Reactivity of pyrazole derivatives with halomethanes: A DFT theoretical study

Abstract

The N-alkylation reaction of pyrazole derivatives with halomethanes was studied using density functional theory (DFT). The hybrid method B3LYP was employed, along with an ECP basis set such as LANL2DZ for halogen atoms (X = Cl, Br, I) and the 6-311 + G(d,p) basis set for all other atoms. In order to predict the specific site at which the pyrazole derivatives interact with halomethanes, local reactivity descriptors such as the Fukui functions were calculated. Detailed analysis of transition-state energies showed that alkylation occurred at the nitrogen atom N in the pyrazole derivatives, in agreement with the chemical reactivity results. The reaction mechanisms were elucidated by performing intrinsic reaction coordinate (IRC) calculations that considered the effects of the solvent and the species of halogen in the halomethane.

Halocarbon Encapsulation via Halogen···π Interactions in a Bispyrazole-Based Cryptand

“…Also, CH 2 Cl 2 is the most inactive molecule for halogen bonding capability and mostly form hydrogen bonds as described by Ivanov et al 23 For such inactive halomethanes to form a halogen bond, electron-rich molecules are required. Theoretical studies of pyrazole molecules have been carried out 22 where electrostatic surface potential (ESP) distribution of pyrazole molecules showed that most negative potential occurs at the N atom, which may add significant contribution for inactive haloalkanes to form halogen bonding interactions.…”

Regioselective Direct C−H Bond (Hetero)arylation of Thiazoles Enabled by a Novel Iminopyridine-Based α‐Diimine Nickel(II) Complex Evaluated by DFT Studies.

“…Geometry optimizations were performed at the PBE0-D3(BJ)/def2-SVP level 56-57-58 . Transition state structures were obtained using the intrinsic reaction coordinate [59][60] (IRC) method. Frequency calculations were performed on all stationary points, no imaginary frequencies were observed for the minima, and a single imaginary frequency corresponding to the reaction coordinate was found for all transition states (TSs).…”

Structural study, vibrational and optical properties, Hirshfeld surface analysis and DFT investigation of a novel organic cation hexachloridostannate(IV), (C5H8N3)2[SnCl6]

“…The molecular electrostatic potential (MEP) has been used as a qualitative tool for identifying molecular regions susceptible to electrophilic or nucleophilic attack, and for analyzing and predicting noncovalent interactions [70][71][72][73]. The electrostatic potential maps are color-coded and are subdivided into many regions where those various colors are used to identify different potentials.…”