Linear free energy relationships of 13C NMR chemical shifts in 4-substituted phenyl-4,5-dihydrobenzo[f][1,4]oxazepin-3(2H)-ones(thiones)

• Published in: Journal of molecular structure 2013-12, Vol.1053, p.61-65
• Main Authors: Agirbas, Hikmet, Kemal, Berat
• Format: Article
• Language: English
• Subjects: 13C NMR; Benzoxazepines; Carbon; Correlation; Correlation analysis; Density functional theory; Direct and extended polarizations; energy; Free energy; GIAO-DFT calculations; Mathematical analysis; Molecular structure; Nuclear magnetic resonance; nuclear magnetic resonance spectroscopy
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2013.09.011

•13C NMR chemical shifts in 4-substituted phenyl-4,5-dihydrobenzo[f][1,4]oxazepin-3(2H)-ones(thiones) were correlated with Hammett type substituent constants.•SSP (single substituent parameter) and DSP (dual substituent parameter) were applied.•Polar and resonance substituent effects satisfactorily operate at benzoxazepine carbon atoms.•DFT calculations were performed to determine the preferred geometry of the molecules and to calculate the theoretical 13C NMR chemical shifts. Linear free energy relationships (LFER) were applied to the 13C NMR chemical shifts in 4-substituted phenyl-4,5-dihydrobenzo[f][1,4]oxazepin-3(2H)-ones(thiones). The correlation analysis for the substituent-induced chemical shifts (SCS) with inductive and resonance parameters (σ, F and R) were carried out by using SSP (single substituent parameter) and DSP (dual substituent parameter). The presented calculation accounts satisfactorily for the polar and resonance substituent effects operating at benzoxazepine carbon atoms. Negative ρ values were found for several correlations (reverse substituent effect). For a better understanding of the results, density functional theory (DFT) calculations were performed to determine the preferred geometry and to calculate the theoretical 13C NMR chemical shifts.