organic compounds
A second polymorph of (Z)-3-amino-4-(2-phenylhydrazinylidene)-1H-pyrazol-5(4H)-one
aChemistry Department, Faculty of Science, Ain Shams University, Abbassia 11566, Cairo, Egypt, and bInstitut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Postfach 3329, 38023 Braunschweig, Germany
*Correspondence e-mail: p.jones@tu-bs.de
The molecule of the title compound, C9H9N5O, is approximately planar (the r.m.s. deviation of all non-H atoms is 0.08 Å). The amine substituent is pyramidal at the N atom. An intramolecular N—Hhydrazine⋯O=C hydrogen bond is present. In the crystal, molecules are connected via N—H⋯N and N—H⋯O hydrogen bonds, forming infinite layers parallel to (010). This polymorph is triclinic, P-1, whereas the previously reported form was monoclinic, P21/c [Elgemeie et al. (2013). Acta Cryst. E69, o187], with stepped layers and a significantly lower density.
CCDC reference: 980594
Related literature
Synthetic purine (Hamad & Derbala, 2001) and pyrazole (Elgazwy, 2003; Madkour & Elgazwy, 2007) analogues find numerous applications in clinical medicine and medical research. For the synthesis, chemistry, medicinal chemistry and biological activity of related compounds, see: Elgazwy et al. (2012a,b, 2013); Arnost et al. (2010). For the monoclinic polymorph of the title compound, see: Elgemeie et al. (2013, 2014). For a description of the Cambridge Structural Database, see: Allen (2002).
Experimental
Crystal data
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Data collection: CrysAlis PRO (Agilent, 2010); cell CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97.
Supporting information
CCDC reference: 980594
10.1107/S1600536814000427/zq2216sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536814000427/zq2216Isup2.hkl
Supporting information file. DOI: 10.1107/S1600536814000427/zq2216Isup3.cml
The title compound was obtained according to the following general procedure (Arnost et al., 2010): 3-amino-1H-pyrazol-5(4H)-one was prepared by refluxing an ethanolic solution of sodium cyanoacetate and sodium ethoxide containing a few drops of hydrazine hydrate for 1 h. After cooling, the precipitate was filtered off and recrystallized from ethanol. A solution of freshly prepared phenyldiazonium chloride (2.66 mmol) was added to the pyrazolone (1 equiv in 50% aqueous EtOH, 3 ml/mmol)and potassium acetate (6 equiv) and the mixture stirred at 0 °C for a further 30 min. The precipitate was filtered, washed with water and dried to give (Z)-3-amino-4-(2-phenylhydrazono)-1H-pyrazol-5(4H)-one (I). Recrystallization from ethanol afforded reddish-brown crystals in 87% yield; m.p. 119–120 °C (dec). Red single crystals of I were obtained by slow diffusion of water into a ethanol solution. Most crystals were swallowtail twins; single crystalline fragments could be separated using a razor blade. IR (KBr, ν (cm-1): 3449, 3350, 3330, 3300 (NH2, 2NH), 1702, 1668 (C═O), 1627 (C═N), 1475 (N═N); 1H NMR (300 MHz, DMSO-d6): δ 6.85 (s, br, 2H, NH2), 7.41–7.92 (m, 5H, Ph), 10.71 (s, br, 1H, NH, pyrazole), 14.18 (br, 1H, NH, hydrazone); 13C-NMR (DMSO-d6): δ 175.9 (C═O), 162.2 (C-5), 154.3 (C-3), 154.2 (C-4), 143.2 (C-i), 129.7 (C-m), 120.0 (C-p), 117.9 (C-o). Anal. Calcd for for C9H9N5O (203); C, 53.20; H, 4.46; N, 34.47. Found: C, 53.27; H, 4.51; N, 34.12%.
The NH H atoms were refined freely. Other H were placed in calculated positions and refined using a riding model with C—Harom 0.95 Å; the hydrogen U values were fixed at 1.2 × U(eq) of the parent atom for these H.
Synthetic purine (Hamad & Derbala, 2001) and pyrazole (Elgazwy, 2003; Madkour & Elgazwy, 2007) analogues find numerous applications in clinical medicine and medical research. As part of our work directed towards the synthesis of pyrazolones (Elgazwy et al., 2012a, 2012b), we have recently reported various successful approaches to the syntheses of pyrazolone analogues that are interesting for biochemical reactions. The title compound (Z)-3-amino-4-(2-phenylhydrazono)-1H-pyrazol-5(4H)-one (I) was prepared in the course of these investigations.
