X-Ray Structure and Molecular-Packing Analysis of Artemetin

1826 C 10H14N402 S b b Fig. 3. Stereoscopic drawing of the molecular packing in the unit cell. References BOLIN, R. B., BEYER, R. P. & NEMO, G. J. (1983). Editors. Advances in Blood Substitute Research. New York: Alan R. Liss, Inc. HOSMANE, R. S. & BERTHA, C. M. (1986). Unpublished results. International Tables for X-ray Crystallography (1974). Vol. IV. Birmingham: Kynoch Press. (Present distributor D. Reidel, Dordrecht, The Netherlands.) JOHNSON, C. K. (1965). ORTEP. Report ORNL-3794. Oak Ridge National Laboratory, Tennessee, USA. McCoRMICK, J. E. & MCELHINNEY, R. S. (1972). J. Chem. Soc. Perkin Trans. 1, pp. 1335-1342. MAIN, P., HULL, S. E., LESSINGER, L., GERMAIN, G., DECLERCQ, J.-P. & WOOLFSON, M. M. (1978). MULTAN78. A System of Computer Programs for the Automatic Solution of Crystal Structures from X-ray Diffraction Data. Univs. of York, England, and Louvain, Belgium. SCHOMAKER, V. & MARSH, R. E. (1983). Acta Cryst. A39, 819-820. SHELDRICr,, G. M. (1976). SHELX76. Program for crystal structure determination. Univ. of Cambridge, England. WALDER, J. A., WALDER, R. Y. ~ ARNONE, A. (1980). J. Mol. Biol. 141, 195-216. Acta Cryst. (1987). C43, 1826-1829 X-ray Structure and Molecular-Packing Analysis of Artemetin BY M. D. ESTRADA, A. CONDE AND R. M~,RQUEZ Departamento de Fisica del Estado S6lido, Facultad de Ffsica, Universidad de Sevilla, Spain AND R. JIMI~NEZ-GARAY Departamento de Fisica, Facultad de Ciencias, Universidad de Cddiz, Spain (Received 26 March 1987; accepted 12 May 1987) f P Abstract. 5-Hydroxy-3,3,4,6,7-pentamethoxyflavone (flavone is 2-phenyl-4H-l-benzopyran-4-one), C20H20 - 08, Mr= 388-4, monoclinic, P21/n, a = 7.518 (4), b=13.625(3), c=17.766(5)A, fl=98.52(3) °, F = 1803 (1) ./k 3, Z = 4, D x = 1.430 Mg m -3, 2(Mo Ka) = 0-7107 A, /~ = 0.104 mm -I, F(000) = 816, room temperature, final wR=0.063 for 1480 observed reflexions. The benzopyran ring and the attached phenyl ring are quasi-planar. Dihedral angles between least-squares planes through each of the two rings are lower than 2 °. An intramolecular O-H...O hydrogen bond exists involving hydroxyl and carbonyl groups of the phenyl and pyrone rings. Molecular-packing analysis in the atom-atom approach yields an equilibrium configuration in very good agreement with the experimental one. Introduction. The genus Artemisia, which comprises several morphologically different sections, has received 0108-2701/87/091826-04501.50 considerable attention from the point of view of sesquiterpene lactone content but flavonoid compounds are another important class of secondary metabolites frequently isolated from Artemisia.. Some sesquiterpene lactones of the guaiane type were isolated (Gonzhlez, Bermejo, de la Rosa & MartinezMassanet, 1976) from A. lanata Willd, a perennial plant found in the calcareous hills in the south-east and east of the Iberian Peninsula. The crystal structure of one of these compounds was recently reported (Estrada, Conde, Mhrquez & Jim+nez-Garay, 1986). Continuing the phytochemical investigation of the above species, the presence of several flavonoids was revealed (Esteban, Gonzflez Collado, Macias, MartinezMassanet & Rodriguez Luis, 1986). Artemetin (I) is one of the three flavonoids isolated from the ethanolic extract of the aerial part of the plant and the X-ray structure determination