| Abstract | 2-{3-Cyano-4-[4-(N-formyl-anilino)-trans-1,3-butadien-yl]-5,5-dimethyl-2, 5-dihydro-furan-2-yl-idene}propane-dinitrile, C22H18N4O2, (I), and 2-{3-cyano-4-[6-(N-formyl-anilino)-trans,trans-1,3,5-hexa-trien-yl]-5, 5-dimethyl-2,5-dihydro-furan-2-yl-idene}propane-dinitrile, C24H20N4O2, (II), show the alternating single/double-bond behaviour of push-pull chromophores. In the two structures, the planar polyene chains are twisted with respect to the furanyl-idene ring by 18.2 (2) and 12.4 (2)°, respectively. Comparison with structures of related and parent mol-ecules shows subtle but consistent bond-length variations consistent with charge-delocalized structures. Crystal cohesion is provided by various sets of hydrogen bonds, viz. C - Hmethyl⋯Ncyano and bifurcated (C=C - H)2⋯O=C in (I), and C - Hmethyl/phenyl⋯O and C=C - H⋯Ncyano in (II). © International Union of Crystallography 2007. |
