PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of actaeInternational Union of Crystallographysearchopen accessarticle submissionjournal home pagethis article
 
Acta Crystallogr Sect E Struct Rep Online. 2010 November 1; 66(Pt 11): o2950–o2951.
Published online 2010 October 30. doi:  10.1107/S1600536810042571
PMCID: PMC3009185

2-Isopropyl-6-methyl-4-oxo-3,4-dihydro­pyrimidin-1-ium 2-carb­oxy-4,6-dinitro­phenolate monohydrate

Abstract

In the title mol­ecular salt, C8H13N2O+·C7H3N2O7 ·H2O, the pyrimidinium cation is essentially planar, with a maximum deviation of 0.009 (1) Å. The cation undergoes an enol–keto tautomerism during the crystallization. In the crystal, the ion pairs and water mol­ecules are connected via O—H(...)O, N—H(...)O and C—H(...)O hydrogen bonds, forming two-dimensional networks parallel to the bc plane. There is an intra­molecular O—H(...)O hydrogen bond in the 3,5-dinitro­salicylate anion, which generates an S(6) ring motif.

Related literature

For applications of pyrimidine derivaties, see: Condon et al. (1993 [triangle]); Maeno et al. (1990 [triangle]); Gilchrist (1997 [triangle]). For a related structure, see: Hemamalini & Fun (2010 [triangle]). For hydrogen-bond motifs, see: Bernstein et al. (1995 [triangle]). For bond-length data, see: Allen et al. (1987 [triangle]). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-66-o2950-scheme1.jpg

Experimental

Crystal data

  • C8H13N2O+·C7H3N2O7 ·H2O
  • M r = 398.33
  • Triclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-o2950-efi1.jpg
  • a = 6.6691 (3) Å
  • b = 11.3831 (4) Å
  • c = 12.2900 (5) Å
  • α = 89.727 (2)°
  • β = 76.771 (2)°
  • γ = 76.930 (2)°
  • V = 883.62 (6) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 0.13 mm−1
  • T = 100 K
  • 0.52 × 0.13 × 0.10 mm

Data collection

  • Bruker SMART APEXII CCD area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Bruker, 2009 [triangle]) T min = 0.937, T max = 0.987
  • 17014 measured reflections
  • 4061 independent reflections
  • 3279 reflections with I > 2σ(I)
  • R int = 0.030

Refinement

  • R[F 2 > 2σ(F 2)] = 0.040
  • wR(F 2) = 0.105
  • S = 1.03
  • 4061 reflections
  • 273 parameters
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.53 e Å−3
  • Δρmin = −0.30 e Å−3

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

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810042571/fj2355sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810042571/fj2355Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

MH and HKF thank the Malaysian Government and Universiti Sains Malaysia for the Research University grant No. 1001/PFIZIK/811160. MH also thanks Universiti Sains Malaysia for a post-doctoral research fellowship.

supplementary crystallographic information

Comment

Pyrimidine derivatives are very important molecules in biology and have many application in the areas of pesticide and pharmaceutical agents (Condon et al., 1993). For example, imazosulfuron, ethirmol and mepanipyrim have been commercialized as agrochemicals (Maeno et al., 1990). Pyrimidine derivatives have also been developed as antiviral agents, such as AZT, which is the most widely-used anti-AIDS drug (Gilchrist, 1997). The nitro-substituted aromatic acid 3,5-dinitrosalicylic acid (DNSA) has proven potential for formation of proton-transfer compounds, particularly because of its acid strength (pKa = 2.18), its interactive ortho-related phenolic substituent group together with the nitro substituents which have potential for both π···π interactions as well as hydrogen-bonding interactions. Since our aim is to study some interesting hydrogen bonding interactions, the crystal structure of the title compound is presented here.

The asymmetric unit of (I) (Fig 1), contains a 2-isopropyl-6-methyl pyrimidinium-4(3H)-one cation, a 3,5-dinitrosalicylate anion and a water molecule. In the cation, the proton transfer from the hydroxyl group of the anion to the N4 atom leads to a slight increase in the C8—N4—C11 angle to 124.54 (12)°, compared to 116.83 (8)° in (Hemamalini & Fun, 2010). The phenol oxygen atoms are bent slightly away from the mean plane of the benzene ring [torsion angle O1-C7-C8-C9 = 177.02 (13)°]. The Pyrimidine ring is essentially planar, with a maximum deviation of 0.009 (1) Å for atom N4. The bond lengths (Allen et al., 1987) and angles are normal. The cation undergoes an enol-keto tautomerism during the crystallization. Similar tautomerism was also observed in the crystal structure of 2-Isopropyl-6-methylpyrimidinium-4(3H)-one (Hemamalini & Fun, 2010).

