Origin and Nature of Lithium and Hydrogen Bonds to Oxygen, Sulfur, and Selenium
01 Nov 2000-Journal of Physical Chemistry A (American Chemical Society)-Vol. 104, Iss: 46, pp 10859-10867
TL;DR: In this article, LiF and hydrogen bonded complexes with H2CO, H2CS, and H2CSe have been investigated using higher level ab initio calculations and extensive searches of the potential energy surfaces for equilibrium structures have been done at the Hartree−Fock level, and post Hartree-Fock calculations at MP2, MP4 levels and DFT calculations with B3LYP functional have been performed on the stable forms.
Abstract: Lithium and hydrogen bonded complexes of LiF and HF with H2CO, H2CS, and H2CSe have been investigated using higher level ab initio calculations. Extensive searches of the potential energy surfaces for equilibrium structures have been done at the Hartree−Fock level, and post Hartree−Fock calculations at MP2, MP4 levels and DFT calculations with B3LYP functional have been performed on the stable forms. 6-311++G(d,p) and 6-31++G(d,p) basis sets on H, C, O, and S and 6-311++G(d,p) basis set on Se have been employed throughout. NBO analysis of the wave functions have been done to trace the origin of various interactions that stabilize the complexes. Harmonic frequencies computed at Hartree−Fock level show that, of the 10 proposed structures, LiF and HF complexes have three and one stable forms, respectively. Potential energy surface features, structure, and stability of LiF complexes are completely different from those of HF complexes. Though it is commonly observed that lithium and hydrogen bonding interactio...
TL;DR: A detailed Atoms in Molecules (AIM) theoretical analysis confirms an important conclusion: there is a strong correlation between the electron density at the XA bond critical point (BCP) and the interaction energy for all these interactions.
Abstract: One hundred complexes have been investigated exhibiting D–X⋯A interactions, where X = H, Cl or Li and DX is the ‘X bond’ donor and A is the acceptor. The optimized structures of all these complexes have been used to propose a generalized ‘Legon–Millen rule’ for the angular geometry in all these interactions. A detailed Atoms in Molecules (AIM) theoretical analysis confirms an important conclusion, known in the literature: there is a strong correlation between the electron density at the X⋯A bond critical point (BCP) and the interaction energy for all these interactions. In addition, we show that extrapolation of the fitted line leads to the ionic bond for Li-bonding (electrostatic) while for hydrogen and chlorine bonding, it leads to the covalent bond. Further, we observe a strong correlation between the change in electron density at the D–X BCP and that at the X⋯A BCP, suggesting conservation of the bond order. The correlation found between penetration and electron density at BCP can be very useful for crystal structure analysis, which relies on arbitrary van der Waals radii for estimating penetration. Various criteria proposed for shared- and closed-shell interactions based on electron density topology have been tested for H/Cl/Li bonded complexes. Finally, using the natural bond orbital (NBO) analysis it is shown that the D–X bond weakens upon X bond formation, whether it is ionic (DLi) or covalent (DH/DCl) and the respective indices such as ionicity or covalent bond order decrease. Clearly, one can think of conservation of bond order that includes ionic and covalent contributions to both D–X and X⋯A bonds, for not only X = H/Cl/Li investigated here but also any atom involved in intermolecular bonding.
TL;DR: In this paper, high-level G2(MP2) ab initio and B3LYP/6-311+G(3df,2p) density functional calculations have been carried out for a series of β-chalcogenovinylaldehydes, HC(X)−CHCH−CYH (X = O, S; Y = Se, Te).
