Role of Hetero-halogen (F · · · X, X = Cl, Br, and I) or homo-halogen (X · · · X, X = F, Cl, Br, and I) interactions in substituted benzanilides

Article abstract of DOI:10.1021/cg101544z

A series of halogen-substituted benzanilides have been synthesized and characterized, and crystallization studies directed toward generation of polymorphs have been performed to delineate the importance of interactions involving halogens. The effect of ha

Full text of DOI:10.1021/cg101544z

ARTICLE
pubs.acs.org/crystal
Role of Hetero-Halogen (F X, X = Cl, Br, and I) or Homo-Halogen
3 3 3
(X X, X = F, Cl, Br, and I) Interactions in Substituted Benzanilides
Published as part of a virtual special issue on Structural Chemistry in India: Emerging Themes.
3 3 3
Susanta K. Nayak,† M. Kishore Reddy,† Tayur N. Guru Row,*,† and Deepak Chopra*,‡
†Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, Karnataka, India
‡Department of Chemistry, Indian Institute of Science Education and Research, ITI (Gas Rahat Building), Govindpura, Bhopal 462023
S Supporting Information
b
ABSTRACT: A series of halogen-substituted benzanilides have
been synthesized and characterized, and crystallization studies
directed toward generation of polymorphs have been performed
to delineate the importance of interactions involving halogens. The
effect of halogen substitution on the molecular conformation and
supramolecular packing has been investigated. The N-H
O
3 3 3
H-bond is a key structure-directing element acting in conjunction
with C-H O and C-H π interactions. In addition, it is of
3 3 3 3 3 3
importance to note that organic fluorine prefers Type I F
contacts, whereas Cl, Br, and I prefer Type II contacts. Hetero-
F
3 3 3
halogen halogen interactions on the other hand are predomi-
3 3 3
nately of Type II geometry, and this is due to the greater
polarizability of the electron density associated with the heavier
halogens. It is of importance to evaluate the contributing role of
these interactions in crystal structure packing and the co-oper-
ativity associated with such interactions in the solid state.
’ INTRODUCTION
CCR5 receptor ligands, anti-inflammatory, antiviral agents, and in the
application of voltage-dependent potassium channel operators.8 This
molecular system allows one to explore the regime of strong N-
Halogenated compounds, in particular, fluorinated molecules,
have received considerable attention in chemistry and biology.1
Introduction of fluorine (15% of all pharmaceuticals include at
least one fluorine atom2) into biologically active compounds
results in improved pharmacological properties. The physical and
chemical properties of compounds are altered by replacing the
hydrogen atoms with fluorine, due to its high electronegativity,
low polarizability, and bond strength.3 Though the role of
fluorine involved interactions (C-H F, F F, C-F π)
H
O hydrogen bonds (presence of amino and carbonyl group),
3 3 3
weak C-H O hydrogen bonds (activated C-H), weak N-
3 3 3
H
F (intra)/C-H F/F F (presence of organic fluorine
3 3 3
3 3 3 3 3 3
on either or both aromatic rings), and finally the weakest of
all intermolecular interactions, which includes C-H π and π
π
3 3 3
3 3 3
interactions. Subtle differences in the energetics associated with weak
and flexible C-H F interactions have resulted in the formation of
3 3 3
3 3 3
3 3 3
3 3 3
polymorphs9 and in situ cryocrystallization of liquids.10 Topological
are considered weak, it plays a vital role in directing the molecular
assembly which has been highlighted by H€ulliger and co-workers
and several other research groups.4 The importance of C-
characterization of weak C-H F and C-F F-C contacts
3 3 3 3 3 3
using high resolution charge density data have also been performed.11
The significance of intramolecular N-H F hydrogen bonds has been
3 3 3
utilized for the construction of folding architectures in aromatic amides.12
H
F interactions in the absence of strong hydrogen bonds
3 3 3
has been well established.5 The evaluation of weak interactions in
the presence of strong hydrogen bonds has generated widespread
interest among the crystal engineering community, particularly with
the design and application of these compounds in the area of
polymorphism. Recent efforts have been directed toward the
understanding of intra- and intermolecular interactions involving
“ordered” and “disordered” organic fluorine in tetrahydroindoles
and mono- and di-fluorinated benzanilides.6
Again the preference of an intramolecular six-/five-membered N-
H
X (X = Cl, Br, and I) hydrogen bonding pattern in the absence
3 3 3
or presence of intermolecular N-H O hydrogen bonds has been
3 3 3
highlighted in halogenated aromatic amides.13,14
In view of the above-mentioned interests, it was of interest to
explore the nature of intermolecular interactions in halogenated
benzanilides, containing bromine, chlorine, and iodine in the
Benzanilides are present in a wide range of biological
compounds and serve as intermediates for many pharmaceutical
compounds.7 Differently substituted benzanilides have been used as
Received: November 21, 2010
Revised:
January 16, 2011
Published: March 14, 2011
r
2011 American Chemical Society
1578
dx.doi.org/10.1021/cg101544z Cryst. Growth Des. 2011, 11, 1578–1596
|

Crystal Growth & Design
ARTICLE
Scheme 1. Geometrical Classification of Halogen Halo-
3 3 3
gen Interaction as Type I and Type II
Figure 1. Synthetic procedure of dihalogenated benzanilides (all com-
bination of mixed halogen keeping fluorine in one side of the ring):
When X = F [ortho (2), meta (3), para (4)]; Y = Cl or Br or I [ortho (2),
meta (3), para (4)]; Y = F [ortho (2), meta (3), para (4)].
presence of organic fluorine and to illustrate the changes in
supramolecular assembly [the importance of homo (symmetric)
X
X (F, Cl, Br, and I), X Y (F, Cl, Br, and I), hetero
3 3 3
3 3 3
(unsymmetrical) halogen, and C-X π (F, Cl, Br, and I)
3 3 3
interactions] which govern crystal formation.15,16 The evaluation
of homo (symmetric) interactions has been performed on a series
of benzanilides, containing the halogen chlorine on either or both
of the aromatic phenyl rings.17 Such halogen-halogen interac-
tions have been termed as Type I (cis and trans geometry) and
Type II (electrophile-nucleophile model) depending on the
angular approach of the halogens toward each other
(Scheme 1). These have been coined “attractive” in an investiga-
Figure 2. Representation of the nomenclature used in this chapter.
Circles are drawn to identify the two sides: Aniline side (A) and benzoyl
side (B). (For example: 2FA-2ClB represents the compound in Group 1;
Set 1.)
(CdO)νmax = 1650 cm-1 provides the evidence for the product
formation. Further, the purity of sample was characterized by melting
point, NMR, and powder X-ray data. Single crystals of desired size and
quality were grown by slow evaporation at 0 and 25 ꢀC by dissolving the
substance in different solvent combinations such as (ethyl acetate/
hexane) and (dichloromethane/hexane). Morphologies ranging from
thin plates to fibrous needles were obtained.
tion performed on CH3/H-F Cl-CF3 dimers via a decom-
3 3 3
position of the interaction energy. The presence of a
trifluoromethyl group linked to chlorine leads to an enhanced
polarization of the C-Cl bond resulting in an increased strength
of the Cl F contact.18 Recently, the application of Voronoi-
3 3 3
Dirichlet polyhedrals (VDPs) has been demonstrated to analyze
intermolecular interactions in crystal structures of halogens or
interhalogen compounds to understand structure-property cor-
relations in this class of molecules.19
Single Crystal Data Collection and Refinement. Single
crystal X-ray diffraction data of some of these compounds were collected
on a Bruker AXS SMART APEX CCD diffractometer with X-ray
generator operating at 50 kV and 35 mA using graphite monochromated
MoKR (λ = 0.7107 Å)22 radiation. The data for rest of the compounds
were recollected on CrysAlis CCD Xcalibur, Eos (Nova), Oxford
Diffraction with X-ray generator operating at 50 kV and 1 mA, using
MoKR radiation (λ = 0.7107 Å).23 Data were collected for 606 frames
per set by using SMART with different settings of j (0ꢀ, 90ꢀ, 180ꢀ)
keeping a sample to detector distance of 6.062 cm and the 2θ value fixed
at -25ꢀ. Data reduction and analysis were performed by SAINTPLUS,
XPREP, and SADABS.24 The structures were solved and refined by using
SHELXL97,24 using the program suite WinGX.25 The molecular dia-
grams were generated using ORTEP-3,26 and the packing diagrams were
generated using Mercury.27 The geometric calculations were carried out
by PARST9528 and PLATON.29 The non-hydrogen atoms are refined
anisotropically and the hydrogen atoms bonded to C and N atoms were
positioned geometrically and refined using a riding model with distance
restraints of N-H = 0.86 Å, aromatic C-H = 0.93 Å and with Uiso(H)
=1.2Ueq(N,C). Tables 2, 5, 8, 11, 13 and 16. lists all crystallographic
details. Intra- and intermolecular interactions are listed in
We present here the importance of fluorine in the presence of
other halogen (Cl, Br, or I) atoms in dihalogenated benzanilide
compounds to evaluate the preference of hetero-halogen F
X
3 3 3
(Cl, Br, and I) over homo-halogen X X (F, Cl, Br, and I)
3 3 3
interactions along with other weak (C-H F/Cl/Br, C-
3 3 3
X
π) and strong (N-H O) hydrogen bonds. In this
3 3 3
3 3 3
context, we have synthesized several possible combinations of
such compounds having a single fluorine atom on one of the
aromatic rings while the other ring has a different halogen (Cl, Br,
or I) substitution (Figure 1).
It is important to describe the nomenclature used in this article
at this stage since a large number of compounds have been
studied. In this context, Table 1 gives the details of abbreviations
used for naming the compounds as shown in Figure 2.
’ EXPERIMENTAL SECTION
Synthesis and Crystallization. The dihalogenated benzanilides
were prepared by the reaction of mono halogen substituted aniline
(ortho, meta, para) (2.626 mmol) and 4-diaminomethylaminopyridine
(2.626 mmol) in dry dichloromethane in a nitrogen atmosphere as
mentioned in Figure 1.21 Respectively, a mono halogenated benzoyl
chloride (ortho, meta, para) (2.626 mmol) was added dropwise with
stirring at room temperature. The mixture was stirred for 12 h at room
temperature. The reaction progress was monitored by thin layer
chromatography. The solvent was removed in vacuo and solid was
extracted with DCM solvent. The infrared (IR) value for amide
Tables 3, 6, 9, 12, 14 and 17. whereas halogen halogen interactions
are listed in Tables 4, 7, 10, 15 and 18. ORTEP plots and dihedral angles
are included in Supporting Information (Figure S1 and Table S1).
3 3 3
’ RESULTS
Group A (Set I). 2FA-2ClB crystallizes in the centrosym-
metric monoclinic space group P21/n with Z = 4 (Figure 3a,
Table 2). It is noteworthy that all the crystal structures discussed
1579
dx.doi.org/10.1021/cg101544z |Cryst. Growth Des. 2011, 11, 1578–1596

