Structure of 5-(p-n-Glucopyranosyl)barbituric Acid Trihydrat

113 8 C 24H29BrN209 S positional molecular parameters are lower when molecular flexibility is included, but a higher value of the overall molecular rotation is observed in this case. The torsional angles of selected molecular fragments show in some cases (the ethyl group and two of the acetyl chains) a larger deviation for the experimental values but inclusion of the Coulombic term does not appreciably improve the fit. These discrepancies between experimental and theoretical parameters of molecular subrotations and the above-cited cell expansion could be attributed to limitations of the force-field approach, in particular the assumed transferability of potential parameters. The authors thank Professor J. A. Galbis-P6rez for supplying the crystals and for helpful discussion on chemical aspects and Professor A. L6pez-Castro for collecting the diffractometer data. The present work is part of a research project supported by the CAICYT of the Spanish Government. References BURGOS, E. & BONADEO, H. (1977). Chem. Phys. Lett. 49, 475-478. CONDE, C. F., MILl.AN, M., CONDE, A. & MARQUEZ, R. (1985a). Acta Cryst. C41, 277-280. CONDE, C. F., MIL~, M., CONDE, A. & M.~RQUEZ, R. (1985b). Acta Cryst. C41, 1658-1662. CREMER, D. & POPLE, J. A. (1975). J. Am. Chem. Soc. 97, 1354-1358. ESTRADA, M. D., CONDE, A. & M.~.RQUEZ, R. (1983). Acta Cryst. C39, 1418-1421. ESTRADA, M. D., CONDE, A. & MARQUEZ, R. (1984). Acta Cryst. C40, 898-901. ESTRADA, M. D., CONDE, A. & M~,RQUEZ, R. (1986). Acta Cryst. C42, 454-457. GALmS-PfmEZ, J. A., PALACIOS-ALBAR1L~N, J. C., JIMI~NEZREQUEJO, J. L. & AVALOS-GONZ.~LEZ, M. (1984). Carbohydr. Res. 129, 131-142. GOVERS, H. A. J. (1975). Acta Cryst. A31, 380-385. HAMILTON, W. C. (1959). Acta Cryst. 12, 609-601. International Tables for X-ray Crystallography (1974). Vol. IV. Birmingham: Kynoch Press. (Present distributor D. Reidel, Dordrecht.) JOHNSON, C. K. (1965). ORTEP. Report ORNL-3794. Oak Ridge National Laboratory, Tennessee. MASON, A. & KREEVOY, M. M. (1955). J. Am. Chem. Soc. 77, 5808-5814. MIRSKAYA, K. V. (1973). Tetrahedron, 29, 679-682. MURRAY-RUST, P. & MOTHERWELL, S. (1978). Acta Cryst. B34, 2534-2546. NARDELLI, M. (1983). Acta Cryst. C39, 1141-1142. SKORCZYCK, R. (1976). Acta Cryst. A32, 447-452. STEWART, J. M., MACHIN, P. A., DICKINSON, C. W., AMMON, H. L., HECK, H. & FLACK, H. (1976). The XRAY76 system. Tech. Rep. TR-446. Computer Science Center, Univ. of Maryland, College Park, Maryland. TAYLOR, R. & KEr~ARD, O. (1982). J. Am. Chem. Soc. 104, 5063-5070. WILLIAMS, D. E. (1972a). Acta Cryst. A28, 84-88. WILtJAMS, D. E. (1972b). Acta Cryst. A28, 629-635. WILLIAMS, D. E. (1974). Acta Cryst. A30, 71-77. Acta Cryst. (1987). C43, 1138-1142 Structure of 5-(fl-D-Glucopyranosyl)barbituric Acid Trihydrate* BY M. MILLAN, C. F. CONDE, A. CONDE AND R. M,~RQUEZ Departamento de Optica y Seccidn de F[sica del Centro Coordinado del CSIC, Universidad de Sevilla, Spain (Received 17 September 