Analysis of Cl...Cl and C-H...Cl intermolecular interactions involving chlorine in substituted 2-chloroquinoline derivatives

Article abstract of DOI:10.1007/s12039-010-0056-1

Six crystal structures of substituted 2-chloroquinoline derivatives have been analysed to evaluate the role of Cl atom as a self recognizing unit resulting in the formation of Cl...Cl and C-H...Cl interactions to generate supramolecular assembly in the solid state. The features of Type I and Type II geometries associated with Cl...Cl interactions have been analysed to show directional preferences leading to differences in the packing motifs in these crystal structures. C-H...Cl interactions are generated exclusively in structures depicting Type II Cl...Cl interaction have been observed in these structures. Indian Academy of Sciences.

Full text of DOI:10.1007/s12039-010-0056-1

J. Chem. Sci., Vol. 122, No. 5, September 2010, pp. 677–685. © Indian Academy of Sciences.
Analysis of Cl…Cl and C–H…Cl intermolecular interactions involving
chlorine in substituted 2-chloroquinoline derivatives
a
VENKATESHA R HATHWAR , S MOHANA ROOPAN , R SUBASHINI ,
b
b
b a,
F NAWAZ KHAN and T N GURU ROW *
a
Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012
b
Organic Chemistry Division, School of Advanced Sciences, Vellore Institute of Technology University,
Vellore 632 014
e-mail: ssctng@sscu.iisc.ernet.in
Abstract. Six crystal structures of substituted 2-chloroquinoline derivatives have been analysed to
evaluate the role of Cl atom as a self recognizing unit resulting in the formation of Cl…Cl and C–H…Cl
interactions to generate supramolecular assembly in the solid state. The features of Type I and Type II
geometries associated with Cl…Cl interactions have been analysed to show directional preferences lead-
ing to differences in the packing motifs in these crystal structures. C–H…Cl interactions are generated
exclusively in structures depicting Type II Cl…Cl interaction have been observed in these structures.
Keywords. Intermolecular interactions; halogen…halogen contacts; C–H…Cl hydrogen bonds;
supramolecular assemblies.
6
tries. In case of F, it is generally observed that
1. Introduction
C–H…F interactions prevail over F…F interac-
7
tions. However, this feature is disputed both from
The presence of halogen atom, in particular chlorine
in place of methyl group on simple aromatic com-
pounds has been shown to significantly alter the
theory and more recently with large number of ex-
perimental observations showing preferences to the
8
1
crystal structure. Even though both chlorine and
formation of F…F interactions. It has become obvi-
methyl groups are of similar size and occupy about
the same volume, dichloro substitution on aromatic
molecules produce crystal structures with one of the
ously clear that halogen…halogen interaction could
very well be utilized as a design element in crystal
engineering. Recent studies on the experimental
charge density analysis on the nature of Cl…Cl
interaction has demonstrated that Type II contacts
may be understood as a interaction between electro-
philic and nucleophilic region between adjacent
halogen atom, a feature which unambiguously sup-
2
axis being 4 Å. Recent ab initio calculations show
that halogen…halogen contacts are controlled by
electrostatic forces and indeed display directional
3
preferences. In a recent article, concerning over-
crowding of halogens as in the case of hexachloro-
benzene, both chemical and geometrical models
4
appear to dictate halogen…halogen interactions. In
general C–X1…X2–C contacts are classified into two
types with θ1 = C–X1…X2 and θ2 = X1…X2–C and
d = X1⋅⋅⋅X2 distance as Type I (cis or trans geome-
5
try) and Type II (L geometry) (scheme 1).
If the angles are nearly similar, θ1 ≅ θ2 the geome-
try is associated with Type I whereas θ1 ≅ 180º and
θ2 ≅ 90º represents Type II geometry. Desiraju et al
have demonstrated that Type II contacts dominate in
case of X = I whereas Type I dominate in case of
X = Cl with X = Br displaying both types of geome-
Scheme 1. Schematic representation of Type I (cis and
trans geometries) and Type II (L geometry) halogen…
halogen contacts.
*For correspondence
677

