Analysis of the effect of the electronic structure of the Cl atom in complexes of chlorides of group IV elements on Cl NQR frequency and asymmetry parameter

Analysis of changes in ³⁵Cl NQR frequency of complexes MCl₄.L and MCl₄.2L for M = Si, Ge, Sn and Ti was performed. The population of the atomic orbitals was calculated by the quantum chemistry methods PM3 and INDO. The results provided an explanation of the changes in ³⁵Cl NQR frequency and the asymmetry parameter upon complex formation. In the complexes of non-transition elements, a decrease in ³⁵Cl NQR frequency is first of all related to increasing population of p_z orbitals on Cl atoms. In the complexes of Ti, the increase in ³⁵Cl NQR frequency depends on a decrease in the p_π to d_π electron density transfer.     

X-ray fluorescent spectroscopy study of the charge state of heteroatoms in organic compounds of third row elements. 7. Thiocyanates and isothiocyanates

We propose an x-ray spectral criterion as a characteristic of organic and inorganic thiocyanates and isothiocyanates. We establish the lack of interaction between the level of the unshared electron pair of sulfur and the _cC-orbitals in thiocyanates.Translated from Izvestiya Akademii Nauk SSSR, Seriya, Khimicheskaya, No. 11, pp. 2519–2521, November, 1989.     

Intramolecular noncovalent interactions: Bis(toluene)chromium(0) conformers

The structure of trans- and cis-conformers of bis(toluene)chromium(0) and the intramolecular interactions in them are studied by means of MP2 and density functional theory along with topological and NBO analyses. It was concluded for the first time that the locations of two hydrogen atoms of each methyl group between the phenyl ring planes in the most stable cis-conformer of bis(toluene)chromium(0) are largely determined by the stabilizing interactions of methyl C-H bonds and their hydrogen atoms with the metal atom and chromium-carbon bonds. It was concluded from the obtained data that the C-H...Cr contacts in the studied conformers should be considered as hydrogen bonds rather than agostic interactions. Contrary to the existing conception of the quantum theory of atoms in molecules, repulsive interaction is shown to occur between the pairs of hydrogen atoms of the two methyl groups in bis(toluene)chromium(0) cis-conformers rather than the stabilizing hydrogen-hydrogen interactions.     

Ligand effect on chlorine electron density distribution in titanium tetrachloride complexes

C1 Kα line shifts and ³⁵Cl NQR frequencies have been measured for series of titanium tetrachloride complexes. Nonempirical calculations of corresponding free ligands have been carried out on the MP2/6‐31G* level. Dependencies of the experimental data obtained on experimental and calculated parameters of ligand donor ability have been analyzed. It is shown that the electron density on acceptor chlorine atoms and the electric field gradient on their nuclei are determined at first by the polarizing effect of the ligand. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:177–181, 2000     

Halogenating and Nitrating Activity of Reagents Based on Sodium Nitrate and Alkali Metal Halides in Acetic Acid

Alkali metal halides NaF, KCl, and KBr sharply enhance the nitrating activity of sodium nitrate in acetic acid with respect to 9-methylcarbazole. In the presence of KI and KBr, both nitration and halogenation of the substrate occurs, while KCl and NaF promote only the nitration process. The results may be interpreted in terms of formation of the corresponding nitryl halides XNO2 (X = F, Cl, Br, I) whose structure and reactivity were examined in the framework of the density functional theory (DFT B3LYP/3-21G*).     

Analysis of the effect of the electronic structure of the Cl atom in complexes of chlorides of group IV elements on Cl NQR frequency and asymmetry parameter

Analysis of changes in ³⁵Cl NQR frequency of complexes MCl₄.L and MCl₄.2L for M = Si, Ge, Sn and Ti was performed. The population of the atomic orbitals was calculated by the quantum chemistry methods PM3 and INDO. The results provided an explanation of the changes in ³⁵Cl NQR frequency and the asymmetry parameter upon complex formation. In the complexes of non-transition elements, a decrease in ³⁵C1 NQR frequency is first of all related to increasing population of p_z orbitals on Cl atoms. In the complexes of Ti, the increase in ³⁵Cl NQR frequency depends on a decrease in the p_π to d_π electron density transfer.