was suggested to characterize unambiguously its chemical details and path reactions. © 1987 International Union of Crystallography M. D. ESTRADA, A. CONDE, R. MARQUEZ AND R. JIMI~NEZ-GARAY 1827 ~,, fOMe MeO ~ 0 ~ OMe MeO / T Y N OMe 0 MeO (I) Table 1. Atomic coordinates and equivalent isotropic thermal parameters o(1) 0(2) 0(3) 0(4) 0(5) 0(6) Experimental. Single crystals, in the form of yellow o(7) 0(8) prisms elongated along [100], obtained from the c(1) Organic Chemistry Department of the University of c(2) Chdiz. The poor quality of the crystals made the c(3) c(4) selection of a specimen for diffraction measurements c(5) difficult and limited the accuracy of intensities and c(6) C(7) consequently of the whole analysis. Crystal 0.04 x c(8) 0.03 x 0.20mm. Unit-cell parameters from 25 rec(9) flexions, 5 < 0 < 15 °. Enraf-Nonius CAD-4 diffracc(10) C(ll) tometer, graphite monochromator, 2 < 0 < 30 ° (0 < c(12) h < 8, 0 < k < 16, 0 < l < 21), o>-20-scan mode. Two c(13) standard reflexions (040, 040), variation in intensity less c(14) C(15) than 3% of the mean value. 3089 independent rec(16) flexions measured, 1609 unobserved [I < 3o(I)]. c(17) Lorentz and polarization correction, no correction for c(18) C(19) absorption or extinction. Structure solved by direct c(20) methods using MULTAN80 (Main, Fiske, Hull, Lessinger, Germain, Declercq & Woolfson, 1980). Fullmatrix least-squares refinement; ~w( I F o I -- IF cl)2 minimized with weighting scheme based on the statistical count criterion (w = l/a2). Difference Fourier synthesis revealed the 20 H-atom positions; isotropic temperature factor B --- 4-0 A 2 for the H atoms, further least-squares refinement including positional parameters of H atoms. At final convergence A/o < 0.01, R=0.104, wR-0.063, S=2.9 for 313 refined variables. Number of reflexions/number of parameters = 4.7. Max. and min. values in final difference synthesis 0.35 and -0.3 e/~ -3, respectively. Atomic scattering factors from International Tables for X-ray Crystallography (1974). Crystallographic programs of the XRAY76 system (Stewart, Machin, Dickinson, Ammon, Heck & Flack, 1976) used throughout. Discussion. Fractional atomic coordinates and equivalent isotropic temperature factors (Hamilton, 1959) for non-H atoms are listed in Table 1.* Molecular geometry An OR TEP (Johnson, 1965) drawing of the molecule with atom numbering is displayed in Fig. 1 and bond lengths and angles involving non-H atoms are listed in * Lists of structure factors, anisotropic thermal parameters and H-atom coordinates have been deposited with the British Library Document Supply Centre as Supplementary Publication No. SUP 44073 (16 pp.). Copies may be obtained through The Executive Secretary, International Union of Crystallography, 5 Abbey Square, Chester CH 1 2HU, England. Ue q = ~1-i-Jt"ijt~i\ \ 11 ..,..,ai.ajcos(ai,aj).~,j x y z Ueq(A z x -0.2418 (9) 0.4675 (5) -0.0715 (3) 42 (2) -0.2205 (8) 0.3696 (5) 0-1194 (3) 48 (2) -0.1623 (11) 0.2042 (5) 0.0368 (4) 62 (3) -0.1343 (10) 0.1233 (5) -0.0915 (4) 53 (3) -0.1666 (9) 0.1412 (5) -0.2467 (4) 47 (2) -0.2257 (9) 0.3189 (5) -0.3114 (4) 50 (3) -0.3018 (11) 0.6944 (6) 0.2149 (4) 63 (3) -0.3598 (I 1) 0.8382 (5) 0.1210 (4) 61 (3) -0.2364 (12) 0-4625 (7) 0.0068 (5) 39 (3) -0.2139 (13) 0.3759 (7) 0.0427 (5) 42 (3) -0.1849 (12) 0.2855 (7) 0.0037 (5) 39 (3) -0.1885 (13) 0.2941 (7) -0-0767 (5) 42 (3) -0.2204 (12) 0.3842 (7) -0.1121 (5) 41 (3) -0.2317 (12) 0-3973 (6) -0.1894 (5) 38 (3) -0.2142 (12) 0.3177 (7) -0.2345 (5) 40 (3) -0.1781 (12) 0.2231 (7) -0.2023 (5) 39 (3) -0.1674 (12) 0.2123 (7) -0.1247 (6) 42 (3) -0.2672 (12) 0.5606 (7) 0.0360 (5) 39 (3) -0.2694 (13) 0-5777 (7) 0.1141 (5) 44 (3) -0.2987 (13) 0.6718 (8) 0.1400 (6) 48 (4) -0.3309 (15) 0.7499 (8) 0.0882 (6) 53 (4) -0.3259(15) 0.7337(7) 0.0119(6) 51 (4) -0.2978 (14) 0.6400 (7) -0.0136 (5) 47 (3) -0.0483 (13) 0.3582 (8) 0.1663 (6) 53 (4) -0.0040 (14) 0.1339 (8) -0.2760 (7) 59 (4) -0.2823 (17) 0.4104 (8) -0.3480 (6) 61 (4) -0.2527 (16) 0.6227 (9) 0.2706 (6). 59 (4) -0.3809 (20) 0.9190 (9) 0.0705 (8) 78 (6) 103 ) Table 2. For bonds involving H atoms, C-H distances range from 1.09 (4) to 1.12 (5) A [mean value 1.10 (2) A] and the O-H distance in the phenyl group is 1.00 (5) A. The benzopyran is quasi-planar. The puckering amplitude (Cremer & Pople, 1975) of the pyrone ring is Q = 0.031 (9)A and the dihedral angle between leastsquares planes through the phenyl and pyrone rings is 2.0 (3) °. On the other hand, the phenyl least-squares plane is rotated by only 1.2 (3) ° with respect to the benzopyran least-squares plane. An intramolecular O(4)-H(O4)...O(3) hydrogen bond is clear: O(4)-H(O4)--1.01 (5), 0(4)...0(3) = 2.568 (11), H(O4)...O(3) --- 1.63 (5) A, 0(4)- H(O4)...O(3) = 153 (5) °. Apart from this interaction other intramolecular C-H...O contacts could also be considered as hydrogen bonds if the criteria H...O distance less than 2.40/~, and C-H..-O angle larger than 90 ° (Taylor & Kennard, 1982) are used. These contacts are C(11)-H(11)...O(2) and C(15)-H(15)... O(1). Molecular-packing analysis Fig. 2. shows the contents of the unit cell viewed down [100]. The crystal cohesion is mainly due to van der Waals forces. Only the C(16)-H(162)...O(6)- (x + ½, -y + ½, z + ½) interaction linking molecules related by the glide plane may be considered as a possible hydrogen bond. Details of the geometry of this contact are: C(16)-H(162)= 1.10 (5), C(16)...O(6) 1828 ARTEMETIN = 3.41 (1), H(162)...O(6) = 2.45 (4) A, C(16)- H(162)...O(6)= 145 (4) °. As observed, the C...O distance of this contact is higher than the sum of the van der Waals radii (3.25 A) but the H...O distance and the C-H...O angle satisfy the criteria of Taylor & Kennard (1982) for hydrogen bonds. No other intermolecular contacts significantly shorter than the sum of the van der Waals radii have been detected. The molecular geometry and crystal packing were computed by PARST (Nardelli, 1983). Lattice-energy calculations in the atom-atom potential approach were performed using the computer C19 Cl6 02 0.0.3 0 7 ~ ~I 0~~2 0~3 ~ 0 ~ C,2 C'~ 0 ' C9 0 d2o 206 bC18 Fig. 1. An OR TEP plot of the molecule with atom labelling, ellipsoids at 0.5 probability level. Table 2. Bond distances (A) and angles (o) O(l)-C(1) 1.386 (l 1) 0(2)-C(2) 1.373 (1 I) 0(3)-C(3) 1.256 (12) O(5)-C(8) 1.379 (11) O(6)-C(7) 1.357 (11) O(7)--C(12) 1.370 (12) O(8)-C(13) 1.371 (13) C(1)-C(2) 1.342 (13) C(2)-C(3) 1.448 (14) C0)-C(5) 1.386 (13) C(5)-C(6) 1.374 (13) C(7)-C(8) 1.422 (13) C(IO)-C(I 1) 1.409 (13) C(11)-C(12) 1.392 (15) C(13)-C(14) 1.379 (15) C(1)--O(1)--C(5) 119.9 (7) C(8)---O(5)--C(17) 113.7 (7) C(12)-O(7)-C(19) 119.2 (8) O(1)--C(1)--C(IO) 109-1 (7) C(2)-C(1)-C(10) 130.6 (9) C(1)-C(2)-C(3) 122.6 (9) O(3)-C(3)--C(2) 