Synthesis, crystal structure, theoretical calculations, and corrosion study of thiazine[1,5]benzodiazepine

A derivative of 1,5-benzodiazepine, specifically 2-methyl-6-phenyl-2,3-dihydro-1H-[1,3]thiazino[3,2-a]-1,5benzodiazepin-1-one (TBD), was synthesized by a cyclization [3 + 3] reaction involving the 4-phenyl-1,3dihydro-2H-1,5-benzodiazepine-2-thione and methacryloylchloride. The structure of TBD was characterized through various spectroscopic methods, including FT-IR, 1H NMR, 13C NMR, and HRMS, also it was confirmed by X-ray analysis. The corrosion inhibitory effectiveness of TBD for mild steel (MS) in 1 M HCl acid was inspected by the exploitation of electrochemical impedance spectroscopy (EIS) and potentiodynamic techniques. Monte Carlo (MC) simulations were employed to study the adsorption behavior of TBD on the Fe (110) surface, providing insights into its inhibitory efficiency against MS corrosion. The simulations were also utilized to calculate the energy of adsorption of the inhibitor onto MS. A comprehensive theoretical investigation, employing density functional theory (DFT) at the B3LYP/6-311 G (d,p) level, was carried out to validate the experimental findings regarding the inhibition properties of the synthesized product and to elucidate the corrosion inhibition mechanism.