Synthesis and Crystal Structure of 1,1′-di(ethylpropionato)-2,2′-biimidazole, a Macromolecular Precursor

1,1,′-Di(ethylpropionato)-2,2′-biimidazole, C ₁₆ H ₂₂ N ₄ O ₄ , crystallizes from ice-cold ethanol in the space group P1sup>– , with a = 4.6742(9), b = 9.1119(13), c = 10.175(2) Å, α = 96.22(1), β = 96.29(2), γ = 97.53(1)°, and Z = 1. The molecule crystallizes with coplanar rings and the substituents assume a trans conformation with a center of inversion between the bridging carbon atoms.