NMR Study of isolobal N-CH3+, N-BH3 and N-BF3 imidazole derivatives

✍ Scribed by Itzia Irene Padilla-Martínez; Armando Ariza-Castolo; Rosalinda Contreras

• Book ID: 102525824
• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 440 KB
• Volume: 31
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1260310207

✦ Synopsis

Abstract

Some N‐BH~3~, N‐BF~3~, N^+^‐CH~3~ and N^+^‐H imidazole derivatives have been prepared and their ^13^C, ^11^B and ^1^H NMR spectra studied. The effect of the different substituents was analysed. The isolobal character of the N‐BH~3~ and N‐CH~3~ derivatives is reflected in their spectra. In the ^13^CH coupled spectra of N‐borane adducts, the hydrides appear to be coupled with the heterocyclic carbon atoms. The C‐4 chemical shift value is indicative of the nature of the N‐substitution: lone pair (128–130 ppm), BH~3~ (126–128 ppm), BF~3~ and [CH~3~]^+^ (122–124 ppm) or [H]^+^ (117–119 ppm). The latter values allowed the chemical shifts of frozen imidazole to be estimated: 128 ppm for C‐4 and 117 for C‐5.