Katsuhiko Ueno

p-Phenylenediacrylic acid diphenyl ester (p-PDAPh), a photopolymerizable crystal

C24H1804, M r = 370.4, monoclinic, P2~/c, a = 6.935 (1), b = 18.611 (6), c = 7.570 (2) A, f l = 101.88 (2) °, Z = 2, D x = 1.287, D m = 1.285 g cm -s. Despite comparatively poor molecular planarity, the molecules form the plane-to-plane stack which is a common feature of the packing of photopolymerizable crystals of this kind. In the stack, double bonds related by a centre of symmetry have a closest approach of 3.928 A. . Introduction. p-PDAPh was synthesized according to Suzuki, Suzuki, Nakanishi & Hasegawa (1969). Colourless plate-like crystals were grown from a benzene solution by slow evaporation. The specimen used was a fragment of a plate 0.10 x 0.05 x 0.03 mm. The space group was determined from photographs. The precise lattice constants and intensity data were obtained from measurements on a Rigaku computer-controlled four-circle diffractometer, with graphite-monochromatized Mo Ka radiation. All reflexions within the range 20 1.5) were determined in terms of three symbols. One of the eight E maps revealed the positions of all the non-hydrogen atoms. The parameters were refined by the blockdiagonal least-squares method using w = 0.5 for IFol _ 1.0. Isotropic H atoms were first located geometrically and then refined. The final R value was 0.057.* Atomic scattering factors were taken * Lists of structure factors, thermal parameters and deviations of atoms from some least-squares planes have been deposited with the British Library Lending Division as Supplementary Publication No. SUP 33377 (6 pp.). Copies may be obtained through The Executive Secretary, International Union of Crystallography, 13 White Friars, Chester CH 1 1NZ, England. Table 1. Fractional atomic coordinates (× 104for C, O; × 103 for H) Estimated standard deviations are in parentheses.

Stizolamine chloride: a novel amine isolated from Stizolobium hassjoo

CvH~zNsOz. CI, FW 233.6, monoclinic, C2/c,a= 18.441 (2),b = 7.149 (1),c = 15.138 (2)/k, fl = 95.30 (I) °, Z = 8, D x = 1.56, D,, = 1.55 g c m -s, R = 0.039 for 1851 reflexions. X-ray analysis confirmed that stizolamine is l-methyl-3-guanidino-6hydroxymethylpyrazin-2-one. The pyrazine ring and guanidyl group are nearly coplanar (the dihedral angle between them being 2.9°). In the crystal, twodimensional double-layered sheets are formed by one N H . . . O = C , one O H . . . C I and four N H . . . C I hydrogen bonds. Introduction. Stizolamine was isolated as a novel amine from Stizolobium hassjoo and some other plants (Yoshida & Hasegawa 1977). From chemical studies the structure was supposed to be 1-methyl-3-guanidino6-hydroxymethylpyrazin-2-one (Yoshida, 1977). In order to confirm this, the crystal structure analysis was undertaken as a part of the studies on the metabolites of stizolobium. Crystals were prepared from aqueous solution as pale-yellow prisms. The space group was indicated from oscillation and Weissenberg photographs to be C2/c or Cc (systematic absences: h+k odd for hkl and l odd for hOl). The lattice constants and intensity data were obtained from measurements on a crystal, 0-2 x 0.3 x 0.15 mm, taken on a Rigaku four-circle diffractometer with graphite-monochromatized Cu K~t radiation. The 20-o3 scan mode was applied with a scan rate of 4 ° (20) min -~ and range (1-0 + 0.5 tan0) °. Stationary background counts were accumulated for 10 s before and after each scan. Of 1925 independent reflexions measured within 20 _ 20.0. Atomic scattering factors were taken from 0.97(4) (u(~ .~A(~ ~(4) 1.~~ (&h ~ _ 11.229(2) .1.416(2) ( N ~