Cl···Cl interactions in molecular crystals: insights from the theoretical charge density analysis.
The structure, IR harmonic frequencies and intensities of normal vibrations of 20 molecular crystals with the X-Cl···Cl-X contacts of different types, where X = C, Cl, and F and the Cl···Cl distance varying from ~3.0 to ~4.0 Å, are computed using the solid-state DFT method. The obtained crystalline wave functions have been further used to define and describe quantitatively the Cl···Cl interactions via the electron-density features at the Cl···Cl bond critical points. We found that the electron-density at the bond critical point is almost independent of the particular type of the contact or hybridization of the ipso carbon atom. The energy of Cl···Cl interactions, E(int), is evaluated from the linking E(int) and local electronic kinetic energy density at the Cl···Cl bond critical points. E(int) varies from 2 to 12 kJ/mol. The applicability of the geometrical criterion for the detection of the Cl···Cl interactions in crystals with two or more intermolecular Cl···Cl contacts for the unique chlorine atom is not straightforward. The detection of these interactions in such crystals may be done by the quantum-topological analysis of the periodic electron density.
Department of Quantum Chemistry, Mendeleev University of Chemical Technology, Miusskaya Square 9, 125047 Moscow, Russia. mikhail.vener@gmail.com
Mikhail V
MV
Vener
Anastasia V
AV
Shishkina
Alexey A
AA
Rykounov
Vladimir G
VG
Tsirelson
D015101:3,3'-Dichlorobenzidine / Q000737:chemistry; D002713:Chlorine / Q000737:chemistry*; D003198:Computer Simulation; D008968:Molecular Conformation; D013816:Thermodynamics
D015101:3,3'-Dichlorobenzidine; D002713:Chlorine