Crystal Growth & Design
ARTICLE
Table 1. Description of Abbreviations Used for the Compounds Studied in this Section
fluorine on the aniline side (A) IUPAC nomenclature
remark
Group A
Set I
2FA-2ClB
2FA-2BrB
2FA-2IB
2-chloro-N-(2-fluorophenyl)benzamide
2-bromo-N-(2-fluorophenyl)benzamide
2-iodo-N-(2-fluorophenyl)benzamide
3-chloro-N-(2-fluorophenyl)benzamide
3-bromo-N-(2-fluorophenyl)benzamide
3-iodo-N-(2-fluorophenyl)benzamide
4-chloro-N-(2-fluorophenyl)benzamide
4-bromo-N-(2-fluorophenyl)benzamide
4-iodo-N-(2-fluorophenyl)benzamide
quality crystals not obtaineda
Set II
Set III
2FA-3ClB
2FA-3BrB
2FA-3IB
b
quality crystals not obtaineda
2FA-4ClB
2FA-4BrB
2FA-4IB
Group B
Set I
3FA-2ClB
3FA-2BrB
3FA-2IB
2-chloro-N-(3-fluorophenyl)benzamide
2-bromo-N-(3-fluorophenyl)benzamide
2-iodo-N-(3-fluorophenyl)benzamide
3-chloro-N-(3-fluorophenyl)benzamide
3-bromo-N-(3-fluorophenyl)benzamide
3-iodo-N-(3-fluorophenyl)benzamide
4-chloro-N-(3-fluorophenyl)benzamide
4-bromo-N-(3-fluorophenyl)benzamide
4-iodo-N-(3-fluorophenyl)benzamide
disorder
disorder
disorder
quality crystals not obtaineda
Set II
Set III
3FA-3ClB
3FA-3BrB
3FA-3IB
disorder
quality crystals not obtaineda
3FA-4ClB
3FA-4BrB
3FA-4IB
quality crystals not obtaineda
quality crystals not obtaineda
Group C
Set I
4FA-2ClB
4FA-2BrB
4FA-2IB
2-chloro-N-(4-fluorophenyl)benzamide
2-bromo-N-(4-fluorophenyl)benzamide
2-iodo-N-(4-fluorophenyl)benzamide
3-chloro-N-(4-fluorophenyl)benzamide
3-bromo-N-(4-fluorophenyl)benzamide
3-iodo-N-(4-fluorophenyl)benzamide
4-chloro-N-(4-fluorophenyl)benzamide
4-bromo-N-(4-fluorophenyl)benzamide
4-iodo-N-(4-fluorophenyl)benzamide
Set II
Set III
4FA-3ClB
4FA-3BrB
4FA-3IB
quality crystals not obtaineda
quality crystals not obtaineda
4FA-4ClB
4FA-4BrB
4FA-4IB
quality crystals not obtaineda
fluorine on the benzoyl side (B) IUPAC nomenclature
Group D
Set I
2FB-2ClA
2FB-2BrA
2FB-2IA
2-fluoro-N-(2-chlorophenyl)benzamide
2-fluoro-N-(2-bromophenyl)benzamide
2-fluoro-N-(2-iodophenyl)benzamide
2-fluoro-N-(3-chlorophenyl)benzamide
2-fluoro-N-(3-bromophenyl)benzamide
2-fluoro-N-(3-iodophenyl)benzamide
2-fluoro-N-(4-chlorophenyl)benzamide
2-fluoro-N-(4-bromophenyl)benzamide
2-fluoro-N-(4-iodophenyl)benzamide
disorder
disorder
disorder
Set II
Set III
2FB-3ClA
2FB-3BrA
2FB-3IA
quality crystals not obtaineda
quality crystals not obtaineda
2FB-4ClA
2FB-4BrA
2FB-4IA
quality crystals not obtaineda
Group E
Set I
3FB-2ClA
3FB-2BrA
3FB-2IA
3-fluoro-N-(2-chlorophenyl)benzamide
3-fluoro-N-(2-bromophenyl)benzamide
3-fluoro-N-(2-iodophenyl)benzamide
3-fluoro-N-(3-chlorophenyl)benzamide
3-fluoro-N-(3-bromophenyl)benzamide
3-fluoro-N-(3-iodophenyl)benzamide
3-fluoro-N-(4-chlorophenyl)benzamide
3-fluoro-N-(4-bromophenyl)benzamide
quality crystals not obtaineda
Set II
Set III
3FB-3ClA
3FB-3BrA
3FB-3IA
quality crystals not obtaineda
disorder
3FB-4ClA
3FB-4BrA
disorder
1580
dx.doi.org/10.1021/cg101544z |Cryst. Growth Des. 2011, 11, 1578–1596

Crystal Growth & Design
ARTICLE
Table 1. Continued
fluorine on the benzoyl side (B) IUPAC nomenclature
3-fluoro-N-(4-iodophenyl)benzamide
3FB-4IA
quality crystals not obtaineda
Group F
Set I
4FB-2ClA
4FB-2BrA
4FB-2IA
4-fluoro-N-(2-chlorophenyl)benzamide
4-fluoro-N-(2-bromophenyl)benzamide
4-fluoro-N-(2-iodophenyl)benzamide
4-fluoro-N-(3-chlorophenyl)benzamide
4-fluoro-N-(3-bromophenyl)benzamide
4-fluoro-N-(3-iodophenyl)benzamide
4-fluoro-N-(4-chlorophenyl)benzamide
4-fluoro-N-(4-bromophenyl)benzamide
4-fluoro-N-(4-iodophenyl)benzamide
Set II
Set III
4FB-3ClA
4FB-3BrA
4FB-3IA
4FB-4ClA
4FB-4BrA
4FB-4IA
quality crystals not obtaineda
a Crystals were obtained for such compounds. However, these are not suitable enough for single crystal XRD. Crystallization experiments are still currently
underway which are directed toward obtaining quality crystals for crystal structure determination. b This structure exhibits polymorphic behavior and disorder
structures are reported in a private communication.20 However, it may be mentioned that one of the polymorphs is isostructural to 2FA-3BrB.
Table 2. Crystallographic Information
Set (I)
Set (II)
2FA-3BrB
Set (III)
2FA-2ClB
2FA-2BrB
2FA-3ClBa
2FA-4ClB
2FA-4BrB
2FA-4IB
formula
C
13H9NOFCl
C13H9NOFBr
294.1
C13H9NOFCl
249.7
C13H9NOFBr
294.1
C13H9NOFCl
249.7
C13H9NOFBr
294.1
C13H9NOFI
341.1
formula weight
temperature K
size of crystal (mm)
249.7
292(2)
0.30 ꢀ 0.28
ꢀ 0.21
774783
P21/n
292(2)
0.34 ꢀ 0.22
ꢀ 0.12
765329
Pna21
292(2)
0.24 ꢀ 0.22
ꢀ 0.15
751294
P21/c
292(2)
0.27 ꢀ 0.05
ꢀ 0.04
765330
P21/c
292(2)
0.28 ꢀ 0.21
ꢀ 0.19
774786
P21
292(2)
0.30 ꢀ 0.23
ꢀ 0.15
765331
P21
292(2)
0.23 ꢀ 0.16
ꢀ 0.14
774780
P21
CCDC no.
space group
a (Å)
4.912 (1)
5.858(2)
39.459(5)
90
12.410(2)
11.071(2)
8.605(1)
90
23.905(5)
4.996(1)
19.392(4)
90
23.935(2)
4.966(1)
19.884(2)
90
4.918(5)
5.597(5)
20.553(5)
90
4.919(1)
5.616(1)
21.009(5)
90
4.919(3)
5.577(3)
21.819(1)
90
b (Å)
c (Å)
R (ꢀ)
β (ꢀ)
γ (ꢀ)
volume (Å3)
90.362(2)
90
90
101.290(4)
90
102.297(2)
90
90.128(5)
90
90.115(28)
90
91.038(6)
90
90
1135.4(1)
4
1182.3(1)
4
2271.0(2)
8
2309.4(1)
8
565.7(5)
2
580.4(2)
2
598.5(2)
2
Z
density (g cm-3
)
1.46
1.65
1.46
1.69
1.47
1.68
1.89
μ (mm-1
)
0.330
3.471
0.330
3.554
0.331
3.535
2.670
F (000)
511.9
583.9
1023.9
1167.8
256.0
292.0
328
θmin, max (ꢀ)
hmin, max
2.1, 26.0
-6, 6
2.5, 28.0
-16, 15
-14, 13
-11, 11
9784
1.7, 25.0
-28, 28
-5, 5
1.7, 26.0
-29, 29
-5, 6
3.8, 26.0
-6, 6
1.9, 26.0
-6, 6
2.8, 26.0
-6, 6
kmin, max
-7, 6
-6, 6
-6, 6
-6, 6
lmin, max
-48, 48
8265
-23, 23
20215
-24, 22
16710
-25, 25
6357
-25, 24
4434
-26, 26
6486
no. of reflections measured
no. unique reflections
no. of parameter
2229
2797
3983
4508
1337
2226
2324
154
158
307
307
154
154
155
R_all, R_obs
0.100, 0.073
0.146, 0.139
0.292, -0.252
1.158
0.052, 0.035
0.083, 0.077
0.532, -0.477
1.011
0.177, 0.064
0.109, 0.089
0.213, -0.187
0.898
0.093, 0.044
0.085, 0.077
0.458, -0.272
0.941
0.072, 0.036
0.075, 0.066
0.121, -0.138
0.832
0.060, 0.039
0.081, 0.075
0.655, -0.188
1.004
0.077, 0.073
0.205, 0.203
2.350, -1.705
1.141
wR2_all, wR2_obs
ΔFmax, min (e Å-3
)
GOF
a Exhibit polymorphism.20
in this chapter exhibit the N-H O hydrogen bond chains as a
shown in Figure 3c (Table 3). 2FA-2BrB is not isostructural and
crystallizes in noncentrosymmetric orthorhombic space group
3 3 3
common feature (Figure 3b). In addition, a dimeric motif
involving C-H F and C-H Cl provides stability to the
Pna21 (Z = 4). An intramolecular C-H O bond stabilizes the
3 3 3 3 3 3
3 3 3
crystal packing by forming a two-dimensional (2-D) network as
conformation of the molecule (Figure 4a). In addition to
1581
dx.doi.org/10.1021/cg101544z |Cryst. Growth Des. 2011, 11, 1578–1596

Crystal Growth & Design
ARTICLE
Table 3. Intra- and Intermolecular Interactionsa
D-H
A
D
H/Å
D
A/Å
H
A/Å
—D-H A/ꢀ
symmetry
3 3 3
3 3 3
3 3 3
3 3 3
3 3 3
2FA-2ClB
2FA-2BrB
2FA-3BrB
N1-H1 O1
0.86
0.93
0.93
0.93
0.93
2.869(3)
3.587(5)
3.437(5)
3.642(4)
2.907(4)
2.945(3)
3.438(5)
3.776(4)
2.919(4)
2.934(4)
2.927(4)
2.894(4)
3.257(4)
3.380(4)
3.753(4)
2.907(5)
2.937(4)
3.414(5)
3.454(4)
2.899(4)
2.942(3)
3.414(4)
3.470(5)
2.95(2)
2.02
2.67
2.70
2.97
2.42
2.27
2.52
3.03
2.46
2.48
2.12
2.09
2.50
2.46
2.98
2.45
2.13
2.50
2.59
2.44
2.14
2.50
2.63
2.48
2.11
2.49
2.69
168
168
136
130
113
169
170
137
111
110
156
155
139
173
148
110
156
169
154
111
155
169
153
111
155
166
151
1 þ x, y, z
x - 1,þy - 1, þz
3 3 3
C12-H12 F1
3 3 3
C10-H10 F1
-x þ 1/2 þ 2, y - 1/2, -z þ 1/2
x - 1, y - 1, z
x, y, z
3 3 3
C3-H3 Cl1
3 3 3
C13-H13 O1
3 3 3
N1-H1 O1
0.68(3)
0.93
0.93
0.93
0.93
0.86
0.86
0.93
0.93
0.93
0.93
0.86
0.93
0.93
0.93
0.86
0.93
0.93
0.93
0.86
0.93
0.93
-x, 1 - y, -1/2 þ z
1/2 - x, -1/2 þ y, -1/2 þ z
x þ 1/2 þ 2, -y þ 1/2, z
x, y, z
3 3 3
C10-H10 O1
3 3 3
C4-H4 Br1
3 3 3
C13-H13 O1
3 3 3
C130H130
O10
x, y, z
3 3 3
N1-H1 O1
x, -1 þ y, z
3 3 3
N10-H10
O10
x, 1 þ y, z
3 3 3
C2-H2 F10
x, -1 þ y, z
3 3 3
C100-H100
F1
x, 1 þ y, z
3 3 3
C13-H13 Cg4
x, y, z
3 3 3
2FA-4ClB
2FA-4BrB
2FA-4IB
C13-H13 O2
x, y, z
3 3 3
N1-H1 O2
-1 þ x, y, z
1 þ x, 1 þ y, z
1 þ x, -1 þ y, z
x, y, z
3 3 3
C12-H12 F1
3 3 3
C3-H3 O1
3 3 3
C13-H13 O1
3 3 3
N1-H1 O1
1 þ x, y, z
-1 þ x, 1 þ y, z
x - 1, y - 1, z
x, y, z
3 3 3
C12-H12 F1
3 3 3
C3-H3 O1
3 3 3
C13-H13 O1
3 3 3
N1-H1 O1
2.915(13)
3.400(18)
3.540(3)
-1 þ x, y, z
1 þ x, 1 þ y, z
x þ 1, y - 1, z
3 3 3
C12-H12 F1
3 3 3
C3-H3 O1
3 3 3
a Cg4 = centroid of C50-C130 atom.
Table 4. Halogen
Halogen Short Contact
3 3 3 3
C-X Y-C
3 3 3
X
Y/Å
—C-X Y/ꢀ
—C-Y X/ꢀ
3 3 3
symmetry
type
3 3 3
3 3 3
2FA-3BrB
2FA-4ClB
2FA-4BrB
2FA-4IB
C5-Br1 Br10-C50
3.721(3)
3.548(1)
3.656(2)
3.873(1)
172
171
172
93
110
92
-x, -y þ 2, -z þ 1
II
II
II
II
3 3
C4-Cl1 Cl1-C4
-x þ 1, þy - 1/2, -z þ 1
-x, þy - 1/2, -z þ 1
-x þ 1, y - 1/2, -z þ 1
3 3 3
C4-Br1 Br1-C4
86
3 3 3
C4-I1 I1-C4
174
3 3 3
N-H O intermolecular hydrogen bond, C-H O and C-
3 3 3 3 3 3
details of the polarizability versus size factor in halogen-
H
Br contacts result in the formation a “wavelike” packing
halogen interaction (Table 4).
3 3 3
3 3 3
feature along the a-axis (Figure 4b and Table 3).
Group A (Set III). 2FA-4ClB, 2FA-4BrB, and 2FA-4IB are
isostructural with noncentrosymmetric monoclinic P21 space
group with Z = 2 (Table 2). All the three structures show the
Group A (Set II). 2FA-3ClB and 2FA-3BrB are isostructural
and crystallize in a monoclinic space group P21/c with Z = 8
(Z0 = 2) (Table 2). Indeed, 2FA-3ClB exhibits polymorphism.20
intramolecular C-H O interaction involving H13 which lock
3 3 3
Intramolecular C-H O (involving H13) interaction stabi-
3 3 3
the molecular conformation. N-H O hydrogen bonds form
3 3 3
lizes the molecular conformation. In addition to the strong N-
chains along the a-axis which are further stabilized by additional
H
O hydrogen bond, the two independent molecules are held
3 3 3
C-H O (involving H3) and C-H F (involving H12)
3 3 3 3 3 3
together by a C-H π interaction (Table 3). This also
3 3 3
weak interactions (Table 3). The C-H O and C-H
3 3 3
F
3 3 3
induces the formation of a C-H F dimer motif across the
3 3 3
interactions form a dimer motif arrangement. Homo-halogen
crystallographic 2-fold symmetry (Figure 5). It is interesting
X
X (Cl, Br, and I) interactions of Type II [θ1 = 172, θ2 =
to note that while a Type I, Cl Cl short contact [3.33 Å, θ1
3 3 3
3 3 3
86-110ꢀ] are preferred which generate a zigzag chain along with
the C-H O and C-H F chains (Figure 6, Table 4).
Group B (Set I and Set II). Compounds belonging to Group
B set I and II are either disordered20 or do not yield X-ray
diffraction quality crystals.
= θ2 = 165ꢀ] is observed in 2FA-3ClB, a Type II, Br
Br
3 3 3
contact [3.72, Å, θ1 = 172, θ2 = 110ꢀ] (sum of van der Waals
radii þ0.1 Å) is observed in 2FA-3Br. This rather unusual
feature could be attributed to the size of bromine, and a
detailed charge density analysis could bring out the finer
3 3 3
3 3 3
1582
dx.doi.org/10.1021/cg101544z |Cryst. Growth Des. 2011, 11, 1578–1596

