scholarly journals Molecular Hydrogen as a Lewis Base in Hydrogen Bonds and Other Interactions

Molecules ◽  
2020 ◽  
Vol 25 (14) ◽  
pp. 3294 ◽  
Author(s):  
Sławomir J. Grabowski
Keyword(s):  
Hydrogen Bonds ◽  
Molecular Hydrogen ◽  
Spectroscopic Properties ◽  
Lewis Base ◽  
Basis Set ◽  
Orbital Method ◽  
Topological Parameters ◽  
Theoretical Approaches ◽  
Strength Of Interaction ◽  
Moller Plesset

The second-order Møller–Plesset perturbation theory calculations with the aug-cc-pVTZ basis set were performed for complexes of molecular hydrogen. These complexes are connected by various types of interactions, the hydrogen bonds and halogen bonds are most often represented in the sample of species analysed; most interactions can be classified as σ-hole and π-hole bonds. Different theoretical approaches were applied to describe these interactions: Quantum Theory of ‘Atoms in Molecules’, Natural Bond Orbital method, or the decomposition of the energy of interaction. The energetic, geometrical, and topological parameters are analysed and spectroscopic properties are discussed. The stretching frequency of the H-H bond of molecular hydrogen involved in intermolecular interactions is considered as a parameter expressing the strength of interaction.

scholarly journals The Nature of Triel Bonds, a Case of B and Al Centres Bonded with Electron Rich Sites

Molecules ◽  
2020 ◽  
Vol 25 (11) ◽  
pp. 2703 ◽  
Author(s):  
Sławomir J. Grabowski
Keyword(s):  
Lewis Acids ◽  
Weak Interactions ◽  
Lewis Base ◽  
Basis Set ◽  
Strong Interactions ◽  
Orbital Method ◽  
Covalent Bonds ◽  
Moller Plesset ◽  
Intermolecular Distances ◽  
Base Units

The second-order Møller–Plesset perturbation theory calculations with the aug-cc-pVTZ basis set were performed on complexes of triel species: BCl3, BH3, AlCl3, and AlH3 acting as Lewis acids through the B or Al centre with Lewis base units: NCH, N2, NH3, and Cl− anion. These complexes are linked by triel bonds: B/Al⋅⋅⋅N or B/Al⋅⋅⋅Cl. The Quantum Theory of ´Atoms in Molecules´ approach, Natural Bond Orbital method, and the decomposition of energy of interaction were applied to characterise the latter links. The majority of complexes are connected through strong interactions possessing features of covalent bonds and characterised by short intermolecular distances, often below 2 Å. The BCl3⋅⋅⋅N2 complex is linked by a weak interaction corresponding to the B⋅⋅⋅N distance of ~3 Å. For the BCl3⋅⋅⋅NCH complex, two configurations corresponding to local energetic minima are observed, one characterised by a short B⋅⋅⋅N distance and a strong interaction and another one characterised by a longer B⋅⋅⋅N distance and a weak triel bond. The tetrahedral triel structure is observed for complexes linked by strong triel bonds, while, for complexes connected by weak interactions, the structure is close to the trigonal pyramid, particularly observed for the BCl3⋅⋅⋅N2 complex.

scholarly journals Hydrogen and Lithium Bonds—Lewis Acid Units Possessing Multi-Center Covalent Bonds

Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 6939
Author(s):  
Mohammad Aarabi ◽  
Samira Gholami ◽  
Sławomir J. Grabowski
Keyword(s):  
Perturbation Theory ◽  
Quantum Theory ◽  
Lewis Acid ◽  
Molecular Hydrogen ◽  
Lewis Base ◽  
Lithium Cation ◽  
Electron Systems ◽  
Covalent Bonds ◽  
Covalent Interaction ◽  
Theoretical Approaches

MP2/aug-cc-pVTZ calculations were carried out on complexes wherein the proton or the lithium cation is located between π-electron systems, or between π-electron and σ-electron units. The acetylene or its fluorine and lithium derivatives act as the Lewis base π-electron species similarly to molecular hydrogen, which acts as the electron donor via its σ-electrons. These complexes may be classified as linked by π-H∙∙∙π/σ hydrogen bonds and π-Li∙∙∙π/σ lithium bonds. The properties of these interactions are discussed, and particularly the Lewis acid units are analyzed, because multi-center π-H or π-Li covalent bonds may occur in these systems. Various theoretical approaches were applied here to analyze the above-mentioned interactions—the Quantum Theory of Atoms in Molecules (QTAIM), the Symmetry-Adapted Perturbation Theory (SAPT) and the Non-Covalent Interaction (NCI) method.

scholarly journals Hydrogen Bonds with BF4− Anion as a Proton Acceptor

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 460 ◽  
Author(s):  
Sławomir J. Grabowski
Keyword(s):  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Intermolecular Interactions ◽  
Lewis Base ◽  
Cambridge Structural Database ◽  
Proton Acceptor ◽  
Strength Of Interaction ◽  
Structural Database ◽  
Short Contacts ◽  
Base Properties

The BF4− anion is characterised by weak Lewis base properties; it is usually classified as a “non-coordinating anion”. The searches through the Cambridge Structural Database (CSD) were performed and it was found that the BF4− anion often occurs in crystal structures and it is involved in numerous intermolecular interactions; hydrogen bonds are the majority of them. The hydrogen bonds involving the BF4− anion as a proton acceptor are closer to linearity with the increase of the strength of interaction that is in line with the tendency known for other hydrogen bonds. However, even for short contacts between the proton and the Lewis base centre, slight deviations from linearity occur. The MP2/aug-cc-pVTZ calculations on the BF4−…HCN complex and on the BF4−…(HCN)4 cluster were also carried out to characterise corresponding C-H…F hydrogen bonds; such interactions often occur in crystal structures.

