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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 65| Part 4| April 2009| Pages o748-o749

Bis(4-amino­pyridinium) bis­(hydrogen oxalate) monohydrate

aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, and bDepartment of Physics, National Institute of Technology, Tiruchirappalli 620015, India
*Correspondence e-mail: hkfun@usm.my

(Received 25 February 2009; accepted 27 February 2009; online 14 March 2009)

In the title compound, 2C5H7N2+·2C2HO4·H2O, the asymmetric unit consists of an amino­pyridinium cation, an oxalic actetate anion and a half-molecule of water, which lies on a two-fold rotation axis. The crystal packing is consolidated by inter­molecular O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds. The mol­ecules are linked into an infinite one dimensional chain along [010].

Related literature

For the biological activity of 4-amino­pyridine, see: Judge & Bever (2006[Judge, S. & Bever, C. (2006). Pharmacol. Ther. 111, 224-259.]); Schwid et al. (1997[Schwid, S. B., Petrie, M. D., McDermott, M. P., Tierney, D. S., Mason, D. H. & Goodman, A. D. (1997). Neurology, 48, 817-821.]); Strupp et al. (2004[Strupp, M., Kalla, R., Dichgans, M., Fraitinger, T., Glasauer, S. & Brandt, T. (2004). Neurology, 62, 1623-1625.]). For the structure of oxalic acid, see: Derissen & Smith (1974[Derissen, J. L. & Smith, P. H. (1974). Acta Cryst. B30, 2240-2242.]). For related structures, see: Anderson et al. (2005[Anderson, F. P., Gallagher, J. F., Kenny, P. T. M. & Lough, A. J. (2005). Acta Cryst. E61, o1350-o1353.]); Bhattacharya et al. (1994[Bhattacharya, S., Dastidar, P. & Guru Row, T. N. (1994). Chem. Mater. 6, 531-537.]); Chao & Schempp (1977[Chao, M. & Schempp, E. (1977). Acta Cryst. B33, 1557-1564.]); Karle et al. (2003[Karle, I., Gilardi, R. D., Chandrashekhar Rao, Ch., Muraleedharan, K. M. & Ranganathan, S. (2003). J. Chem. Crystallogr. 33, 727-749.]). For stability of the temperature controller, see: Cosier & Glazer (1986[Cosier, J. & Glazer, A. M. (1986). J. Appl. Cryst. 19, 105-107.]).

[Scheme 1]

Experimental

Crystal data
  • 2C5H7N2+·2C2HO4·H2O

  • Mr = 386.32

  • Monoclinic, C 2/c

  • a = 15.6429 (6) Å

  • b = 5.6929 (2) Å

  • c = 19.9091 (7) Å

  • β = 105.617 (2)°

  • V = 1707.52 (11) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.13 mm−1

  • T = 100 K

  • 0.49 × 0.34 × 0.11 mm

Data collection
  • Bruker SMART APEXII CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2005[Bruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.906, Tmax = 0.986

  • 12438 measured reflections

  • 2467 independent reflections

  • 2159 reflections with I > 2σ(I)

