Isomorphism in two (E)-1-(4-halophenyl)-N-[1-(4-methylphenyl)-1H-imidazol- 4-yl]methanimines (halide 5 Cl, Br)

Article abstract of DOI:10.1007/s10870-012-0354-1

The crystal structures of two imidazole-4-imines, (E)-1-(4-chlorophenyl)-N- [1-(4-methylphenyl)-1H-imidazol- 4-yl]methanimine (1, C₁₇H ₁₄ClN₃), and (E)-1-(4- bromophenyl)-N-[1-(4-methylphenyl)- 1H-imidazol-4-yl] methanimin

Full text of DOI:10.1007/s10870-012-0354-1

J Chem Crystallogr (2012) 42:1036–1041
DOI 10.1007/s10870-012-0354-1
ORIGINAL PAPER
Isomorphism in Two (E)-1-(4-Halophenyl)-N-[1-(4-
Methylphenyl)-1H-Imidazol-4-yl]Methanimines (Halide 5 Cl, Br)
•
Hanna Skrzypiec Radosław Mazurek
•
•
Paweł Wagner Maciej Kubicki
Received: 14 February 2012 / Accepted: 4 August 2012 / Published online: 24 August 2012
Ó The Author(s) 2012. This article is published with open access at Springerlink.com
Abstract The crystal structures of two imidazole-4-imines,
(E)-1-(4-chlorophenyl)-N-[1-(4-methylphenyl)-1H-imida-
zol-4-yl]methanimine (1, C17H14ClN3), and (E)-1-(4-
bromophenyl)-N-[1-(4-methylphenyl)-1H-imidazol-4-yl]
methanimine, (2, C17H14BrN3), are isomorphous, the iso-
structurality index is 99.4 %. Both compounds crystallize
in the triclinic space group P-1 with unit cell parameters at
bonds and by p–p interactions. This study illustrates the
significant role of the weak interactions, which—in spite of
their weakness—can robustly repeat in the crystal struc-
tures of similar compounds.
Keywords Imidazole ꢀ Isostructuralism ꢀ Multiple
molecules ꢀ Weak intermolecular interactions ꢀ Crystal
structure
˚
100(1) K as follows: for (1), a = 7.9767(5) A, b =
˚
˚
10.9517(7) A, c = 16.6753(12) A, a = 80.522(6)°, b =
˚
87.046(6)°, c = 89.207(5)°, and for (2), a = 8.0720(7) A,
˚
˚
b = 10.9334(10) A, c = 16.8433(13) A, a = 81.161(7)°,
b = 86.605(7)°, c = 89.505(7)°. The structures contain
two symmetry—independent but conformationally similar
molecules in the asymmetric unit (Z’ = 2). In both com-
pounds the overall twist of the molecule, defined as the
dihedral angle between the terminal phenyl ring planes is
significant, around 56°. The crystal packing is determined
mainly be weak specific intermolecular interactions: the
C–HꢀꢀꢀN hydrogen bonds connect molecules into infinite
chains, and the chains are linked via C–HꢀꢀꢀX hydrogen
Introduction
Nucleophilic substitution of the nitroimidazole system
proved to be a versatile tool for modification of the imid-
azole moiety [1, 2]. The presence of the nitro group,
essential for the reaction mentioned, becomes not only
unnecessary but it can interfere with the next potential
synthetic transformation. The reduction of the nitro group,
relatively easy in benzene derivatives, has proven chal-
lenging in azole systems due to metastability of the
resulting amines [3, 4]. To this end the reduction and fur-
ther protection of the nitro functionality appears to be an
important synthetic problem.
H. Skrzypiec ꢀ M. Kubicki (&)
Quite interestingly it turned out that in the Cambridge
Structural Database [5] there are only a few examples of
4-aminoimidazoles. Among those there is only one imine-
derivative, ethyl 5-(4-methyl-3-phenyl-3H-thiazol-2-ylide-
neamino)-3-propyl-3H-imidazole-4-carboxylate [6], seven
diaza-compounds (e.g., series of phenylazoimidazoles [7]),
and one primary, six secondary, and 12 tertiary amines.
During our studies on imidazole derivatives we have
determined the structures of some imidazole-4-imines.
Here we report the results of the analysis of two compounds
(Scheme 1, Figs. 1, 2), namely (E)-1-(4-chlorophenyl)-
N-[1-(4-methylphenyl)-1H-imidazol-4-yl]methanimine, (1),
Department of Chemistry, Faculty of Chemistry, Adam
´
Mickiewicz University, Grunwaldzka 6, 60-780 Poznan, Poland
e-mail: mkubicki@amu.edu.pl
R. Mazurek
Institute of Organic Chemistry and Technology, The Silesian
University of Technology, Krzywoustego 4, 44-100 Gliwice,
Poland
P. Wagner
Intelligent Polymer Research Institute, ARC Centre of
Excellence for Electromaterials Science, University of
Wollongong, Northfields Avenue, Wollongong, NSW 2522,
Australia
123

J Chem Crystallogr (2012) 42:1036–1041
1037
Scheme 1 Chemical formulae for compounds 1 and 2
and (E)-1-(4-bromophenyl)-N-[1-(4-methylphenyl)-1H-imidazol-
4-yl]methanimine.
Results and Discussion
Compounds (1) and (2) are isostructural. It is possible to
estimate the degree of isostructuralism using the descrip-
´ ´
tors introduced by Kalman et al. [8] in his work on so-
called ‘‘main-part’’ isostructuralism, or a more specific
´
index defined by Kubicki and Szafranski [9]. The unit-cell
similarity index is 0.01, very close to the ideal value of 0.
Also the values of both isostructurality indices are close to
the ideal values: according to [8] 99.3 % (ideal value
100 %), and according to [9] 0.985 (ideal value 1.0). The
isostructuralism can be seen in the almost identical packing
diagrams (Fig. 3).
Both compounds crystallize with two symmetry-inde-
pendent molecules A and B in the asymmetric part of the
unit cell. The results of the normal probability plot analysis
[10, 11] for bond lengths and angles show that there are no
Fig. 3 Crystal packing of a 1 and b 2, as seen along x-direction.
Different colors denote symmetry-independent molecules (Color
figure online)
Fig. 1 Anisotropic ellipsoid
representation of molecule 1A
together with atom labelling
scheme. The ellipsoids are
drawn at 50 % probability level,
hydrogen atoms are depicted as
spheres with arbitrary radii.
Hydrogen bonds are drawn as
dashed lines
Fig. 2 Anisotropic ellipsoid
representation of molecule 2A
together with atom labelling
scheme. The ellipsoids are
drawn at 50 % probability level,
hydrogen atoms are depicted as
spheres with arbitrary radii
123