Crystal Growth & Design
ARTICLE
Figure 3. (a) ORTEP of 2FA-2ClB with 30% ellipsoid probability and atom numbering scheme (b) N-H O hydrogen bond chains along the a-axis
3 3 3
(c) C-H F and C-H Cl interactions forming chains and dimer.
3 3 3 3 3 3
Figure 4. (a) ORTEP of 2FA-2BrB with 30% ellipsoid probability, atom numbering scheme, and intramolecular interaction depicted by open circles, (b)
N-H O hydrogen bond chains, C-H O and C-H Br interactions forming a wavelike pattern.
3 3 3 3 3 3 3 3 3
Group B (Set III). 3FA-4ClB and 3FA-4BrB are isostructural
and crystallize in the non-centrosymmetric orthorhombic space
bond involving H13 stabilizes the molecular conformation. The
N-H O hydrogen bonds form chains along the a-axis, and
3 3 3
group P212121 with Z = 4 (Table 5). Intramolecular C-H
O
further weak C-H F interactions (involving H5) form mo-
3 3 3
3 3 3
interaction (involving H13) stabilizes the molecular conforma-
lecular chains along the c-axis provide additional stability
tion. N-H O hydrogen bonds form molecular chain along
(Table 9). This set provides the hetero-halogen F X (Cl or
3 3 3
3 3 3
the a-axis. Further, the molecular packing is stabilized by C-
Br) [Type II, contacts are 3.189(4) and 3.160(2) Å for 4FA-2ClB
and 4FA-2BrB respectively and angles are θ1 = 178 and θ2 =
108ꢀ] interactions in this series of compounds to form layered
structures with tetramer unit formation (Figure 8, Table 10).
Group C (Set II). 4FA-3ClB and 4FA-3BrB are isostructural
with centrosymmetric monoclinic P21/c space group with Z = 4
H
O (involving H3) and C-H F (involving H9) interac-
3 3 3
3 3 3
tions also along the a-axis (Table 6). Additional homo-halogen
X
X (Cl, Br) of Type II geometry contacts [θ1 = 172, θ2 =
3 3 3
84ꢀ] link the N-H O chains (Figure 7, Table 7).
Group C (Set I). 4FA-2ClB and 4FA-2BrB are again isostruc-
tural and crystallize in centrosymmetric triclinic space group P1
3 3 3
(Table 8). An intramolecular C-H O bond involving H13 once
3 3 3
with Z = 2 (Table 8). An intramolecular C-H O hydrogen
again stabilizes the molecular conformation. The N-H
O
3 3 3
3 3 3
1583
dx.doi.org/10.1021/cg101544z |Cryst. Growth Des. 2011, 11, 1578–1596

Crystal Growth & Design
ARTICLE
Table 5. Crystallographic Information
hydrogen bond forms a molecular chain along the b-axis
(Table 9, Figure 9a). It is to be noted that stability in packing
3FA-4ClB
3FA-4BrB
is achieved through C-H π interactions (Figure 9b). Despite
3 3 3
the increased distances with respect to homo-halogen interac-
tion, the geometry is maintained as Type I for fluorine [θ1 = θ2 =
110ꢀ] and Type II for chlorine or bromine [θ1 = 163 and θ2 =
97ꢀ] (Table 10, Figure 9b).
formula
C
13H9NOFCl
C13H9NOFBr
294.1
formula weight
temperature K
size of crystal (mm)
CCDC no.
space group
a (Å)
249.7
292(2)
0.32 ꢀ 0.19 ꢀ 0.12
774787
P212121
4.941(4)
5.645(5)
40.123(3)
90
292(2)
0.18 ꢀ 0.16 ꢀ 0.11
765332
P212121
4.931(1)
5.671(1)
40.929(7)
90
Group C (Set III). 4FA-4BrB crystallizes in centrosymmetric
monoclinic space group P21/c with Z = 4 (Table 8). 4FA-4BrB is
nearly isostructural to the parameters, being 1.0 Å larger in the a-axis
and 5.9ꢀ lower in βangle compared to the lattice parameters for 4FA-
3ClB. As a consequence, the packing of molecules in the crystal
structure is similar to that of 4FA-3BrB. It is of interest to note that
the shift in bromine position from meta to para on the benzoyl ring
do not appear to be of any significance (Table 10 and Figure 9).
b (Å)
c (Å)
R (ꢀ)
β (ꢀ)
90
90
γ (ꢀ)
90
90
volume (Å3)
1119.2(2)
4
1144.7(2)
4
Z
density (g cm-3
)
1.48
1.71
μ (mm-1
)
0.335
3.585
F(000)
511.9
583.9
θmin, max (ꢀ)
hmin, max
2.0, 26.0
-6, 6
2.0, 25.5
-5, 5
kmin, max
-6, 6
-6, 6
lmin, max
-49, 49
11560
-49, 49
8452
no. of reflections measured
no. unique reflections
no. of parameter
2182
2104
154
154
R_all, R_obs
0.079, 0.068
0.148, 0.144
0.458, -0.209
1.209
0.075, 0.057
0.122, 0.117
0.627, -0.366
1.152
wR2_all, wR2_obs
ΔFmax, min (e Å-3
Figure 5. N-H O, C-H F (dimer) hydrogen bond chains and
3 3 3 3 3 3
)
X
X (Cl and Br) interactions along with C-H π form two
3 3 3
3 3 3
differed layered structures for 2FA-3BrB and 2FA-3ClB.
GOF
Figure 6. 2FA-4ClB, 2FA-4BrB, and 2FA-4IB depicting (a) homo-halogen X X (Cl, Br, and I) zigzig chain parallel to C-H F chains stabilized by
3 3 3 3 3 3
C-H O interaction (b) C-H O and C-H F exhibit dimer formation.
3 3 3 3 3 3 3 3 3
Table 6. Intra- and Intermolecular Interactions
crystal
D-H
A
D
H/Å
D
A/Å
H
A/Å
—D-H A/ꢀ
symmetry
x, y, z
3 3 3
3 3 3
0.93
3 3 3
3 3 3
3 3 3
3FA-4ClB
C13-H13 O1
2.865(5)
2.976(4)
3.438(5)
3.447(5)
2.868(8)
2.969(6)
3.442(8)
3.454(8)
2.36
2.19
2.57
2.54
2.37
2.19
2.57
2.54
113
151
156
167
114
151
156
166
3 3 3
N1-H1 O1
0.86
0.93
0.93
0.93
0.86
0.93
0.93
-1 þ x, y, z
-1 þ x, 1 þ y, z
-1 þ x, 1 þ y, z
x, y, z
3 3 3
C3-H3 O1
3 3 3
C9-H9 F1
3 3 3
3FA-4BrB
C13-H13 O1
3 3 3
N1-H1 O1
-1 þ x, y, z
-1 þ x, y, z
-1 þ x, y, z
3 3 3
C3-H3 O1
3 3 3
C9-H9 F1
3 3 3
1584
dx.doi.org/10.1021/cg101544z |Cryst. Growth Des. 2011, 11, 1578–1596