678
Venkatesha R Hathwar et al
9
port attractive nature of Cl…Cl interactions. We mers was extracted with dichloromethane. The pure
have recently shown by in situ cryo-crystallization required isomer product QN1 was obtained through
technique that the structure of 2-chloro aniline (low column chromatography, ethyl acetate/petroleum
melting organic liquid) is stabilized via X3 synthon ether was used as the eluant. Routine IR, NMR and
10
resulting in a helical motif along the 31 axis.
Mass analysis confirmed the formation of compound
In this article, we have determined the crystal QN1. Single crystals of suitable quality for single
structure of six 2-chloroquinoline derivatives (scheme crystal X-ray diffraction were grown by solvent
2) and have analysed the directional preference in evaporation technique from 1 : 1 mixture of ethyl
Cl…Cl interaction in terms of crystal packing and acetate/hexane solvents.
have analysed the propensity of the formation of
C–H…Cl contacts in both Type I and Type II 2.1b Compound QN2: 2,4-dichloro 6-methyl-
geometries. All the six structures are heterocyclic quinoline: 4-Methylaniline (1 mmol), malonic acid
derivatives constituting an interesting class of com- (1 mmol) and 10 ml of dry POCl3 were taken in a
pounds with synthetic versatility and effective RB flask and the resulting mixture was heated at
biological activities. Indeed, quinoline and their 453 K for 1 h. Entire experimental procedure was
derivatives have remarkable pharmacological acti- same as in QN1.
11
vities and widely used as antiallergic, antimalarial
12
13
antibacterial, antiproliferative, anticancer and 2.1c Compound QN3: 2-Chloro-(quinolin-3-yl)
14
15
16
antiparasitic compounds.
methanol: 2-Chloro-3-formylquinoline (1 mmol),
sodium borohydride (1 mmol) and catalytic amount
of montmorillonite K-10 were taken in an open ves-
sel and the resulting mixture was irradiated at
500 W in a domestic microwave oven for 4–5 min.
Ethylacetate was poured into the reaction mixture
and the catalyst was filtered off. The filtrate was
subjected to column chromatography and ethyl ace-
tate/petroleum ether was used as the eluant. IR,
NMR and Mass analysis confirmed the formation of
compound QN3. Single crystals of suitable quality
for single crystal X-ray diffraction were grown by
solvent evaporation technique from chloroform.
2. Experimental
2.1 Synthesis
2.1a Compound QN1: 2,4-dichloro 5-methyl qui-
noline: 3-Methylaniline (1 mmol), malonic acid
(1 mmol) and 10 ml of dry POCl3 were taken in a
RB flask and the resulting mixture was heated at
453 K for 1 h. The reaction mixture after completion
of reaction (monitored by TLC) was poured into the
crushed ice and residue containing mixture of iso-
2.1d Compound QN4: 2-Chloro-(7-methylquinolin-
3-yl) methanol: 2-Chloro-7-methylquinoline-3-carbal-
dehyde (1 mmol), sodium borohydride (1 mmol) and
catalytic amount of montmorillonite K-10 were
taken in an open vessel and the resulting mixture
was irradiated at 500 W in a domestic microwave
oven for 4–5 min. The experimental procedure was
similar to compound QN1.
2.1e Compound QN5: 2-Chloro-3-(chloromethyl)-
6-methylquinoline: 2 mL of thionyl chloride was
added to 2-chloro-(6-methylquinolin-3-yl) methanol
(0⋅5 mmol) and refluxed at 349 K for 30 min. The
progress of the reaction was monitored by thin layer
chromatography (TLC). After the completion of reac-
tion, the reaction mixture was cooled and transferred
into the crushed ice. The precipitate was filtered and
dried in air. The compound was purified by column
chromatography using petroleum ether as the eluant.
IR, NMR and Mass analysis confirmed the forma-
Scheme 2. (i) Compound QN1 where R2 = Cl, R3 =
Methyl (CH3); R1 = R4 = R5 = R6 = H. (ii) Compound
QN2 where R2 = Cl, R4 = Methyl (CH3); R1 = R3 = R5 =
R6 = H. (iii) Compound QN3 where R1 = Hydroxymethyl
(CH2OH); R1 = R2 = R3 = R4 = R5 = H. (iv) Compound
QN4 where R1 = Hydroxymethyl (CH2OH) and R5 =
Methyl (CH3); R2 = R3 = R4 = R6 = H. (v) Compound
QN5 where R1 = Chloromethyl (CH2Cl) and R4 = Methyl
(CH3), R2 = R3 = R5 = R6 = H. (vi) Compound QN6
where R1 = Chloromethyl (CH2Cl) and R6 = Methyl
(CH3), R2 = R3 = R4 = R5 = H.

