1512 N-Z-L-Pro-D-Ala-OMe BENEDETTI, E., CIAJOLO, A., DI BLASIO,B., PAVONE,V., PEDONE, C., TO~OLO, C. & BONO~,, G. M. (1979a). Macromolecules, 12, 438-445. BENEDEa~, E., CIAJOLO, A., DI BLASIO, B., PAVONE,V., PEDONE, C., TONIOLO,C. & BONORA,G. M. (1979b). Int. J. Pept. Protein Res. 14, 130-142. BENEDETIa, E., C'L~OLO,M. R. & MAISTO, A. (1974). Acta Cryst. B30, 1783-1788. BENEDETH, E., PEDONE, C., TONIOLO, C., DUDEK, M., NEMETHY, G. & SCHERAGA,J. A. (1983). Int. J. Pept. Protein Res. 21, 163-181. BOSCH, R., SCHMIa'r, H., JUNG, G. &WtNTER, W. (1984). Acta Cryst. C40, 1096-1098. CARVER,J. P. & BLOUT,E. R. (1976). Treatise on Collagen, Vol. I, edited by G. N. RAMACHANDRAN. New York: Academic Press. Enraf-Nonius (1979). Structure Determination Package. Enraf- Nonius, Delft, The Netherlands. FRIDRICHSONS,J. & MATHIESON,A. McL. (1962). Acta Cryst. 15, 569-577. GRATHWOHL,C. & WUTHRICH,K. (1976). Biopolymers, 15, 2025- 2041. ITOH, H., YAMANE, T. & ASHIDA, T. (1978i. Acta Cryst. B34, 2640-2643. JOHNSON, C. K. (1976). ORTEPII. Report ORNL-5138. Oak Ridge National Laboratory, Tennessee, USA. KAMWAYA, M. E., OSTER, O. & BRADACZEK, H. (1981). Acta Cryst. B37, 1564-1568. KARTHA, G., ASHIDA, T. & KAKODO, M. (1974). Acta Cryst. B30, 1861-1866. KOJIMA, T., KIDO, T., ITOH, H., YAMANE,T. & ASHIDA,T. (1980). Acta Cryst. B36, 326-331. KOJIMA, T., TANAKA, I. & ASHIDA, T. (1982). Acta Cryst. B38, 221-225. KRAOSE, J. A. & EGGLESa'ON,D. S. (1990). Unpublished results. MAIN, P., FIsKE, S. J., HULL, S. E., LESSINGER,L., GERMAIN,G., DECLERCQ, J.-P. & WOOLFSON,M. M. (1980). MULTAN80. A System of Computer Programs for the Automatic Solution of Crystal Structures from X-ray Diffraction Data. Univs. of York, England, and Louvain, Belgium. MATSUZAKI, T. (1974). Acta Cryst. B30, 1029-1036. NAIR, C. M. K. & VUAYAN, M. (1981). J. Indian Inst. Sci. 63, 81-103. NARULA, P., PATEL, H. C. & SINGH, T. P. (1988). Biopolymers, 27, 1595-1606. PANNEERSELVAM, K., CHACKO,K. K. & VEENA, K. R. (1990). Acta Cryst. C46, 81-84. PATEL, H. C., SINGH, T. P., CHAUHAN, V. S. & KAUR, P. (1990). Biopolymers, 29, 509-515. PRECIGOUX, G., GEOFFRE, S., HOSPITAL, M. & LEROY, F. (1982). Acta Cryst. B38, 2172-2176. RUDKO, A. D. & LOW, B. W. (1975). Acta Cryst. B31, 713-725. SABESAN, M. N. & VENTATESAN, K. (1971). Acta Cryst. B27, 1879-1883. SCHWEIZER,W. B. & DUNITZ, J. D. (1982). Helv. Chim. Acta, 65, 1547-1554. SINGH, T. P., NARULA, P., CHAUHAN,V. S., SHARMA, A. K. & HINRICHS,W. (1989). Int. J. Pept. Protein Res. 33, 167-172. STEWART, R. F., DAVlDSON, E. R. & SIMPSON,W. T. (1965). J. Chem. Phys. 42, 3175-3187. SUGINO, H., TANAKA, I. & ASHIDA, T. (1978). Bull. Chem. Soc. Jpn, 51, 2855-2861. TANAKA, I. & ASHIDA,T. (1980). Acta Cryst. B36, 2164-2167. TANAKA, I., ASHIDA, T., SHIMONISHI, Y. & KAKUDO, M. (1979). Acta Cryst. B35, 110-114. TRIKHA, J., PATEL, J. C. & SINGH, T. P. (1990). Acta Cryst. C46, 74-78. U•KI, T., ASHIDA,T., KAKUDO, M., SASADA, Y. & KATSUBE, Y. (1969). Acta Cryst. B25, 1840-1849. UEKI, T., BANDO, S., ASHIDA, T. & KAKUDO, M. (1971). Acta Cryst. B27, 2219-2231. VALLE,G., CRISMA,M., TONIOLO,C., Yu, K.-L. & JOHNSON,R. L. (1989). J. Chem. Soc. Perkin Trans. 2, 83-87. VmET, J., COLLET, A., PICHON-PESME, V. & AUBR£, A. (1988). New J. Chem. 12, 253-256. WALKER, N. & STUART,D. (1983)~ Acta Cryst. A39, 158-166. YAMADA, Y., TANAKA, I. & ASHIDA, T. (1980). Acta Cryst. B36, 331-335. YAMADA, Y., TANAKA, I. & ASHIDA, T. (1981). Bull. Chem. Soc. Jpn, 54, 69-72. YAMANE, T., ASHIDA, T., SmMONiSrn, K., KAKUDO, M. & SASADA, Y. (1976). Acta Cryst. B32, 2071-2076. YAMANE,T., SHIRAISHI, Y. & ASHIDA, T. (1985). Acta Cryst. C41, 946-950. ZACHAmASEN,W. H. (1963). Acta Cryst. 16, 1139-1144. Acta Cryst. (1991). C47, 1512-1515 6-Amino-l,3-dimethyl-5-(2-ethylphenylazonio)uracil Bromide Dihydrate BY R. IOVEI~S AND M. R. SUNDBERG Division of Inorganic Chemistry, Department of Chemistry, University of Helsinki, Vuorikatu 20, SF-O01 O0 Helsinki, Finland AND J. RUIZ AND E. COLACIO Departamento de Quimica Inorgfnica, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain (Received 31 August 1990; accepted 20 November 1990) Abstract. CI4H18NsO~-.Br-.2H20, Mr=404"3, tri- clinic, P1, a=7"1738 (8), b= 10.110(2), c= 13.394(2)A, a=70"34(1), /3 =75"61 (1), y= 79"34 (1)°, V= 880"6 (2)/~3, Z = 2, Dx = 1-52 g cm-3, graphite-monochromatized Mo Ka radiation, ,t = 0.71069 A, /z = 27-3 cm-1, F(000) = 416, T = 298 K, R = 0.052 for 2640 observed reflec- tions. The bulky organic cation is essentially co- planar and the protonation takes place at the azo nitrogen N(8). The additional proton participates in 0108-2701/91/071512-04503.00 © 1991 International Union of Crystallography