Refinement of the structural parameters of potassium metaborate in the gas phase

1984 ◽  
Vol 25 (3) ◽  
pp. 492-493 ◽  
Author(s):  
Yu. S. Ezhov ◽  
S. M. Tolmachev
Keyword(s):  
Gas Phase ◽  
Structural Parameters

Microwave Spectra and Gas-Phase Structural Parameters of Bis(η5-cyclopentadienyl)tungsten Dihydride

2007 ◽  
Vol 26 (8) ◽  
pp. 2070-2076 ◽  
Author(s):  
Brandon S. Tackett ◽  
Chandana Karunatilaka ◽  
Adam M. Daly ◽  
Stephen G. Kukolich
Keyword(s):  
Gas Phase ◽  
Structural Parameters ◽  
Microwave Spectra

Analysis of Decisive Structural Parameters and Acidic Property of Zeolites for Gas‐Phase Alkylation of Benzene with Ethylene

2021 ◽  
Vol 6 (42) ◽  
pp. 11779-11787
Author(s):  
Yunping Zhai ◽  
Youju Wang ◽  
Junwen Chen ◽  
Shihang Liang ◽  
Yongrui Wang ◽  
...  
Keyword(s):  
Gas Phase ◽  
Structural Parameters ◽  
Acidic Property ◽  
Alkylation Of Benzene

scholarly journals Bar effect on gas-phase abundance gradients. I. Data sample and chemical abundances

2020 ◽  
Vol 500 (2) ◽  
pp. 2359-2379 ◽  
Author(s):  
A Zurita ◽  
E Florido ◽  
F Bresolin ◽  
E Pérez-Montero ◽  
I Pérez
Keyword(s):  
Emission Line ◽  
Gas Phase ◽  
Direct Method ◽  
Structural Parameters ◽  
Companion Paper ◽  
Strong Line ◽  
H Ii Regions ◽  
Chemical Abundances ◽  
The Galaxy ◽  
H Ii Region

ABSTRACT Studies of gas-phase radial metallicity profiles in spirals published in the last decade have diminished the importance of galactic bars as agents that mix and flatten the profiles, contradicting results obtained in the 1990s. We have collected a large sample of 2831 published H ii region emission-line fluxes in 51 nearby galaxies, including objects both with and without the presence of a bar, with the aim of revisiting the issue of whether bars affect the radial metal distribution in spirals. In this first paper of a series of two, we present the galaxy and the H ii region samples. The methodology is homogeneous for the whole data sample and includes the derivation of H ii region chemical abundances, structural parameters of bars and discs, galactocentric distances, and radial abundance profiles. We have obtained O/H and N/O abundance ratios from the Te-based (direct) method for a subsample of 610 regions, and from a variety of strong-line methods for the whole H ii region sample. The strong-line methods have been evaluated in relation to the Te-based one from both a comparison of the derived O/H and N/O abundances for individual H ii regions and a comparison of the abundance gradients derived from both methodologies. The median value and the standard deviation of the gradient distributions depend on the abundance method, and those based on the O3N2 indicator tend to flatten the steepest profiles, reducing the range of observed gradients. A detailed analysis and discussion of the derived O/H and N/O radial abundance gradients and y-intercepts for barred and unbarred galaxies is presented in the companion Paper II. The whole H ii region catalogue including emission-line fluxes, positions, and derived abundances is made publicly available on the CDS VizieR facility, together with the radial abundance gradients for all galaxies.

Theoretical analysis of ammoniaborane and alkylammoniaborane at the solid state

2017 ◽  
Author(s):  
Mariano Méndez Chávez
Keyword(s):  
Density Functional Theory ◽  
Solid State ◽  
Theoretical Analysis ◽  
Gas Phase ◽  
Density Functional ◽  
Structural Parameters ◽  
Ammonia Borane ◽  
Functional Theory ◽  
The Density Functional Theory

This work deals with a benchmark for the calculation of the structural parameters of ammonia-borane and alkylammonia-borane at the solid state, using hybrid and GGA functionals in the framework of the Density Functional Theory as well as the use of Grimme's empirical dispersion. A comparison for some dimers of the aforementioned species, calculated at the gas-phase at the level MP2/aug-cc-pVTZ is discussed.