By chance, compound I was also prepared and structurally investigated during a collaboration with a different group (Elgemeie et al., 2013, 2014; regrettably, the stereochemistry was erroneously described as E). The current structure proved to be a different polymorph of I, being triclinic (space group P1; henceforth It) rather than monoclinic (space group P21/c; henceforth Im).
The molecule of It is shown in Fig. 1. Molecular dimensions, such as the bond lengths C4═N4 1.3070 (10) and N4—N5 1.3128 (9) Å, may be regarded as normal. A search of the Cambridge Database (Allen, 2002; Version 1.15) for the same five-membered ring with C═O and C═N—N substituents gave average bond lengths of 1.309 (8) and 1.318 (10) Å respectively for these bonds (35 hits, 39 fragments excluding one obvious outlier). The nitrogen N3 of the amine substituent is pyramidal, lying 0.224 (8) Å out of the plane of its substituents. The entire molecule is planar to within an r.m.s. deviation of 0.08 Å for the non-H atoms, with no torsion angle deviating by more than 6.5 ° from 0/180 °; this is in part attributable to the intramolecular hydrogen bond N5—H05···O1. A more detailed analysis shows two planar units (i) C11–16 with substituent N5 and (ii) the five-membered ring, both with r.m.s.d. 0.004 Å, that subtend an interplanar angle of 8.51 (4) °. The substituents O1, N4 and N3 all lie slightly but significantly out of the plane of the five-membered ring, by 0.057 (1), 0.095 (1) and 0.069 (1) Å respectively, all to the same side. A comparison with Im shows that the molecules are closely similar except for a slight difference in the orientation of the phenyl ring; a least-squares fit excluding the non-ipso phenyl carbon atoms gives an r.m.s. deviation of 0.04 Å. However, there are some significant differences such as the N1—C5 bond length, which is 1.3387 (13) Å in Im but 1.3489 (10) Å in It.
The molecules of It are connected by hydrogen bonds (Table 1) to form infinite layers (one per b translation) parallel to the ac plane (Fig. 2). There are two three-centre interactions (N5—H05···O1 intra- and intermolecular, N1—H01···N1/N2) and two two-centre interactions involving the NH2 H atoms (with N2 and O1 as acceptors). In Im, one of the N3 H atoms forms a three-centre system with N1 and N2, the N5—H05···O1 interaction is purely two-centre, N1—H01 and N3—H03A are two-centre donors to O1. The packing of Im is a stepped layer structure that intuitively seems to display a less efficient packing than that of It; consistent with this are the crystallographic densities of 1.464 and 1.491 g cm-3, respectively, but we have carried out no further calculations or experiments to test this hypothesis.
Synthetic purine (Hamad & Derbala, 2001) and pyrazole (Elgazwy, 2003; Madkour & Elgazwy, 2007) analogues find numerous applications in clinical medicine and medical research. For the synthesis, chemistry, medicinal chemistry and biological activity of related compounds, see: Elgazwy et al. (2012a,b, 2013); Arnost et al. (2010). For the monoclinic polymorph of the title compound, see: Elgemeie et al. (2013, 2014). For a description of the Cambridge Structural Database, see: Allen (2002).
