IR spectral and structural changes caused by the conversion of 3-hydroxybenzaldehyde into the oxyanion

Abstract

The spectral and structural changes, caused by the conversion of the 3-hydroxybenzaldehyde molecule into the corresponding oxyanion have been studied by IR spectra, and MP2 and DFT force field calculations. The conversion causes a 13 cm −1 decrease in the frequency of the carbonyl stretching band ν CO, a 1.3-fold increase in its integrated intensity, strong intensity increases (2.1–5.3-fold) of the aromatic skeletal ν 8 and ν 19 as well as formyl ν CH bands. According to the calculations the oxyanionic charge is delocalized over aldehyde group (0.37 e −), phenylene ring (0.12 e −) and oxyanionic center (0.52 e −). The conversion into the oxyanion leads to geometry changes in the whole species, but it remains planar.