Crystal Growth & Design
ARTICLE
Table 7. Halogen Halogen Short Contact
3 3 3
crystal
C-X Y-C
X
Y/Å
—C-X Y/ꢀ
—C-Y X/ꢀ
symmetry
type
3 3 3
3 3 3
3 3 3
3 3 3
3FA-4ClB
3FA-4BrB
C4-Cl1 Cl1-C4
3.553(2)
3.657(2)
171
172
83
85
-x, y - 1/2, -z þ 1/2
-x, y - 1/2, -z þ 1/2
II
II
3 3 3
C4-Br1 Br1-C4
3 3 3
Table 8. Crystallographic Information
Set (I)
Set (II)
Set (III)
4FA-2ClB
4FA-2BrB
4FA-3ClB
4FA-3BrB
4FA-4BrB
formula
C
13H9NOFCl
C13H9NOFBr
294.1
C13H9NOFCl
249.7
C13H9NOFBr
294.1
C13H9NOFBr
294.1
formula weight
temperature K
size of crystal (mm)
CCDC no.
space group
a (Å)
249.7
292(2)
292(2)
292(2)
0.18 ꢀ 0.11 ꢀ 0.10
774785
P21/c
292(2)
0.49 ꢀ 0.32 ꢀ 0.18
765323
P21/c
292(2)
0.26 ꢀ 0.19 ꢀ 0.11
765324
P21/c
0.24 ꢀ 0.22 ꢀ 0.19
774784
P1
0.32 ꢀ 0.13 ꢀ 0.13
765333
P1
5.088(1)
9.123(1)
13.367(1)
105.304(5)
98.725(5)
99.351(5)
578.0(1)
2
5.091(1)
9.264(1)
13.411(2)
105.212(2)
98.890(3)
98.968(3)
590.1(1)
2
25.567(1)
5.436(1)
7.986(2)
90
25.959(6)
5.388(1)
8.183(2)
90
26.974(9)
5.297(2)
8.069(3)
90
b (Å)
c (Å)
R (ꢀ)
β (ꢀ)
γ (ꢀ)
volume (Å3)
98.554(3)
90
98.914(4)
90
93.089(6)
90
1097.7(3)
4
1130.8(1)
4
1151.3(3)
4
Z
density (g cm-3
)
1.43
1.66
1.51
1.73
1.70
μ (mm-1
)
0.324
3.477
0.341
3.629
3.564
F(000)
256.0
292.0
511.9
583.9
583.9
θmin, max (ꢀ)
hmin, max
kmin, max
2.4, 25.0
-6, 5
1.6,26.0
-6, 6
1.6, 25.7
-31, 30
-6, 6
2.4, 25.5
-29, 31
-6, 6
2.3, 26.0
-33, 32
-6, 6
-10, 10
-15, 15
8956
-11, 11
-16, 16
6172
lmin, max
-9, 9
-9, 9
-9, 9
no. of reflections measured
no. unique reflections
no. of parameter
14409
7932
11062
2021
2309
2086
2092
2250
154
154
154
154
154
R_all, R_obs
0.131, 0.090
0.249, 0.226
0.987, -0.294
0.967
0.042, 0.032
0.078, 0.075
0.478, -0.203
1.070
0.066, 0.040
0.105, 0.097
0.228, -0.206
1.039
0.044, 0.033
0.090, 0.087
0.597, -0.406
1.070
0.090, 0.050
0.124, 0.112
0.742, -0.242
1.041
wR2_all, wR2_obs
ΔFmax, min (eÅ-3
)
GOF
The next group of compounds considers the presence of a
fluorine atom at the benzoyl ring with varying halogens on the
amino side of the aromatic ring.
Group D (Set III). The chloro and iodo compounds [2FB-
4ClA and 2FB-4IA] in this set also do not form good quality
crystals for diffraction studies. 2FB-4BrA crystallizes in non-
centrosymmetric orthorhombic space group Pca21 with Z = 4
Group D (Set I). All compounds in this set are disordered and
are discussed in a private communication.20
(Table 11). Again, six-membered N-H F intramolecular
3 3 3
interaction stabilizes the molecular conformation. Once again
Group D (Set II). 2FB-3ClA and 2FB-3BrA are isostructural
and crystallize in noncentrosymmetric monoclinic Pn (Pc) space
group with Z = 2 (Table 11). Along with usual intramolecular
N-H O hydrogen bonds form molecular chains along the
3 3 3
b-axis. Additional weak C-H π (involving H6) and C-
3 3 3
Br π interactions hold the molecule together (Figure 13,
Table 12).
C-H O (involving H13), the molecular conformation is
3 3 3
3 3 3
stabilized by additional N-H F (involving H1) intramole-
3 3 3
Group E (Set I). 3FB-2ClA crystallizes in centrosymmetric
monoclinic space group P21/n with Z = 4 (Table 13). Intramo-
cular interaction. Indeed, the N-H F interaction forms a six-
3 3 3
membered intramolecular motif (Figure 10). The routine N-
lecular C-H O interaction confines the conformation of the
H
O hydrogen bond forms a chain along the b-axis. In 2FB-
3 3 3
3 3 3
molecule. N-H O hydrogen bonds form molecular chain
3ClA, C-H F and C-H Cl interactions provide further
stability to the packing generating a wavelike assembly of
molecules (Figure 11). It is of interest to note that in 2FB-
3 3 3
3 3 3
3 3 3
along the a-axis. The packing in the crystal lattice is mainly
through C-Cl π in 3FB-2ClA and C-Br π in 3FB-2BrA
3 3 3
3 3 3
(Figure 14). It is to be noted that both the packing features are
3BrA, there is a C-Br π interaction replacing the possible
3 3 3
almost similar except that the chlorine compound has short F
interactions, whereas the bromine compound has C-H
F
F
C-H Br interactions (Figure 12; Table 12). However, the
3 3 3
3 3 3
3 3 3
packing feature remains invariant.
1585
dx.doi.org/10.1021/cg101544z |Cryst. Growth Des. 2011, 11, 1578–1596

Crystal Growth & Design
ARTICLE
interactions which further stabilize the packing of the molecule in
the crystal lattice (Figure 14, Tables 14 and 15).
Group E (Set II). 3FB-3ClA and 3FB-3BrA crystallize in
centrosymmetric monoclinic space group P21/n with Z = 4
and are isostructural (Table 13). In addition to the intramole-
b-axis. Further hetero-halogen F Cl/Br contact of Type II [θ1
3 3 3
= 165ꢀ, θ2 = 92ꢀ] strengthens the molecular assembly generat-
ing a staircase-like arrangement (Figure 15, Tables 14 and 15).
Group E (Set III). Compounds belonging to these sets are
either disordered20 or do not yield X-ray diffraction quality
crystals.
Group F (Set I). 4FB-2ClA, 4FB-2BrA, and 4FB-2IA crystal-
lize in centrosymmetric monoclinic space group P21/c, P21/n,
and P21/c respectively with Z = 4 (Table 16). Intramolecular
cular C-H O (involving H13) interaction, the N-H
O
3 3 3
3 3 3
(involving H1) hydrogen bond form a molecular chain along the
C-H O interaction stabilizes the solid-state conformation
3 3 3
for 4FB-2ClA and 4FB-2BrA. The N-H O hydrogen bonds
3 3 3
form chains along the b-axis for 4FB-2ClA and 4FB-2BrA,
whereas it is along the c-axis for 4FB-2IA. In case of 4FB-2ClA,
additional C-H O (involving H6) and C-H Cl
3 3 3 3 3 3
(involving H3) interactions form a dimer layer arrangement
(Figure 16). A similar C-H O dimer also is observed in
3 3 3
4FB-2BrA; however, an additional hetero-halogen Br
F
3 3 3
Type II [θ1 = 161ꢀ, θ2 = 88ꢀ] interaction which links the
N-H O parallel chains results in a different packing feature
3 3 3
(Figure 17). 4FB-2IA is again different with C-I π chains
3 3 3
Figure 7. 3FA-4ClB and 3FA-4BrB show (a) homo-halogen X
(Cl, and Br) interaction acting as a link between the parallel chains
X
3 3 3
formed by N-H O, C-H O and C-H F hydrogen bonds
3 3 3 3 3 3 3 3 3
(b) C-H O and C-H F hydrogen bond depicting hetero-dimer
3 3 3 3 3 3
Figure 8. N-H O, C-H F hydrogen bond chains, and F Cl/
3 3 3 3 3 3 3 3 3
formation.
Table 9. Intra- and Intermolecular Interactionsa
Br interactions form layered packing for 4FA-2ClB and 4FA-2BrB.
D-H
A
D
H/Å
D
A/Å
H
A/Å
—D-H A/ꢀ
symmetry
3 3 3
3 3 3
3 3 3
3 3 3
3 3 3
4FA-2ClB
4FA-2BrB
4FA-3ClB
C13-H13 O1
0.93
2.881(6)
2.889(5)
3.225(7)
2.878(3)
2.892(3)
3.298(7)
2.940(3)
3.300(2)
3.623(3)
3.660(3)
3.649(3)
3.665(2)
2.940(4)
3.255(3)
3.648(3)
2.942(5)
3.164(4)
3.641(5)
3.610(5)
3.622(5)
3.656(4)
2.44
2.09
2.62
2.43
2.10
2.66
2.47
2.46
2.92
2.96
2.98
2.98
2.48
2.41
2.94
2.50
2.33
2.90
2.91
2.93
2.95
109
154
126
109
153
126
112
165
134
133
131
132
111
166
134
109
164
137
133
132
133
x, y, z
3 3 3
N1-H1 O1
0.86
0.93
0.93
0.86
0.93
0.93
0.86
0.93
0.93
0.93
0.93
0.93
0.86
0.83
0.93
0.86
0.93
0.93
0.93
0.93
1þx, y, z
3 3 3
C5-H5 F1
x, y, z þ 1
3 3 3
C13-H13 O1
x, y, z
3 3 3
N1-H1 O1
-1 þ x, y, z
3 3 3
C5-H5 F1
x, y, z þ 1
3 3 3
C13-H13 O1
x, y, z
3 3 3
N1-H1 O1
x, -1 þ y, z
3 3 3
C3-H3 Cg1
x, -1/2 - y, -1/2 þ z
x, 1/2 - y, 1/2 þ z
x, -1/2 - y, 1/2 þ z
x, 1/2 - y, -1/2 þ z
x, y, z
3 3 3
C6-H6 Cg1
3 3 3
C10-H10 Cg2
3 3 3
C13-H13 Cg2
3 3 3
4FA-3BrB
4FA-4BrB
C13-H13 O1
3 3 3
N1-H1 O1
x, 1 þ y, z
x, 3/2 - y, 1/2 þ z
x, y, z
3 3 3
C3-H3 Cg1
3 3 3
C13-H13 O1
3 3 3
N1-H1 O1
x, 1 þ y, z
3 3 3
C3-H3 Cg1
x, 3/2 - y, 1/2 þ z
x, 1/2 - y, -1/2 þ z
x, 3/2 - y, -1/2 þ z
x, 1/2 - y, 1/2 þ z
3 3 3
C6-H6 Cg1
3 3 3
C10-H10 Cg2
3 3 3
C13-H13 Cg2
3 3 3
a Cg1 = centroid of C1-C6 atom, Cg2 = centroid of C8-C13 atom.
1586
dx.doi.org/10.1021/cg101544z |Cryst. Growth Des. 2011, 11, 1578–1596

Crystal Growth & Design
ARTICLE
Table 10. Halogen Halogen Short Contact
3 3 3
C-X Y-C
X
Y/Å
—C-X Y/ꢀ
—C-Y X/ꢀ
symmetry
type
3 3 3
3 3 3
3 3 3
3 3 3
4FA-2ClB
4FA-2BrB
4FA-3ClB
C11-F1 Cl1-C6
3.189(4)
3.160(2)
2.963(2)
3.609(1)
2.977(2)
3.706(2)
3.791(3)
2.962(3)
109
178
107
165
107
162
121
109
177
108
112
95
-x, -y þ 1, -z
II
II
I
3 3 3
C6-Br1 F1-C11
-x, -y þ 1, -z þ 1
3 3 3
C11-F1 F1A-C11A
-x þ 1, y - 1/2, -z þ 3/2
-x, þy - 1/2, -z þ 1/2
-x, þy þ 1/2, -z þ 1/2
-x þ 1, y - 1/2, -z þ 3/2
-x, þy - 1/2, -z þ 3/2
-x þ 1, y - 1/2, -z þ 1/2
3 3 3
C5-Cl1 Cl1-C5
II
I
3 3 3
4FA-3BrB
4FA-4BrB
C11-F1 F1-C11
113
99
3 3 3
C5-Br1 Br1-C5
II
II
I
3 3 3
C4-Br1 Br1-C4
149
114
3 3 3
C11-F1 F1-C11
3 3 3
Table 11. Crystallographic Information
Set (II)
Set (III)
2FB-3ClA
2FB-3BrA
2FB-4BrA
formula
C13H9NOFCl
249.7
C13H9NOFBr
294.1
C13H9NOFBr
294.1
formula weight
temperature K
size of crystal (mm)
CCDC no.
space group
a (Å)
292(2)
0.28 ꢀ 0.22 ꢀ 0.19
774790
Pn
292(2)
0.37 ꢀ 0.28 ꢀ 0.16
765325
Pc
292(2)
0.26 ꢀ 0.25 ꢀ 0.04
765326
Pca21
5.265(2)
4.503(1)
23.769(4)
90
4.779(3)
5.078(3)
23.792(1)
90
8.159(3)
5.302(2)
26.843(1)
90
b (Å)
c (Å)
R (ꢀ)
β (ꢀ)
γ (ꢀ)
volume (Å3)
94.293(8)
90
92.498(1)
90
90
90
561.9(2)
2
576.9(2)
2
1161.3(2)
4
Z
density (g cm-3
)
1.48
1.69
1.68
μ (mm-1
)
0.333
3.556
3.534
F(000)
256.0
292.0
583.9
θmin, max (ꢀ)
hmin, max
1.7, 26.0
-6, 6
3.4, 25.3
-5, 5
3.0, 28.1
-9, 10
-6, 6
kmin, max
-4, 5
-6, 6
lmin, max
-29, 28
8502
-28, 28
5077
-34, 35
9110
no. of reflections measured
no. unique reflections
no. of parameter
2157
2053
2723
154
155
158
R_all, R_obs
0.039, 0.035
0.084, 0.083
0.204, -0.128
1.849
0.104, 0.077
0.185, 0.171
1.704, -0.405
1.043
0.104, 0.047
0.108, 0.089
0.389, -0.221
1.006
wR2_all, wR2_obs
ΔFmax, min (e Å-3
)
GOF
interconnected through C-H F (involving H5) hydrogen
C-H O, C-H π along with π π interactions stabilize
3 3 3
3 3 3
3 3 3
3 3 3
bonds to form a “ladder like” arrangement (Figure 17). Addi-
and force the molecules to arrange in a manner such that there
are no halogen interactions (Figure 18). 4FB-3IA is different and
tional C-H O (involving H10) and C-H π (involving
3 3 3
3 3 3
H9) interactions enhance the stability of assembly in this
structure (Table 17).
prefers halogen involved interactions. N-H O hydrogen
3 3 3
bonds form infinite molecular chain along the b-axis. C-I
π
3 3 3
Group F (Set II). 4FB-3ClA and 4FB-3BrA crystallize in
centrosymmetric monoclinic space group P21/c with Z = 4 and
are isostructural, whereas 4F-3IA crystallizes in centrosymmetric
orthorhombic space group Pbca with Z = 8 (Table 16). In the
and C-H F interactions form parallel chains individually. It is
3 3 3
to be noted that additionally, the C-H π and π π stacks
3 3 3 3 3 3
also stabilize the molecular packing. Two consecutive C-I
π
3 3 3
and C-H F interactions form a helical structure along the b-
3 3 3
case of 4FB-3ClA and 4FB-3BrA, the N-H O hydrogen
axis (Table 17, Figure 19).
3 3 3
bonds form a molecular chain along the c-axis and the O1 forms
Group F (Set III). 4FB-4ClA crystallizes in centrosymmetric
monoclinic space group P21/c with Z = 4 (Table 16).
bifurcated hydrogen bonds (involving H2 and H1). Additional
1587
dx.doi.org/10.1021/cg101544z |Cryst. Growth Des. 2011, 11, 1578–1596