Analysis of Cl…Cl and C–H…Cl intermolecular interactions involving chlorine
679
Table 1. Crystallographic and refinement details for the structures.
Compound
QN1
QN2
QN3
Crystal size (mm)
CCDC number
0⋅28 × 0⋅21 × 0⋅12
756830
0⋅26 × 0⋅21 × 0⋅17
731569
0⋅24 × 0⋅18 × 0⋅15
705547
Molecular Formula
Formula weight
–1
C10H7N1Cl2
C10H7N1Cl2
C10H8N1O1Cl1
(g mol )
212⋅07
212⋅07
193⋅62
Temperature (K)
Wavelength (Å)
295(2)
295(2)
295(2)
0⋅71073
Multi-scan
0⋅650
0⋅71073
Multi-scan
0⋅629
0⋅71073
Multi-scan
0⋅398
Absorption correction
–1
μ (mm )
Crystal system
Space group
a (Å)
Monoclinic
P21/c
Triclinic
P-1
Triclinic
P-1
6⋅8668(2)
12⋅9735(3)
10⋅4447(2)
90
7⋅1525(2)
11⋅5551(3)
11⋅9852(3)
90⋅168(2)
106⋅152(3)
91⋅090(2)
951⋅25(5)
4
7⋅1181(5)
7⋅3518(5)
9⋅1811(6)
92⋅803(4)
106⋅624(3)
109⋅900(4)
427⋅14(5)
2
b (Å)
c (Å)
α (°)
β (°)
98⋅476(3)
90
γ (°)
3
Volume (Å )
920⋅33(4)
4
Z
–3
Density (g cm )
1⋅531
1⋅481
1⋅505
F(000)
432
432
200
θ (min, max
hmin,max
kmin,max
lmin,max
)
2⋅52, 26
(–8, 8)
3⋅00, 25⋅49
(–8, 8)
2⋅35, 25⋅50
(–8, 8)
(–16 15)
(–12,12)
9527
(–13, 13)
(–14, 14)
18705
(–8, 8)
(–11, 10)
6896
No. of measured reflections
No. of unique reflections
No. of parameters
R(int)
1810
3542
1578
119
237
119
0⋅0321
0⋅0310
0⋅0206
R_all, R_obs
0⋅0516, 0⋅0328
0⋅0850, 0⋅0802
–0⋅244, 0⋅213
1⋅032
0⋅0531, 0⋅0376
0⋅1082, 0⋅1038
–0⋅227, 0⋅209
1⋅067
0⋅0317, 0⋅0287
0⋅0792, 0⋅0775
–0⋅268, 0⋅163
1⋅119
wR2_all, wR2_obs
–3
Δρmin,max (e Å )
G.o.F
Compound
QN4
QN5
QN6
Crystal size (mm)
CCDC number
0⋅40 × 0⋅15 × 0⋅10
725752
0⋅35 × 0⋅31 × 0⋅21
731573
0⋅21 × 0⋅16 × 0⋅12
746771
C11H9N1Cl2
226⋅09
Molecular formula
–1
Formula weight (g mol )
C11H10N1O1Cl1
207⋅65
C11H9N1Cl2
226⋅09
Temperature (K)
Wavelength (Å)
295(2)
295(2)
295(2)
0⋅71073
Multi-scan
0⋅356
0⋅71073
Multi-scan
0⋅588
0⋅71073
Multi-scan
0⋅578
Absorption correction
–1
μ (mm )
Crystal system
Space group
a (Å)
Monoclinic
P21/c
Triclinic
P-1
Monoclinic
P21/c
19⋅978(2)
7⋅2814(12)
13⋅7772(13)
90
6⋅6003(8)
7⋅6250(10)
11⋅1333(14)
84⋅018(2)
74⋅507(2)
71⋅764(2)
512⋅70(11)
2
15⋅1752(3)
4⋅6020(1)
14⋅9781(3)
90
b (Å)
c (Å)
α (°)
β (°)
104⋅593(10)
90
94⋅357(2)
90
γ (°)
3
Volume (Å )
1939⋅5(4)
8
1042⋅99(4)
4
Z
–3
Density (g cm )
1⋅422
1⋅465
1⋅440
F(000)
864
232
464
θ (min, max
)
3⋅06, 25⋅50
1⋅90, 25⋅50
3⋅13, 26⋅00
Contd…

