PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of actaeInternational Union of Crystallographysearchopen accessarticle submissionjournal home pagethis article
 
Acta Crystallogr Sect E Struct Rep Online. 2009 December 1; 65(Pt 12): o3041–o3042.
Published online 2009 November 7. doi:  10.1107/S1600536809045760
PMCID: PMC2971850

1,5-Dimethyl-3-oxo-2-phenyl-2,3-di­hy­dro-1H-pyrazol-4-aminium 2-hydroxy­benzoate

Abstract

In the title salt, C11H14N3O+·C7H5O3 , the phenyl ring of the cation is oriented at an angle of 67.0 (1)° with respect to the five-membered pyrazolone ring. The carboxyl­ate plane of the anion is twisted out from the plane of the aromatic ring at an angle of 13.7 (3)°. In the crystal, the cations form hydrogen-bonded dimers with an R 2 2(10) ring motif. The salicylate anion has an intra­molecular O—H(...)O hydrogen bond.

Related literature

For the biological and pharmacological importance of pyrazolone derivatives and 4-amino­anti­pyrene compounds, see: Filho et al. (1998 [triangle]); Jain et al. (2003 [triangle]); Mishra (1999 [triangle]); Sondhi et al. (1999 [triangle]); Sondhi et al. (2001 [triangle]). For similar hydrogen-bonded structures, see: Athimoolam & Natarajan (2006a [triangle],b [triangle],c [triangle]); Athimoolam & Rajaram (2005 [triangle]). For hydrogen bonding inter­actions and graph-set notations, see: Desiraju (1989 [triangle]); Etter et al. (1990 [triangle]). For a description of the Cambridge Structural Database, see: Allen (2002 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-65-o3041-scheme1.jpg

Experimental

Crystal data

  • C11H14N3O+·C7H5O3
  • M r = 341.36
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-65-o3041-efi4.jpg
  • a = 8.3182 (6) Å
  • b = 23.3006 (16) Å
  • c = 8.8503 (6) Å
  • β = 101.517 (1)°
  • V = 1680.8 (2) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.10 mm−1
  • T = 293 K
  • 0.24 × 0.13 × 0.12 mm

Data collection

  • Bruker SMART APEX CCD area-detector diffractometer
  • Absorption correction: none
  • 16025 measured reflections
  • 2959 independent reflections
  • 2599 reflections with I > 2σ(I)
  • R int = 0.020

Refinement

  • R[F 2 > 2σ(F 2)] = 0.041
  • wR(F 2) = 0.113
  • S = 1.05
  • 2959 reflections
  • 229 parameters
  • H-atom parameters constrained
  • Δρmax = 0.18 e Å−3
  • Δρmin = −0.18 e Å−3

Data collection: SMART (Bruker, 2001 [triangle]); cell refinement: SAINT (Bruker, 2001 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXTL/PC (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXTL/PC; molecular graphics: Mercury (Macrae et al., 2006 [triangle] ) and PLATON (Spek, 2009 [triangle]); software used to prepare material for publication: SHELXTL/PC.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809045760/bt5124sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809045760/bt5124Isup2.hkl

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

Acknowledgments

SAB sincerely thanks the Vice-Chancellor and Management of Kalasalingam University, Anand Nagar, Krishnan Koil, for their support and encouragement. SA thanks the Vice-Chancellor of Anna University Tirunelveli for his support and encouragement.

