| | 1 | 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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| default:Reihe_A/49/ZNA-1994-49a-0185.pdf | | | | Identifier
| ZNA-1994-49a-0185 | | | | Volume
| 49 | |
| 2 | Author
| Jacek Zaleski | Requires cookie* | | | Title
| Crystal Structure and Phase Transitions of [C(NH2)3]3Sb2C l9 * 0.9 H 20 A dam Pietraszko | | | | Abstract
| The room temperature structure of [C(NH2)3]3Sb2C l9 ■ 0.9 H 20 (GNCA) was solved. It crystal lizes in the monoclinic C2/c space group with a = 15.275, b = 8.794, c = 17.904 (in Ä), ß = 96.40°, V = 2390 Ä 3, Z = 4. Refinement of the atomic parameters by a least squares methods gave R = 0.042, wR = 0.039 for 1958 reflections with F>4ct(F). The structure consists of polyanionic (Sb2Cl|_)n layers built of deformed corner connected SbX^-octahedra. Two crystallographically inequivalent guanidinium cations are present, one situated between polyanionic layers, the other one together with a disordered water molecule inside cavities formed by polyanions. Temperature X-ray scattering experiments together with DSC studies were carried out above room temperature. Temperature dependence of the lattice parameters between 300 K and 380 K was determined and a phase transition of mixed order at 364 K was revealed. | | | |
Reference
| Z. Naturforsch. 49a, 895—901 (1994); received June 7 1994 | | | |
Published
| 1994 | | | |
Keywords
| Guanidinium, Chloroantimonate, Crystal structure, Phase transition, DSC | | | |
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| default:Reihe_A/49/ZNA-1994-49a-0895.pdf | | | | Identifier
| ZNA-1994-49a-0895 | | | | Volume
| 49 | |
| 3 | 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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| default:Reihe_A/49/ZNA-1994-49a-0193.pdf | | | | Identifier
| ZNA-1994-49a-0193 | | | | Volume
| 49 | |
| 4 | 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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| default:Reihe_A/49/ZNA-1994-49a-0279.pdf | | | | Identifier
| ZNA-1994-49a-0279 | | | | Volume
| 49 | |
| 5 | Author
| Hiroyuki Ishida, Yoshihiro Kubozono, Setsuo Kashino, Ryuichi Ikeda | Requires cookie* | | | Title
| Crystal Structure of Trimethylammonium Perchlorate in Three Solid Phases Including the Ionic Plastic Phase Obtainable above 480 K | | | | Abstract
| The crystal structures of (CH3)3NHC104 in three solid phases were studied by X-ray diffraction techniques. X-ray powder patterns taken at ca. 500 and 445 K revealed that the plastic phase (Phase I) attainable above 480 K crystallizes in a CsCl-type cubic structure with a = 5.845 (1) A, Z = 1, V = 199.7 (2) Ä3, and Dx = 1.327 gem -3, while Phase II, stable between 480 and 396 K, forms a tetragonal structure with a = 9.912 (4), c = 7.01 (2) Ä, Z = 4, V = 689 (3) A3, and Dx = 1.54 gem -3. The room temperature phase (Phase III) was studied by single crystal X-ray diffraction and found to form a monoclinic lattice with space group P2X , a = 5.749(1), b = 8.670(1), c = 7.5585 (9) A, ß = 102.66 (1)°, Z = 2, V = 367.6 (2) A , and Dx= 1.441 g em -3. Thermal measurements, differential thermal analysis and differential scanning calorimetry, were carried out on these solid phases, and the obtained results were compared with those observed for (CH3)3NHBF4. | | | |
Reference
| Z. Naturforsch. 49a, 723—726 (1994); received March 12 1994 | | | |
Published
| 1994 | | | |
Keywords
| Crystal structure, X-ray diffraction, Thermal measurements, Ionic plastic phase | | | |
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| default:Reihe_A/49/ZNA-1994-49a-0723.pdf | | | | Identifier
| ZNA-1994-49a-0723 | | | | Volume
| 49 | |
| 6 | 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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| default:Reihe_A/49/ZNA-1994-49a-0202.pdf | | | | Identifier
| ZNA-1994-49a-0202 | | | | Volume
| 49 | |
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