organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoSTRUCTURAL
CHEMISTRY
ISSN: 2053-2296

Hydantoin and hydrogen-bonding patterns in hydantoin derivatives

aAston Pharmacy School, Aston Triangle, Birmingham B4 7ET, England, and bChemical Crystallography Laboratory, 9 Parks Road, Oxford OX1 3PD, England
*Correspondence e-mail: c.h.schwalbe@aston.ac.uk

(Received 21 June 2004; accepted 19 July 2004; online 4 September 2004)

The structure of hydantoin (imidazolidine-2,4-dione), C3H4N2O2, has been determined from a twinned crystal. The two carbonyl bond lengths are nearly equal, even though one of them adjoins electron-donating NH groups to either side while the other is adjacent to only one. Ab initio molecular-orbital calculations yield more negative Löwdin charge on the former than the latter. Hydantoin mol­ecules form two chains linked by N—H⋯O hydrogen bonds, from which inversion centres create a `chain of rings'. Out of 50 hydantoin moieties in 49 independent mol­ecules of hydantoin derivatives in the Cambridge Structural Database [Version 5.25; Allen (2002[Allen, F. H. (2002). Acta Cryst. B58, 380-388.]). Acta Cryst. B58, 380–388], five show this arrangement, six are a variant using the same O atom twice, five form a chain of edge-fused 12-membered hydrogen-bonded rings, and all but three of the remainder have one eight-membered ring and/or one chain connecting their hydantoin rings.

Comment

Hydantoin, (I[link]), is of interest as the parent compound of the anti-epileptic drug di­phenyl­hydantoin and as a supramolecular synthon in its own right. Possessing equal numbers of hydrogen-bond donor (two ring NH) groups and acceptor (two carbonyl O) atoms, it can form intricate networks, but with a different presentation of these groups compared with the six-membered rings so often studied. Probably due to the difficulties with twinning described below, no structure of hydantoin has appeared in the literature to date.

[Scheme 1]

A view of (I[link]) with the atom-numbering scheme is shown in Fig. 1[link]. Electron donation from the ring N atoms to the carbonyl groups, as in resonance structures (Ia[link])–(Ic[link]), would be expected to lengthen the C=O bonds and shorten the ring C—N bonds, C2=O2 being affected from both sides. The experimental bond distances (Table 1[link]) show no significant differences between the two carbonyl bond lengths or between N1—C2 and N3—C4, but C2—N3 is longer than their average by 0.024 Å (6σ). Thus, resonance structure (Ib[link]) appears to be of limited importance. Both carbonyl groups are bent towards atom N3; the angle O2—C2—N1 exceeds O2—C2—N3 by 3.8 (3)° and the angle O4—C4—C5 exceeds O4—C4—N3 by 2.6 (3)°.

A search group was defined, consisting of a hydantoin ring with both NH groups unsubstituted and sp3 hybridization at C5. With disorder, errors or ions excluded and R < 0.1 required, a search (Bruno et al., 2002[Bruno, I. J., Cole, J. C., Edgington, P. R., Kessler, M., Macrae, C. F., McCabe, P., Pearson, J. & Taylor, R. (2002). Acta Cryst. B58, 389-397.]) of the Cambridge Structural Database (CSD, Version 5.25; Allen, 2002[Allen, F. H. (2002). Acta Cryst. B58, 380-388.]) yielded 41 hits with 50 hydantoin rings in 49 independent mol­ecules after removal of duplicate structure determinations. Mean values of the relevant bond distances, with standard error of the mean in parentheses, confirm the tendency in hydantoin: C2—O2 = 1.221 (1) Å, C4—O4 = 1.211 (1) Å, N1—C2 = 1.342 (2) Å, C2—N3 = 1.393 (2) Å and N3—C4 = 1.362 (1) Å. Bending of one carbonyl bond is common. The mean O2—C2—N1 angle is 127.9 (1)°, compared with 124.5 (1)° for O2—C2—N3, but the other C=O bond lies close to the exterior bisector, mean values being 126.8 (1)° for O4—C4—N3 and 126.3 (1)° for O4—C4—C5.

Ab initio molecular-orbital optimization of hydantoin with GAMESS (Schmidt et al., 1990[Schmidt, M. W., Baldridge, K. K., Boatz, J. A., Jensen, J. H., Koseki, S., Gordon, M. S., Nguyen, K. A., Windus, T. L. & Elbert, S. T. (1990). QCPE Bull. 10, 52-54.]) in the 6-31G* basis set corroborates the near equality of C=O distances and yields N1—C2, C2—N3 and N3—C4 distances of 1.356, 1.391 and 1.367 Å, respectively. Atomic charges were calculated by the method of Löwdin (1950[Löwdin, P. O. (1950). J. Chem. Phys. 18, 365-370.]), chosen because it is based on orthogonalized orbitals and appears to be consistent with electronegativity. Values of −0.350 on atom N1, −0.382 on O2, −0.275 on N3 and −0.348 on O4 suggest that more negative charge is received by O2 than O4, and more given up by N3 than by N1.

As seen in Fig. 2[link], each mol­ecule of (I[link]) participates in N—H⋯O hydrogen bonds (Table 2[link]), forming a chain of centrosymmetric rings with graph set C22(9) [R22(8)] [R22(8)] (Etter, 1990[Etter, M. C. (1990). Acc. Chem. Res. 23, 120-126.]; Bernstein et al., 1995[Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555-1573.]). Of the 50 independent hydantoin rings found in the search of the CSD, this (pseudo-)­cen­trosymmetric `chain of rings' arrangement occurred in five (Table 3[link]; the atom-numbering scheme has always been made to agree with the IUPAC system used in the present study), while another six exhibited a variant form in which the more electron-dense atom O2 simultaneously accepts N1—H1⋯O2 and N3—H3⋯O2 hydrogen bonds, while atom O4 accepts none (Table 4[link]).

Chains are also possible. Hydantoins can create an infinite chain in graph set C(5) with atom N1 as donor and atom O4 as acceptor, simultaneously with another C(4) motif having atom N3 as donor and atom O2 as acceptor, thereby creating edge-fused R33(12) rings. This network had five occurrences, always in a non-centrosymmetric space group (Table 5[link]).

[Scheme 2]

Many hydantoin derivatives carry polar substituents on the 5-position, which divert some or all of the hydrogen bonding away from the ring. Thus, 21 mol­ecules participate in a single R22(8) motif, 11 involving atom N1 as donor and atom O2 as acceptor, seven with N3 and O2, two with N3 and O4, and one with heterogeneous involvement of N1 with O4 and N3 with O2 (Table 6[link]). Single chains also occur frequently, two C(4) using atoms N1 and O2, five C(5) with N1 and O4, four C(4) with N3 and O2 but none with N3 and O4, and one with heterogeneous chains (Table 7[link]). Finally, three rings only interact with side groups (Table 8[link]). (The total exceeds 50 because two mol­ecules forming one ring and one chain are double-counted.) Of the potential hydrogen-bond donors and acceptors, atom N1 is left unused only three times, O2 just once and N3 not at all, but the less highly charged and less accessible atom O4 is unused 24 times. Thus, hydantoin is a versatile supramolecular synthon providing a challenge to attempts at a priori prediction.

