2,6-Dimethy1-1,4-benzoquinone 4-monooxime

Article abstract of DOI:10.1107/S0108270105005500

Molecules of the title compound, C₈H₉NO₂, are linked into sheets by a combination of C - H...N, O - H...N and O-H...O hydrogen bonds and C-H...π interactions. The hydrogen bonds are arranged as described by the graph-set r

Full text of DOI:10.1107/S0108270105005500

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
the phenolic form, while the 5-methoxy and 5-dimethylamino
derivatives are found in solvent-dependent equilibrium with
their corresponding quinonoid forms. In general, it was
established that quinonoid forms are favoured in polar
solvents, while phenolic forms are favoured in non-polar
solvents (Kr zÏ an et al., 2000). Generally, o-nitrosophenols exist
in the quinone monooxime form, while p-nitrosophenols exist
in the nitrosophenol form (Abilgaard et al., 1998; Kr zÏ an et al.,
ISSN 0108-2701
2
4
,6-Dimethyl-1,4-benzoquinone
-monooxime
2
000; Kr zÏ an & Mavri, 2002). As we could not ®nd in the
literature any example of a solid-state compound in the
quinone monooxime form, an X-ray structure determination
of the title compound, (I), was carried out and the results are
presented here.
a
a
Mustafa Odaba Ës o gÆ lu, CË i gÆ dem Albayrak and Orhan
b
B uÈ y uÈ kg uÈ ng oÈ r *
a
Department of Chemistry, Ondokuz Mayõs University, TR-55139 Samsun, Turkey,
b
and Department of Physics, Ondokuz Mayõs University, TR-55139 Samsun, Turkey
Correspondence e-mail: orhanb@omu.edu.tr
Received 4 January 2005
Accepted 18 February 2005
Online 11 March 2005
Molecules of the title compound, C H NO , are linked into
9
8
2
sheets by a combination of CÐHÁ Á ÁN, OÐHÁ Á ÁN and OÐ
HÁ Á ÁO hydrogen bonds and CÐHÁ Á Áꢀ interactions. The
hydrogen bonds are arranged as described by the graph-set
2
2
3
3
ring notations R (7) and R (5), and a C8 chain motif. There
are two planar symmetry-independent molecules in the
ꢀ
asymmetric unit, with a dihedral angle of 19.24 (5) between
their least-squares mean planes.
Comment
H-atom transfer in a hydrogen bond is an elementary process
present in many systems of biological interest. Recently, many
experimental and computational studies have addressed H-
atom dynamics in hydrogen bonds (Yan et al., 2001; Mavri &
Grdadolnik, 2001a,b; Rospenk et al., 2001; Do sÏ l c i et al., 2001).
In addition, the quinone monooximate (nitroso) complexes of
transition metals are of interest in respect of their structure,
reactivity and possible application as starting reagents in the
synthesis of a wide variety of organic compounds (Kasumov et
al., 2000). Quinone monooxime compounds are an example of
systems possessing both intra- and intermolecular hydrogen
bonds (Kr zÏ an & Mavri, 2002). They are key reagents in the
production of azo dyes. Since they are good complexing
agents, they have found a place in many analytical, synthetic
and other applications (Carugo et al., 1991; Shipmen et al.,
2,6-Dimethyl-1,4-benzoquinone monooxime, (I), was
synthesized according to the reaction mechanism in the
scheme. In the structure of (I), there are two symmetry-
independent molecules in the asymmetric unit (Fig. 1).
Selected bond distances and angles (I) are listed in Table 1.
Compound (I) possesses normal geometrical parameters and,
1
955; Castellani & Millini, 1984; Verdoorn et al., 1994). In
solution, quinone monooximes generally exist as a mixture of
quinone monooxime±nitrosophenol and ±nitrosonaphthol
tautomers (see scheme).
The nitroso±oxime tautomeric equilibrium has been
extensively studied by spectroscopic methods, including UV,
IR and NMR techniques (Fischer et al., 1965; Enchev et al.,
1
999; Ivanova & Enchev, 2001). The latter is a particularly
Figure 1
powerful method for studying the structure and dynamics of
such hydrogen-bonded systems (Abilgaard et al., 1998). In the
classic study on nitrosophenols (Burawoy et al., 1955), it was
shown that, in solution, 2-nitrosophenol exists exclusively in
Aview of the two independent molecules of (I), with the atom-numbering
scheme. Displacement ellipsoids are drawn at the 50% probability level
and H atoms are shown as small spheres of arbitrary radii. Dashed lines
indicate the intermolecular hydrogen bonds.
o240 # 2005 International Union of Crystallography
DOI: 10.1107/S0108270105005500
Acta Cryst. (2005). C61, o240±o242

