scholarly journals Molecular orbital analysis of the hydrogen bonded water dimer

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Bo Wang ◽  
Wanrun Jiang ◽  
Xin Dai ◽  
Yang Gao ◽  
Zhigang Wang ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Functional Materials ◽  
Water Dimer ◽  
Energy Decomposition Analysis ◽  
Functional Theory ◽  
Hartree Fock ◽  
Molecular Orbital Analysis ◽  
Negligible Contribution

Abstract As an essential interaction in nature, hydrogen bonding plays a crucial role in many material formations and biological processes, requiring deeper understanding. Here, using density functional theory and post-Hartree-Fock methods, we reveal two hydrogen bonding molecular orbitals crossing the hydrogen-bond’s O and H atoms in the water dimer. Energy decomposition analysis also shows a non-negligible contribution of the induction term. Our finding sheds light on the essential understanding of hydrogen bonding in ice, liquid water, functional materials and biological systems.

On the Nature of Halide-Water Interactions: Insights from Many-Body Representations and Density Functional Theory

2019 ◽  
Author(s):  
Brandon B. Bizzarro ◽  
Colin K. Egan ◽  
Francesco Paesani
Keyword(s):  
Density Functional Theory ◽  
Charge Transfer ◽  
Molecular Orbital ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Orbital Energy ◽  
Energy Decomposition Analysis ◽  
Interaction Energies ◽  
Many Body ◽  
Functional Theory

<div> <div> <div> <p>Interaction energies of halide-water dimers, X<sup>-</sup>(H<sub>2</sub>O), and trimers, X<sup>-</sup>(H<sub>2</sub>O)<sub>2</sub>, with X = F, Cl, Br, and I, are investigated using various many-body models and exchange-correlation functionals selected across the hierarchy of density functional theory (DFT) approximations. Analysis of the results obtained with the many-body models demonstrates the need to capture important short-range interactions in the regime of large inter-molecular orbital overlap, such as charge transfer and charge penetration. Failure to reproduce these effects can lead to large deviations relative to reference data calculated at the coupled cluster level of theory. Decompositions of interaction energies carried out with the absolutely localized molecular orbital energy decomposition analysis (ALMO-EDA) method demonstrate that permanent and inductive electrostatic energies are accurately reproduced by all classes of XC functionals (from generalized gradient corrected (GGA) to hybrid and range-separated functionals), while significant variance is found for charge transfer energies predicted by different XC functionals. Since GGA and hybrid XC functionals predict the most and least attractive charge transfer energies, respectively, the large variance is likely due to the delocalization error. In this scenario, the hybrid XC functionals are then expected to provide the most accurate charge transfer energies. The sum of Pauli repulsion and dispersion energies are the most varied among the XC functionals, but it is found that a correspondence between the interaction energy and the ALMO EDA total frozen energy may be used to determine accurate estimates for these contributions. </p> </div> </div> </div>

scholarly journals Direct estimate of the internal π-donation to the carbene centre within N-heterocyclic carbenes and related molecules

2015 ◽  
Vol 11 ◽  
pp. 2727-2736 ◽  
Author(s):  
Diego M Andrada ◽  
Nicole Holzmann ◽  
Thomas Hamadi ◽  
Gernot Frenking
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Heterocyclic Carbenes ◽  
Energy Decomposition Analysis ◽  
Energy Decomposition ◽  
Direct Estimate ◽  
Functional Theory ◽  
Bonding Analysis

Fifteen cyclic and acylic carbenes have been calculated with density functional theory at the BP86/def2-TZVPP level. The strength of the internal X→p(π) π-donation of heteroatoms and carbon which are bonded to the C(II) atom is estimated with the help of NBO calculations and with an energy decomposition analysis. The investigated molecules include N-heterocyclic carbenes (NHCs), the cyclic alkyl(amino)carbene (cAAC), mesoionic carbenes and ylide-stabilized carbenes. The bonding analysis suggests that the carbene centre in cAAC and in diamidocarbene have the weakest X→p(π) π-donation while mesoionic carbenes possess the strongest π-donation.

scholarly journals Correction: New light on an old debate: does the RCN–PtCl2 bond include any back-donation? RCN ← PtCl2 backbonding vs. the IR νCN blue-shift dichotomy in organonitriles–platinum(ii) complexes. A thorough density functional theory – energy decomposition analysis study

2019 ◽  
Vol 48 (35) ◽  
pp. 13491-13492 ◽  
Author(s):  
Girolamo Casella ◽  
Célia Fonseca Guerra ◽  
Silvia Carlotto ◽  
Paolo Sgarbossa ◽  
Roberta Bertani ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Blue Shift ◽  
Energy Decomposition Analysis ◽  
Energy Decomposition ◽  
Functional Theory ◽  
Dalton Trans ◽  
Analysis Study ◽  
Back Donation

Correction for ‘New light on an old debate: does the RCN–PtCl2 bond include any back-donation? RCN ← PtCl2 backbonding vs. the IR νCN blue-shift dichotomy in organonitriles–platinum(ii) complexes. A thorough density functional theory – energy decomposition analysis study’ by Girolamo Casella et al., Dalton Trans., 2019, DOI: 10.1039/c9dt02440a.