supplementary crystallographic information

Comment

4-Aminoantipyrene, which contain pyrazolone ring, is an important compound in the class analgesic agent in otic solutions in combination with other analgesic such as benzocaine and phenylephrine. Pyrazolone is a five-membered lactam ring compound containing two N atoms and ketone in the same molecule. Lactam structure is an active nucleaus in pharmacological activity, especially in the class of nonsteroidal antiinflammatory agents used in the treatment of arthritis and other musculo skeletal and joint disorders. Pyrazolone derivatives, as lactam structure related compounds, are also widely used in preparing dyes and pigments. 4-aminoantipyrene and its derivatives have potential biological activities (Jain et al., 2003). Analgesic and antiinflammatory activities of the 4-aminoantipyrene complexes were extensively studied and reported (Filho et al., 1998; Sondhi et al., 1999). Apart from that, antimicrobial and anticancer activity of the 4-aminoantipyrine derivatives and their metal complexes caught the attention of many researchers during last decade (Mishra, 1999; Sondhi et al., 2001). As intra- and intermolecular hydrogen bonding interactions play a key role in bio-molecular interactions we are interested on the structural elucidation of potentially bioactive compounds and their hydrogen bonding interactions in different environments. Thus, we are concerned with the biomolecular hydrogen bonding interactions through their X-ray analyses of crystalline complexes involving drugs and vitamins with inorganic and organic acids (Athimoolam & Rajaram, 2005; Athimoolam & Natarajan, 2006a-c).

Intermolecular forces also play very essential role in the formation of supramolecular organic systems. The phenomenon of hydrogen bonding enlightens the area of molecular recognition, crystal-engineering research and organic synthons for supramolecular research (Desiraju, 1989). Carboxylic acids and amines are two commonly used functional groups in crystal engineering because they generally form robust architectures via O—H···O and N—H···O hydrogen-bonded interactions (Etter et al., 1990). 4-aminoantipyrene is one of the such important ligands since it has potential sites for hydrogen bonding interactions, viz., the amine N atom (as donor) and carbonyl O atom (as acceptor). Consideration of these above specifics and to study the supramolecular geometry through hydrogen bonding extensions, the present investigation was undertaken. 4-aminoantipyrene was treated with salicylic acid and the title compound is crystallized.

The asymmetric unit of (I) consists of one single charged protonated 4-aminoantipyrene cation and a deprotonated salicylate anion (Fig 1). Interatomic distances and angles are normal and in good agreement with the similar structures (Allen, 2002). The expected proton transfer from salicylic acid to 4-aminoantipyrene is established at N5 atom. The protonation on the N site of the cation is evidenced from the elongated C—N bond distance and the deprotonation on anion is confirmed from the COO- symmetric bond distances (Table 1). The phenyl ring of the cation is oriented with an angle of 67.0 (1)° to the five membered pyrazolone ring. Also, in the asymmeric unit, the phenyl ring of the cation is making a dihedral angle of 87.5 (1)° with the phenyl ring of the anion. The carboxylate plane of the salicylate anion is twisted from the plane of the aromatic ring with an angle of 13.7 (3)°. The twisting of carboxylate plane can be associated with the hydrogen bonding interactions of amino group of the cation. Due to the packing specificity of the crystal, one of the methyl atoms (C22) of the cation is slightly out of plane of the five-membered pyrzalone ring with the distance of 0.542 (3) Å.

The most elegant aspect of the present work is found not only in the molecular structure but also in the crystal packing via N—H···O and O—H···O hydrogen bonds. Fig. 2 shows the aggregation of the molecules around the inversion centres of the unit cell through ring motifs. As a characterestic H-bond, salicylate anion consists a self associated intramolecular S(6) motif through O—H···O hydrogen bond. The amino group of the cation is involved in two two-centered and one three-centered hydrogen bonds. The amino and carbonyl O atom of the cation is involving in N—H···O hydrogen bond which leads to a classical molecular dimerization through the ring R22(10) motif around the inversion center of the unit cell (Fig. 3). Other two H atoms of amino group are involved in N—H···O hydrogen bonds with the adjascent salicylate anions. This leads to another ring R42(8) motif formed through two cations and two anions (Fig. 4). This ring motif is further accompanied with another adajascent ring R12(4) motif through the bifuracted (two-centered) hydrogen bond. These three intermolecular ring motifs are intersected and extending along the a axis of the unit cell. This leads to hydrophilic region at the plane y=1/2 which are sanwitched between the hydrophobic regions at y=1/4 and 3/4.

Experimental

The title compound was crystallized from the aqueous mixtures of 4-aminoantipyrene with salicylic acid, in the stochiometric ratio of 1:1 at room temperature by the technique of slow evaporation.

Refinement

All the H atoms were positioned geometrically and refined using a riding model, with C—H = 0.93 Å (aromatic) & 0.96 Å (methyl), N—H = 0.86 Å and O—H=0.82 Å and Uiso(H) = 1.2–1.5 Ueq (parent atom).

