Optimized geometries, vibrational frequencies, and thermochemical properties of mixed boron- and nitrogen-containing three-membered rings

2007 ◽  
Vol 806 (1-3) ◽  
pp. 113-120 ◽  
Author(s):  
Ryan M. Richard ◽  
David W. Ball
Keyword(s):  
Vibrational Frequencies ◽  
Thermochemical Properties ◽  
Optimized Geometries

Computational investigation of isomeric and conformeric structures of methyl iodoperoxide

2005 ◽  
Vol 83 (1) ◽  
pp. 9-15 ◽  
Author(s):  
Evangelos Drougas ◽  
Agnie M Kosmas
Keyword(s):  
Electronic Structure ◽  
Single Point ◽  
Transition States ◽  
Vibrational Frequencies ◽  
Basis Sets ◽  
Quantum Mechanical ◽  
Energy Structure ◽  
Computational Investigation ◽  
Electronic Structure Methods ◽  
Optimized Geometries

Quantum mechanical electronic structure methods are employed to investigate the isomeric and conformeric stuctures of methyl iodoperoxide. Optimized geometries and harmonic vibrational frequencies are calculated at the MP2 level of theory using two types of basis sets, the 6-311G(d,p) for all atoms and the 6-311G(d,p) combined with the LANL2DZ relativistic ECP procedure for iodine. Refinement of the energetics has been accomplished by performing single-point CCSD(T) calculations. Five isomers were determined in total among which iodomethyl hydroperoxide (ICH2OOH) is found to be the lowest energy structure. Conformational barriers and transition states that connect the isomeric forms have been characterized.Key words: methyl iodoperoxide, isomers, conformers.

scholarly journals Cordination Compound of Dimethyltin(IV) with N,N,N’N’-Tetraethylethylenediamine: Speciation and Theoretical approach

2020 ◽  
Vol 64 (2) ◽  
Author(s):  
Safaa Said Hassan ◽  
Mohamed Mohamed Shoukry ◽  
Abdel Aziz Qasem Jbarah
Keyword(s):  
Complex Formation ◽  
Vibrational Frequencies ◽  
Geometric Optimization ◽  
Binding Energies ◽  
Formation Reaction ◽  
Calculated Binding Energy ◽  
B3lyp Method ◽  
Different Temperatures ◽  
Formation Equilibria ◽  
Optimized Geometries

The formation equilibria of the dimethyltin(IV) complexes with of N,N,N’,N’-tetraethylethylenediamine (Et4en) in solution were investigated. The stoichiometry and stability constants of the complexes formed in solution phase were determined at different temperatures (15 oC – 35 oC) and in solutions of dioxane-water mixtures of different compositions (15% - 62.5%). The accepted model is composed of the 110, 111, 11-1 and 11-2 species. The thermodynamic parameters H and S associated with the protonation of N,N,N`,N`-tetraethylethylendiamine (Et4en) and its complex formation with the dimethyltin(IV) species were determined. The complex formation reaction is exothermic. The equilibrium constant for the displacement of N,N,N’,N’-tetraethylethylenediamine coordinated to dimethyltin(IV) by some selected DNA constituents was calculated. The Keq values clearly indicate the ability of DNA to displace the coordinated Et4en from its dimethyltin(IV) complex. The nucleotides IMP and GMP have the highest values. The DFT/B3LYP method was used for geometric optimization of the ligand and the complex using the Gaussian 09 program. Also the vibrational frequencies of the ligands and complexes were computed for the optimized geometries. The results shows that there is no imaginary frequencies as found in the calculated vibrational frequencies. The binding energies of the dimethyltin(IV) complexes were calculated. All calculated binding energy values are negative.

Comparison of STO-3G and 3-21G ab initio harmonic force fields for ethane, propane, dimethyl ether, and cyclobutane: effects of geometry and scaling on calculated frequencies, eigenvectors, and infrared absorption intensities

1988 ◽  
Vol 66 (5) ◽  
pp. 1318-1332 ◽  
Author(s):  
R. Anthony Shaw ◽  
Charles Ursenbach ◽  
Arvi Rauk ◽  
Hal Wieser
Keyword(s):  
Force Field ◽  
Ab Initio ◽  
Dimethyl Ether ◽  
Infrared Absorption ◽  
Force Fields ◽  
Vibrational Frequencies ◽  
Harmonic Force ◽  
Scaling Factors ◽  
Bond Lengths ◽  
Optimized Geometries

Ab initio harmonic force fields were calculated for ethane, propane, dimethyl ether, and cyclobutane at the STO-3G and 3-21G levels. The calculated frequencies, displacement eigenvectors, and calculated infrared absorption intensities were compared as they derive from force constants that were (i) unsealed; (ii) scaled to fit observed vibrational frequencies reported in the literature; (iii) evaluated at the optimized geometries; and (iv) evaluated at structures for which the bond lengths were corrected from the optimized geometries according to published procedures. A total of nine combinations of ab initio force field/reference geometry/G-matrix geometry were investigated for each of the four molecules. The ability of scaling factors as the only variables to predict vibrational parameters from STO-3G and 3-21G force fields was explored. Conditions were examined for which the scaling factors are satisfactorily transferable among different molecules.

A Theoretical Study of BF + OH and BO + HF Reactions

1995 ◽  
Vol 418 ◽  
Author(s):  
M. R. Soto
Keyword(s):  
Reaction Mechanism ◽  
Ab Initio ◽  
Theoretical Study ◽  
Zero Point ◽  
Vibrational Frequencies ◽  
Multiconfigurational Methods ◽  
Optimized Geometries

AbstractThe reactions of BF + OH and BO + HF are critical reactions in the reaction mechanism of fluorine-enriched boron combustion.1 In this study, ab initio multiconfigurational methods have been used to calculate energies, optimized geometries, harmonic vibrational frequencies and zero-point energies for reactants, products and intermediates of these reactions. Results for the following reactive pathways will be discussed:

Conformational and Vibrational Analysis of 2-, 3- and 4-Pyridinecarbonyl Chloride Using DFT

2016 ◽  
Vol 230 (5-7) ◽  
Author(s):  
Sahar Abdalla ◽  
Yunusa Umar ◽  
Issraa Mokhtar
Keyword(s):  
Vibration Analysis ◽  
Density Functional ◽  
Dipole Moments ◽  
Vibrational Analysis ◽  
Vibrational Frequencies ◽  
Basis Set ◽  
Hybrid Density Functional ◽  
Optimized Geometries

AbstractThe conformation and vibration analysis of 2-, 3- and 4-pyridinecarbonyl chlorides have been computed using B3LYP hybrid density functional with 6-311++G** basis set. All structures have been fully optimized, and the optimized geometries, dipole moments, infrared vibrational frequencies and relative energies are reported. From the computations, 2-pyridinecarbonyl chloride is predicted to exist predominantly in

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