Crystal Growth & Design
ARTICLE
Figure 9. 4FA-3ClB and 4FA-3BrB show (a) N-H O, F F, and Cl/Br Br/Cl form parallel hydrogen bond chains, and (b) the C-H
3 3 3 3 3 3 3 3 3
π
3 3 3
chain forms a separate layered structure.
Figure 10. ORTEP drawn with 30% ellipsoid probability depicting six-membered N-H F and C-H O intramolecular interactions as dotted
3 3 3 3 3 3
lines (a) 2FB-3ClA (b) 2FB-2BrA.
Figure 12. 2FB-3BrA shows a wavelike assembled pattern through edge
C-Br π and C-H F interactions.
3 3 3 3 3 3
θ1 = θ2 = 153ꢀ] enhance the stability of packing. The participation
of all interactions forms an unusual “cone type” arrangement along
the c-axis (Figure 20; Tables 17 and 18). 4FB-4BrA crystallizes in
non-centrosymmetric orthorhombic space group P21212 (Z = 8)
Figure 11. 2FB-3ClA shows a wavelike assembly of C-H Cl and
3 3 3
C-H F interactions.
3 3 3
Intramolecular C-H O (involving H13) is present forming a
3 3 3
with Z0 = 2. C-H O (involving H13 and H130) interactions
six-membered ring and N-H O hydrogen bonds form molec-
3 3 3
3 3 3
ular chain which is further assisted by C-H O (involving H2),
stabilize the molecular conformation and N-H O (involving
3 3 3
3 3 3
H1 and H10) hydrogen bonds form molecular chain along the c-
axis. The C-H F (involving H5) and C-H π (involving
C-H F (involving H6), and π π stacking. In addition,
3 3 3
3 3 3
homo-halogen Cl Cl directional contacts of Type I [3.35 Å,
3 3 3
3 3 3
3 3 3
1588
dx.doi.org/10.1021/cg101544z |Cryst. Growth Des. 2011, 11, 1578–1596

Crystal Growth & Design
ARTICLE
Table 12. Intra- and Intermolecular Interactionsa
crystal
D-H
A
D
H/Å
D
A/Å
H
A/Å
—D-H A/ꢀ
symmetry
3 3 3
N1-H1 F1
3 3 3
0.86
3 3 3
3 3 3
3 3 3
2FB-3ClA
2.752(2)
2.878(3)
3.128(2)
3.611(3)
3.295(3)
2.748(1)
2.904(1)
2.973(2)
3.313(3)
5.323(3)
2.750(5)
3.198(5)
3.589(6)
5.527(4)
2.15
2.35
2.41
2.97
2.66
2.17
2.40
2.23
2.63
127
115
142
127
125
124
114
144
130
161
126
151
129
159
x, y, z
x, y, z
3 3 3
C13-H13 O1
0.93
0.86
0.93
0.93
0.86
0.93
0.86
0.93
3 3 3
N1-H1 O1
-1 þ x, y, z
x - 1/2, -y þ 1, z þ 1/2
x - 1, y, z
3 3 3
C4-H4 Cl1
3 3 3
C5-H5 F1
3 3 3
2FB-3BrA
2FB-4BrA
N1-H1 F1
3 3 3
C13-H13 O1
x, y, z
x, y, z
3 3 3
N1-H1 O1
x, -1 þ y, z
x þ 1, y, z
3 3 3
C5-H5 F1
3 3 3
C12-Br1 C4
3 3 3
3.510(2)
2.15
N1-H1 F1
0.86
0.86
x, y, z
3 3 3
N1-H1 O1
2.41
x, 1 þ y, z
1/2 þ x, 1 - y, z
-x þ 2, -y þ 1, z - 1/2
3 3 3
C6-H6
Cg1
2.93
3 3 3
C11-Br1 C5
3.70
3 3 3
a Cg1 = centroid of C1-C6 ring.
over different positions of the molecule, that is, changes in
molecular conformation and also the modifications associated
with crystal packing. Furthermore, isostructurality32 plays a very
important role because it so happens that in certain cases
changing the position of an atom in the molecule does not lead
to any changes in the crystal packing, whereas in certain cases
there is a pronounced change in crystal packing. These issues
are further complicated by the appearance of polymorphs in
such molecules which again contributes to the complexity
associated with small molecules whose crystal structures are
being determined. The weak, soft, and flexible weak interactions
play a pivotal role in crystal nucleation and growth processes
resulting in different physical forms and structures having
multiple molecules in the asymmetric unit (high Z0).33 The
area of crystal engineering has this limitation wherein we can
make a conceptual prediction from the available structural data
for a series of molecules (containing a given molecular
framework), but there is no answer to what will be the observed
when a given functional group is changed in a given position or
moved over different portions of the molecule, this inability
being due to the lack of a robust crystal structure prediction
model which will relate the molecular structure with the crystal
structure. Keeping in mind the above-mentioned limitations, it
is indeed noteworthy to explore the supramolecular attributes
which accompany such crystallographic determinations in
terms of changes in molecular conformation, crystal packing,
isostructurality, and elucidating the diversity associated with
weak interactions.
Figure 13. 2F-4BrA form C-H π chains interconnected through
3 3 3
edge C-Br π directional contact.
3 3 3
H130, H12, H100, H6, H60 and H30) interactions enhance the
stability of packing. The presence of C-H π appears to weaken
3 3 3
the homo-halogen halogen interactions though the direction-
3 3 3
ality is maintained (Figure 21, Tables 17 and 18).
’ DISCUSSION
The changes in molecular conformation associated with
different halogen atoms follow certain trends. The dihedral
angles between plane1-plane2 lies between 2 and 6ꢀ for all
the compounds in Group A (Table S1, Supporting Information:
Set I, II, III [fluoro in ortho position]; except 2FA-2BrB)
indicating planarity assisted by electron delocalization between
the benzoyl moiety and the amido functional group. A similar
feature is observed for Set III (Group B). However, the presence
of a fluorine atom at the para position of the aniline ring results in
loss of parallelism and the corresponding dihedrals between
plane1-plane2 lie in the range of 60-80ꢀ [Table S1, Supporting
Information: Group C, Set I, II, III]. Thus, the electronic features
play an important role in deciding the equilibrium geometry.
TheanalysisofallthestructuresstudiedinTables2,5,8,11,13
and 16 brings out a few generalizations in halogen-substituted
benzanilides. It is also of interest to compare the present series
of crystal and molecular structure determinations on mixed-
halogenated benzanilides with the parent compound, that is, the
unsubstituted benzanilide30 along with fluoro-31 and chloro-
substituted benzanilides.17 It is already well established that the
prediction of crystal structure of a compound, given its molec-
ular connectivity diagram, is still in its fancy. There are two
important questions which need to be addressed when one is
dealing with a large number of isomeric molecules which are
obtained by simply varying the position of the functional group
1589
dx.doi.org/10.1021/cg101544z |Cryst. Growth Des. 2011, 11, 1578–1596

Crystal Growth & Design
ARTICLE
Table 13. Crystallographic Information
Set (I)
Set (II)
3FB-2ClA
3FB-2BrA
3FB-3ClA
3FB-3BrA
formula
C13H9NOFCl
249.7
C13H9NOFBr
294.1
C13H9NOFCl
249.7
C13H9NOFBr
294.1
formula weight
temperature K
size of crystal (mm)
CCDC no.
space group
a (Å)
292(2)
292(2)
292(2)
292(2)
0.21 ꢀ 0.07 ꢀ 0.06
774788
P21/n
0.24 ꢀ 0.16 ꢀ 0.10
640040
P21/n
0.22 ꢀ 0.12 ꢀ 0.11
774791
P21/n
0.15 ꢀ 0.12 ꢀ 0.1
765327
P21/n
4.881(2)
11.574(1)
19.951(2)
90
11.178(1)
4.768(5)
21.824(2)
90
14.983(2)
4.910(2)
15.414(2)
90
15.198(6)
4.903(2)
15.498(2)
90
b (Å)
c (Å)
R (ꢀ)
β (ꢀ)
γ (ꢀ)
volume (Å3)
92.255(1)
90
94.714(2)
90
93.383(2)
90
93.949(7)
90
1126.3(1)
4
1159.4(3)
4
1131.9(1)
4
1152.2(3)
4
Z
density (g cm-3
)
1.47
1.68
1.46
1.70
μ (mm-1
)
0.333
3.539
0.331
3.562
F (000)
511.9
583.9
511.9
583.9
θmin, max (ꢀ)
hmin, max
2.0, 26.0
-6, 6
1.9, 25.7
-13, 13
-5, 5
1.8, 26.0
-18, 18
-6, 6
1.8, 26.0
-18, 18
-6, 6
kmin, max
-14, 14
-24, 24
11458
lmin, max
-26, 26
8253
-19, 19
10757
-19, 18
11288
no. of reflections measured
no. unique reflections
no. of parameter
2202
2192
2213
2254
154
154
154
154
R_all, R_obs
0.064, 0.046
0.115, 0.108
0.387, -0.231
1.095
0.041, 0.031
0.073, 0.069
0.357, -0.284
1.036
0.067, 0.055
0.143, 0.135
0.433, -0.266
1.070
0.082, 0 0.054
0.117, 0.109
0.575, -0.314
1.097
wR2_all, wR2_obs
ΔFmax, min (e Å-3
)
GOF
Figure 14. 3FB-2ClA prefers edge C-Cl π and F F, whereas 3FB-2BrA prefers C-Br π and C-H F interactions.
3 3 3 3 3 3 3 3 3 3 3 3
The appearance of a six-membered C-H O intramolecular
C-H O), additional halogen involved contacts appear to keep
3 3 3
3 3 3
interaction in almost all crystal structures discussed above in-
dicates that this particular interaction stabilizes the molecular
conformation. The reason appears to be essentially geometrical as
the N-H group prefers to be trans to the CdO group. In those
the molecular conformation intact, for example, in 2FA-2ClB,
2FB-4BrA, and 4FB-3IA. N-H F intramolecular interactions
3 3 3
have been extensively studied in recent times as possible interac-
tions rigidifying molecular conformation.12,13 The presence of six-
cases where intramolecular C-H O interactions are not
membered N-H F intramolecular interaction is observed in
3 3 3
3 3 3
present (as decided based on distance between H O and angle
structures 2FB-3ClA, 2FB-3BrA, and 2FB-4BrA. Such
3 3 3
1590
dx.doi.org/10.1021/cg101544z |Cryst. Growth Des. 2011, 11, 1578–1596