  • Rint = 0.027

Refinement
  • R[F2 > 2σ(F2)] = 0.034

  • wR(F2) = 0.096

  • S = 1.03

  • 2467 reflections

  • 159 parameters

  • All H-atom parameters refined

  • Δρmax = 0.35 e Å−3

  • Δρmin = −0.24 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O1W—H2W1⋯O4i 0.874 (18) 1.895 (18) 2.7676 (9) 175.0 (18)
N2—H1N2⋯O4ii 0.877 (15) 1.983 (16) 2.8556 (11) 173.4 (14)
N2—H2N2⋯O1Wiii 0.890 (16) 1.993 (15) 2.8620 (12) 164.8 (13)
N1—H1N1⋯O3iv 0.863 (17) 2.100 (17) 2.8645 (11) 147.3 (15)
N1—H1N1⋯O2iv 0.863 (17) 2.218 (17) 2.8818 (11) 133.6 (15)
O1—H1O1⋯O3v 1.00 (2) 1.60 (2) 2.5916 (10) 177.6 (18)
C5—H5⋯O2vi 0.951 (13) 2.361 (14) 3.1585 (12) 141.2 (11)
Symmetry codes: (i) -x+1, -y+1, -z+1; (ii) [x, -y+1, z+{\script{1\over 2}}]; (iii) x, y+1, z; (iv) [x-{\script{1\over 2}}, y+{\script{1\over 2}}, z]; (v) x, y-1, z; (vi) [x-{\script{1\over 2}}, y+{\script{3\over 2}}, z].

Data collection: APEX2 (Bruker, 2005[Bruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2005[Bruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]).

Supporting information


Comment top

4-Aminopyridine (Fampridine) is used clinically in Lambert-Eaton myasthenic syndrome and multiple sclerosis because by blocking potassium channels it prolongs action potentials thereby increasing transmitter release at the neuromuscular junction (Judge & Bever, 2006; Schwid et al., 1997; Strupp et al., 2004). The structure of 4-aminopyridine has already been reported (Chao & Schempp, 1977). Redetermination of the structure of 4-aminopyridine has been reported (Anderson et al., 2005). The crystal structure of oxalic acid monohydrate has been reported (Derissen & Smith, 1974). As an extension of our systematic study of the hydrogen bonding patterns of 4-aminopyridine with carboxylic acids, the title compound (I) has been synthesized and the crystal structure determined.

The asymmetric unit of (I) (Fig. 1) contains one molecule of 4-aminopyridine cation, one molecule of oxalate anion and half-a-molecule of water. A proton transfer from the carboxyl group of oxalic acid to atom N1 of 4-aminopyridine resulted in the formation of salts. This protonation lead to the widening of C1–N1–C5 angle of the pyridine ring to 121.0 (8)°, compared to 115.25 (13)° in the unprotonated 4-aminopyridine (Anderson et al., 2005). This type of protonation is observed in various 4-aminopyridine acid complexes (Bhattacharya et al., 1994; Karle et al., 2003). The bond lengths and bond angles of the 4-aminopyridine are comparable to the values reported earlier for 4-aminopyridine (Chao & Schempp, 1977; Anderson et al., 2005). The 4-aminopyridine ring is essentially planar with the maximum deviation from planarity being 0.0075 (9)Å for atom N1. The bond lengths and bond angles of the oxalate are comparable to the values reported for oxalic acid (Derissen & Smith, 1974).

The crystal packing is consolidated by intermolecular O—H···O, N—H···O and C—H···O hydrogen bonds (Table 1). Intermolecular short contacts of O—O = 2.5916 (10)i to 2.7074 (10)Å and N—O = 2.8557 (11)ii to 2.8646 (11)iiiÅ are observed [symmetry codes: (i) x,-1 + y,z; (ii) x,1 - y,1/2 + z; (iii) -1/2 + x,1/2 + y,z]. The molecules are linked into a 3-D network (Fig. 2).

Related literature top

For the biological activity of 4-aminopyridine, see: Judge & Bever (2006); Schwid et al. (1997); Strupp et al. (2004). For the structure of oxalic acid, see: Derissen & Smith (1974). For related structures, see: Anderson et al. (2005); Bhattacharya et al. (1994); Chao & Schempp (1977); Karle et al. (2003). For stability of the temperature controller, see: Cosier & Glazer (1986).

Experimental top

Equimolar quantities of 4-aminopyridine (0.094 g, 1 mmol) and oxalic acid (0.090 g, 1 mmol) were dissolved in 25 ml water. The solution was refluxed at 323 K for 12 h. Colourless crystals were harvested after two months of solvent evaporation.

Refinement top

All the hydrogen atoms were located from the Fourier map and were allowed to refine freely.