Data collection: CrysAlis PRO (Agilent, 2010); cell
CrysAlis PRO (Agilent, 2010); data reduction: CrysAlis PRO (Agilent, 2010); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).Fig. 1. The molecule of the title compound in the crystal; ellipsoids represent 50% probability levels. | |
Fig. 2. Packing diagram of the title compound viewed perpendicular to the ac plane. Phenyl rings are reduced to the ipso carbons for clarity. Intramolecular hydrogen bonds are drawn as thin and intermolecular hydrogen bonds as thick dashed lines; the latter are numbered according to their order in the relevant Table. H bonds #4 are omitted because they represent the weak components of asymmetric three-centre interactions. |
C9H9N5O | Z = 2 |
Mr = 203.21 | F(000) = 212 |
Triclinic, P1 | Dx = 1.491 Mg m−3 |
Hall symbol: -P 1 | Melting point = 120–119 K |
a = 6.4433 (4) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 7.4563 (5) Å | Cell parameters from 18469 reflections |
c = 10.1989 (6) Å | θ = 2.9–31.4° |
α = 80.005 (5)° | µ = 0.11 mm−1 |
β = 81.271 (5)° | T = 100 K |
γ = 70.512 (5)° | Tablet, brown-orange dichroic |
V = 452.57 (5) Å3 | 0.40 × 0.35 × 0.15 mm |
Oxford Diffraction Xcalibur Eos diffractometer | 2848 independent reflections |
Radiation source: Enhance (Mo) X-ray Source | 2649 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.022 |
Detector resolution: 16.1419 pixels mm-1 | θmax = 31.5°, θmin = 2.9° |
ω–scan | h = −9→9 |
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010) | k = −10→10 |
Tmin = 0.948, Tmax = 1.000 | l = −14→14 |
31042 measured reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.037 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.107 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | w = 1/[σ2(Fo2) + (0.0618P)2 + 0.1329P] where P = (Fo2 + 2Fc2)/3 |
2848 reflections | (Δ/σ)max < 0.001 |
152 parameters | Δρmax = 0.54 e Å−3 |
0 restraints | Δρmin = −0.19 e Å−3 |
C9H9N5O | γ = 70.512 (5)° |
Mr = 203.21 | V = 452.57 (5) Å3 |
Triclinic, P1 | Z = 2 |
a = 6.4433 (4) Å | Mo Kα radiation |
b = 7.4563 (5) Å | µ = 0.11 mm−1 |
c = 10.1989 (6) Å | T = 100 K |
α = 80.005 (5)° | 0.40 × 0.35 × 0.15 mm |
β = 81.271 (5)° |
Oxford Diffraction Xcalibur Eos diffractometer | 2848 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010) | 2649 reflections with I > 2σ(I) |
Tmin = 0.948, Tmax = 1.000 | Rint = 0.022 |
31042 measured reflections |
R[F2 > 2σ(F2)] = 0.037 | 0 restraints |
wR(F2) = 0.107 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | Δρmax = 0.54 e Å−3 |
2848 reflections | Δρmin = −0.19 e Å−3 |
152 parameters |
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. Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane) 1.7900 (0.0023) x + 6.5551 (0.0012) y - 3.2198 (0.0028) z = 1.0389 (0.0022) * -0.0005 (0.0005) N5 * 0.0026 (0.0007) C11 * -0.0059 (0.0007) C12 * 0.0039 (0.0006) C13 * 0.0020 (0.0007) C14 * -0.0064 (0.0006) C15 * 0.0043 (0.0007) C16 Rms deviation of fitted atoms = 0.0041 1.7459 (0.0026) x + 6.9955 (0.0012) y - 1.8138 (0.0040) z = 1.9727 (0.0038) Angle to previous plane (with approximate e.s.d.) = 8.51 (0.04) * 0.0048 (0.0005) C4 * -0.0057 (0.0005) C5 * 0.0045 (0.0005) N1 * -0.0011 (0.0005) N2 * -0.0025 (0.0005) C3 - 0.0571 (0.0012) O1 - 0.0953 (0.0013) N4 - 0.0691 (0.0013) N3 Rms deviation of fitted atoms = 0.0041 0.9251 (0.0393) x + 7.1132 (0.0235) y - 0.8552 (0.1393) z = 2.4580 (0.1235) Angle to previous plane (with approximate e.s.d.) = 10.20 (0.77) * 0.0000 (0.0001) C3 * 0.0000 (0.0001) H031 * 0.0000 (0.0000) H032 - 0.2236 (0.0081) N3 Rms deviation of fitted atoms = 0.0000 |
