Substituent effects in trans-p,p'-di­substituted azo­benzenes: X-ray structures at 100 K and DFT-calculated structures

The crystal and mol­ecular structures of two para-substituted azo­benzenes with [pi]-electron-donating -NEt₂ and [pi]-electron-withdrawing -COOEt groups are reported, along with the effects of the substituents on the aromaticity of the benzene ring. Density functional theory (DFT) calculations were performed to analyse the differences in the geometry and aromaticity of the studied compounds in the crystalline state and for the isolated mol­ecules.