Hydrogen bonding patterns in a series of 1-arylcycloalkanecarboxamides

Single-crystal structures of five 1-arylcycloalkanecarboxamides, viz. 1-phenylcyclopentanecarboxamide (1), 1-phenylcyclohexanecarboxamide (2), 1-(2-fluorophenyl)cyclohexanecarboxamide (3), 1-(2-chlorophenyl) cyclohexanecarboxamide (4) and 1-(2-bromophenyl)-cyclohexanecarboxamide (5), are reported. The primary hydrogen-bonded motif consists of centrosymmetric or non-centrosymmetric R²₂(8) dimers between the carboxamide functional groups. In compound 1, the dimers are further linked by hydrogen bonds to form infinite two-dimensional sheets, while in 4 and 5 additional hydrogen bonding with molecules not involved in dimer formation links the dimers into infinite chains. The cycloalkane rings in the five compounds adopt noticeably different conformations. As a consequence of these various effects, none of the five compounds is isostructural.