4-(4-Chlorobenzylideneamino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one and 4-(2-chlorobenzylideneamino)-1,5-dimethyl-2-phenyl-1 H-pyrazol-3(2H)-one

Article abstract of DOI:10.1107/S0108270106021512

The two title compounds, both with formula C₁₈H ₁₆ClN₃O, are structurally similar Schiff bases derived from the condensation of 4-chlorobenzaldehyde or 2-chlorobenzaldehyde with 4-aminoantipyrine in methanol solution. As e

Full text of DOI:10.1107/S0108270106021512

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
and antiviral activities (Tarafder et al., 2002; Cukurovali et al.,
2002; Ali et al., 2002). Recently, the crystal structure of 4-[(2,4-
dichlorobenzylidene)amino]-1,5-dimethyl-2-phenyl-1,2-di-
hydropyrazol-3-one, (III), has been reported (Jing et al., 2005).
However, the in¯uence of the substituent groups on the crystal
structures of antipyrine derivatives has seldom been reported.
In this paper, the crystal structures and the substituent effects
of the two structurally similar title antipyrine derivatives, viz.
the para-substituted compound (I) and the ortho-substituted
compound (II), are reported.
ISSN 0108-2701
4-(4-Chlorobenzylideneamino)-1,5-
dimethyl-2-phenyl-1H-pyrazol-3(2H)-
one and 4-(2-chlorobenzylidene-
amino)-1,5-dimethyl-2-phenyl-1H-
pyrazol-3(2H)-one
The structures of (I) and (II) (Figs. 1 and 2) are analogous to
those of ortho- and para-substituted (III). The bond lengths
and angles in (I) and (II) are comparable to one another and
to the corresponding values in (III), and all lie within normal
ranges (Allen et al., 1987). The main difference between the
two structures is the position of the Cl atoms. In (I), atom Cl1
is located at the para position, and thus it cannot participate in
the formation of intramolecular hydrogen bonds, while in (II),
atom Cl1 is located at the ortho position, forming an intra-
molecular C7ÐH7Á Á ÁCl1 hydrogen bond (Table 2). In each of
Yu-Xi Sun,* Ran Zhang, Qing-Mai Jin, Xi-Jing Zhi and
Xiao-Ming Lu
È
Department of Chemistry, Qufu Normal University, Qufu 273165, People's Republic
of China
Correspondence e-mail: yuxisun@163.com
Ê
the compounds, the C7 N1 bond lengths [1.276 (2) A in (I)
Received 25 May 2006
Accepted 6 June 2006
Online 14 July 2006
Ê
and 1.278 (3) A in (II)] conform to the value for a double
Ê
bond. The distance between atoms C8 and N1 [1.392 (2) A in
The two title compounds, both with formula C18H16ClN3O, are
structurally similar Schiff bases derived from the condensation
of 4-chlorobenzaldehyde or 2-chlorobenzaldehyde with
4-aminoantipyrine in methanol solution. As expected, both
compounds adopt trans con®gurations about the central C
N
bonds. In the crystal structure of the 4-chloro analogue,
molecules are linked through weak CÐHÁ Á ÁO hydrogen
bonds, forming chains running along the a axis. In the crystal
structure of the 2-chloro analogue, molecules are linked
through weak CÐHÁ Á ÁO and CÐHÁ Á ÁCl hydrogen bonds,
forming layers parallel to the ab plane.
Figure 1
Comment
The structure of (I), showing the atom-numbering scheme. Displacement
ellipsoids are drawn at the 30% probability level. The intramolecular
hydrogen bond is shown as a dashed line.
Antipyrine and its derivatives exhibit a wide range of biolog-
ical activities and applications (Yadav et al., 2003; Ismail, 2000;
Abd El Rehim et al., 2001). A few crystal structures of anti-
pyrine derivatives have been investigated (Liang et al.,
Figure 2
2002; Li & Zhang, 2004, 2005; Zhang & Li, 2005). Schiff bases
have demonstrated signi®cant biological activity and new
examples are being tested for their antitumour, antimicrobial
The structure of (II), showing the atom-numbering scheme. Displacement
ellipsoids are drawn at the 30% probability level. Intramolecular
hydrogen bonds are shown as dashed lines.
Acta Cryst. (2006). C62, o467±o469
DOI: 10.1107/S0108270106021512
# 2006 International Union of Crystallography o467

