ZfN: Search Results

1	Author	A. Ishikawa, A. Sasane, Y. Hirakawa, Y. Mori	Requires cookie*
	Title	Motion of Water Molecules and Hydrogen Bonds in Zinc Hexachlorostannate (IV) Hexahydrate as Studied by *H NMR and 35 C1 NQR
	Abstract	The *H NMR spin-lattice relaxation time 7\, 35 C1 NQR frequency VQ, and 35 C1 NQR spin-lattice relaxation time 7\ Q of [Zn(H 2 0) 6 ] [SnCl 6 ] (zinc hexachlorostannate(IV) hexahydrate) have been measured at temperatures between 77 and 350 K. The NQR spin echo signal with Vq— 15.689 MHz at 77 K showed a positive temperature coefficient attributable to O-H-Cl type H-bonds in the crystal. v Q at 77 K is strongly correlated with the electronegativity Xm of the metal M in the series of stannates [M(H 2 0) 6 ] [SnCl 6 ] (M = Mg, Ca, Mn, Co, Ni, Zn). A 7\ minimum observed for the Zn salt is ascribed to 180° flips of water molecules with an activation energy of 20 kJ mol -1 . The motion is influenced by repulsive forces among the water molecules within a cation rather than by attractive forces between the H-bonded H and CI atoms. 7\q proved to be mainly governed by lattice vibrations, weakly modulated by the fluctuating electric field gradient caused by the 180° flip motions.
	Reference	Z. Naturforsch. 51a, 693—697 (1996); received October 10 1995
	Published	1996
	Keywords	'H NMR spin-lattice relaxation, 35 C1 NQR frequency, 35 C1 NQR spin-lattice relaxation, H-bonding, Electronegativity
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	TEI-XML for	default:Reihe_A/51/ZNA-1996-51a-0693.pdf
	Identifier	ZNA-1996-51a-0693
	Volume	51

2	Author	A. Ishikawa, M. Kurasawa, S. Kitahara, A. Sasane, N. Kojima, R. Ikeda	Requires cookie*
	Title	A 35 C1 NQR Study on CS 2 [AU I C1 2 ] [Au m Cl 4 ]
	Abstract	A pair of 35 C1 NQR spin echo signals has been observed for the mixed valence complex Cs 2 [Au'Cl 2 ] [Au'^C^] between 77 and 243 K. At 77 K, two resonance lines with the half widths Av Q ~ 50 kHz were located at v Q1 = 17.28 MHz for the Au'-Cl chlorine and at v Q2 = 27.10 MHz for the Au m -Cl chlorine in accordance with the crystal structure. The chlorine ionic characters of the Au'-Cl and Au'"-Cl bonds are estimated as 0.63 and 0.42, respectively. The central gold atom carries a fractional protonic charge of 0.26 in [AU'C1 2 ]~ and 0.68 in [Au"'Cl 4 p. The charge distributions in the complex anions differ in-significantly from those in the isolated [AUC1 2 ]~ and [AUC1 4 ]" for ordinary complexes, indicating that the charge transfer interactions between the anions are weak in the mixed valence complex. The ob-served linear temperature dependencies of Vg and log T lQ are well explained by the lattice vibration. When the temperature was increased from 77 K, the resonance lines became gradually weak without changing AV q and immeasurable above 215 K. ESR spectra taken at various temperatures revealed the presence of paramagnetic sites of ca. 5x 10 2<) mol -1 arising from Au(II). The small but finite concen-tration of Au(II) or some other reason should be responsible for the fade out phenomenon and the large Avq observed.
	Reference	Z. Naturforsch. 53a, 590—594 (1998); received December 31 1997
	Published	1998
	Keywords	35 C1 NQR Frequency, 35 C1 NQR Spin-lattice Relaxation, Mixed Valence Gold Complex, Charge Transfer Interaction, ESR
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	TEI-XML for	default:Reihe_A/53/ZNA-1998-53a-0590.pdf
	Identifier	ZNA-1998-53a-0590
	Volume	53

3	Author	A. Sasane, S. Fukumitsu, Y. Mori, D. Nakamura	Requires cookie*
	Title	Temperature Dependence Studies of 3 5 CI NQR Frequencies in Magnesium and Nickel Hexachlorotellurate(IV) Hexahydrates and Nickel Hexachloroiridate(IV) Hexahydrate
	Abstract	The 35 C1 NQR frequencies in MgTeCl 6 • 6 H 2 0, NiTeCl 6 • 6 H 2 0, and NiIrCl 6 • 6 H 2 0 have been determined at various temperatures. These compounds form rhombohedral crystals with the space group R3, showing a single resonance line. The 35 C1 NQR frequencies of the Te(IV) complexes exhibit an unusual positive temperature coefficient. The deuterated analogs of the Te(IV) complexes show a small frequency shift at 77 K. These results are interpreted by the presene of O-H • • • CI type weak H-bonds. The resonance frequency of the Ir(IV) complex versus temperature curve shows a minimum and a maximum. This unusual temperature dependence is mainly explained by the same type of the H-bond as existing in the Te(IV) complexes. The 7r-bond formation between Ir and CI atoms is also partly responsible for the unusual temperature dependence.
	Reference	Z. Naturforsch. 45a, 303—306 (1990); received October 21 1989
	Published	1990
	Keywords	35 C1 NQR frequency, Positive temperature coefficient, H-bond, rc-bond, 1 H-2 H isotope effect
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	TEI-XML for	default:Reihe_A/45/ZNA-1990-45a-0303.pdf
	Identifier	ZNA-1990-45a-0303
	Volume	45

4	Author	ValentinP. Feshin, ElenaV. Feshina	Requires cookie*
	Title	Correlation between the 35 CI NQR Parameters of Chloro-containing Organic and Organometallic Compounds and the Results of ab initio Calculations
	Abstract	The results of comparison of experimental 35 C1 NQR parameters for a great number of organic and organometallic compounds and estimated ones using ab initio calculations at the RHF/6-31G(d) level were systematized. The NQR frequency changes on going from one compound to another depend, in general, on the changes of populations of the CI atom p"-orbitals in these compounds and, first of all, of populations of their less diffuse parts.
	Reference	Z. Naturforsch. 55a, 555—559 (2000); received December 15 1999
	Published	2000
	Keywords	ab initio Calculations, p-orbital Populations, 35 C1 NQR Frequency, Asymmetry Parameter, Chloro-containing Organic and Organometallic Compounds
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	TEI-XML for	default:Reihe_A/55/ZNA-2000-55a-0555.pdf
	Identifier	ZNA-2000-55a-0555
	Volume	55