Crystal Growth & Design
ARTICLE
Table 14. Intra- and Intermolecular Interactions
crystal
D-H
A
D
H/Å
D
A/Å
H
A/Å
—D-H A/ꢀ
symmetry
3 3 3
3 3 3
0.93
3 3 3
3 3 3
3 3 3
3FB-2ClA
C13-H13 O1
2.909(3)
2.900(2)
5.414(3)
2.921(3)
2.915(3)
4.054(3)
3.406(1)
2.880(3)
2.879(2)
2.882(6)
2.868(4)
2.46
2.11
110
153
168
110
147
170
148
109
154
109
153
x, y, z
-1 þ x, y, z
1/2 - x, 1/2 þ y, 1/2 - z
x, y, z
3 3 3
N1-H1 O1
0.86
3 3 3
C9-Cl1 C12
3.415(1)
2.48
3 3 3
3FB-2BrA
C13-H13 O1
0.93
0.86
3 3 3
N1-H1 O1
2.16
x, -1 þ y, z
x, -1 þ y, z
-x, -y þ 1, -z
x, y, z
3 3 3
C9-Br1 C4
3.36
3 3 3
C11-H11 F1
0.93
0.93
0.86
0.93
0.86
2.57
3 3 3
3FB-3ClA
3FB-3BrA
C13-H13 O1
2.44
3 3 3
N1-H1 O1
2.08
x, -1 þ y, z
x, y, z
3 3 3
C13-H13 O1
2.44
3 3 3
O1
N1-H1
2.07
x, -1 þ y, z
3 3 3
Table 15. Halogen Halogen Short Contact
3 3 3
crystal
C-X Y-C
X
Y/Å
—C-X Y/ꢀ
—C-Y X/ꢀ
3 3 3
symmetry
type
3 3 3
3 3 3
3 3 3
3FB-2ClA
3FB-3ClA
3FB-3BrA
C3-F1 F1-C3
2.918(2)
3.251(2)
3.263(3)
159
165
165
159
-x þ 1, -y, -z þ 1
x - 1/2, -y þ 1/2, z þ 1/2
x - 1/2, -y þ 1/2, z þ 1/2
I
3 3 3
C12-Br1 F1-C3
92
92
II
II
3 3 3
C12-Br1 F1-C3
3 3 3
interactions crystallize in a variety of space groups (both
centrosymmetric and noncentrosymmetric) belonging either
to the triclinic, monoclinic, and orthorhombic crystal system,
respectively. The following series of compounds are isostruc-
tural to each other having similarity in molecular conformation
and crystal packing: Group A: Set II (2FA-3ClB, 2FA-3BrB);
Set III: (2FA-4ClB, 2FA-4BrB, 2FA-4IB). Group B: Set III
(3FA-4ClB, 3FA-4BrB, 3FA-4IB). Group C: Set I (4FA-2ClB,
4FA-2BrB); Set II (4FA-3ClB, 4FA-3BrB, 4FA-4BrB). Group D:
Set II (2FB-3ClA, 2FB-3BrA); Group E: Set II (3FB-3ClA, 3FB-
3BrA).
The interaction of utmost importance in the formation of
supramolecular assemblies in these benzanilides is the N-
H
O hydrogen bond. Indeed, this interaction forms chains
3 3 3
in the crystal lattice essentially along a particular crystallographic
axis. The supporting interactions, involving halogens, like for
Figure 15. 3F-3ClA and 3F-3BrA prefer hetero-halogen Cl/Br
interaction to form a staircase arrangement.
F
3 3 3
example C-H X, C-X π, and X X, develop depend-
3 3 3 3 3 3 3 3 3
ing on the size of the halogen atom. It is also to be noted that in
the case of compounds which display C-H O, C-H π,
3 3 3
3 3 3
and π π interactions, the propensity of formation of halogen
3 3 3
interactions get reduced; more often than not in these cases
halogens appear at distances more than the sum of van der Waals
radii.35 However, the geometry still appears to be favorable. F
and Cl prefer to have C-H F and C-H Cl contact,
3 3 3
3 3 3
whereas Br and I prefer to have C-Br π and C-I
π
3 3 3
3 3 3
interactions.
There is a higher propensity for the formation of homo-
halogen halogen interactions in comparison to hetero-halo-
3 3 3
gen halogen interactions. 4FA-2ClB and 4FA-2BrB form
3 3 3
Cl F and Br F short hetero-halogen contacts in the crystal
3 3 3
3 3 3
lattice. The heavy halogens are polarized in the polar region
(along the C-X vector) having a positive electrostatic potential
and a negative electrostatic potential in the equatorial region
(perpendicular to the C-X vector). The atomic size, polariza-
tion, and radial anisotropy increase in the order Cl < Br < I,
whereas electronegativity changes are in the reverse order.36
Thus, in the case of unsymmetrical interhalogen interactions, for
Figure 16. 4FB-2ClA prefers the alternate dimer arrangement through
C-H Cl and C-H O interactions.
3 3 3 3 3 3
interactions have been characterized in detail using NMR and
DFT studies performed on fluorinated benzanilides.34
The mixed halogenated compounds exhibit isostructurality in
the solid state and depending on the nature of intermolecular
1591
dx.doi.org/10.1021/cg101544z |Cryst. Growth Des. 2011, 11, 1578–1596

Crystal Growth & Design
ARTICLE
Table 16. Crystallographic Information
Set (I)
4FB-2BrA
C13H9NOFCl C13H9NOFBr C13H9NOFI
Set (II)
Set (III)
4FB-4BrA
C13H9NOFCl C13H9NOFBr
4FB-2ClA
4FB-2IA
4FB-3ClA
4FB-3BrA
4F-3IA
4FB-4ClA
formula
C13H9NOFCl C13H9NOFBr C13H9NOFI
formula weight
temperature K
size of crystal (mm)
249.7
294.1
341.1
249.7
294.1
341.1
249.7
294.1
292(2)
0.28 ꢀ 0.23
ꢀ 0.19
774789
P21/c
292(2)
0.56 ꢀ 0.10
ꢀ 0.07
640038
P21/n
292(2)
0.27 ꢀ 0.24
ꢀ 0.21
774781
P21/c
292(2)
0.29 ꢀ 0.22
ꢀ 0.21
774778
P21/c
292(2)
0.37 ꢀ 0.27
ꢀ 0.1
765328
P21/c
292(2)
0.28 ꢀ 0.23
ꢀ 0.18
774782
Pbca
292(2)
0.28 ꢀ 0.21
ꢀ 0.18
774779
P21/c
292(2)
0.27 ꢀ 0.15
ꢀ 0.44
640041
P21212
15.276(2)
28.568(4)
5.346(2)
90
CCDC no.
space group
a (Å)
9.104(3)
4.826(1)
26.011(2)
90
15.691(2)
4.764(2)
16.528(2)
90
18.774(4)
7.107(2)
9.282(2)
90
12.650(1)
9.531(1)
9.989(3)
90
12.809(2)
9.619(1)
10.009(1)
90
9.201(1)
9.941(1)
27.444(2)
90
12.095(2)
9.7867(1)
9.912(2)
90
b (Å)
c (Å)
R (ꢀ)
β (ꢀ)
γ (ꢀ)
volume (Å3)
90.940(3)
90
107.697(2)
90
93.284(5)
90
102.072(2)
90
103.343(2)
90
90
93.510(6)
90
90
90
90
1142.8(1)
4
1177.1(2)
4
1236.4(2)
4
1177.8(1)
4
1199.9(3)
4
2510.3(2)
8
1171.1(2)
4
2333.09(6)
8
Z
density (g cm-3)
1.45
1.66
1.83
1.41
1.63
1.80
1.42
1.67
μ (mm-1
)
0.328
3.486
2.584
0.318
3.420
2.546
0.320
3.518
F (000)
511.9
583.9
655.9
511.9
583.9
1311.9
1.5, 25.0
-10, 9
-11, 10
-32, 32
10147
511.9
1167.8
1.4, 25.0
-18, 18
-33, 33
-6,6
θmin, max (ꢀ)
hmin, max
3.1, 26.0
-11, 11
-5, 5
1.6, 26.0
-17, 19
-5, 5
1.1, 25.7
-22, 22
-8, 6
2.7, 26.0
-15, 14
-11, 11
-7, 12
8929
2.7, 25.5
-15, 15
-11, 11
-12, 12
11587
3.3, 26.0
-14, 14
-12, 12
-12, 12
9368
kmin, max
lmin, max
-32, 32
11776
-20, 20
8598
-7, 11
9312
no. of reflections
measured
22379
no. unique reflections. 2240
2304
2359
2317
2222
2201
2299
4114
no. of parameter
R_all, R_obs
154
154
155
155
158
154
154
307
0.063, 0.047
0.133, 0.127
0.066, 0.045
0.123, 0.115
0.057, 0.040
0.116, 0.095
0.066, 0.046
0.157, 0.135
0.051, 0.035
0.087, 0.083
0.068, 0.043
0.110, 0.096
0.084, 0.044
0.115, 0.105
0.088, 0.049
0.136, 0.107
wR2_all, wR2_obs
ΔFmax, min (e Å-3
GOF
)
0.619, -0.265 0.874, -0.437 0.788, -0.437 0.254, -0.259 0.516, -0.489 1.726, -1.350 0.147, -0.233 0.707, -0.449
1.033 1.012 1.162 1.118 1.030 1.030 0.894 1.042
Figure 17. (a) 4FB-2BrA show hetero-halogen Br F short contact which links the N-H O parallel infinite chains and (b) weak C-H
3 3 3 3 3 3
O
3 3 3
dimer arrangement, (c) 4FB-2IA forms C-I π molecular chains which are interconnected through C-H F interactions.
3 3 3 3 3 3
1592
dx.doi.org/10.1021/cg101544z |Cryst. Growth Des. 2011, 11, 1578–1596

Crystal Growth & Design
ARTICLE
Table 17. Intra- and Intermolecular Interactionsa
crystal
D-H
A
D
H/Å
D
A/Å
H
A/Å
—D-H A/ꢀ
symmetry
3 3 3
3 3 3
0.93
3 3 3
3 3 3
3 3 3
4FB-2ClA
C13-H13 O1
2.902(3)
2.920(2)
3.461(3)
2.895(5)
2.880(4)
3.471(3)
2.937(4)
3.335(8)
3.418(7)
5.442(5)
3.702(6)
2.952(2)
3.525(1)
3.370(3)
3.744(3)
3.8771(1)
2.968(3)
3.520(2)
3.398(3)
3.7558(1)
3.983(2)
2.941(5)
5.612(5)
3.222(6)
3.641(6)
3.744(3)
2.856(2)
2.881(2)
3.201(2)
3.494(3)
3.685(1)
3.759(1)
3.140(7)
3.146(7)
2.899(7)
2.921(7)
3.310(7)
3.682(7)
3.650(7)
3.661(7)
3.659(7)
3.595(7)
3.578(7)
3.571(7)
2.47
2.13
2.64
2.43
2.13
2.67
2.10
2.51
2.60
109
153
146
111
145
146
166
148
144
143
154
159
151
138
x, y, z
x, -1 þ y, z
-x þ 1, -y þ 1, -z þ 1
x, y, z
3 3 3
N1-H1 O1
0.86
0.93
0.93
0.86
0.93
0.86
0.93
0.93
3 3 3
C6-H6 O1
3 3 3
4FB-2BrA
4FB-2IA
C13-H13 O1
3 3 3
N1-H1 O1
x, -1 þ y, z
3 3 3
C6-H6 O1
-x þ 1, -y þ 1, -z þ 1
x, 3/2 - y, -1/2 þ z
1 - x, -1/2 þ y, 3/2 - z
-x, -y þ 2, -z þ 1
x, 3/2 - y, 1/2 þ z
x, 3/2 - y, -1/2 þ z
x, 3/2 - y, -1/2 þ z
x, -y þ 1/2 þ 1, z - 1/2
x, -y þ 1/2 þ 1, z - 1/2
-x, 1 - y, -z
3 3 3
N1-H1 O1
3 3 3
C5-H5 F1
3 3 3
C10-H10 O1
3 3 3
C13-I1 Cg2
3.620(2)
2.84
3 3 3
C9-H9 Cg1
0.93
0.86
0.93
0.93
3 3 3
4FB-3ClA
4FB-3BrA
4FB-3IA
N1-H1 O1
2.13
3 3 3
C2-H2 C13
2.68
3 3 3
C2-H2 O1
2.61
3 3 3
Cg1 Cg1
3 3 3
Cg2 Cg2
-x, 2 - y, -z
3 3 3
N1-H1 O1
0.86
0.93
0.93
2.18
2.67
2.63
164
151
140
x, 1/2 - y, 1/2 þ z
x, -y þ 1/2 þ 1, z - 1/2
x, -y þ 1/2 þ 1, z - 1/2
-x, 1 - y, 1 - z
1 - x, -y, 1 - z
1/2 - x, 1/2 þ y, z
1 - x, -1/2 þ y, 1/2 - z
-x þ 1/2, y - 1/2, z
1 þ x, y, z
3 3 3
C2-H2 C13
3 3 3
C2-H2 O1
3 3 3
Cg1 Cg1
3 3 3
Cg2
Cg2
3 3 3
N1-H1 O1
0.86
2.12
3.54
2.63
2.93
160
168
122
134
3 3 3
C12-I1 Cg2
3 3 3
C5-H5 F1
0.93
0.93
3 3 3
C10-H10 Cg1
3 3 3
Cg1 Cg1
-x, 1 - y, -z
3 3 3
4FB-4ClA
C13-H13 O1
0.93
0.86
0.93
0.93
2.37
2.04
2.49
2.63
113
166
133
154
x, y, z
3 3 3
N1-H1 O1
x, 3/2 - y, 1/2 þ z
x, 3/2 - y, 1/2 þ z
-x, y - 1/2, -z þ 1/2
-x, 2 - y, 1 - z
1 - x, 1 - y, 1 - z
x, y, -1 þ z
3 3 3
C2-H2 O1
3 3 3
C6-H6 F1
3 3 3
Cg1 Cg1
3 3 3
Cg2 Cg2
3 3 3
4FB-4BrA
N1-H1 O1
0.86
0.86
0.93
0.93
0.93
0.93
0.93
0.93
0.93
0.93
0.93
0.93
2.34
2.34
2.44
2.45
2.59
2.98
2.92
2.93
2.98
2.92
2.92
2.92
154
155
110
112
133
134
136
137
131
130
129
129
3 3 3
N10-H10
O10
x, y, 1 þ z
3 3 3
C13-H13 O1
C130-H130
x, y, z
3 3 3
O10
x, y, z
3 3 3
C5H5 F1
x, y - 1, z - 1
3 3
C30-H30
Cg1
-1/2 þ x, 1/2 - y, 2 - z
x, y, 1 þ z
x, y, -1 þ z
3 3 3
C6-H6 Cg4
3 3 3
C60-H60
Cg2
3 3 3
C10-H10 Cg3
x, y, z
3 3 3
C100-H100
Cg1
x, y, z
3 3 3
C12-H12 Cg4
1/2 þ x, 1/2 - y, 2 - z
-1/2 þ x, 1/2 - y, 1 - z
3 3 3
C130-H130
Cg2
3 3 3
a Cg1 = centroid of C1-C6 ring, Cg2 = centroid of C8-C13 ring, Cg3 = centroid of C10-C60. Cg4 = centroid of C50-C130 ring.
Table 18. Halogen Halogen Short Contact
3 3 3
C-X Y-C
X
Y/Å
—C-X Y/ꢀ
—C-Y X/ꢀ
symmetry
type
3 3 3
3 3 3
3 3 3
3 3 3
4FB-2BrA
4FB-4ClA
4FB-4BrA
C9-Br1 F1-C3
3.265(1)
3.356(2)
3.741(2)
2.952(1)
161
153
133
104
88
153
138
120
-x þ 1/2, þy - 1/2, -z þ 3/2
-x þ 1, -y, -z þ 1
x, y, z - 1
II
I
3 3 3
C11-Cl1 Cl1-C11
3 3 3
C11-Br1 Br10-C110
I
3 3
C4-F1 F10-C40
x, yþ1, z
I
3 3
1593
dx.doi.org/10.1021/cg101544z |Cryst. Growth Des. 2011, 11, 1578–1596

