A second polymorph of (Z)-3-amino-4-(2-phenyl­hydrazinyl­idene)-1H-pyrazol-5(4H)-one

Abdel-Sattar S Hamad Elgazwy; Peter G Jones

doi:10.1107/S1600536814000427

. 2014 Jan 15;70(Pt 2):o141–o142. doi: 10.1107/S1600536814000427

A second polymorph of (Z)-3-amino-4-(2-phenylhydrazinylidene)-1H-pyrazol-5(4H)-one

Abdel-Sattar S Hamad Elgazwy ^a, Peter G Jones ^b,^*

PMCID: PMC3998306 PMID: 24764867

Abstract

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—H_hydrazine⋯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, space group P-1, whereas the previously reported form was monoclinic, space group P2₁/c [Elgemeie et al. (2013 ▶). Acta Cryst. E69, o187], with stepped layers and a significantly lower density.

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 ▶). graphic file with name e-70-0o141-scheme1.jpg

Experimental

Crystal data

C₉H₉N₅O
M _r = 203.21
Triclinic,
a = 6.4433 (4) Å
b = 7.4563 (5) Å
c = 10.1989 (6) Å
α = 80.005 (5)°
β = 81.271 (5)°
γ = 70.512 (5)°
V = 452.57 (5) Å³
Z = 2
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 100 K
0.40 × 0.35 × 0.15 mm

Data collection

Oxford Diffraction Xcalibur Eos diffractometer
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010 ▶) T _min = 0.948, T _max = 1.000
31042 measured reflections
2848 independent reflections
2649 reflections with I > 2σ(I)
R _int = 0.022

Refinement

R[F ² > 2σ(F ²)] = 0.037
wR(F ²) = 0.107
S = 1.04
2848 reflections
152 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.54 e Å⁻³
Δρ_min = −0.19 e Å⁻³

Data collection: CrysAlis PRO (Agilent, 2010 ▶); cell refinement: 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.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536814000427/zq2216sup1.cif

e-70-0o141-sup1.cif^{(20.2KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536814000427/zq2216Isup2.hkl

e-70-0o141-Isup2.hkl^{(139.8KB, hkl)}

Click here for additional data file.^{(4.1KB, cml)}

Supporting information file. DOI: 10.1107/S1600536814000427/zq2216Isup3.cml

CCDC reference: http://scripts.iucr.org/cgi-bin/cr.cgi?rm=csd&csdid=980594

Additional supporting information: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

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⋯O1^iv	0.893 (15)	2.185 (15)	3.0428 (10)	161.0 (13)

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) .

Acknowledgments

The authors acknowledge the financial support of the Ain Shams University, established and supported under the Egyptian Government Cooperative Research Centers Program.

supplementary crystallographic information

1. Comment

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.

2. Experimental

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%.