Solvatocfaromism of Heteroaromatic Compounds:XXV.Effect of Bifurcate Hydrogen Bond with a Weak Intramolecular Component on the IR,NMR,and UV Spectra of 2,6-Dibromo-4-nitrophenol

摘要

Dissolution of 2,6-dibromo-4-nitrophenol in aprotic protophilic solvents forms a three-center solvation H-complex with a sharply weakened intramolecular hydrogen bond.This weakening is associated with a deformation of the bond angle of the hydroxy group.It is only on interaction with weak 7i-bases that the intramolecular component of the bifurcate hydrogen bond appreciably affects the spectral position of the OH stretching vibration band;this results in a nonlinear dependence between vOH and the Kamlet-Taft sol-vatochromic parameter.