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. |
x | y | z | Uiso*/Ueq | ||
N1 | 0.07044 (12) | 0.48559 (11) | 0.85055 (7) | 0.01658 (16) | |
H01 | −0.069 (2) | 0.523 (2) | 0.8985 (14) | 0.026 (3)* | |
N2 | 0.26071 (11) | 0.45453 (11) | 0.91700 (7) | 0.01619 (15) | |
C3 | 0.43103 (13) | 0.38930 (11) | 0.83013 (8) | 0.01377 (16) | |
C4 | 0.36028 (13) | 0.37553 (11) | 0.70490 (8) | 0.01289 (15) | |
C5 | 0.11746 (13) | 0.43979 (11) | 0.72476 (8) | 0.01381 (16) | |
C11 | 0.53773 (13) | 0.20424 (11) | 0.39128 (8) | 0.01417 (16) | |
C12 | 0.43303 (15) | 0.18095 (12) | 0.28826 (9) | 0.01816 (17) | |
H12 | 0.2761 | 0.2239 | 0.2922 | 0.022* | |
C13 | 0.56037 (17) | 0.09431 (13) | 0.17965 (9) | 0.02246 (19) | |
H13 | 0.4900 | 0.0798 | 0.1085 | 0.027* | |
C14 | 0.78986 (17) | 0.02890 (13) | 0.17463 (9) | 0.0239 (2) | |
H14 | 0.8762 | −0.0305 | 0.1004 | 0.029* | |
C15 | 0.89267 (16) | 0.05055 (13) | 0.27848 (10) | 0.02299 (19) | |
H15 | 1.0495 | 0.0042 | 0.2754 | 0.028* | |
C16 | 0.76831 (14) | 0.13954 (12) | 0.38721 (9) | 0.01822 (17) | |
H16 | 0.8392 | 0.1559 | 0.4574 | 0.022* | |
N3 | 0.64559 (12) | 0.33318 (11) | 0.85693 (7) | 0.01741 (16) | |
H031 | 0.671 (3) | 0.370 (2) | 0.9308 (16) | 0.035 (4)* | |
H032 | 0.743 (2) | 0.343 (2) | 0.7861 (15) | 0.032 (4)* | |
N4 | 0.49280 (11) | 0.30196 (10) | 0.60388 (7) | 0.01314 (14) | |
N5 | 0.40314 (11) | 0.29333 (10) | 0.49879 (7) | 0.01411 (15) | |
H05 | 0.253 (2) | 0.345 (2) | 0.4940 (14) | 0.027 (3)* | |
O1 | −0.01526 (10) | 0.44520 (9) | 0.64628 (6) | 0.01777 (14) |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0113 (3) | 0.0266 (4) | 0.0117 (3) | −0.0051 (3) | 0.0009 (2) | −0.0060 (3) |
N2 | 0.0118 (3) | 0.0242 (3) | 0.0130 (3) | −0.0053 (3) | −0.0002 (2) | −0.0054 (3) |
C3 | 0.0129 (3) | 0.0170 (3) | 0.0117 (3) | −0.0054 (3) | 0.0003 (3) | −0.0029 (3) |
C4 | 0.0116 (3) | 0.0157 (3) | 0.0113 (3) | −0.0046 (3) | 0.0007 (3) | −0.0024 (3) |
C5 | 0.0121 (3) | 0.0168 (3) | 0.0117 (3) | −0.0042 (3) | 0.0011 (3) | −0.0024 (3) |
C11 | 0.0160 (3) | 0.0135 (3) | 0.0116 (3) | −0.0037 (3) | 0.0017 (3) | −0.0027 (3) |
C12 | 0.0208 (4) | 0.0175 (4) | 0.0155 (4) | −0.0041 (3) | −0.0021 (3) | −0.0041 (3) |
C13 | 0.0330 (5) | 0.0195 (4) | 0.0143 (4) | −0.0069 (3) | −0.0007 (3) | −0.0051 (3) |
C14 | 0.0314 (5) | 0.0192 (4) | 0.0179 (4) | −0.0064 (3) | 0.0084 (3) | −0.0069 (3) |
C15 | 0.0204 (4) | 0.0210 (4) | 0.0243 (4) | −0.0045 (3) | 0.0078 (3) | −0.0073 (3) |
C16 | 0.0157 (4) | 0.0194 (4) | 0.0181 (4) | −0.0039 (3) | 0.0021 (3) | −0.0050 (3) |
N3 | 0.0124 (3) | 0.0268 (4) | 0.0137 (3) | −0.0062 (3) | −0.0001 (2) | −0.0057 (3) |
N4 | 0.0139 (3) | 0.0142 (3) | 0.0113 (3) | −0.0050 (2) | 0.0003 (2) | −0.0020 (2) |
N5 | 0.0124 (3) | 0.0177 (3) | 0.0116 (3) | −0.0034 (2) | 0.0005 (2) | −0.0044 (2) |
O1 | 0.0138 (3) | 0.0252 (3) | 0.0137 (3) | −0.0046 (2) | −0.0017 (2) | −0.0037 (2) |
N1—C5 | 1.3489 (10) | C12—H12 | 0.9500 |
N1—N2 | 1.4227 (10) | C13—C14 | 1.3898 (15) |
N1—H01 | 0.931 (14) | C13—H13 | 0.9500 |
N2—C3 | 1.3130 (10) | C14—C15 | 1.3894 (14) |
