CRYSTAL AND MOLECULAR-STRUCTURE OF THE PHENYL-TRIMETHINE-MEROCYANINE C9ONH9

The phenyl‐trimethin‐merocyanine crystallizes in the space group I 4 with 8 molecules per unit cell. The lattice constants are a = b = 16.121 Å, c = 6.549 Å, α = β = γ = 90°. The intensities were measured with an automatic single crystal diffractometer. The solution of the structure was obtained by applying the convolution molecule method and the R‐value method. The refinement was performed by least‐squares blockdiagonal method to an R‐value of 7.2% for 1067 independent reflexions. The C–C‐bond lengths within the plane of the trimethin chain alternate as in the molecule structure of the morpholylpentamethine‐merocyanine and thus point to a distinct polyenic behaviour. The valence angles within the chain alternate as well. This property indicates a polymethinic behaviour of the molecule. The geometry of the molecule proves the merocyanines to have an intermediate position between the polymethinic and the polyenic state. For a more detailed discussion we refer to the discussion of the morpholyl‐pentamethine‐merocyanine structure. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim