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Journal ArticleDOI: 10.1039/D0CP06547A

Anion-anion and anion-neutral triel bonds.

04 Mar 2021-Physical Chemistry Chemical Physics (The Royal Society of Chemistry)-Vol. 23, Iss: 8, pp 4818-4828
Abstract: The ability of a TrCl4− anion (Tr = Al, Ga, In, Tl) to engage in a triel bond with both a neutral NH3 and CN− anion is assessed by ab initio quantum calculations in both the gas phase and in aqueous medium. Despite the absence of a positive σ or π-hole on the Lewis acid, strong triel bonds can be formed with either base. The complexation involves an internal restructuring of the tetrahedral TrCl4− monomer into a trigonal bipyramid shape, where the base can occupy either an axial or equatorial position. Although this rearrangement requires a substantial investment of energy, it aids the complexation by imparting a much more positive MEP to the site that is to be occupied by the base. Complexation with the neutral base is exothermic in the gas phase and even more so in water where interaction energies can exceed 30 kcal mol−1. Despite the long-range coulombic repulsion between any pair of anions, CN− can also engage in a strong triel bond with TrCl4−. In the gas phase, complexation is endothermic, but dissociation of the metastable dimer is obstructed by an energy barrier. The situation is entirely different in solution, with large negative interaction energies of as much as −50 kcal mol−1. The complexation remains an exothermic process even after the large monomer deformation energy is factored in.

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Topics: Lewis acids and bases (50%)

10 results found

Open accessJournal ArticleDOI: 10.1002/ANIE.202104592
Andrea Daolio1, Andrea Pizzi1, Giancarlo Terraneo1, Maurizio Ursini1  +2 moreInstitutions (1)
21 Jun 2021-Angewandte Chemie
Abstract: Interactions in crystalline tetrachloridoaurates of acetylcholine and dimethylpropiothetine are characterized by Au⋅⋅⋅Cl and Au⋅⋅⋅O short contacts. The former interactions assemble the AuCl4- units into supramolecular anionic polymers, while the latter interactions append the acetylcholine and propiothetine units to the polymer. The distorted octahedral geometry of the bonding pattern around the gold center is rationalized on the basis of the anisotropic distribution of the electron density, which enables gold to behave as an electrophile (π-hole coinage-bond donor). Computational studies prove that gold atoms in negatively charged species can function as acceptors of electron density. The attractive nature of the Au⋅⋅⋅Cl/O interactions described here complement the known aurophilic bonds involved in gold-centered interactions.

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11 Citations

Open accessJournal ArticleDOI: 10.3390/MOLECULES26082116
07 Apr 2021-Molecules
Abstract: Ab initio calculations are applied to the question as to whether a AeX5− anion (Ae = Kr, Xe) can engage in a stable complex with another anion: F−, Cl−, or CN−. The latter approaches the central Ae atom from above the molecular plane, along its C5 axis. While the electrostatic repulsion between the two anions prevents their association in the gas phase, immersion of the system in a polar medium allows dimerization to proceed. The aerogen bond is a weak one, with binding energies less than 2 kcal/mol, even in highly polar aqueous solvent. The complexes are metastable in the less polar solvents THF and DMF, with dissociation opposed by a small energy barrier.

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Topics: Dissociation (chemistry) (51%)

4 Citations

Journal ArticleDOI: 10.1039/D1CP01502H
Abstract: The possibility that MX3− anions can interact with one another is assessed via ab initio calculations in gas phase as well as in aqueous and ethanol solution. A pair of such anions can engage in two different dimer types. In the bridged configuration, two X atoms engage with two M atoms in a rhomboid structure with four equal M–X bond lengths. The two monomers retain their identity in the stacked geometry which contains a pair of noncovalent M⋯X interactions. The relative stabilities of these two structures depend on the nature of the central M atom, the halogen substituent, and the presence of solvent. The interaction and binding energies are fairly small, generally no more than 10 kcal mol−1. The large electrostatic repulsion is balanced by a strong attractive polarization energy.

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Topics: Bond length (54%), Dimer (51%), Ab initio quantum chemistry methods (50%)

3 Citations

Journal ArticleDOI: 10.1002/CPHC.202100332
Qingqing Yang1, Qingzhong Li1, Steve Scheiner2Institutions (2)
16 Jul 2021-ChemPhysChem
Abstract: The ability of B atoms on two different molecules to engage with one another in a noncovalent diboron bond is studied by ab initio calculations. Due to electron donation from its substituents, the trivalent B atom of BYZ2 (Z=CO, N2 , and CNH; Y=H and F) has the ability to in turn donate charge to the B of a BX3 molecule (X=H, F, and CH3 ), thus forming a B⋅⋅⋅B diboron bond. These bonds are of two different strengths and character. BH(CO)2 and BH(CNH)2 , and their fluorosubstituted analogues BF(CO)2 and BF(CNH)2 , engage in a typical noncovalent bond with B(CH3 )3 and BF3 , with interaction energies in the 3-8 kcal/mol range. Certain other combinations result in a much stronger diboron bond, in the 26-44 kcal/mol range, and with a high degree of covalent character. Bonds of this type occur when BH3 is added to BH(CO)2 , BH(CNH)2 , BH(N2 )2 , and BF(CO)2 , or in the complexes of BH(N2 )2 with B(CH3 )3 and BF3 . The weaker noncovalent bonds are held together by roughly equal electrostatic and dispersion components, complemented by smaller polarization energy, while polarization is primarily responsible for the stronger ones.