scholarly journals Cobalt-catalyzed C–H cyanations: Insights into the reaction mechanism and the role of London dispersion

2018 ◽  
Vol 14 ◽  
pp. 1537-1545 ◽  
Author(s):  
Eric Detmar ◽  
Valentin Müller ◽  
Daniel Zell ◽  
Lutz Ackermann ◽  
Martin Breugst
Keyword(s):  
Reaction Mechanism ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Energy Decomposition Analysis ◽  
Local Energy ◽  
Energy Decomposition ◽  
Functional Theory ◽  
London Dispersion ◽  
Cobalt Center

Carboxylate-assisted cobalt(III)-catalyzed C–H cyanations are highly efficient processes for the synthesis of (hetero)aromatic nitriles. We have now analyzed the cyanation of differently substituted 2-phenylpyridines in detail computationally by density functional theory and also experimentally. Based on our investigations, we propose a plausible reaction mechanism for this transformation that is in line with the experimental observations. Additional calculations, including NCIPLOT, dispersion interaction densities, and local energy decomposition analysis, for the model cyanation of 2-phenylpyridine furthermore highlight that London dispersion is an important factor that enables this challenging C–H transformation. Nonbonding interactions between the Cp* ligand and aromatic and C–H-rich fragments of other ligands at the cobalt center significantly contribute to a stabilization of cobalt intermediates and transition states.

scholarly journals Complementary Base Lowers the Barrier in SuFEx Click Chemistry for Primary Amine Nucleophiles

2020 ◽  
Author(s):  
Jan-Niclas Luy ◽  
Ralf Tonner
Keyword(s):  
Primary Amine ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Building Blocks ◽  
Energy Decomposition Analysis ◽  
Electronic Effects ◽  
Functional Theory ◽  
Molecular Building Blocks ◽  
Further Development ◽  
Crucial Ingredient

The Sulfur (VI) Fluoride Exchange (SuFEx) reaction is an emerging scheme for connecting molecular building blocks. Due to its broad functional group tolerance and rather stable resulting linkage it is seeing rapid adoption in various fields of chemistry. Still, to date the reaction mechanism is poorly understood which hampers further development. Here, we show that the mechanism of the SuFEx reaction for the prototypical example of methanesulfonyl fluoride reacting with methylamine can be understood as an SN2-type reaction. By analyzing the reaction path with the help of density functional theory in vacuo and under consideration of solvent and co-reactant influence we identify the often used complementary base as crucial ingredient to lower the reaction barrier significantly by increasing the nucleophilicity of the primary amine. With the help of energy decomposition analysis (EDA) at the transition state structures we quantify the underlying stereo-electronic effects and propose new avenues for experimental exploration of the potential of SuFEx chemistry.

Switching On/Off the Intramolecular Hydrogen Bonding of 2-Methoxyphenol Conformers: An NMR Study

2020 ◽  
Vol 73 (3) ◽  
pp. 222
Author(s):  
Frederick Backler ◽  
Feng Wang
Keyword(s):  
Hydrogen Bonding ◽  
Chemical Shift ◽  
1H Nmr ◽  
Density Functional ◽  
Point Group ◽  
Decomposition Analysis ◽  
Intramolecular Hydrogen Bonding ◽  
Group Symmetry ◽  
Energy Decomposition Analysis ◽  
Intramolecular Hydrogen

Intramolecular hydrogen bonding of 2-methoxyphenol (2-MP, guaiacol) is studied using NMR spectroscopy combined with quantum mechanical density functional theory (DFT) calculations. The hydrogen bonding of OH⋯O and HO⋯H is switched on in the conformers of anti–syn (AS, 99.64% dominance) and anti–gauche (AG), respectively, with respect to the anti–anti (AA) conformer (without either such hydrogen bonding interactions). It confirms that the 13C and 1H NMR chemical shift of AS dominates the measured NMR spectra, as the AS conformer reproduces the measurements in CDCl3 solvent (RMSD of 1.86ppm for 13C NMR and of 0.27ppm for 1H NMR). The chemical shift of hydroxyl H(1) at 5.66 pm is identified as the fingerprint of the OH(1)⋯OCH3 hydrogen bonding in AS, as it exhibits a significant deshielding from H(1) of AA (4.24ppm) and H(1) of AG (4.38ppm) without such OH(1)⋯OCH3 hydrogen bonding. The AG conformer (C1 point group symmetry) possesses a less strong hydrogen bonding of HO⋯HCH2O, with the methoxyl group out of the aromatic phenol plane. The substituent effect of AG due to the resonance interaction of methoxyl being out of plane in a concentrated solution shifts the ortho- and para-aromatic carbons, C(3)/C(5), of the AG to ~125.05/125.44ppm from the corresponding carbons in AS at 108.81/121.60ppm. The hydrogen bonding exhibits inwards reduction of IR frequency regions of AS and AG from AA. Finally, energy decomposition analysis (EDA) indicates that there is a steric energy of 45.01kcal mol−1 between the AS and AG when different intramolecular hydrogen bonding is switched on.

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