Authors: Pinheiro, A.C.; De Souza, M.V.N.; Wardell, J.L.; Wardell, S.M.S.V.
Source: Zeitschrift für Kristallographie, v. 227, p. 167-177, 2012.
Publisher: De Gruyter
Abstract
The crystal structures of three N-(arenecarbonyl)-N,N′-dicyclohexylureas, [1: ArCO-N(cyclohexyl)-CO-NH-cyclohexyl: (R = Ph (1a), pyridin-3-yl (1c) and pyrazinyl (1e)] are reported from data collected at 120K. Comparison of the new findings with published data for the three compounds indicates three forms have been recognized for this group of compounds: an orthorhombic-form [P212121] and two triclinic [P-1] forms – triclinic–I and triclinic–II. Orthorhombic and triclinic–II phases have been determined for compound, 1a, triclinic–I and triclinic–II forms for compound 1c, and just the orthorhombic form for compound, 1e. Orthorhombic 1a and 1e are isostructural, as are triclinic–II 1a and 1c. The asymmetric unit for the orthorhombic form contains just a single molecule, while the molecules are linked into chains, C(7)R22(11), via strong N—H ··· O and weaker C—H ··· O intermolecular hydrogen bonds. The asymmetric unit for triclinic–I consists of two independent molecules, molecules A and B, which are linked alternatively into chains, C(8)R22(16), via N—H ··· N and C—H ··· O intermolecular hydrogen bonds in the direction of the a axis: such chains are linked via C—H ··· O hydrogen bonds. The asymmetric unit of the triclinic–II phase also comprises two independent molecules, molecules A and B, which are also linked alternatively into chains, C(8), but only via N—H ··· O hydrogen bonds, with other intermolecular interactions of the C—H ··· π type also present.Keywords: DCC reactions; polymorphs; hydrogen bonding; supramolecular arragements Document Type: Research Article DOI: http://dx.doi.org/10.1524/zkri.2012.1447 Publication date: 19 de Janeiro de 2012