Ab initio calculations on C6H6···(HF)n clusters — X–H···π hydrogen bond

2010 ◽  
Vol 88 (8) ◽  
pp. 769-778 ◽  
Author(s):  
Sławomir J. Grabowski ◽  
Jesus M. Ugalde
Keyword(s):  
Hydrogen Bond ◽  
Quantum Theory ◽  
Hydrogen Bonds ◽  
Linear Chain ◽  
Benzene Molecule ◽  
Lewis Base ◽  
Topological Parameters ◽  
Linear Complexes ◽  
Cooperativity Effects ◽  
Ring Critical Point

MP2/6–311++G(d,p) calculations on C6H6···(HF)n clusters were performed and full optimizations were carried out for systems containing up to four HF molecules (n = 4) and calculations on the systems of C6v symmetry were carried out for up to six HF molecules (n = 6). Cooperativity effects were analyzed for these molecular aggregates. It was found that F–H···π and F–H···F hydrogen bonds exist for these complexes and those interactions are enhanced as the number of HF molecules increases. The cooperativity effects cause numerous changes in geometrical, energetic, and topological parameters, the latter ones derived from the quantum theory of atoms in molecules. Various correlations between the analyzed parameters are presented. There are meaningful differences between the molecular graphs for the fully optimized complexes and those for the linear complexes of C6v symmetry (for the latter, the linear chain of HF molecules is attached to a benzene molecule acting as the Lewis base). For the linear complexes, unique bond paths connect the H-attractor of the HF molecule and the ring critical point of the benzene molecule.

scholarly journals Cooperation/Competition between Halogen Bonds and Hydrogen Bonds in Complexes of 2,6-Diaminopyridines and X-CY3 (X = Cl, Br; Y = H, F)

Symmetry ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 766
Author(s):  
Barbara Bankiewicz ◽  
Marcin Palusiak
Keyword(s):  
Complex Formation ◽  
Hydrogen Bonds ◽  
Dft Calculations ◽  
Electrostatic Interactions ◽  
Dipole Moments ◽  
Main Role ◽  
Halogen Bonds ◽  
Topological Parameters ◽  
Leading Role ◽  
The Impact

The DFT calculations have been performed on a series of two-element complexes formed by substituted 2,6-diaminopyridine (R−PDA) and pyridine (R−Pyr) with X−CY3 molecules (where X = Cl, Br and Y = H, F). The primary aim of this study was to examine the intermolecular hydrogen and halogen bonds in the condition of their mutual coexistence. Symmetry/antisymmetry of the interrelation between three individual interactions is addressed. It appears that halogen bonds play the main role in the stabilization of the structures of the selected systems. However, the occurrence of one or two hydrogen bonds was associated with the favourable geometry of the complexes. Moreover, the impact of different substituent groups attached in the para position to the aromatic ring of the 2,6-diaminopyridine and pyridine on the character of the intermolecular hydrogen and halogen bonds was examined. The results indicate that the presence of electron-donating substituents strengthens the bonds. In turn, the presence of electron-withdrawing substituents reduces the strength of halogen bonds. Additionally, when hydrogen and halogen bonds lose their leading role in the complex formation, the nonspecific electrostatic interactions between dipole moments take their place. Analysis was based on geometric, energetic, and topological parameters of the studied systems.

Systhesis, Characterization and Spectroscopic Properties of (2E,6E)-2,6-Bis(2,3,4-tri-methoxy-benzylidene)cyclohexanone

2011 ◽  
Vol 396-398 ◽  
pp. 2338-2341
Author(s):  
Xing Chuan Wei ◽  
Zhi Li Liu ◽  
Kun Zhang ◽  
Zhi Yun Du ◽  
Xi Zheng
Keyword(s):  
Crystal Structure ◽  
Acetic Acid ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Spectroscopic Properties ◽  
Spectral Studies ◽  
Double Bonds ◽  
X Ray ◽  
Π Interactions ◽  
X Ray Crystallography

In this paper, (2E,6E)-2,6-Bis(2,3,4-tri-methoxy -benzylidene)cyclohexanone (omitted as tmbcho) (1) was obtained by the reaction of acetic acid, tetrahydrofuran, cyclohexanone and 2,3,4-tri-methoxy-benzaldehyde. Three non-classic hydrogen bonds were observed in the compound. X-ray crystallography shows that the crystal structure is stabilized by intermolecular C-H•••π interactions and it contains plenty of conjugated double bonds. The title compound was characterized by UV-vis and fluorescent spectral studies.

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