Three polymorphs of 4-4′-diiodobenzalazine, and 4-chloro-4′- iodo-benz-alazine

Article abstract of DOI:10.1107/S0108270107034786

Three polymorphs of 4,4′-diiodobenzalazine (systematic name: 4-iodo-benzaldehyde azine), C14H10I2N2, have crystallographically imposed inversion symmetry. 4-Chloro-4′-iodobenzalazine [systematic name: 1-(4-chloro-benzyl-idene)-2-(4-iodo-benzyl-idene)diaza

Full text of DOI:10.1107/S0108270107034786

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
was expanded to include (Br,Cl), (I,Cl) and (I,Br) to see if
these were isostructural with one or another of the (X,X)
compounds.
ISSN 0108-2701
Fig. 1 shows the atom labeling and the anisotropic dis-
placement ellipsoid plots for (I,I-A) and (I,Cl). Molecules of
Three polymorphs of 4-40-diiodo-
benzalazine, and 4-chloro-40-iodo-
benzalazine
Charles R. Ojala,a William H. Ojala,b Doyle Brittonc* and
Christopher J. Cramerc,d
aDepartment of Chemistry, Normandale Community College, Bloomington,
MN 55431, USA, bDepartment of Chemistry, University of St Thomas, St Paul,
MN 55105, USA, cDepartment of Chemistry, University of Minnesota, Minneapolis,
MN 55455, USA, and dSupercomputing Institute, University of Minnesota,
Minneapolis, MN 55455, USA
Correspondence e-mail: britton@chem.umn.edu
Figure 1
Received 17 May 2007
Accepted 17 July 2007
Online 9 August 2007
Top: the molecular structure of (I,I-A). Displacement ellipsoids are
shown at the 50% probability level. Only the crystallographically unique
atoms are labeled. The labelings for (I,I-B) and (I,I-C) are the same and
the displacement ellipsoids are similar. Bottom: the molecular structure
of (I,Cl). Only the major component of the disorder [fraction equal to
0.586 (2)] is shown in full, with displacement ellipsoids at the 50%
probability level. The minor component is shown only in outline. The
ellipsoids in the minor component are constrained to be identical to those
of the overlapping atoms in the major component. The two components
lie on a pseudosymmetry center in the space group Pc.
Three polymorphs of 4,40-diiodobenzalazine (systematic
name: 4-iodobenzaldehyde azine), C14H10I2N2, have crystal-
lographically imposed inversion symmetry. 4-Chloro-40-iodo-
benzalazine [systematic name: 1-(4-chlorobenzylidene)-2-(4-
iodobenzylidene)diazane], C14H10ClIN2, has a partially disor-
dered pseudocentrosymmetric packing and is not isostructural
with any of the polymorphs of 4,40-diiodobenzalazine. All
structures pack utilizing halogen±halogen interactions; some
also have weak ꢀ (benzene ring) interactions. A comparison
with previously published methylphenylketalazines (which
differ by substitution of methyl for H at the azine C atoms)
shows a fundamentally different geometry for these two
classes, namely planar for the alazines and twisted for the
ketalazines. Density functional theory calculations con®rm
that the difference is fundamental and not an artifact of
packing forces.
Comment
In this paper, the descriptor (X,Y) is used as an abbreviation
for 4-X-40-Y-benzalazine, with the three title polymorphs
designated as (I,I-A), (I,I-B) and (I,I-C). Crystals of the
dichloro and dibromo analogs, viz. (Cl,Cl) and (Br,Br), of the
title compound, (I,I), are not isostructural (Zheng et al., 2005;
Figure 2
Top: one layer of the structure of (I,I-A), viewed normal to (100). The
intermolecular IÁ Á ÁI contacts are shown as dashed lines; these interactions
lie across centers of symmetry. Bottom: three layers viewed along [102].
The middle layer in this view is the layer shown in the top view.