Crystal Growth & Design
ARTICLE
Figure 18. 4FB-3ClA and 4FB-3BrA prefer (a) bifurcated C-H O and C-H π interactions, (b) lead to cross folded geometry with N-H
O
3 3 3
3 3 3
3 3 3
and π π stacking without the participation of halogen interactions.
3 3 3
example, C-Cl F-C, the negative equatorial part of the
Hetero-halogen halogen interactions on the other hand are
3 3 3
3 3 3
lighter halogen fluorine preferentially approaches the positive
polar region of the heavier halogen bromine37 and hence the
observed Type II geometry. Furthermore, 3FB-3ClA and 3FB-
3BrA also exhibit such intermolecular hetero-halogen contacts. It
predominately of Type II geometry, and this is due to the greater
polarizability of the electron density associated with the heavier
halogens (Table 19). It is of interest to note that the concept of
halogen bonding involving Br/I O/N short contacts is well
3 3 3
has been observed that halogen halogen contacts direct non-
established. In contrast, the occurrence of interactions involving
3 3 3
centrosymmetric packing of dipolar organic molecules in the
solid state involving different geometrical arrangements,38 and a
similar packing feature is observed in the present halogen-
substituted benzanilides wherein in addition to strong N-
mixed halogens, namely, X F (X = Cl, Br), in the currently
3 3 3
investigated compounds is scarce, possibly because of the
reduced polarization associated with the fluorine atom itself.
However, these studies are still in the nascent stages and a
systematic exploration of interactions involving mixed halogens
in different molecular frameworks will provide relevant insights
aimed at a fundamental understanding of such interactions in the
solid state. In general, the studies conducted in this article bring
out the importance of halogen interactions as stabilizing motifs in
the solid state.
H
O
hydrogen bonds, intermolecular homo-halogen-
3 3 3
halogen contacts direct packing of molecules into noncen-
3 3 3
trosymmetric environments [2FA-4ClB, 2FA-4BrB, 2FA-4IB
have Cl Cl, Br Br, I I short contact that orient mole-
3 3 3
3 3 3
3 3 3
cules along the 21 screw axis which are orthogonal to the
direction along which strong N-H O hydrogen bonds are
3 3 3
formed, namely, the crystallographic a axis; 4FA-3ClB, 4FA-
3BrB, 4FA-4BrB all have F F contacts (Type I) in addition to
3 3 3
’ CONCLUSIONS
Cl Cl, Br Br, and I I intermolecular contact which
3 3 3
3 3 3
3 3 3
The synthesis and determination of the crystal and molecular
structure of a series of isomeric halogenated benzanilides
provide pointers toward the existence and relative importance
of strong H-bonds, weak intermolecular interactions, and halo-
gen contacts which play an instrumental role in dictating crystal
packing. Both electronic and steric factors play an important role
in determining the equilibrium conformation of the molecule,
and these are largely influenced by the crystal field in which such
molecules reside. Such differences due to changes in functional
group get manifested with concomitant changes in the nature of
interactions resulting in a different crystalline symmetry and
crystal packing. Although the initial formation of prenucleation
aggregates is guided by intermolecular interactions regarded as
an “instantaneous snapshot of crystallization”,33 it is the crystal-
line symmetry which decides the final crystal structure with a
minimization of the overall Gibbs free energy of formation of the
solid. Thus, the magnitude of energy changes involved in such
processes being small leads to the formation of polymorphs and
structures having Z0 > 1.
direct packing of molecules along the 21 screw axis. However,
the overall packing in these molecules is centrosymmetric; 3FB-
3ClA and 3FB-3BrA form Type II interhalogen contact along
the [101] crystallographic direction utilizing the n-glide plane as
the symmetry element, the overall packing being centrosym-
metric. A large number of benzanilides containing multiple
chlorine atoms on different positions of the two aromatic phenyl
rings have been synthesized, and their crystal and molecular
structures were determined.17 In addition to the well-character-
ized N-H O hydrogen bond, short contacts involving
3 3 3
different chlorine atoms have been observed in one such case,
that is, in 4-chloro-N-(2,6-dichlorophenyl)-benzamide. This
molecule crystallizes with four molecules in the asymmetric unit
and contains the homo-halogen Cl Cl short contact of
3 3 3
3.408(1) Å [17(x)]. These investigations performed on chlorine
containing benzanildes again point to the complexity associated
with prediction of crystal structures for closely related molecules
and the nature of the interactions, symmetry, and molecular
conformation which they adopt.
It is to be mentioned that F F contacts prefer Type I
From a supramolecular perspective, it is indeed of interest to gain
physical insights into the nature of both homo- and hetero-halogen
interactions in terms of a topological characterization of chemical
3 3 3
geometry, while the contacts involving heavier halogens, namely,
Cl Cl, Br Br, and I I prefer to have Type II geometry.
3 3 3
3 3 3
3 3 3
1594
dx.doi.org/10.1021/cg101544z |Cryst. Growth Des. 2011, 11, 1578–1596

Crystal Growth & Design
ARTICLE
Figure 21. 4FB-4BrA form a parallel infinite chain through N-H
O
3 3 3
and F F interactions which are interconnected through Br Br
3 3 3 3 3 3
short directional contact.
Table 19. List of Interacting Mixed Halogens along with the
Nature of Their Geometry
Figure 19. 4FB-3IA form (a) C-H F and C-I π parallel chains
3 3 3
3 3 3
(b) helix formation through alternate C-H F and C-I
π
3 3 3
3 3 3
interactions.
compound code
interacting halogens
type of interaction
2FA-3BrB
2FA-4ClB
2FA-4BrB
2FA-4IB
Br Br
II
II
II
II
II
II
II
II
I
3 3 3
Cl Cl
3 3 3
Br Br
3 3 3
I
I
3 3 3
3FA-4ClB
3FA-4BrB
4FA-2ClB
4FA-2BrB
4FA-3ClB
Cl Cl
3 3 3
Br Br
3 3 3
F
Cl
3 3 3
Br
F
3 3 3
F
F
3 3 3
Cl Cl
II
I
3 3 3
4FA-3BrB
4FA-4BrB
F
F
3 3 3
Br Br
II
I
3 3 3
F
F
3 3 3
Br Br
II
I
3 3 3
3FB-2ClA
3FB-3ClA
3FB-3ClA
4FB-2BrA
4FB-4ClA
F
F
3 3 3
Br
Br
Br
F
II
II
II
3 3 3
3 3 3
3 3 3
F
F
Cl Cl
I
I
I
3 3 3
4FB-4BrA
Br Br
3 3 3
F
F
3 3 3
’ AUTHOR INFORMATION
Corresponding Author
Figure 20. 4FB-4ClA forms a molecular conelike arrangement through
*To whom correspondence should be addressed. D.C. Tele-
phone: 0755-4092321. Fax: 07554092392. E-mail: dchopra@
iiserbhopal.ac.in. T.N.G.R.: Telephone 080-22932796; Fax: 080-
23601310; Email: ssctng@sscu.iisc.ernet.in.
C-H F, Cl Cl, and π π interactions.
3 3 3 3 3 3 3 3 3
systems which contain such contacts. The one-electron properties,
namely, the dipole moment, local stabilization energies, deformation
density, and electrostatic potential in the C-X/Y and X X/X
regions associated with such interactions is expected to provide a deeper
understanding of interactions involving halogens in the solid state.
Y
3 3 3
3 3 3
’ ACKNOWLEDGMENT
We thank DST, India, for the XRD facility at IISc, and S.K.N.
thanks CSIR for financial assistance. DC thanks DST-Fast Track
scheme for research grant.
’ ASSOCIATED CONTENT
S
Supporting Information. ORTEP diagrams, IR spectra,
b
experimental and simulated PXRD and NMR patterns for all the
synthesized compounds, selected dihedral angles, and crystallographic
information files (CIF). This material is available free of charge via the
Internet at http://pubs.acs.org.
’ REFERENCES
(1) (a) Purser, S.; Moore, P. R.; Swallow, S.; Gouverneur, V. Chem.
Soc. Rev. 2008, 37, 320. (b) Hagmann, W. K. J. Med. Chem. 2008,
1595
dx.doi.org/10.1021/cg101544z |Cryst. Growth Des. 2011, 11, 1578–1596

