Crystal structure of 4,5-dihydro-6-(2-thienyl)-3(2H) pyridazinone azine, (C16H16N16S2)

M_r = 484, monoclinic, P 2₁/c, a = 5.567(1), b = 7.857(2), c = 19.194(10) Å, β = 99.97(3)°, V = 826.9 ų, Z′ = 2, D_x = 1.43 g · cm⁻³, F(000) = 372, MoKα, λ = 0.71069 Å, μ = 0.328 mm⁻¹, final R = 0.055 for 889 observed reflections, T = 293 K. The compound was prepared from a direct unusual reaction of 6-(2-thienyl)-2,3,4,5-tetrahydropyridazine-3-one with hydrazine hydrate. The structure was solved by direct methods and refined by full-matrix least squares. The molecule in the solid state consists of a dimer with its two equivalent halves related by a center of symmetry at the middle of the N N bond. Each molecular fragment is nearly planar and the N N bond between the two halves is 1.296(5) Å indicating that it is a partial double bond.