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, H-1 NMR, C-13 NMR, mass spectra and elemental analysis. The theoretical calculations on 5 were carried out at the M06-2X and B3LYP methods with a 6-311++G(2d,p) basis set. The structural parameters and the IR data of 5 were analyzed and compared with the corresponding experimental data. The results show fair correlation between the calculated C-13 chemical shifts with B3LYP/6-311++G(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.