Intramolecular chiral discrimination between meso and d, l isomers

1975 ◽  
Vol 343 (1632) ◽  
pp. 11-16 ◽  
Keyword(s):  
Ab Initio ◽  
Molecular Orbital ◽  
Short Range ◽  
Intramolecular Interaction ◽  
Preceding Paper ◽  
Energy Difference ◽  
Chiral Discrimination ◽  
Molecular Orbital Calculations ◽  
Chiral Molecules ◽  
Intermolecular Contacts

The problem of short-range (contact) interactions between chiral molecules is modelled by that of intramolecular interaction within a molecule formed by combining chiral moieties. The example used is 2,3-dicyanobutane in its active and meso isomers. The energy difference between the two conformational minima, which is the analogue of the intermolecular discrimination energy, is found by ab initio molecular orbital calculations to be 3.1 kJ mol -1 in favour of the meso species. A simpler calculation with the help of a pairwise additivity scheme (see Craig, Radom & Stiles 1975, preceding paper) gives 2.9 k J mol -1 . These discriminations are much greater than any found previously for dispersive and electrostatic forces, but on account of the stronger binding of the chiral moieties are expected to be greater than in intermolecular contacts.

Ab Initio Studies on the Interaction Between Copper(I) and 5-Nitrotetrazolate Anion

2017 ◽  
Vol 68 (1) ◽  
pp. 12
Author(s):  
V. Venkatesan
Keyword(s):  
Binding Energy ◽  
Ab Initio ◽  
Molecular Orbital ◽  
Natural Bond Orbital ◽  
Energy Difference ◽  
Atoms In Molecules ◽  
Basis Sets ◽  
Molecular Orbital Calculations

<p class="p1">Ab initio molecular orbital calculations on the interaction between Copper(I) and 5-nitrotetrazolate anion were done using different basis sets, at the HF, B3LYP and MP2 levels of theory. Three minima were found to 1A, 1B and IC structures of Cu(I)-5-NTz complex. At the B3LYP/LanL2DZ level, the energy difference between 1A and 1B was computed to be 8.18 kcal/mol, while that between 1A and 1C is 22.76 kcal/mol. The presence of both Cu-N and Cu-O interactions is revealed in 1A structure using both natural bond orbital and atoms-in-molecules analyses, which makes more stable than those of 1B and 1C complexes. The binding energy corrected for both ZPE and BSSE for 1A is found to be -150.59 kcal/mol at the B3LYP/LanL2DZ level. The barrier for the 1B <span class="s1">→</span> 1A and 1C <span class="s1">→</span> 1B conversion is calculated to be 7.80 kcal/mol and 9.40 kcal/mol, respectively.</p>

A pairwise additivity scheme for conformational energies of substituted ethanes

1975 ◽  
Vol 343 (1632) ◽  
pp. 1-10 ◽  
Keyword(s):  
Large Deviations ◽  
Ab Initio ◽  
Dihedral Angle ◽  
Molecular Orbital ◽  
Methyl Groups ◽  
Molecular Orbital Calculations ◽  
Linear Combinations ◽  
Strongly Interacting ◽  
Conformational Energies

Ab initio molecular orbital calculations are used to explore additivity in the conformational energies of poly-substituted ethanes in terms of conformational energies of ethane and appropriate mono- and 1,2-di-substituted derivatives. Such relations would allow complex calculations for poly-substituted ethanes to be replaced by much simpler ones on a small number of parent molecules. General expressions for the linear combinations are derived from the assumption that interactions between vicinal substituents are pairwise additive and depend only on the vicinal dihedral angle. The additivity scheme is tested for 15 ethanes, di-, tri- or tetrasubstituted by cyano and methyl groups and for a smaller number of fluoroethanes. Additivity applies to within 0.1- 0.3 k J mol -1 in the methylethanes and mostly to within about 0.7- 0.8 kJ mol -1 in cyanoethanes. Large deviations are found among the geminally substituted fluoroethanes. It is suggested that the additivity approximation is most successful in the absence of strongly interacting geminal groups. Predictions are made of conformational energies of ten hexa(cyano- and methyl-) substituted ethanes.

Gas-Phase Tautomerism in the Triazoles and Tetrazoles: A Study by Photoelectron Spectroscopy and ab Initio Molecular Orbital Calculations

1981 ◽  
Vol 36 (11) ◽  
pp. 1246-1252 ◽  
Author(s):  
Michael H. Palmer ◽  
Isobel Simpson ◽  
J. Ross Wheeler
Keyword(s):  
Ab Initio ◽  
Gas Phase ◽  
Molecular Orbital ◽  
Photoelectron Spectroscopy ◽  
Relative Stability ◽  
Photoelectron Spectra ◽  
Equilibrium Geometry ◽  
Molecular Orbital Calculations ◽  
Methyl Derivatives

The photoelectron spectra of the tautomeric 1,2,3,- and 1,2,4-triazole and 1,2,3,4-tetrazole systems have been compared with the corresponding N-methyl derivatives. The dominant tautomers in the gas phase have been identified as 2 H-1,2,3-triazole, 1 H-1,2,4-triazole and 2H-tetrazole.Full optimisation of the equilibrium geometry by ab initio molecular orbital methods leads to the same conclusions, for relative stability of the tautomers in each of the triazoles, but the calculations wrongly predict the tetrazole tautomerism.

Prediction of Charge Transport Properties of Molecular Materials by Ab Initio Molecular Orbital Calculations

2000 ◽  
Vol 660 ◽  
Author(s):  
Wataru Sotoyama ◽  
Tomoaki Hayano ◽  
Hiroyuki Sato ◽  
Azuma Matsuura ◽  
Toshiaki Narusawa
Keyword(s):  
Charge Transport ◽  
Ab Initio ◽  
Molecular Orbital ◽  
Electron Mobility ◽  
Molecular Orbital Calculations ◽  
Molecular Materials ◽  
Structural Reorganization ◽  
Charge Hopping ◽  
Reorganization Energies ◽  
A Charge

ABSTRACTWe developed a method to predict the charge transport (CT) type (hole or electron) in molecular materials that uses molecular orbital calculations. The hole-and-electron-mobility ratios of molecular materials were calculated based on molecular structural reorganization energies in a charge hopping process. The CT types predicted from the calculated mobility ratios agreed with those experimentally obtained in seven of the eight model molecules.

scholarly journals Effect of BrU on the transition between wobble Gua-Thy and tautomeric Gua-Thy base-pairs: ab initio molecular orbital calculations

2013 ◽  
Vol 433 ◽  
pp. 012035
Author(s):  
Kazuya Nomura ◽  
Ryota Hoshino ◽  
Yasuhiro Hoshiba ◽  
Victor I Danilov ◽  
Noriyuki Kurita
Keyword(s):  
Ab Initio ◽  
Molecular Orbital ◽  
Molecular Orbital Calculations ◽  
Base Pairs
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