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atom numbering scheme.
[Figure 2] Fig. 2. The crystal packing of the title compound, viewed down the c axis. Dashed lines indicate the hydrogen bonding.
Bis(4-aminopyridinium) bis(hydrogen oxalate) monohydrate top
Crystal data top
2C5H7N2+·2C2HO4·H2OF(000) = 808
Mr = 386.32Dx = 1.503 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 7009 reflections
a = 15.6429 (6) Åθ = 2.7–38.8°
b = 5.6929 (2) ŵ = 0.13 mm1
c = 19.9091 (7) ÅT = 100 K
β = 105.617 (2)°Plate, colourless
V = 1707.52 (11) Å30.49 × 0.34 × 0.11 mm
Z = 4
Data collection top
Bruker SMART APEXII CCD area-detector
diffractometer
2467 independent reflections
Radiation source: fine-focus sealed tube2159 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.027
ϕ and ω scansθmax = 30.0°, θmin = 2.1°
Absorption correction: multi-scan
(SADABS; Bruker, 2005)
h = 2221
Tmin = 0.906, Tmax = 0.986k = 77
12438 measured reflectionsl = 2728
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.034Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.096All H-atom parameters refined
S = 1.03 w = 1/[σ2(Fo2) + (0.0564P)2 + 0.8323P]
where P = (Fo2 + 2Fc2)/3
2467 reflections(Δ/σ)max < 0.001
159 parametersΔρmax = 0.35 e Å3
0 restraintsΔρmin = 0.24 e Å3
Crystal data top
2C5H7N2+·2C2HO4·H2OV = 1707.52 (11) Å3
Mr = 386.32Z = 4
Monoclinic, C2/cMo Kα radiation
a = 15.6429 (6) ŵ = 0.13 mm1
b = 5.6929 (2) ÅT = 100 K
c = 19.9091 (7) Å0.49 × 0.34 × 0.11 mm
β = 105.617 (2)°
Data collection top
Bruker SMART APEXII CCD area-detector
diffractometer
2467 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2005)
2159 reflections with I > 2σ(I)
Tmin = 0.906, Tmax = 0.986Rint = 0.027
12438 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0340 restraints
wR(F2) = 0.096All H-atom parameters refined
S = 1.03Δρmax = 0.35 e Å3
2467 reflectionsΔρmin = 0.24 e Å3
159 parameters
Special details top

