Experimental and Theoretical Studies on a Derivative of Tetrahydro-1H-Benzodiazepine

N-Cyclohexyl-2,4,4-trimethyl-2,3,4,5-tetrahydro-1H-benzo[b][1,5]diazepine-2-carboxamide (5) was synthesized using an efficient, highly recyclable and eco-friendly catalyst heteropolyacid/triethoxysilyl)propyl]isonicotinamide (HPA/TPI-Fe3O4 nanoparticles) in one-pot. The compound 5 was characterized by FT-IR,1H NMR, 13C NMR, mass spectra, and elemental analysis. The theoretical calculations on 5 were carried out at the M062X and B3LYP methods with a 6-311(2d,p) basis set. The structural parameters and the IR data of 5 were analyzed and compared with the related experimental data. The results show fair correlation between the calculated 13C chemical shifts with B3LYP/6-311(2d,p) level and experimental data. Theoretical studies on the frontier molecular orbitals, mapped molecular electrostatic potential (MEP) and corresponding graphs and charge delocalization of 5 were also carried out.