Twisted imide bond in noncyclic imides. Synthesis and structural and vibrational properties of N, N -bis(furan-2-carbonyl)-4-chloroaniline

Abstract

A novel imide compound (C 16H 10ClNO 4) was synthesized in a single step by the reaction of 2-furoic acid with 4-chloroaniline in a 2:1 molar ratio using carbonyldiimidazole (CDI) in dry THF. The structure was supported by spectroscopic and elemental analyses and the single-crystal X-ray diffraction data. Crystallographic studies revealed that the compound crystallized in a monoclinic system with space group P2 1/c and unit cell dimensions a = 12.2575(5) Å, b = 7.7596(2) Å, c = 15.0234(7) Å, α = γ = 90°, β = 92.771(4)°, V = 1427.25(10) Å 3, Z = 4. The imide bond is twisted, and the O=C-N-C(O) units deviate significantly from planarity with dihedral angles around the imide group reaching ca. -150.3° (C1-N1-C2-O21 = -148.8° and C2-N1-C1-O11 = -151.9°). The nonplanarity of the imide moiety and the related conformational properties are discussed in a combined approach that includes the analysis of the vibrational spectra together with theoretical calculation methods, especially in terms of natural bond orbital (NBO) calculations.