Spectroscopic investigations of the new anhydrous proton‐conducting compound of pyrazole with oxalate acid

Abstract

AbstractDicarboxylic acid salts are a good group of compounds in which one can study a variety of supramolecular structures as dimers, catemer chains, and rings and are interesting for crystal engineering of proton conductors for applications in solid‐state hydrogen fuel cells. The optical properties of the new proton‐conducting compound of pyrazole with oxalate acid were investigated using Raman and IR spectroscopy taking into account the formal classification of the fundamental modes. To gain more information on the intermolecular interactions and molecular vibrations, experimental data obtained for 1H‐pyrazol‐2‐ium hydrogen oxalate salt were supported by the quantum‐chemical calculations (density functional theory), Hirshfield surfaces and fingerprint plots analysis, and Bader theory calculations. Topological properties of the planar oxalic acid dimer and oxalic acid pyrazole tetramer have been calculated within the quantum theory of atoms in molecules, and it was shown that dominant types of interactions in the investigated salt are medium strength hydrogen‐bonding interactions.