Structures and stability of I 2 and ICl complexes with pyridine: Ab initio and DFT study

• Published in: Journal of Computational Chemistry
• Main Authors: Pomogaeva, Anna V., Lisovenko, Anna S., Timoshkin, Alexey Y.
• Other Authors: Russian Science Foundation
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2024
• Subjects: Lone; IPY
• Online Access: http://dx.doi.org/10.1002/jcc.27300; https://onlinelibrary.wiley.com/doi/pdf/10.1002/jcc.27300

Abstract Theoretical investigation of thermodynamic stability and bonding features of possible isomers of the molecular and ionic complexes of pyridine with molecular iodine and iodine monochloride IX (X = I,Cl) is presented. M06‐2X DFT functional is found to provide bond distances and dissociation energies which are close to those obtained at high‐level ab initio CCSD(T)/aug‐cc‐pvtz//CCSD/aug‐cc‐pvtz benchmark computations for the most stable isomers, formed via donation of a lone pair of nitrogen atom of pyridine to the iodine atom. These isomers are by 23–33 kJ mol −1 (in case of I 2 ) and by 39–56 kJ mol −1 (in case of ICl) more stable than other molecular complexes. T‐shaped π‐σ* bonded isomers turn out to be energetically comparable with van der Waals bound compounds. Among the ionic isomers, structures featuring [IPy 2 ] + cation with I 3 − or ICl 2 − counterions are more stable. Oligomerization favors ionic isomers starting from the tetrameric clusters of the composition (IX) 4 Py 4 .