Marignan et al., 1972). The determination of the structure of
(I,I) was undertaken to compare the packing with that of
(Br,Br). When three polymorphs of (I,I) were found, the study
o518 # 2007 International Union of Crystallography
DOI: 10.1107/S0108270107034786
Acta Cryst. (2007). C63, o518±o523

organic compounds
(I,I-A) lie on a center of symmetry. (I,Cl) is disordered about a
pseudo-center of symmetry, with 0.586 (2) as the fraction for
the major component of the disorder. In both structures, the
bond lengths and angles are normal. The labelings for all of
the compounds described here are the same; the anisotropic
displacement ellipsoids for (I,I-B) and (I,I-C) are similar to
those of (I,I-A).
The packing of (I,Cl) is shown in Fig. 5. The disordered
molecules (as noted above) assemble in layers held together
by IÁ Á ÁI, IÁ Á ÁCl or ClÁ Á ÁCl interactions. The molecules are
tilted by 59.9 (1)ꢀ away from the mean plane. All of the
molecules in a given layer have the same tilt; those in the
adjacent layer tilt in the opposite sense. This leads to a
herring-bone pattern between the layers. There are two kinds
of IÁ Á ÁI interactions, one lying across a 21 axis and the other
lying along the b axis. There is some similarity in this respect
between the packing arrangements of (I,Cl) and (I,I-C).
Schmidt (1971) showed that dichloro aromatic compounds
The packing of (I,I-A) is shown in Fig. 2. The molecules
assemble in ribbons held together by IÁ Á ÁI interactions and
parallel to the [102] direction. The ribbons form sheets normal
to the b axis, with the essentially planar molecules tilted by
33.4 (1)ꢀ away from the plane of the sheet. Adjacent sheets
form a herring-bone pattern. Table 1 gives the geometric data
for all of the IÁ Á ÁI contacts.
Ê
often crystallize with a short (approximately 4 A) axis,
presumably, in part, as a consequence of weak intermolecular
ClÁ Á ÁCl interactions. Sakurai et al. (1963) pointed out two
other kinds of ClÁ Á ÁCl interactions, viz. an approximately
linear arrangement across a center of symmetry, and an
angular arrangement across a 21 axis or a glide plane. These
interactions have been discussed by Desiraju (1987, 1989,
1995). Examples of all of these are shown in the four
compounds reported here. (I,I-A) has the approximately
linear arrangement across a center of symmetry. (I,I-B),
(I,I-C) and (I,Cl) all adopt the angular arrangement across a 21
axis. In addition, (I,Cl) and (I,I-C) have short axial contacts of
the type described by Schmidt (1971). The distances and
angles for all of the XÁ Á ÁX interactions are listed in Table 1.
Also included in Table 1 are the same data for the compounds
(X,X)*, where X = Cl, Br or I and * denotes the analogous
The packing of (I,I-B) is shown in Fig. 3. The molecules
assemble in layers held together by IÁ Á ÁI interactions and
parallel to the (103) plane. The molecules are tilted by
34.9 (1)ꢀ away from the mean plane of the layer; alternate
molecules are tilted in opposite directions away from the
plane.
The packing of (I,I-C) is shown in Fig. 4. The molecules
assemble in layers held together by IÁ Á ÁI interactions and
parallel to the (104) plane. The molecules are tilted by
58.6 (1)ꢀ away from the mean plane of the layer; alternate
molecules are tilted in opposite directions away from the
plane. There are two kinds of IÁ Á ÁI interactions, one lying
across a 21 axis and the other lying along the b axis.
Figure 4
Figure 3
Top: one layer of the structure of (I,I-C), viewed normal to (104). There
are two kinds of intermolecular IÁ Á ÁI contacts: one, shown by dashed
lines, zigzags about a 21 axis, while the other, shown by dotted lines, lies
along the b axis. Bottom: three layers viewed along b. The middle layer in
this view is the layer shown in the top view.
Top: one layer of the structure of (I,I-B), viewed normal to (103). The
intermolecular IÁ Á ÁI interactions are shown as dashed lines; they zigzag
about a 21 axis. Bottom: three layers viewed along b. The middle layer in
this view is the layer shown in the top view.
ꢁ
Acta Cryst. (2007). C63, o518±o523
Ojala et al. C14H10I2N2 and C14H10ClIN2 o519

organic compounds
molecules in which the aliphatic H atoms have been replaced
by methyl groups (the methylphenylketalazines, hereafter
referred to as simply ketalazines). In this latter series, the
XÁ Á ÁX distances are signi®cantly shorter in every case apart
from the (I,I) case.
minima predicted for the symmetrically related twisted
geometries and a more stable planar minimum predicted for
the fully planar geometry (i.e. having a CNNC torsion angle of
180ꢀ). In each instance, the torsional potential is relatively ¯at
over the range 75±285ꢀ; the total variation in energy is only
about 2 kcal mol 1. The methyl groups in the ketalazine
experience unfavorable steric repulsion that causes the energy
in this system to rise steeply outside this range. A full rota-
tional coordinate for the benzalazine system was computed;
the energy of the system having a C NÐN C torsion angle
The (X,X) and (X,X)* molecules differ in that the (X,X)
molecules are all planar while the (X,X)* molecules are not,
even though they all have gauche con®gurations around the
NÐN bonds. A comparison of benzalazine structures with
ketalazine structures (Chen et al., 1994; Bolte & Ton, 2003;
Lewis et al., 1999) con®rms the fundamentally different
geometry for the two systems. In the benzalazine structures,
including the non-para-substituted parent system, the mol-
ecules are effectively planar with fully conjugated ꢀ systems.
By contrast, in the ketalazine structures, again including the
parent system, the torsion angle about the central CNNC
linkage is large, ranging from 50 to 100ꢀ depending on the para
substitution.
To better understand this difference, we carried out density
functional structure calculations using the M06 density func-
tional (Zhao & Truhlar, 2007) and the MIDI! basis set (Easton
et al., 1996). For the case of 4,40-dichloro substitution, both the
benzalazine and ketalazine systems were subjected to
constrained optimizations where the C NÐN C torsion
angle was varied and held ®xed in increments of 15ꢀ (Fig. 6).
Interestingly, while the ketalazine is predicted to have a
double-well potential characterized by a minimum-energy
geometry with a C NÐN C angle of 105.3ꢀ (in very good
agreement with the experimental value of 103.1ꢀ), the
benzalazine has a triple-well potential, with very shallow
1
of 0ꢀ is predicted to be about 15 kcal mol above the trans
planar minimum.
The relatively ¯at potentials are associated with a balance
between full ꢀ conjugation, available to the planar geometry,
and a push±pull resonance available to the rotated system; the
rotation also minimizes NN lone-pair±lone-pair repulsions
analogous to those in hydrazine, which also adopts a twisted
minimum-energy geometry (Fig. 7). The deeper well for the
twisted geometry of the ketalazine compared with the
benzalazine, relative to the planar structure, is associated with
improved hyperconjugative interactions for the nitrogen lone
pairs delocalizing into the eclipsed ꢀ system when the methyl
groups are present. Thus, natural bond orbital analysis (Reed
et al., 1988) quanti®es the nN ! ꢀ* delocalization for each
nitrogen lone pair as 16.5 kcal mol 1 in the ketalazine system
but only 13.5 kcal mol 1 in the benzalazine system. This is the
largest difference in the ®lled/empty delocalization energies
between the two systems. A consequence of this delocalization
is that the NN bond should be shorter (because of some
double-bond character) in the twisted systems than in the
planar systems, and this is indeed borne out by the experi-
mental structural data (see Table 2).
