Spectroscopic, Crystal Structure, Hirshfeld Surface and DFT Studies of 2-Amino-4-Chlorobenzonitrile

Abstract

This research concentrates on a summary of the global reactivity parameters on the single crystal structure of 2-amino-4-chlorobenzonitrile, which can be utilised in a wide range of applications. The commercial 2-amino-4-chlorobenzonitrile in light yellow (Sigma-Aldrich) [ACBN] was recrystallized from ethanol. The compound crystallizes in the triclinic, P-1 space group with unit cell parameters a =3.8924 (9) Å, b = 6.7886 (15) Å, c = 13.838 (3) Å, α =77.559 (16)°, β = 8.898 (17)° and γ = 83.021 (17)°. The presence of intermolecular interactions was further analyzed via the Hirshfeld Surface analysis. The electronic properties of the compound were investigated via the Density Functional Theory (DFT) using the CIF file of the single crystal. Full geometry optimization was carried out using the DFT at B3LYP with 6-311++G (d, p) basis set level. The structure of the recrystallized ACBN was confirmed via single crystal X-ray Crystallography, FTIR, and UV-Vis. The IR spectrum showed three main stretching bands namely nitrile, C≡N (2211 cm-1), C-Cl (782 cm-1), and 1° NH (3452 and 3363 cm-1). The UV-Vis analysis showed two main absorption peaks namely π → π∗ and n → π∗ which occured in an aromatic ring and nitrile, C≡N. The compound crystallized in the triclinic system with the space group Pī. Nitrile (C≡N) and C-N have bond lengths of 1.146(4) and 1.369(4) Ǻ, which are less than the theoretical values of 1.160 and 1.470 Ǻ due to the conjugation of the aromatic ring. The intrinsic molecular characteristics analysis showed that the compound has the capability to donate electrons although it is categorized as a hard compound. The exploration of intrinsic molecular features revealed that, despite the fact that ACBN is stable and less reactive, it still has the ability to transfer and accept electrons. Furthermore, the Mulliken analysis revealed that the compound has the capability to function as a nucleophilic agent due to the nitrogen atoms (highly negative charges). As recommendation, the DFT study revealed that the compound can be investigated more thoroughly in terms of reaction kinetics and mechanisms such as corrosion inhibition and biological activities. © 2024, Malaysian Society of Analytical Sciences. All rights reserved.