Figures

Fig. 1.
The molecular structure of the title compound with atom numbering scheme and 50% probability displacement ellipsoids. H-bonds are shown as dashed lines.
Fig. 2.
Packing diagram of the title compound viewed down the a-axis. H-bonds are shown as dashed lines.
Fig. 3.
Inversion related ring R22(10) motif. Hydrogen atoms not involved in hydrogen bonds (dashed lines) are omitted for clarity.
Fig. 4.
Intermolecular ring R12(4) and R42(8) motifs and intramolecular S(6) motif. Hydrogen atoms not involved in hydrogen bonds (dashed lines) are omitted for clarity.

Crystal data

C11H14N3O+·C7H5O3F(000) = 720
Mr = 341.36Dx = 1.349 Mg m3Dm = 1.339 Mg m3Dm measured by flotation technique using a liquid-mixture of xylene and carbon tetrachloride
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 3884 reflections
a = 8.3182 (6) Åθ = 2.6–23.9°
b = 23.3006 (16) ŵ = 0.10 mm1
c = 8.8503 (6) ÅT = 293 K
β = 101.517 (1)°Needle, light orange
V = 1680.8 (2) Å30.24 × 0.13 × 0.12 mm
Z = 4

Data collection

Bruker SMART APEX CCD area-detector diffractometer2599 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.020
graphiteθmax = 25.0°, θmin = 1.8°
ω scansh = −9→9
16025 measured reflectionsk = −27→27
2959 independent reflectionsl = −10→10

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)] = 0.041Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.113H-atom parameters constrained
S = 1.05w = 1/[σ2(Fo2) + (0.0515P)2 + 0.4777P] where P = (Fo2 + 2Fc2)/3
2959 reflections(Δ/σ)max < 0.001
229 parametersΔρmax = 0.18 e Å3
0 restraintsΔρmin = −0.18 e Å3

Special details

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)

