Issue contents
Download PDF of article
Download CIF
3D view
Navigation
Highlighting
Dictionary of Crystallography reference
IUPAC Gold Book reference
more ...
Download citation
FormatBIBTeX
EndNote
RefMan
Refer
Medline
CIF
SGML
Plain Text
share
Previous article
Next article
Previous article
Issue contents
Download PDF of article
Download CIF
3D view
Navigation
Highlighting
Dictionary of Crystallography reference
IUPAC Gold Book reference
more ...
Download citation
FormatBIBTeX
EndNote
RefMan
Refer
Medline
CIF
SGML
Plain Text
share
Next article

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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 66| Part 3| March 2010| Page o664
doi:10.1107/S1600536810006288

2-Amino-5-bromo­pyridinium 3-amino­benzoate

Madhukar Hemamalinia and Hoong-Kun Funa*‡

aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
*Correspondence e-mail: hkfun@usm.my

(Received 10 February 2010; accepted 17 February 2010; online 20 February 2010)

In the title salt, C5H6BrN2+·C7H6NO2−, the pyridine N atom of the 2-amino-5-bromo­pyridine mol­ecule is protonated. In the crystal, the protonated N atom and the 2-amino group are hydrogen-bonded to the carboxyl­ate O atoms via a pair of N—H⋯O hydrogen bonds, forming an R22(8) ring motif. Two inversion-related 3-amino­benzoate anions are linked through N—H⋯O hydrogen-bonds, forming an R22(14) ring motif. The crystal structure is further stabilized by π⋯π inter­actions involving the benzene and pyridinium rings with a centroid–centroid distance of 3.7743 (15) Å.

Related literature

For background to the chemistry of substituted pyridines, see: Pozharski et al. (1997[Pozharski, A. F., Soldatenkov, A. T. & Katritzky, A. R. (1997). Heterocycles in Life and Society. New York: Wiley.]); Katritzky et al. (1996[Katritzky, A. R., Rees, C. W. & Scriven, E. F. V. (1996). Comprehensive Heterocyclic Chemistry II. Oxford: Pergamon Press.]). Balasubramani & Fun (2009[Balasubramani, K. & Fun, H.-K. (2009). Acta Cryst. E65, o1729-o1730.]). For related structures, see: Goubitz et al. (2001[Goubitz, K., Sonneveld, E. J. & Schenk, H. (2001). Z. Kristallogr. 216, 176-181.]); Vaday & Foxman (1999[Vaday, S. & Foxman, M. B. (1999). Cryst. Eng. 2, 145-151.]). For details of 3-amino­benzoic acid, see: Windholz (1976[Windholz, M. (1976). The Merck Index, 9th ed. Boca Raton USA: Merck & Co. Inc.]); Voogd et al. (1980[Voogd, J., Verzijl, B. H. M. & Duisenberg, A. J. M. (1980). Acta Cryst. B36, 2805-2806.]). For details of hydrogen bonding, see: Jeffrey & Saenger (1991[Jeffrey, G. A. & Saenger, W. (1991). Hydrogen Bonding in Biological Structures. Berlin: Springer.]); Jeffrey (1997[Jeffrey, G. A. (1997). An Introduction to Hydrogen Bonding. Oxford University Press.]); Scheiner (1997[Scheiner, S. (1997). Hydrogen Bonding. A Theoretical Perspective. Oxford University Press.]). For hydrogen-bond motifs, see: Bernstein et al. (1995[Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555-1573.]).

[Scheme 1]

Experimental

Crystal data

  • C5H6BrN2+·C7H6NO2−

  • Mr = 309.15

  • Monoclinic, P 21 /c

  • a = 10.1650 (7) Å

  • b = 11.0431 (7) Å

  • c = 11.9550 (9) Å

  • β = 113.710 (2)°

  • V = 1228.71 (15) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 3.34 mm−1

  • T = 296 K

  • 0.42 × 0.39 × 0.11 mm
Data collection

  • Bruker APEX DUO CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2009[Bruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.332, Tmax = 0.708

  • 15251 measured reflections

  • 3565 independent reflections

  • 2650 reflections with I > 2σ(I)

  • Rint = 0.034
Refinement

  • R[F2 > 2σ(F2)] = 0.037

  • wR(F2) = 0.137

  • S = 1.06

  • 3565 reflections

  • 163 parameters

  • H-atom parameters constrained

  • Δρmax = 0.51 e Å−3

  • Δρmin = −0.54 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A D⋯A D—H⋯A
N1—H1⋯O1i 0.98 1.65 2.626 (3) 176
N2—H2A⋯O2i 0.86 1.99 2.826 (3) 165
N2—H2B⋯O1ii 0.86 2.06 2.909 (3) 170
N3—H3B⋯O2iii 0.86 2.26 3.028 (4) 148
Symmetry codes: (i) x, y-1, z-1; (ii) [x, -y+{\script{3\over 2}}, z-{\script{1\over 2}}]; (iii) -x, -y+2, -z+2.

