Role of weak interactions in the structure of 3-(α,α′- dibromomethyl)benzyl 1-4 benzotriazole (DBT)

Article abstract of DOI:10.1080/744818942

3-(α,α′-Dibromomethyl)benzyl 1-4 benzotriazole, C ₁₄H₁₁Br₂N₃, F.W,= 381.08, tridinic, P1, a= 8.411(1)A, b=9.008(1)A, c=9.714(1) A, α=97.74(1)°, β=103.11(1)°, ;γ=101.62(1)°, V=689.4(1)A³, Z=2, D_cal=1.836Mgm^-3, μ-7.364mm^-1, λ(CuKα)=1.5418A, final R1 and wR2 are 0.0538 and 0.1383, respectively. The title compound is a precursor for the macroligand stilbenobenzo-triazolophane. Unusual short bond length in the benzotriazole ring suggests the delocalization effect on the bonding. Intermolecular C-H...π, C-H... Br, and some face-to-face π-π interactions play a role in stabilizing the delocalized form. The molecules in the unit cell are stabilized by C-H... N type of interactions in addition to van der Waals forces.

Full text of DOI:10.1080/744818942

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ROLE OF WEAK INTERACTIONS
IN THE STRUCTURE OF 3-(α,α′-
DIBROMOMETHYL)BENZYL 1-4
BENZOTRIAZOLE (DBT)
S. M. Malathy Sony a , M. Kuppayee a , M. N.
Ponnuswamy a , V. Murali b & P. Rajakumar b
a Department of Crystallography and Biophysics,
University of Madras, Guindy Campus, Chennai-600
025, India
b Department of Organic Chemistry, University of
Madras, Guindy Campus, Chennai-600 025, India
Published online: 02 Feb 2011.
To cite this article: S. M. Malathy Sony , M. Kuppayee , M. N. Ponnuswamy , V. Murali
& P. Rajakumar (2003) ROLE OF WEAK INTERACTIONS IN THE STRUCTURE OF 3-(α,α′-
DIBROMOMETHYL)BENZYL 1-4 BENZOTRIAZOLE (DBT), Molecular Crystals and Liquid
Crystals, 403:1, 15-22, DOI: 10.1080/744818942
To link to this article: http://dx.doi.org/10.1080/744818942
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Mol. Cryst. Liq. Cryst., Vol. 403, pp. 15–22, 2003
Copyright # Taylor & Francis Inc.
ISSN: 1542-1406 print/1563-5287 online
DOI: 10.1080/15421400390234020
ROLE OF WEAK INTERACTIONS IN THE
STRUCTURE OF 3-(a,a0-DIBROMOMETHYL)BENZYL
1-4 BENZOTRIAZOLE (DBT){
S. M. Malathy Sony, M. Kuppayee, and M. N. Ponnuswamy*
Department of Crystallography and Biophysics, University of
Madras, Guindy Campus, Chennai-600 025, India
V. Murali and P. Rajakumar
Department of Organic Chemistry, University of Madras,
Guindy Campus, Chennai-600 025, India
3-(a,a0-Dibromomethyl)benzyl 1-4 benzotriazole, C14H11Br2N3, F:W: ¼ 381.08,
triclinic, P1, a ¼ 8.411(1)A, b ¼ 9.008(1)A, c ¼ 9.714(1) A, a ¼ 97.74(1)ꢀ,
˚
˚
˚
¯
b ¼ 103.11(1)ꢀ, g ¼ 101.62(1)ꢀ, V ¼ 689.4(1)A , Z ¼ 2, Dcal ¼ 1.836 Mgmꢁ3
,
3
˚
m ¼ 7.364 mmꢁ1, lðCuKaÞ ¼ 1.5418 A, final R1 and wR2 are 0.0538 and 0.1383,
˚
respectively.
The title compound is a precursor for the macroligand stilbenobenzo-
triazolophane. Unusual short bond length in the benzotriazole ring suggests the
delocalization effect on the bonding. Intermolecular C-H . . . p, C-H . . . Br, and
some face-to-face p-p interactions play a role in stabilizing the delocalized form.
The molecules in the unit cell are stabilized by C-H . . . N type of interactions in
addition to van der Waals forces.
Keywords: p-interactions; benzotriazole; delocalization; crystal structure; hydrogen bond
INTRODUCTION
Triazoles are synthetic intermediates derived from hydrazine hydrate.
Amino 1,2,4-triazoles are used for the synthesis of active ingredients for
phytosanitary, pharmaceutical, and veterinary products and photographic
products.
Benzotriazole and its derivatives comprise an important class of corro-
sion inhibitors, typically used as trace additives in industrial chemical
Received 3 December 2002; accepted 5 May 2003.
{The CDB Reference Number: DBT - CCDC 200294.
*Corresponding author. E-Mail: mnpsy@hotmail.com
15

16
S. M. Malathy Sony et al.
mixtures such as coolants, deicers, surface coatings, cutting fluids, and
hydraulic fluids. Recent studies have shown that benzotriazole derivatives
are a major component of aircraft deicing fluids (ADFs) responsible for
toxicity to bacteria [1].
1H-benzotriazole derivatives containing thiazolin, thiazolidin, thiadia-
zole, and oxadiazole moieties showed anti-inflammatory activity and also
demonstrate minimum ulcerogenic activity [2]. Hydroxybenzoyl-benzo-
triazoles activated potassium channels showed vasorelaxing properties [3].
Amino-benzotriazole is an inhibitor of Cytochrome P-450 (Cyt P-450) [4]
and some piperazinyl-benzotriazoles bind to the serotonin 5-HT1A receptor
and exhibit good analgesic, antihypertensive activity and adrenergic a1
antagonism [5]. Hydroazepin-3-yl-benzotriazole-5-carboxamides deriva-
tives showed potent antiemetic activity and gastroprokinetic activity [6].
The benzotriazole under study is a precursor for the macroligand stil-
benobenzotriazolophane whose structural study will provide an idea for the
chemists to obtain the required final product.
EXPERIMENTAL
Preparation of the Compound
m-Xylene was added to three equivalent moles of N-bromo succinimide in
CCl4. This mixture was refluxed for 12 h, and periodically benzyl peroxide
was added, which was then cooled. The precipitate of tribromide was
purified and reacted with benzotriazole in the presence of 25% of sodium
hydroxide and methyl cyanide at room temperature for 2 days. The crude
product was extracted with methylene chloride. The organic layer was
dried and recrystallized from methylene chloride/hexane (Scheme I).
X-ray Data Collection, Structure Solution and Refinement
Transparent rectangular plate-shaped crystal of dimension 0:25ꢂ
0:30 ꢂ 0:15 mm was chosen for the intensity data collection on an Enraf-
Nonius CAD-4 diffractometer with graphite monochromated CuKa
˚
(l ¼ 1:5418 A) radiation [7]. Accurate unit cell parameters were obtained
from 25 reflections in the range 15 ꢃ y ꢃ 25ꢀ from least-squares refine-
ment. The intensities were measured to a maximum 2y of 144.68ꢀ by o=2y
scan mode. Three standard reflections monitored for every hundred
reflections for intensity check showed little or no decay (<1%) throughout
the data collection. Out of 2553 ðRint ¼ 0:0493Þ independent reflections
collected, 2383 reflections with I ꢄ 2sðIÞ were used for structure analysis.
The intensities were corrected for Lorentz and polarization effects using

Structure of a Benzotriazole Derivative
17
SCHEME 1 Synthetic pathway of the title compound.
TABLE 1 Crystal Data
Parameter
DBT
C14H11Br2N3
381.08
Empirical formula
Formula weight
˚
Wavelength (A)
1.54178
ꢀ
Crystal system, space group
Unit cell dimensions
Triclinic, P1
˚
a(A)
8.411(1)
9.008(1)
9.714(1)
97.74(1)
103.11(1)
101.61(1)
689.43(13)
2, 1.836
˚
b(A)
˚
c(A)
aðꢀÞ
bðꢀÞ
gðꢀÞ
3
˚
Volume (A )
Z, Calculated densityðMg=m3Þ
Absorption coefficientðmmꢁ1
Þ
7.364
372
F(000)
Theta range for data collectionðꢀÞ
4.76 to 72.34
ꢁ10 ꢃ h ꢃ 10
0 ꢃ k ꢃ 8
ꢁ11 ꢃ 1 ꢃ 11
Index ranges
Reflections collected/unique
Completeness to ꢀ ¼ 72:34
Data/restraints/parameters
Goodness-of-fit on F2
2553/2383 ½RðintÞ ¼ 0:0493ꢅ
87.3%
2383/0/173
1.071
Final R indices ½I > 2ꢁðIÞꢅ
R indices (all data)
Extinction coefficient
R1 ¼ 0:0538, wR2 ¼ 0:1383
R1 ¼ 0:0706, wR2 ¼ 0:1702
0.0250(17)
ꢁ3
˚
Largest diff. peak and hole (e. A
)
0.742 and ꢁ0.980