[Figure 1]
Figure 1
A view of the structure of (I[link]), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
[Figure 2]
Figure 2
A view of two chains of (I[link]) extending through the unit cell, with atom N1 of four representative mol­ecules bearing a label. The symmetry codes are: (ii) 1 − x, −y, 1 − z; (iii) [{1 \over 2}] + x, [{1 \over 2}] + y, z; (iv) [{3 \over 2}] − x, [{1 \over 2}] − y, 1 − z. Other mol­ecules are generated from these by adding 1 to both x and z or subtracting 1 from both x and z. Hydro­gen bonds are shown as dashed lines.

Experimental

Crystals of (I[link]), in habits ranging from stubby needles to tabular blocks, were grown by slowly cooling to room temperature a saturated aqueous solution prepared at 353 K. An attempt to obtain a more tractable crystal form by diffusing acetic acid vapour into a sample of hydantoin in 12.5% sodium hydroxide solution yielded a conglomerate of sticky needles showing the same unit cell, space group and propensity to form twins.

Crystal data
  • C3H4N2O2

  • Mr = 100.08

  • Monoclinic, C2/c

  • a = 9.3538 (7) Å

  • b = 12.1757 (11) Å

  • c = 7.2286 (6) Å

  • β = 104.593 (4)°

  • V = 796.70 (11) Å3

  • Z = 8

  • Dx = 1.669 Mg m−3

  • Mo Kα radiation

  • Cell parameters from 730 reflections

  • θ = 5–27°

  • μ = 0.14 mm−1

  • T = 190 K

  • Plate, colourless

  • 0.18 × 0.10 × 0.02 mm

Data collection
  • Nonius KappaCCD area-detector diffractometer

  • ω scans

  • Absorption correction: multi-scan (DENZO and SCALEPACK; Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.]) Tmin = 0.99, Tmax = 1.00

  • 1593 measured reflections

  • 886 independent reflections

  • 886 reflections with I > −10σ(I)

  • Rint = 0.02

  • θmax = 27.4°

  • h = −12 → 12

  • k = −14 → 15

  • l = −9 → 9

Refinement
  • Refinement on F2

  • R(F) = 0.061

  • wR(F2) = 0.131

  • S = 1.13

  • 886 reflections

  • 77 parameters

  • Only coordinates of H atoms refined

  • w = 1/[σ2(F*) + 1.89P] where P = [{1 \over 3}]max(Fo2,0) + [{2 \over 3}]Fc2

  • (Δ/σ)max < 0.001

  • Δρmax = 0.27 e Å−3

  • Δρmin = −0.25 e Å−3

Table 1
Selected geometric parameters (Å, °)

C2—O2 1.222 (3) 
C2—N1 1.371 (3)
C2—N3 1.393 (3)
N3—C4 1.367 (3)
C4—O4 1.225 (3)
C4—C5 1.460 (3)
C5—N1 1.457 (3)
O2—C2—N1 128.2 (2)
O2—C2—N3 124.4 (2)
N3—C2—N1 107.4 (2)
C4—N3—C2 111.67 (19)
O4—C4—C5 127.9 (2)
O4—C4—N3 125.3 (2)
C5—C4—N3 106.8 (2)
N1—C5—C4 104.7 (2)
C2—N1—C5 109.4 (2)

Table 2
Hydrogen-bonding geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N1—H1⋯O2i 0.95 (3) 2.01 (3) 2.913 (3) 158
N3—H3⋯O4ii 0.87 (4) 1.98 (4) 2.852 (3) 176
Symmetry codes: (i) 2-x,-y,2-z; (ii) 1-x,-y,1-z.

Table 3
Hydantoin derivatives in the CSD forming the same C22(9) [R22(8)] [R22(8)] network as hydantoin or a comparable network with a pseudo-centre of inversion

Refcode Space group D—H⋯A Reference
BCOCHY C2/m N1—H⋯O2 Smith-Verdier et al. (1979a[Smith-Verdier, P., Florencio, F. & García-Blanco, S. (1979a). Acta Cryst. B35, 216-217.])
    N3—H⋯O4  
GRNSHY, mol 1 P[\overline 1] N1—H⋯O2′′ Florencio et al. (1980[Florencio, F., Smith-Verdier, P. & García-Blanco, S. (1980). Cryst. Struct. Commun. 9, 687-692.])
    N3—H⋯O4′′  
GRNSHY, mol 2 P[\overline 1] N1—H′′⋯O2  
    N3—H′′⋯O4  
OCSHYD C2/c N1—H⋯O2 Miller & McPhail (1979[Miller, R. W. & McPhail, A. T. (1979). J. Chem. Res. pp. 330-331.])
    N3—H⋯O4  
VARBAR P21/c N1—H⋯O2 Rizzi et al. (1989[Rizzi, J. P., Schnur, R. C., Hutson, N. J., Kraus, K. G. & Kelbaugh, P. R. (1989). J. Med. Chem. 32, 1208-1213.])
    N3—H⋯O4  

Table 4
Hydantoin derivatives forming a C11(4) C11(4) [R22(8)] network based on N1—H⋯O2 and N3—H⋯O2 hydrogen bonds with O4 not used

Refcode Space group D—H⋯A Reference
ADUQOF P212121 N1—H⋯O2 Beilles et al. (2001[Beilles, S., Cardinael, P., Ndzie, E., Petit, S. & Coquerel, G. (2001). Chem. Eng. Sci. 56, 2281-2294.])
    N3—H⋯O2  
BEPNIT P212121 N1—H⋯O2 Cassady & Hawkinson (1982[Cassady, R. E. & Hawkinson, S. W. (1982). Acta Cryst. B38, 1646-1647.])
    N3—H⋯O2  
HPHCMS P21 N1—H⋯O2 Koch et al. (1975[Koch, M. H. J., Germain, G., Declercq, J. P. & Dusausoy, Y. (1975). Acta Cryst. B31, 2547-2549.])
    N3—H⋯O4  
OGUVIV P21 N1—H⋯O2 Stalker et al. (2002[Stalker, R. A., Munsch,, T. E., Tran, J. D., Nie, X., Warmuth, R., Beatty, A. & Aakeroy, C. B. (2002). Tetrahedron, 58, 4837-4849.])
    N3—H⋯O4  
XERTUJ, mol 1 P21 N1—H⋯O2′′ Koos et al. (2000[Koos, M., Steiner, B., Langer, V., Gyepesova, D. & Durik, M. (2000). Carbohydr. Res. 328, 115-126.])
    N3—H⋯O2′′  
XERTUJ, mol 2 P21 N1—H′′⋯O2  
    N3—H′′⋯O2  