Experimental. The crystal was placed in the cold stream of an Oxford Cyrosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.50462 (4)0.16951 (12)0.39445 (3)0.01643 (15)
O20.59652 (5)0.02380 (12)0.49260 (3)0.01700 (16)
O30.55682 (5)0.41624 (12)0.44228 (4)0.02023 (17)
O40.45356 (5)0.26647 (12)0.35138 (3)0.01903 (16)
N10.18206 (5)0.86694 (16)0.57611 (4)0.01960 (18)
N20.39056 (6)1.06075 (16)0.74035 (4)0.01829 (17)
C10.20886 (7)0.72101 (18)0.63132 (5)0.0199 (2)
C20.27784 (6)0.77998 (18)0.68707 (5)0.01844 (19)
C30.32276 (6)0.99712 (16)0.68737 (5)0.01467 (18)
C40.29134 (6)1.14587 (17)0.62850 (5)0.01667 (19)
C50.22175 (6)1.07631 (18)0.57489 (5)0.0188 (2)
C60.54297 (6)0.00122 (16)0.43617 (4)0.01357 (17)
C70.51411 (6)0.25017 (16)0.40655 (5)0.01471 (18)
O1W0.50000.46896 (19)0.75000.0215 (2)
H2W10.5135 (12)0.560 (3)0.7190 (9)0.048 (5)*
H10.1765 (9)0.574 (3)0.6285 (7)0.028 (3)*
H20.2966 (9)0.673 (3)0.7268 (8)0.029 (4)*
H40.3195 (9)1.295 (3)0.6250 (7)0.023 (3)*
H50.1983 (9)1.169 (2)0.5344 (7)0.021 (3)*
H1N20.4086 (10)0.968 (3)0.7766 (8)0.028 (4)*
H2N20.4168 (9)1.197 (3)0.7367 (7)0.025 (3)*
H1N10.1413 (11)0.823 (3)0.5397 (9)0.038 (4)*
H1O10.5253 (12)0.327 (4)0.4140 (9)0.054 (5)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0207 (3)0.0102 (3)0.0151 (3)0.0000 (2)0.0007 (2)0.0013 (2)
O20.0197 (3)0.0137 (3)0.0141 (3)0.0009 (2)0.0014 (3)0.0004 (2)
O30.0259 (4)0.0109 (3)0.0186 (3)0.0014 (2)0.0033 (3)0.0011 (2)
O40.0249 (4)0.0141 (3)0.0136 (3)0.0010 (2)0.0027 (3)0.0007 (2)
N10.0176 (4)0.0215 (4)0.0160 (4)0.0005 (3)0.0017 (3)0.0030 (3)
N20.0178 (4)0.0182 (4)0.0152 (4)0.0017 (3)0.0019 (3)0.0011 (3)
C10.0196 (4)0.0165 (5)0.0221 (5)0.0023 (3)0.0031 (4)0.0012 (3)
C20.0192 (4)0.0166 (4)0.0176 (4)0.0011 (3)0.0017 (3)0.0028 (3)
C30.0149 (4)0.0143 (4)0.0140 (4)0.0012 (3)0.0022 (3)0.0006 (3)
C40.0177 (4)0.0143 (4)0.0165 (4)0.0008 (3)0.0019 (3)0.0017 (3)
C50.0182 (4)0.0205 (5)0.0152 (4)0.0032 (3)0.0002 (3)0.0025 (3)
C60.0158 (4)0.0112 (4)0.0133 (4)0.0001 (3)0.0032 (3)0.0002 (3)
C70.0188 (4)0.0112 (4)0.0132 (4)0.0003 (3)0.0027 (3)0.0002 (3)
O1W0.0307 (6)0.0146 (5)0.0188 (5)0.0000.0061 (4)0.000
Geometric parameters (Å, º) top
O1—C61.3139 (11)C1—C21.3654 (13)
O1—H1O11.00 (2)C1—H10.973 (15)
O2—C61.2155 (11)C2—C31.4211 (13)
O3—C71.2611 (11)C2—H20.979 (15)
O4—C71.2458 (11)C3—C41.4221 (12)
N1—C51.3471 (14)C4—C51.3621 (13)
N1—C11.3514 (13)C4—H40.966 (15)
N1—H1N10.863 (17)C5—H50.951 (13)
N2—C31.3291 (12)C6—C71.5547 (13)
N2—H1N20.877 (15)O1W—H2W10.874 (18)
N2—H2N20.890 (16)
C6—O1—H1O1111.9 (11)N2—C3—C4121.12 (9)
C5—N1—C1121.00 (8)C2—C3—C4116.98 (8)
C5—N1—H1N1118.7 (11)C5—C4—C3119.91 (9)
C1—N1—H1N1120.2 (11)C5—C4—H4118.8 (8)
C3—N2—H1N2120.1 (10)C3—C4—H4121.3 (8)
C3—N2—H2N2117.4 (9)N1—C5—C4121.21 (9)
H1N2—N2—H2N2122.5 (13)N1—C5—H5115.6 (8)
N1—C1—C2120.95 (9)C4—C5—H5123.2 (9)
N1—C1—H1116.1 (8)O2—C6—O1125.55 (8)
C2—C1—H1123.0 (8)O2—C6—C7121.00 (8)
C1—C2—C3119.93 (9)O1—C6—C7113.45 (7)
C1—C2—H2120.2 (9)O4—C7—O3127.09 (8)
C3—C2—H2119.9 (9)O4—C7—C6118.46 (8)
N2—C3—C2121.90 (9)O3—C7—C6114.44 (8)
C5—N1—C1—C20.98 (15)C1—N1—C5—C41.41 (15)
N1—C1—C2—C30.29 (15)C3—C4—C5—N10.56 (15)
C1—C2—C3—N2179.57 (9)O2—C6—C7—O4173.95 (8)
C1—C2—C3—C41.08 (14)O1—C6—C7—O46.47 (12)
N2—C3—C4—C5179.98 (9)O2—C6—C7—O36.58 (13)
C2—C3—C4—C50.67 (14)O1—C6—C7—O3173.00 (8)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1W—H2W1···O4i0.874 (18)1.895 (18)2.7676 (9)175.0 (18)
N2—H1N2···O4ii0.877 (15)1.983 (16)2.8556 (11)173.4 (14)
N2—H2N2···O1Wiii0.890 (16)1.993 (15)2.8620 (12)164.8 (13)
N1—H1N1···O3iv0.863 (17)2.100 (17)2.8645 (11)147.3 (15)
N1—H1N1···O2iv0.863 (17)2.218 (17)2.8818 (11)133.6 (15)
O1—H1O1···O3v1.00 (2)1.60 (2)2.5916 (10)177.6 (18)
C5—H5···O2vi0.951 (13)2.361 (14)3.1585 (12)141.2 (11)
Symmetry codes: (i) x+1, y+1, z+1; (ii) x, y+1, z+1/2; (iii) x, y+1, z; (iv) x1/2, y+1/2, z; (v) x, y1, z; (vi) x1/2, y+3/2, z.

