Structural investigations of C-nitrosobenzenes .1. Solution state H-1 NMR studies

Ambient and low temperature H-1 NMR spectra of a wide range of 3- and 4-monosubstituted, and some di- and tri-substituted C-nitrosobenzenes have enabled -N=0 substituent constants for the static and rotating ring molecules to be calculated, This has provided information on the shielding anisotropy of the N=0 group which In turn leads to the firm identification of the monomeric and dimeric solution species, In all cases lowering the solution temperature enhances the relative populations of dimers to monomers, with the (Z)-azodioxy dimer being preferred over the (E)-form, irrespective of the nature of the solid state dimeric structure.