Crystal Structure and Related Properties of Phenothiazine Cation Radical-Hexachloroantimonate. Monoclinic(I) Form

Abstract

Three forms of crystals were obtained from mixed solutions of phenothiazine and SbCl5; the crystal structure of the monoclinic(I) modification was determined using 2827 reflections at room temperature. Crystal data: (C12H9NS)+·SbCl6−, F.W.=533.7, monoclinic, a=16.253(3), b=14.334(1), c=15.786(3) Å, β=104.07(1)°, space group C2/c, Dm=2.00, Dx=1.99 g cm−3, Z=8, μ=25.73 cm−1 (Mo Kα). The structure was solved by the heavyatom method and refined by block-diagonal least-squares method to R=0.072. The crystal consists of phenothiazine cation radicals(PT+·) and hexachloroantimonate anions(SbCl6−), and every ion exists as a monomer in the crystal. Each SbCl6− forms a distorted octahedron. The two C–S distances of PT+· are 1.705 and 1.711 Å, and the C–S–C angle is 103.9°. The dihedral angle between the two outer phenyl rings of PT+· is 176.5°. From the ESR measurements of a single crystal, three principal g-values were determined: g1=2.003, g2=2.007 and g3=2.008. The direction of g1 is normal to the molecular plane of PT+·. These facts suggest some π-delocalization in the central ring of PT+·. Absorption spectra polarized parallel to the molecular plane of PT+· are very similar to the poly crystalline reflection spectra of PT+· salts obtained by other authors, and there are no intense bands in the spectra polarized perpendicular to PT+· molecular plane over the wave number range 10 to 27×103 cm−1.