1985; accepted 6 January 1987) Abstract. C10H15N3OT.3H20 , Mr= 343.3, monoclinic, P21, a = 10.883 (3), b = 12.497 (20), c = 10.553 (4) A, t= 91.05 (3) °, V= 1435 (2) A 3, Z=4, D m=1.57(2), D x=l.589Mgm -3, MoK~ 2= 0.7107/~, /t = 0.13 mm -~, F(000) = 728, T= 300 K, R = 0.064 for 2692 observed independent reflexions. The compound presents a zwitterionic structure in which the negative charge is delocalized in the system formed by the two carbonyl groups at C4 and C6 and the carbon atom C5 of the barbituric ring. In the two independent molecules in the asymmetric unit the pyranose ring adopts a 4C 1 conformation and the dihedral angles between the pyranose and barbituric * Barbituric acid is 2,4,6(1H,3H,5H)-pyrimidinetrione. 0108-2701/87/061138-05501.50 rings for the two molecules are 80.9 (3) and 90-3 (3) ° . The molecules are linked by an extensive threedimensional hydrogen-bonding network, involving the water hydration molecules, which stabilize the crystal structure. Introduction. The structure determination of the title compound (II) was undertaken as part of a continuing project on conformational details of C-nucleosides in the solid state. An easy synthesis of C-nucleoside derivatives of barbituric acids by reaction of aldoses with the barbituric acid has been reported (AvalosGonzfilez, 1981; Galbis-P6rez, Avalos-Gonz/dez, Jim~nez-Requejo & Palacios-Albarrfi.n, 1983). In this way, the reaction of barbituric acid with ~glucose © 1987 International Union of Crystallography M. MILLAN, C. F. CONDE, A. CONDE AND R. M,ARQUEZ 1139 yields the acyclic C-glycoside (I) or its cyclic analogue (II) by dehydration of the sugar side chain. After acetylation, the cyclic form was established from spectral data (UV, IR and ~H NMR). For the non-acetylated compound the acyclic form was initially supposed and an X-ray analysis was suggested to elucidate the molecular form; finally, the cyclic Cnucleoside structure was established. The X-ray structure of the analogous 5-fl-D-galactopyranosyl-l,3-dimethylbarbituric acid monohydrate has been reported (Mill~m, Conde, Conde & M/trquez, 1985) and the cyclic form was also established in that X-ray analysis. lographic programs of the XRAY70 system (Stewart, Kundell & Baldwin, 1970) used throughout.* Discussion. Fractional atomic coordinates and equivalent isotropic temperature factors (Hamilton, 1959) for non-hydrogen atoms are given in Table 1. A projection of the molecule A with lettering is shown in Fig. 1. Bond lengths and angles involving non-hydrogen atoms are shown in Table 2. For bonds involving H atoms, the mean values found are 1.07 (4),/k for C-H distances, 0.93 (5)/~ for O--H bond lengths and 1.08 (3)/~ for N--H distances. O H .~N,~ N f H 0 0 I H H COH O. /N-~ /O HO-C-H HO o "Y, "T" H-C-NH 3 HO N.