123.3 (9) O(3)-C(3)-C(4) 121.4 (9) C(3)-C(4)-C(5) 120-2 (9) O(1)-C(5)---C(4) 121.5 (8) O(1)--C(5)---C(6) 115.1 (8) O(6)--C(7)-C(6) 125.7 (8) O(6)-C(7)--C(8) 113.3 (8) C(7)-C(8)-C(9) 118.7 (8) C(4)-C(9)-C(8) 121.2 (8) O(4)-C(9)-C(4) 118.1 (8) C(I)--C(10)-C(11) 121.7 (8) C(10)-C(ll)-C(12) 120.3 (9) C(11)-C(12)-C(13) 120.2(9) O(8)--C(13)-C(12) 114.3 (9) O(8)-C(13)-C(14) 125.9 (9) C(10)-C(15)-C(14) 122.1(9) O(1)-C(5) 1.369 (12) O(2)-C(16) 1.440 (11) O(4)-C(9) 1.357 (11) O(5)-C(17) 1.402 (13) O(6)-C(18) 1.443 (13) O(7)--C(19) 1.402 (13) O(8)-C(20) 1.415 (15) C(1)---C(10) 1.467 (13) C(3)--C(4) 1.429 (13) C(4)-C(9) 1.428 (14) C(6)--C(7) 1.368 (13) C(8)-C(9) 1.377 (13) C(10)-C(15) 1.395 (13) C(12)-C(13) 1.406 (15) C(14)-C(15) 1.384 (14) C(2)-O(2)-C(16) 114.7 (7) C(7)-O(6)-C(18) 115.7 (8) C(13)-O(8)-C(20) 115.2 (9) O(1)-C(1)-C(2) 120.3 (8) O(2)-C(2)-C(1) 120.5 (8) O(2)-C(2)-C(3) 116.8 (8) C(2)-C(3)-C(4) 115.3 (8) C(3)-C(4)-C(9) 123.0 (9) C(5)-C(4)-C(9) 116.7 (9) C(4)-C(5)-C(6) 123.3 (9) C(5)-C(6)-C(7) 119.0 (9) C(6)-C(7)-C(8) 121.0 (8) O(5)-C(8)--C(7) 122.0 (8) O(5)-C(8)-C(9) 119.1 (8) O(4)--C(9)-C(8) 120.7 (8) C(1)-C(10)-C(15) 120.4 (8) C(I1)--C(10)-C(15) 117.9 (9) O(7)-C(12)-C(11) 12'3.7 (9) O(7)-C(12)-C(13) 116.0 (9) C(12)-C(13)-C(14) 119.7 (9) C(13)-C(14)-C(15) 119.8 (9) program PCK6 (Williams, 1972). In this program the intermolecular lattice energy of a crystal is approximated by pairwise interactions between non-bonded atoms using a form ~0 = -Ar -6 + B exp(-Cr) + K qq'/r for the potential function describing the interaction between an atom_ pair. The theoretical model assgmes that the molecules are rigid but-interrVaI •rotations around bonds (subrotations) can be relaxed. In this case additional intramolecular terms for the subrotation conjugation potentials are taken as E c = E ° cos 2 tp. The set of potential parameters to represent inter' actions between electrically neutral atoms included coefficients fitted by Mirskaya (1976) for the C and H atoms and by Mason & Kreevoy (1955) for O.-.O. For mixed interactions the arithmetic-mean-combining rule for the equilibrium interatomic distance, r o, and the geometric-mean rule for the interaction energy at a distance r = r o (Mirskaya, 1973) were used. For the calculations including the electrostatic contribution to the non-bonded-atom interactions the partial effective charge at an atom was estimated from the percentage of covalent character of bonds involving that atom (Skorczyck, 1976). Lattice-energy minimization was performed with respect to the cell constants, molecular translation and rotation and also subrotation of molecular fragments about the phenyl-pyrone bond, starting from the experimental structure. c sinB Fig. 2. A view of the unit-cell contents down [100]. Table 3. Molecular-packing-analysis results Shift of centre of mass I Arcl in A, overall molecular rotation (0) and subrotation (~0) in o and cell parameters and volume in %. I Arcl 0 Aa Ab Ac Aft A V ~o exp(-6) (a) 0.02 2.5 (b) 0.01 2.2 0.44 0.47 0.26 -0.95 1.40 -0.32 exp(-6--1) (a) 0.01 2.1 (b) 0.00 1.0 0.03 0.04 0.02 -0.32 0.15 -0.04 (a) With cell parameters and torsion fixed at experimental values; (b) with cell parameters and torsion relaxed. M. D. ESTRADA, A. CONDE, R. M/~RQUEZ AND R. JIMI~NEZ-GARAY 1829 Representative results of the energy minimization are given in Table 3. As observed, the calculated equilibrium configuration is in good agreement with the experimental structure. Considering the molecular parameters the optimized structure remains very similar to the experimental one, as shown in Table 3: the shifts of the positoinal and orientational molecular parameters are lower than 0.02 A and 2.5 °, respectively, and the torsion angle of the intramolecular relaxed rotation is reproduced within 0.3 ° . The agreement is improved when the electrostatic interaction is considered, in spite of the method used in estimating the residual charges. The expansion of the cell volume (1.4%) is also reduced (0.15%) when the electrostatic term is included in the calculations. The authors thank Professor G. Martinez-Massanet and Dr Macias Dominguez (University of C/ldiz) for supplying the crystals and for helpful discussions on chemical aspects and Professsor A. L6pez-Castro for collecting the diffractometer data. References CREMER, D. ~ POPLE, J. A. (1975). J. Am. Chem. Soe. 97, 1354-1358. ESTEBAN, M. D., GONZ.~LEZ COLLADO, I., MACiAS, F. A., MARTiNEZ-MASSANET, G. & RODRiGUEZ LUIS, F. (1986). Phytochemistry, 25(6), 1502-1504. ESTRADA, M. D., CONDE, A., M,~RQUEZ, R. t~, JIMI~NEZ-GARAY, R. (1986).Acta Cryst. C42, 1413-1415. GONZ.k.LEZ, A. G., BERMEJO, J., DE LA ROSA, A. D. & MARTiNEZMASSANET, G. (1976). An Qu:m. 72, 695-697. HAMILTON, W. C. (1959). Acta Cryst. 12, 609-610. 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, USA. 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. MASON, A. & KREEVOY, M. M. (1955). J. Am. Chem. Soc. 77, 5808-5814. MIRSKAYA, K. V. (1973). Tetrahedron, 29, 679-682. MIRSKAYA, K. V. (1976). Acta Cryst. A32, 199-207. NARDPLLI, M. (1983). Comput. Chem. 7, 95-98. 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 XRA Y76 system. Tech. Rep. TR-446. Computer Science Center, Univ. of Maryland, College Park, Maryland, USA. TAYLOR, R. & KENNARD, O. (1982). d. Am. Chem. Soc. 104, 5063-5070. WILLIAMS, D. E. (1972). Acta Cryst. A28, 629-635. SHORT-FORMAT PAPERS Contributions intended for publication under this heading should follow the format given in the Checklist for Authors [Acta Cryst. (1985). C41, 1--4]. Acta Cryst. (1987). C43, 1829-1830 Phosphate Hydrog6nophosphate Hydrate de Mangan6se PAR Y. GERAULT, A. RIOU ET Y. CUDENNEC Laboratoire de Chimie des Matdriaux Inorganiques et de Cristallographie, 20 avenue des Buttes de Cob'sines, 35043 Rennes CEDEX, France (Regu le 8 ddcembre 1986, acceptd le 10 avril 1987) Abstract. Mn5(HPO4)2(PO4)2.4H20 , M, = 728.6, monoclinic, C2/c, a= 17.587 (4), b=9.127 (3), c =9-497(5)A, fl=96.68(3) °, V=1514 (1) :k 3, D m =3.19(1), Dx=3.19Mgm -3, Z=4, MoKt~, 2--- 0.71069/~, /2=4.47mm -~, F(000)= 1420, T= 130 K, R -- 0.023 for 1581 reflexions. The structure is isotypic with hureaulite. Apart from alkaline-earth metals which are often found in weak concentrations in natural minerals, it appears that compounds of general 0108-2701/87/091829-02501.50 formula (Mn~_ x Fex)s(HPO4)2(PO4)2.4H20 probably exist for all x in the range 0-1. Pattie exp6rimentale. Une &ude r6cente de phosphates de m~taux divalents (Cudennec, Riou & Gerault, 1986) a permis, entre autre, la pr6paration du compos~ Mns(HPO4)2(PO4)2.4H20. Les monocristaux obtenus se pr6sentent sous la forme d'aiguilles pratiquement incolores. Les param&res cristallins ont © 1987 International Union of Crystallography