EDA Analysis Research Articles

Theoretical studies of group 10 metal gallylene complexes [TM(CO)3(GaX)

Reaction and electronic structural analysis of transition metal carbonyls [TM(CO)3] and corresponding gallylene complexes [(CO)3TM(GaX)] were investigated theoretically at the DFT/B3LYP/6-31G*/LANL2DZ level of theory. From the NBO analysis, the orbital interactions of metal to gallium, and the partial atomic charges were analysed. From the EDA analysis, various parameters like ΔEPauli, ΔEorb and ΔEelstat were calculated for the transition metal to GaX bonds. And we have predicted the increasing order of TM, Pd < Ni < Pt. We have studied the formation of complexes [(CO)3TM(GaX)] via five-member coordinated transition state and we have found that the complexes are feasible.

Exceptional bifurcated chalcogen bonding interaction between Ph2N2O2 and only one σ–hole on XCY (X=S, Se, Te and Y=O, S, Se, Te): a DFT study

Quantum chemical calculations are performed to study the bifurcated chalcogen bonding (BCB) interactions in Ph2N2O2…XCY (X=S, Se, Te and Y=O, S, Se, Te) complexes. The interaction of the only one σ-hole on X atom with two negative regions, which leads to BCB interactions, is exceptionally remarkable. The nature of the BCB interactions is probed by a variety of means, including electrostatic potentials, AIM, NBO, energy decomposition and electron density differences maps. The EDA analysis reveals that the dominant attractive force in X…O chalcogen bonded complexes is the electrostatic energy. The interaction energy values, obtained using the QTAIM-based Espinosa’s approach, provide a relatively distinguishable result than DFT method and EDA analysis reported in this study.

Coordination of indium monohalide with group-10 metal carbonyls [TM(CO)3(InX)]: a DFT study

A DFT study carried out on the diatomic ligand of InX coordinated with metal carbonyls [TM(InX)(CO)3] (TM = Ni, Pd, and Pt) using B3LYP, CAM-B3LYP, M06-2X level of theories with the basis sets 6-31G*, 6-311G**, LANL2DZ, and SDD. The NBO analysis confirms the π bonding contribution is lesser than that of σ (sigma) bonding contribution in TM–InX bond and it emphasizes the greater contribution by the indium atom. The orbital interactions occur between indium and the transition metal (TM) via σ donation TM ← InX. The WBI analysis acknowledges that the TM = InX bonds are stronger than the TM–CO bonds. The energy gap between the HOMO–LUMO is predicted by FMO analysis. The EDA analysis confirms that the ΔEelstat (electrostatic interaction) is more than that of ΔEorb (covalent bonding) of the complexes.

Shedding light on the bonding situation of triangular and square heterometallic clusters: computational insight

DFT calculations reproduced the experimentally observed out-of-plane distortions in heterometallic clusters [MMoCp(CO)3]n (M = Cu+, Ag+ or Au+, n = 3 or 4); (Cp = η5-C5H5), while EDA analysis gives new insights into bonding situations.

A serendipitous isolation of cocrystallized platinum–tin complexes: synthesis, structure and theoretical exploration

An adduct of co-crystallized platinum–tin fragments has been synthesized and characterized. NBO and EDA analysis have been performed to explore the nature of bonding in fragments, especially the extent of oxophilic character present in tin atoms.

DFT Investigation of a Charge-Transfer Complex Formation Between p-Phenylenediamine and 3,5-Dinitrosalicylic Acid

This study presents a computational investigation of p-phenylenediamine (PPD) interaction with 3,5-dinitrosalicylic acid (DNS) within PPD/DNS charge transfer (CT) complex. All calculations were performed by M06-2X/6-311+G(d,p) levels of theory in vacuum, water and methanol. EDA analysis was used to control the complexation process and suggested that electrostatic and dispersion energies contributes greatly in stabilizing PPD/DNS CT complex. The results of energy optimization showed that PPD/DNS CT complex is stable with negative complexation energy; the obtained geometries showed that ammonium group of PPD is closed to carboxylate one of DNS enabling the establishment of large number of interactions. Additionally, different analyses were performed on obtained optimized structures: TD-DFT, NBO, QTAIM and NCI. Consequently, NBO, QTAIM and NCI analysis give that PPD/DNS CT complex is stabilized by hydrogen bonding and van der Waals interactions.

