlorogermanate (II) Salts as Studied by 35C1 NQR and Powder X-Ray Diffraction
	Abstract	A series o f trichlorogermanate(II) salts (AG eCl3, A = Rb, Cs, C H 3N H 3, and (C H 3)4N) have been synthesized and characterized by 35C1 N Q R , 35C1 N M R , AC conductivity, DTA, and X-ray diffrac tion techniques. In the temperature range studied two, two, five, and four phases were confirmed for the Rb, Cs, C H 3N H 3, and (C H 3)4N salts, respectively. From the 35C1 N Q R and structural data, isolated pyramidal G eC l3 anions were recognized in the low temperature phases. With increasing temperature the relaxation times of the 35C1 N Q R decreased exponentially and the signals disap peared far below the melting point. This suggests that the reorientation of the anion about the pseudo three-fold axis is excited. With further increase in temperature, the ionic conductivity of C H 3N H 3G eC l3 and (C H 3)4N G eC l3 increased drastically at the phase transitions to their cubic perovskite phases (C H 3N H 3G eC l3: a = 10-1 S m -1 at 400 K, (C H 3)4N G eC l3: a = 5 x 10-2 S m _1 at 420 K). The mobile ion was confirmed to be the chloride ion by means of 35C1 N M R and X-ray diffraction.
	Reference	Z. Naturforsch. 49a, 258 (1994); received July 23 1993
	Published	1994
	Keywords	35C1 N Q R, 35C1 N M R, Ionic conductivity, Rietveld analysis, Phase transition
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	Identifier	ZNA-1994-49a-0258
	Volume	49

36	Author	Hirokazu Nakayama, Taro Eguchi, Nobuo Nakamura	Requires cookie*
	Title	Phase Transitions in 4,4'-Dichlorobenzophenone as Studied by 3SC1FT-NQR
	Abstract	The temperature dependence of 35C1 N Q R frequencies in 4,4'-dichlorobenzophenone was m ea sured between 9.3 and 372 K by the pulse Fourier-transform method. Successive phase transitions were observed at 189 and 194 K. Concerning these phase transitions, the curious thermal hysteresis phenom enon found in a previous N Q R experiment was not reproduced in the present study. It also follow s that N Q R indicates another phase transition around 220 K, although no thermal anom aly was detected there by DTA. Tentative explanations for these three phase transitions are presented in relation to the incommensurability between 189 and 220 K. In addition, a novel phase transition was found to occur at 331 K according to both DTA and 35C1 N Q R. A single N Q R line observed at room temperature splits into two com ponents above 331 K, suggesting that the symmetry above 331 K is lower than that at room temperature. This is the behavior o f re-entrant phase transition, and it reveals the quasi-continuous nature.
	Reference	Z. Naturforsch. 49a, 267 (1994); received August 21 1993
	Published	1994
	Keywords	35C1 N Q R, 4, 4'-dichlorobenzophenone, Phase transition, Incomm ensurate phase
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	Identifier	ZNA-1994-49a-0267
	Volume	49

37	Author	Haruo Niki, Hirotaka Odahara, Katsuji Tamaki, Masao Hashimoto	Requires cookie*
	Title	Inequivalent Reorientation of the Trichloromethyl Groups in l,4-Bis(TrichloromethyI) Benzene as Studied by Pulsed 35C1NQR
	Abstract	The temperature dependence of Ti of 35C1 N Q R o f the title com pound evidenced that the three crystallographically inequivalent CC13 groups have different potential barriers against reorientation (about 30, 36, and 42 kJ/mol). An intramolecular interaction between rc-electrons on the benzene ring and the C -C l bond is proposed to interpret the characteristic frequency splitting com m on to the 35C1 N Q R spectrum of each of the three inequivalent CC1? groups. The magnitude of T2 of each Cl atom is interpreted by intra-and intermolecular H • • • Cl interactions. It was found that only part of the temperature dependence of the N Q R frequency can be interpreted by reorientation.
	Reference	Z. Naturforsch. 49a, 273—2 (1994); received July 23 1993
	Published	1994
	Keywords	Chlorine NQ R, Spin lattice relaxation, Transeverse relaxation, M olecular structure
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	Identifier	ZNA-1994-49a-0273
	Volume	49