Intramolecular and Liquid Structures of Tetramethylurea Studied by Means of X-Ray Diffraction

1992 ◽  
Vol 47 (9) ◽  
pp. 1003-1010 ◽  
Author(s):  
T. Radnai ◽  
H. Ohtaki
Keyword(s):  
Gas Phase ◽  
Random Distribution ◽  
Structural Parameters ◽  
Diffraction Method ◽  
Methyl Groups ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molecular Ordering ◽  
Amide Derivatives ◽  
Good Agreement

Abstract The intramolecular and liquid structures of tetramethylurea (TMU) were investigated by the liquid x-ray diffraction method. It is confirmed that in the liquid state the four methyl groups are out of the plane which is constructed by the O, C, and the two N atoms, the molecular structure being similar to what had been found in the gas phase. All structural parameters are in good agreement with those of TMU determined in the gas phase and with those of amide derivatives in the liquid phase. The liquid is characterized by a random distribution of molecules as predominant, but a weak molecular ordering characterized by approximately two intermolecular nonbonding Me ··· O distances at 340 pm is proposed

Microwave Spectra and Gas Phase Structural Parameters forN-Hydroxypyridine-2(1H)-thione

2011 ◽  
Vol 115 (50) ◽  
pp. 14526-14530 ◽  
Author(s):  
Adam M. Daly ◽  
Erik G. Mitchell ◽  
Daniel A. Sanchez ◽  
Eric Block ◽  
Stephen G. Kukolich
Keyword(s):  
Gas Phase ◽  
Structural Parameters ◽  
Microwave Spectra

An Electron-Diffraction Investigation of the Molecular Structure of Toluene

1977 ◽  
Vol 32 (9) ◽  
pp. 1063-1064 ◽  
Author(s):  
Takao Iijima
Keyword(s):  
Molecular Structure ◽  
Electron Diffraction ◽  
Gas Phase ◽  
Structural Parameters ◽  
Electron Diffraction Investigation ◽  
Gas Phase Electron Diffraction

AbstractThe structural parameters of toluene have been deter­ mined by gas-phase electron diffraction. The bond distances in rg are as follows: C-C(ring) 1.399± 0.002 Å, C-C (me­thyl) 1.524± 0.007 Å, C -H(ring) 1.11 ± 0.01 Å. and C-H-(methyl) 1.10 ±0.02 Å.

scholarly journals MOLECULAR STRUCTURE OF TRYPTOPHAN: GAS PHASE ELECTRON DIFFRACTION AND QUANTUM-CHEMICAL STUDIES

2020 ◽  
Vol 63 (3) ◽  
pp. 37-45
Author(s):  
Valeriya V. Dunaeva ◽  
Georgiy V. Girichev ◽  
Nina I. Giricheva
Keyword(s):  
Molecular Structure ◽  
Amino Acids ◽  
Electron Diffraction ◽  
Gas Phase ◽  
Quantum Chemical ◽  
Structural Parameters ◽  
Electron Diffraction Data ◽  
Geometrical Parameters ◽  
Intramolecular Hydrogen ◽  
Gas Phase Electron Diffraction

The molecular structure and conformational properties of tryptophan have been investigated by gas-phase electron diffraction and theoretical methods. Quantum chemical calculations realized by program Gaussian 03 (B3LYP/cc-pVTZ) have been predicted the existence of six conformers at the temperature of experiment (T = 495 K). The ability of gas-phase electron diffraction method to distinguish the structure of conformers was estimated theoretically. Conformers have different orientations of carboxylic and amine group, backbone and indole fragment to each other. These conformers can be divided on two groups: distinguishable parameters (with different torsion angle C(OOH)-C(HNH2)-C(H2)-C(ind)) and weekly distinguishable ones (with different torsion angles H-N-C-C and H-O-C-C) by gas-phase electron diffraction. The molecular parameters of the conformers were determined. The conformers have intramolecular hydrogen bonding of the H2N···HO. The analysis of the gas-phase electron diffraction data have been carried out assuming the saturated vapor of tryptophan at T = 495 K consists of mixture at least of two conformers with lowest energy. It was shown that optimal ratio between conformers I : II was 50 : 50, respectively. The geometrical parameters of amino acids molecules (glycine, alanine, tryptophan) obtained by gas-phase electron diffraction were compared. The influence of the intramolecular hydrogen bond was established onto the structural parameters of the backbone of the above amino acids molecules.

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