Dynamic H NMR studies around the heteroaryl-carbon (N[InlineMediaObject not available: see fulltext.]CH−N) and nitrogen-carbon (N[InlineMediaObject not available: see fulltext.]C=CH) single bonds in a particular enaminoester involving a phenanthridine along with theoretical calculations

For the first time, a series of separate dynamic effects are reported at different temperatures within a particular enaminoester 4 involving a phenanthridine namely dimethyl-2-(6-(2-methylindol-1-yl)phenanthridine-5(6H)-yl) maleate. These effects are attributed to restricted rotation around the two single bonds such as heteroaryl-carbon (N[InlineMediaObject not available: see fulltext.]CH-N) and nitrogen-carbon (N[InlineMediaObject not available: see fulltext.]C=CH). Rotational energy barriers (Δ G) for these interconversion processes are 44.88 and 44.63 ± 1 kJ mol, respectively, in rotational isomers. In addition, theoretical studies on the basis of rotational around the same bonds were investigated using an ab initio method at HF/6-31G(d,p) and B3LYP/6-31G(d,p) levels of theory. Theoretical activation parameters including Δ H, Δ G, Δ S, and kinetic parameters involving E were calculated in the presence of a solvent medium (CDCl) at experimental temperature. The results indicated that the HF/6-31G(d,p) level provides more accurate data in comparison with the B3LYP method with the same basis set [6-31G(d,p)] for compound 4 and they are in relative agreement with dynamic H NMR data. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]