Data collection: APEX2 (Bruker, 2009[Bruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2009[Bruker (2009). 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

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810006288/tk2628sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536810006288/tk2628Isup2.hkl

checkCIF report


Comment top

Pyridine and its derivatives play an important role in heterocyclic chemistry (Pozharski et al., 1997; Katritzky et al., 1996). They are often involved in hydrogen-bond interactions (Jeffrey & Saenger, 1991; Jeffrey, 1997; Scheiner, 1997). 3-Aminobenzoic acid is used as an intermediate for dyes and pesticides (Windholz, 1976). The crystal structures of 3-aminobenzoic acid (Voogd et al., 1980), 2-amino-5-bromopyridine (Goubitz et al., 2001) and 2-amino-5-bromopyridinium propynoate (Vaday & Foxman, 1999) have been reported in the literature. In order to study some interesting hydrogen bonding interactions, the synthesis and structure of the title salt, (I), is presented here.

The asymmetric unit of (I) (Fig. 1) contains a 2-amino-5-bromopyridinium cation and a 3-aminobenzoate anion, indicating that proton transfer has occurred during the co-crystallisation experiment. In the 2-amino-5-bromopyridinium cation, a wider than normal angle (C5—N1—C1 = 122.5 (2)°) is subtented at the protonated N1 atom. The 2-amino-5-methylpyridinium cation is essentially planar, with a maximum deviation of 0.020 (2)Å for atom N1.

In the crystal packing (Fig. 2), the protonated N1 atom and 2-amino group (N2) are hydrogen-bonded to the carboxylate oxygen atoms (O1 and O2) via a pair of N—H···O hydrogen bonds forming a ring motif R22(8) (Bernstein et al., 1995). Two inversion-related 3-aminobenzoate anions are linked through N3—H3B···O2 hydrogen-bonding to form a R22(14) ring motif (Table 1). This motif is also observed in the crystal structure of 2,3-diaminopyridinium 3-amino benzoate (Balasubramani & Fun, 2009). The crystal structure is further stabilized by a π···π stacking interaction between the pyridine rings (C1–C5/N1) and benzene ring (C6–C11) with a centroid- to-centroid distance of 3.7743 (15)Å [symmetry codes: 1-x, 1-y, 1-z].

Related literature top

For background to the chemistry of substituted pyridines, see: Pozharski et al. (1997); Katritzky et al. (1996). Balasubramani & Fun (2009). For related structures, see: Goubitz et al. (2001); Vaday & Foxman (1999). For details of 3-aminobenzoic acid, see: Windholz (1976); Voogd et al. (1980). For details of hydrogen bonding, see: Jeffrey & Saenger (1991); Jeffrey (1997); Scheiner (1997). For hydrogen-bond motifs, see: Bernstein et al. (1995).

Experimental top

A hot methanol solution (20 ml) of 2-amino-5-bromopyridine (87 mg, Aldrich) and 3-aminobenzoic acid (68 mg, Merck) were mixed and warmed over a heating magnetic stirrer for a few minutes. The resulting solution was allowed to cool slowly at room temperature and crystals of (I) appeared after a few days.

Refinement top

All hydrogen atoms were positioned geometrically [C–H = 0.93Å and N–H = 0.86–0.98Å] and were refined using a riding model, with Uiso(H) = 1.2 Ueq(C, N).