38	Author	Masao Hashimoto, Shuji Matsumoto, Masakazu Kunitomo, Haruo Niki, Hirotaka Odahara, Katsuji Tamaki	Requires cookie*
	Title	35C1 NQR Relaxation and Hydrogen Bond in Some Chloral Hemiacetals
	Abstract	The crystal structure of chloral ethylhemiacetal has been determined at 291 K: monoclinic, space group C f -P 2 lt Z = 2, a = 854.5(1), b = 594.0(3), c = 853.3(1) pm, ß = 108.30(2)°, R = 0.0962. A sharp decrease of the spin lattice relaxation time 7i found for the 35C1 N Q R o f the CC13 groups in chloral methyl-, ethyl-and n-heptylhemiacetals is attributed to the onset of reorientation of the group over a potential barrier o f ca. 39, 37, and 32 kJ/m ol, respectively. An unusual vs. 1/T curve with a 7i minimum superimposed on the sharp decrease of 7\ due to the reorientation was observed for each of the three Cl N Q R lines of nH p-C H . This phenom enon is tentatively ascribed to a fluctuation of EFG caused by jum ping m otion o f the hydrogen atom s in the OH groups.
	Reference	Z. Naturforsch. 49a, 279 (1994); received August 16 1993
	Published	1994
	Keywords	Crystal structure, Hydrogen bond, Chlorine N Q R, Spin lattice relaxation
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	Identifier	ZNA-1994-49a-0279
	Volume	49

39	Author	Keizo Horiuchi	Requires cookie*
	Title	35C1 NQR Spin-Lattice Relaxation Mechanism in Ni(H20 ) 6SnCl6 and M g(H20 ) 6SnCl6 Crystals
	Abstract	The 35C1 N Q R spin-lattice relaxation mechanism in isom orphous N i(H 20) 6SnCl6 and M g(H 20) 6SnCl6 crystals is reported. The spin-lattice relaxation time T1(j in the N i com pound is determined mainly by a paramagnetic relaxation. However, above ca. 400 K T1Q decreased rapidly and a log vs. T 1 curve was almost linear. This steep decrease of T1Q was explained by reorientational m otions of the anions with an activation energy o f 73 kJm ol" 1. In addition, a double minimum in Tin, which can be interpreted as arising from the fluctuation o f the electric field gradient (EFG) at the chlorine site caused by cationic thermal m otions, was observed around room temper ature. The temperature dependence of the 35C1 N Q R r iQ in the M g salt is re-analysed in the light of the EFG -m odulation effect caused by a 180° flip m otion of the H 20 molecules and an overall reorientational m otion of the [M g(H20) 6]2+ octahedral cations as a whole.
	Reference	Z. Naturforsch. 49a, 286 (1994); received O ctober 16 1993
	Published	1994
	Keywords	Complex com pounds, M olecular dynamics Nuclear relaxation, Nuclear quadrupole resonance Electric field gradient
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	Identifier	ZNA-1994-49a-0286
	Volume	49

40	Author	Mineyuki Hattori, Yoshito Onoda, Tomoki Erata, M. E. Smith, Bruker Analytische, M. Esstechnik, G. M. Bh, Masakazu Hattori, Hiroshi Ohki, Ryuichi Ikeda	Requires cookie*
	Title	Ionic motion and Disordered Structure in the Rotator Phase of Butylammonium Chloride Studied by Temperature Dependences of 35C1 and 2HNMR
	Abstract	Temperature dependences o f 35C1 and 2H quadrupole coupling constants and 35C1 N M R spin-lat tice relaxation times in polycrystalline samples were measured in the rotator phase of the butylam m onium chlorides C 4H 9N H 3C1 and C4H 9N D 3C1, obtainable above the phase transition tempera ture o f 241 K. A rapid decrease o f the quadrupole coupling constants of both nuclei upon heating is attributed to increasing dynam ic disorder formed around the polar head. The presence of self-dif-fussion o f C P ions was revealed from the spin-spin relaxation time and resonance line-width in single crystals, and confirmed by measuring the dc electrical conductivity.
	Reference	Z. Naturforsch. 49a, 291 (1994); received July 23 1993
	Published	1994
	Keywords	Solid N M R, Quadrupole coupling constant, Spin-lattice relaxation time, Self-diffusion, Rotator phase
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	Identifier	ZNA-1994-49a-0291
	Volume	49

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