Molecular geometry of (E)- and (Z)-9-(β-Styryl)anthracenes

Abstract

The molecular structures of (Z)-9-(8-styryl)anthracene, C₂₂H₁₆,(I),(E)-9-(P-styryl)anthracene, (2), and the photo-Diels-Alder dimer of 9-phenylethynylanthracene, C₄₄H₂₈, (3), containing a (Z)-9- (β-styryl) anthracene moiety of limited mobility have been determined by X-ray diffraction. Crystals of (1) are monoclinic, P2₁/c, a 5.507(4), b 13.050(7), c 21.425(10)Å, β 95.73(5)º, Z 4; R was 0.047 for No 1604 independent 'observed' reflections. Crystals of (2) are monoclinic, P21/n, a 11.77(1), b 24.35(2), c 5.503(5) Å, β 107.38(7)º, Z 4; R 0.050 for No 1100. Crystals of (3) are monoclinic, P2₁/c, a 10.719(7), b 18.627(8), c 15.509(8) Å, β 101.10(5)º, Z 4; R 0.070 for No 1055. Increase in angle between the plane of the anthracene and the plane of the ethylenic double bond (78.4, 65.5, 81.9º respectively) is reflected in the electronic absorption spectra by an enhancement of the fine structure typical of the anthracene chromophore.