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); 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 asymmetric unit of (I) showing atom labelling scheme. Displacement ellipsoids are drawn at the 50% probability level.
[Figure 2] Fig. 2. The crystal packing of (I), showing hydrogen-bonded (dashed lines) networks.
2-Amino-5-bromopyridinium 3-aminobenzoate top
Crystal data top
C5H6BrN2+·C7H6NO2−F(000) = 620
Mr = 309.15Dx = 1.671 Mg m−3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 4215 reflections
a = 10.1650 (7) Åθ = 2.6–26.8°
b = 11.0431 (7) ŵ = 3.34 mm−1
c = 11.9550 (9) ÅT = 296 K
β = 113.710 (2)°Blcok, brown
V = 1228.71 (15) Å30.42 × 0.39 × 0.11 mm
Z = 4
Data collection top
Bruker APEX DUO CCD area-detector
diffractometer		3565 independent reflections
Radiation source: fine-focus sealed tube2650 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.034
ϕ and ω scansθmax = 30.0°, θmin = 2.2°
Absorption correction: multi-scan
(SADABS; Bruker, 2009)		h = −14→14
Tmin = 0.332, Tmax = 0.708k = −15→14
15251 measured reflectionsl = −16→16
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)] = 0.037Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.137H-atom parameters constrained
S = 1.06 w = 1/[σ2(Fo2) + (0.0846P)2 + 0.125P]
where P = (Fo2 + 2Fc2)/3
3565 reflections(Δ/σ)max = 0.001
163 parametersΔρmax = 0.51 e Å−3
0 restraintsΔρmin = −0.54 e Å−3
Crystal data top
C5H6BrN2+·C7H6NO2−V = 1228.71 (15) Å3
Mr = 309.15Z = 4
Monoclinic, P21/cMo Kα radiation
a = 10.1650 (7) ŵ = 3.34 mm−1
b = 11.0431 (7) ÅT = 296 K
c = 11.9550 (9) Å0.42 × 0.39 × 0.11 mm
β = 113.710 (2)°
Data collection top
Bruker APEX DUO CCD area-detector
diffractometer		3565 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2009)		2650 reflections with I > 2σ(I)
Tmin = 0.332, Tmax = 0.708Rint = 0.034
15251 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0370 restraints
wR(F2) = 0.137H-atom parameters constrained
S = 1.06Δρmax = 0.51 e Å−3
3565 reflectionsΔρmin = −0.54 e Å−3
163 parameters
Special details top