A second aspect of the packing in the azalazines is the ꢀ
interaction between the benzene rings. The geometric aspects
are given in Table 3, where the perpendicular distances
between the rings and the overlap are given. The overlap is
given as the percentage overlap of the areas in the adjacent C6
rings. The overlap for (I,I-C) is shown in Fig. 8; the molecules
assemble in stacks along the short axis. With two exceptions,
the others are similar; in (I,I-A) there is no overlap, and in
Figure 5
Top: one layer of the structure of (I,Cl), viewed normal to (101). As a
reminder of the disorder, both Cl and I atoms are shown at all positions;
the rest of the disordered positions are not shown. Only the IÁ Á ÁI contacts
are shown. The conventions are the same as in Fig. 4. Bottom: three layers
viewed along b. The middle layer in this view is the layer shown in the top
view.
Figure 6
The energies of the 4,4-dichlorobenzalazine (diamonds, upper line) and
4,4-dichloromethylphenylketalazine (squares, lower line) geometries
relative to the planar structure having a C NÐN C torsion angle of
180ꢀ.
ꢁ
o520 Ojala et al. C14H10I2N2 and C14H10ClIN2
Acta Cryst. (2007). C63, o518±o523

organic compounds
(Br,Cl) and (Br,Br) are isostructural with (I,I-C). (I,Cl) and
(I,Br) are isostructural only with each other. Thus, there are
®ve different structural types in this series of compounds.
When three polymorphs of (I,I) were found, all the remaining
compounds in Table 4 were examined to see if other poly-
morphs could be found. Each compound was recrystallized
from acetone, benzene, dichloromethane, chloroform, tetra-
chloromethane and acetonitrile. Although a variety of crystal
habits were found for each compound, in no case were other
polymorphs found.
Each of the ®ve structure types in Table 4 gives a plausible
packing arrangement for all of the benzalazine compounds, so
this system, which involves only planar molecules, could
provide a reasonable test for programs that predict crystal
packing. It is surprising that in ®ve of the six compounds no
polymorphs were found, even though the search for poly-
morphs was not exhaustive.
Figure 7
Push±pull resonance in the twisted ketalazine geometry.
Experimental
For the preparation of 4-chlorobenzaldehyde hydrazone, a solution of
4-chlorobenzaldehyde (0.5 g, 3.6 mmol) dissolved in approximately
10 ml of ethanol was added dropwise with stirring to an aqueous 8%
hydrazine solution (14.25 g, 3.6 mmol hydrazine). The milky solution
was stirred for approximately 30 min after the completion of the
addition and then cooled in a refrigerator overnight (at 277 K). The
solid hydrazone was removed by ®ltration and used without recrys-
tallization.
For the preparation of 4-chloro-40-iodobenzalazine, 4-chloro-
benzaldehyde hydrazone (0.15 g, 1.0 mmol) was added to a solution
of 4-iodobenzaldehyde (0.2 g, 0.9 mmol) dissolved in 10 ml of abso-
lute ethanol. The mixture was heated to 323 K with stirring for
approximately 1 h, cooled, and then placed in a refrigerator over-
night. The crude azine was recrystallized from chloroform.
For the preparation of 4-iodobenzaldehyde azine, a solution of
4-iodobenzaldehyde (0.1 g, 0.4 mmol) dissolved in approximately
5 ml of ethanol was added dropwise with stirring to an aqueous 8%
Figure 8
The overlap between (I,I-C) molecules (view normal to the molecular
plane). The area of the overlap between the C6 rings is 5.7 (3)% of the
area of either ring.
(I,I-B) the molecules assemble in chains rather than stacks.
(Br,Cl) and (Br,Br) appear to be isostructural with each other,
as do (I,Cl) and (I,Br). These similarities would require
disorder in (Br,Cl) and (I,Br). In view of the disorder in all of
the (X,Y) structures, no data are included here for their ꢀ
overlap. However, they all appear to be similar to that shown
in Fig. 8.