organic compounds
as expected, is essentially planar [for the non-H atoms, the
largest r.m.s. deviations from the best least-squares plane are
Experimental
A mixture of 2,6-dimethylaniline (1.51 g, 10 mmol), water (50 ml) and
concentrated hydrochloric acid (2.5 ml, 30 mmol) was heated with
stirring until a clear solution was obtained. This solution was cooled
to 273±278 K and a solution of sodium nitrite (0.96 g, 14 mmol) in
water was added dropwise. The resulting mixture was stirred for
30 min at 278±288 K. The precipitated product was crystallized from
acetonitrile to obtain crystals of 2,6-dimethyl-1,4-benzoquinone
monooxime, (I) (m.p. 444±446 K).
Ê Ê
0.008 (2) A for the C1±C6 ring and 0.024 (2) A for the C9±
C14 ring].
�
The present determination reveals that compound (I) exists
as the quinone±oxime tautomer in the solid state. This is
evident from the relative contraction of the C1ÐO1, C4ÐN1,
C2ÐC3 and C5ÐC6 bonds, and the relative elongation of the
C1ÐC2, C3ÐC4, C4ÐC5, C1ÐC6 and N1ÐO2 bonds. A
similar pattern of bond contractions and elongations was also
observed for the C9±C14 ring (Table 1). It should be noted
here that the tautomers of o-benzoquinone monoxime have
been investigated by Carugo et al. (1991). The NÐO bond
distances in the o-benzoquinone monoxime and its nitroso-
Crystal data
C
H
8 9
NO
2
Mo Kꢁ radiation
Cell parameters from 7762
re¯ections
M
r
= 151.16
Orthorhombic, Pbca
Ê
ꢀ
a = 7.2505 (7) A
b = 16.3379 (10) AÊ
c = 26.4894 (17) A
Ê
V = 3137.9 (4) A
ꢂ = 1.5±25.9
�
1
Ê
ꢃ = 0.09 mm
T = 296 K
Tetragonal prism, red
phenol tautomer are reported to be 1.378 and 1.200 A,
Ê
3
Ê
respectively. The corresponding values in (I) are 1.362 (3) A
Ê
for N1ÐO2 and 1.377 (2) A for N2ÐO4, showing that both
molecules are in the quinone monooxime form. The orienta-
tions of the methyl groups are thought to be determined by the
steric effects of the adjacent carbonyl groups. All the non-H
atoms in each molecule lie in the same plane, as shown by the
Z = 16
D
0.30 Â 0.17 Â 0.09 mm
�
3
x
= 1.280 Mg m
Data collection
Stoe IPDS-2 diffractometer
! scans
20 873 measured re¯ections
Rint = 0.062
ꢀ
ꢂmax = 26.1
Ê
h = � 8 ! 8
r.m.s. deviations of 0.003 (2) and 0.003 (2) A from the corre-
sponding least-squares mean planes.
3
1
089 independent re¯ections
718 re¯ections with I > 2ꢄ(I)
k = � 17 ! 20
l = � 32 ! 32
Further examination of non-bonded contacts also reveals
four intermolecular hydrogen bonds (Table 2). Hence, as
shown in Fig. 1, asymmetric units of (I) are linked through
C11ÐH11Á Á ÁN1 and O2ÐH2Á Á ÁN2 hydrogen bonds, and the
Re®nement
2
2
2
o
2
Re®nement on F
2
w = 1/[ꢄ (F
where P = (F
(Á/ꢄ)max < 0.001
) + (0.0913P) ]
2
2 2
R[F > 2ꢄ(F )] = 0.048
wR(F ) = 0.143
o c
+ 2F )/3
2
Ê
� 3
Áꢅmax = 0.31 e A
dihedral angle between the C1±C6 and C9±C14 rings is
S = 0.87
3089 re¯ections
198 parameters
H-atom parameters constrained
Áꢅmin = � 0.27 e AÊ
�
3
ꢀ
1
9.24 (5) . The arrangement of the C11ÐH11Á Á ÁN1 and O2Ð
Extinction correction: SHELXL97
(Sheldrick, 1997)
Extinction coef®cient: 0.0052 (11)
H2Á Á ÁN2 hydrogen bonds can be described by the graph-set
2
2
notation R (7). Other hydrogen bonds are arranged as
3
described by R (5) and a C8 chain motif in the bc plane (Fig. 2)
3
(
Bernstein et al., 1995).
Stacking of the quinoid rings in (I) shows a Cg1Á Á ÁCg1
Table 1
i
Selected geometric parameters ( AÊ , ).
ꢀ
Ê
separation of 3.6375 (14) A [Cg1 is the centroid of the C1±C6
ring; symmetry code: (i) + x, y, � z].
1
2
1
2
C1ÐO1
C1ÐC6
C1ÐC2
C2ÐC3
C3ÐC4
C4ÐN1
C4ÐC5
C5ÐC6
C9ÐO3
1.238 (2)
1.466 (3)
1.469 (3)
1.331 (3)
1.430 (3)
1.320 (3)
1.440 (3)
1.343 (3)
1.231 (3)
C9ÐC10
C9ÐC14
C10ÐC11
C11ÐC12
C12ÐN2
C12ÐC13
C13ÐC14
N1ÐO2
1.470 (3)
1.480 (3)
1.336 (3)
1.448 (3)
1.297 (2)
1.443 (3)
1.338 (3)
1.362 (3)
1.377 (2)
N2ÐO4
C4ÐN1ÐO2
110.74 (18)
C12ÐN2ÐO4
112.90 (16)
C3ÐC4ÐN1ÐO2
C5ÐC4ÐN1ÐO2
179.1 (2)
0.6 (4)
C13ÐC12ÐN2ÐO4
C11ÐC12ÐN2ÐO4
� 1.1 (3)
178.28 (19)
Table 2
Hydrogen-bond geometry (A, ).
Ê
ꢀ
DÐHÁ Á ÁA
DÐH
HÁ Á ÁA
DÁ Á ÁA
DÐHÁ Á ÁA
O2ÐH2Á Á ÁN2
O4ÐH4Á Á ÁO1
0.82
0.82
0.93
0.93
2.06
1.84
2.58
2.61
2.862 (2)
2.643 (2)
3.432 (3)
3.453 (3)
164
164
153
152
i
ii
C3ÐH3Á Á ÁO3
Figure 2
A view of packing diagram of (I) along the a axis. Hydrogen bonds are
shown as dashed lines.
C11ÐH11Á Á ÁN1
Symmetry code: (i) 1 � x; y ‡ ; � z; (ii) x �
1
2
1
2
1 1
;
2 2
� y; 1 � z.
ꢁ
Acta Cryst. (2005). C61, o240±o242
Odaba Ës o gÆ lu et al.
C H
8 9
NO
2
o241