In the crystals structure (Fig. 2), the ion pairs and water molecules are connected via N3—H1N3···O6, N4—H1N4···O1W, O1W—H2W1···O1, O1W—H1W1···O3, C9—H9A···O5, C12—H12A···O7, C14—H14B···O4 and C15—H15C···O3 hydrogen bonds, forming two-dimensional networks parallel to the bc plane. There is an intramolecular O7—H7···O1 hydrogen bond in the 3,5-dinitrosalicylate anion which generates an S(6) (Bernstein et al., 1995) ring motif.

Experimental

A hot methanol solution (20 ml) of 2-isopropyl-4-hydroxy-6-methylpyrimidine (46 mg, Aldrich) and 3,5-dinitrosalicylic acid (58 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 yellow blocks of (I) appeared after a few days.

Refinement

Atoms H1N3, H1N4, H2W1 and H1W1 were located from a difference Fourier map and were refined freely [N–H = 0.90 (2)– 0.91 (2) Å and O–H = 0.82–0.85 (2) Å]. The remaining hydrogen atoms were positioned geometrically [C–H = 0.93 or 0.96 Å] and were refined using a riding model, with Uiso(H) = 1.2 or 1.5 Ueq(C,O). A rotating group model was used for the methyl group.

Figures

Fig. 1.
The asymmetric unit of the title compound. Displacement ellipsoids are drawn at the 50% probability level.
Fig. 2.
The crystal packing of the title compound, showing hydrogen-bonded (dashed lines) networks. H atoms not involved in the interactions have been omitted for clarity.

Crystal data

C8H13N2O+·C7H3N2O7·H2OZ = 2
Mr = 398.33F(000) = 416
Triclinic, P1Dx = 1.497 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 6.6691 (3) ÅCell parameters from 6994 reflections
b = 11.3831 (4) Åθ = 2.4–31.6°
c = 12.2900 (5) ŵ = 0.13 mm1
α = 89.727 (2)°T = 100 K
β = 76.771 (2)°Block, yellow
γ = 76.930 (2)°0.52 × 0.13 × 0.10 mm
V = 883.62 (6) Å3

Data collection

Bruker SMART APEXII CCD area-detector diffractometer4061 independent reflections
Radiation source: fine-focus sealed tube3279 reflections with I > 2σ(I)
graphiteRint = 0.030
[var phi] and ω scansθmax = 27.5°, θmin = 1.7°
Absorption correction: multi-scan (SADABS; Bruker, 2009)h = −8→8
Tmin = 0.937, Tmax = 0.987k = −14→12
17014 measured reflectionsl = −15→15

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.040Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.105H atoms treated by a mixture of independent and constrained refinement
S = 1.03w = 1/[σ2(Fo2) + (0.0477P)2 + 0.3946P] where P = (Fo2 + 2Fc2)/3
4061 reflections(Δ/σ)max < 0.001
273 parametersΔρmax = 0.53 e Å3
0 restraintsΔρmin = −0.30 e Å3

