Theoretical studies on the nature and strength of an intermolecular non-covalent Te•••π interaction (original) (raw)
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Chemical Physics Letters, 2004
Several complexes of benzene with cations and hexafluorobenzene with anions have been optimized at the MP2/6-31++G**, B3LYP/6-31++G** and HF/6-31++G** levels of theory. Different aspects of the cation-p interaction have been compared to those of anion-p, including changes in the aromaticity of the ring upon complexation, charge-transfer effects using the Merz-Kollman charges and the contribution of dispersion energies by comparing the complexation energies computed at the B3LYP and MP2 levels of theory.
Journal of the American Chemical Society, 2001
The nature and origin of the π-H interaction in both the ethene (olefinic) and benzene (aromatic) complexes of the first-row hydrides (BH 3 , CH 4 , NH 3 , H 2 O, and HF) has been investigated by carrying out high level ab initio calculations. The results indicate that the strength of the π-H interaction is enhanced as one progresses from CH 4 to HF. Unlike conventional H-bonds, this enhancement cannot be simply explained by the increase in electrostatic interactions or the electronegativity of the atom bound to the π H-bonded proton. The contributions of each of the attractive (electrostatic, inductive, dispersive) and repulsive exchange components of the total binding energy are important. Thus, the inductive energy is highly correlated to the olefinic π-H interaction as we progress from CH 3 to HF. On the other hand, both electrostatic and inductive energies are important in the description of the aromatic π-H interaction. In either case, the contribution of dispersion energies is vital to obtain an accurate estimate of the binding energy. We also elaborate on the correlation of various interaction energy components with changes in geometries and vibrational frequencies. The red-shift of the ν Y-H mode is highly correlated to the inductive interaction. The dramatic increase in the exchange repulsion energies of these π complexes as we progress from CH 4 to HF can be correlated to the blue-shift of the highly IR active out-of-plane bending mode of the π system.
Journal of Computational Chemistry, 2005
Intermolecular interaction energy decompositions using the Constrained Space Orbital Variation (CSOV) method are carried out at the Hartree–Fock level on the one hand and using DFT with usual GGA functionals on the other for a number of model complexes to analyze the role of electron correlation in the intermolecular stabilization energy. In addition to the overall stabilization, the results provide information on the variation, with respect to the computational level, of the different contributions to the interaction energy. The complexes studied are the water linear dimer, the N-methylformamide dimer, the nucleic acid base pairs, the benzene–methane and benzene-N2 van der Waals complexes, [Cu+-(ImH)3]2, where “ImH” stands for the Imidazole ligand, and ImH-Zn++. The variation of the frozen core energy (the sum of the intermolecular electrostatic energy and the Pauli repulsion energy) calculated from the unperturbed orbitals of the interacting entities indicates that the intramolecular correlation contributions can be stabilizing as well as destabilizing, and that general trends can be derived from the results obtained using usual density functionals. The most important difference between the values obtained from HF and DFT computations concerns the charge transfer contribution, which, in most cases, undergoes the largest increase. The physical meaning of these results is discussed. The present work gives reference calculations that might be used to parametrize new correlated molecular mechanics potentials. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 1052–1062, 2005
Cation-π vs anion-π interactions: a complete π-orbital analysis
Chemical Physics Letters, 2004
A complete orbital analysis of two isoelectronic complexes of trifluorobenzene (TFB), TFB Á Á Á F À and TFB Á Á Á Na + , as models for anion-p and cation-p interactions, respectively, has been performed at the MP2/6-31++G** level of theory. There are important orbital differences between both interactions, which are discussed in detail herein.
Theoretical Study on Cooperativity Effects between Anion-π and Halogen-Bonding Interactions
ChemPhysChem, 2011
This article analyzes the interplay between lone pair-π (lp-π) or anion-π interactions and halogen-bonding interactions. Interesting cooperativity effects are observed when lp/anion-π and halogen-bonding interactions coexist in the same complex, and they are found even in systems in which the distance between the anion and halogen-bond donor molecule is longer than 9 Å. These effects are studied theoretically in terms of energetic and geometric features of the complexes, which are computed by ab initio methods. Bader's theory of "atoms in molecules" is used to characterize the interactions and to analyze their strengthening or weakening depending upon the variation of charge density at critical points. The physical nature of the interactions and cooperativity effects are studied by means of molecular interaction potential with polarization partition scheme. By taking advantage of all aforementioned computational methods, the present study examines how these interactions mutually influence each other. Additionally, experimental evidence for such interactions is obtained from the Cambridge Structural Database (CSD).
Journal of molecular modeling, 2017
This theoretical work exhibits a new systematic study of structural parameters, electronic properties, infrared vibration modes, and molecular topography of hydrogen complexes, namely linear-type HCN⋯HX and T-type C2H2⋯HX (X = F, Cl, CN, and CCH). Ideally, the knowledge of the ternary systems of C2H2⋯HCN⋯HF and HCN⋯HCN⋯HF whose subparts integrate the linear and T-shaped complexes were used to give support in this current research. By means of computational calculations carried out in both levels B3LYP and MP2, the variations of the HX bond lengths are clearly overestimated in the HCN⋯HX linear complexes. In agreement with the analyses of the electrostatic potentials, the higher intermolecular energies of these complexes agree with the larger red-shifts in the stretch frequencies in HX. Also, the QTAIM descriptors and NBO calculations were used to inspect the interaction strength as well as to confirm the π cloud as a proton accepting center. By taking into account the absorption int...
A valence bond theory treatment of tetrel bonding interactions
Computational and Theoretical Chemistry, 2017
Long range noncovalent interactions in H 3 Y … TrH 3 X molecules (Y = N, P, As; Tr = C, Si, Ge; X = F, Cl, Br) have been studied using valence bond methods in order to further the understanding of tetrel (group IV) bonding. It is shown that incorporating electron correlation through the breathing orbital valence bond method is required in order to reproduce tetrel bond energy trends obtained by density functional theory. Tetrel bonds are formed by donation of the Y lone pair into a -hole on the Tr atom and their strength depends on the donor strength of the Y atom and the Tr/X electronegativity difference. Charge transfer valence bond structures are shown to be important, indicating that electron transfer is the driving force behind tetrel bonds rather than electrostatics.