18
S. M. Malathy Sony et al.
the data reduction program XCAD4PC [8]. Cylindrical-type absorption
correction was carried using C. W. Dwiggins Jr.’s [9] method, and the
minimum and maximum transmission values (Tmin and Tmax) are 0.1971
and 0.2847, respectively.
The structure was solved by direct methods using the program
SHELXS97 [10]. The structure was refined on F2 by full-matrix least-
squares procedures using the program SHELXL97 [11]. The nonhydrogen
atoms were refined anisotropically, and all the hydrogens were fixed as
riding model over their heavier atoms. The final cycle of refinement con-
verged to R1 ¼ 0:0538 and wR1 ¼ 0:1383 for the observed reflections. The
maximum and minimum heights in the final difference Fourier map were
3
˚
found to be 0.742 and ꢁ0.980e/A , respectively. The geometrical calcula-
tions and the figures were done by using the programs PLATON [12] and
ZORTEP [13], respectively.
RESULTS AND DISCUSSION
The crystal data and the other relevant parameters are given in Table 1.
The atomic coordinates with their equivalent isotropic displacement fac-
tors for nonhydrogen atoms are presented in Table 2 and the perspective
view of the molecule is shown in Figure 1.
The bond lengths and bond angles are comparable with the values
˚
reported in the literature [14], except for the bond C12-C13 [1.296(9) A],
which possesses more of a double bond character. This may be due to the
delocalization of electrons in the bonding [15], which is attributed by some
weak intermolecular interactions made by the benzotriazole ring (Figure
2). The benzotriazole ring makes face-to-face p-p intermolecular interac-
tion with the symmetry-related benzotriazole ring ð2 ꢁ x; ꢁy; ꢁzÞ with
˚
centroid-centroid distance of 4.0882A and the dihedral angle between the
planes, a ¼ 0:00ꢀ. The benzyl ring also interacts face to face with its
˚
symmetry-related ð2 ꢁ x; 1 ꢁ y; 1 ꢁ zÞ molecule with Cg ꢁ Cg ¼ 3:6647A
(Cg ! centroid of the p-system) and a ¼ 0:03ꢀ [16–18]. In addition to
these interactions, the molecule also has C-H . . . p intermolecular interac-
tions where the benzyl p-system (Cg2) interacts with C13 & C14 atoms
(Table 3). Analysis of the short intermolecular contacts implied that the
bromine atom Br2 makes a weak bifurcated C-H . . . Br interaction with C12
˚
½x; 1 þ y; 1 þ zꢅ and C15 ½x; 1 þ y; zꢅ atoms (H12 . . . Br2 ¼ 3:042 A and
˚
H15 . . . Br2 ¼ 3:037A) (Figure 3) [18]. All these weak interactions help in
stabilizing the delocalized form.
The benzotriazole ring is planar and oriented to the benzyl ring at an
angle of 83:7ð2Þꢀ. This geometry also creates a favorable edge-to-face p-p
intramolecular interaction between these rings with the Cg ꢁ Cg distance