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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
Br10.82844 (3)0.52926 (3)0.04268 (3)0.05749 (15)
N10.5198 (2)0.30649 (19)0.06832 (17)0.0383 (4)
N20.4208 (3)0.2756 (2)0.2082 (2)0.0499 (5)
H2A0.37150.21680.16380.060*
H2B0.41250.29400.27490.060*
C10.5087 (2)0.3373 (2)0.1739 (2)0.0378 (5)
C20.5959 (3)0.4328 (3)0.2429 (2)0.0442 (5)
H20.58970.45690.31510.053*
C30.6892 (3)0.4899 (2)0.2043 (3)0.0448 (5)
H30.74690.55250.25020.054*
C40.6971 (2)0.4537 (2)0.0954 (2)0.0387 (5)
C50.6125 (2)0.3619 (2)0.0294 (2)0.0387 (5)
H50.61830.3370−0.04280.046*
O10.3733 (2)1.13481 (18)0.91776 (17)0.0528 (5)
O20.2423 (2)1.11501 (19)1.02651 (17)0.0549 (5)
N3−0.0679 (3)0.7483 (2)0.8606 (3)0.0677 (7)
H3A−0.11180.68650.81820.081*
H3B−0.09010.77460.91850.081*
C60.2439 (3)0.9284 (2)0.7774 (2)0.0426 (5)
H60.31150.96930.75760.051*
C70.1775 (3)0.8250 (3)0.7134 (2)0.0477 (6)
H70.20120.79630.65080.057*
C80.0755 (3)0.7644 (2)0.7426 (2)0.0461 (6)
H80.03150.69540.69920.055*
C90.0388 (3)0.8058 (2)0.8355 (2)0.0445 (5)
C100.1058 (3)0.9094 (2)0.9004 (2)0.0412 (5)
H100.08200.93800.96300.049*
C110.2085 (3)0.9701 (2)0.8712 (2)0.0375 (5)
C120.2807 (3)1.0815 (2)0.9441 (2)0.0399 (5)
H10.46170.24390.01290.048*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br10.0532 (2)0.0605 (2)0.0637 (2)−0.01495 (12)0.02867 (15)−0.00314 (12)
N10.0453 (10)0.0357 (10)0.0354 (9)−0.0041 (8)0.0179 (8)−0.0056 (8)
N20.0630 (14)0.0513 (13)0.0451 (11)−0.0075 (10)0.0320 (10)−0.0064 (10)
C10.0432 (11)0.0364 (12)0.0346 (10)0.0035 (9)0.0165 (8)−0.0018 (9)
C20.0519 (13)0.0432 (13)0.0391 (12)0.0008 (11)0.0200 (10)−0.0102 (10)
C30.0454 (13)0.0388 (12)0.0480 (13)−0.0018 (10)0.0167 (10)−0.0113 (10)
C40.0357 (11)0.0374 (12)0.0438 (12)−0.0006 (8)0.0168 (9)−0.0014 (9)
C50.0427 (11)0.0401 (13)0.0356 (11)−0.0004 (9)0.0183 (9)−0.0031 (9)
O10.0679 (12)0.0533 (12)0.0469 (10)−0.0214 (9)0.0332 (9)−0.0119 (8)
O20.0784 (13)0.0500 (11)0.0479 (10)−0.0120 (9)0.0376 (10)−0.0104 (8)
N30.0686 (16)0.0571 (16)0.094 (2)−0.0195 (13)0.0496 (15)−0.0166 (15)
C60.0455 (12)0.0433 (13)0.0412 (12)−0.0013 (10)0.0196 (9)−0.0006 (10)
C70.0490 (13)0.0480 (15)0.0467 (13)0.0038 (11)0.0198 (10)−0.0063 (11)
C80.0443 (13)0.0380 (13)0.0508 (14)0.0026 (10)0.0137 (10)−0.0052 (11)
C90.0384 (11)0.0407 (13)0.0546 (14)0.0005 (9)0.0191 (10)0.0024 (11)
C100.0430 (12)0.0389 (13)0.0457 (12)0.0005 (9)0.0221 (10)0.0008 (10)
C110.0422 (11)0.0334 (12)0.0353 (11)0.0024 (8)0.0139 (9)0.0034 (9)
C120.0493 (13)0.0365 (12)0.0336 (10)−0.0017 (9)0.0163 (9)0.0021 (9)
Geometric parameters (Å, º) top
Br1—C41.885 (2)O2—C121.252 (3)
N1—C51.353 (3)N3—C91.390 (3)
N1—C11.355 (3)N3—H3A0.8600
N1—H10.9745N3—H3B0.8600
N2—C11.313 (3)C6—C111.387 (3)
N2—H2A0.8600C6—C71.389 (4)
N2—H2B0.8600C6—H60.9300
C1—C21.410 (4)C7—C81.391 (4)
C2—C31.365 (4)C7—H70.9300
C2—H20.9300C8—C91.384 (4)
C3—C41.395 (4)C8—H80.9300
C3—H30.9300C9—C101.396 (4)
C4—C51.358 (3)C10—C111.398 (3)
C5—H50.9300C10—H100.9300
O1—C121.254 (3)C11—C121.515 (3)
C5—N1—C1122.5 (2)H3A—N3—H3B120.0
C5—N1—H1113.7C11—C6—C7119.5 (2)
C1—N1—H1123.8C11—C6—H6120.3
C1—N2—H2A120.0C7—C6—H6120.3
C1—N2—H2B120.0C6—C7—C8120.2 (2)
H2A—N2—H2B120.0C6—C7—H7119.9
N2—C1—N1118.8 (2)C8—C7—H7119.9
N2—C1—C2123.5 (2)C9—C8—C7120.8 (2)
N1—C1—C2117.7 (2)C9—C8—H8119.6
C3—C2—C1120.4 (2)C7—C8—H8119.6
C3—C2—H2119.8C8—C9—N3120.6 (2)
C1—C2—H2119.8C8—C9—C10119.2 (2)
C2—C3—C4119.5 (2)N3—C9—C10120.2 (2)
C2—C3—H3120.3C9—C10—C11120.1 (2)
C4—C3—H3120.3C9—C10—H10120.0
C5—C4—C3119.7 (2)C11—C10—H10120.0
C5—C4—Br1120.33 (18)C6—C11—C10120.3 (2)
C3—C4—Br1119.97 (19)C6—C11—C12120.8 (2)
N1—C5—C4120.3 (2)C10—C11—C12118.9 (2)
N1—C5—H5119.9O2—C12—O1124.2 (2)
C4—C5—H5119.9O2—C12—C11117.4 (2)
C9—N3—H3A120.0O1—C12—C11118.4 (2)
C9—N3—H3B120.0
C5—N1—C1—N2−177.0 (2)C7—C8—C9—N3176.9 (3)
C5—N1—C1—C21.5 (3)C7—C8—C9—C10−0.2 (4)
N2—C1—C2—C3177.4 (3)C8—C9—C10—C110.0 (4)
N1—C1—C2—C3−1.0 (4)N3—C9—C10—C11−177.1 (3)
C1—C2—C3—C40.4 (4)C7—C6—C11—C10−0.7 (4)
C2—C3—C4—C5−0.2 (4)C7—C6—C11—C12179.1 (2)
C2—C3—C4—Br1−178.6 (2)C9—C10—C11—C60.4 (4)
C1—N1—C5—C4−1.3 (4)C9—C10—C11—C12−179.3 (2)
C3—C4—C5—N10.7 (4)C6—C11—C12—O2179.1 (2)
Br1—C4—C5—N1178.99 (18)C10—C11—C12—O2−1.2 (3)
C11—C6—C7—C80.5 (4)C6—C11—C12—O1−0.2 (4)
C6—C7—C8—C9−0.1 (4)C10—C11—C12—O1179.5 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O1i0.981.652.626 (3)176
N2—H2A···O2i0.861.992.826 (3)165
N2—H2B···O1ii0.862.062.909 (3)170
N3—H3B···O2iii0.862.263.028 (4)148
Symmetry codes: (i) x, y−1, z−1; (ii) x, −y+3/2, z−1/2; (iii) −x, −y+2, −z+2.

