Structure of 1,5-Bis(dimethylamino)-1,5-diphenyIpentadienylium Perchlorate and Modelling of Pentadienylium Salts (Cyanine Dyes)

摘要

C_(21)H_(25)N_2~+.ClO_4~- (orange crystals), Mr = 404.9, orthorhombic; P2{22, a = 7.810(2), b = 15.007(3), c = 18.326 (3) A, V = 2147.8 (7) A3. Graphite-monochromated Mo Ka source at room temperature; A = 0.71069 A, i = 0.22 mm-', Z = 4; F(000) = 856, Dx = 1.25 g cnT3, R = 0.057 for 1392 independent data. As for the unsubstituted pentamethinium dyes, the chain lies in an all-trans planar configuration. Molecular modelling calculations reproduce the X-ray structure with good accuracy, even in the case of more crowded pentadienylium cations, i.e. 1,5-bis(dimethylamino)-l,3)5-triphenylpentadienylium perchlorate.