Crystal structure of hydrazone form of 1-butyl-3-cyano-6-hydroxy-4-methyl-5-(2-thiazolylazo)-2-(1H)-pyridone

The structural results clearly indicate that 1-butyl-3-cyano-6-hydroxy-4-methyl-5-(2-thiazolylazo)-2(1H)-pyridone, (C₁₄H₁₅N₅O₂S), exists primarily as the hydrazone tautomer in the solid state. The molecule is nearly planar not regarding the butyl group. Some of the bond lengths and angles are distorted due to π-electron delocalization and strain. A strong intramolecular N-HℜO hydrogen bond was found [N⋯O = 2.53(1)Å]. The crystallographic parameters are as follows: triclinic P1̄, a = 5.972(4)Å, b = 7.732(5)Å, c = 17.348(9)Å, α = 85.62(5)0, β = 79.24(6)0, γ = 78.41(7)0, V = 770.4(9)ų, Z = 2, D_c = 1.37 g cm^-3, μ(MoK_α) = 2.1 cm^-1, R = 0.045, G.O.F. = 1.78.