Special details

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

xyzUiso*/Ueq
O10.30537 (18)−0.17099 (10)0.14974 (9)0.0223 (2)
O20.5667 (2)−0.35714 (10)0.01344 (10)0.0310 (3)
O30.4865 (2)−0.36692 (10)−0.14689 (10)0.0308 (3)
O40.36257 (17)−0.00307 (10)−0.33888 (9)0.0231 (3)
O50.23770 (18)0.16989 (10)−0.24573 (9)0.0251 (3)
O60.07237 (17)0.19149 (9)0.16326 (9)0.0200 (2)
O70.14505 (18)0.02269 (10)0.25242 (9)0.0213 (2)
H70.1960−0.04930.23600.032*
O80.31892 (18)0.38518 (9)0.41955 (9)0.0220 (2)
N10.30166 (19)0.05932 (11)−0.25097 (10)0.0182 (3)
N20.4862 (2)−0.31082 (11)−0.06121 (11)0.0206 (3)
N30.11901 (19)0.64262 (11)0.66450 (10)0.0148 (3)
N40.23843 (18)0.58272 (10)0.47925 (10)0.0144 (3)
C10.3103 (2)−0.11927 (13)0.05577 (12)0.0151 (3)
C20.3897 (2)−0.18173 (13)−0.05146 (12)0.0156 (3)
C30.3840 (2)−0.12442 (13)−0.15046 (12)0.0158 (3)
H3A0.4330−0.1682−0.21880.019*
C40.3044 (2)−0.00117 (13)−0.14625 (12)0.0153 (3)
C50.2283 (2)0.06623 (13)−0.04535 (12)0.0150 (3)
H5A0.17740.1494−0.04460.018*
C60.2289 (2)0.00879 (13)0.05385 (12)0.0139 (3)
C70.1427 (2)0.08136 (13)0.16144 (12)0.0157 (3)
C80.2598 (2)0.45827 (13)0.49893 (12)0.0158 (3)
C90.2071 (2)0.43350 (13)0.61585 (12)0.0159 (3)
H9A0.22140.35380.63640.019*
C100.1374 (2)0.52333 (13)0.69601 (12)0.0159 (3)
C110.1694 (2)0.67070 (13)0.55878 (12)0.0142 (3)
C120.1447 (2)0.80024 (12)0.52940 (12)0.0151 (3)
H12A0.10790.85010.59900.018*
C13−0.0376 (2)0.83580 (14)0.47027 (14)0.0221 (3)
H13A−0.16540.82270.51810.033*
H13B−0.00480.78740.40200.033*
H13C−0.05680.91950.45370.033*
C140.3510 (2)0.82287 (13)0.45724 (13)0.0192 (3)
H14A0.46280.79800.49550.029*
H14B0.33310.90730.44380.029*
H14C0.38640.77740.38710.029*
C150.0772 (3)0.50606 (14)0.81836 (13)0.0215 (3)
H15A0.09650.42140.83100.032*
H15B−0.06860.54590.84740.032*
H15C0.16470.53980.85550.032*
O1W0.3284 (2)0.60970 (11)0.25362 (10)0.0271 (3)
H1N30.066 (3)0.7030 (18)0.7187 (16)0.028 (5)*
H1N40.271 (3)0.5992 (18)0.4063 (17)0.032 (5)*
H2W10.339 (3)0.667 (2)0.2096 (17)0.035 (5)*
H1W10.377 (4)0.544 (2)0.2154 (19)0.044 (6)*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.0296 (6)0.0173 (5)0.0173 (5)−0.0039 (5)−0.0015 (4)0.0032 (4)
O20.0424 (7)0.0207 (6)0.0229 (6)0.0050 (5)−0.0056 (5)0.0036 (5)
O30.0487 (8)0.0171 (6)0.0231 (6)−0.0034 (5)−0.0054 (5)−0.0076 (5)
O40.0289 (6)0.0268 (6)0.0137 (5)−0.0082 (5)−0.0031 (4)−0.0002 (5)
O50.0344 (6)0.0173 (6)0.0230 (6)−0.0043 (5)−0.0075 (5)0.0060 (5)
O60.0244 (6)0.0138 (5)0.0183 (5)−0.0014 (4)−0.0006 (4)−0.0027 (4)
O70.0287 (6)0.0153 (5)0.0149 (5)−0.0002 (5)0.0004 (4)−0.0004 (4)
O80.0323 (6)0.0137 (5)0.0175 (6)−0.0029 (5)−0.0031 (5)−0.0019 (4)
N10.0184 (6)0.0198 (7)0.0179 (7)−0.0074 (5)−0.0047 (5)0.0035 (5)
N20.0240 (7)0.0153 (6)0.0186 (7)−0.0035 (5)0.0018 (5)0.0001 (5)
N30.0166 (6)0.0122 (6)0.0140 (6)−0.0024 (5)−0.0017 (5)−0.0006 (5)
N40.0171 (6)0.0116 (6)0.0130 (6)−0.0026 (5)−0.0013 (5)0.0010 (5)
C10.0136 (7)0.0169 (7)0.0151 (7)−0.0059 (5)−0.0014 (5)0.0016 (6)
C20.0161 (7)0.0122 (7)0.0174 (7)−0.0032 (5)−0.0020 (5)−0.0006 (5)
C30.0166 (7)0.0179 (7)0.0137 (7)−0.0072 (6)−0.0016 (5)−0.0019 (6)
C40.0152 (7)0.0195 (7)0.0130 (7)−0.0076 (6)−0.0032 (5)0.0034 (6)
C50.0132 (7)0.0135 (7)0.0186 (7)−0.0046 (5)−0.0028 (5)0.0008 (6)
C60.0116 (6)0.0149 (7)0.0151 (7)−0.0043 (5)−0.0014 (5)−0.0007 (5)
C70.0134 (7)0.0169 (7)0.0159 (7)−0.0047 (5)−0.0003 (5)−0.0009 (6)
C80.0156 (7)0.0132 (7)0.0182 (7)−0.0028 (5)−0.0035 (5)0.0004 (6)
C90.0178 (7)0.0112 (7)0.0181 (7)−0.0030 (5)−0.0036 (6)0.0036 (6)
C100.0147 (7)0.0157 (7)0.0175 (7)−0.0039 (6)−0.0041 (5)0.0033 (6)
C110.0117 (6)0.0143 (7)0.0163 (7)−0.0028 (5)−0.0027 (5)−0.0001 (5)
C120.0183 (7)0.0105 (7)0.0154 (7)−0.0033 (5)−0.0019 (5)−0.0001 (5)
C130.0222 (8)0.0136 (7)0.0319 (9)−0.0033 (6)−0.0099 (7)0.0055 (6)
C140.0203 (7)0.0138 (7)0.0221 (8)−0.0051 (6)−0.0008 (6)0.0007 (6)
C150.0267 (8)0.0189 (8)0.0176 (8)−0.0048 (6)−0.0031 (6)0.0021 (6)
O1W0.0475 (8)0.0128 (6)0.0158 (6)−0.0038 (5)−0.0005 (5)0.0009 (5)

