Structure of 1,5-bis(dimethylamino)-1,5-diphenylpentadienylium perchlorate and modelling of pentadienylium salts (cyanine dyes)

摘要

C21H25N2+.ClO4- (orange crystals), M(r) = 404.9, orthorhombic; P2(1)2(1)2(1), a = 7.810 (2) 6 = 15.007 (3), c = 18.326 (3) Angstrom, V = 2147.8 (7) Angstrom(3). Graphite-monochromated Mo K alpha source at room temperature; lambda = 0.71069 Angstrom, mu = 0.22 mm(-1), Z = 4; F(000) = 856, D-x = 1.25 g cm(-3), 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 Xray structure with good accuracy, even in the case of more crowded pentadienylium cations, i.e. 1,5-bis(dimethylamino)-1,3,5-triphenylpentadienylium perchlorate.