HalogenatedC,N-diarylacetamides: molecular conformations and supramolecular assembly

Abstract

The structures of four halogenatedN,2-diarylacetamides are reported and compared with a range of analogues.N-(4-Chloro-3-methylphenyl)-2-phenylacetamide, C15H14ClNO, (I), andN-(4-bromo-3-methylphenyl)-2-phenylacetamide, C15H14BrNO, (II), are isostructural in the space groupP\overline{1}. The molecules of (I) and (II) are linked into chains of rings by a combination of N—H...O and C—H...π(arene) hydrogen bonds. The molecules ofN-(4-chloro-3-methylphenyl)-2-(2,4-dichlorophenyl)acetamide, C15H12Cl3NO, (III), andN-(4-bromo-3-methylphenyl)-2-(2-chlorophenyl)acetamide, C15H13BrClNO, (IV), are linked into simpleC(4) chains by N—H...O hydrogen bonds, but significant C—H...π(arene) interactions are absent. TheN-aryl groups in compounds (III) and (IV) adopt a different orientation, byca180°, from that of the corresponding groups in compounds (I) and (II), but otherwise the conformations of (I)–(IV) are very similar. Comparisons are drawn between compounds (I) and (IV) and a range of analogues of the typeR1CH2CONHR2, whereR2represents a halogenated aryl ring andR1represents either another halogenated aryl ring or a naphthalen-1-yl unit.