680
Venkatesha R Hathwar et al
Table 1. (Contd…)
Compound
QN4
(–23, 24)
QN5
QN6
hmin,max
(–7, 7)
(–18, 18)
(–5, 5)
kmin,max
(–8, 8)
(–9, 9)
lmin,max
(–16, 16)
19752
(–13, 13)
5078
(–18, 18)
9881
No. of measured reflections
No. of unique reflections
No. of parameters
R(int)
3600
1895
2051
257
128
128
0⋅0632
0⋅0168
0⋅0192
R_all, R_obs
wR2_all, wR2_obs
–3
0⋅0851, 0⋅0428
0⋅1089, 0⋅1005
–0⋅199, 0⋅230
0⋅906
0⋅0391, 0⋅0346
0⋅0941, 0⋅0916
–0⋅302, 0⋅195
1⋅042
0⋅0406, 0⋅0312
0⋅0974, 0⋅0942
–0⋅205, 0⋅177
1⋅136
Δρmin,max (eÅ )
G.o.F
Table 2. Intermolecular Cl…Cl contacts in studied six compounds.
∠C–X1…X2°
∠X1…X2–C°
(θ2)
Compound
C–X1…X2–C
X1…X2 Å
(θ1)
Symmetry operation
QN1
QN2
C1–Cl1…Cl1–C1
3⋅545(2)
3⋅662(1)
3⋅813(1)
3⋅661(2)
3⋅546(1)
3⋅613(1)
3⋅614(2)
3⋅575(2)
144⋅0
168⋅0
156⋅8
150⋅4
142⋅2
155⋅6
167⋅5
132⋅0
144⋅0
107⋅2
109⋅1
150⋅4
122⋅5
155⋅6
100⋅1
132⋅0
–x + 1, –y + 2, –z – 1
x, y – 1, z + 1
C3A–Cl2A…Cl1B–C1B
C3B–Cl1A…Cl2B–C1A
C1–Cl1…Cl1–C1
x, y, z + 1
QN3
QN4
QN5
–x + 1, –y + 2, –z + 1
x – 1, –y + 1/2, z + 1/2
–x + 2, –y, –z
C1B–Cl1B…Cl1A–C1A
C10–Cl2…Cl2…C10
C1–Cl1…Cl2–C10
C1–Cl1…Cl1–C1
–x + 1, –y + 1, –z
–x + 1, –y + 1, –z
QN6
C10–Cl2…Cl1–C1
3⋅538(1)
167⋅8
104⋅9
–x + 1, –y + 2, –z + 1
20
tion of compound QN5. Single crystals of suitable (version 1.63.04a). The molecular diagrams were
21
quality for single crystal X-ray diffraction were grown generated using POV-ray (version 3.6)
and
by solvent evaporation technique from chloroform. the packing diagrams were generated using
22
CAMERON. Geometrical calculations were done
23
24
2.1f Compound QN6: 2-Chloro-3-(chloromethyl)- using PARST95 and PLATON. The positions of
8-methylquinoline: To 2-chloro-(8-methylquinolin- all hydrogen atoms were fixed geometrically and
3-yl) methanol (0⋅5 mmol), 2 mL of thionyl chloride refined isotropically using the riding hydrogen atom
was added and refluxed at 349 K for 30 min. The model. The details of the data collection and refine-
workup procedure was similar to compound QN5.
ment are given in table 1, Cl…Cl contacts and other
intermolecular interactions are listed in tables 2 and
3, respectively.
2.2 X-ray diffraction
The single crystal X-ray diffraction data of all crys-
3. Result and discussion
tals were collected on an Oxford Xcalibur (Mova)
17
diffractometer with Eos CCD detector. The X-ray 3.1 Structure of 2,4-dichloro 5-methylquinoline
generator was operated at 50 kV and 1mA using (QN1)
Enhanced MoKα radiation. Data were collected with
The substitution of methyl moiety to 2-chloro-
quinoline structure at position R3 resulted in com-
pound QN1 (scheme 2), which crystallizes in the
space group P21/c with Z = 4. Figure 1a gives the
ORTEP diagram of QN1 with ellipsoids drawn at
50% probability. Intermolecular Cl…Cl contacts of
Type I trans geometry (figure 1b, table 2) along with
ω scan width of 1°. The data reduction, an empirical
absorption correction and space group determination
were done using CrysAlisPro RED of Oxford Dif-
17
fraction. The crystal structures were solved by
18
direct method using either SIR92 or SHELXS
19
and refined by full matrix least-squares method using
19
SHELXL97, present in the program suite WinGx