organic compounds
both (I) and (II)] is intermediate between a CÐN single and a
In the crystal structure of (I), molecules are linked through
weak CÐHÁ Á ÁO hydrogen bonds (Table 1), forming chains
running along the a axis (Fig. 3). In the crystal structure of (II),
molecules are linked through weak CÐHÁ Á ÁO and CÐHÁ Á ÁCl
hydrogen bonds, forming layers parallel to the ab plane
(Fig. 4). The same pattern can be observed in (III), in which
the ortho Cl1 atom participates in the formation of inter-
molecular CÐHÁ Á ÁCl hydrogen bonds, while the para Cl2
atom does not participate in any hydrogen bonds.
In conclusion, in the chloro-substituted antipyrine Schiff
bases, the ortho Cl atom can participate in the formation of
both intra- and intermolecular hydrogen bonds; however, the
para Cl atom cannot participate in any hydrogen bonds. The
positions of substituent groups can signi®cantly in¯uence the
®nal structures.
C N double bond length, because of conjugation effects in
each of the molecules. The conjugation effects also cause the
pyrazoline and C1±C6 benzene rings to be nearly coplanar,
Ê
with a mean deviation from the overall plane of 0.0672 A in (I)
Ê
and 0.1125 A in (II). The dihedral angle between the C1±C6
benzene ring and the pyrazoline ring is 8.7 (2)ꢀ for (I) and
13.2 (2)ꢀ for (II). The dihedral angle between the C13±C18
phenyl ring and the pyrazoline ring is 51.6 (2)ꢀ for (I) and
75.5 (2)ꢀ for (II). As expected, the molecular structures adopt
trans con®gurations about the central C N bonds, which is
also observed in (III).
Experimental
For the preparation of (I), a mixture of 4-chlorobenzaldehyde
(0.1 mmol, 14.1 mg) and 4-aminoantipyrine (0.1 mmol, 20.3 mg) were
dissolved in methanol (10 ml). The mixture was stirred for about 1 h
at room temperature to give a clear yellow solution. After the solu-
tion had been kept in air for 3 d, yellow prism-shaped crystals were
formed. Compound (II) was prepared by a procedure similar to that
described for (I), with 4-chlorobenzaldehyde replaced by 2-chloro-
benzaldehyde (0.1 mmol, 14.1 mg). Yellow prism-shaped crystals of
(II) were obtained after evaporating the solution in air for 6 d.
Compound (I)
Figure 3
The molecular packing of (I), viewed along the a axis. Hydrogen bonds
are shown as dashed lines. H atoms not involved in the interactions shown
have been omitted.
Crystal data
C18H16ClN3O
Mr = 325.79
Orthorhombic, Pbca
Ê
a = 6.971 (1) A
b = 17.508 (1) A
Z = 8
Dx = 1.318 Mg m
Mo Kꢀ radiation
ꢁ = 0.24 mm
T = 298 (2) K
Prism, yellow
0.35 Â 0.20 Â 0.17 mm
3
1
Ê
Ê
c = 26.905 (2) A
Ê
V = 3283.7 (6) A
3
Data collection
Bruker SMART APEX area-
detector diffractometer
' and ! scans
Absorption correction: multi-scan
(SADABS; Bruker, 2002)
Tmin = 0.921, Tmax = 0.960
24843 measured re¯ections
3402 independent re¯ections
2620 re¯ections with I > 2ꢂ(I)
Rint = 0.037
ꢃmax = 26.5ꢀ
Re®nement
Re®nement on F2
R[F2 > 2ꢂ(F2)] = 0.048
wR(F2) = 0.126
S = 1.04
3402 re¯ections
w = 1/[ꢂ2(F2o) + (0.0573P)2
+ 0.8176P]
where P = (F2o + 2Fc2)/3
(Á/ꢂ)max < 0.001
3
Ê
Áꢄmax = 0.20 e A
3
Ê
0.28 e A
210 parameters
H-atom parameters constrained
Áꢄmin
=
Table 1
Hydrogen-bond geometry (A, ) for (I).
ꢀ
Ê
DÐHÁ Á ÁA
DÐH
HÁ Á ÁA
DÁ Á ÁA
DÐHÁ Á ÁA
C4ÐH4Á Á ÁO1i
C11ÐH11AÁ Á ÁO1ii
0.93
0.93
0.96
2.43
2.33
2.47
3.219 (2)
3.016 (2)
3.407 (5)
143
130
165
Figure 4
C7ÐH7Á Á ÁO1
The molecular packing of (II), viewed along the a axis. Hydrogen bonds
are shown as dashed lines. H atoms not involved in the interactions shown
have been omitted.
Symmetry codes: (i) x ‡ 1; y ‡ 2; z ‡ 1; (ii) x ‡ 1; y; z.
Acta Cryst. (2006). C62, o467±o469
ꢁ
o468 Sun et al. C18H16ClN3O

