title: Comparison of the substituent effects on the (13) C NMR with the (1) H NMR chemical shifts of CH=N in substituted benzylideneanilines.
abstract: Fifty-two samples of substituted benzylideneanilines XPhCH=NPhYs (XBAYs) were synthesized, and their NMR spectra were determined in this paper. Together with the NMR data of other 77 samples of XBAYs quoted from literatures, the (1) H NMR chemical shifts (δH (CH=N)) and (13) C NMR chemical shifts (δC (CH=N)) of the CH=N bridging group were investigated for total of 129 samples of XBAYs. The result shows that the δH (CH=N) and δC (CH=N) have no distinctive linear relationship, which is contrary to the theoretical thought that declared the δH (CH=N) values would increase as the δC (CH=N) values increase. With the in-depth analysis, we found that the effects of σF and σR of X/Y group on the δH (CH=N) and the δC (CH=N) are opposite; the effects of the substituent specific cross-interaction effect between X and Y (Δσ(2) ) on the δH (CH=N) and the δC (CH=N) are different; the contributions of parameters in the regression equations of the δH (CH=N) and the δC (CH=N) [Eqns and 7), respectively] also have an obvious difference.
authors.affiliation: School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, China.|School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Key Laboratory of Theoretical Organic Chemistry and Function Molecule (Hunan University of Science and Technology), Ministry of Education, Hunan Provincial University Key Laboratory of QSAR/QSPR, Xiangtan, 411201, China.
authors.forename: Linyan
authors.initials: L
authors.lastname: Wang
authors.affiliation: School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Key Laboratory of Theoretical Organic Chemistry and Function Molecule (Hunan University of Science and Technology), Ministry of Education, Hunan Provincial University Key Laboratory of QSAR/QSPR, Xiangtan, 411201, China.
authors.forename: Chaotun
authors.initials: C
authors.lastname: Cao
authors.affiliation: School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, China.|School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Key Laboratory of Theoretical Organic Chemistry and Function Molecule (Hunan University of Science and Technology), Ministry of Education, Hunan Provincial University Key Laboratory of QSAR/QSPR, Xiangtan, 411201, China.
authors.forename: Chenzhong
authors.initials: C
authors.lastname: Cao
keywords: 13C NMR chemical shifts; 1H NMR chemical shifts; benzylideneanilines; substituent effects; substituent specific cross-interaction