Analysis of Cl…Cl and C–H…Cl intermolecular interactions involving chlorine
Table 3. Intermolecular interactions in studied six compounds.
681
Crystal
D–H…A
D–H/Å
H…A/Å
D…A/Å
∠D–H…A/°
Symmetry
QN1
QN2
QN3
C6–H6…N1
0⋅930
0⋅960
0⋅820
0⋅930
0⋅970
2⋅610
2⋅956
2⋅220
2⋅685
2⋅790
3⋅530(1)
3⋅719(2)
2⋅956(2)
3⋅146(2)
3⋅689(1)
169⋅0
137⋅0
149⋅0
136⋅0
154⋅0
x, –y + 1/2 + 1, z + 1/2
–x, –y + 1, –z
C10A–H10C…Cl2B
O1–H1O…N1
x – 1, y, z
C4–H4…O1
–x, –y + 1, –z + 2
–x + 1, –y + 2, –z
C10–H10A…Cg(2)
QN4
O1A–H1OA…N1A
O1B–H1OB…N1B
C11A–H11A…O1A
C4B–H4B…O1B
0⋅820
0⋅820
0⋅960
0⋅930
2⋅160
2⋅220
2⋅650
2⋅689
2⋅921(2)
2⋅978(3)
3⋅420(3)
3⋅454(3)
155⋅0
153⋅0
137⋅0
140⋅0
x, –y + 1/2, z + 1/2
x, –y + 1/2 + 1, z + 1/2 – 1
–x + 1, y – 1/2, z + 1/2 + 1
–x + 2, –y + 1, –z + 1
QN5
QN6
C10–H10A...Cl1
C10–H10B…Cl2
C10–H10A…Cg(1)
0⋅970
0⋅970
0⋅970
2⋅868
2⋅942
2⋅970
3⋅747(2)
3⋅899(2)
3⋅563(2)
151⋅0
169⋅0
121⋅0
x + 1, y, z
–x + 1, y + 1/2, –z + 1/2 + 1
x, y – 1, z
In compound QN3, Cg(2) is centroid of C4/C9 ring whereas in compound QN6, Cg(1) is centroid of N1–C1–C2–C3–
C9–C8 ring.
Figure 1. (a) ORTEP of compound QN1 drawn with 50% ellipsoidal probability. (b) Packing diagram of com-
pound QN1 depicting intermolecular Cl…Cl contacts and C–H…N hydrogen bonds.
an intermolecular C–H…N hydrogen bond (table 3) space group with two independent molecules in the
hold the molecules together in the crystal lattice. asymmetric unit. The ORTEP diagram of QN2 (fig-
This results in a parallel arrangement of molecules ure 2a) shows the two independent molecules and
generation π…π stacking interactions with a separa- the dihedral angle between the least squares planes
tion distance of 3⋅614(1)–3⋅724(2) Å between aro- of these molecules is 15⋅88(2)°. Cl…Cl intermolecu-
matic rings leading to further stabilization of the lar interactions develop between Cl1A and Cl2B
crystal structure.
(figure 2b, table 2) connecting the two independent
molecules in a two-dimensional motif through the
entire crystal. An additional short Cl…Cl contact
(slightly larger than the van der Waal radii sum,
table 2) develops as a consequence. Indeed this con-
3.2 Structure of 2,4-dichloro 6-methylquinoline
(QN2)
Compound QN2 is an isomer of compound QN1 tact appears as a surrogate to the C–H…Cl intera-
with the methyl group now at position R4 (scheme ction (figure 2b). π…π stacking interactions of
2). The cell parameters are almost identical to QN1 3⋅578(1)–3⋅768(2) Å between aromatic rings stabi-
and the compound crystallizes in a triclinic P-1 lize the packing in the lattice. It is noteworthy