organic compounds
Compound (II)
All H atoms in (I) and (II) were placed in geometrically idealized
positions and constrained to ride on their parent atoms, with CÐH
Ê
distances in the range 0.93±0.96 A and with Uiso(H) values of 1.2 or
Crystal data
3
1.5 times Ueq(C). The Flack (1983) parameter value for (II) is based
on the `hole-in-one' re®nement method.
C18H16ClN3O
Mr = 325.79
Orthorhombic, P212121
Dx = 1.317 Mg m
Mo Kꢀ radiation
ꢁ = 0.24 mm
T = 298 (2) K
1
For both compounds, data collection: SMART (Bruker, 2002); cell
re®nement: SAINT-Plus (Bruker, 2002); data reduction: SAINT-
Plus; program(s) used to solve structure: SHELXS97 (Sheldrick,
1997); program(s) used to re®ne structure: SHELXL97 (Sheldrick,
1997); molecular graphics: SHELXTL (Bruker, 2002); software used
to prepare material for publication: SHELXTL.
Ê
a = 6.848 (1) A
Ê
b = 13.654 (2) A
Prism, yellow
0.25 Â 0.18 Â 0.18 mm
Ê
c = 17.567 (2) A
Ê
V = 1642.6 (4) A
Z = 4
3
Data collection
Bruker SMART APEX area-
detector diffractometer
' and ! scans
Absorption correction: multi-scan
(SADABS; Bruker, 2002)
Tmin = 0.942, Tmax = 0.958
11680 measured re¯ections
3377 independent re¯ections
2979 re¯ections with I > 2ꢂ(I)
Rint = 0.026
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: SK3029). Services for accessing these data are
described at the back of the journal.
ꢃmax = 26.5ꢀ
References
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Phys. 70, 268±273.
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A. M. (2002). J. Inorg. Biochem. 92, 141±148.
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R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1±83.
Re®nement
Re®nement on F2
R[F2 > 2ꢂ(F2)] = 0.042
wR(F2) = 0.107
S = 1.04
3377 re¯ections
211 parameters
H-atom parameters constrained
w = 1/[ꢂ2(Fo2) + (0.0492P)2
+ 0.2996P]
where P = (Fo + 2Fc2)/3
(Á/ꢂ)max < 0.001
3
Ê
Áꢄmax = 0.29 e A
3
Ê
0.25 e A
Áꢄmin
=
Extinction correction: SHELXL97
Extinction coef®cient: 0.043 (3)
Absolute structure: Flack (1983),
1415 Friedel pairs
Bruker (2002). SMART (Version 5.618), SAINT-Plus (Version 6.02a),
SADABS (Version 2.03) and SHELXTL (Version 5.03). Bruker AXS
Inc., Madison, Wisconsin, USA.
Flack parameter: 0.01 (10)
È
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2
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Table 2
Hydrogen-bond geometry (A, ) for (II).
ꢀ
Ê
DÐHÁ Á ÁA
DÐH
HÁ Á ÁA
DÁ Á ÁA
DÐHÁ Á ÁA
C2ÐH2Á Á ÁO1i
C3ÐH3Á Á ÁCl1i
C7ÐH7Á Á ÁCl1
C7ÐH7Á Á ÁO1
C11ÐH11CÁ Á ÁO1ii
0.93
0.93
0.93
0.93
0.96
2.57
2.82
2.67
2.35
2.50
3.491 (3)
3.713 (3)
3.053 (3)
3.015 (3)
3.435 (3)
172
161
106
128
163
Symmetry codes: (i) x ‡ 1; y ‡ 12; z ‡ 21; (ii) x ‡ 1; y; z.
ꢁ
Acta Cryst. (2006). C62, o467±o469
Sun et al. C18H16ClN3O o469