Topological features and electronic structure of 4-chloro-1H-pyrrolo[2,3-b]pyridine: experimental charge density analysis and DFT studies?

CrystEngComm Pub Date: 2011-11-18 DOI: 10.1039/C1CE05615H

Abstract

The experimental charge density distribution in 4-chloro-1H-pyrrolo[2,3-b]pyridine has been carried out using high resolution X-ray diffraction data collected at 100(2) K. Multipole refinement based on the Hansen–Coppens formalism coupled with an estimation of anisotropic displacement parameters (ADPs) of hydrogen atoms converged to R(F) = 0.0353 for 5700 reflections with I > 3σ(I) and sin θ/λ ≤ 1.08 ??1. The topology of the bonding scheme within the molecule as well as of the intermolecular N–H?N and C–H?Cl hydrogen bonds has been investigated. The covalent nature of N–C and C–C bonds in the pyrrolopyridine skeleton of the molecule has been established by (3, ?1) bond critical points associated with relatively large electron densities [2.07(2)–2.74(3) e ??3] and highly negative Laplacian values [?11.37(4) to ?19.20(10) e ??5]. The topological parameters corresponding to H?N and H?Cl critical points indicate a moderately strong intermolecular N–H?N hydrogen bond and a weak C–H?Cl closed-shell interaction. The electronic structure of the title compound has been calculated by density functional theory (DFT) at the BLYP level. A large HOMO–LUMO energy gap (3.59 eV; HOMO is the highest occupied molecular orbital and LUMO is the lowest unoccupied molecular orbital) implies a high kinetic stability of the title compound.

Graphical abstract: Topological features and electronic structure of 4-chloro-1H-pyrrolo[2,3-b]pyridine: experimental charge density analysis and DFT studies
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