DFT investigation of a charge-transfer complex formation between p-phenylenediamine and 3,5-dinitrosalicylic acid

This study presents a computational investigation of p-phenylenediamine (PPD) interaction with 3,5-dinitrosalicylic acid (DNS) within a PPD/DNS charge-transfer (CT) complex. All calculations are performed at M06-2X/6-311+G(d,p) levels of theory in vacuum, water, and methanol. The EDA analysis is used to control the complexation process and it suggests that electrostatic and dispersion energies contribute greatly to the stabilization of the PPD/DNS CT complex. The results of the energy optimization show that the PPD/DNS CT complex is stable with a negative complexation energy. The obtained geometries reveal that the PPD ammonium group is close to the DNS carboxylate one, enabling the establishment of a large number of interactions. Additionally, different analyses are performed on the obtained optimized structures: TD-DFT, NBO, QTAIM, and NCI. Consequently, NBO, QTAIM and NCI analyses give that the PPD/DNS CT complex is stabilized by the hydrogen bonding and van der Waals inter­actions.

New complexes of Ni(II) and Cu(II) with tridentate ONO Schiff base ligand: synthesis, crystal structures, electrochemical and theoretical investigation

In this research, we prepared a new series of the Cu(II) (1) and Ni(II) (2) metal complexes of a tridentate Schiff base ligand, (E)-2-(5-bromo-2-hydroxybenzylideneamino) phenol (H2L). These complexes were characterized by elemental analysis, FT-IR, UV–Vis, and 1H-NMR spectroscopy. The crystal structures of (1) and (2) were determined by X-ray diffraction studies. The single crystal X-ray diffraction analyses revealed that copper(II) cation is five-coordinated and the coordination polyhedron is a slightly distorted square pyramid. Nickel(II), on the other hand, is four-coordinated, and has a regular, square planar geometry. Further discussed were the electrochemical reduction of these complexes. We also analyzed the nature of the metal–ligand bond in the complexes through NBO and EDA analysis. Besides, vibrational sample magnetometer (VSM) revealed complex (1) was ferromagnetic.

Unravelling the nature of binding of cubane and substituted cubanes within cucurbiturils: A DFT and NCI study

The nature of interactions between the neutral, charged and substituted cubane, within cucurbituril host were analyzed employing the dispersion corrected density functional theory. The structural comparison between the inclusion complexes of CB7 and CB8 shows a best fit for the CB7. The computed Gibbs free energy for the formation of inclusion complexes by the neutral guests were close to the experimental estimate. The dicationic guest within CB has the highest strain energy with least strain on the host. The conceptual DFT based analysis ECT analysis shows a charge transfer from the host to guest in neutral systems, while for the dicationic guest an electron transfer from guest to host has been noticed, which was further conformed from the quantitative MESP values. The computed NICS values on the cubane, are not affected by the introduction of charge/substituents implying that cubane part act as a spacer group while the functional groups present on the cubane dictates the charge transfer. In AIM analysis, the ρ value is least for the complex cubane@CB7 and highest for the cubane functionalized dicationic complex@CB complexes. The NCI-RDG analysis for the inclusion complex with dicarboxylic guest, the spike at higher density region undergoes a shift, reflecting the increase in repulsive energy. In the inclusion complexes of CB7 the patch escalation in the NCI isosurface occurs evenly in CB7 than on the CB8 inclusion complexes, signifying the fit-induced extra stability of the CB7 inclusion complexes. EDA analysis shows that the Pauli repulsive energy increase with the increase in the size of the guest molecule and among the guest the dicationic has the highest repulsive energy. The presence of higher amount of electrostatic interactions in the dicationic complex has remunerated the dispersion contribution in the dicationic complexes.

Noncovalent Interactions in Succinic and Maleic Anhydride Derivatives

Herein, we present a study of the short contacts that several heterocycles of the same family, namely, succinic and maleic anhydrides, maleimide, and succinimide establish in their condensed phases. DFT calculations on model systems in the gas phase have allowed us to calibrate the strength of such interactions, obtaining associated energies up to 2 kcal/mol. We have performed MEP and EDA analysis to unveil their nature, which is mainly electrostatic with some London dispersion contribution. Furthermore, the origin of the interaction is the existence of a charge depletion region (a π-hole) in the inner part of the rings. This hole interacts with a Lewis base in a precise topological way, with the contacts showing a high directionality as revealed by the analysis of hundreds of crystal structures. We believe that the description for the first time of these interactions, along with their abundance, can assist their use as a tool in crystal design.

