Bis(2-benzyl-1H-benzimidazole-N3)dichlorozinc(II).

Article abstract of DOI:10.1107/S0108270100014876

In the title compound, [ZnCl2(C14H12N2)2], the environment around the Zn atom is distorted tetrahedral formed by two Cl atoms and two tertiary N atoms of the 2-benzyl-1H-benzimidazole ligands. N-H...Cl intermolecular hydrogen bonds link the molecules into

Full text of DOI:10.1107/S0108270100014876

metal-organic compounds
pyrimidine)2 [102.09 (9)±117.54 (4)ꢀ; Salas et al., 1994] but the
coordination around the Zn atom in another complex, which
also contains the ZnCl2N2 unit, namely ZnCl2(purine)2 (Laity
& Taylor, 1995), is severely distorted compared with the title
complex, with angles ranging from 99.9 (1) to 113.7 (1)ꢀ.
Acta Crystallographica Section C
Crystal Structure
Communications
ISSN 0108-2701
Bis(2-benzyl-1H-benzimidazole-N3)-
dichorozinc(II)
Fengli Bei,a Fangfang Jian,a Xujie Yang,a Lude Lu,a Xin
Wang,a Ibrahim Abdul Razak,b S. Shanmuga Sundara Rajb
and Hoong-Kun Funb*
aMaterials Chemistry Laboratory, Nanjing University of Science and Technology,
Nanjing 210094, People's Republic of China, and bX-ray Crystallography Unit,
School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
Correspondence e-mail: hkfun@usm.my
Ê
The average ZnÐCl distance of 2.261 (1) A is longer than
the average corresponding distances reported for related
metal complexes with distorted ZnN2Cl2 tetrahedral envir-
Ê
onments, cf. 2.224 (1) A in ZnCl2(5,7-dimethyl-1,2,4-tria-
Ê
zolo[1,5-a]pyrimidine)2 (Salas et al., 1994), 2.212 (4) A in
ZnCl2(2,9-dimethyl-1,10-phenanthroline) (Preston & Ken-
Received 25 August 2000
Accepted 23 October 2000
Ê
nard, 1969), 2.226 (2) A in ZnCl2(purine)2 (Laity & Taylor,
Ê
1995) and 2.209 (3) A in ZnCl2(4-vinylpyridine)2 (Steffen &
Ê
Palenik, 1977), but comparable to the value of 2.255 (1) A in
ZnCl2[1-(5,6-dimethylbenzimidazolyl)-3-benzimidazolyl-2-
thiapropane] (Matthews et al., 1998).
In the title compound, [ZnCl2(C14H12N2)2], the environment
around the Zn atom is distorted tetrahedral formed by two Cl
atoms and two tertiary N atoms of the 2-benzyl-1H-benz-
imidazole ligands. NÐHÁ Á ÁCl intermolecular hydrogen bonds
link the molecules into in®nite chains in the [101] direction.
Comment
Benzimidazole is an interesting heterocyclic ring because it is
present in various naturally occurring drugs, such as
omeprazole, astemizole and emedastine difumarate (Sakai et
al., 1989). The ef®cacy of substituted benzimidazoles in the
treatment of parasitic infections is well known (Brown et al.,
1961; Preston, 1974; Sarkar et al., 1984). Benzimidazole-
substituted moieties are established pharmacophores in
parasitic chemotherapy. Bis(2-benzimidazoles) and some
substituted bis(benzimidazol-2-yl)alkanes have attracted
much interest because of their wide-ranging antiviral activity
(Tidwell et al., 1993) and also because of the coordination
chemistry of azoles acting as ligands in transition metal
compounds. Such compounds are increasingly being studied in
the context of modelling biological systems (Pujar et al., 1988;
Bouwman et al., 1990). Zinc is a relatively abundant element in
biological organisms and plays an essential role in a large
number of enzymatic reactions (Liljas et al., 1972). ZnII, being
a d10 ion, provides few spectroscopic signatures for the
monitoring of structure. The structure of the zinc binding site
can only be elucidated by X-ray crystallography.
Figure 1
The structure of the title compound showing 50% probability displace-
ment ellipsoids and the atom-numbering scheme.
Ê
The average ZnÐN bond distance of 2.042 (3) A is
Ê
comparable to reported average values, e.g. 2.039 (3) A in
ZnCl2(5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine)2 (Salas et
Ê
al., 1994), 2.05 (1) A in ZnCl2(1-methyltetrazole)2 (Baenziger
Ê
& Schultz, 1971), 2.059 (3) A in ZnCl2(1-methylcytosine)2
Ê
(Beauchamp, 1984) and 2.027 (3) A in ZnCl2[1-(5,6-dimethyl-
benzimidazolyl)-3-benzimidazolyl-2-thiapropane] (Matthews
Ê
et al., 1998), but longer than the average value of 2.007 (4) A
in Zn0.99Cu0.01Cl2(1,2-dimethylimidazole)2 (Bharadwaj et al.,
1991).
In the title compound, (I), the molecule possesses near C2
symmetry and the symmetry axis lies parallel to the b axis. The
Zn atom is coordinated tetrahedrally by two Cl anions and
two 2-benzyl-1H-benzimidazole ligands, i.e. ZnCl2N2. The
ZnCl2N2 tetrahedron is slightly distorted, with angles ranging
from 103.32 (7) to 116.67 (7)ꢀ. The range of the tetrahedral
angles is comparable with the corresponding values in the
reported complex ZnCl2(5,7-dimethyl-1,2,4-triazolo[1,5-a]-
ꢁ
Acta Cryst. (2001). C57, 45±46
# 2001 International Union of Crystallography
Printed in Great Britain ± all rights reserved 45