Crystal Growth & Design
ARTICLE
51, 4359. (c) Jeschke, P. Pest Manag. Sci. 2010, 66, 10. (d) Hagan, D. O’ J.
Fluor. Chem. 2010, 131, 1071.
(2) (a) Eustꢀaquio, A. S.; O’Hagan, D.; Moore, B. S. J. Nat. Prod.
2010, 73, 378.(b) Wakefield, B. Chem. Technol., 74. (c) Seebach, D.
Angew Chem. Int. Ed. Eng. 1990, 29, 1320.
J.; Fuess, H. Acta Crystallogr. 2007, E63, o3365. (d) Gowda, B. T.;
Tokarcík, M.; Kozísek, J.; Sowmya, B. P.; Fuess, H. Acta Crystallogr.
2008, E64, o462. (e) Gowda, B. T.; Sowmya, B. P.; Kozísek, J.; Tokarcík,
M.; Fuess, H. Acta Crystallogr. 2007, E63, o2906. (f) Gowda, B. T.; Foro,
S.; Sowmya, B. P.; Fuess, H. Acta Crystallogr. 2007, E63, o3789. (g)
Gowda, B. T.; Tokarcík, M.; Kozísek, J.; Sowmya, B. P.; Fuess, H. Acta
Crystallogr. 2008, E64, o540. (h) Gowda, B. T.; Tokarcík, M.; Kozísek, J.;
Sowmya, B. P.; Fuess, H. Acta Crystallogr. 2008, E64, o769. (i) Gowda,
B. T.; Foro, S.; Sowmya, B. P.; Fuess, H. Acta Crystallogr. 2008,
E64, o861. (j) Gowda, B. T.; Foro, S.; Sowmya, B. P.; Fuess, H. Acta
Crystallogr. 2008, E64, o949. (k) Gowda, B. T.; Tokarcík, M.; Kozísek, J.;
Sowmya, B. P.; Fuess, H. Acta Crystallogr. 2008, E64, o950. (l) Gowda,
B. T.; Foro, S.; Sowmya, B. P.; Fuess, H. Acta Crystallogr. 2008,
E64, o1243. (m) Gowda, B. T.; Foro, S.; Sowmya, B. P.; Fuess, H. Acta
Crystallogr. 2008, E64, o1294. (n) Gowda, B. T.; Foro, S.; Sowmya, B. P.;
Fuess, H. Acta Crystallogr. 2008, E64, o1300. (o) Gowda, B. T.; Foro, S.;
Sowmya, B. P.; Fuess, H. Acta Crystallogr. 2008, E64, o1342. (p) Gowda,
B. T.; Foro, S.; Sowmya, B. P.; Fuess, H. Acta Crystallogr. 2008,
E64, o1421. (q) Gowda, B. T.; Tokarcík, M.; Kozísek, J.; Sowmya,
B. P.; Fuess, H. Acta Crystallogr. 2008, E64, o1493. (r) Gowda, B. T.;
Tokarcík, M.; Kozísek, J.; Sowmya, B. P.; Fuess, H. Acta Crystallogr.
2008, E64, o1365. (s) Saeed, A.; Khera, R. A.; Gotoh, K.; Ishida, H. Acta
Crystallogr. 2008, E64, o1934. (t) Saeed, A.; Khera, R. A.; Abbas, N.;
Simpson, J.; Stanley, R. G. Acta Crystallogr. 2008, E64, o1976. (u)
Gowda, B. T.; Foro, S.; Sowmya, B. P.; Fuess, H. Acta Crystallogr. 2009,
E65, o444. (v) Saeed, A.; Khera, R. A.; Arfan, M.; Simpson, J.; Stanley,
R. G. Acta Crystallogr. 2009, E65, o802. (w) Saeed, A.; Khera, R. A.;
Ameen, S.; Simpson, J.; Stanley, R. G. Acta Crystallogr. 2009, E65, o201.
(x) Tokarcík, M.; Gowda, B. T.; Kozísek, J.; Sowmya, B. P.; Fuess, H.
Acta Crystallogr. 2009, E65, o1637. (y) Tan, Z.; Bing, Y.; Fang, S.; Kai, Z.;
Yan, Y. Acta Crystallogr. 2009, E65, o1757.
(3) O’Hagan, D. Chem. Soc. Rev. 2008, 37, 308.
(4) (a) Reichenb€acher, K.; S€uss, H. I.; Hulliger, J. Chem. Soc. Rev. 2005,
34, 22. (b) Schwarzer, A.; Seichter, W.; Weber, E.; Evans, H. S.; Losada, M.;
Hulliger, J. CrystEngComm 2004, 6, 567. (c) Rybalova, T. V.; Bagryanskaya,
I. Yu. J. Struct. Chem. 2009, 50, 741. (d) Thakur, T. S.; Kirchner, M. T.;
Bl€aser, D.; Boese, R.; Desiraju, G. R. CrystEngComm 2010, 12, 2079.
(5) (a) Choudhury, A. R.; Nagarajan, K.; Guru Row, T. N. Cryst.
Growth Des. 2004, 4, 47. (b) Choudhury, A. R.; Guru Row, T. N.
CrystEngComm. 2006, 8, 265.
(6) (a) Chopra, D.; Nagarajan, K.; Guru Row, T. N. J. Mol. Struct. 2008,
888, 70. (b) Chopra, D.; Guru Row, T. N. CrystEngComm 2008, 10, 54.
(7) (a) Jackson, S.; Degrado, W.; Dwivedi, A.; Parthasarathy, A.;
Higley, A.; Krywko, J.; Rockwell, A.; Markwalder, J.; Wells, G.; Wexler,
R.; Mousa, S.; Harlow, R. J. Am. Chem. Soc. 1994, 116, 3220. (b)
Capdeville, R.; Buchdunger, E.; Zimmermann, J.; Matter, A. Nat. Rev.
Drug Discovery 2002, 1, 493. (c) Makino, S.; Nakanishi, E.; Tsuji, T. Bull.
Korean Chem. Soc. 2003, 24, 389. (d) Zhichkin, P.; Kesicki, E.; Treiberg,
J.; Bourdon, L.; Ronsheim, M.; Ooi, H. C.; White, S.; Judkins, A.; Fairfax,
D. Org. Lett. 2007, 9, 1415.
(8) (a) Bondiwell, W. E.; Chan, J. A. U.S. Patent 6515027, 2003. (b)
Wickenden, A. O.; Gross, M. F.; McNaughton-Smith, G. A. U.S. Patent
6989398, 2006.
(9) (a) Chopra, D.; Nagarajan, K.; Guru Row, T. N. Cryst. Growth Des.
2005, 5, 1035. (b) Chopra, D.; Guru Row, T. N. Cryst. Growth Des. 2005,
5, 1679. (c) Chopra, D.; Guru Row, T. N. Cryst. Growth Des. 2008, 8, 848.
(d) Chopra, D.; Guru Row, T. N. Cryst. Growth Des. 2006, 6, 1267.
(10) (a) Chopra, D.; Thiruvenkatam, V.; Guru Row, T. N. Cryst.
Growth Des. 2006, 6, 843. (b) Chopra, D.; Thiruvenkatam, V.; Manju-
nath, S. G.; Guru Row, T. N. Cryst. Growth Des. 2007, 7, 868.
(11) Chopra, D.; Cameron, T. S.; Ferrara, J. D.; Guru Row, T. N.
J. Phys. Chem. A. 2006, 110, 10465.
(18) Grabowski, S. J.; Sadlej, A. J.; Sokalski, W. A.; Leszczynski J.
Chem. Phys. 2006, 327, 151.
(19) Serezhkin, V. V.; Prokaeva, M. A.; Pushkin, D. V.; Serezhkina,
L. B. Russ. J. Inorg. Chem. 2009, 54, 1251.
(20) Nayak, S. K.; Reddy, M. K.; Guru Row, T. N. Private Commu-
nication, 2010.
(12) Li, C.; Ren, S. F.; Hou, J. L.; Yi, H. P.; Zhu, S. Z.; Jiang, X. K.; Li,
Z. T. Angew. Chem., Int. Ed. Engl. 2005, 44, 5725.
(21) Chopra, D.; Guru Row, T. N. J. Mol. Struct. 2005, 733, 133.
(22) SMART (V 5.628), SAINT (V 6.45a), SADABS, XPREP,
SHELXTL; Bruker AXS Inc: Madison, WI, 2004.
(13) (a) Zhu, Y. Y.; Yi, H. P.; Li, C.; Jiang, X. K.; Li, Z. T. Cryst.
Growth Des. 2008, 8, 1294. (b) Zhu, Y. Y.; Jiang, L.; Li, Z. T.
CrystEngComm 2009, 11, 235.
(23) CrystAlis CCD and CrystAlis RED, Version 1.171.33.31; Oxford
(14) (a) Du, P.; Jiang, X. K.; Li, Z. T. Tet. Lett. 2009, 50, 316. (b)
Moorthy, J. N.; Natarajan, R.; Mal, P.; Venugopalan, P. J. Am. Chem. Soc.
2002, 124, 6530.
Difraction Ltd: Abingdon, Oxfordshire, England, 2009.
(24) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112.
(25) Farrugia,L.J.WinGX(V1.70.01).J. Appl. Crystallogr. 1999, 32, 837.
(26) (a) Farrugia, L. J. J. Appl. Crystallogr. 1997, 30, 565.(b) Burnett,
M. N.; Johnson, C. K. Report ORNL-6895; Oak Ridge National
Laboratory: Oak Ridge Tennessee, 1996.
(27) Macrae, C. F.; Bruno, I. J.; Chisholm, J. A.; Edgington, P. R.;
McCabe, P.; Pidcock, E.; Rodriguez-Monge, L.; Taylor, R.; Streek, J.; Wood,
P. A. J. Appl. Crystallogr. 2008, 41, 466; www.ccdc.cam.ac.uk/mercury.
(28) Nardelli, M. J. Appl. Crystallogr. 1995, 28, 569.
(15) (a) Pedireddi, V. R.; Reddy, S. D.; Goud, B. S.; Craig, D. C.; Rae,
A. D.; Desiraju, G. R. J. Chem. Soc. Perkin Trans. 2 1994, 2353. (b) Saraogi,
I.; Vijay, V. G.; Das, S.; Sekar, K.; Guru Row, T. N. Crystallogr. Eng. 2003,
6, 69. (c) Prasanna, M. D.; Guru Row, T. N. Crystallogr. Eng. 2000, 3, 135.
(16) (a) Hassel, O. Science 1970, 170, 497. (b) Ramasubbu, N.;
Parthasarathy, R.; Rust, M. P. J. Am. Chem. Soc. 1986, 108, 4308.
(c) Desiraju, G. R.; Parthasarathy, R. J. Am. Chem. Soc. 1989,
111, 8725. (d) Reddy, C. M.; Kirschner, M. T.; Gundakaram, R. C.;
Padmanabhan, K. A.; Desiraju, G. R. Chem.—Eur. J. 2006, 12, 2222. (e)
Samai, S.; Biradha, K. CrystEngComm 2009, 11, 482. (f) Nyburg, S. C.;
Wong-Ng, W. Inorg. Chem. 1979, 18, 2790. (g) Williams, D. E. J. Chem.
Phys. 1967, 47, 4680. (h) Bui, T. T. T.; Dahaoui, S.; Lecomte, C.;
Desiraju, G. R.; Espinosa, E. Angew. Chem., Int. Ed. 2009, 48, 3838. (i)
Desiraju, G. R.; Parthasarathy, R. J. Am. Chem. Soc. 1989, 111, 8725. (j)
Bosch, E.; Barnes, C. L. Cryst. Growth Des. 2002, 2, 299. (k) Saha, B. K.;
Nangia, A.; Nicoud, J. F. Cryst. Growth Des. 2006, 6, 1278. (l) Pigge,
F. C.; Vangala, V. R.; Swenson, D. C. Chem. Commun. 2006, 2123. (m)
Anthony, A.; Desiraju, G. R.; Kuduva, S. S.; Madhavi, N. N. L.; Nangia,
A.; Thaimattam, R.; Thalladi, V. R. Cryst. Eng. 1998, 1, 1. (n) Jetti,
R. K. R.; Xue, F.; Mak, T. C. W.; Nangia, A. Crystallogr. Eng. 1999, 2, 215.
(17) (a) Gowda, B. T.; Sowmya, B. P.; Kozísek, J.; Tokarcík, M.;
Fuess, H. Acta Crystallogr. 2007, E63, o2906. (b) Gowda, B. T.; Sowmya,
B. P.; Tokarcík, M.; Kozísek, J.; Fuess, H. Acta Crystallogr. 2007,
E63, o3326. (c) Gowda, B. T.; Sowmya, B. P.; Tokarcík, M.; Kozísek,
(29) Spek, A. L. Acta Crystallogr. 1990, A46, c34.
(30) (a) Kashino, S.; Ito, K.; Haisa, M. Bull. Chem. Soc. Jpn. 1979,
52, 365. (b) Bowes, K. F.; Glidewell, C.; Low, J. N.; Skakle, J. M. S.;
Wardell, J. S. Acta Crystallogr. 2003, C59, o1.
(31) Chopra, D.; Guru Row, T. N. CrystEngComm 2008, 10, 54.
(32) K0alm0an, A. Acta Crystallogr. 2005, B61, 536.
(33) Das, D.; Banerjee, R.; Mondal, R.; Howard, J. A. K.; Boese, R.;
Desiraju, G. R. Chem. Commun. 2006, 555.
(34) Manjunatha Reddy, G. N.; Vasantha Kumar, M. V.; Guru Row,
T. N.; Suryaprakash, N. Phys. Chem. Chem. Phys. 2010, 12, 13232.
(35) Dance, I. New J. Chem. 2003, 27, 22.
(36) Pogliani, L. New. J. Chem. 2003, 27, 919.
(37) Pedireddi, V. R.; Reddy, D. S.; Goud, B. S.; Craig, D. C.; Rae,
A. D.; Desiraju, G. R. J. Chem. Soc. Perkin Trans. 2 1994, 2353.
(38) Saha, B. K.; Nangia, A.; Nicoud, J.-F. Cryst. Growth. Des. 2006,
6, 1278.
1596
dx.doi.org/10.1021/cg101544z |Cryst. Growth Des. 2011, 11, 1578–1596