13C and 15N nuclear magnetic resonance spectra of Meisenheimer complexes of 1,3,5-trinitrobenzene

Abstract

¹³ C and ¹⁵N n.m.r. spectra (at the natural abundance level of ¹⁵N) have been measured and interpreted for the Meisenheimer complexes (I)–(XII) of 1,3,5-trinitrobenzene (TNB) with anions of cyclopentanone, cyclohexanone, cycloheptanone, acetone, dimethyl malonate, methyl cyanoacetate, methyl acetoacetate, pentane-2,4-dione, 3-methylpentane-2,4-dione, phenol, and methanol. ¹³C N.m.r. spectra of the corresponding carbon-acids have been measured in [²H₆]DMSO. The complexes derived from ketones and esters are present in the keto-form, that of (IX) exists in the enol form. Nitrogen atoms of nitro-groups at the 2- and 6-positions of complexes derived from carbon-acids of the type CH₂XY are anisochronous as also are C(2) and C(6), C(3) and C(5), and H(3) and H(5).