682
Venkatesha R Hathwar et al
that the nitrogen atom does not participate in an in- figure 4a), which crystallizes in the space group
termolecular interaction like in QN1.
P21/c with Z = 8 and resulting in two independent
molecules at asymmetric unit. The dihedral angle
between the least squares plane of two independent
molecules in asymmetric unit is 6⋅17(2)°. Cl…Cl
contacts have Type II geometry, however θ1 and θ2
deviate significantly from the ideal values of Type II
contact (figure 4b, table 2). O–H…N and C–H…O
hydrogen bonds add further stability to the packing
(figure 4b, table 3). π…π aromatic stacking interac-
3.3 Structure of 2-Chloro-(quinolin-3-yl) methanol
(QN3)
The substitution of hydroxymethyl group at the posi-
tion R1 of 2-chloroquinoline gives compound QN3
(scheme 2) which crystallizes in the space group P-1
with Z = 2 (figure 3a). Type I Cl…Cl contacts with
trans geometry (figure 3b) hold the molecules
together along with strong intermolecular O–H…N
and C–H…O hydrogen bonds (figure 3b, table 3).
C–H…π (figure 3b, table 3) interactions provide fur-
ther stability by holding molecular dimers across the
centre of inversion. π…π aromatic stacking interac-
tions of 3⋅674(1)–3⋅774(1) Å between aromatic rings
exist as in the previous cases.
3.4 Structure of 2-Chloro-(7-methylquinolin-3-yl)
methanol (QN4)
The substitution of an additional methyl group at
position R3 to QN3 gives compound QN4 (scheme 2,
Figure 3. (a) ORTEP of compound QN3 drawn with
50% ellipsoidal probability. (b) Packing diagram of com-
pound QN3 depicting intermolecular Cl…Cl contacts,
O–H…N hydrogen bonds along with C–H…O and
C-H…π [Cg(2)] interactions which generate molecular
dimers.
Figure 2. (a) ORTEP of compound QN2 drawn with
50% ellipsoidal probability. (b) Packing diagram of com-
pound QN2 depicting intermolecular Cl…Cl contacts and
C–H…Cl hydrogen bonds.

Analysis of Cl…Cl and C–H…Cl intermolecular interactions involving chlorine
683
3.6 Structure of 2-chloro-3-(chloromethyl)-8-
methylquinoline (QN6)
tions of 3⋅842(1)–3⋅887(2) Å between aromatic rings
stabilise the packing.
Compound QN6 is an isomer of compound QN5.
(scheme 2). The compound (figure 6a) crystallizes
in the space group P21/c with Z = 4. Cl…Cl interac-
tions with Type II geometry are generated by
involving chlorine atoms Cl1 and Cl2, resulted in a
molecular dimer formation across the centre of
inversion (figure 6b, table 2). C–H…Cl hydrogen
bonds generate a ‘sinusoidal’ molecular chain (fig-
ure 6b). C–H…π intermolecular interactions gener-
ate a 1D molecular chain as in QN5 while one π…π
stacking interaction of 3⋅614(1) Å is conserved in
the crystal packing.
3.5 2-Chloro-3-(chloromethyl)-6-methylquinoline
(QN5)
The substitution of chloromethyl group at position
R1 and methyl group at R4 respectively to 2-
chloroquinoline resulted in compound QN5 (scheme
2, figure 5a), which crystallises in the space group
P-1 with Z = 2. The crystal structure is stabilized by
Cl…Cl interactions and C–H…Cl halogen bonds
only. Cl1 and Cl2 generate ‘bifurcated’ Cl…Cl short
contacts resulting in a ‘sawtooth’ type supramolecu-
lar network in the crystal lattice (figure 5b). Both
Type I and Type II Cl…Cl intermolecular interac-
tions coexist in this structure. The C–H…Cl hydro-
gen bond generates a one dimensional molecular
chain along the crystallographic ‘a’ axis (figure 5b,
table 3). π…π aromatic stacking interactions in the
range of 3⋅718(1)–3⋅764(2) Å between aromatic
rings provide further stability as in the previous
cases.
4. Conclusion
The above studies bring out an interesting feature in
substituted 2-chloroquinolines. Type II Cl…Cl
interactions generate C–H…Cl interactions in the
supramolecular assembly in the crystal lattice. This
Figure 5. (a) ORTEP of compound QN5 drawn with
50% ellipsoidal probability. (b) Packing diagram of com-
pound QN5 showing ‘bifurcated’ Cl…Cl short contacts
generating a ‘saw tooth’ type network. C–H…Cl hydro-
gen bonds form a molecular chain along ‘a’ axis.
Figure 4. (a) ORTEP of compound QN4 drawn
with 50% ellipsoidal probability. (b) Packing
diagram of compound QN4 depicting intermolecular
Cl…Cl interactions, O–H…N and C-H…O hydrogen
bonds.

684
Venkatesha R Hathwar et al
ited with the Cambridge Crystallographic Data Center,
12 Union Road, Cambridge, CB2, 1E-Z,UK (Fax:
+44-1223-336-033; email: deposit@ccdc.sam.ac.uk).
The depository numbers are given in the tables.
Acknowledgements
We thank Department of Science and Technology
(DST), FIST level II for providing the XCaliber
Mova Oxford diffraction machine at SSCU, Indian
Institute of Science (IISc), Bangalore. FNK thanks
DST for Fast Track proposal funding.
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