Ab initio SCF MO and natural bond orbital studies of 7-silanorbornadiene and 7,7-dimethyl-7-silanorbornadiene. Two molecules possessing an inverted sequence of .pi. orbitals

1990 ◽  
Vol 112 (5) ◽  
pp. 1710-1722 ◽  
Author(s):  
Michael N. Paddon-Row ◽  
Stephen S. Wong ◽  
Kenneth D. Jordan
Keyword(s):  
Ab Initio ◽  
Natural Bond Orbital ◽  
Pi Orbitals

scholarly journals Tipping the balance: theoretical interrogation of divergent extended heterolytic fragmentations

2020 ◽  
Vol 11 (8) ◽  
pp. 2231-2242 ◽  
Author(s):  
Croix J. Laconsay ◽  
Ka Yi Tsui ◽  
Dean J. Tantillo
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Electric Field ◽  
Ab Initio ◽  
External Electric Field ◽  
Density Functional ◽  
Natural Bond Orbital ◽  
Nbo Analysis ◽  
Functional Theory

We interrogate a type of heterolytic fragmentation called a ‘divergent fragmentation’ using density functional theory (DFT), natural bond orbital (NBO) analysis, ab initio molecular dynamics (AIMD), and external electric field (EEF) calculations.

scholarly journals Theoretical insights into the properties of the borazine… X- complexes (X- = H, F, Cl, CN, NC or NCO)

2009 ◽  
Vol 74 (10) ◽  
pp. 1105-1111 ◽  
Author(s):  
Reza Ghiasi
Keyword(s):  
Charge Transfer ◽  
Chemical Shift ◽  
Total Energy ◽  
Ab Initio ◽  
Intermolecular Interactions ◽  
Natural Bond Orbital ◽  
Nbo Analysis ◽  
Interaction Energies ◽  
Ab Initio Method ◽  
Nucleus Independent Chemical Shift

The character of the NH ...X- (X- = H, F, Cl, CN, NC or NCO) interactions of borazine with anions was studied using ab initio method. The interaction energies were calculated at the B3LYP/6-311++G(d,p) level. The energetic and geometric characteristics of the complexes were compared. The 'atoms in molecules' methodology was used to analyze the electron density and to obtain atomic contributions to the total energy and charge of the systems. Natural bond orbital (NBO) analysis demonstrated the charge transfer in the study of the nature of the intermolecular interactions. The aromaticity of these compounds was predicted in light of the nucleus-independent chemical shift (NICS).

Stereoelectronic interaction effects on the conformational properties of 5-methyl-5-aza-1,3-dithiacyclohexane and its analogous containing N, P, O, and Se atoms — A hybrid density functional theory (DFT), ab initio study, and natural bond orbital (NBO) analysis

2010 ◽  
Vol 88 (7) ◽  
pp. 579-587 ◽  
Author(s):  
Davood Nori-Shargh ◽  
Neda Hassanzadeh ◽  
Meisam Kosari ◽  
Parvin Rabieikarahroudi ◽  
Hooriye Yahyaei ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Natural Bond Orbital ◽  
Nbo Analysis ◽  
Hybrid Density Functional Theory ◽  
Functional Theory ◽  
Dipole Interactions ◽  
Conformational Properties ◽  
Hybrid Density Functional

Natural bond orbital (NBO) analysis, hybrid density functional theory (hybrid DFT: B3LYP/6-311+G**//B3LYP/6-311+G**), and ab initio molecular orbital (MO: MP2/6-311+G**//B3LYP/6-311+G**) based methods were used to study the electronic delocalization energy (DE), dipole–dipole interactions, and steric repulsions on the conformational properties of 5-methyl-5-aza-1,3-dioxacyclohexane (1) (-phospha- (2), -arsena- (3)), 5-methyl-5-aza-1,3-dithiacyclohexane (4) (-phospha- (5), -arsena- (6)), and 5-methyl-5-aza-1,3-diselenacyclohexane (7) (-phospha- (8), -arsena- (9)). The MP2/6-311+G**//B3LYP/6-311+G** and B3LYP/6-311+G**//B3LYP/6-311+G** results revealed that the axial stereoisomers of compounds 1–9 are more stable than their equatorial stereoisomers. In this regard, the obtained results showed an egregious axial preference for compounds 1, 4, and 7. Importantly, the results showed that the energy differences between the axial and equatorial stereoisomers decrease from compounds 1 → 3, 4 → 6, and also, 7 → 9. The NBO analysis of donor–acceptor interactions revealed that the calculated DE for compounds 1–3 are –21.50, –7.84, and –4.38 kcal mol–1, respectively. The decrease of the calculated DE values from compound 1 to compound 3 could reasonably explain the decrease of the energy differences between the axial and equatorial stereoisomers from compound 1 to compound 3. The correlation between the DE, dipole–dipole interactions, structural parameters, and conformational behaviors of compounds 1–9 has been investigated.

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>

THEORETICAL INVESTIGATION ON THE STRUCTURE AND PROPERTIES OF ALUMAZINE⋯M COMPLEXES (M = Li+, Na+, K+, Be2+, Mg2+, AND Ca2+)

2013 ◽  
Vol 12 (05) ◽  
pp. 1350033
Author(s):  
MAHTAB FATHI RASEKH
Keyword(s):  
Charge Transfer ◽  
Chemical Shift ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Interaction Energy ◽  
Natural Bond Orbital ◽  
Energy Charge ◽  
Interaction Energies ◽  
Structure And Properties ◽  
Nucleus Independent Chemical Shift

The nature of alumazine⋯M ( M = Li+ , Na+ , K+ , Be2+ , Mg2+ , AND Ca2+ ) interactions was studied by ab initio calculations. The interaction energies were calculated at MP2/6-311++G(d,p)//B3LYP/6-311++G(d,p) level. The calculations suggest that the size and charge of cation are two important factors that affect the interaction energy, charge transfer values and the variation in aromaticity of alumazine ring upon complexation. The theory of atoms in molecules (AIM) and natural bond orbital (NBO) analyses of complexes indicate that the variation of densities and the extent of charge shifts upon complexation correlate well with the obtained interaction energies. Finally, nucleus independent chemical shift (NICS) method was applied for evaluating the variation in aromaticity of alumazine ring upon complexation.

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