Raman spectroscopy study of powdered [Ni(NH₃)₆] X₂ compounds

Abstract

Ten out of eleven Raman active modes were detected in [Ni(NH&] XZ powders, apart from internal modes of the X-ions. The Raman active lattice mode happens to agree fairly well with the predictions of a model based on the electrostatic potential field of point charges. The X=Cl compound showed evidence of losing ammonia during irradiation with the laser beam. Two modes (the N-Ni-N angle deformation and the lattice vibration) are especially sensitive to the NH3-vacancies thus created.

Distortion of Crystal Structures of Some CoIII Ammine Complexes. I. Distortion of Crystal Structure of [Co(NH3)5NO2]Cl(NO3) on Cooling

“…Hydrogen bonds may act as 'joints', which account for large, anisotropic and reversible distortions of the crystal structure. They are known to play a central role in the lattice dynamics and structural transformations in complex ammines of transition metals (Bates, Hughes & Somerford, 1983;Elgsaeter & Svare, 1970;Essmann, Fischer & Vogt, 1996;Hoser, Prandl, Schiebel & Heger, 1990;Janik, Janik & Janik, 1978). At the same time, the anisotropy of structural distortion of the same structure even at two scalar isotropic actions (temperature and pressure) is different.…”

Neutronenpulverdiffraktionsmessungen an [Zn(ND3)4]I2 bei 1,5 K, 10 K und 293 K: Wasserstoff‐Brückenbindungen und Bewegungen von ND3‐Molekülen

“…Bei 1,5 K liegen Bindungslangen d(N-D) von 0,996(9) A und 1,007 ( (6) A, 0,980 (7) A, 1,007 (7) A) sind im Rahmen der MelJgenauigkeit, wie schon zuvor, durchaus erwartungsgemafi. Neben zwei 2-Zentren- (4); 10,3381(5)] 7,5239(6) [7,3960(2); 7,3935(4)], 13,088(1) [12,9731(4); 12,9695 (6)] 0,006 (2) [0,057(1);0,020 (2)] 0,43 (3) [0,47(1); 0,49(2)1 -0,49 (2) [ -0,24(1); -0,28 (2)] 0,180 (5) [0,114 (3); 0,134 (4)] Thompson-Cox-Hastings pseudo-Voigt 0,084 (3) [0,128(2); 0,106 (3)] 0,033 (7) [0,077(4); 0,062 (7)] 0,037 (2) (2)' 0,336(1) 9,4(3)' 0,0384(5) 0,3392 (3) 2,66 (5) o;ssoo(sj 0,0367(7) 0,3416 (5)…”

“…(0,991(5) A 5 d(N-D) I 1,007(9) A, 108,6(5)' I H-N-H I 113,0(6)') den Erwartungen. Die D -* * I-Abstande von 2,91 A und 2,79 .…”

Phase Transitions in [M(NH3)6] (XY4)2 Compounds

“…I n order to describe the structure of phase 11, one should know not only the displacement vector of all the groups of atoms in phase I, but also their equilibrium positions and orientations from which these displacements are measured. I n the hexarnine complexes these data are known except for the anion groups which are expected t o perform a kind of stochastic rotational motion [6,8], and therefore their orientational equilibrium positions are not specified. However, the site symmetry a t (f, $, g) and…”

“…This concerns also the infrared-active lattice mode T1, which involves a combined translational motion of cations and anions. The Raman spectra of N H P and MHP give evidence for broadening of the internal modes I3 (463 cm-l) and T, (625 cm-1) of (C10,)ions in the cubic phase I [6,8]. I n phase I1 the mode E narrows, and the mode T, splits into two asymmetric peaks.…”