The unit-cell dimensions for all of the (X,X) and (X,Y)
structures are given in Table 4. The (Cl,Cl) structure is unique.
Table 1
a
ꢀ
Ê
Distances and angles (A, ) for the XÁ Á ÁX contacts in (X,X) and (X,X)* .
For comparison, the van der Waals contact distances (Bondi, 1964; Rowland & Taylor, 1996) are ClÁ Á ÁCl =
Ê
Ê
Ê
3.50 A, BrÁ Á ÁBr = 3.70 A and IÁ Á ÁI = 3.96 A.
Compound
Temperature (K)
X
X0
CÐXÁ Á ÁX0
XÁ Á ÁX0
XÁ Á ÁX0ÐC
Reference
(Cl,Cl)
(Cl,Cl)
(Cl,Cl)
(Br,Br)
173
173
294
173
173
294
294
173
173
173
173
294
294
173
Cl1
Cl1
Cl1
Br1
Br1
Br1
Br1
I1
I1
I1
I1
Cl1
Br1
I1
Cl1i
Cl1
Cl1
Br1ii
Br1iii
Br1
Br1
I1iv
I1v
I1vi
I1iii
Cl2
Br2
I10
74.1 (1)
73.8 (1)
74.1 (1)
127.1 (1)
74.2 (1)
126.3 (3)
73.3 (3)
147.0 (2)
109.9 (3)
127.1 (5)
73.2 (5)
163.4 (2)
168.8 (2)
155.3 (3)
3.887 (1)
3.892 (1)
3.958 (1)
3.812 (2)
3.977 (1)
3.861 (4)
4.051 (4)
3.781 (1)
3.965 (2)
3.960 (4)
4.154 (1)
3.340 (1)
3.560 (1)
4.122 (1)
105.9 (1)
105.9 (1)
106.2 (1)
152.6 (1)
105.8 (1)
153.4 (3)
106.7 (3)
147.0 (2)
154.5 (3)
154.9 (5)
106.8 (5)
163.6 (2)
97.0 (2)
b
c
d
b
b
e
e
f
f
f
f
g
g
h
(Br,Br)
(I,I-A)
(I,I-B)
(I,I-C)
(Cl,Cl)*
(Br,Br)*
(I,I)*
101.8 (3)
Notes: (a) the (X,X)* structures are for analogous compounds where the azine H atoms have been replaced by methyl
groups; (b) Ojala et al. (2007a); (c) Glaser et al. (2006); (d) Zheng et al. (2005); (e) Marignan et al. (1972); (f) this work;
1
2
(g) Chen et al. (1994); (h) Lewis et al. (1999). Symmetry codes: (i) x ‡ 1; y; z; (ii) x ‡ 32 ; y
;
z ‡ 32; (iii) x; y 1; z;
1
2
1
(iv) x; y ‡ 1;
z
1; (v) x ‡ 32 ; y
;
z ‡ 12; (vi)
x
1; y
;
2
z ‡ 12.
ꢁ
Acta Cryst. (2007). C63, o518±o523
Ojala et al. C14H10I2N2 and C14H10ClIN2 o521

organic compounds
hydrazine solution (3 g, 8 mmol hydrazine). The milky solution was
heated (lower than 323 K) with stirring for approximately 1 h and was
then allowed to stand at room temperature overnight. The solution
was refrigerated and the crude azine was recrystallized from
chloroform. All three polymorphs were obtained in the original
recrystallization.
