Effect of Substituent on Crystal Structures of N-(Substituted- phenyl)-2,2,2-Trichloroacetamides, 2/3/4-XC 6 H 4 .NHCO.CCl 3 (X = Cl, NO 2 or CH 3 )

Abstract

Abstract The crystal structures of N-(substitutedphenyl)-2,2,2-trichloroacetamides of the type 2/3/4-XC6H4.NHCO.CCl3 (X = CI, NO2 or CH3), namely, N-(3-nitrophenyl)-2,2,2-trichloroacetamide,3-NO2C6H4.NHCO.CCl3 (m-NO2PhTCA); N-(4-nitrophenyl)-2,2,2-trichloroacetamide,4-NO2C6H4.NHCO.CCl3 (p-NO2PhTCA); N-(2-chlorophenyl)-2,2,2-trichloroacetamide,2-ClC6H4.NHCO.CCl3 (o-ClPhTCA) and N-(4-chlorophenyl)-2,2,2-trichloroacetamide, 4-C1C6H4.NHCO.CCl3 (p-ClPhTCA) have been determined at room temperature. The presentdata are analysed along with our earlier crystal structures of N-(2-nitrophenyl)-2,2,2-trichloroacetamide,2-NO2C6H4.NHCO.CCl3 (o-NO2PhTCA); N-(4-methylphenyl)-2,2,2-trichloroacetamide,4-CH3C6H4. NHCO.CCl3 (p-CH3PhTCA); N-(phenyl)-2,2,2-trichloroacetamide,C6H5.NHCO.CCl3 (PhTCA); N-chloro-N-(phenyl)-2,2,2-trichloroacetamide, C6H5.NClCO.CCl3(NClPhTCA); and finally with N-(phenyl) acetamide, C6H5.NHCO.CH3 (PhA). The crystal type,space group, formula units and lattice constants in Å of the new structures are; m-NO2PhTCA:triclinic, PI, Z = 4, a = 7.493(3), b = 9.992(3), c = 15.225(5), α = 84.16(2)°, β = 82.59(2)°, γ =84.92(2); p-N02PhTCA: monoclinic, P21/n, Z = 4, a = 5.807(2), b = 15.354(6), c = 12.475(5),β = 92.28(2)°; o-ClPhTCA: orthorhombic, Pna21, Z = 4, a = 8.769(2), b = 12.838(3), c = 9.578(2)and p-ClPhTCA: orthorhombic, Pbca, Z = 8, a = 9.742(4), b = 10.031(4), c = 23.110(9). Thecompounds, m-NO2PhTCA, o-NO2PhTCA and p-CH3PhTCA show two molecules each in theirasymmetric units. This is in agreement with the multiple lines observed in the 35Cl NQR spectraof the latter two compounds. But the presence of two molecules in the asymmetric unit of m-NO2PhTCA indicates that it may undergoe a phase transition below room temperature. The bondlengths and bond angles are normal except for some deviations. The presence of strong electronwithdrawing group at the ortho position of the phenyl ring and N-chlorination of the amide willhave significant effect on some bond distances and bond angles.