Synthesis, crystal structures, and properties of isomers of 3,5-dinitro-(4-methoxyphenyl)aminobenzoyl (p-bromophenyl)amide

The syntheses of the para and ortho isomers of 3,5-dinitro-(4-methoxyphenyl)aminobenzoyl (p-bromophenyl)amide (I and II, respectively) are carried out. The structures and physicochemical properties of these isomers are investigated. It is found that isomer I exhibits a higher melting temperature (Tm) and a lower solubility than those for isomer II. The electronic absorption spectra indicate a higher degree of conjugation (resulting in the formation of quinoid-like structures) for molecule I as compared to molecule II. The physicochemical properties of compounds I and II correlate with their crystal structures. Crystals of compound I are triclinic; a=9.851(1), b=9.884(1),and c=11.183(2) A; α=90.45(1) deg., β=115.30(1) deg., and γ=90.68(1) deg.; V=948.2 A3; sp. gr. P1-bar; and Z=2. Crystals of compound II are orthorhombic; a=4.884(1), b=14.561(3),and c=27.601(6) A; α=β=γ=90 deg.; V=1962.9(7) A3; sp. gr. P212121; and Z=4. In addition to the usual van der Waals interactions, structure I is characterized by one intramolecular and two weak intermolecular hydrogen bonds that give rise to the centrosymmetric dimer formed by two elongated molecules of compound I. In structure II, the only intramolecular hydrogen bond is revealed