C3—N3 | 1.3602 (10) | C14—H14 | 0.9500 |
C3—C4 | 1.4502 (11) | C15—C16 | 1.3939 (12) |
C4—N4 | 1.3070 (10) | C15—H15 | 0.9500 |
C4—C5 | 1.4682 (11) | C16—H16 | 0.9500 |
C5—O1 | 1.2438 (10) | N3—H031 | 0.899 (16) |
C11—C12 | 1.3949 (11) | N3—H032 | 0.893 (15) |
C11—C16 | 1.3970 (12) | N4—N5 | 1.3128 (9) |
C11—N5 | 1.4055 (10) | N5—H05 | 0.920 (14) |
C12—C13 | 1.3916 (12) | ||
C5—N1—N2 | 113.92 (7) | C14—C13—C12 | 120.35 (9) |
C5—N1—H01 | 127.2 (9) | C14—C13—H13 | 119.8 |
N2—N1—H01 | 118.6 (9) | C12—C13—H13 | 119.8 |
C3—N2—N1 | 105.54 (7) | C15—C14—C13 | 119.81 (8) |
N2—C3—N3 | 124.13 (7) | C15—C14—H14 | 120.1 |
N2—C3—C4 | 111.24 (7) | C13—C14—H14 | 120.1 |
N3—C3—C4 | 124.56 (7) | C14—C15—C16 | 120.74 (9) |
N4—C4—C3 | 124.84 (7) | C14—C15—H15 | 119.6 |
N4—C4—C5 | 129.43 (7) | C16—C15—H15 | 119.6 |
C3—C4—C5 | 105.40 (7) | C15—C16—C11 | 118.91 (8) |
O1—C5—N1 | 127.60 (8) | C15—C16—H16 | 120.5 |
O1—C5—C4 | 128.47 (7) | C11—C16—H16 | 120.5 |
N1—C5—C4 | 103.89 (7) | C3—N3—H031 | 116.3 (10) |
C12—C11—C16 | 120.73 (8) | C3—N3—H032 | 115.2 (9) |
C12—C11—N5 | 117.65 (7) | H031—N3—H032 | 114.2 (14) |
C16—C11—N5 | 121.62 (8) | C4—N4—N5 | 117.74 (7) |
C13—C12—C11 | 119.44 (8) | N4—N5—C11 | 119.81 (7) |
C13—C12—H12 | 120.3 | N4—N5—H05 | 121.2 (9) |
C11—C12—H12 | 120.3 | C11—N5—H05 | 119.0 (9) |
C5—N1—N2—C3 | 0.58 (10) | C16—C11—C12—C13 | −0.78 (13) |
N1—N2—C3—N3 | −176.87 (8) | N5—C11—C12—C13 | 179.67 (7) |
N1—N2—C3—C4 | 0.11 (9) | C11—C12—C13—C14 | 0.95 (13) |
N2—C3—C4—N4 | −174.62 (8) | C12—C13—C14—C15 | −0.15 (14) |
N3—C3—C4—N4 | 2.34 (13) | C13—C14—C15—C16 | −0.83 (14) |
N2—C3—C4—C5 | −0.68 (9) | C14—C15—C16—C11 | 0.99 (14) |
N3—C3—C4—C5 | 176.29 (8) | C12—C11—C16—C15 | −0.18 (13) |
N2—N1—C5—O1 | 176.90 (8) | N5—C11—C16—C15 | 179.36 (8) |
N2—N1—C5—C4 | −0.97 (9) | C3—C4—N4—N5 | 177.60 (7) |
N4—C4—C5—O1 | −3.32 (15) | C5—C4—N4—N5 | 5.17 (13) |
C3—C4—C5—O1 | −176.89 (8) | C4—N4—N5—C11 | −175.90 (7) |
N4—C4—C5—N1 | 174.52 (8) | C12—C11—N5—N4 | 173.50 (7) |
C3—C4—C5—N1 | 0.96 (8) | C16—C11—N5—N4 | −6.05 (12) |
D—H···A | D—H | H···A | D···A | D—H···A |
N5—H05···O1 | 0.920 (14) | 2.164 (14) | 2.8524 (9) | 130.9 (11) |
N5—H05···O1i | 0.920 (14) | 2.266 (14) | 3.0176 (10) | 138.6 (12) |
N1—H01···N2ii | 0.931 (14) | 2.089 (14) | 2.9272 (10) | 149.0 (12) |
N1—H01···N1ii | 0.931 (14) | 2.547 (14) | 3.0692 (14) | 115.8 (10) |
N3—H031···N2iii | 0.899 (16) | 2.369 (16) | 3.2424 (10) | 163.9 (13) |
N3—H032···O1iv | 0.893 (15) | 2.185 (15) | 3.0428 (10) | 161.0 (13) |
Symmetry codes: (i) −x, −y+1, −z+1; (ii) −x, −y+1, −z+2; (iii) −x+1, −y+1, −z+2; (iv) x+1, y, z. |
D—H···A | D—H | H···A | D···A | D—H···A |
N5—H05···O1 | 0.920 (14) | 2.164 (14) | 2.8524 (9) | 130.9 (11) |
N5—H05···O1i | 0.920 (14) | 2.266 (14) | 3.0176 (10) | 138.6 (12) |
N1—H01···N2ii | 0.931 (14) | 2.089 (14) | 2.9272 (10) | 149.0 (12) |
N1—H01···N1ii | 0.931 (14) | 2.547 (14) | 3.0692 (14) | 115.8 (10) |
N3—H031···N2iii | 0.899 (16) | 2.369 (16) | 3.2424 (10) | 163.9 (13) |
N3—H032···O1iv | 0.893 (15) | 2.185 (15) | 3.0428 (10) | 161.0 (13) |
Symmetry codes: (i) −x, −y+1, −z+1; (ii) −x, −y+1, −z+2; (iii) −x+1, −y+1, −z+2; (iv) x+1, y, z. |
Acknowledgements
The authors acknowledge the financial support of the Ain Shams University, established and supported under the Egyptian Government Cooperative Research Centers Program.
