organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
nearly planar, apart from the 4-methoxy group at one end of
the molecule and the unsubstituted phenyl ring at the other
end (Table 3). The 4-methoxy group in (II) has its methyl
group twisted well out of the plane of the adjacent aryl ring,
presumably for steric reasons, whereas the methyl groups of
the 3- and 5-methoxy substituents are essentially coplanar
with this ring; the dihedral angle between phenyl ring C11±
ISSN 0108-2701
Hydrogen-bonded chains in
ꢀ
3
-(5-chloro-3-methyl-1-phenyl-1H-
C16 and the adjacent pyrazole ring is 53.1 (2) in (I) and
ꢀ
4
0.0 (2) in (II). Accordingly, the molecules of (I) and (II)
pyrazol-4-yl)-1-(4-methoxyphenyl)-
propenone and 3-(5-chloro-3-methyl-
have no internal symmetry and so are chiral, and in the
absence of inversion twinning each crystal of (I) thus contains
only one enantiomer.
1
-phenyl-1H-pyrazol-4-yl)-1-(3,4,5-
Consistent with the different conformations adopted by the
methoxy groups in (II), the pairs of exocyclic CÐCÐO angles
at both C53 and C55 show the difference typical of those
found in planar methoxyarenes, including (I), while the two
CÐCÐO angles at C54 have values which are much more
similar. Associated with this conformational difference in (II),
the CÐOÐC angles at O53 and O55 are much larger than that
at O54, and the CÐO distances, particularly those to the
methoxy atoms C5n1 (n = 3, 4 or 5), show signi®cant differ-
ences associated with the conformations. The remaining bond
lengths and angles show no unusual values. In particular, there
is no structural evidence for signi®cant charge polarization.
In each of (I) and (II), the molecules are linked into simple
chains by a single CÐHÁ Á ÁO hydrogen bond (Tables 2 and 4).
In compound (I), aryl atom C12 in the molecule at (x, y, z)
acts as hydrogen-bond donor to carbonyl atom O43 in the
trimethoxyphenyl)propenone
a
a
b
c
Jorge Trilleras, Jairo Quiroga, Justo Cobo, John N. Low
d
and Christopher Glidewell *
a
Grupo de Investigaci o n de Compuestos Heteroc Âõ clicos, Departamento de Qu Âõ mica,
b
Universidad de Valle, A.A. 25360 Cali, Colombia, Departamento de Qu Âõ mica
c
Inorg a nica y Org a nica, Universidad de Ja e n, 23071 Ja e n, Spain, Department of
Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen AB24 3UE,
d
Scotland, and School of Chemistry, University of St Andrews, Fife KY16 9ST,
Scotland
Received 4 May 2005
Accepted 5 May 2005
Online 31 May 2005
1
Molecules of 3-(5-chloro-3-methyl-1-phenyl-1H-pyrazol-4-yl)-
1
molecule at (1 � x, 2 + y, 1 � z), so forming a C(10) chain
-(4-methoxyphenyl)propenone, C H ClN O , (I), are
2
running parallel to the [010] direction and generated by the 2
1
0
17
2
2
linked into C(10) chains and molecules of 3-(5-chloro-
-methyl-1-phenyl-1H-pyrazol-4-yl)-1-(3,4,5-trimethoxyphen-
yl)propenone, C H ClN O , (II), are linked into C(14)
3
2
2
21
2
4
bc ho an i dn .s , in each case by means of a single CÐHÁ Á ÁO hydrogen
Comment
We report here the structures of two novel chalcones,
prepared by Claisen±Schmidt condensation reactions
betweeen 5-chloro-4-formyl-3-methyl-1-phenylpyrazole and
methoxy-substituted acetophenones.
Figure 1
The molecule of (I), showing the atom-labelling scheme. Displacement
ellipsoids are drawn at the 30% probability level and H atoms are shown
as small spheres of arbitrary radii.
With the exception of the unsubstituted phenyl ring C11±
C16, the molecular skeleton of compound (I) (Fig. 1) is nearly
planar, as shown by the leading torsion angles (Table 1).
Similarly, the molecular skeleton of compound (II) (Fig. 2) is
Figure 2
The molecule of (II), showing the atom-labelling scheme. Displacement
ellipsoids are drawn at the 30% probability level and H atoms are shown
as small spheres of arbitrary radii.
o414 # 2005 International Union of Crystallography
DOI: 10.1107/S0108270105014435
Acta Cryst. (2005). C61, o414±o416
Trilleras, Jorge