Abstract: High-level G2(MP2) ab initio and B3LYP/6-311+G(3df,2p) density functional calculations have been carried out for a series of β-chalcogenovinylaldehydes, HC(X)−CHCH−CYH (X = O, S; Y = Se, Te). Our results indicate that for X = O, S and Y = Se, the O−H···Se and the S−H···Se intramolecular hydrogen bonds compete in strength with the O···Se and the S···Se interaction, while the opposite is found for the corresponding tellurium-containing analogues. The different strength of O−H···Se and O···H−Se intramolecular hydrogen bonds explains why the chelated enolic and keto forms of selenovinylaldehyde are very close in energy, although enol-tautomers are estimated to be about 10 kcal mol-1 more stable than keto-tautomers. The situation is qualitatively similar for selenothiovinylaldehyde, although the S−H···Se and S···H−Se intramolecular hydrogen bonds (IHBs) are weaker and much closer in strength, and the energy gap between enethiol- and thione-tautomers also smaller. The relative strengths of the X−H···Te and X···...
TL;DR: In this article, the interaction energies of the dimethylsulfide-methanol (I) and dimethylthiocarbonyl-methylthiol (II) complexes are calculated as a function of the S⋯H-O distances at various levels of theory and compared to those of their oxygen analogs.
Abstract: The interaction energies of the dimethylsulfide–methanol (I) and dimethylthiocarbonyl–methanol (II) complexes are calculated as a function of the S⋯H–O distances at various levels of theory and compared to those of their oxygen analogs. At the coupled cluster level the binding energy of (I) is −5.46 kcal/mol, only slightly smaller than the hydrogen bond energy of −5.97 kcal/mol for the corresponding oxygen analog, i.e., the dimethylether–methanol complex. It is also considerably larger than for dimethylether–methylthiol, where S and O of the parent complex are interchanged. Density functional theory is unable to describe these weak interactions properly. Choosing second-order Moller–Plesset perturbation theory, the interaction potential surfaces of both complexes with respect to the three relevant intermolecular coordinates are compared. The interactions in the hydrogen bonds involving sulfur are classified by Morokuma, atoms-in-molecules, and natural bond orbital analyses.
TL;DR: The hydrogen bond interaction and σ-hole and π-hole bonds are steered by the same mechanisms and the increase of the polarization of bonds to this centre seems to be the common effect.
Abstract: The hydrogen bond interaction and σ-hole and π-hole bonds are steered by the same mechanisms. There is electron charge transfer from the Lewis base to the Lewis acid unit, and further, for various interactions the same mechanisms try to protect the former electronic structure of the Lewis acid centre. The increase of the polarization of bonds to this centre seems to be the common effect. In the case of the A-HB hydrogen bond it is the increase of the polarization of the A-H bond connected with the outflow of the electron charge from the H-atom to the A-centre. For other interactions the outflow of electron charge from the Lewis acid centre is also observed. These electron charge shifts try to protect the doublet/octet structure of the acidic centre. The extremely strong interaction is often equivalent to the formation of new covalent bonds or it may lead to chemical reactions. Numerous interactions may be treated as the preliminary stages of chemical reactions: hydrogen bond - proton transfer, dihydrogen bond - molecular hydrogen release, tetrel bond - SN2 reaction, etc.
TL;DR: This paper suggested some measures for enhancing the strength of the halogen bond relative to the hydrogen bond in the H(2)CS-HOX (X = F, Cl, and Br) system by means of quantum chemical calculations.
Abstract: The properties and applications of halogen bonds are dependent greatly on their strength. In this paper, we suggested some measures for enhancing the strength of the halogen bond relative to the hydrogen bond in the H2CS–HOX (X = F, Cl, and Br) system by means of quantum chemical calculations. It has been shown that with comparison to H2CO, the S electron donor in H2CS results in a smaller difference in strength for the Cl halogen bond and the corresponding hydrogen bond, and the Br halogen bond is even stronger than the hydrogen bond. The Li atom in LiHCS and methyl group in MeHCS cause an increase in the strength of halogen bonding and hydrogen bonding, but the former makes the halogen bond stronger and the latter makes the hydrogen bond stronger. In solvents, the halogen bond in the Br system is strong enough to compete with the hydrogen bond. The interaction nature and properties in these complexes have been analyzed with the natural bond orbital theory.