~ " - I HO-C-H H " O I H-C-OH I H-C-OH I CH~OH (I) (II) * Lists of structure factors, anisotropic thermal parameters and H-atom parameters have been deposited with the British Library Document Supply Centre as Supplementary Publication No. SUP 43704 (29 pp.). Copies may be obtained through The Executive Secretary, International Union of Crystallography, 5 Abbey Square, Chester CH 1 2HU, England. Table 1. Atomic coordinates and equivalent isotropic Experimental. Crystals of the title compound, prepared Molecule A as previously described in the Organic Chemistry C l c2 Department of the University of Extremadura, were c3 kindly supplied by Professor J. Galbis. Colourless c4 c5 crystals in the form of prisms elongated along [001 ]. D m c6 C7 by flotation method. Crystal 0.04 x 0.14 x 0.17 mm. c8 Enraf-Nonius CAD-4 diffractometer equipped with c9 c10 graphite monochromator; cell dimensions obtained n~ from 25 reflexions in the range 2 < ~< 20 ° . Total of n2 N3 3768 independent reflexions (--14 <h _< 14, 0 < k < ol o2 15, 0 <l_< 16) measured in the 2 < 0<30 ° range o3 using o.r--20 scan technique. Three standard reflexions o4 o5 (600, 060, 006) monitored; variation in intensity less o6 than 4% of mean values. 1076 reflexions considered as o7 unobserved [I < 2or(/)]. No correction for absorption or Molecule a extinction. Structure solved by direct methods using Cll c21 MULTAN80 (Main, Fiske, Hull, Lessinger, Germain, c31 Declercq & Woolfson, 1980). The absolute configurac41 c51 tion was assumed on the basis of the configurations of c61 the compounds used in the synthesis. Full-matrix c71 c81 least-squares refinement; function minimized c91 ~w(IFol - I F c I) 2 with weighting scheme based on the c101nll statistical count criterion (w = 1/tr2). Difference Fourier n21 n31 synthesis revealed the H-atom positions; isotropic o~ temperature factor for each equal to that of the atom o2~ O31 bonded to it. Further least squares including positional o4~ o5~ parameters of the H atoms. At final convergence o6. A/a < 0.03 (for non-hydrogen atoms) with R = 0.064, o7~ wR =0.073, S = 2.2 for 541 variables refined. Max. and min. values in final difference density map 0.35 and -0.30 e A -3. Atomic scattering factors from International Tables for X-ray Crystallography (1974). Calculations carried out on a Univac 1100; crystalthermal parameters Ueq = ~ ~'i ~i a ~ a~ a ia jcos (a i. a j). x y z 0.5868 (10) 0.7982 (9) 0.8420 (8) 0.7631 (8) 0.9755 (7) 0.9954 (9) 1.1304 (8) 1.1945 (8) 1.1657 (8) 1.2277 (10) 0.6388 (7) 0-6702 (8) 0.9366 (7) 0-4793 (7) 0.8615 (7) 0.7956 (6) • 0365 (6) • 2012 (7) -3186 (7) • 1430 (7) 0.7144 (9) 0-9205 (9) 0.9692 (8) 0.8881 (8) • 0994 (8) • 1172 (7) • 2526 (8) • 3198 (8) • 2961 (7) • 3589 (lO) 0.7654 (7) 0.7947 (8) 1.0560 (7) 0.6043 (6) 0.9830 (7) 0.9202 (6) 1.1665 (6) 1.3303 (6) 1.4439 (6) 1.2718 (6) 0.8315 (11) 0.8174 (10) 0.8652 (11) 0.8946 (9) 0.7926 (1 I) 0.8078 (9) 0.7475 (11) 0.7180(9) 0.7626 (11) 0.8158 (8) 0.6415 (11) 0.8233 (8) 0.6123 (10) 0.8237 (8) 0.6681 (I 1) 0.7143 (9) 0.7884 (11) 0.7212 (10) 0.8532 (11) 0.6178 (10) 0.7683 (11) 0.7271 (8) 0.8813 (10) 0.8966 (8) 0.6021 (10) 0.9420 (8) 0.8423 (11) 0.8249 (9) 0.9174 (10) 0.9727 (8) 0.6859 (9) 0.6291 (6) 0.8038 (9) 0.7081 (6) 0.8038 (9) 0.4954 (7) 0.6430 (10) 0.7250 (8) 0-5000 0.8102 (7) 0.0615 (11) 0.6741 (9) 0.0410 (11) 0.5907 (9) 0.1062 (10) 0.6887 (8) 0.1454 (11) 0.7821 (9) 0.1394 (10) 0.6854 (8) 0.2588 (I0) 0.6657 (8) 0.2874 (I0) 0.6595 (9) 0.2456 (I 1) 0.7771 (9) 0.1254 (10) 0.7887 (8) 0.0717 (11) 0.8981 (10) 0.1196(10) 0.7688(8) 0.0200 (I0) 0.5892 (8) 0.2926 (10) 0.5456 (8) 0.0463 (10) 0.6637 (7) 0.0045 (9) 0.5014 (7) 0.2028 (9) 0.8741 (7) 0.1078 (9) 0.7974 (6) 0.1223 (10) 1.0144 (7) 0.2730 (10) 0.7647 (8) 0.3982 (8) 0.6379 (7) Water molecules O8 0.4718 (7) 0.7032 (10) 0.5264 (8) 09 0.3793 (8) 0.7517 (12) 1.0469 (9) O10 0.4551 (8) 0.5010(11) 0.8810(9) O12 0.5055 (7) 0.4240 (11) 0.5360 (8) OI3 0.8091 (9) 0.3979 (10) 0.8952 (10) O14 0.7237 (9) 0.4726 (10) 0.6584 (9) Ue,(A ~ x 103) 30 (3) 26 (3) 21 (2) 23 (3) 20 (2) 23 (3) 21 (2) 23 (3) 26 (3) 31 (3) 29 (3) 29 (3) 27 (2) 43 (3) 40 (3) 28 (2) 26 (2) 34 (2) 39 (3) 3O (2) 25 (3) 23 (3) 21 (2) 22 (3) 21 (2) 20 (2) 22 (3) 21 (2) 21 (3) 30 (3) 26 (2) 28 (3) 26 (2) 34 (2) 30 (2) 28 (2) 23 (2) 32 (2) 38 (3) 24 (2) 40 (3) 51 (3) 50 (3) 41 (3) 48 (3) 48 (3) 1140 Ci0 HI5NaO7.3H20 In the glucopyranose ring the mean values for the C-C and C-O bond lengths are 1.527 (10) and 1.423(11)A, respectively, for molecule A, and 1.522 (5) and 1.433 (10) A, respectively, for molecule B, in agreement with the mean values 1.522 (2) and 1.426 (2)A obtained from 57 pyranose compounds (Ohanessian, Longchambon & Arene, 1978). The mean value of the endocyclic C-C-C angles is 110.1 (9) ° for molecule A and 110.0 (9) ° for molecule B, in agreement with an sp 3 hybridization of the C atoms. The angles O4-C9-C10 and C8-C9-C10 show a difference of 5.2 (13) ° and the analogous difference for molecule B is 6.8 (12) °, both values in the range 5-9 ° reported for oligosaccharides. This angular distortion is due to interactions between the substituents at C8 and C9. The glucopyranose ring adopts a 4C 1 conformation as in most D-pyranoses. In terms of ring-puckering coordinates (Cremer & Pople, 1975) the values of the amplitude-phase pair (q2,tP2) and puckering coordinate q3 for molecule A are 0.078 (9)A, --34 (8) ° and 0.588 (9) A [Q = 0.593 (9) A and 0= 7.6 (9) °] for the sequence O4-C5-C6-C7-C8-C9. The corresponding values for molecule B are q2 = 0.032 (10) A, tp2 =-49 (18) ° and q3 = 0.588 (9) A [Q = 0.589 (9) A and 0= 3.1 (10) °] for the analogous sequence. The asymmetry parameters of Nardelli (1983) are ACs(04) - 0.031 (5), ACs(C5) = 0.062 (5), ACs(C6) = 0.031 (5), AC2(O4-C9)=0.001 (4), AC2(C5-O4)= 0.004 (4), AC2(C6-C5 ) =0.004 (4) for molecule A and ACs(041)=O.O17 (5), ACs(C51)=0.027 (5), ACs(C61) = 0.011 (5), ACs(O41--C91) = 0.004 (4), AC2(C51-O41) = 0.021 (4), AC2(C61-C51) = 0.018 (4) for molecule B. The mean values of the intracyclic torsion angles are 58.5 (8) ° for molecule A and 58.4 (8) ° for molecule B [values range from 50.5 (12) to 67.9 (11) ° and from 54.4 (11) to 64.1 (11) °, respectively; the smallest value being about C6-C7 and the largest value about C9-O4 for molecule A and similarly for molecule B]. As observed generally in pyranose rings, a greater puckering occurs about the C5-O4, O4-C9 and C8-C9 bonds and a smaller puckering about C5-C6, C6-C7 and C7-C8 bonds in comparison with the torsional angle of 55 ° in cyclohexane. However, for cl0 O5 C91~i~O4 ~ C 3.