Behavior of Halogen Bonds of the Y−X⋅⋅⋅π Type (X, Y=F, Cl, Br, I) in the Benzene π System, Elucidated by Using a Quantum Theory of Atoms in Molecules Dual-Functional Analysis

ChemPhysChem ◽  
2016 ◽  
Vol 17 (16) ◽  
pp. 2579-2589 ◽  
Author(s):  
Yuji Sugibayashi ◽  
Satoko Hayashi ◽  
Waro Nakanishi
2020 ◽  
Vol 76 (2) ◽  
pp. 170-176 ◽  
Author(s):  
Kinga Wzgarda-Raj ◽  
Agnieszka J. Rybarczyk-Pirek ◽  
Sławomir Wojtulewski ◽  
Marcin Palusiak

Cocrystals of thiourea with 4-nitropyridine N-oxide, C5H4N2O3·2CH4N2S, (I), and 3-bromopyridine N-oxide, C5H4BrNO·CH4N2S, (II), crystallize in the monoclinic space group P21/c. In the crystals, molecules of both components are linked by N—H...O hydrogen bonds, creating R 2 1(6) synthons. The bromine substituent of the N-oxide component in (II) is a centre for C—Br...S halogen bonding to the thiourea molecule. Computations based on quantum chemistry methods (quantum theory of atoms in molecules, QTAIM) and atoms in molecules (AIM) theory were performed for a more detailed description of the observed type of halogen-bonding interaction.


2006 ◽  
Vol 84 (5) ◽  
pp. 771-781 ◽  
Author(s):  
Cina Foroutan-Nejad ◽  
Gholam Hossein Shafiee ◽  
Abdolreza Sadjadi ◽  
Shant Shahbazian

In this study, a detailed topological charge density analysis based on the quantum theory of atoms in molecules (QTAIM) developed by Bader and co-workers, has been accomplished (using the B3LYP method) on the CB62– anion and three planar isomers of the C3B4 species, which had been first proposed by Exner and Schleyer as examples of molecules containing hexacoordinate carbon atoms. The analysis uncovers the strong (covalent) interactions of boron atoms as well as the "nondirectional" interaction of central carbon atom with those peripheral atoms. On the other hand, instabilities have been found in the topological networks of (B6C)2– and B4C3(para) species. A detailed investigation of these instabilities demonstrates that the topology of charge density has a floppy nature near the equilibrium geometries of the species under study. Thus, these species seems to be best described as complexes of a relatively concrete ring containing boron or carbon atoms and a central carbon atom that is confined in the plane of the molecule, but with nondirectional interactions with the surrounding atoms.Key words: hypervalency, hexacoordinate carbon, quantum theory of atoms in molecules, charge density analysis, ab initio methods.


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