metal-organic compounds
Re®nement
The dihedral angles between the benzimidazole moieties
(involving N1/N2 and N3/N4) and the phenyl rings (C9±C14
and C23±C28) are 83.0 (2) and 79.4 (2)ꢀ, respectively. The
mean planes of the two benzimidazole moieties form a dihe-
dral angle of 69.7 (1)ꢀ, while the dihedral angle between the
phenyl rings is 1.2 (2)ꢀ.
Re®nement on F2
R[F2 > 2ꢄ(F2)] = 0.051
wR(F2) = 0.133
S = 0.93
6226 re¯ections
316 parameters
H-atom parameters constrained
w = 1/[ꢄ2(Fo2) + (0.0592P)2]
where P = (Fo2 + 2Fc2)/3
(Á/ꢄ)max < 0.001
3
Ê
Áꢅmax = 0.74 e A
3
Ê
1.51 e A
Áꢅmin
=
In the crystal, the N2 and N4 atoms of the benzimidazole
moieties are involved in NÐHÁ Á ÁCl intermolecular hydrogen
bonds with the Cl atoms (Table 2). These intermolecular
hydrogen bonds link the molecules into in®nite one-dimen-
sional chains in the [101] direction.
After checking their presence in the difference map, the positions
of all H atoms were calculated geometrically and allowed to ride on
Ê
their attached atoms (NÐH = 0.86 A and CÐH = 0.93±0.97 A). The
Ê
Ê
highest peak and deepest hole are located 0.91 and 0.82 A, respec-
tively, from the Zn atom. Examination of the structure with
PLATON (Spek, 1990) showed that there were solvent-accessible
3
voids of 34 A in the crystal lattice, but there was no evidence of
Ê
diffuse solvent in these holes.
Experimental
Data collection: SMART (Siemens, 1996); cell re®nement: SAINT
(Siemens, 1996); data reduction: SAINT; program(s) used to solve
structure: SHELXTL (Sheldrick, 1997); program(s) used to re®ne
structure: SHELXTL; molecular graphics: SHELXTL; software used
to prepare material for publication: SHELXTL and PLATON (Spek,
1990).
Solid 2-benzyl-1H-benzimidazole was dissolved in EtOH/H2O. Zinc
dichloride was then added at 343±353 K with stirring and the
resulting solution was re¯uxed for 4±5 h and then cooled. The red
solution obtained was ®ltered and left to evaporate. After one day,
red solids had separated out and were recrystallized from EtOH/H2O.
Single crystals suitable for X-ray analysis were obtained by slow
evaporation from an EtOH solution at room temperature.
The authors would like to thank the Malaysian Government
and Universiti Sains Malaysia for research grant R & D No.
305/PFIZIK/610942. SSSR thanks the Universiti Sains
Malaysia for a Visiting Postdoctoral Fellowship.
Crystal data
3
[ZnCl2(C14H12N2)2]
Mr = 552.78
Monoclinic, P21/n
Dx = 1.438 Mg m
Mo Kꢁ radiation
Cell parameters from 8192
re¯ections
Ê
a = 11.8623 (2) A
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: LN1109). Services for accessing these data are
described at the back of the journal.
ꢂ = 1.92±28.32ꢀ
ꢃ = 1.196 mm
T = 293 (2) K
Ê
b = 16.3674 (1) A
1
Ê
c = 14.1767 (2) A
ꢀ = 111.943 (1)ꢀ
V = 2553.08 (6) A
Z = 4
3
Ê
Slab, red
0.28 Â 0.24 Â 0.20 mm
References
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Data collection
Siemens SMART CCD area-
detector diffractometer
! scans
Absorption correction: empirical
(SADABS; Sheldrick, 1996)
Tmin = 0.731, Tmax = 0.796
17 665 measured re¯ections
6226 independent re¯ections
3898 re¯ections with I > 2ꢄ(I)
Rint = 0.073
ꢂ
max = 28.28ꢀ
h = 7 ! 15
k = 21 ! 21
l = 18 ! 18
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Table 1
Selected geometric parameters (A, ).
ꢀ
Ê
Zn1ÐN1
Zn1ÐN3
2.039 (2)
2.044 (2)
Zn1ÐCl1
Zn1ÐCl2
2.2575 (8)
2.2626 (8)
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N1ÐZn1ÐN3
N1ÐZn1ÐCl1
N3ÐZn1ÐCl1
108.54 (9)
103.32 (7)
116.67 (7)
N1ÐZn1ÐCl2
N3ÐZn1ÐCl2
Cl1ÐZn1ÐCl2
115.44 (7)
104.47 (6)
108.84 (3)
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È
Sheldrick, G. M. (1996). SADABS. University of Gottingen, Germany.
Table 2
Hydrogen-bonding geometry (A, ).
Sheldrick, G. M. (1997). SHELXTL Software Reference Manual. Version 5.1.
Bruker AXS Inc., Madison, Wisconsin, USA.
ꢀ
Ê
Siemens (1996). SMART and SAINT. Siemens Analytical X-ray Instruments
Inc., Madison, Wisconsin, USA.
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C. C. & Hall, J. E. (1993). Antimicrob. Agents Chemother. 37, 1713±1716.
DÐHÁ Á ÁA
DÐH
HÁ Á ÁA
DÁ Á ÁA
DÐHÁ Á ÁA
N2ÐH2AÁ Á ÁCl2i
0.86
0.86
2.46
2.55
3.240 (3)
3.314 (3)
152
148
N4ÐH4AÁ Á ÁCl1ii
Symmetry codes: (i) ‡ x; 12 y; 21 ‡ z; (ii) x
;
y; z
1
2
1
2
1
2
1
.
2
ꢁ
46 Fengli Bei et al. [ZnCl2(C14H12N2)2]
Acta Cryst. (2001). C57, 45±46