title: Experimental and GIAO 15N NMR study of substituent effects in 1H-tetrazoles.
abstract: A series of 1-aryl/alkyl-1H-1,2,3,4-tetrazoles, 5-substituted 1H-tetrazoles, and 1,5- and 2,5-disubstituted 1H-tetrazoles were studied by a combination of experimental NMR (natural abundance (15)N, (15)N/(1)H HMBC, and (13)C) and computational GIAO-NMR techniques to explore substituent effects on (15)N (and (13)C) NMR chemical shifts in the tetrazole (TA) moiety. Computed (15)N 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 (15)N chemical shift changes, changes in the N(1)-aryl derivatives bearing diverse substituent(s) are generally small except for polar ortho-substituents (COOH, NO(2)). Large Δδ(15)N values were computed in N(1)-aryl derivatives for p-COH(2)(+) and p-OMeH(+) as extreme examples of electron-withdrawing substituents on a TA moiety.
authors.affiliation: Department of Chemistry, University of North Florida, 1 UNF Drive, Jacksonville, Florida 32224, USA.
authors.forename: Gopalakrishnan
authors.initials: G
authors.lastname: Aridoss
authors.forename: Chunqing
authors.initials: C
authors.lastname: Zhao
authors.forename: Gabriela L
authors.initials: GL
authors.lastname: Borosky
authors.forename: Kenneth K
authors.initials: KK
authors.lastname: Laali
mesh_terms: D002247:Carbon Isotopes / Q000737:chemistry*; D039301:Computers, Molecular; D004583:Electrons; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D015394:Molecular Structure; D013777:Tetrazoles / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: D002247:Carbon Isotopes; D013777:Tetrazoles; C045574:1H-tetrazole