Geometric parameters (Å, °)

O1—C11.2909 (17)C5—C61.3811 (19)
O2—N21.2250 (17)C5—H5A0.9300
O3—N21.2334 (17)C6—C71.486 (2)
O4—N11.2299 (16)C8—C91.441 (2)
O5—N11.2311 (16)C9—C101.348 (2)
O6—C71.2335 (17)C9—H9A0.9300
O7—C71.3010 (17)C10—C151.489 (2)
O7—H70.8200C11—C121.4981 (19)
O8—C81.2177 (18)C12—C141.5314 (19)
N1—C41.4586 (18)C12—C131.533 (2)
N2—C21.4581 (18)C12—H12A0.9800
N3—C111.3221 (18)C13—H13A0.9600
N3—C101.3965 (18)C13—H13B0.9600
N3—H1N30.91 (2)C13—H13C0.9600
N4—C111.3285 (19)C14—H14A0.9600
N4—C81.4166 (18)C14—H14B0.9600
N4—H1N40.90 (2)C14—H14C0.9600
C1—C21.429 (2)C15—H15A0.9600
C1—C61.438 (2)C15—H15B0.9600
C2—C31.382 (2)C15—H15C0.9600
C3—C41.380 (2)O1W—H2W10.85 (2)
C3—H3A0.9300O1W—H1W10.84 (2)
C4—C51.389 (2)
C7—O7—H7109.5N4—C8—C9113.61 (12)
O4—N1—O5124.05 (12)C10—C9—C8121.41 (13)
O4—N1—C4118.14 (12)C10—C9—H9A119.3
O5—N1—C4117.81 (12)C8—C9—H9A119.3
O2—N2—O3123.54 (13)C9—C10—N3118.94 (13)
O2—N2—C2119.12 (12)C9—C10—C15124.98 (13)
O3—N2—C2117.31 (12)N3—C10—C15116.08 (13)
C11—N3—C10122.35 (13)N3—C11—N4119.11 (13)
C11—N3—H1N3119.1 (12)N3—C11—C12120.22 (13)
C10—N3—H1N3118.5 (12)N4—C11—C12120.66 (12)
C11—N4—C8124.54 (12)C11—C12—C14111.37 (12)
C11—N4—H1N4121.1 (12)C11—C12—C13109.34 (11)
C8—N4—H1N4114.3 (12)C14—C12—C13111.33 (12)
O1—C1—C2124.18 (13)C11—C12—H12A108.2
O1—C1—C6120.48 (13)C14—C12—H12A108.2
C2—C1—C6115.33 (12)C13—C12—H12A108.2
C3—C2—C1122.73 (13)C12—C13—H13A109.5
C3—C2—N2116.52 (13)C12—C13—H13B109.5
C1—C2—N2120.74 (12)H13A—C13—H13B109.5
C4—C3—C2118.90 (13)C12—C13—H13C109.5
C4—C3—H3A120.5H13A—C13—H13C109.5
C2—C3—H3A120.5H13B—C13—H13C109.5
C3—C4—C5121.76 (13)C12—C14—H14A109.5
C3—C4—N1118.76 (13)C12—C14—H14B109.5
C5—C4—N1119.48 (13)H14A—C14—H14B109.5
C6—C5—C4119.48 (13)C12—C14—H14C109.5
C6—C5—H5A120.3H14A—C14—H14C109.5
C4—C5—H5A120.3H14B—C14—H14C109.5
C5—C6—C1121.77 (13)C10—C15—H15A109.5
C5—C6—C7119.05 (13)C10—C15—H15B109.5
C1—C6—C7119.18 (12)H15A—C15—H15B109.5
O6—C7—O7122.30 (13)C10—C15—H15C109.5
O6—C7—C6121.12 (13)H15A—C15—H15C109.5
O7—C7—C6116.58 (12)H15B—C15—H15C109.5
O8—C8—N4119.20 (13)H2W1—O1W—H1W1108 (2)
O8—C8—C9127.19 (13)
O1—C1—C2—C3177.02 (13)O1—C1—C6—C71.1 (2)
C6—C1—C2—C3−1.7 (2)C2—C1—C6—C7179.94 (12)
O1—C1—C2—N2−4.3 (2)C5—C6—C7—O6−0.5 (2)
C6—C1—C2—N2176.93 (12)C1—C6—C7—O6179.66 (13)
O2—N2—C2—C3153.14 (14)C5—C6—C7—O7179.34 (12)
O3—N2—C2—C3−24.99 (19)C1—C6—C7—O7−0.53 (19)
O2—N2—C2—C1−25.6 (2)C11—N4—C8—O8177.87 (13)
O3—N2—C2—C1156.26 (13)C11—N4—C8—C9−2.37 (19)
C1—C2—C3—C42.0 (2)O8—C8—C9—C10−178.07 (15)
N2—C2—C3—C4−176.69 (12)N4—C8—C9—C102.18 (19)
C2—C3—C4—C5−0.6 (2)C8—C9—C10—N3−0.8 (2)
C2—C3—C4—N1179.06 (12)C8—C9—C10—C15179.28 (13)
O4—N1—C4—C32.98 (19)C11—N3—C10—C9−0.6 (2)
O5—N1—C4—C3−177.24 (13)C11—N3—C10—C15179.26 (13)
O4—N1—C4—C5−177.33 (12)C10—N3—C11—N40.5 (2)
O5—N1—C4—C52.45 (19)C10—N3—C11—C12179.41 (12)
C3—C4—C5—C6−1.0 (2)C8—N4—C11—N31.1 (2)
N1—C4—C5—C6179.34 (12)C8—N4—C11—C12−177.78 (12)
C4—C5—C6—C11.2 (2)N3—C11—C12—C14126.27 (14)
C4—C5—C6—C7−178.63 (12)N4—C11—C12—C14−54.87 (17)
O1—C1—C6—C5−178.73 (13)N3—C11—C12—C13−110.27 (15)
C2—C1—C6—C50.07 (19)N4—C11—C12—C1368.59 (17)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N3—H1N3···O6i0.91 (2)1.817 (19)2.7180 (16)170 (2)
N4—H1N4···O1W0.90 (2)1.84 (2)2.7309 (17)171 (2)
O1W—H2W1···O1ii0.85 (2)1.97 (2)2.7878 (16)162 (2)
O1W—H1W1···O3iii0.84 (2)2.11 (2)2.9381 (17)170 (2)
O7—H7···O10.821.672.4370 (16)156
C9—H9A···O5iv0.932.543.4312 (18)161
C12—H12A···O7i0.982.413.3023 (18)152
C14—H14B···O4v0.962.603.2318 (19)124
C15—H15C···O3vi0.962.603.471 (2)152