Table 5
Hydantoin derivatives forming a chain of edge-fused R33(12) rings

Refcode Space group D—H⋯A Reference
DAFFIZ01 P212121 N1—H⋯O4 Sarges et al. (1985[Sarges, R., Bordner, J., Dominy, B. W., Peterson, M. J. & Whipple, E. B. (1985). J. Med. Chem. 28, 1716-1720.])
    N3—H⋯O2  
LABTIR P212121 N1—H⋯O4 Coquerel et al. (1993[Coquerel, G., Petit, M. N. & Robert, F. (1993). Acta Cryst. C49, 824-825.])
    N3—H⋯O2  
PHYDAN Pn21a N1—H⋯O4 Camerman & Camerman (1971[Camerman, A. & Camerman, N. (1971). Acta Cryst. B27, 2205-2211.])
    N3—H⋯O2  
PIPVAL P21 N1—H⋯O4 Modric et al. (1993[Modric, N., Poje, M., Watkin, D. J. & Edwards, A. J. (1993). Tetrahedron Lett. 34, 4679-4682.])
    N3—H⋯O2  
YECDOZ P212121 N1—H⋯O4 Park et al. (1994[Park, H.-G., Vela, M. A. & Kohn, H. (1994). J. Am. Chem. Soc. 116, 471-478.])
    N3—H⋯O2  

Table 6
Hydantoin derivatives forming a single R22(8) motif

Refcode Space group D—H⋯A Reference
BICSIP P21/n N1—H⋯O2 Florencio et al. (1982[Florencio, F., Smith-Verdier, P. & García-Blanco, S. (1982). Acta Cryst. B38, 2089-2091.])
CECKUQ P[\overline 1] N1—H⋯O2 Galvez et al. (1983[Galvez, E., Martinez, M., Gonzalez, J., Trigo, G. G., Smith-Verdier, P., Florencio, F. & García-Blanco, S. (1983). J. Pharm. Sci. 72, 881-886.])
DPHEAD20, mol 1 P[\overline 1] N1—H⋯O2 Mastropaolo et al. (1983[Mastropaolo, D., Camerman, A. & Camerman, N. (1983). Mol. Pharmacol. 23, 273-277.])
EZOSHY P21/c N1—H⋯O2 Smith-Verdier et al. (1979b[Smith-Verdier, P., Florencio, F. & García-Blanco, S. (1979b). Acta Cryst. B35, 1911-1913.])
MANHDT10 P21/n N1—H⋯O2 Vilches et al. (1981[Vilches, J., Florencio, F., Smith-Verdier, P. & García-Blanco, S. (1981). Acta Cryst. B37, 201-204.])
MESYIS, mol 1 P1 N1—H⋯O2′′ Koos et al. (2001[Koos, M., Steiner, B., Micova, J., Langer, V., Durik, M. & Gyepesova, D. (2001). Carbohydr. Res. 332, 351-361.])
MESYIS, mol 2 P1 N1—H′′⋯O2  
MGSHYD10, mol 1 P21 N1—H⋯O2′′ Florencio et al. (1978a[Florencio, F., Smith-Verdier, P. & García-Blanco, S. (1978a). Acta Cryst. B34, 1317-1321.])
MGSHYD10, mol 2 P21 N1—H′′⋯O2  
MZBSHY P21/n N1—H⋯O2 Florencio et al. (1979[Florencio, F., Smith-Verdier, P. & García-Blanco, S. (1979). Acta Cryst. B35, 2422-2424.])
TRSHYD10 P21/c N1—H⋯O2 Smith-Verdier et al. (1977[Smith-Verdier, P., Florencio, F. & García-Blanco, S. (1977). Acta Cryst. B33, 3381-3385.])
ALATIN01 P21/c N3—H⋯O2 Zhang et al. (1992[Zhang, J., Zhang, Z., You, K. & Fan, Y. (1992). Jilin Daxue Ziran Kexue Xuebao (Acta Sci. Nat. Univ. Jilin), pp. 87-89. (In Chinese.)])
DPHEAD20, mol 2 P[\overline 1] N3—H⋯O2 Mastropaolo et al. (1983[Mastropaolo, D., Camerman, A. & Camerman, N. (1983). Mol. Pharmacol. 23, 273-277.])
DPHPZL P[\overline 1] N3—H⋯O2 Uno & Shimizu (1980[Uno, T. & Shimizu, N. (1980). Acta Cryst. B36, 2794-2796.])
HEGRAH P21/c N3—H⋯O2 Florencio et al. (1978b[Florencio, F., Smith-Verdier, P. & García-Blanco, S. (1978b). Acta Cryst. B34, 2220-2223.])
VAPZUH P21/c N3—H⋯O2 Rizzi et al. (1989[Rizzi, J. P., Schnur, R. C., Hutson, N. J., Kraus, K. G. & Kelbaugh, P. R. (1989). J. Med. Chem. 32, 1208-1213.])
XERTOD, mol 1 P43 N3—H⋯O2′′ Koos et al. (2000[Koos, M., Steiner, B., Langer, V., Gyepesova, D. & Durik, M. (2000). Carbohydr. Res. 328, 115-126.])
XERTOD, mol 2 P43 N3—H′′⋯O2  
AHINEK P21/c N3—H⋯O4 SethuSankar et al. (2002[SethuSankar, K., Thennarasu, S., Velmurugan, D. & Kim, M. J. (2002). Acta Cryst. C58, o715-o717.])
NIVZOH P21/c N3—H⋯O4 Benedetti et al. (1997[Benedetti, E., DiBlasio, B., Iacovino, R., Menchize, V., Saviano, M., Pedone, C., Bonora, G. M., Ettorre, A., Graci, L., Formaggio, F., Crisma, M., Valle, G. & Toniolo, C. (1997). J. Chem. Soc. Perkin Trans. 2, pp. 2023-2032.])
COQQEE P21 N1—H⋯O4′′ Mullica et al. (1998[Mullica, D. F., Trawick, M. L., Wu, P. W. N. & Sappenfield, E. L. (1998). J. Chem. Crystallogr. 28, 761-765.])
    N3—H′′⋯O2  
†Although Z′ = 1, the mol­ecule has an independent hydantoin ring at each end.