organic compounds
Methyl H atoms were located from difference Fourier syntheses
Ê
and re®ned as part of a rigid rotating group, with CÐH = 0.96 A and
Carugo, O., Djinovic, K., Rizzi, M. & Castellani, B. (1991). J. Chem. Soc.
Dalton Trans. pp. 1255±1258.
Castellani, C. B. & Millini, R. (1984). J. Chem. Soc. Dalton Trans. pp. 1461±
1462.
Doslci, N., Stare, J. & Mavri, J. (2001). Chem. Phys. 269, 59±73.
Ï Â
Enchev, V., Ivanova, G., Ugrinov, A. & Neykov, G. D. (1999). J. Mol. Struct.
Uiso(H) = 1.5Ueq(C). Other H atoms were placed geometrically and
re®ned using a riding model, with Csp ÐH = 0.93 A and Uiso(H) =
2
Ê
1.2Ueq(C).
5
08, 149±161.
Data collection: X-AREA (Stoe & Cie, 2002); cell re®nement:
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.
X-AREA; data reduction: X-RED32 (Stoe & Cie, 2002); program(s)
used to solve structure: SHELXS97 (Sheldrick, 1997); program(s)
used to re®ne structure: SHELXL97 (Sheldrick, 1997); molecular
graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to
prepare material for publication: WinGX (Farrugia, 1999).
Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837±838.
Fischer, A., Golding, R. M. & Tennant, W. C. (1965). J. Chem. Soc. pp. 6032±
6035.
Ivanova, G. & Enchev, V. (2001). Chem. Phys. 264, 235±244.
Kasumov, V. T., Kartal, I. & Koksal, F. (2000). Spectrochim. Acta A, 56, 841±
8
50.
Kr zÏ an, A., Crist, D. R. & Hor a k, V. J. (2000). Mol. Struct. (Theochem), 528,
37±244.
2
Kr zÏ an, A. & Mavri, J. (2002). Chem. Phys. 277, 71±76.
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: BM1603). Services for accessing these data are
described at the back of the journal.
Mavri, J. & Grdadolnik, J. (2001a). J. Phys. Chem. A, 105, 2039±2044.
Mavri, J. & Grdadolnik, J. (2001b). J. Phys. Chem. A, 105, 2045±2051.
Rospenk, M., Sobczyk, L., Schah-Mohammedi, P., Limbach, H.-H., Golubev,
N. S. & Melikova, S. M. (2001). Magn. Reson. Chem. 39, S81±S90.
Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of
G oÈ ttingen, Germany.
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ꢁ
o242 Odaba Ës o gÆ lu et al.
8 9
C H NO
2
Acta Cryst. (2005). C61, o240±o242