Molecular Orbital Energy Decomposition Analysis Research Articles

A theoretical study of the strong interactions between carbon dioxide and OH+ and NH2 + products resulting from protonation of 1,2-dioxirane-3-one and 1,2-oxaziridine-3-one, respectively

In this work, we investigate the nature of the O–O and O–N interactions in protonated 1,2-dioxirane-3-one derivatives and protonated 1,2-oxaziridine-3-one derivatives, respectively. The quantum theory of atoms in molecules and the natural bond orbital (NBO) method in conjunction with the localized molecular orbital energy decomposition analysis (LMOEDA) have been used. LMOEDA and NBO analyses reveal that the O–O and O–N interactions exhibit characteristics of dative covalent bonds. In addition, the L(r) = −∇2 ρ(r) function reveals that the O–O and O–N interactions can be categorized as strong hole–lump interactions.

Evaluating the Free Energies of Solvation and Electronic Structures of Lithium-Ion Battery Electrolytes.

Adaptive biasing force molecular dynamics simulations and density functional theory calculations were performed to understand the interaction of Li(+) with pure carbonates and ethylene carbonate (EC)-based binary mixtures. The most favorable Li carbonate cluster configurations obtained from molecular dynamics simulations were subjected to detailed structural and thermochemistry calculations on the basis of the M06-2X/6-311++G(d,p) level of theory. We report the ranking of these electrolytes on the basis of the free energies of Li-ion solvation in carbonates and EC-based mixtures. A strong local tetrahedral order involving four carbonates around the Li(+) was seen in the first solvation shell. Thermochemistry calculations revealed that the enthalpy of solvation and the Gibbs free energy of solvation of the Li(+) ion with carbonates are negative and suggested the ion-carbonate complexation process to be exothermic and spontaneous. Natural bond orbital analysis indicated that Li(+) interacts with the lone pairs of electrons on the carbonyl oxygen atom in the primary solvation sphere. These interactions lead to an increase in the carbonyl (C=O) bond lengths, as evidenced by a redshift in the vibrational frequencies [ν(C=O)] and a decrease in the electron density values at the C=O bond critical points in the primary solvation sphere. Quantum theory of atoms in molecules, localized molecular orbital energy decomposition analysis (LMO-EDA), and noncovalent interaction plots revealed the electrostatic nature of the Li(+) ion interactions with the carbonyl oxygen atoms in these complexes. On the basis of LMO-EDA, the strongest attractive interaction in these complexes was found to be the electrostatic interaction followed by polarization, dispersion, and exchange interactions. Overall, our calculations predicted EC and a binary mixture of EC/dimethyl carbonate to be appropriate electrolytes for Li-ion batteries, which complies with experiments and other theoretical results.

Structure, binding energy and chiral discrimination in oxathiirane homodimers

Oxathiirane (XHCSO) homodimers bonded by hydrogen bonds (HB) and chalcogen bonds (YB) were studied at the Møller-Plesset (MP2) computational level. Binding energies obtained at the Coupled-Cluster level up to the Complete Basis Set limit [CCSD(T)/CBS] indicate that HB complexes present stronger binding modes than the YB complexes. In terms of chiral discrimination energy, R,S complexes are favored over R,R complexes with the exceptions of SiCl3 and SiF3 derivatives. Natural Bond Orbital (NBO) results are in agreement with the interaction energies in the case of the HB complexes, but could not discriminate between R,R and R,S in the YB complexes. The lack of correlation between molecular electrostatic values on the 0.001a.u. and binding energies, in addition to the discrepancies between Atoms in Molecules (AIM) and NBO results may suggest that the electrostatics is not the dominant term in the interaction energy. This was corroborated by the Localized Molecular Orbital Energy Decomposition Analysis (LMOEDA) calculations which showed that the exchange and dispersion terms are the most important attractive components for all the complexes studied, contributing up to 50.6% and 42.5% to the total attractive forces respectively.

