using ab initio calculations, the hydrogen desorption from magnesium hydride (mgh2) was studied. we presented the calculated nuclear quadrupole coupling constants (nqccs) of hydrogen atom in various systems of mgh2. the effect of interactions of some metal atoms as well as boron atom with mgh2 host matrix; (mgh2+m) nanostructures (m=al, ti, v, fe, ni and b); were studied and 2h-nqccs were calcu...

Bonding models for silicates are assessed in relation to the local environment of oxygen, as determined by analysis of the oxygen17 nuclear quadrupole coupling constants (NQCC), using Townes-Dailey methods. The experimental NQCC of the silica polymorph low cristobalite is indicative of covalent charge transfer from the oxygen lone pairs to silicon and is consistent with Pauling’s (d-p) a-bondin...

Ab initio calculations of electric field gradients (EFG) and conversion to nuclear quadrupole coupling constants (NQCC) are described, with particular reference to N and l 0 , ' 'B . The correlation of EFG and NQCC for a series of boranes leads to the value 8.32 MHz/a.u. (0.0354 barn) for Q( n B). The structural variations of these microwave and single molecule calculations of 10, n B NQCC are ...

The electronic structures and the electrostatic potential of some amino derivatives of adamantane have been studied using the density functional theory. The partial atomic charges and nuclear quadrupole coupling constants (NQCC) of 14N nucleus of the considered molecules have been reported. The partial atomic charges are calculated with two methods for 14N nucleus: Mulliken charges and natural ...

We report a 67Zn nuclear magnetic resonance (NMR) study of compounds containing zinc ions coordinated by oxygen, nitrogen, and sulfur ligands. New information concerning 67Zn nuclear quadrupole coupling constants (NQCC) and chemical shift was obtained from magic-angle spinning (MAS) spectra of solid compounds containing both natural abundance and enriched 67Zn isotopes. Rapid ligand exchange pr...

In our first two papers on 14N nuclear quadrupole coupling constants (NQCC, Xij) [U 2], we showed that double zeta (DZ) ab initio molecular orbital calculations using a Huzinaga/Dunning 9s5p/4s basis [3] gave good linear correlations between the experimental microwave (MW) NQCC and the cal­ culated electric field gradients (EFG, <?,,) for a range of heterocyclic and other organic molecules. Fun...

The aerial parts of Tephrosia carrollii afforded two chromene chalcones. Their structures and stereochemistry were established by spectroscopic methods. The structure of oaxacacin was revised and confirmed by X-ray diffraction. In this paper, we describe the isolation of the chalcone known as "oaxacacin" and the new chalcone named epoxyobovatachalcone. The compound der. oaxacacin was found to b...

Poliovirus type 2 Sabin mutants were selected for drug resistance and dependence by plating on HeLa cell monolayers in the presence of 3(2H)-isoflavene, a compound related to dichloroflavan, which prevents the shut-off of host translation and poliovirus RNA and protein synthesis. The drug-resistant mutants grew equally well in the presence and in the absence of the drug, while the drug-dependen...

The dependence of the nuclear quadrupole coupling constants (NQCC) on the interaction between electrons and a nucleus of finite size is theoretically analyzed. A deviation of the ratio of the NQCCs obtained from two different isotopomers of a molecule from the ratio of the corresponding bare nuclear electric quadrupole moments, known as quadrupole anomaly, is interpreted in terms of the logarit...