¹⁵N NMR study of tetrazoles

Abstract

Abstract A natural abundance 15 N NMR study was carried out on a series of 1‐ and 2‐mono‐ and 1,5‐ and 2,5‐disubstituted tetrazoles in different media. An erroneous assignment given in the literature for 2,5‐disubstituted tetrazoles was corrected using MNDO molecular orbital calculations and the analysis of changes in the 15 N chemical shifts on protonation. Earlier assignments for 1‐ and 2‐mono‐ and 1,5‐disubstituted tetrazoles were confirmed by the same means and by the use of 15 N,H couplings. Direct proof that N‐4 is the protonation site is presented, to our knowledge for the first time.