Structure and IR spectroscopic properties of complexes of 1,2,4-triazole and 3-amino-1,2,4-triazole with dinitrogen isolated in solid argon

Complexes of 1,2,4-triazole (TR) and 3-amino-1,2,4-triazole (AT) with N2 were studied computationally employing MP2 and B3LYPD3 methods and experimentally by FTIR matrix isolation technique. The results show that both triazoles interact specifically with dinitrogen in several different ways. For the 1:1 complexes of 1,2,4triazole five stable minima were located on the potential energy surface. The most stable of them comprises a weak hydrogen bond formed between the NH group of the ring and the lone pair of the nitrogen molecule. The second most stable structure is bound by the NMIDLINE HORIZONTAL ELLIPSIS7c bond formed between one of the N atoms of the N2 molecule and the triazole ring. Three other complexes are stabilized by the C-HMIDLINE HORIZONTAL ELLIPSISN and NMIDLINE HORIZONTAL ELLIPSISN van der Waals interactions. In the case of 3-amino-1,2,4-triazole, the two most stable dinitrogen complexes are analogous to those found for the 1,2,4-triazole and involve N-HMIDLINE HORIZONTAL ELLIPSISN and NMIDLINE HORIZONTAL ELLIPSIS7c bonds. In other structures amino or CH groups act as proton donors to the N2 molecule. The NMIDLINE HORIZONTAL ELLIPSISN van der Waals interactions are also present. The analysis of the infrared spectra of low temperature matrices containing TR or AT and dinitrogen indicates that in both systems mostly 1:1 hydrogen-bonded complexes with the NH group interacting with N2 are present in solid argon.

Automated summary

This article investigates the interaction between 1,2,4-triazole and 3-amino-1,2,4-triazole with dinitrogen through both computational and experimental methods. The study reveals that these compounds can interact with dinitrogen in various specific ways. The analysis of infrared spectra suggests that 1:1 hydrogen-bonded complexes between the compounds and dinitrogen are predominant in low-temperature solid argon matrices.