Table 7
Hydantoin derivatives forming a single chain motif

Refcode Space group D—H⋯A Reference
NIVZOH P21/c N1—H⋯O2 Benedetti et al. (1997[Benedetti, E., DiBlasio, B., Iacovino, R., Menchize, V., Saviano, M., Pedone, C., Bonora, G. M., Ettorre, A., Graci, L., Formaggio, F., Crisma, M., Valle, G. & Toniolo, C. (1997). J. Chem. Soc. Perkin Trans. 2, pp. 2023-2032.])
TOTPIB P21 N1—H⋯O2 Bravo et al. (1996[Bravo, P., Capelli, S., Meille, S. V., Seresini, P., Volonterio, A. & Zanda, M. (1996). Tetrahedron: Asymmetry, 7, 2321-2332.])
BAGXOW P21/c N1—H⋯O4 Terzis et al. (1981[Terzis, A., Filippakis, S. E. & Mentzafos, D. (1981). Cryst. Struct. Commun. 10, 803-806.])
HOIMCU, mol 1 P21/n N1—H⋯O4 Poje et al. (1980[Poje, M., Paulus, E. F. & Rocic, B. (1980). J. Org. Chem. 45, 65-68.])
ROKSOZ Pna21 N1—H⋯O4 Gauthier et al. (1997[Gauthier, T. J., Yokum, T. S., Morales, G. A., McLaughlin, M. L., Liu, Y.-H. & Fronczek, F. R. (1997). Acta Cryst. C53, 1659-1661.])
SINZEU P212121 N1—H⋯O4 Galdecki & Karolak-Wojciechowska (1986[Galdecki, Z. & Karolak-Wojciechowska, J. (1986). J. Crystallogr. Spectrosc. Res. 16, 467-474.])
VAPZUH P21/c N1—H⋯O4 Rizzi et al. (1989[Rizzi, J. P., Schnur, R. C., Hutson, N. J., Kraus, K. G. & Kelbaugh, P. R. (1989). J. Med. Chem. 32, 1208-1213.])
GODRAS P212121 N3—H⋯O2 Eknoian et al. (1999[Eknoian, M. W., Webb, T. R., Worley, S. D., Braswell, A. & Hadley, J. (1999). Acta Cryst. C55, 405-407.])
GOPZIU, mol 1 P21 N3—H⋯O2′′ Agasimundin et al. (1998[Agasimundin, Y. S., Mumper, M. W. & Hosmane, R. S. (1998). Bioorg. Med. Chem. 6, 911-923.])
GOPZIU, mol 2 P21 N3—H′′⋯O2  
ROKSUF P21/c N3—H⋯O2 Gauthier et al. (1997[Gauthier, T. J., Yokum, T. S., Morales, G. A., McLaughlin, M. L., Liu, Y.-H. & Fronczek, F. R. (1997). Acta Cryst. C53, 1659-1661.])
COQQEE P21 N3—H⋯O2′′ Mullica et al. (1998[Mullica, D. F., Trawick, M. L., Wu, P. W. N. & Sappenfield, E. L. (1998). J. Chem. Crystallogr. 28, 761-765.])
    N1—H′′⋯O4  
‡Although Z′ = 1, the mol­ecule has an independent hydantoin ring at each end.

Table 8
Hydantoin derivatives without ring-to-ring hydrogen bonding

Refcode Space group D—H⋯A Reference
HOIMCU, mol 2 P21/n None Poje et al. (1980[Poje, M., Paulus, E. F. & Rocic, B. (1980). J. Org. Chem. 45, 65-68.])
JOPPAF P21 None Yamagishi et al. (1992[Yamagishi, M., Yamada, Y., Ozaki, K., Da-te, T., Okamura, K., Suzuki, M. & Matsumoto, K. (1992). J. Org. Chem. 57, 1568-1571.])
QIBNIY P21/c None SethuSankar et al. (2001[SethuSankar, K., Thennarasu, S., Velmurugan, D., Shanmuga Sundara Raj, S., Fun, H.-K. & Perumal, P. T. (2001). Acta Cryst. E57, o377-o379.])

H-atom positions were refined freely, and Uiso(H) values were set initially to 1.2Ueq(C,N) and not refined further. The data were refined as a two-component twin, (1 0 0, 0 1 0, 0 0 1) and (1 0 0.652, 0 [\overline 1] 0, 0 0 [\overline 1]), with twin element scale factors of 0.869 (6) and 0.131 (6).

Data collection: COLLECT (Nonius, 1998[Nonius (1998). COLLECT. Nonius BV, Delft, The Netherlands.]); cell refinement: DENZO and SCALEPACK (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.]); data reduction: DENZO and SCALEPACK; program(s) used to solve structure: SIR92 (Altomare et al., 1994[Altomare, A., Cascarano, G., Giacovazzo, C., Guagliardi, A., Burla, M. C., Polidori, G. & Camalli, M. (1994). J. Appl. Cryst. 27, 435.]) and SHELXL97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXL97. University of Göttingen, Germany.]); program(s) used to refine structure: CRYSTALS (Watkin et al., 1999[Watkin, D. J., Prout, C. K., Carruthers, J. R. & Betteridge, P. W. (1999). CRYSTALS. Issue 11. Chemical Crystallography Laboratory, Oxford, England.]); molecular graphics: CAMERON (Watkin et al., 1996[Watkin, D. J., Prout, C. K. & Pearce, L. J. (1996). CAMERON. Chemical Crystallography Laboratory, University of Oxford, England.]) and ORTEPII (Johnson, 1976[Johnson, C. K. (1976). ORTEPII. Report ORNL-5138. Oak Ridge National Laboratory, Tennessee, USA.]); software used to prepare material for publication: CRYSTALS.

Supporting information


Comment top

Hydantoin, (I), is of interest as the parent compound of the antiepileptic drug diphenylhydantoin and as a supramolecular synthon in its own right. Possessing equal numbers of hydrogen-bond donor (two ring NH) groups and acceptor (two carbonyl O) atoms, it can form intricate networks, but with a different presentation of these groups compared with the six-membered rings so often studied. Probably due to the difficulties with twinning described below, no structure of hydantoin has appeared in the literature. \sch

The atom-numbering scheme is shown in Fig. 1. Electron donation from the ring N atoms to the carbonyl groups, as in resonance structures (Ia)-(Ic), would be expected to lengthen the CO bonds and shorten the ring C—N bonds, C2O2 being affected from both sides. The experimental bond distances show no significant differences between the two carbonyl bond lengths or between N1—C2 and N3—C4, but C2—N3 is longer than their average by 0.024 Å (6σ). Thus resonance structure (Ib) appears to be of limited importance. Both carbonyl groups are bent towards atom N3: the angle O2—C2—N1 exceeds O2—C2—N3 by 3.8 (3)° and O4—C4—C5 exceeds O4—C4—N3 by 2.6 (3)°.