TL;DR: In this article, a semi-empirical exchange correlation functional with local spin density, gradient, and exact exchange terms was proposed. But this functional performed significantly better than previous functionals with gradient corrections only, and fits experimental atomization energies with an impressively small average absolute deviation of 2.4 kcal/mol.
Abstract: Despite the remarkable thermochemical accuracy of Kohn–Sham density‐functional theories with gradient corrections for exchange‐correlation [see, for example, A. D. Becke, J. Chem. Phys. 96, 2155 (1992)], we believe that further improvements are unlikely unless exact‐exchange information is considered. Arguments to support this view are presented, and a semiempirical exchange‐correlation functional containing local‐spin‐density, gradient, and exact‐exchange terms is tested on 56 atomization energies, 42 ionization potentials, 8 proton affinities, and 10 total atomic energies of first‐ and second‐row systems. This functional performs significantly better than previous functionals with gradient corrections only, and fits experimental atomization energies with an impressively small average absolute deviation of 2.4 kcal/mol.
TL;DR: Numerical calculations on a number of atoms, positive ions, and molecules, of both open- and closed-shell type, show that density-functional formulas for the correlation energy and correlation potential give correlation energies within a few percent.
Abstract: A correlation-energy formula due to Colle and Salvetti [Theor. Chim. Acta 37, 329 (1975)], in which the correlation energy density is expressed in terms of the electron density and a Laplacian of the second-order Hartree-Fock density matrix, is restated as a formula involving the density and local kinetic-energy density. On insertion of gradient expansions for the local kinetic-energy density, density-functional formulas for the correlation energy and correlation potential are then obtained. Through numerical calculations on a number of atoms, positive ions, and molecules, of both open- and closed-shell type, it is demonstrated that these formulas, like the original Colle-Salvetti formulas, give correlation energies within a few percent.
TL;DR: In this paper, a direct difference method for the computation of molecular interactions has been based on a bivariational transcorrelated treatment, together with special methods for the balancing of other errors.
Abstract: A new direct difference method for the computation of molecular interactions has been based on a bivariational transcorrelated treatment, together with special methods for the balancing of other errors. It appears that these new features can give a strong reduction in the error of the interaction energy, and they seem to be particularly suitable for computations in the important region near the minimum energy. It has been generally accepted that this problem is dominated by unresolved difficulties and the relation of the new methods to these apparent difficulties is analysed here.
TL;DR: In this article, a contract Gaussian basis set (6•311G) was developed by optimizing exponents and coefficients at the Mo/ller-Plesset (MP) second-order level for the ground states of first-row atoms.
Abstract: A contracted Gaussian basis set (6‐311G**) is developed by optimizing exponents and coefficients at the Mo/ller–Plesset (MP) second‐order level for the ground states of first‐row atoms. This has a triple split in the valence s and p shells together with a single set of uncontracted polarization functions on each atom. The basis is tested by computing structures and energies for some simple molecules at various levels of MP theory and comparing with experiment.
TL;DR: In this article, the contracted Gaussian basis sets for molecular calculations are derived from uncontracted (12,8) and ( 12,9) sets for the neutral second row atoms, Z=11-18, and for the negative ions P−, S−, and Cl−.
Abstract: Contracted Gaussian basis sets for molecular calculations are derived from uncontracted (12,8) and (12,9) sets for the neutral second row atoms, Z=11–18, and for the negative ions P−, S−, and Cl−. Calculations on Na...2p63p, 2P and Mg...2p63s3p, 3P are used to derive contracted Gaussian functions to describe the 3p orbital in these atoms, necessary in molecular applications. The derived basis sets range from minimal, through double‐zeta, to the largest set which has a triple‐zeta basis for the 3p orbital, double‐zeta for the remaining. Where necessary to avoid unacceptable energy losses in atomic wave functions expanded in the contracted Gaussians, a given uncontracted Gaussian function is used in two contracted functions. These tabulations provide a hierarchy of basis sets to be used in designing a convergent sequence of molecular computations, and to establish the reliability of the molecular properties under study.
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