The differences between thermal and vibrational properties of [Ni(NH 3 ) 4 ](ReO 4 ) 2 and [Ni(NH 3 ) 6 ] (ReO 4 ) 2 are reported. The differential scanning calorimetry revealed that tetraamminenickel(II) perrhenate exhibits, in the temperature range of 300-140 K, one phase transition at ca. T c h = 188 K (on heating) and T c c = 185 K (on cooling). In the case of hexaamminenickel(II) perrhenate, no phase transition was observed in the same temperature region. Thermogravimetric measurements showed that the decomposition proceeds in the two main stages. In the first stage, a complete deammination takes place and next Re 2 O 7 is released. TG measurements showed that NH 3 molecules are not equivalently bonded to central atom. The final and intermediate products of decomposition were analysed by means of infrared spectroscopy. The final product of thermal decomposition of both compounds is nickel(II) oxide. The analysis of far infrared spectra revealed that anions in [Ni(NH 3 ) 6 ](ReO 4 ) 2 have disturbed tetrahedral symmetry, whereas in [Ni(NH 3 ) 4 ](ReO 4 ) 2 they seem to form polymeric chains. The variation of the activation energies of the deammination and decomposition steps of [Ni(NH 3 ) 6 ](ReO 4 ) 2 was calculated through the model-free isoconversional Kissinger-Akahira-Sunose method and model-free Kissinger method. Infrared spectra were calculated by the DFT method and quite a good agreement with the experimental data was obtained.

No abstract

This paper dwells on the synthesis and diverse studies of cyclically arranged hydrogen bridges in tris-hydroxy aryl Schiff bases. Experimental (IINS, IR, Raman and X-ray) and theoretical (CPMD, DFTP and DFT) studies of tris-hydroxy aryl Schiff bases have been performed in the solid state.

No abstract

The synthesis, crystal structures, spectroscopic characterization, and comprehensive quantum-chemical calculations for a novel series of anion-π hybrid salts (XPh ) [M(CN) ][HAT(CN) ]⋅3 MeCN (X=P, M=Ni (1), Pd (3), Pt (5); X=As, M=Ni (2), Pd (4), Pt (6); HAT(CN) =1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile) are presented. The systems comprise 1D {[M(CN) ] ;[HAT(CN) ]} stacks, in which the electron-rich metal complexes adjust their orientation to match the electron-deficient areas of HAT(CN) . Electronic charge-transfer interactions along the stacks result in polarization of electron density within HAT(CN) and in perturbations along the {[M(CN) ] ;[HAT(CN) ]} contacts. Electronic structure analysis suggests, for example, a relocation of 0.1-0.2 e per molecule from [M(CN) ] to HAT(CN) and anion-π interaction energies of around -65 kcal mol . A reversible structural single-crystal-to-single-crystal transformation, through desolvation/resolvation processes in the solid state, is also reported and a scheme for the formation of anion-π [M(CN) ] /HAT(CN) adducts in MeCN is proposed.

No abstract

No abstract

No abstract