Experimental details

Crystal data
Chemical formula2C5H7N2+·2C2HO4·H2O
Mr386.32
Crystal system, space groupMonoclinic, C2/c
Temperature (K)100
a, b, c (Å)15.6429 (6), 5.6929 (2), 19.9091 (7)
β (°) 105.617 (2)
V3)1707.52 (11)
Z4
Radiation typeMo Kα
µ (mm1)0.13
Crystal size (mm)0.49 × 0.34 × 0.11
Data collection
DiffractometerBruker SMART APEXII CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2005)
Tmin, Tmax0.906, 0.986
No. of measured, independent and
observed [I > 2σ(I)] reflections
12438, 2467, 2159
Rint0.027
(sin θ/λ)max1)0.703
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.034, 0.096, 1.03
No. of reflections2467
No. of parameters159
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.35, 0.24

Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1W—H2W1···O4i0.874 (18)1.895 (18)2.7676 (9)175.0 (18)
N2—H1N2···O4ii0.877 (15)1.983 (16)2.8556 (11)173.4 (14)
N2—H2N2···O1Wiii0.890 (16)1.993 (15)2.8620 (12)164.8 (13)
N1—H1N1···O3iv0.863 (17)2.100 (17)2.8645 (11)147.3 (15)
N1—H1N1···O2iv0.863 (17)2.218 (17)2.8818 (11)133.6 (15)
O1—H1O1···O3v1.00 (2)1.60 (2)2.5916 (10)177.6 (18)
C5—H5···O2vi0.951 (13)2.361 (14)3.1585 (12)141.2 (11)
Symmetry codes: (i) x+1, y+1, z+1; (ii) x, y+1, z+1/2; (iii) x, y+1, z; (iv) x1/2, y+1/2, z; (v) x, y1, z; (vi) x1/2, y+3/2, z.
 

Footnotes

Permanent address: Department of Physics, Karunya University, Karunya Nagar, Coimbatore 641114, India.

Acknowledgements

HKF and SRJ thank the Malaysian Government and Universiti Sains Malaysia for the Science Fund grant No. 305/PFIZIK/613312. SRJ thanks Universiti Sains Malaysia for a post–doctoral research fellowship. HKF also thanks Universiti Sains Malaysia for the Research University Golden Goose grant No.1001/PFIZIK/811012.

References

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Volume 65| Part 4| April 2009| Pages o748-o749
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