~t'~li~ N2 o7(,.3 Fig. 1. A projection of molecule A with lettering. molecule B, the torsion angle about C51-C61 is slightly greater than 55 o. The torsion angles C8-C9-C10-O5 = 51.0 (13) and O4-C9-C10-O5 = -69-9 (12) ° for molecule A, and the corresponding values of 54.8(13) and -67.7 (12) ° for molecule B, indicate a gauche-gauche conformation for the exocyclic bond in both molecules. This gg conformation is not the most frequent adopted for pyranoses (gg: 37.6%; tg: 2.7%; gt: 59.5%) (Longchambon, Ohanessian, Avenel & Newman, 1975); the gauche angles differ from the ideal value of 60 ° by less than 10 °. In the barbituric moiety the mean values for the endocyclic N--C bond lengths are 1.383 (12)A for molecule A and 1.371(12) A for molecule B in agreement with those reported for barbituric acid derivatives (Craven, Vizzini & Rodrigues, 1969; Shimizu, Nishigaki, Nakai & Osaki, 1982). Table 2. Bond lengths Molecule A C1-N1 C I-N2 CI-OI C2-C3 C2-N2 C2-O2 C3-C4 C3-C5 C4-N 1 C4-O3 C5-C6 C5-O4 C6-C7 C6--N3 C7-C8 C7-O7 C8-C9 C8-O6 C9-C10 C9-O4 CI0-O5 N2-C 1-O 1 NI-CI-O1 N1--C1--N2 N2-C2-O2 C3-C2-O2 C3-C2-N2 C2-C3-C5 C2-C3-C4 C4-C3-C5 C3-C4-O3 C3-C4-N l N 1-C4-O3 C3-C5-O4 C3-C5-C6 C6-C5-O4 C5-C6-N3 C5-C6-C7 C7--C6--N3 C6-C7--O7 C6-C7-C8 C8-C7-O7 C7-C8-O6 C7-C8-C9 C9-C8-O6 C8-C9-O4 C8-C9-C l0 C 10-C9-O4 C9-CI0-O5 C l-N 1-C4 C 1-N2-C2 C5-O4-C9 (A) and angles (0) 123.6 (ll) N21--CI l--Ol I 121.5 (10) 122.3 (ll) Nll-Cll-Oll 122-9 (10) 114-l (9) Nl l-Cl l-N21 115-6 (9) 116.7 (10) N21-C21-O21 I17.9 (9) 126-1 (9) C31-C21-O21 123.8 (9) 117.2 (9) C3 I-C21-N21 118-2 (9) 118.2 (9) C21-C31-C51 119-5 (8) 120.3 (9) C21-C31-C41 118-5 (8) 121.5 (9) C41-C31-C51 121-8 (9) 125.1 (9) C31-C41-O31 124.5 (8) 118.0 (9) C31-C41-NI I 117.5 (9) 116.8 (8) N 11 -C41-031 118-0 (8) 109.2 (7) C31-C51-O41 112-2 (8) 112.6 (8) C31-C51-C61 113-8 (8) 109.4 (9) C61-C51-O41 108-6 (9) 107.8 (9) C51-C6 l-N31 I09-9 (9) 112.0 (10) C51-C61-C71 111-3 (10) 110.3 (8) C71-C61-N31 108.5 (7) 109.5 (8) C61-C71--O71 112-5 (8) 110.1 (8) C61-C71-C81 109-7 (8) 109.2 (8) C81-C71-O71 113.3 (8) 107.0 (8) C71-C81-O61 106-8 (8) 108-3 (8) C71-C81-C91 108.9 (8) 114.5 (I0) C91-C81-O61 114.3 (10) 109.2 (10) C81-C91-O41 108.9 (10) 113-1 (9) CSI-C91-CI01 115.4 (9) 107-9 (9) C l0 I-C91-O41 108.6 (8) 109.1 (10) C91-CI01-O51 111-4(10) 125.0 (9) CII-NI 1-C41 125.9 (9) 124.8 (10) CI I-N21-C21 124.2 (9) 110.3 (7) C51-O41-C91 113-1 (7) Molecule B 1.368 (16) Cl l-Nll 1.346 (15) 1.371 (15) CI l-N21 1.365 (14) 1-182 (13) C 1 l-Ol I 1.216 (12) 1.380 (16) C21--C31 1.412 (15) • 409 (13) C21-N21 1.393 (13) • 248 (14) C21-O21 1.258 (13) • 386 (14) C31-C41 1-422 (14) • 502 (12) C31-C51 1-478 (13) • 383 (12) C41--NII 1.378 (12) • 268 (14) C41--O31 1-252 (14) • 530 (19) C5 l-C61 1.520 (18) • 423 (12) C51--O41 1-433 (l l) • 514 (13) C61-C71 1.519 (12) • 500 (13) C61-N31 1-482 (12) • 528 (14) C71-C81 1.521 (13) • 417 (13) C71-O71 1.420 (17) 1.538 (19) C81-C91 1.530 (18) 1.389 (12) C81-O61 1-402 (11) 1.526 (16) C91-C101 1.490 (15) 1.423 (11) C91-O41 1.432 (10) 1.455 (14) C 101-O51 1.419 (14) M. MILLAN, C. F. CONDE, A. CONDE AND R. M/~RQUEZ 1141 However, the values of the intracyclic C-C distances [mean values of 1.383 (13) and 1.417 (14)/L respectively, for molecules A and B] are significantly shorter than those reported for barbituric acid derivatives, revealing an appreciable double-bond character. In a valence-bond description, based on the use of Pauling's formula (Pauling, 1960), the percentage of double-bond character comes to 57% and 36% respectively (C-C: 1.504, C=C: 1.334/~). On the other hand, the mean values of the bond distances O2-C2 and O3-C4 are 1.258 (14) and 1.255 (13)/~, respectively, for molecules A and B, both higher than the adopted value for C=O. The resulting percentage of double-bond character is 65% and 67%, respectively (C-O: 1.43, C=O: 1.21/~). These features are consistent with the resonance forms: o~-N--~ O O ~ N -,..~O O,,~ N ~. O ~IN~.H ~-~N~H ~L~N~H O O 0 (a) (b) (c) Table 3. Possible hydrogen bonds X-H...Y X-H X...Y H...Y LX-H...Y O9-HO91...O1 0.91 (5)/~ 2.84 (1) ,/~ 2.03 (6)/~ 148 (6) ° OI3-HO132...O14 0-89 (5) 2.81 (1) 2.02 (6) 147 (6) O13-HOI31...O31 0.90 (7) 2.73 (2) 1.89 (7) 154 (5) O14-HO141 ...03 0.96 (7) 2-80 (2) 2.00 (8) 139 (4) O14-HO142...O12 0.95 (5) 2.75 (1) 1.86 (6) 156 (6) O71 HO71---O7 0-96 (6) 2.64 (1) 1.68 (6) 175 (5) NI-HNI...O8 1.07 (6) 2.88 (1) 1.84 (6) 165 (5) O10-HO102-..O5 P 0-88(6) 2.98(I) 2.16(6) 154(5) N3-HN31---O51 * 1.09(6) 2-96 (1) 1-90 (5) 161 (5) N3-HN32...O3 P 1.11 (6) 2.77(1) 1.68(6) 163(5) O5-HO5..-OI4" 0.89 (7) 2.79 (2) 1.91 (7) 172 (5) N31-HN313...O21" I. 13 (7) 2.73 (2) 1.68 (7) 150 (5) O6-HO6...O8 "~ 1.03 (6) 2-80 (1) 1.85 (6) 153 (5) O9-HO92.-.O13 ~ 0.84 (7) 2.82 (2) 2.16 (6) 135 (6) N2-HN2...OI0 ~ 1.03 (6) 3.12 (I) 2-12 (6) 165 (5) O51-HO51 ...O10' 0-92 (6) 2.98 (1) 2.07 (6) 167 (5) O7-HO7..-O2' 0.89 (6) 2-51 (1) 1.67 (6) 157 (5) O61-HO61...O9' 0.98 (5) 2.75 (1) 1.79 (5) 165 (7) N31-HN312...O5" 1-06 (6) 2.83 (1) 1.86 (6) 149 (5) N21-HN21...O71 ~j 1.07 (6) 2.92 (1) 1-87 (6) 164 (5) N3 I-HN311..-O3 ~ 1.07 (6) 2.81 (l) 1.79 (6) 158 (5) O8-HO81...OI 1 ~ 0.93 (6) 2.91 (I) 2.01 (6) 162 (5) Ol2-HOl21..-Ol I v" 0.94 (7) 2.85 (I) 1-96 (6) 156 (6) O8-HO82...O12 ~" 1-00 (7) 2.85 (2) 1.99 (8) 142 (4) OI0-HOI01...O6 ~"~ 0.94 (6) 2.82 (I) 1.93 (6) 160 (5) O12-HO122...O71 ~"~ 0.90 (6) 2-80 (1) 1.94 (5) 159 (5) N I I-HN 1 I..