A search group was defined, consisting of a hydantoin ring with both NH groups unsubstituted and sp3 hybridization at C5. With disorder, errors or ions excluded and R < 0.1 required, a search (Bruno et al., 2002) of the Cambridge Structural Database (CSD, Version?; Allen, 2002) yielded 41 hits with 50 hydantoin rings in 49 independent molecules after removal of duplicate structure determinations. Mean values of the relevant bond distances, with standard error of the mean in parentheses, confirm the tendency in hydantoin: C2—O2 1.221 (1), C4—O4 1.211 (1), N1—C2 1.342 (2), C2—N3 1.393 (2) and N3—C4 1.362 (1) Å. Bending of one carbonyl bond is common. The mean O2—C2—N1 angle is 127.9 (1)°, compared with 124.5 (1)° for O2—C2—N3, but the other CO bond lies close to the exterior bisector, mean values being 126.8 (1)° for O4—C4—N3 and 126.3 (1)° for O4—C4—C5.

Ab initio molecular-orbital optimization of hydantoin with GAMESS (Schmidt et al., 1990) in the 6–31G* basis set corroborates the near equality of CO distances and yields N1—C2, C2—N3 and N3—C4 distances of 1.356, 1.391 and 1.367 Å, respectively. Atomic charges were calculated by the method of Löwdin (1950), chosen because it is based on orthogonalized orbitals and appears to be consistent with electronegativity. Values of −0.350 on N1, −0.382 on O2, −0.275 on N3 and −0.348 on O4 suggest that more negative charge is received by O2 than O4, and more given up by N3 than by N1.

As seen in Fig. 2, each molecule of (I) participates in N—H···O hydrogen bonds, forming a chain of centrosymmetric rings with graph set C22(9) [R22(8)] [R22(8)] (Etter, 1990; Bernstein et al., 1995). Of the 50 independent hydantoin rings found in the search of the CSD, this (pseudo-)centrosymmetric `chain of rings' arrangement occurred in five (Table 3; the atom-numbering scheme has always been made to agree with the IUPAC system used in the present study), while another six exhibited a variant form in which the more electron-dense atom O2 simultaneously accepts N1—H1···O2 and N3—H3···O2 hydrogen bonds, while atom O4 accepts none (Table 4). Chains are also possible. Hydantoins can create an infinite chain in graph set C(5) with atom N1 as donor and atom O4 as acceptor, simultaneously with another C(4) motif having atom N3 as donor and atom O2 as acceptor, thereby creating edge-fused R33(12) rings. This network had five occurrences, always in a non-centrosymmetric space group (Table 5). Scheme 2 here.

Many hydantoin derivatives carry polar substituents on the 5-position, which divert some or all of the hydrogen bonding away from the ring. Thus 21 molecules participate in a single R22(8) motif, 11 involving atom N1 as donor and atom O2 as acceptor, seven with N3 and O2, two with N3 and O4 and one with heterogeneous involvement of N1 with O4 and N3 with O2 (Table 6). Single chains also occur frequently, two C(4) using atoms N1 and O2, five C(5) with N1 and O4, four C(4) with N3 and O2 but none with N3 and O4, and one with heterogeneous chains (Table 7). Finally, three rings only interact with side groups (Table 8). (The total exceeds 50 because two molecules forming one ring and one chain are double-counted.) Of the potential hydrogen-bond donors and acceptors, atom N1 is left unused only three times, O2 just once and N3 not at all, but the less highly charged and less accessible atom O4 is unused 24 times. Thus hydantoin is a versatile supramolecular synthon providing a challenge to attempts at a priori prediction.

Experimental top

Crystals of (I), in habits ranging from stubby needles to tabular blocks, were grown by slowly cooling to room temperature a saturated aqueous solution prepared at 353 K. An attempt to obtain a more tractable crystal form by diffusing acetic acid vapour into a sample of hydantoin in 12.5% sodium hydroxide solution yielded a conglomerate of sticky needles showing the same unit cell, space group and propensity to form twins.

Refinement top

H-atom positions were refined freely, and Uiso(H) were set initially to 1.2Ueq(C,N) and not refined further. The data were refined as a two-component twin, (1 0 0, 0 1 0, 0 0 1) and (1 0 0.652, 0 − 1–0, 0 0 − 1), with twin element scale factors 0.869 (6) and 0.131 (6).

Computing details top

Data collection: COLLECT (Nonius, 1998); cell refinement: DENZO and SCALEPACK; data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR92 (Altomare et al., 1994) and SHELXL97 (Sheldrick, 1997); program(s) used to refine structure: CRYSTALS (Watkin et al., 1999); molecular graphics: CAMERON (Watkin et al., 1996) and ORTEPII (Johnson, 1976); software used to prepare material for publication: CRYSTALS.

