Experimental and GIAO 15N NMR study of substituent effects in 1H-tetrazoles.

ARIDOSS, G.; ZHAO, C.; BOROSKY, GABRIELA L.; LAALI, KENNETH K.

JOURNAL OF ORGANIC CHEMISTRY

AMER CHEMICAL SOC

Año: 2012 p. 4152 - 4155

0022-3263

A series of 1-aryl/alkyl-1H-1,2,3,4-tetrazoles, 5-substituted 1H-tetrazoles, and 1,5- and 2,5-disubstituted 1Htetrazoles were studied by a combination of experimental NMR (natural abundance 15N, 15N/1H HMBC, and 13C) and computational GIAO-NMR techniques to explore substituent effects on 15N (and 13C) NMR chemical shifts in the tetrazole (TA) moiety. Computed 15N chemical shifts via GIAO-B3LYP/6-311+G(2d,p) calculations gave satisfactory results in comparison with experimental data. Whereas N-alkylation leads to large 15N chemical shift changes, changes in the N1-aryl derivatives bearing diverse substituent(s) are generally small except for polar ortho-substituents (COOH, NO2). Large Ää15N values were computed in N1-aryl derivatives for p-COH2+ and p-OMeH+ as extreme examples of electron-withdrawing substituents on a TA moiety.H-1,2,3,4-tetrazoles, 5-substituted 1H-tetrazoles, and 1,5- and 2,5-disubstituted 1Htetrazoles were studied by a combination of experimental NMR (natural abundance 15N, 15N/1H HMBC, and 13C) and computational GIAO-NMR techniques to explore substituent effects on 15N (and 13C) NMR chemical shifts in the tetrazole (TA) moiety. Computed 15N chemical shifts via GIAO-B3LYP/6-311+G(2d,p) calculations gave satisfactory results in comparison with experimental data. Whereas N-alkylation leads to large 15N chemical shift changes, changes in the N1-aryl derivatives bearing diverse substituent(s) are generally small except for polar ortho-substituents (COOH, NO2). Large Ää15N values were computed in N1-aryl derivatives for p-COH2+ and p-OMeH+ as extreme examples of electron-withdrawing substituents on a TA moiety.