Intermolecular interaction in nucleobases and dimethyl sulfoxide/water molecules: A DFT, NBO, AIM and NCI analysis

This study aims to cast light on the physico-chemical nature and energetics of interactions between the nucleobases and water/DMSO molecules which occurs through the non-conventional CH⋯O/N−H bonds using a comprehensive quantum-chemical approach. The computed interaction energies do not show any appreciable change for all the nucleobase-solvent complexes, conforming the experimental findings on the hydration enthalpies. Compared to water, DMSO form complexes with high interaction energies. The quantitative molecular electrostatic potentials display a charge transfer during the complexation. NBO analysis shows the nucleobase-DMSO complexes, have higher stabilization energy values than the nucleobase-water complexes. AIM analysis illustrates that the in the nucleobase-DMSO complexes, SO⋯H-N type interaction have strongest hydrogen bond strength with high EHB values. Furthermore, the Laplacian of electron density and total electron density were negative indicating the partial covalent nature of bonding in these systems, while the other bonds are classified as noncovalent interactions. EDA analysis indicates, the electrostatic interaction is more pronounced in the case of nucleobase-water complexes, while the dispersion contribution is more dominant in nucleobase-DMSO complexes. NCI-RDG analysis proves the existence of strong hydrogen bonding in nucleobase-DMSO complex, which supports the AIM results.

Extractive desulfurization of liquid fuel by using a green, neutral and task specific phosphonium ionic liquid with glyceryl moiety: A joint experimental and computational study

A phosphonium ionic liquid with glyceryl moiety was synthesized and used as an efficient extractant in the removal of sulfur compounds from a model liquid fuel. The effects of different parameters such as volume ratio, time, initial concentration, temperature and type of sulfur compound on the desulfurization efficiency were investigated. The reusability and the recyclability of the described ionic liquid in the extractive desulfurization were also studied. For comparison, another ionic liquid with two acidic moieties was synthesized and used in the extractive desulfurization. To understand the mechanism of the extractive desulfurization by the phosphonium ionic liquid, a computational study consisting of structural investigations, interaction energy, NBO, AIM and EDA analysis on the type and nature of the interaction between dibenzothiophene (DBT) and the prepared ionic liquid was also performed. The obtained results of this research support the idea of rational design, synthesis and application of the task specific extractants for the green desulfurization of liquid fuels.

Synthesis and characterization of two new N4O2 macroacyclic Schiff-base ligands containing piperazine moiety and mononuclear Co(III) and Cu(II) complexes, spectral, X-ray crystal structural, theoretical studies, cytotoxic and antibacterial properties

Two new Schiff base ligands, H2L1 and H2L2, have been prepared from the condensation of 2-hydroxybenzaldehyde or 2-hydroxy-3-methoxybenzaldehyde with 2,2′-(piperazine-1,4-diylbis (methylene))dianiline (A1), respectively. In the presence of appropriate metal ions and in methanolic/ethanolic solution four Cobalt(III) and Copper(II) macroacyclic Schiff-base complexes were prepared. All resultant products were characterized by elemental analysis, mass spectrometry and spectroscopic methods such as: FT-IR, 1H and 13C NMR. In addition the crystal structures of [CoL1](ClO4) and [CoL2](ClO4)(CH3CN) complexes have been revealed by single-crystal X-ray crystallography. The cytotoxic and antibacterial properties of some of complexes were studied. The geometries of the [CoL1]+ and [CoL2]+ complexes have been optimized at the BP86/def2-SVP level of theory. Also the nature of the metal–ligand bond in the complexes is analyzed with NBO and EDA analysis. Results confirm that the nature of metal–ligand bond in the complexes is slightly more covalent with a contribution of about 53% in total interaction energies.

Linear σ‐Hole Bonding Dimers and Trimers Between Dihalogen Molecules XY (X, Y=Cl, Br) and Carbon Monoxide

AbstractIntermolecular interactions between CO and dihalogen molecules XY (X, Y=Cl, Br) were investigated at MP2/aug‐cc‐pVDZ level without and with counterpoise method, and single point calculations at CCSD(T)/aug‐cc‐pVDZ level were performed. XY can interact with one or two CO to form linear σ‐hole bonding dimer or trimer. Their optimized geometries, stretching modes and interaction energies were investigated. The X⋅⋅⋅C (or Y⋅⋅⋅C) interaction is stronger and more competitive than X⋅⋅⋅O (or Y⋅⋅⋅O) interaction, so the OC⋅⋅⋅X−Y⋅⋅⋅CO complex is stronger and more competitive than the CO⋅⋅⋅X−Y⋅⋅⋅OC complex. The interaction strengths of trimeric complexes are dependent upon the property of XY, andthe anticooperative or diminutive effects were observed for them. Electrostatic interaction is the dominant net driving force for the formation of these dimers based on EDA analysis. The formation of two linear halogen bonds in each trimer was identified by bond paths and green circle isosurfaces appearing between the halogen and C (or O) atoms. The results would provide valuable insight into the competition and cooperativity of linear halogen bonds.

