organic compounds
Acta Crystallographica Section C
Crystal Structure
5-amino group to a formamidine function by condensation
with DMF.
Communications
ISSN 0108-2701
(E)-N2-{4-[(E)-2-(4-Chlorobenzoyl)-
ethenyl]-3-methyl-1-phenyl-1H-
pyrazol-5-yl}-N1,N1-dimethylform-
amidine: polarized molecules within
sheets of p-stacked hydrogen-bonded
chains
Jairo Quiroga,a Jorge Trilleras,b Michael B. Hursthouse,c
Justo Cobod and Christopher Glidewelle*
a
´
Departamento de Quımica, Universidad de Valle, AA 25360 Cali, Colombia,
b
´
´
´
Departamento de Quımica, Universidad del Atlantico, Km 7 vıa antigua Puerto
Colombia, Barranquilla, Colombia, cSchool of Chemistry, University of
Southampton, Highfield, Southampton SO17 1BJ, England, dDepartamento de
´
´
´
´
´
Quımica Inorganica y Organica, Universidad de Jaen, 23071 Jaen, Spain, and
eSchool of Chemistry, University of St Andrews, Fife KY16 9ST, Scotland
Correspondence e-mail: cg@st-andrews.ac.uk
Received 23 March 2010
Accepted 30 March 2010
Online 13 April 2010
The molecules of the title compound, C22H21ClN4O, are
conformationally chiral, and in the space group P212121 each
crystal contains only one conformational enantiomer. The
intramolecular dimensions provide evidence for polarization
of the electronic structure. Molecules are linked by a single
C—Hꢀ ꢀ ꢀꢀ(arene) hydrogen bond into chains, which are
themselves weakly linked into sheets by an aromatic ꢀ–ꢀ
stacking interaction.
The molecular conformation of (I) is conveniently consid-
ered in terms of the orientations of the various peripheral
substituents relative to the central pyrazole ring, as defined by
the relevant torsion angles (Table 1). Thus, while the chain
between atoms C4 and C41 (Fig. 1) is nearly coplanar with the
pyrazole ring, the two benzene rings are both markedly
twisted out of this plane: the dihedral angles between the
pyrazole ring and the C11–C16 and C41–C46 aryl rings are
25.1 (2) and 15.7 (2)ꢁ, respectively. Similarly, the dimethyl-
aminomethine unit is significantly twisted out of the plane of
the pyrazole ring, as shown by the value of the N1—C5—
N51—C52 torsion angle (Table 1). Consequently, the molecule
of (I) has no internal symmetry and hence it is chiral. In the
space group P212121, therefore, each crystal contains only a
single conformational enantiomer. However, this has no
chemical significance and it may be expected that, in solution,
for example, all accessible molecular conformations are
populated in a dynamic equilibrium.
Comment
We are exploring the use of 5-amino-4-formylpyrazoles as
building blocks in the synthesis of new heterocyclic
compounds containing fused pyrazole ring systems, as such
compounds have a wide range of potential applications
(Elguero, 1984, 1996). In connection with this synthetic study,
we report here the structure of the title compound, (I) (Fig. 1),
which forms an interesting structure consisting of ꢀ-stacked
hydrogen-bonded chains.
Compound (I) was prepared by base-catalysed condensa-
tion of 40-chloroacetophenone with the intermediate (E)-N2-
(4-formyl-3-methyl-1-phenyl-1H-pyrazol-5-yl)-N1,N1-dimethyl-
formamidine, denoted (A) in the scheme, which itself had
been prepared in a single step by reaction of the simple
precursor 5-amino-3-methyl-1-phenylpyrazole with an excess
of N,N-dimethylformamide (DMF) and OPCl3, in a process
which leads not only to formylation of the pyrazole ring at
the hitherto-vacant 4-position, but also to conversion of the
The intramolecular dimensions (Table 1) provide evidence
for polarization of the electronic structure. The C47—O47 and
C48—C49 bonds are both long for their types [mean values
˚
(Allen et al., 1987) = 1.222 and 1.340 A, respectively; upper
˚
quartile values = 1.229 and 1.348 A, respectively], while the
C47—C48 and C4—C49 bonds are both short for their types
˚
(mean values = 1.464 and 1.455 A respectively; lower quartile
Acta Cryst. (2010). C66, o245–o248
doi:10.1107/S0108270110012023
# 2010 International Union of Crystallography o245
Quiroga, Jairo