-O9 ~ 1-07 (6) 3.02 (2) 2.00 (7) 158 (5) Symmetry code: none x, y, z; (i) -x+2, y+½, -z+2; (ii) -x+2, y+½, -z+ 1 ; (iii) x+l,y, z; (iv) -x+ 1,y+½, z+2; (v) -x+2,y-½, -z+2; (vi) -x+2,y-½, -z + 1; (vii) -x+ 1, y+ ½, -z + 1; (viii) x-1, y, z; (ix) -x+ 1, y-½, -z + 2. and confirm a zwitterionic structure for the compound in which the negative charge is delocalized in the system formed by the two carbonyls at C2 and C4 and the carbon atom C3 of the barbituric ring of molecule A, and the corresponding atoms of molecule B. This structure had been proposed on the basis of IR spectra showing bands associated with the +NH 3 group (~3000 and ~1600cm -1) (Galbis-P6rez, AvalosGonz/dez, Jim+nez-Requejo & Palacios-Albarr/m, 1983). "/'o6 ~ ¢~\c8 lO5..~ TM • " . * 1061 " * .~ 07~ cT~X-"---Yc91 • ClOo5 / J,, ~ ~-- " " " .~ ~ / ~o.~ 9~-F' ,s~;Y "-'-~ °~~-~ ~ o.13~..~ " Ol, "C1~/N1A " ' " " O!1 • l - 08 ~., 012 I " * • o~ 1 ,~v °l°" / I " " 09 . J~ " Io d o Fig. 2. A view of the structure along [001]. The ring adopts a small boat deformation in molecule A [Y(A/a)2=31.4, Z 2 at 95%= 7.8] and a small twist-boat deformation in molecule B [Y(A/a) 2 -- 10.0, Z 2 at 95% = 7.8]. The dihedral angle between pyranose and barbituric rings is 80.9 (3) ° for molecule A and 90.3 (3) ° for molecule B. Crystal packing Fig. 2 shows a view along [001] of the structure, stabilized by an extended three-dimensional hydrogenbonding network in which water molecules are involved. The packing of the structure consist of chains of molecules along [001]. These chains consist of a sequence of molecules A and B alternating and aligned head-to-tail, each molecule being linked to its neighbours by hydrogen bonds. The water molecules are located between these chains and involved in hydrogen bonds linking the neighbouring chains. The chains are joined together not only by the water molecules, but also by the 07HO7...O2 (-x+2, y-½, -z+2) and N21-H21...O71 (-x+2, y-½, -z+ 1) bonds to give a three-dimensional extended packing scheme. Details of the geometry of the possible hydrogen bonds are given in Table 3. Values of the H...O distance for the O-H...O bonds are in the range 1.67-2.16 A and values of the O--H...O angle agree with the statistical result (Allen, Kennard & Taylor, 1983) that short hydrogen bonds tend to be more linear than long ones. For the three bonds with O...H < 1.81 A the mean value of the donor-proton-acceptor angle is 166 (5) °, in agreement with the mean value 168.4 (9) ° reported (Allen, 1142 CIoHlsN3OT.3H20 Kennard & Taylor, 1983), but for bonds with O...H > 1.81 A the mean value found is 150 (3) °, lower than the mean value 165.8 (12) ° reported in the above-cited statistical study. For the N-H...O bonds the mean value of the H...O distance is 1.86 (5) A and the mean N-H-.-O angle is 159 (4) o. We thank Professor J. A. Galbis for supplying the crystals and for helpful discussions on chemical aspects and Professor A. L6pez Castro for collecting the diffraction data. The present work is part of a project supported by a grant of the Comisi6n Asesora de Investigaci6n Cientifica y T6cnica of the Spanish Government. References • ALLEN, F. H., KENNARD, O. & TAYLOR, R. (1983). Acc. Chem. Res. 16, 146-153. AVALOS-GONZALEZ, M. (1981). Doctoral Thesis. Univ. of Extremadura, Spain. CRAVEN, B. M., V~zrm, E. A. & RODmGUES, M. M. (1969). Acta Cryst. B25, 1978-1993. CREMER, D. & POPLE, J. A. (1975). J. Am. Chem. Soc. 97, 1354-1358. GALBIS-PI~REZ, J. A., AVALOS-GONZ.