Symmetry codes: (i) −x, −y+1, −z+1; (ii) x, y+1, z; (iii) −x+1, −y, −z; (iv) x, y, z+1; (v) −x+1, −y+1, −z; (vi) x, y+1, z+1.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: FJ2355).

References

  • Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1–19.
  • Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl.34, 1555–1573.
  • Bruker (2009). APEX2, SAINT and SADABS Bruker AXS Inc., Madison, Wisconsin, USA.
  • Condon, M. E., Brady, T. E., Feist, D., Malefyt, T., Marc, P., Quakenbush, L. S., Rodaway, S. J., Shaner, D. L. & Tecle, B. (1993). Brighton Crop Protection Conference on Weeds, pp. 41–46. Alton, Hampshire, England: BCPC Publications.
  • Cosier, J. & Glazer, A. M. (1986). J. Appl. Cryst.19, 105–107.
  • Gilchrist, T. L. (1997). Heterocyclic Chemistry, 3rd ed., pp. 261–276. Singapore: Addison Wesley Longman.
  • Hemamalini, M. & Fun, H.-K. (2010). Acta Cryst. E66, o2459. [PMC free article] [PubMed]
  • Maeno, S., Miura, I., Masuda, K. & Nagata, T. (1990). Brighton Crop Protection Conference on Pests and Diseases, pp. 415–422. Alton, Hampshire, England: BCPC Publications.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Spek, A. L. (2009). Acta Cryst. D65, 148–155. [PMC free article] [PubMed]

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography