Perhalomethyl Chromones: Spectroscopic, X-Ray Diffraction, Hirshfeld Surface, and Density Functional Theory Studies of the Noncovalent Interactions

Abstract

The structure of two perhalomethylated chromones, 2-chlorodifluoromethylchromone (a) and its 6-nitro substituted derivative (b), are investigated. The supramolecular assembly is governed by the hydrogen bond interaction (C−H···O) between the olefinic proton (OC−C(=C<)-H) and the carbonyl oxygen atom (>C=O) giving rise to center-symmetric (Formula presented.) graph-set motifs. The H···O interatomic distance is shorter in (b) suggesting a stronger hydrogen bonding for this derivative. Quantum Theory of Atoms in Molecules (QTAIM) and natural bond orbital (NBO) calculated energies and the higher polarity computed for (b) agree with this experimental finding. The Molecular Electrostatic Potential (MEP) graph shows a distinctive C···Cl contact, found only for (b), involving a more electrophilic methine carbon atom.