Data collection
Bruker SMART 1K CCD area-
detector diffractometer
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003;
Blessing, 1995)
7115 measured re¯ections
1601 independent re¯ections
1290 re¯ections with I > 2ꢄ(I)
Rint = 0.085
Tmin = 0.24, Tmax = 0.84
Re®nement
Polymorph (I,I-A)
R[F2 > 2ꢄ(F2)] = 0.047
wR(F2) = 0.122
S = 1.05
82 parameters
H-atom parameters constrained
Crystal data
3
Ê
Áꢅmax = 3.00 e A
3
Ê
C14H10I2N2
Mr = 460.04
V = 703.5 (2) A
Z = 2
3
Ê
1.34 e A
1601 re¯ections
Áꢅmin
=
Monoclinic, P21=c
Mo Kꢂ radiation
ꢃ = 4.45 mm
T = 174 (2) K
0.45 Â 0.35 Â 0.06 mm
1
Ê
a = 11.854 (2) A
Compound (I,Cl)
Ê
b = 7.7308 (13) A
Ê
c = 7.6827 (13) A
Crystal data
ꢁ = 92.407 (3)ꢀ
3
Ê
C14H10ClIN2
Mr = 368.59
Monoclinic, Pc
V = 676.9 (2) A
Z = 2
Data collection
Mo Kꢂ radiation
Bruker SMART 1K CCD area-
detector diffractometer
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003;
Blessing, 1995)
7773 measured re¯ections
1602 independent re¯ections
1442 re¯ections with I > 2ꢄ(I)
Rint = 0.031
1
Ê
Ê
a = 11.499 (2) A
ꢃ = 2.55 mm
T = 174 (2) K
b = 4.0006 (7) A
Ê
c = 14.717 (3) A
0.20 Â 0.20 Â 0.05 mm
ꢁ = 90.900 (3)ꢀ
Tmin = 0.32, Tmax = 0.77
Data collection
Re®nement
Bruker SMART 1K CCD area-
detector diffractometer
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003;
Blessing, 1995)
7262 measured re¯ections
3089 independent re¯ections
2308 re¯ections with I > 2ꢄ(I)
Rint = 0.032
R[F2 > 2ꢄ(F2)] = 0.022
wR(F2) = 0.054
S = 1.11
83 parameters
H-atom parameters constrained
3
Ê
Áꢅmax = 0.86 e A
3
Ê
0.55 e A
1602 re¯ections
Áꢅmin
=
Tmin = 0.42, Tmax = 0.88
Re®nement
R[F2 > 2ꢄ(F2)] = 0.038
wR(F2) = 0.072
S = 1.05
3089 re¯ections
164 parameters
109 restraints
H-atom parameters constrained
3
Polymorph (I,I-B)
Ê
Áꢅmax = 0.50 e A
3
Ê
0.33 e A
Áꢅmin
=
Crystal data
Absolute structure: Flack (1983),
1476 Friedel pairs
Flack parameter: 0.17 (7)
3
Ê
C14H10I2N2
Mr = 460.04
V = 703.0 (3) A
Z = 2
Monoclinic, P21=n
Mo Kꢂ radiation
1
Ê
a = 8.4303 (17) A
ꢃ = 4.46 mm
T = 174 (2) K
Ê
b = 5.6453 (12) A
Table 2
Comparison of NÐN distances (A) between (X,X) and (X,X)*.
Ê
Ê
c = 15.248 (3) A
0.30 Â 0.06 Â 0.03 mm
ꢁ = 104.346 (3)ꢀ
X
(X,X)
Reference
(X,X)*
Reference
Data collection
H
Cl
1.418 (3)
1.412 (10)
1.412 (2)
1.414 (3)
1.409 (2)
1.45 (2)
1.411 (4)
1.411 (4)
1.418 (6)
1.400 (12)
a
c
e
f
g
h
g
i
1.403 (3)
1.396 (2)
1.398 (3)
±
±
1.383 (6)
±
1.396 (6)
b
d
b
±
±
b
±
j
Bruker SMART 1K CCD area-
detector diffractometer
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003;
Blessing, 1995)
7699 measured re¯ections
1600 independent re¯ections
1189 re¯ections with I > 2ꢄ(I)
Rint = 0.052
Br
I
Tmin = 0.54, Tmax = 0.87
Re®nement
i
i
±
±
±
±
R[F2 > 2ꢄ(F2)] = 0.031
wR(F2) = 0.061
S = 1.02
83 parameters
H-atom parameters constrained
Notes: (a) Mom & de With (1978); (b) Chen et al. (1994); (c) Burke-Laing & Laing
(1976); (d) Bolte & Ton (2003); (e) Glaser et al. (2006); (f) Zheng et al. (2005); (g) Ojala
et al. (2007a); (h) Marignan et al. (1972); this work; (j) Lewis et al. (1999).
