organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
the substituents on N1, C2, C4 and C5 were 4-methoxyphenyl
groups, and the calculated dihedral angles between the phenyl
moieties and the imidazole ring were 105.9 (substituent on
ISSN 0108-2701
N1), 15.1 (substituent on C2), 47.9 (substituent on C4) and
ꢀ
1
01.9 (substituent on C5). Thus, with respect to (I), a signif-
icantly different conformation is observed for the groups
bonded to the imidazole core. However, it cannot be deter-
mined whether these variations are related to the fact that (I)
is a non-symmetrical substituted imidazole or result from
stacking effects in the solid state.
The fourth substituent in (I) is a methyl group bonded to
C2, which has the methyl H atoms disordered over two
orientations. Two of the shorter intramolecular contacts
involve atom H12D of the minor disorder component and a
neighbouring phenyl ring on N1 (intramolecular contact
2
-Methyl-1,4,5-triphenyl-1H-
imidazole
a
b
Rosa A. V a zquez Garc Âõ a, Sylvain Bern eÁ s, * Ren eÂ
Guti e rrez P e rez and Marcos Mart Âõ nez Garc Âõ a
a
c
a
Centro de Investigaci o n, Facultad de Ciencias Qu Âõ micas, Benem e rita Universidad
b
Aut o noma de Puebla, AP 1067, 72001 Puebla, Pue., Mexico, Centro de Qu Âõ mica,
Instituto de Ciencias, Universidad Aut o noma de Puebla, AP 1613, 72000 Puebla,
c
Pue., Mexico, and Instituto de Qu Âõ mica, Universidad Nacional Aut o noma de
Ê
Ê
distances are C6Á Á ÁH12D 2.64 A and C7Á Á ÁH12D 2.61 A).
Such contacts may not exist in solution, but if they do, they are
weak enough to allow free rotation of the methyl group in
solution at room temperature, in agreement with the sharp
singlet observed in NMR for these H atoms at ꢂ 2.35 p.p.m.
M e xico, 04510 M e xico, DF, Mexico
Received 3 September 2002
Accepted 6 September 2002
Online 30 September 2002
(200 MHz, CDCl3).
In 2-methyl-1,4,5-triphenyl-1H-imidazole, C H N , the three
2
2
2
18
substituent phenyl groups are not delocalized with the
imidazole moiety; the dihedral angles these phenyl groups
form with the imidazole ring are in the range 25.90 (5)±
ꢀ
6
3.49 (6) .
Comment
During the synthesis of a large series of chiral ꢀ-diimines by
condensation of ꢀ-diketones with chiral primary amines
following a known procedure (Mehrotra & Singh, 1980), we
obtained the title compound, (I), as an unexpected by-product
(
see Experimental).
Figure 1
The structure of (I), with displacement ellipsoids at the 30% probability
level. H atoms are shown as small spheres of arbitrary radii. For the C12-
methyl group, the H atoms corresponding to the minor component of the
disorder have been omitted.
Compound (I) (Table 1, Fig. 1) is a tetrasubstituted
imidazole. The imidazole ring presents the common aromatic
geometry, with delocalized C N and C C ꢁ bond lengths in
Ê
the range 1.3123 (16)±1.3950 (16) A. Due to the substitution
at N1, no tautomeric forms are possible for the imidazole
moiety, in the solid state or in solution.
The packing of the molecule of (I) in the solid state is
determined by the low Laue symmetry and the above-
mentioned conformation of the phenyl groups. These two
features prevent any signi®cant stacking intermolecular
interactions in the cell; the shortest interaction between rings
.
. .
. . .
Ê
is 4.26 A, for two symmetry-related imidazole rings (symmetry
The phenyl groups bonded to atoms N1, C4 and C5 are not
delocalized with the imidazole ring; the dihedral angles
between the least-squares planes of the imidazole and phenyl
code: 1 � x, 1 � y, 1 � z). On the other hand, the lack of
suitable donor groups for hydrogen bonding favours the
separation of the molecules in the cell. The shortest observed
intermolecular contact is through the non-substituted
ꢀ
rings are 63.49 (6), 25.90 (5) and 58.75 (6) for the C6±C11,
i
C13±C18 and C19±C24 rings, respectively. This relative
conformation for the phenyl rings seems to minimize steric
hindrance in the overall molecule. A similar non-conjugated
arrangement was previously observed for a symmetrically
tetrasubstituted imidazole (Buttke et al., 1997). In this case,
imidazole N atom, viz. C7ÐH7Á Á ÁN3 [symmetry code: (i)
1 � x, 1 � y, 1 � z], with a long HÁ Á ÁN contact distance of
Ê
ꢀ
2.58 A and a contact angle of 167 . A consequence of this
packing structure is a relatively low packing index (Spek,
1998) of 66.1% for this small molecule.
Acta Cryst. (2002). C58, o619±o620
DOI: 10.1107/S0108270102016220
# 2002 International Union of Crystallography o619
Vazquez Garcia, Rosa A.