Figures top
[Figure 1] Fig. 1. A view of the structure of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii. Hydrogen bonds are indicated by dashed lines.
[Figure 2] Fig. 2. A view of two chains of (I) extending through the unit cell, with atom N1 of four representative molecules bearing a label. The symmetry codes are: (2) 1 − x, −y, 1 − z; (3) 1/2 + x, 1/2 + y, z; (4) 3/2 − x, 1/2 − y, 1 − z. Other molecules are generated from these by adding 1 to both x and z or subtracting 1 from both x and z. Hydrogen bonds are shown as dashed lines. The new figure does not match this caption. Do you wish to amend the figure or the caption?
imidazolidine-2,4-dione top
Crystal data top
C3H4N2O2F(000) = 416.000
Mr = 100.08Dx = 1.669 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 730 reflections
a = 9.3538 (7) Åθ = 5–27°
b = 12.1757 (11) ŵ = 0.14 mm1
c = 7.2286 (6) ÅT = 190 K
β = 104.593 (4)°Plate, colourless
V = 796.70 (11) Å30.18 × 0.10 × 0.02 mm
Z = 8
Data collection top
Nonius KappaCCD area-detector
diffractometer
886 reflections with I > 10σ(I)
Graphite monochromatorRint = 0.02
ω scansθmax = 27.4°, θmin = 5.5°
Absorption correction: multi-scan
DENZO and SCALEPACK (Otwinowski & Minor, 1997)
h = 1212
Tmin = 0.99, Tmax = 1.00k = 1415
1593 measured reflectionsl = 99
886 independent reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.061Only H-atom coordinates refined
wR(F2) = 0.131 w = 1/[σ2(F*) + 1.89P]
where P = 0.333*max(Fo2,0) + (1-0.333)Fc2
S = 1.13(Δ/σ)max = 0.000095
886 reflectionsΔρmax = 0.27 e Å3
77 parametersΔρmin = 0.25 e Å3
0 restraints
Crystal data top
C3H4N2O2V = 796.70 (11) Å3
Mr = 100.08Z = 8
Monoclinic, C2/cMo Kα radiation
a = 9.3538 (7) ŵ = 0.14 mm1
b = 12.1757 (11) ÅT = 190 K
c = 7.2286 (6) Å0.18 × 0.10 × 0.02 mm
β = 104.593 (4)°
Data collection top
Nonius KappaCCD area-detector
diffractometer
886 independent reflections
Absorption correction: multi-scan
DENZO and SCALEPACK (Otwinowski & Minor, 1997)
886 reflections with I > 10σ(I)
Tmin = 0.99, Tmax = 1.00Rint = 0.02
1593 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0610 restraints
wR(F2) = 0.131Only H-atom coordinates refined
S = 1.13Δρmax = 0.27 e Å3
886 reflectionsΔρmin = 0.25 e Å3
77 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
N10.8510 (3)0.10869 (19)0.8685 (3)0.0374
C20.7974 (3)0.00484 (19)0.8218 (3)0.0271
N30.6630 (2)0.01532 (16)0.6856 (3)0.0271
C40.6326 (3)0.12247 (19)0.6338 (3)0.0280
C50.7522 (3)0.1883 (2)0.7508 (4)0.0326
O40.5237 (2)0.15458 (14)0.5136 (3)0.0376
O20.8518 (2)0.08264 (14)0.8866 (3)0.0366
H510.802 (3)0.224 (3)0.685 (5)0.0388*
H520.723 (3)0.236 (3)0.815 (5)0.0388*
H10.943 (3)0.119 (2)0.959 (4)0.0309*
H30.610 (4)0.038 (3)0.623 (5)0.0500*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0327 (12)0.0373 (12)0.0362 (13)0.004 (1)0.003 (1)0.0052 (9)
C20.0268 (12)0.0249 (11)0.0285 (11)0.0012 (9)0.0050 (9)0.0002 (9)
N30.027 (1)0.0198 (9)0.0303 (11)0.0027 (7)0.0006 (8)0.0005 (7)
C40.0328 (12)0.0236 (11)0.0255 (12)0.0033 (9)0.0035 (9)0.0005 (8)
C50.0474 (15)0.0179 (11)0.0314 (13)0.003 (1)0.0077 (11)0.0001 (9)
O40.0437 (11)0.0257 (9)0.035 (1)0.0016 (7)0.0063 (8)0.0020 (7)
O20.036 (1)0.0262 (9)0.0417 (11)0.0036 (7)0.0009 (8)0.0020 (7)
Geometric parameters (Å, º) top
C2—O21.222 (3)C4—C51.460 (3)
C2—N11.371 (3)C5—H520.83 (3)
C2—N31.393 (3)C5—H510.86 (3)
N3—H30.87 (4)C5—N11.457 (3)
N3—C41.367 (3)N1—H10.95 (3)
C4—O41.225 (3)
O2—C2—N1128.2 (2)H52—C5—H51105 (3)
O2—C2—N3124.4 (2)H52—C5—N1113 (2)
N3—C2—N1107.4 (2)H51—C5—N1108 (2)
H3—N3—C4121 (2)H52—C5—C4114 (2)
H3—N3—C2127 (2)H51—C5—C4114 (2)
C4—N3—C2111.67 (19)N1—C5—C4104.7 (2)
O4—C4—C5127.9 (2)H1—N1—C2120.5 (17)
O4—C4—N3125.3 (2)H1—N1—C5130.0 (17)
C5—C4—N3106.8 (2)C2—N1—C5109.4 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O2i0.95 (3)2.01 (3)2.913 (3)158
N3—H3···O4ii0.87 (4)1.98 (4)2.852 (3)176
Symmetry codes: (i) x+2, y, z+2; (ii) x+1, y, z+1.

Experimental details

Crystal data
Chemical formulaC3H4N2O2
Mr100.08
Crystal system, space groupMonoclinic, C2/c
Temperature (K)190
a, b, c (Å)9.3538 (7), 12.1757 (11), 7.2286 (6)
β (°) 104.593 (4)
V3)796.70 (11)
Z8
Radiation typeMo Kα
µ (mm1)0.14
Crystal size (mm)0.18 × 0.10 × 0.02
Data collection
DiffractometerNonius KappaCCD area-detector
diffractometer
Absorption correctionMulti-scan
DENZO and SCALEPACK (Otwinowski & Minor, 1997)
Tmin, Tmax0.99, 1.00
No. of measured, independent and
observed [I > 10σ(I)] reflections
1593, 886, 886
Rint0.02
(sin θ/λ)max1)0.648
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.061, 0.131, 1.13
No. of reflections886
No. of parameters77
H-atom treatmentOnly H-atom coordinates refined
Δρmax, Δρmin (e Å3)0.27, 0.25

Computer programs: COLLECT (Nonius, 1998), DENZO and SCALEPACK (Otwinowski & Minor, 1997), SIR92 (Altomare et al., 1994) and SHELXL97 (Sheldrick, 1997), CRYSTALS (Watkin et al., 1999), CAMERON (Watkin et al., 1996) and ORTEPII (Johnson, 1976), CRYSTALS.

