organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
C5ÐN4 in both molecules (Table 1). All the formal single
endocyclic bonds are considerably shorter than those usually
found for normal single bonds, but the formal double bonds
are somewhat longer than normal double bonds (International
Tables for Crystallography, 1992, Vol. C, pp. 707±791). This
suggests that there is some conjugation in the tetrazole rings of
(I); however, signi®cant differences in the endocyclic bond
lengths show that there is still considerable localization of
charge within them.
The bond distances and angles in the phenyl-ring fragments
of (I) are consistent with those observed previously. The rings
Ê
are nearly planar to within 0.009 (1) and 0.008 (1) A for
molecules A and B, respectively.
ISSN 0108-2701
4-Nitro-2-(1H-tetrazol-1-yl)phenol
Alexander S. Lyakhov,* Pavel N. Gaponik, Sergei V.
Voitekhovich, Ludmila S. Ivashkevich and Alexander A.
Kulak
Institute of Physico-Chemical Problems, Belarusian State University,
Leningradskaya Str. 14, Minsk 220050, Belarus
The phenyl and tetrazole rings are not coplanar in either
molecule, the dihedral angles between them being 30.2 (1) and
7.0 (1)ꢁ in molecules A and B, respectively. To compare these
Correspondence e-mail: lyakhov@fhp.bsu.unibel.by
Received 17 April 2001
Accepted 17 July 2001
There are two symmetry-independent molecules in the unit
cell of the title compound, C7H5N5O3. The tetrazole and
phenyl rings are essentially planar and are not coplanar in
either molecule [dihedral angles 30.2 (1) and 7.0 (1)ꢁ]. In the
structure, four molecules are connected by OÐHÁ Á ÁN bridges,
forming four-membered molecular aggregates which are
linked together by a complex three-dimensional hydrogen-
bond network.
Comment
Monosubstituted 1-aryltetrazoles have attracted considerable
theoretical and experimental interest. On the one hand, they
are used as valuable intermediates in the synthesis of aryl-
cyanamides (Gaponik et al., 1990) and different nitrogen-
containing heterocycles (Voitekhovich et al., 2001), while on
the other hand, they have attracted interest as models for
investigation of the interaction between tetrazole and phenyl
rings. Only the structures of 1-phenyltetrazole (Matsunaga et
al., 1999) and 1-(2,4,6-trimethylphenyl)tetrazole (Lyakhov et
al., 2000) have been described previously. In this paper, we
present the crystal structure of a new compound, namely
4-nitro-2-(1H-tetrazol-1-yl)phenol, (I) (Fig. 1). There are two
symmetry-independent molecules in the structure, denoted A
and B hereafter.
Figure 1
ORTEP-3 drawing (Farrugia, 1997) of molecule A of (I) with the atom-
numbering scheme; for molecule B, substitute the A suf®xes with B.
Displacement ellipsoids are drawn at the 50% probability level and H
atoms are shown as spheres of arbitrary radii.
values with that of a free molecule of (I), an ab initio calcu-
lation of a single molecule in the 6±311G** basis set was
carried out using the GAMESS program (Schmidt et al., 1993).
Geometry optimization with respect to all variables results in a
dihedral angle between the phenyl and tetrazole rings of 39.6ꢁ.
It should be noted that in the crystal of 1-phenyltetrazole, the
dihedral angle between the rings is 11.8 (1)ꢁ (Matsunaga et al.,
1999), whereas an angle of 38.6ꢁ was obtained from an MP2/6±
31G* calculation for a free molecule of 1-phenyltetrazole
(Matsunaga et al., 1999). The introduction of an ortho-
substituent on the phenyl ring must result in increased steric
hindrance compared with 1-phenyltetrazole and, as a result,
the dihedral angle between the rings increases. Such a situa-
tion is also seen in the crystal structure of 1-(2,4,6-trimethyl-
phenyl)tetrazole, where the dihedral angle is 69.07 (9)ꢁ
(Lyakhov et al., 2000), and also in molecule A of (I). In the case
of molecule B of (I), a rather small dihedral angle is found.
Taking these results into account, it may be presumed that the
decrease in the dihedral angle in the crystal is due to mole-
cular packing. In the structure of (I), this effect is larger for
molecule B than for molecule A.
The tetrazole rings of molecules A and B have very similar
Ê
geometries and are planar to within 0.004 (2) and 0.005 (2) A,
respectively. The endocyclic angles are in the ranges 105.5 (1)±
111.1 (1) and 106.1 (1)±110.6 (1)ꢁ for molecules A and B,
respectively. The N1ÐN2 and N3ÐN4 bonds are similar and
longer than N2ÐN3, while the C5ÐN1 bond is longer than
ꢀ
1204 # 2001 International Union of Crystallography
Printed in Great Britain ± all rights reserved
Acta Cryst. (2001). C57, 1204±1206
Lyakhov
