化学
吡啶
范德瓦尔斯力
从头算
离子键合
结晶学
离解(化学)
计算化学
物理化学
分子
离子
药物化学
有机化学
作者
Anna V. Pomogaeva,Anna S. Lisovenko,Alexey Y. Timoshkin
摘要
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 I2 ) 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 [IPy2 ]+ cation with I3- or ICl2- counterions are more stable. Oligomerization favors ionic isomers starting from the tetrameric clusters of the composition (IX)4 Py4 .
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