1038
J Chem Crystallogr (2012) 42:1036–1041
Table 1 Selected geometrical
˚
1A
1.375(4)
1B
1.375(4)
2A
1.371(4)
2B
1.371(4)
data (A, °) with su’s in
parentheses
N1–C2
N1–C5
1.372(4)
1.416(4)
1.294(4)
1.392(4)
1.392(4)
1.264(4)
1.459(5)
1.737(3)
119.1(3)
117.1(3)
104.3(3)
119.0(3)
122.7(3)
118.6(3)
121.4(3)
-147.9(3)
31.0(5)
1.374(4)
1.415(4)
1.305(4)
1.391(4)
1.381(5)
1.273(4)
1.457(5)
1.737(4)
119.2(3)
117.4(3)
104.6(3)
119.5(3)
121.6(3)
118.3(3)
120.8(3)
-147.9(3)
31.1(5)
1.378(4)
1.422(4)
1.300(4)
1.393(4)
1.391(4)
1.280(4)
1.458(4)
1.899(3)
119.4(3)
117.0(3)
104.7(3)
118.6(3)
122.3(3)
118.5(3)
121.9(3)
-147.7(3)
30.9(4)
1.380(4)
1.421(4)
1.306(4)
1.392(4)
1.393(4)
1.273(4)
1.466(4)
1.901(3)
119.9(3)
118.1(3)
104.3(3)
119.1(3)
120.7(3)
118.1(3)
121.6(3)
-148.8(3)
30.8(4)
N1–C11
C2–N3
N3–C4
C4–N41
N41–C42
C42–C43
C46–Cl1(Br1)
C12–C11–C16
C13–C14–C15
C2–N3–C4
C4–N41–C42
N41–C42–C43
C44–C43–C48
C45–C46–C47
C5–N1–C11–C16
C5–N1–C11–C12
C5–C4–N41–C42
N3–C4–N41–C42
C4–N41–C42–C43
N41–C42–C43–C44
N41–C42–C43–C48
A/B
-170.0(3)
9.4(5)
-169.9(3)
9.5(5)
-169.4(3)
10.3(4)
-168.8(3)
9.7(4)
180.0(3)
-161.1(3)
18.0(5)
178.4(3)
-160.7(3)
17.6(5)
-179.7(3)
-160.9(3)
17.5(4)
178.6(3)
-160.5(3)
17.8(5)
31.30(14)
9.7(2)
31.56(14)
9.6(2)
31.28(12)
10.6(2)
31.61(13)
10.3(2)
B/C
C/D
18.5(4)
18.5(3)
18.6(3)
19.0(3)
Planes A, B, C, and D are
defined in text and in Fig. 1
A/D
55.79(9)
54.67(9)
56.44(8)
55.85(8)
systematic differences between the molecules, and the
actual differences are only of a statistical nature: R2 cor-
relation factors for bond lengths are 0.95 (1) and 0.97 (2),
while for bond angles: 0.97(1) and 0.97(2).
can be found that the ‘sense’ of the twists between the sub-
sequent planes is the same, and the overall twist is roughly
equal to the sum of the individual angles.
The crystal packing is determined mainly by the spe-
cific, directional weak interactions. The main motif, an
*ABAB* chain along [010] direction, is created by rel-
atively short and linear C5–HꢀꢀꢀN3 hydrogen bonds (Fig. 4;
Table 2). In the high resolution structure of 1-phenyl-4-
nitroimidazole [14] the topological analysis of the electron
density distribution showed the critical points connected to
the identical C5–HꢀꢀꢀN3 hydrogen bonds. The neighboring
chains are connected along [101], the long axis of the
molecule, by very weak C–HꢀꢀꢀX and C–Hꢀꢀꢀp hydrogen
bonds (Table 2; Fig. 5).
Due to the isostructurality, the discussion can be made
on one of the compound only (1), the geometrical values
for the second one (2) will be given in square brackets.
The bond lengths and angles pattern is typical; the short
N41–C42 bonds prove the double-bond character. The intra-
annular bond angles within the phenyl rings reflect the nature
ofthesubstituents, generallyinaccordancewiththefindingsof
¨
Domenicano and Murray-Rust [12] and Exner and Bohm [13].
The conformation of the molecule can be described by the
dihedral angles between the subsequent planar fragments:
methylphenyl group (A), imidazole ring (B), CꢁN CꢁC
bridge (C) and halophenyl group (D). All these groups are
essentially planar, maximum deviation from the least-
Experimental
˚
˚
squares plane is as small as 0.006(2) A [0.013(3) A]. The
overall twist, defined as the dihedral angle between the ter-
minal phenyl rings, is 55.79(9)° (56.44(8)°) in molecule A
and 54.67(9)° (55.85(8)°) in molecule B. The values of the
selected dihedral and torsion angles are listed in Table 1. It
Preparation of Compounds
1-(4-Methylphenyl)-4-nitroimidazole was reduced in a
current of hydrogen under atmospheric pressure at room
123

