One-pot treatment of commercially available 1,3,3-tributoxy-2-cyanopropene with 2 equivalents of primary aromatic amines readily afforded 1,5-diaryl-1,5-diaza-3-cyanopenta-1,3-dienes. UV properties varied as steric size of the orthosubstituent in the N-aryl units increased. X-ray crystallographic analyses indicated preferable conformation of these compounds, and the twist angles between 1,5-diazapentadiene and aromatic units were measured. The relationship between the twisted angles and UV absorptions was rationalized by MO calculation, and the UV peak wavelengths are useful for the estimation of the twisted angles. A novel tetracoordinate diaryl-1,5- diazapentadiene was prepared. UV spectrum for its lithium complex in CHCl 3 supported that the complex had a twisted conformation of the aryl units because the two etharial oxygen atoms coordinated to lithium cation. © 2012 The Chemical Society of Japan.