Theoretical investigation of the interactions between the π‐systems of molecular organic semiconductors and an analysis of the contributions of repulsion and electrostatics

A concept for the interactions between π‐systems is necessary to understand a number of phenomena in modern material sciences such as supramolecular properties and self‐assembly. In the present article, we investigate the intermolecular interaction energies between organic semiconductors with extended π‐systems using SAPT (symmetry‐adapted perturbation theory), LMO‐EDA (localized molecular orbital energy decomposition analysis), DFT‐D (density functional theory including dispersion corrections), and force‐field approaches. Both apolar organic molecules such as acenes and highly polarized π‐systems of merocyanines and squaraines were used to probe the influence of electrostatics on the shape of the potential energy surfaces (PES) governing the geometric structures of aggregates. Our results reveal that the shapes of the PESs result from variations in the short‐range, highly specific repulsion forces even for highly polar molecules. Using distributed quadrupoles, we show that it is nevertheless possible to mimic the intermolecular potentials with electrostatics. This is also possible with van‐der‐Waals potentials and a simple overlap‐based force‐field ansatz based on the overlap between p‐orbitals. © 2016 Wiley Periodicals, Inc.

Theoretical investigation of the hydrogen bond interactions of methanol and dimethylamine with hydrazone and its derivatives

The interactions between hydrogen bond donors (dimethylamine (DMA) and methanol (MeOH)) and acceptors (formaldehyde dimethylhydrazone, acetaldehyde N,N-dimethylhydrazone and N-nitrosodimethylamine) were theoretically investigated by DFT. The hydrogen bonding interactions were found on several bonding sites of the acceptors. The important properties of structure, binding energy, enthalpy of formation, Gibbs free energy of formation and equilibrium constant were investigated. Compared to the monomer, the DMA complexes show a small red shift of the NH-stretching vibrational transition but a significantly intensity enhancement. On the other hand, the MeOH complexes have a large red shift but a relatively small intensity enhancement of the OH-stretching transition. Atoms-in-molecules analysis revealed that several types of hydrogen bond interaction were present in the complexes. Since natural bond orbital analysis overestimated the effect of charge transfer, the more reliable localized molecular orbital energy decomposition analysis was performed and it shows that the major contribution to the total interaction energy is the electrostatic interaction. All these parameters suggest that the hydrogen bond donor strength of MeOH is substantially greater than DMA.

Structural diversity of manganese(II) complexes containing 2,2′-dipyridylamine and benzenedicarboxylates. Conformational analysis of tere-, iso- and phthalate ions: An experimental and quantum chemical approach

Four novel manganese(II) complexes with 2,2′-dipyridylamine (dipya) and various benzenedicarboxylate, BDC, ligands as anions of phthalic (pht), isophthalic (ipht) and terephthalic (tpht) acids were hydrothermally synthesized, namely, [Mn(dipya)(pht)(H2O)]2 (1), [Mn(dipya)(ipht)]n (2), [Mn(dipya)2(tpht)]n (3), and [Mn(dipya)(H2O)4](tpht) (4). All complexes were characterized by single-crystal X-ray diffraction, TG/DSC analysis and IR spectroscopy. The obtained complexes display a plenty of different structural features, including geometry of central metal atoms, BDC coordination modes and crystal packing. The coordination numbers of Mn(II) are different: 5 (in 2), 6 (in 3 and 4) and 7 (in 1). 3D networks in 1–4 are determined by strong non-covalent interactions. A survey of the Cambridge Structural Database for BDC complexes was performed in order to analyze orientation of COO groups. The energies of various BDC conformers were calculated by the second order Møller–Plesset perturbation theory and three hybrid HF/DFT methods with 6-311G∗∗ basis set. To explain different behavior, BDC ions were also examined by Localized Molecular Orbital Energy Decomposition and Natural Bond Orbital analyses. Experimental and calculated geometries are in agreement, showing that tpht and ipht anions prefer the planar conformation, while in pht anions COO groups are inclined and make complementary angles relative to the aromatic rings.

The C[sbnd]O rotation in the gaseous glycine. An energy decomposition analysis study

The physical origins of the CO rotations in glycine are explored theoretically. By the localized molecular orbital energy decomposition analysis (LMO-EDA) method, the rotation barriers are decomposed into the electrostatic, exchange–repulsion, polarization, correlation and geometrical relaxation terms. In general, the CO rotations are controlled by Pauli repulsion and polarization interactions. However, if the rotated conformer has obvious inter-group interaction between COOH and NH2, the physical origin of the CO rotation is changed, which is governed by polarization and correlation interactions.

Buckybowls as adsorbents for CO2, CH4, and C2H2: Binding and structural insights from computational study.

Noncovalent functionalization of buckybowls sumanene (S), corannulene (R), and coronene (C) with greenhouse gases (GGs) such as CO2 , CH4 (M), and C2 H2 (A) has been studied using hybrid density functional theory. The propensity and preferences of these small molecules to interact with the concave and convex surfaces of the buckybowls has been quantitatively estimated. The results indicate that curvature plays a significant role in the adsorption of these small molecules on the π surface and it is observed that buckybowls have higher binding energies (BEs) compared with their planar counterpart coronene. The concave surface of the buckybowl is found to be more feasible for adsorption of small molecules. BEs of small molecules towards π systems is CO2 > A > M and the BEs of π systems toward small molecules is S > R > C. Obviously, the binding preference is dictated by the way in which various noncovalent interactions, such as π···π, lone pair···π, and CH···π manifest themselves on carbaneous surfaces. To delineate the intricate details of the interactions, we have employed Bader's quantum theory of atoms in molecule and localized molecular orbital energy decomposition analysis (LMO-EDA). LMO-EDA, which measures the contribution of various components and traces the physical origin of the interactions, indicates that the complexes are stabilized largely by dispersion interactions.

Computational Design of Functionalized Imidazolate Linkers of Zeolitic Imidazolate Frameworks for Enhanced CO2 Adsorption

Zeolitic imidazolate frameworks (ZIFs) represent the class of metal–organic frameworks (MOFs) that possess high porosity, large surface area, exceptional thermal, and chemical stability. Because of these properties, ZIFs are being employed extensively in gas separation and selective CO2 adsorption. We have chosen the structural modification approach to enhance the CO2 binding ability of various imidazolate (Im) linkers of ZIFs by systematically varying the substituents at 2, 4, and 5 positions of Im ring with CH3, Cl, CN, OH, NH2, and NO2 functional groups. Density functional theory (DFT) calculations have been employed to identify and quantify the CO2 binding ability of various adsorption sites present in 137 Im linkers. The study demonstrates that the Im linkers with asymmetrical substitution, viz. NO2/OH, CN/OH, and Cl/OH combinations are highly promising linkers of ZIFs for efficient CO2 adsorption. The QTAIM analysis characterizes these interactions as noncovalent interactions which are stabilized by weak hydrogen bond and van der Waals (vdWs) interactions. Localized molecular orbital energy decomposition analysis (LMO-EDA) performed on substituted Im···CO2 complexes reveals that CO2 binding is governed by a combination of H-bonding, electrostatic, and dispersion interactions. The findings of the study will serve as guide-in principles to synthesize new adsorbents with enhanced and selective CO2 adsorption.

Complexes of nitric oxide with water and imidazole

NO–Imi–H2O complexes can be used as models to investigate the interactions of histidine with nitric oxide and water in biological systems like myoglobin. We discuss here the water–imidazole, water–nitric oxide dimers and the trimolecular complexes of nitric oxide with water and imidazole from the donor–acceptor point of view using the natural bond orbitals and localized molecular orbital energy decomposition analysis schemes. The comparison between trimolecular and bimolecular complexes shows that in general, the stabilization energies are more sensitive to changes in the interactions of imidazole with water than to changes in the interactions with nitric oxide. The effect of imidazole ring protonation on the geometry and stabilization of the complexes is also investigated. We found that cooperative effects are more relevant in charged complexes and planar structures than in neutral species and nonplanar complexes. The driving forces governing the interactions between open and closed shell systems are also discussed with special emphasis on the role of lone pairs and unpaired electrons.

Tuning anion-π interaction via halogen substituent effects in cyanuric acids and its derivatives

Several anion-π complexes of isocyanuric acid, thioderivatives and their halogen substituted derivatives with chloride anion have been studied. The geometric and energetic features, charges transfer from chloride anion to the aromatic rings and “atoms-in-molecules” analysis are performed and discussed for these complexes. The results show that the strength of the anion-π interaction between cyanuric derivatives and chloride anion can be tuned by halogen-substituting. The localized molecular orbital energy decomposition analyses shows that, in the total interaction, exchange and electrostatic energies are the dominant stabilizing forces, and the polarization energies also make a favorable contribution. Finally, solvent effect significantly weakens the anion-π interaction between the isocyanuric derivatives and chloride anion, especially in polar solvents. © 2015 Wiley Periodicals, Inc.

A comparative study of the chalcogen bond, halogen bond and hydrogen bond S⋯O/Cl/H formed between SHX and HOCl.

Ab initio quantum chemistry methods were used to analyze the noncovalent interactions between HOCl and SHX (X = F, CN, NC, Cl, Br, NO2, CCH, CH3, H). Three energetic minimal configurations were characterized for each case, where the S center acts as a Lewis acid interacting with O to form a chalcogen bond, as well as a Lewis base interacting with Cl or H of HOCl to form halogen bond and hydrogen bond, respectively. An electronegative substituent such as F, CN, NC and NO2 tends to form a stronger chalcogen bond, while an electropositive substituent such as CCH, CH3 and H is inclined to form a more stable H-bonded complex. The chalcogen-bonded, halogen-bonded and H-bonded complexes are stabilized by charge transfers from Lp(O) to σ*(SX), from Lp(S) to σ*(ClO), and from Lp(S) to σ*(HO), respectively. As a result, the SHX unit becomes positively charged in halogen-bonded and hydrogen-bonded complexes but negatively charged in chalcogen-bonded complexes. Theory of atoms in molecules, natural bond orbital analysis, molecular electrostatic potential and localized molecular orbital energy decomposition analysis were applied to investigate these noncovalent bonds.

Insights into ethanol decomposition over Pt: A DFT energy decomposition analysis for the reaction mechanism leading to C2H6 and CH4

The search for environmentally correct processes is one of the greatest challenges in current energy research. Hydrogen production trough ethanol reforming emerges as a promising technology. In this work, the mechanism for ethanol decomposition over platinum was investigated by density functional theory (DFT). The various reaction intermediaries and transition states were optimized over a cluster of five Pt atoms at the B3LYP-D3/6-31+G(d,p) level of theory for ethanol with the SBKJC ECP basis set for the metal atoms. This approach showed to be fully consistent with experimental observations. Two routes were considered, one leading to the formation of CH4 and CO and the other leading to C2H6. In agreement with previous calculation and experimental studies, the route forming CH4 and CO is favored. The reaction barriers were investigated by the Localized Molecular Orbital Energy Decomposition Analysis (LMOEDA) method. In general, the reaction steps that involve solely the scission of a OH or CH bond present elevate reaction barriers. Some other steps, however, include a concomitant strengthening of the CO bond as the CH bond elongates. These reaction steps present relatively low reaction barriers. For some other cases, it is the distinct interaction with the metal experienced by the transition state and the ground state that determines the energy barrier. The LMOEDA method proved to be an invaluable tool for the understanding of reaction mechanisms and for the rational design of news catalysts.

DFT investigation on hydrogen bonding in cyclohexane-1,2,3,4,5-pentol crystal structure

The cyclohexane-1,2,3,4,5-pentol,C6H12O5 is a natural product extracted from Adiscanthus fusciflorus (Rutaceae). It crystallizes in the non-centrosymmetric space group P21 with one molecule in the asymmetric unit and it has been postulated to have at least ten strong O-H…O intermolecular interactions, two per each OH group of one molecule, producing a three-dimensional network. The crystal packing is defined by O-H…O hydrogen bonds. Due to the crucial role of the hydrogen bonds in defining the crystal structure, theoretical investigations in the gas phase have been carried out in order to explore the hydrogenbonding mechanism through a quantitative Kohn-Sham molecular orbital and corresponding energy decomposition analyses. The existence of a covalent component in hydrogen bonds has been proved which originates from donor-acceptor orbital interactions in the σ-electron system. Our analyses show that the stability of the crystal structure is enhanced by the formation of two hydrogen bonds with two vicinal molecules for each OH group in C6H12O5 molecule with respect to the formation of one or two hydrogen bonds with only one vicinal molecule, thus confirming the proposed existence of ten strong O-H…O intermolecular interactions for each molecule in the asymmetric unit. The presence of a cooperativity effect is observed which originates from a charge separation induced by the two vicinal molecules hydrogenbonded to an OH group in C6H12O5 molecule.

The nature of hydrogen bonding in R22(8) crystal motifs – a computational exploration

R22(8), a commonly occurring motif in organic crystals, has been examined here through ab initio and density functional theory (DFT) methods. The 11 R22(8) motifs reported by Allen et al. have been classified into five types; their structural features, hydrogen-bonding patterns and the kind of interactions stabilising these motifs have been studied. Results reveal that the electronegativity of donor atoms plays a major role in directing the hydrogen bonds, whereas their positions in the motif have been found to be less important. Quantum theory of atoms in molecules (QTAIM) and reduced density gradient-based non-covalent-interaction analyses have been used to understand the weak interactions between monomers. Homonuclear interactions within the motifs have been found to be stronger with higher covalent character at the bond critical points than heteronuclear interactions. In addition, a localised molecular orbital energy decomposition analysis (LMOEDA) has been accomplished to provide useful insight into various long- and short-range interactions that contribute to the total stabilisation energies. The stabilising n → σ* interactions have been explained using natural bond orbital (NBO) analysis. Overall, this study provides the essential criteria for an organic crystal to be in an R22(8) motif and further discusses the different combinations of hydrogen-bonding features within the R22(8) motifs.

A computational study of pnicogen−hydride interaction in complexes XH2P⋯HBeY

The pnicogen−hydride interaction in the complexes XH2P⋯HBeY (X=F, Cl and Br; Y=H, F, Cl, Br, and CH3) has been studied and characterized using ab initio quantum chemistry methods. P in XH2P and H in HBeY act as Lewis acid and base respectively. Calculation indicates that the interaction between XH2P and HBeY is strong, comparable with typical hydrogen bonds; the calculated binding energies with BSSE correction by MP4(SDQ)/aug-cc-PVTZ vary from the least 13.29kJ/mol of BrH2P⋅⋅⋅HBeF to the largest 45.63kJ/mol of FH2P⋅⋅⋅ HBeH. The binding energy increases with the acidity of P and the basicity of HBeY. An electron-withdrawing substituent X will enhance but an electron-withdrawing substituent Y will weaken the pnicogen−hydride interaction. Theory of atoms in molecules, natural bond orbitals and natural resonance theory, molecular electrostatic potential and localized molecular orbital energy decomposition analysis were applied to investigate the pnicogen–hydride bonds. A double-way charge transfers and intermolecular hyperconjugations from Lp(P) to σ∗(HBe) and from σ(HBe) to σ∗(XP) mainly contribute to the stability and bonding of the complexes.

Binding energies and interaction origins between nonclassical single-electron hydrogen, sodium and lithium bonds and neutral boron-containing radicals: a theoretical investigation

Nonclassical single electron hydrogen, sodium and lithium bonds (SEHBs, SENaBs and SELiBs) between single electron acceptors X–A (A=H, Na, Li; X=CN, HCC, HO, NC, CF3) and neutral radicals BY2 (Y=H, OH, CH3) and have been systematically investigated by high level theoretical methods, such as second-order Moller-Plesset perturbation theory (MP2), spin-component-scaled Moller-Plesset theory (SCS-MP2), the coupled cluster method with perturbative triples (CCSD(T)), and the correlation consistent composite approach (ccCA). Binding energies have been corrected for zero-point vibrational effects and (when applicable) basis set superposition error. The quantum theory of atoms in molecules (AIM) and natural bond orbital (NBO) analyses were also employed to qualitatively characterize the single electron bond interactions. The stabilization energy was partitioned via the localized molecular orbital energy decomposition analysis (LMO-EDA) method, and both electrostatic and exchange interactions were seen to be major driving forces for the complex stabilization. Interestingly, the sum of the energy contributors of exchange (EEX), repulsion (EREP), polarization (EPOL), dispersion (EDIS) is close to zero and the changes in the interaction energy follow the trend of the electrostatic energy (EES). We observe several linear relationships among the optimized intermolecular parameters and the interaction energies of the various complexes.