J Chem Crystallogr (2012) 42:1036–1041
1039
Fig. 4 The *ABAB* chain of the crystal structures, in the case of 1. Hydrogen bonds are drawn as dashed lines
Table 2 Intermolecular
1
˚
interaction data (A, 8) with su’s
in parentheses
D
H
A
D–X
0.95
0.95
0.98
0.98
0.98
0.95
0.95
0.95
HꢀꢀꢀA
2.40
2.49
3.07
3.06
2.96
2.81
2.78
2.77
DꢀꢀꢀA
D–HꢀꢀꢀA
173
C5A
C5B
C141
C142
C141
C44A
C16B
C47B
2
H5A
H5B
N3Ba
N3Ab
Cl1Ac
Cl1Bd
CgDAe
CgAAf
CgDBf
CgABg
3.342(4)
3.415(4)
3.830(4)
3.567(4)
3.901(5)
3.558(4)
3.475(4)
3.456(5)
164
H14A
H14F
H14C
H44A
H16B
H47B
135
113
160
137
130
130
D
H
A
D–X
0.95
0.95
0.98
0.98
0.98
0.95
0.95
0.95
HꢀꢀꢀA
2.38
2.48
3.20
3.09
3.00
2.82
2.83
2.76
DꢀꢀꢀA
D–HꢀꢀꢀA
173
C5A
C5B
C141
C142
C141
C44A
C16B
C47B
H5A
H5B
N3Ba
N3Ab
Br1Ac
Br1Bd
CgDAe
CgAAf
CgDBf
CgABg
3.327(4)
3.407(4)
3.870(3)
3.590(3)
3.889(4)
3.581(4)
3.510(4)
3.459(4)
CgA and CgD denote middle
point of rings A and D (cf. text);
C141 and C142 are the methyl
atoms from molecules A and B,
respectively
165
H14A
H14F
H14C
H44A
H16B
H47B
127
113
152
a
Symmetry codes: x,-1 ? y,
b
-1 ? z; x,y,1 ? z; -1-x,
c
138
d
-y,-z; 1 ? x,y,1 ? z;
130
f
e-x,-y,-z; -x,1-y,1-z;
131
g-x,1-y,2-z
temperature in methanol as a solvent. Freshly prepared
Raney nickel was used as a catalyst. The TLC analysis
showed that the starting material was consumed within an
hour giving an undefined intermediate. The reaction was
carried out until the entire intermediate compound was
reacted out—usually 6 h. After filtering off the metal cat-
alyst, because of its reactivity [2, 3], the resulting amine,
was not worked out but immediately treated with aromatic
123

1040
J Chem Crystallogr (2012) 42:1036–1041
Fig. 5 The molecules of 2, connected by weak interactions that involve p electrons (see text for details). The interactions are drawn as dashed
lines
Table 3 continued
Table 3 Crystal data, data collection and structure refinement
Compound
1
2
Compound
1
2
Reflections:
Collected
Formula
C
17H14ClN3
C17H14BrN3
340.22/c
Triclinic
P-1
14,462
5,042 (0.046)
3,930
21,242
5,151 (0.047)
4,226
Formula weight
Crystal system
Space group
295.76
Unique (Rint
)
Triclinic
P-1
With I [ 2r(I)
No. of parameters
Weighting scheme:
A
˚
a(A)
379
381
7.9767(5)
10.9517(7)
16.6753(12)
80.522(6)
87.046(6)
89.207(5)
1,434.91(16)
4
8.0720(7)
10.9334(10)
16.8433(13)
81.161(7)
86.605(7)
89.505(7)
1,466.3(2)
4
˚
b(A)
˚
c(A)
0.0696
1.7884
0.069
0.0413
1.1021
0.038
B
a(°)
b(°)
c(°)
R(F) [I [ 2r(I)]
wR(F2) [I [ 2r(I)]
R(F) (all data)
wR(F2) (all data)
Goodness of fit
0.164
0.086
3
˚
0.091
0.051
V(A )
0.173
0.091
Z
dx(g cm-3
)
1.367
1.541
1.11
1.05
-3
˚
Max/min Dq (e A
)
0.43/-0.50
0.65/-0.51
F(000)
l (mm-1
616
688
)
0.26
2.80
H range (°)
hkl range
2.08–25.00
-9 B h B 9
-13 B k B 12
-19 B l B 19
2.08–25.00
-9 B h B 9
-13 B k B 12
-20 B l B 20
aldehydes. The addition of a catalytic amount of acetic acid
caused the precipitation of the corresponding Schiff’s bases
in good yields.
123

J Chem Crystallogr (2012) 42:1036–1041
Crystallography
1041
Open Access This article is distributed under the terms of the
Creative Commons Attribution License which permits any use, dis-
tribution, and reproduction in any medium, provided the original
author(s) and the source are credited.
Diffraction data were collected at 100(1) K by the x-scan
technique on an Agilent Xcalibur CCD-detector diffrac-
tometer with Sapphire detector and using graphite-mono-
˚
chromatized Mo Ka radiation (k = 0.71073 A). The data
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