Experimental details

Crystal data
Chemical formulaC5H6BrN2+·C7H6NO2−
Mr309.15
Crystal system, space groupMonoclinic, P21/c
Temperature (K)296
a, b, c (Å)10.1650 (7), 11.0431 (7), 11.9550 (9)
β (°) 113.710 (2)
V (Å3)1228.71 (15)
Z4
Radiation typeMo Kα
µ (mm−1)3.34
Crystal size (mm)0.42 × 0.39 × 0.11
Data collection
DiffractometerBruker APEX DUO CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2009)
Tmin, Tmax0.332, 0.708
No. of measured, independent and
observed [I > 2σ(I)] reflections		15251, 3565, 2650
Rint0.034
(sin θ/λ)max (Å−1)0.703
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.037, 0.137, 1.06
No. of reflections3565
No. of parameters163
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å−3)0.51, −0.54

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

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O1i0.98001.65002.626 (3)176.00
N2—H2A···O2i0.86001.99002.826 (3)165.00
N2—H2B···O1ii0.86002.06002.909 (3)170.00
N3—H3B···O2iii0.86002.26003.028 (4)148.00
Symmetry codes: (i) x, y−1, z−1; (ii) x, −y+3/2, z−1/2; (iii) −x, −y+2, −z+2.
 

Footnotes

‡Thomson Reuters ResearcherID: A-3561-2009.

Acknowledgements

MH and HKF thank the Malaysian Government and Universiti Sains Malaysia for the Research University Golden Goose grant No. 1001/PFIZIK/811012. MH thanks Universiti Sains Malaysia for a post-doctoral research fellowship.

References

First citationBalasubramani, K. & Fun, H.-K. (2009). Acta Cryst. E65, o1729–o1730.  Web of Science CSD CrossRef IUCr Journals 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 citationBruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
 First citationGoubitz, K., Sonneveld, E. J. & Schenk, H. (2001). Z. Kristallogr. 216, 176–181.  Web of Science CSD CrossRef CAS Google Scholar
 First citationJeffrey, G. A. (1997). An Introduction to Hydrogen Bonding. Oxford University Press.  Google Scholar
 First citationJeffrey, G. A. & Saenger, W. (1991). Hydrogen Bonding in Biological Structures. Berlin: Springer.  Google Scholar
 First citationKatritzky, A. R., Rees, C. W. & Scriven, E. F. V. (1996). Comprehensive Heterocyclic Chemistry II. Oxford: Pergamon Press.  Google Scholar
 First citationPozharski, A. F., Soldatenkov, A. T. & Katritzky, A. R. (1997). Heterocycles in Life and Society. New York: Wiley.  Google Scholar
 First citationScheiner, S. (1997). Hydrogen Bonding. A Theoretical Perspective. Oxford University Press.  Google Scholar
 First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
 First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals Google Scholar
 First citationVaday, S. & Foxman, M. B. (1999). Cryst. Eng. 2, 145–151.  CSD CrossRef CAS Google Scholar
 First citationVoogd, J., Verzijl, B. H. M. & Duisenberg, A. J. M. (1980). Acta Cryst. B36, 2805–2806.  CSD CrossRef CAS IUCr Journals Web of Science Google Scholar
 First citationWindholz, M. (1976). The Merck Index, 9th ed. Boca Raton USA: Merck & Co. Inc.  Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 66| Part 3| March 2010| Page o664
doi:10.1107/S1600536810006288
Follow Acta Cryst. E
Sign up for e-alerts
E-alerts
Follow Acta Cryst. on Twitter
Twitter
Follow us on facebook
Facebook
Sign up for RSS feeds
RSS