3
Ê
Áꢅmax = 0.48 e A
3
Ê
0.61 e A
1600 re¯ections
Áꢅmin
=
Table 3
Ê
Polymorph (I,I-C)
The inter-ring distances (A) and ring overlaps (%) of the ꢀ contacts.
Crystal data
Ê
Distance (A)
Compound
Overlap (%)
Reference
3
Ê
C14H10I2N2
Mr = 460.04
V = 698.2 (3) A
Z = 2
(Cl,Cl)
(Br,Br)
(I,I-A)
(I,I-B)
(I,I-C)
3.459 (4)
3.479 (6)
No overlap
3.584 (8)
3.522 (3)
17.8 (2)
12.8 (2)
a
a
b
b
b
Monoclinic, P21=c
Mo Kꢂ radiation
ꢃ = 4.49 mm
T = 174 (2) K
0.45 Â 0.10 Â 0.04 mm
1
Ê
a = 7.2077 (17) A
12.7 (2)
5.7 (2)
Ê
b = 4.1543 (10) A
Ê
c = 23.317 (6) A
ꢁ = 90.314 (4)ꢀ
Notes: (a) Ojala et al. (2007a); (b) this work.
ꢁ
o522 Ojala et al. C14H10I2N2 and C14H10ClIN2
Acta Cryst. (2007). C63, o518±o523

organic compounds
Table 4
Cell constants (A, , A ) for all (X,X) and (X,Y) structures at 173 K.
3
ꢀ
Ê
Ê
Compound
a
b
c
ꢁ
V
Reference
(Cl,Cl)
(Br,Cl)
(Br,Br)
(I,Cl)
3.887 (1) 6.990 (1) 22.980 (2)
6.995 (1) 3.945 (1) 22.971 (4)
7.027 (1) 3.977 (1) 23.141 (3)
11.499 (2) 4.001 (1) 14.717 (3)
11.513 (5) 4.044 (2) 14.719 (4)
90.77 (1) 624.3 (1)
92.72 (1) 633.1 (2)
91.72 (1) 646.5 (1)
90.90 (1) 676.9 (2)
90.34 (2) 685.3 (3)
92.41 (1) 703.5 (2)
a
b
a
c
b
c
c
c
(I,Br)
(I,I-A)
(I,I-B)
(I,I-C)
11.854 (2) 7.731 (1)
7.683 (1)
8.430 (2) 5.645 (1) 15.248 (3) 104.35 (1) 703.0 (3)
7.208 (2) 4.154 (1) 23.317 (6) 90.31 (1) 698.2 (3)
Notes: (a) Ojala et al. (2007a); (b) Ojala et al. (2007b); (c) this work.
Bolte, M. & Ton, Q. C. (2003). Private communication (deposition number
223135). CCDC, Union Road, Cambridge, England.
Bondi, A. (1964). J. Phys. Chem. 68, 441±451.
Bruker (2003). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin,
USA.
Burke-Laing, M. & Laing, M. (1976). Acta Cryst. B32, 3216±3224.
Chen, S. C., Anthamatten, M., Barnes, C. L. & Glaser, R. (1994). J. Org. Chem.
59, 4336±4340.
Desiraju, G. R. (1987). Organic Solid State Chemistry, edited by G. R. Desiraju,
pp. 519±546. Amsterdam: Elsevier.