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Topics: Covalent bond (53%), Atoms in molecules (51%), Non-covalent interactions (50%) ... show more

2 Citations

Open accessJournal ArticleDOI: 10.1002/CPHC.202100681
28 Sep 2021-ChemPhysChem
Abstract: In this communication experimental and theoretical results are reported affording strong evidence that interactions between electron rich atoms and the metal of tetroxide anions of group 7 elements are a new case of attractive and σ-hole interactions. Single crystal X-ray analyses, molecular electrostatic potentials, quantum theory of atoms-in-molecules, and noncovalent interaction plot analyses show that in crystalline permanganate and perrhenate salts the metal in Mn/ReO4- anion can act as electron acceptors, the oxygen of another Mn/ReO4- anion can act as the donor and supramolecular anionic dimers or polymers are formed. The name matere bond (MaB) is proposed to categorize these noncovalent interactions and to differentiate them from the classical metal-ligand coordination bond.

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Topics: Perrhenate (66%), Non-covalent interactions (57%), Supramolecular chemistry (55%) ... show more

2 Citations


88 results found

Journal ArticleDOI: 10.1016/0263-7855(96)00018-5
Abstract: VMD is a molecular graphics program designed for the display and analysis of molecular assemblies, in particular biopolymers such as proteins and nucleic acids. VMD can simultaneously display any number of structures using a wide variety of rendering styles and coloring methods. Molecules are displayed as one or more "representations," in which each representation embodies a particular rendering method and coloring scheme for a selected subset of atoms. The atoms displayed in each representation are chosen using an extensive atom selection syntax, which includes Boolean operators and regular expressions. VMD provides a complete graphical user interface for program control, as well as a text interface using the Tcl embeddable parser to allow for complex scripts with variable substitution, control loops, and function calls. Full session logging is supported, which produces a VMD command script for later playback. High-resolution raster images of displayed molecules may be produced by generating input scripts for use by a number of photorealistic image-rendering applications. VMD has also been expressly designed with the ability to animate molecular dynamics (MD) simulation trajectories, imported either from files or from a direct connection to a running MD simulation. VMD is the visualization component of MDScope, a set of tools for interactive problem solving in structural biology, which also includes the parallel MD program NAMD, and the MDCOMM software used to connect the visualization and simulation programs. VMD is written in C++, using an object-oriented design; the program, including source code and extensive documentation, is freely available via anonymous ftp and through the World Wide Web.

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Topics: Rendering (computer graphics) (52%), Molecular graphics (52%), Visualization (51%) ... show more

36,939 Citations

Journal ArticleDOI: 10.1063/1.456153
Abstract: In the past, basis sets for use in correlated molecular calculations have largely been taken from single configuration calculations. Recently, Almlof, Taylor, and co‐workers have found that basis sets of natural orbitals derived from correlated atomic calculations (ANOs) provide an excellent description of molecular correlation effects. We report here a careful study of correlation effects in the oxygen atom, establishing that compact sets of primitive Gaussian functions effectively and efficiently describe correlation effects i f the exponents of the functions are optimized in atomic correlated calculations, although the primitive (s p) functions for describing correlation effects can be taken from atomic Hartree–Fock calculations i f the appropriate primitive set is used. Test calculations on oxygen‐containing molecules indicate that these primitive basis sets describe molecular correlation effects as well as the ANO sets of Almlof and Taylor. Guided by the calculations on oxygen, basis sets for use in correlated atomic and molecular calculations were developed for all of the first row atoms from boron through neon and for hydrogen. As in the oxygen atom calculations, it was found that the incremental energy lowerings due to the addition of correlating functions fall into distinct groups. This leads to the concept of c o r r e l a t i o n c o n s i s t e n t b a s i s s e t s, i.e., sets which include all functions in a given group as well as all functions in any higher groups. Correlation consistent sets are given for all of the atoms considered. The most accurate sets determined in this way, [5s4p3d2f1g], consistently yield 99% of the correlation energy obtained with the corresponding ANO sets, even though the latter contains 50% more primitive functions and twice as many primitive polarization functions. It is estimated that this set yields 94%–97% of the total (HF+1+2) correlation energy for the atoms neon through boron.

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Topics: STO-nG basis sets (65%), Basis set (57%), Quantum chemistry composite methods (53%) ... show more

24,491 Citations

Journal ArticleDOI: 10.1080/00268977000101561
01 Oct 1970-Molecular Physics
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.

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18,088 Citations

Journal ArticleDOI: 10.1021/CR9904009
26 Jul 2005-Chemical Reviews
Abstract: 6.2.2. Definition of Effective Properties 3064 6.3. Response Properties to Magnetic Fields 3066 6.3.1. Nuclear Shielding 3066 6.3.2. Indirect Spin−Spin Coupling 3067 6.3.3. EPR Parameters 3068 6.4. Properties of Chiral Systems 3069 6.4.1. Electronic Circular Dichroism (ECD) 3069 6.4.2. Optical Rotation (OR) 3069 6.4.3. VCD and VROA 3070 7. Continuum and Discrete Models 3071 7.1. Continuum Methods within MD and MC Simulations 3072

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11,599 Citations

Open accessJournal ArticleDOI: 10.1103/PHYSREV.46.618
01 Oct 1934-Physical Review
Abstract: A perturbation theory is developed for treating a system of n electrons in which the Hartree-Fock solution appears as the zero-order approximation. It is shown by this development that the first order correction for the energy and the charge density of the system is zero. The expression for the second-order correction for the energy greatly simplifies because of the special property of the zero-order solution. It is pointed out that the development of the higher approximation involves only calculations based on a definite one-body problem.

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11,522 Citations

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