Structure of a Benzotriazole Derivative
19
TABLE 2 Atomic Coordinates ðꢂ104Þ and Equivalent Isotropic Displacement
2
3
˚
Parameters (A ꢂ10 ) Involving Nonhydrogen Atoms
Atom
x
y
z
*U(eq)
Br1
Br2
C1
4184(1)
7234(1)
8949(7)
8283(7)
7335(7)
7055(8)
7762(9)
8687(9)
10089(9)
9603(6)
10388(8)
9720(10)
8537(9)
7297(13)
6184(12)
6098(10)
7159(9)
8340(7)
6629(8)
5648(1)
8303(1)
3240(8)
4337(7)
5131(7)
4812(8)
3707(9)
2929(8)
2447(10)
2136(6)
3053(7)
2560(8)
1313(8)
348(11)
ꢁ801(12)
ꢁ1109(10)
ꢁ209(9)
1017(7)
6306(7)
1658(1)
3658(1)
2977(7)
2378(6)
3061(6)
4358(7)
4975(8)
4278(8)
2307(9)
769(7)
71(1)
79(1)
48(2)
41(1)
39(1)
51(2)
56(2)
57(2)
68(2)
52(1)
71(2)
79(2)
54(2)
78(2)
83(3)
89(3)
66(2)
47(2)
47(2)
C2
C3
C4
C5
C6
C7
N8
N9
ꢁ11(9)
N10
C11
C12
C13
C14
C15
C16
C17
ꢁ1346(10)
ꢁ1515(8)
ꢁ2741(10)
ꢁ2591(12)
ꢁ1240(15)
7(10)
ꢁ163(8)
2367(7)
*U(eq) ¼ (1/3) Si Sj Uij ai*aj* ai.aj.
FIGURE 1 ZORTEP plot of the molecule with 30% probability displacement
ellipsoids and with atomic numbering scheme.

20
S. M. Malathy Sony et al.
FIGURE 2 Possible delocalized form of the benzotriazole ring in the molecule.
ꢀ
ꢀ
˚
˚
of 4.6150 A ða ¼ 83:73 Þ and 5.4738 A ða ¼ 83:37 Þ from the triazole and
the benzene ring of benzotriazole ring to the benzyl ring, respectively. The
benzyl ring is planar and the maximum deviation observed for the atoms is
TABLE 3 Possible Nonbonded Interactions
<(DHA)ꢀ
˚
d(D-H)A
˚
˚
d(D . . . A)A
d(H . . . A)A
C2-H2
0.93
C2 . . . N9
3.44(1)
H2 . . . N9
2.838
C2-H2 . . . N9 (1)
123.4(4)
C2-H2
0.93
C2 . . . N9
3.69(1)
H2 . . . N9
2.888
C2-H2 . . . N9 (2)
145.4(4)
C2-H2
0.93
C2 . . . N10
3.36(1)
H2 . . . N10
2.782
C2-H2 . . . N10 (2)
121.0(4)
C17-H17
0.98
C17 . . . N9
3.77(1)
H17 . . . N9
2.851
C17-H17 . . . N9 (2)
157.3(4)
C17-H17
0.98
C17 . . . N10
3.44(1)
H17 . . . N10
2.709
C17-H17 . . . N10 (2)
131.9(4)
C13-H13
0.93
C13 . . . Cg2
3.920
H13 . . . Cg2
3.260
C13-H13 . . . Cg2 (3)
129.5
C14-H14
0.93
C14 . . . Cg2
3.926
H14 . . . Cg2
3.270
C14-H14 . . . Cg2 (3)
128.9
Equivalent positions: (1) xþ1,þy,þz; (2) ꢁxþ1,ꢁyþ1,ꢁz; (3) 1ꢁx,ꢁy,ꢁz. Cg2, Centroid of
the benzyl ring.

Structure of a Benzotriazole Derivative
21
FIGURE 3 Diagram illustrating all possible interactions of the molecule.
FIGURE 4 Packing of the molecules viewed down c axis.

22
S. M. Malathy Sony et al.
˚
0.008(8) A for C5. The packing of the molecules viewed down the c-axis is
shown in Figure 4. The bifurcated C-H . . . Br intermolecular interaction
forms an interaction network along the z-direction and the C17-H17 . . . N10
hydrogen bond forms a network along y direction. These two inter-
molecular networks arrange the molecules in a two-dimensional linear
polymer fashion in the crystal lattice. The molecules in the crystal are
stabilized by C-H . . . N type of intermolecular interactions, in addition to
van der Waals forces (Table 3).
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