xyzUiso*/Ueq
C10.88415 (19)0.55024 (6)0.81347 (17)0.0448 (3)
C111.0648 (2)0.54675 (8)0.8259 (2)0.0584 (4)
H11A1.08980.51680.75970.088*
H11C1.11640.53850.93060.088*
H11B1.10480.58270.79550.088*
N20.81742 (15)0.57725 (6)0.92231 (15)0.0484 (3)
C220.8940 (2)0.62350 (8)1.0208 (2)0.0625 (5)
H22A1.00710.61431.06030.094*
H22B0.83830.62851.10500.094*
H22C0.88740.65840.96210.094*
N30.64810 (15)0.57811 (6)0.86977 (15)0.0496 (3)
C40.60726 (19)0.54839 (7)0.73428 (17)0.0479 (4)
O40.46461 (14)0.53935 (6)0.66452 (14)0.0662 (4)
C50.75999 (18)0.53088 (6)0.70220 (16)0.0442 (3)
N50.77414 (16)0.50034 (6)0.56334 (14)0.0508 (3)
H5A0.67440.49260.50910.076*
H5B0.82860.46770.58830.076*
H5C0.82810.52190.50710.076*
C310.54080 (18)0.60115 (7)0.96225 (17)0.0471 (4)
C320.4479 (2)0.64820 (8)0.9101 (2)0.0619 (5)
H320.45160.66400.81440.074*
C330.3485 (2)0.67208 (9)1.0009 (3)0.0743 (6)
H330.28470.70400.96610.089*
C340.3436 (2)0.64892 (10)1.1417 (2)0.0697 (6)
H340.27850.66571.20370.084*
C350.4341 (2)0.60110 (10)1.1917 (2)0.0680 (5)
H350.42850.58501.28670.082*
C360.5338 (2)0.57665 (8)1.10183 (19)0.0588 (4)
H360.59520.54411.13540.071*
C410.9974 (3)0.38422 (8)0.5503 (2)0.0628 (5)
C421.0840 (2)0.34016 (6)0.47447 (17)0.0493 (4)
C431.2516 (2)0.34179 (8)0.4878 (2)0.0653 (5)
H431.31230.37030.54720.078*
C441.3309 (3)0.30161 (12)0.4140 (3)0.0940 (8)
H441.44450.30220.42550.113*
C451.2386 (5)0.26065 (11)0.3230 (3)0.1051 (10)
H451.29070.23400.27080.126*
C461.0744 (4)0.25848 (9)0.3083 (3)0.0926 (8)
H461.01430.23090.24520.111*
C470.9954 (3)0.29676 (8)0.3861 (2)0.0652 (5)
O411.0717 (2)0.42857 (6)0.60326 (16)0.0872 (5)
O420.8508 (2)0.37591 (8)0.5565 (2)0.0980 (5)
O430.8319 (2)0.29178 (8)0.3741 (2)0.1032 (6)
H43A0.80040.31560.42990.155*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
C10.0488 (8)0.0453 (8)0.0415 (8)0.0025 (6)0.0118 (6)−0.0012 (6)
C110.0492 (9)0.0706 (11)0.0555 (10)0.0023 (8)0.0105 (8)−0.0107 (8)
N20.0448 (7)0.0555 (8)0.0444 (7)−0.0020 (6)0.0080 (5)−0.0119 (6)
C220.0581 (10)0.0703 (11)0.0590 (10)−0.0100 (8)0.0115 (8)−0.0230 (9)
N30.0436 (7)0.0609 (8)0.0443 (7)0.0016 (6)0.0088 (5)−0.0139 (6)
C40.0489 (9)0.0531 (9)0.0406 (8)0.0024 (7)0.0066 (7)−0.0087 (7)
O40.0479 (7)0.0914 (9)0.0559 (7)0.0057 (6)0.0025 (5)−0.0288 (6)
C50.0494 (9)0.0454 (8)0.0383 (7)0.0036 (6)0.0098 (6)−0.0049 (6)
N50.0518 (7)0.0569 (8)0.0437 (7)0.0071 (6)0.0095 (6)−0.0109 (6)
C310.0440 (8)0.0532 (9)0.0450 (8)−0.0031 (7)0.0109 (6)−0.0134 (7)
C320.0641 (11)0.0649 (11)0.0595 (10)0.0077 (9)0.0191 (8)−0.0014 (8)
C330.0668 (12)0.0720 (12)0.0878 (15)0.0153 (10)0.0244 (11)−0.0116 (11)
C340.0518 (10)0.0900 (14)0.0725 (12)−0.0073 (10)0.0244 (9)−0.0326 (11)
C350.0634 (11)0.0938 (15)0.0514 (10)−0.0145 (11)0.0225 (9)−0.0117 (10)
C360.0611 (10)0.0660 (11)0.0508 (9)−0.0003 (8)0.0149 (8)−0.0047 (8)
C410.0865 (14)0.0587 (11)0.0490 (9)0.0174 (10)0.0277 (9)0.0136 (8)
C420.0662 (10)0.0418 (8)0.0419 (8)0.0044 (7)0.0153 (7)0.0065 (6)
C430.0689 (12)0.0627 (11)0.0668 (11)0.0065 (9)0.0199 (9)0.0089 (9)
C440.0935 (17)0.0945 (17)0.1083 (19)0.0351 (14)0.0544 (15)0.0320 (15)
C450.181 (3)0.0629 (14)0.0896 (18)0.0378 (18)0.071 (2)0.0077 (13)
C460.165 (3)0.0485 (11)0.0661 (13)0.0005 (14)0.0285 (15)−0.0055 (9)
C470.0919 (14)0.0491 (10)0.0537 (10)−0.0046 (9)0.0125 (9)0.0113 (8)
O410.1512 (15)0.0554 (8)0.0651 (9)0.0028 (8)0.0456 (9)−0.0106 (7)
O420.0848 (11)0.1136 (13)0.1090 (13)0.0311 (9)0.0514 (10)0.0239 (10)
O430.0926 (12)0.0962 (13)0.1114 (14)−0.0326 (9)−0.0020 (10)0.0149 (10)

Geometric parameters (Å, °)