Energy Decomposition Scheme Based on the Generalized Kohn–Sham Scheme

In this paper, a new energy decomposition analysis scheme based on the generalized Kohn-Sham (GKS) and the localized molecular orbital energy decomposition analysis (LMO-EDA) scheme, named GKS-EDA, is proposed. The GKS-EDA scheme has a wide range of DFT functional adaptability compared to LMO-EDA. In the GKS-EDA scheme, the exchange, repulsion, and polarization terms are determined by DFT orbitals; the correlation term is defined as the difference of the GKS correlation energy from monomers to supermolecule. Using the new definition, the GKS-EDA scheme avoids the error of LMO-EDA which comes from the separated treatment of EX and EC functionals. The scheme can perform analysis both in the gas and in the condensed phases with most of the popular DFT functionals, including LDA, GGA, meta-GGA, hybrid GGA/meta-GGA, double hybrid, range-separated (long-range correction), and dispersion correction. By the GKS-EDA scheme, the DFT functionals assessment for hydrogen bonding, vdW interaction, symmetric radical cation, charge-transfer, and metal-ligand interaction is performed.

Exploiting Weak Noncovalent Cation···π Interaction for Designing a Molecular Container for Storage of Methane Molecules with Lithiated Carbene Superbases

This study reports the multiprotonation sites exploiting noncovalent interactions to achieve hyperbasicity of an uncharged organic base. A new class of carbene based organic superbase has been designed to attain the proton affinity (PA) value of 301.9 kcal/mol at M06-2X/6-311+G**//B3LYP/6-31+G* level of theory. These designed scaffold molecules can possess three independent protonation sites, which is not available in the literature to date. The stabilization of the protonated forms of the superbases by noncovalent interactions such as C–H+···π interaction is responsible for augmenting the basicity of such carbene systems. The DFT calculated results show that such carbene systems can be suitable candidate for tris-protonation with pKa(MeCN) value of 43.3 and proton affinity value (MeCN) of 312.1 kcal/mol. Molecular electrostatic potential (MESP) analysis shows the existence of electron density at the reactive sites and the role of substituents to enhance the electron density in such designed systems. There is a good correlation with the absolute minima of the MESP (Vmin) located for such carbene systems with their calculated proton affinity values. The frontier molecular orbital energy of such carbenes also shows a good relationship with their proton affinity results. These carbene systems can be utilized further for selective binding of lithium ions over sodium ions. Such lithiated organic superbases can be used as a molecular container for the storage of hydrogen and methane molecules. The energy decomposition analysis (EDA) has been performed to explain the role of various factors which contribute to the total binding strength of the hydrogen or methane molecules with lithiated carbene superbases. The localized molecular orbital energy decomposition analysis reveals that the electrostatic and polarization effects are the major contributing factors in interactions with methane and hydrogen molecules. This is the first report where the organic superbase has been exploited as efficient methane storage materials.

A Quantum Chemical Study on Hydration of Ra (II): Comparison with the Other Hydrated Divalent Alkaline Earth Metal Ions

The thermodynamic properties and electronic structure of hydrated Ra2+ have been investigated using ab initio quantum chemical calculations that apply the relativistic model core potential method and compared with those of the other hydrated divalent alkaline earth metal ions (Mg2+, Ca2+, Sr2+, and Ba2+). The solvation free energies calculated for [Ra (H2O)n]2+ (n = 1–9) in a continuum dielectric media (semi-continuum model) showed that the hydration number of Ra2+ is in the range of 7–9. Natural population analysis (NPA), natural bond orbital (NBO) analysis and localized molecular orbital energy decomposition analysis (LMO-EDA) showed that the dominant interaction between hydrated Ra2+ ions and solvent water molecules is electrostatic interaction to form coordination bonds which have a strong ionic bond character. On the other hand, not only electrostatic interaction but also covalent interaction accompanying charge-transfer from solvent water molecules to the central ion are important in the interaction between hydrated Mg2+ or Ca2+ (lighter divalent alkaline earth metal ions) and solvent water molecules.