Weakly bound complexes of 1,2,3-triazole with nitrogen and carbon dioxide isolated in solid argon: A combined FT-IR matrix isolation and theoretical investigation

Abstract

Matrix isolation FT-IR spectroscopy was combined with quantum-chemical calculations in order to characterize complexes of 1,2,3-triazole (3TR) with nitrogen and carbon dioxide. Geometries of the possible 1:1 and 1:2 complexes, as well as 3TR dimers, were optimized at the DFT (B3LYP-D3) level of theory with the 6-311++G(3df,3pd) basis set. Six different 3TR⋯N₂ structures of the 1:1 stoichiometry were optimized which are characterized by weak hydrogen bonds (N-H⋯N and C-H⋯N) and/or Van der Waals type interactions (N⋯C, N⋯N, N⋯π). Two the most stable geometries, both containing a N-H⋯N bridge, were identified experimentally in solid argon. As for 3TR⋯CO₂ complexes, out of two minima located on the potential energy surface, only one with a strongly bent N-H⋯O hydrogen bond was detected in the matrix after deposition. In both cases, only annealing experiments at 32 K resulted in the formation of small amounts of 1:2 structures.

Keywords: Azole; DFT; Hydrogen bond; Low-temperature matrices; van der Waals interaction.