The solutions and re®nements were straightforward except for
(I,Cl). This structure was solved as an end-for-end disordered mol-
ecule in P21/c; the re®nement converged with R[F2 > 2ꢄ(F2)] = 0.043
and wR(F2) = 0.084. To test whether the disorder was complete, the
structure was solved and partially re®ned in P1. At this point, it
appeared that the disorder was not 50/50 and that Pc was the correct
space group; the ®nal R and wR2 values were 0.038 and 0.072, with
0.586 (2)/0.414 (2) disorder of the Cl and I atoms. In all of the
Ê
re®nements, CÐCl distances were constrained to 1.746 (1) A and
Ê
CÐI to 2.095 (1) A; all of the C6H4ÐCHÐN fragments were
Desiraju, G. R. (1989). Crystal Engineering, pp. 75±76, 171±193. Amsterdam:
Elsevier.
Desiraju, G. R. (1995). Angew. Chem. Int. Ed. Engl. 34, 2311±2327.
Easton, R. E., Giesen, D. J., Welch, A., Cramer, C. J. & Truhlar, D. G. (1996).
Theor. Chim. Acta, 93, 281±301.
Flack, H. D. (1983). Acta Cryst. A39, 876±881.
Glaser, R., Murphy, R. F., Sui, Y., Barmes, C. L. & Kim, S. H. (2006).
CrystEngComm, 8, 372±374.
Ê
constrained to be the same within 0.001 A. The atoms that would
have overlapped in the pseudo-centric arrangement were constrained
to have the same anisotropic displacement parameters. H atoms were
placed at geometrically idealized positions and constrained to ride on
Ê
their parent atoms, with CÐH distances of 0.95 A and Uiso(H) values
of 1.2Ueq(C).
Lewis, M., Barnes, C. L. & Glaser, R. (1999). J. Chem. Crystallogr. 29, 1043±
1048.
For all determinations, data collection: SMART (Bruker, 2003);
cell re®nement: SAINT (Bruker, 2003); data reduction: SAINT;
program(s) used to solve structure: SHELXTL (Sheldrick, 1997);
program(s) used to re®ne structure: SHELXTL; molecular graphics:
SHELXTL; software used to prepare material for publication:
SHELXTL.
Â
Marignan, J., Galigne, J. L. & Falgueirettes, J. (1972). Acta Cryst. B28, 93±97.
Mom, V. & de With, G. (1978). Acta Cryst. B34, 2785±2789.
Ojala, C. R., Ojala, W. H. & Britton, D. (2007a). Private communication
(deposition numbers 641726 and CCDC 642092). CCDC, Union Road,
Cambridge, England.
Ojala, C. R., Ojala, W. H. & Britton, D. (2007b). Unpublished work.
Reed, A. E., Curtiss, L. A. & Weinhold, F. (1988). Chem. Rev. 88, 899±926.
Rowland, R. S. & Taylor, R. (1996). J. Phys. Chem. 100, 7384±7391.
Sakurai, T., Sundaralingam, M. & Jeffrey, G. A. (1963). Acta Cryst. 16, 354±
363.
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: GA3056). Services for accessing these data are
described at the back of the journal.
Schmidt, G. M. J. (1971). Pure Appl. Chem. 27, 647±678.
Sheldrick, G. M. (1997). SHELXTL. Version 5.0. Siemens Analytical X-ray
Instruments Inc., Madison, Wisconsin, USA.
È
Sheldrick, G. M. (2003). SADABS. Version 2.10. University of Gottingen,
Germany.
Zhao, Y. & Truhlar, D. G. (2007). Theor. Chim Acta. In the press.
Zheng, P.-W., Wang, W. & Duan, X.-M. (2005). Acta Cryst. E61, o3020±o3021.
References
Blessing, R. H. (1995). Acta Cryst. A51, 33±38.
ꢁ
Acta Cryst. (2007). C63, o518±o523
Ojala et al. C14H10I2N2 and C14H10ClIN2 o523