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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.
Synthetic purine (Hamad & Derbala, 2001) and pyrazole (Elgazwy, 2003; Madkour & Elgazwy, 2007) analogues find numerous applications in clinical medicine and medical research. As part of our work directed towards the synthesis of pyrazolones (Elgazwy et al., 2012a, 2012b), we have recently reported various successful approaches to the syntheses of pyrazolone analogues that are interesting for biochemical reactions. The title compound (Z)-3-amino-4-(2-phenylhydrazono)-1H-pyrazol-5(4H)-one (I) was prepared in the course of these investigations.
By chance, compound I was also prepared and structurally investigated during a collaboration with a different group (Elgemeie et al., 2013, 2014; regrettably, the stereochemistry was erroneously described as E). The current structure proved to be a different polymorph of I, being triclinic (space group P1; henceforth It) rather than monoclinic (space group P21/c; henceforth Im).
The molecule of It is shown in Fig. 1. Molecular dimensions, such as the bond lengths C4═N4 1.3070 (10) and N4—N5 1.3128 (9) Å, may be regarded as normal. A search of the Cambridge Database (Allen, 2002; Version 1.15) for the same five-membered ring with C═O and C═N—N substituents gave average bond lengths of 1.309 (8) and 1.318 (10) Å respectively for these bonds (35 hits, 39 fragments excluding one obvious outlier). The nitrogen N3 of the amine substituent is pyramidal, lying 0.224 (8) Å out of the plane of its substituents. The entire molecule is planar to within an r.m.s. deviation of 0.08 Å for the non-H atoms, with no torsion angle deviating by more than 6.5 ° from 0/180 °; this is in part attributable to the intramolecular hydrogen bond N5—H05···O1. A more detailed analysis shows two planar units (i) C11–16 with substituent N5 and (ii) the five-membered ring, both with r.m.s.d. 0.004 Å, that subtend an interplanar angle of 8.51 (4) °. The substituents O1, N4 and N3 all lie slightly but significantly out of the plane of the five-membered ring, by 0.057 (1), 0.095 (1) and 0.069 (1) Å respectively, all to the same side. A comparison with Im shows that the molecules are closely similar except for a slight difference in the orientation of the phenyl ring; a least-squares fit excluding the non-ipso phenyl carbon atoms gives an r.m.s. deviation of 0.04 Å. However, there are some significant differences such as the N1—C5 bond length, which is 1.3387 (13) Å in Im but 1.3489 (10) Å in It.
The molecules of It are connected by hydrogen bonds (Table 1) to form infinite layers (one per b translation) parallel to the ac plane (Fig. 2). There are two three-centre interactions (N5—H05···O1 intra- and intermolecular, N1—H01···N1/N2) and two two-centre interactions involving the NH2 H atoms (with N2 and O1 as acceptors). In Im, one of the N3 H atoms forms a three-centre system with N1 and N2, the N5—H05···O1 interaction is purely two-centre, N1—H01 and N3—H03A are two-centre donors to O1. The packing of Im is a stepped layer structure that intuitively seems to display a less efficient packing than that of It; consistent with this are the crystallographic densities of 1.464 and 1.491 g cm-3, respectively, but we have carried out no further calculations or experiments to test this hypothesis.