Trapping of organophosphorus chemical nerve agents by pillar[5]arene: A DFT, AIM, NCI and EDA analysis

The encapsulation of organophosphorus (OP) nerve agents by pillar[5]arene (P5) molecule, shows that adsorption occurs with a larger structural reorganization of the host molecule. The computed binding energies shows that the complexes formed are more stable inside the cavity. Tabun was found to have the highest binding energy among the studied OPs. The computed Gibbs free energy is negative for Dimethyl methylphosphonate, sarin and tabun, and are positive for soman (GD) and ethyl-S-dimethylaminoethyl methylphosphonothiolate (VX). The inclusion complexes were found to have lower band gap. The quantum theory of Atoms-in-molecules analysis shows that ρ values were positive which implies the existence of noncovalent interactions. The Laplacian of the charge density ∇2ρ for bond critical points bonds are small and are negative which indicates the depletion of electronic charge along the bond paths and existence of an electrostatic nature of bonding between the guest and host molecule. The noncovalent interactions analysis clearly shows the existence of hydrogen bonding and van der Waals bonding in these inclusion complexes. The energy decomposition analysis shows that the, interaction between the P5 and the larger guest molecules VX and GD are mainly due to electrostatic interaction and for small guest, the interactions are mostly of van der Waals type.

Key role of higher order symmetry and electrostatic ligand field design in the magnetic relaxation of low-coordinate Er(iii) complexes.

The conceptual framework of electrostatic ligand field modulation based on oblate/prolate type electron density of lanthanide ions is one of the most successful approaches to enhance barrier height in lanthanide-based single-ion magnets. Recently, a tetra coordinated [Er{N(SiMe3)2}s3Cl]·2THF (1) complex with an unfavourable ligand field showed slow relaxation of magnetization in zero field and challenges the concept of electrostatic ligand field modulation. To unravel the magnetic relaxation in this complex, we carried out a detailed theoretical investigation on three Er(iii) complexes belonging to the same family of single-ion magnets. The CASSCF/PT2 + RASSI-SO approach highlights that the concept of electrostatic ligand field modulation based on oblate/prolate type is still valid in these complexes, and the relaxation dynamics observed can be rationalized by accounting for both the symmetry and geometrical distortions around the Er(iii) ion. Using ab initio computed blockade barriers and crystal field analysis, we analysed the key components of the magnetic relaxation. Our study suggests that in these structures, the Er(iii) ion shifted out of the triangular plane formed by the three nitrogen donor atoms and this out-of-plane shift (τ) significantly influences the slow-relaxation of magnetization. In order to gain deeper insights into the nature of metal-ligand bonding, and to predict quantitatively the strength of the axial and equatorial ligand field, ELF, QTAIM, and EDA analysis were carried out in these complexes. Our findings highlight that the molecules possessing large barrier height for magnetic relaxation are due to the combined effect of a favourable ligand field and the symmetry around the Er(iii) ion. To understand the intricate role of both effects, several robust magneto-structural correlations were developed. Besides, the lanthanide-halogen covalency was also found to play a vital role in controlling the magnetic anisotropy and thus the magnetic relaxation. A near linear trend was observed between the calculated barrier height and the increase in the Er-X covalency as we move from -F to -I. This offers a de novo approach to increase barrier height in mononuclear lanthanide based complexes.

Phenylacetylene–water complex: Is it n⋯σ or H⋯π in the matrix?

Hydrogen bonded complexes of phenylacetylene (PhAc) and water were studied using matrix isolation infrared spectroscopy and ab initio computations. In this work, we have for the first time identified the n⋯σ complex, in N2 and Ar matrixes. Earlier experiments on the PhAc-H2O system, using molecular beams, had observed only the H⋯π complex, where H2O was the proton donor to the acetylenic π cloud of PhAc, and which was indicated by computations, to be the global minimum. Computations also located two other minima on the PhAc-H2O potential surface. The technique of matrix isolation, which is known to trap local minima, was used to investigate the PhAc-H2O system, in an attempt to observe any of the local minima, which were not observed in the gas phase experiments. Our experiments, using both Ar and N2 matrixes, provided unambiguous evidence for the formation of the n⋯σ complex, a local minimum. Experiments with D2O and phenylacetylene deuterated at the acetylenic hydrogen (PhAcD) were also performed, to confirm the above observation, through the isotopic effect. Rather surprisingly, we were unable to observe any evidence for the global minimum in these experiments. The phenylacetylene-water system was theoretically investigated, employing MP2 and DFT (B3LYP, M06-2X, ωB97XD) methods, with 6-311++G** and aug/cc-pVDZ basis sets. AIM, EDA and NBO analysis were also performed to explore the nature, physical origin and the strength of noncovalent interactions.

