Spectral and quantum chemical analysis of ethyl 4-[3-(adamantan-1-yl)-4-phenyl-5-sulfanylidene-4,5-dihydro-1H-1,2,4-triazole-1-yl]methylpiperazine-1-carboxylate

The Fourier transform infrared and Raman spectra of the adamantane-based compound ethyl 4-[3-(adamantan-1-yl)-4-phenyl-5-sulfanylidene-4,5-dihydro-1H-1,2,4-triazol-1-yl]methylpiperazine-1-carboxylate were recorded in the ranges of 3200–650[Formula: see text]cm[Formula: see text] and 3200–150[Formula: see text]cm[Formula: see text], respectively. The UV/Vis spectrum of solution of the title compound in ethanol was measured in the range of 450–200[Formula: see text]nm. The DFT calculations at the B3LYP/cc-pVDZ and B3LYP/cc-pVTZ levels of the theory were performed to obtain the equilibrium geometric structure and to predict vibrational IR and Raman spectra of the title molecule. The TDDFT calculations at the CAM-B3LYP/cc-pVTZ level of the theory, as well as MRPT calculations at the CASSCF(4,5)/XMCQDPT2 level of the theory were carried out to reproduce the electronic absorption spectrum. The experimental IR, Raman and UV/Vis spectra were interpreted on the basis of results of quantum chemical modeling. Based on Mulliken and Löwdin atomic population analysis, it was established that the compound under study exhibits features of an intramolecular charge transfer.