~LEZ, M., JIMI~NEZ-REQUEJO, J. L. & PALACIOS-ALBARR~,N, J. C. (1983). Carbohydr. Res. 124, C15-C17. HAMILTON, W. C. (1959). Acta Cryst. 12, 609-610. International Tables for X-ray Crystallography (1974). Voi. IV. Birmingham: Kynoch Press. (Present distributor D. Reidel, Dordrecht.) LONGCHAMBON, F., OHANESSIAN, J. AVENEL, D. & NEWMAN, A. (1975). Acta Cryst. B31, 2623-2627. MAIN, P., FISKE, S., HULL, S. E., LESSINGER, L., GERMAIN, P., DECLERCQ, J.-P. & WOOI2SON, 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. MILL~N, M., CONDE, C. F., CONDE, A. & M.~RQUEZ, R. (1985). Acta Cryst. C41, 274-277. NARDELLI, M. (1983). Acta Cryst. C39, 1141-1142. OHANESSlAN, J., LONGCHAMaON, F. & ARENE, C. (1978). Acta Cryst. B34, 3666-3671. PAULING, L. (1960). The Nature of the Chemical Bond. Ithaca: Cornell Univ. Press. SmMIZU, N., NISHIGAKI, S., NAKAI, Y. & OSAKI, K. (1982). Acta Cryst. B38, 2309-2311. STEWART, J. M., KUNDELL, F. A. & BALDWIN, J. C. (1970). The XRA YTO system. Computer Science Center, Univ. of Maryland, College Park, Maryland. Acta Cryst. (1987). C43, 1142-1145 l,l',3,3'-Tetrakis(dimethylamino)-4H,4'H-4,4'-biisoquinolyldiium Diperehlorate (II) and l,l',3,3'-Tetralds(dimethylamino)-4,4'-biisoquinolyl (III) BY PETER F. LInDLEY AND ADmAL R. WALTON Department of Crystallography, Birkbeck College, Malet St., London WC1E 7HX, England GERHARD V. BoYo AND GEORGE A. NICOLAOU Department of Chemistry, King's College London, Kensington Campus, London W8 7AH, England AND OLE HAMMERICH Department of General and Organic Chemistry, The H. C. Orsted Institute, 21 O0 Copenhagen, Denmark (Received 14 October 1986; accepted 19 January 1987) Abstract. (II): C26H34N2+.2C104, Mr= 629.5, monoclinic, I2/a, a=14.580(1), b=10.760(1), c= 18.634 (1) A, fl = 90.693 (3) °, U= 2923.1 (4)/k 3, Z =4, Dx=l.43Mgm -3, CuK~ 2=1.54178 /~, # = 2.381 mm -1, F(000) = 1320, T= 293 (1) K, R = 0-068 for 2606 unique reflections. (III): C26H32N6, Mr=428"6, monoclinic, P2j/c, a=9.844 (9), b= 10.580 (9), c = 24.355 (21) A, fl= 109.860 (8) °, U =2386(4),tt 3 , Z=4, D x=l.19Mgm -3, CuKa, ;t = 1.54178/k, a = 0.496 mm -1, F(000) = 920, T= 293 (1)K, R = 0.055 for 4056 unique reflections. The symmetry-related halves of the cation in (II) are 0108-2701/87/061142-04501.50 nearly parallel and are joined by an exceptionally long [1.597 (2)/~] bond; in the conjugate base (III)this bond is 1.496 (7)/~, the normal length for a single bond between spZ-hybridized C atoms, and the planes of the halves of the molecule form a dihedral angle of 62.8(3) ° . Introduction. The work reported herein arose from an investigation into the chemistry of the readily available 1,3-bis (dimethylamino)isoquinolines (I). Oxidative dimerization of (I) with aqueous silver perchlorate or cyclic voltammetry resulted in the formation © 1987 International Union of Crystallography