Complexes of XeHXe⁺ with simple ligands: a theoretical investigation on (XeHXe⁺)L (L = N₂, CO, H₂O, NH₃).

The structure, stability, and harmonic frequencies of the (XeHXe(+))L complexes (L = N2, CO, H2O, NH3) were investigated by ab initio and density functional theory (DFT) calculations. Their bonding situation was also assayed by natural bond orbital (NBO), atoms-in-molecules (AIM), and energy decomposition (EDA) analyses. For any L, we located a linear and a T-shaped isomer, whose energy difference progressively increases in the order N2 < CO < H2O < NH3 and ranges from nearly 0 to 4.5 kcal mol(-1). The absolute complexation energies of both the linear and the T-shaped isomers also increase in the same order, and their EDA analysis revealed the prevailing contribution of electrostatic interactions. The noncovalent character of the bonding between XeHXe(+) and L was confirmed by the AIM analysis. In particular, we based our investigation on the joint use of numerical AIM indices and graphic examination of the local Hamiltonian kinetic energy density, K(r). Interestingly, this function visually identifies the "covalent" regions occupied by XeHXe(+) and L and the "noncovalent" zones existing between them, which include, in particular, the bond critical point located on the Xe-L bond paths. Only for the linear (XeHXe(+))NH3 did the AIM analysis suggest an onset of covalency in the xenon-nitrogen interaction. Further work is in progress to examine the effectiveness of K(r), and its plotted forms, as a function of the bonding situation of noble-gas compounds.

Palladium(II) Complexes of 1,2,4-Triazole-BasedN-Heterocyclic Carbenes: Synthesis, Structure, and Catalytic Activity

Six palladium(II) complexes bearing three different triazole-based N-heterocyclic carbene (NHC) ligands, [1-tert-butyl-4-{2-[(N,N-dimethylamino)methyl]phenyl}-3-phenyl-1H-1,2,4-triazol-4-ium-5-ide, 1-tert-butyl-4-(2-methoxyphenyl)-3-phenyl-1H-1,2,4-triazol-4-ium-5-ide, and 1-tert-butyl-4-(4-methylphenyl)-3-phenyl-1H-1,2,4-triazol-4-ium-5-ide], were synthesized and fully characterized. NMR spectroscopy and X-ray diffraction analysis revealed that the amino-group-substituted NHC ligand is coordinated in bidentate fashion, forming a monocarbene chelate complex with an additional intramolecular Pd ← N bond with the nitrogen donor atom. The 4-methylphenyl- and 2-methoxyphenyl-substituted NHC ligands coordinate as C-monodentate donors, forming simple biscarbene Pd(II) complexes. The evaluation of the catalytic performance in the Suzuki–Miyaura cross-coupling reaction revealed very promising performance of the intramolecularly coordinated monocarbene complexes under relatively mild conditions even in direct comparison with the commercially available PEPPSI catalyst. In contrast, the biscarbene complexes proved inactive in this catalytic process. According to theoretical calculations (EDA and NOCV analysis), functionalization of the 1,2,4-triazole-based NHC with the 2-[(N,N-dimethylamino)methyl]phenyl group has a significant effect on the stability of the NHC–metal bond.

DFT studies of imino and thiocarbonyl ligands with the pentaaqua Mg2+ cation: affinity and associated parameters

The affinity of the pentaaqua Mg(2+) cation for a set of para-substituted imino [HN = CHC₆H₄(R)] and thiocarbonyl [S = CHC₆H₄(R)] ligands (R = H, F, Cl, Br, OH, OCH₃, CH₃, CN, NH₂ and NO₂) was analyzed with DFT (B3LYP/6-31+G(d)) and semi-empirical (PM6-DH2) methods. The interaction enthalpy was calculated to quantify the affinity of the Mg(2+) cation for the ligands. Additionally, geometric and electronic parameters were correlated with the intensity of the metal-ligand interaction. The imino ligands have stronger interaction with the pentaaqua Mg(2+) cation than the thiocarbonyl derivatives. The electronic nature of the substituent is the main parameter that determines the interaction enthalpy. Ligands with electron donor substituents have more exothermic interaction enthalpies than those with electron withdrawing groups. The HSBA analysis showed that the interaction between the Mg(2+) cation and hard bases (imino ligands) is stronger than with soft bases (thiocarbonyl derivatives). The EDA analysis showed that the electrostatic, covalent and repulsion components of the interaction are the most affected by the substituent, whereas the dispersion and exchange components are almost constant.