The comparison of NMR tensors and NQR frequencies of hallucinogenic Harmine compound in the gas phase

Abstract

Density functional theory (DFT) methods were used to analyze the effect of molecular structure and ring currents on the NMR chemical shielding tensors and NQR frequencies of hallucinogenic Harmine in the gas phase. The interpretation of NBO data is represented that in Harmine structure, the lone pair participation of N9 in π-system electron clouds cause to development of aromaticity nature in pyrrole ring. However, N9 atom of pyrrole ring has more value of chemical shielding (σiso) than N2 atom of pyridine former. It can be deduced that by increasing lone pair electrons contribution of nitrogen atoms in ring resonance interactions and aromaticity development, the values of NMR chemical shielding around them increase while χ and qzz values of these nuclei decrease.