C1—C51.354 (2)C33—C341.366 (3)
C1—N21.3585 (19)C33—H330.9300
C1—C111.487 (2)C34—C351.368 (3)
C11—H11A0.9600C34—H340.9300
C11—H11C0.9600C35—C361.381 (3)
C11—H11B0.9600C35—H350.9300
N2—N31.3924 (18)C36—H360.9300
N2—C221.451 (2)C41—O421.246 (2)
C22—H22A0.9600C41—O411.247 (2)
C22—H22B0.9600C41—C421.489 (2)
C22—H22C0.9600C42—C431.376 (3)
N3—C41.3675 (19)C42—C471.395 (2)
N3—C311.4306 (19)C43—C441.382 (3)
C4—O41.2414 (19)C43—H430.9300
C4—C51.416 (2)C44—C451.379 (4)
C5—N51.4450 (18)C44—H440.9300
N5—H5A0.8900C45—C461.347 (4)
N5—H5B0.8900C45—H450.9300
N5—H5C0.8900C46—C471.372 (3)
C31—C321.367 (2)C46—H460.9300
C31—C361.373 (2)C47—O431.348 (3)
C32—C331.380 (3)O43—H43A0.8200
C32—H320.9300
C5—C1—N2108.04 (13)C31—C32—H32120.3
C5—C1—C11130.42 (14)C33—C32—H32120.3
N2—C1—C11121.52 (13)C34—C33—C32120.15 (19)
C1—C11—H11A109.5C34—C33—H33119.9
C1—C11—H11C109.5C32—C33—H33119.9
H11A—C11—H11C109.5C33—C34—C35120.15 (17)
C1—C11—H11B109.5C33—C34—H34119.9
H11A—C11—H11B109.5C35—C34—H34119.9
H11C—C11—H11B109.5C34—C35—C36120.29 (18)
C1—N2—N3107.41 (12)C34—C35—H35119.9
C1—N2—C22125.26 (14)C36—C35—H35119.9
N3—N2—C22118.91 (13)C31—C36—C35119.02 (18)
N2—C22—H22A109.5C31—C36—H36120.5
N2—C22—H22B109.5C35—C36—H36120.5
H22A—C22—H22B109.5O42—C41—O41121.88 (19)
N2—C22—H22C109.5O42—C41—C42118.59 (19)
H22A—C22—H22C109.5O41—C41—C42119.52 (19)
H22B—C22—H22C109.5C43—C42—C47118.73 (17)
C4—N3—N2110.07 (12)C43—C42—C41121.05 (17)
C4—N3—C31128.14 (13)C47—C42—C41120.21 (18)
N2—N3—C31121.29 (12)C42—C43—C44120.8 (2)
O4—C4—N3124.58 (14)C42—C43—H43119.6
O4—C4—C5131.15 (14)C44—C43—H43119.6
N3—C4—C5104.24 (13)C45—C44—C43118.8 (2)
C1—C5—C4110.04 (13)C45—C44—H44120.6
C1—C5—N5127.06 (14)C43—C44—H44120.6
C4—C5—N5122.76 (13)C46—C45—C44121.2 (2)
C5—N5—H5A109.5C46—C45—H45119.4
C5—N5—H5B109.5C44—C45—H45119.4
H5A—N5—H5B109.5C45—C46—C47120.4 (2)
C5—N5—H5C109.5C45—C46—H46119.8
H5A—N5—H5C109.5C47—C46—H46119.8
H5B—N5—H5C109.5O43—C47—C46118.8 (2)
C32—C31—C36120.94 (15)O43—C47—C42121.22 (18)
C32—C31—N3118.89 (15)C46—C47—C42120.0 (2)
C36—C31—N3120.16 (15)C47—O43—H43A109.5
C31—C32—C33119.41 (18)
C5—C1—N2—N3−4.57 (17)C36—C31—C32—C331.5 (3)
C11—C1—N2—N3174.07 (14)N3—C31—C32—C33−177.62 (17)
C5—C1—N2—C22−151.94 (16)C31—C32—C33—C340.2 (3)
C11—C1—N2—C2226.7 (2)C32—C33—C34—C35−1.6 (3)
C1—N2—N3—C44.24 (17)C33—C34—C35—C361.4 (3)
C22—N2—N3—C4154.04 (15)C32—C31—C36—C35−1.7 (3)
C1—N2—N3—C31176.75 (14)N3—C31—C36—C35177.43 (15)
C22—N2—N3—C31−33.5 (2)C34—C35—C36—C310.2 (3)
N2—N3—C4—O4176.11 (16)O42—C41—C42—C43−168.40 (17)
C31—N3—C4—O44.2 (3)O41—C41—C42—C4312.8 (2)
N2—N3—C4—C5−2.15 (17)O42—C41—C42—C4712.6 (2)
C31—N3—C4—C5−174.00 (15)O41—C41—C42—C47−166.22 (16)
N2—C1—C5—C43.34 (18)C47—C42—C43—C440.6 (3)
C11—C1—C5—C4−175.14 (16)C41—C42—C43—C44−178.37 (17)
N2—C1—C5—N5179.12 (14)C42—C43—C44—C451.8 (3)
C11—C1—C5—N50.6 (3)C43—C44—C45—C46−1.6 (4)
O4—C4—C5—C1−178.80 (18)C44—C45—C46—C47−1.0 (4)
N3—C4—C5—C1−0.71 (18)C45—C46—C47—O43−177.1 (2)
O4—C4—C5—N55.2 (3)C45—C46—C47—C423.4 (3)
N3—C4—C5—N5−176.71 (14)C43—C42—C47—O43177.36 (17)
C4—N3—C31—C32−72.0 (2)C41—C42—C47—O43−3.6 (2)
N2—N3—C31—C32116.97 (17)C43—C42—C47—C46−3.2 (3)
C4—N3—C31—C36108.9 (2)C41—C42—C47—C46175.77 (16)
N2—N3—C31—C36−62.1 (2)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N5—H5A···O4i0.891.882.696 (2)151
N5—H5B···O410.892.202.949 (2)142
N5—H5B···O420.892.172.972 (2)150
N5—H5C···O41ii0.891.822.705 (2)175
O43—H43A···O420.821.792.524 (3)148

Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x+2, −y+1, −z+1.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BT5124).

References

  • Allen, F. H. (2002). Acta Cryst. B58, 380–388. [PubMed]
  • Athimoolam, S. & Natarajan, S. (2006a). Acta Cryst. C62, o612–o617. [PubMed]
  • Athimoolam, S. & Natarajan, S. (2006b). Acta Cryst. E62, o4027–o4029.
  • Athimoolam, S. & Natarajan, S. (2006c). Acta Cryst. E62, o4219–o4221.
  • Athimoolam, S. & Rajaram, R. K. (2005). Acta Cryst. E61, o2764–o2767.
  • Bruker (2001). SAINT and SMART. Bruker AXS Inc., Madison, Wisconsin, USA.
  • Desiraju, G. R. (1989). Crystal Engineering: The Design of Organic Solids. Elsevier: Amsterdam.
  • Etter, M. C., MacDonald, J. C. & Bernstein, J. (1990). Acta Cryst. B46, 256–262. [PubMed]
  • Filho, V. C., Correa, R., Vaz, Z., Calixto, J. B., Nunes, R. J., Pinheiro, T. R., Andrcopulo, A. D. & Yunes, R. A. (1998). Il Farmaco, 53, 55–58.
  • Jain, S. C., Sinha, S., Bhagat, S., Errington, W. & Olsen, C. E. (2003). Synth. Commun. 33, 563–577.
  • Macrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., Towler, M. & van de Streek, J. (2006). J. Appl. Cryst. 39, 453–457.
  • Mishra, A. P. (1999). J. Indian Chem. Soc. 76, 35–37.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Sondhi, S. M., Sharma, V. K., Verma, R. P., Singhal, N., Shukla, R., Raghubir, R. & Dubey, M. P. (1999). Synthesis, pp. 878–884.
  • Sondhi, S. M., Singhal, N., Verma, R. P., Arora, S. K. & Dastidar, S. G. (2001). Indian J. Chem. Sect. B, 40, 113–119.
  • 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