Probing the Intermolecular Interactions in [C2H5OH⋯CCl4] Complex Using Matrix Isolation Infrared Spectroscopy and Anharmonic Vibrational Analysis

ABSTRACT Understanding intermolecular interactions between halomethanes and alcohols is essential for elucidating their roles in atmospheric processes, solvent mixture behavior, and biochemical toxicity. Herein, a 1:1 complex of ethanol with carbon‐tetrachloride has been investigated using matrix isolation infrared spectroscopy supported by high‐level electronic structure calculations and anharmonic vibrational analysis. The molecule exists in two different conformers, that is, anti ‐ (A‐) and gauche ‐ (G‐) and both conformers can bind to . Electronic structure calculations have been performed to identify the possible binding motifs between and . Two minima have been obtained on the dimer potential energy surface stabilized by C─Cl O halogen bond and O─H Cl hydrogen bond. Experiments have been carried out in a low‐temperature Ar matrix using Fourier transform infrared spectroscopy. Natural bond orbital (NBO) analysis, Energy decomposition analysis (EDA), and quantum theory of atoms in molecules (QTAIM) have also been explored to investigate the nature of non‐covalent interactions. Reduced‐ and full‐dimensional VPT2 calculations demonstrate that accurate modeling of experimental frequencies requires explicit inclusion of low‐frequency intermolecular modes. The combined spectroscopic and computational studies establish that halogen bonding governs complex formation under matrix‐isolation conditions and highlight the importance of selective anharmonic coupling in predicting vibrational signatures of weakly bound complexes.