STRUCTURAL STUDIES OF PUSH-PULL BUTADIENES

Compound (1), ethyl 2-cyano-5-dimethylamino-3-methyl-2,4-pentadienoate, C11H16N202, M(r) = 208.26, monoclinic, P2(1)/n, a = 7.679 (2), b = 13.368 (2), c = 11.756 (2) angstrom, beta = 92.62 (2)-degrees), V = 1205.5 (4) angstrom3, Z = 4, D(x) = 1.15 g cm-3, lambda(CuKalpha) = 1.5418 angstrom, mu = 6.15 cm-1, F(000) = 448, T = 293K, R = 0.062 for 1721 unique reflections. Compound (II), 4,4-bis(methylthio)-2-phenyl-1,3-butadiene-1,1-dicarbonitrile, C14H12N2S2, M(r) = 272.38, triclinic, P1(BAR), a = 8.833 (1), b = 9.419 (2), c = 9.520 (1) angstrom, alpha = 106.77 (1), beta = 93.14 (1), gamma = 109.61 (1)-degrees, V = 704.2 (2) angstrom3, Z = 2, D(x) = 1.28 g cm-3, lambda(Cu Kalpha) = 1.5418 angstrom, mu = 32.29 cm-1, F(000) = 284, T = 293 K, R = 0.062 for 2059 unique reflections. Compound (III), ethyl 2-cyano-5-dimethylamino-3-phenyl-2,4-pentadienoate, C16H18N2O2, M(r) = 270.33, mono-clinic, C2/c, a = 17.468 (1), b = 13.753 (4), c = 15.218 (1) angstrom, beta = 125.49 (1)-degrees, V = 2976.7 (9) angstrom3, Z = 8, D(x) = 1.21 g cm-3, lambda(Cu Kalpha) = 1.5418 angstrom, mu = 6.12 cm-1, F(000) = 1152, T = 293K, R = 0.055 for 2211 unique reflections. Compound (IV), 4-dimethylamino-4-methylthio-3-phenyl-1,3-butadiene-1,1-dicarbonitrile, C15H15N3S, M(r) = 269.36, monoclinic, P2(1)/n, a = 9.951 (1), b = 10.040 (1), c = 14.764 (2) angstrom, beta = 98.67 (1)-degrees, V = 1458.9 (2) angstrom3, Z = 4, D(x) = 1.23 g cm-3, lambda(Cu Kalpha) = 1.5418 angstrom, mu = 18.37 cm-1, F(000) = 568, T = 293 K, R = 0.052 for 2479 unique reflections. The influence of different electron donor-acceptor pairings on the molecular geometry is discussed.