Selected geometric parameters (Å, º) top
C2—O21.222 (3)C4—C51.460 (3)
C2—N11.371 (3)C5—H520.83 (3)
C2—N31.393 (3)C5—H510.86 (3)
N3—H30.87 (4)C5—N11.457 (3)
N3—C41.367 (3)N1—H10.95 (3)
C4—O41.225 (3)
O2—C2—N1128.2 (2)O4—C4—N3125.3 (2)
O2—C2—N3124.4 (2)C5—C4—N3106.8 (2)
N3—C2—N1107.4 (2)N1—C5—C4104.7 (2)
C4—N3—C2111.67 (19)C2—N1—C5109.4 (2)
O4—C4—C5127.9 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O2i0.95 (3)2.01 (3)2.913 (3)158
N3—H3···O4ii0.87 (4)1.98 (4)2.852 (3)176
Symmetry codes: (i) x+2, y, z+2; (ii) x+1, y, z+1.
Hydantoin derivatives in the CSD forming the same C22(9)[R22(8)] [R22(8)] network as hydantoin, or a comparable network with a pseudo-centre of inversion top
RefcodeSpace groupD-H···AReference
BCOCHYC2/mN1-H···O2Smith-Verdier et al. (1979a)
N3-H···O4
GRNSHY mol 1P1N1-H···O2"Florencio et al. (1980)
N3-H···O4"
GRNSHY mol 2P1N1-H"···O2
N3-H"···O4
OCSHYDC2/cN1-H···O2Miller and McPhail (1979)
N3-H···O4
VARBARP21/cN1-H···O2Rizzi et al. (1989)
N3-H···O4
Hydantoin derivatives forming a C11(4) C11(4) [R22(8)] network based on N1-H.·O2 and N3-H.·O2 hydrogen bonds with O4 not used top
RefcodeSpace groupD-H···AReference
ADUQOFP212121N1-H···O2Beilles et al. (2001)
N3-H···O2
BEPNITP212121N1-H···O2Cassady and Hawkinson (1982)
N3-H···O2
HPHCMSP21N1-H···O2Koch et al. (1975)
N3-H···O4
OGUVIVP21N1-H···O2Stalker et al. (2002)
N3-H···O4
XERTUJ mol 1P21N1-H···O2"Koos et al. (2000)
N3-H···O2"
XERTUJ mol 2P21N1-H"···O2
N3-H"···O2
Hydantoin derivatives forming a chain of edge-fused R33(12) rings top
RefcodeSpace groupD-H···AReference
DAFFIZ01P212121N1-H···O4Sarges et al. (1985)
N3-H···O2
LABTIRP212121N1-H···O4Coquerel et al. (1993)
N3-H···O2
PHYDANPn21aN1-H···O4Camerman and Camerman (1971)
N3-H···O2
PIPVALP21N1-H···O4Modric et al. (1993)
N3-H···O2
YECDOZP212121N1-H···O4Park et al. (1994)
N3-H···O2
Hydantoin derivatives forming a single [R22(8)] motif top
RefcodeSpace groupD-H···AReference
BICSIPP21/nN1-H···O2Florencio et al. (1982)
CECKUQP1N1-H···O2Galvez et al. (1983)
DPHEAD20 mol 1P1N1-H···O2Mastropaolo et al. (1983)
EZOSHYP21/cN1-H···O2Smith-Verdier et al. (1979b)
MANHDT10P21/nN1-H···O2Vilches et al. (1981)
MESYIS mol 1P1N1-H···O2"Koos et al. (2001)
MESYIS mol 2P1N1-H"···O2
MGSHYD10 mol 1P21N1-H···O2"Florencio et al. (1978a)
MGSHYD10 mol 2P21N1-H"···O2
MZBSHYP21/nN1-H···O2Florencio et al. (1979)
TRSHYD10P21/cN1-H···O2Smith-Verdier et al. (1977)
ALATIN01P21/cN3-H···O2Zhang et al. (1992)
DPHEAD20 mol 2P1N3-H···O2Mastropaolo et al. (1983)
DPHPZLP1N3-H···O2Uno and Shimizu (1980)
HEGRAHP21/cN3-H···O2Florencio et al. (1978b)
VAPZUHP21/cN3-H···O2Rizzi et al. (1989)
XERTOD mol 1P43N3-H···O2"Koos et al. (2000)
XERTOD mol 2P43N3-H"···O2
AHINEKP21/cN3-H···O4SethuSankar et al. (2002)
NIVZOHP21/cN3-H···O4Benedetti et al. (1997)
COQQEEaP21N1-H···O4"Mullica et al. (1998)
N3-H"···O2
(a) Although Z'=1, the molecule has an independent hydantoin ring at each end.
Hydantoin derivatives forming a single chain motif top
RefcodeSpace groupD-H···AReference
NIVZOHP21/cN1-H···O2Benedetti et al. (1997)
TOTPIBP21N1-H···O2Bravo et al. (1996)
BAGXOWP21/cN1-H···O4Terzis et al. (1981)
HOIMCU mol 1P21/nN1-H···O4Poje et al. (1980)
ROKSOZPna21N1-H···O4Gauthier et al. (1997)
SINZEUP212121N1-H···O4Galdecki et al. (1986)
VAPZUHP21/cN1-H···O4Rizzi et al. (1989)
GODRASP212121N3-H···O2Eknoian et al. (1999)
GOPZIU mol 1P21N3-H···O2"Agasimundin et al. (1998)
GOPZIU mol 2P21N3-H"···O2
ROKSUFP21/cN3-H···O2Gauthier et al. (1997)
COQQEEaP21N3-H···O2"Mullica et al. (1998)
N1-H"···O4
(a) Although Z'=1, the molecule has an independent hydantoin ring at each end.
Hydantoin derivatives without ring-to-ring hydrogen bonding top
RefcodeSpace groupD-H···AReference
HOIMCU mol 2P21/nNonePoje et al. (1980)
JOPPAFP21NoneYamagishi et al. (1992)
QIBNIYP21/cNoneSethuSankar et al. (2001)
 

Acknowledgements

The authors thank the Cambridge Crystallographic Data Centre for providing the CSD at Aston University.

