Unveiling the spectroscopy of 2-(nitromethylene)imidazolidine: From experimental findings to theoretical insights.

Imidazolidine compounds have a wide range of applications in various fields, ranging from pharmaceuticals to corrosion inhibition. Their structural flexibility enables the synthesis of numerous analogues through chemical substitution, establishing them as a valuable framework for experimental and theoretical studies. In this work, the molecular properties of 2-(nitromethylene) imidazolidine (IMD), a promising steel corrosion inhibitor, is investigated by combining experimental measurements with density functional theory (DFT) calculations. Electronic structure calculations were carried out to assist in the interpretation of experimentally obtained nuclear magnetic resonance (NMR) spectra, Raman spectrum and UV/VIS spectra. As main results, the absorption maximum of IMD was observed at 370 nm, corresponding to the S0→ S1 excitation. The experimental and theoretical Raman spectra obtained in the region of 100-1700 cm-1 showed good agreement, as well as the theoretical and experimental NMR spectra for 100 and 400 MHz. In addition, the spin-orbit coupling (SOC) calculation of 48.38 cm-1 reveal that the triplet sublevel with MS=+1 provides the dominant contribution to the phosphorescence mechanism in IMD.