References

First citationAgasimundin, Y. S., Mumper, M. W. & Hosmane, R. S. (1998). Bioorg. Med. Chem. 6, 911–923.  Google Scholar
First citationAllen, F. H. (2002). Acta Cryst. B58, 380–388.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationAltomare, A., Cascarano, G., Giacovazzo, C., Guagliardi, A., Burla, M. C., Polidori, G. & Camalli, M. (1994). J. Appl. Cryst. 27, 435.  CrossRef Web of Science IUCr Journals Google Scholar
First citationBeilles, S., Cardinael, P., Ndzie, E., Petit, S. & Coquerel, G. (2001). Chem. Eng. Sci. 56, 2281–2294.  Google Scholar
First citationBenedetti, E., DiBlasio, B., Iacovino, R., Menchize, V., Saviano, M., Pedone, C., Bonora, G. M., Ettorre, A., Graci, L., Formaggio, F., Crisma, M., Valle, G. & Toniolo, C. (1997). J. Chem. Soc. Perkin Trans. 2, pp. 2023–2032.  Google Scholar
First citationBernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555–1573.  CrossRef CAS Web of Science Google Scholar
First citationBravo, P., Capelli, S., Meille, S. V., Seresini, P., Volonterio, A. & Zanda, M. (1996). Tetrahedron: Asymmetry, 7, 2321–2332.  Google Scholar
First citationBruno, I. J., Cole, J. C., Edgington, P. R., Kessler, M., Macrae, C. F., McCabe, P., Pearson, J. & Taylor, R. (2002). Acta Cryst. B58, 389–397.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationCamerman, A. & Camerman, N. (1971). Acta Cryst. B27, 2205–2211.  CSD CrossRef IUCr Journals Web of Science Google Scholar
First citationCassady, R. E. & Hawkinson, S. W. (1982). Acta Cryst. B38, 1646–1647.  CrossRef IUCr Journals Google Scholar
First citationCoquerel, G., Petit, M. N. & Robert, F. (1993). Acta Cryst. C49, 824–825.  CSD CrossRef CAS Web of Science IUCr Journals Google Scholar
First citationEknoian, M. W., Webb, T. R., Worley, S. D., Braswell, A. & Hadley, J. (1999). Acta Cryst. C55, 405–407.  CSD CrossRef IUCr Journals Google Scholar
First citationEtter, M. C. (1990). Acc. Chem. Res. 23, 120–126.  CrossRef CAS Web of Science Google Scholar
First citationFlorencio, F., Smith-Verdier, P. & García-Blanco, S. (1978a). Acta Cryst. B34, 1317–1321.  CrossRef IUCr Journals Google Scholar
First citationFlorencio, F., Smith-Verdier, P. & García-Blanco, S. (1978b). Acta Cryst. B34, 2220–2223.  CrossRef IUCr Journals Google Scholar
First citationFlorencio, F., Smith-Verdier, P. & García-Blanco, S. (1979). Acta Cryst. B35, 2422–2424.  CrossRef IUCr Journals Google Scholar
First citationFlorencio, F., Smith-Verdier, P. & García-Blanco, S. (1980). Cryst. Struct. Commun. 9, 687–692.  Google Scholar
First citationFlorencio, F., Smith-Verdier, P. & García-Blanco, S. (1982). Acta Cryst. B38, 2089–2091.  CrossRef IUCr Journals Google Scholar
First citationGaldecki, Z. & Karolak-Wojciechowska, J. (1986). J. Crystallogr. Spectrosc. Res. 16, 467–474.  CAS Google Scholar
First citationGalvez, E., Martinez, M., Gonzalez, J., Trigo, G. G., Smith-Verdier, P., Florencio, F. & García-Blanco, S. (1983). J. Pharm. Sci. 72, 881–886.  Google Scholar
First citationGauthier, T. J., Yokum, T. S., Morales, G. A., McLaughlin, M. L., Liu, Y.-H. & Fronczek, F. R. (1997). Acta Cryst. C53, 1659–1661.  CSD CrossRef CAS Web of Science IUCr Journals Google Scholar
First citationJohnson, C. K. (1976). ORTEPII. Report ORNL-5138. Oak Ridge National Laboratory, Tennessee, USA.  Google Scholar
First citationKoch, M. H. J., Germain, G., Declercq, J. P. & Dusausoy, Y. (1975). Acta Cryst. B31, 2547–2549.  CrossRef IUCr Journals Google Scholar
First citationKoos, M., Steiner, B., Langer, V., Gyepesova, D. & Durik, M. (2000). Carbohydr. Res. 328, 115–126.  Google Scholar
First citationKoos, M., Steiner, B., Micova, J., Langer, V., Durik, M. & Gyepesova, D. (2001). Carbohydr. Res. 332, 351–361.  Google Scholar
First citationLöwdin, P. O. (1950). J. Chem. Phys. 18, 365–370.  Google Scholar
First citationMastropaolo, D., Camerman, A. & Camerman, N. (1983). Mol. Pharmacol. 23, 273–277.  Google Scholar
First citationMiller, R. W. & McPhail, A. T. (1979). J. Chem. Res. pp. 330–331.  Google Scholar
First citationModric, N., Poje, M., Watkin, D. J. & Edwards, A. J. (1993). Tetrahedron Lett. 34, 4679–4682.  Google Scholar
First citationMullica, D. F., Trawick, M. L., Wu, P. W. N. & Sappenfield, E. L. (1998). J. Chem. Crystallogr. 28, 761–765.  Web of Science CSD CrossRef CAS Google Scholar
First citationNonius (1998). COLLECT. Nonius BV, Delft, The Netherlands.  Google Scholar
First citationOtwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307–326. New York: Academic Press.  Google Scholar
First citationPark, H.-G., Vela, M. A. & Kohn, H. (1994). J. Am. Chem. Soc. 116, 471–478.  Google Scholar
First citationPoje, M., Paulus, E. F. & Rocic, B. (1980). J. Org. Chem. 45, 65–68.  Google Scholar
First citationRizzi, J. P., Schnur, R. C., Hutson, N. J., Kraus, K. G. & Kelbaugh, P. R. (1989). J. Med. Chem. 32, 1208–1213.  Google Scholar
First citationSarges, R., Bordner, J., Dominy, B. W., Peterson, M. J. & Whipple, E. B. (1985). J. Med. Chem. 28, 1716–1720.  Google Scholar
First citationSchmidt, M. W., Baldridge, K. K., Boatz, J. A., Jensen, J. H., Koseki, S., Gordon, M. S., Nguyen, K. A., Windus, T. L. & Elbert, S. T. (1990). QCPE Bull. 10, 52–54.  Google Scholar
First citationSethuSankar, K., Thennarasu, S., Velmurugan, D. & Kim, M. J. (2002). Acta Cryst. C58, o715–o717.  CSD CrossRef CAS IUCr Journals Google Scholar
First citationSethuSankar, K., Thennarasu, S., Velmurugan, D., Shanmuga Sundara Raj, S., Fun, H.-K. & Perumal, P. T. (2001). Acta Cryst. E57, o377–o379.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationSheldrick, G. M. (1997). SHELXL97. University of Göttingen, Germany.  Google Scholar
First citationSmith-Verdier, P., Florencio, F. & García-Blanco, S. (1977). Acta Cryst. B33, 3381–3385.  CrossRef IUCr Journals Google Scholar
First citationSmith-Verdier, P., Florencio, F. & García-Blanco, S. (1979a). Acta Cryst. B35, 216–217.  CrossRef IUCr Journals Google Scholar
First citationSmith-Verdier, P., Florencio, F. & García-Blanco, S. (1979b). Acta Cryst. B35, 1911–1913.  CrossRef IUCr Journals Google Scholar
First citationStalker, R. A., Munsch,, T. E., Tran, J. D., Nie, X., Warmuth, R., Beatty, A. & Aakeroy, C. B. (2002). Tetrahedron, 58, 4837–4849.  Google Scholar
First citationTerzis, A., Filippakis, S. E. & Mentzafos, D. (1981). Cryst. Struct. Commun. 10, 803–806.  Google Scholar
First citationUno, T. & Shimizu, N. (1980). Acta Cryst. B36, 2794–2796.  CrossRef IUCr Journals Google Scholar
First citationVilches, J., Florencio, F., Smith-Verdier, P. & García-Blanco, S. (1981). Acta Cryst. B37, 201–204.  CrossRef IUCr Journals Google Scholar
First citationWatkin, D. J., Prout, C. K., Carruthers, J. R. & Betteridge, P. W. (1999). CRYSTALS. Issue 11. Chemical Crystallography Laboratory, Oxford, England.  Google Scholar
First citationWatkin, D. J., Prout, C. K. & Pearce, L. J. (1996). CAMERON. Chemical Crystallography Laboratory, University of Oxford, England.  Google Scholar
First citationYamagishi, M., Yamada, Y., Ozaki, K., Da-te, T., Okamura, K., Suzuki, M. & Matsumoto, K. (1992). J. Org. Chem. 57, 1568–1571.  CSD CrossRef CAS Web of Science Google Scholar
First citationZhang, J., Zhang, Z., You, K. & Fan, Y. (1992). Jilin Daxue Ziran Kexue Xuebao (Acta Sci. Nat. Univ. Jilin), pp. 87–89. (In Chinese.)  Google Scholar

© International Union of Crystallography. Prior permission is not required to reproduce short quotations, tables and figures from this article, provided the original authors and source are cited. For more information, click here.

Journal logoSTRUCTURAL
CHEMISTRY
ISSN: 2053-2296
Follow Acta Cryst. C
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds