Three isomeric N-(nitrophenyl)succinimides: Isolated molecules, hydrogen-bonded sheets and a hydrogen-bonded three-dimensional framework

Article abstract of DOI:10.1107/S0108270105004798

Molecules of N-(2-nitrophenyl)succinimide, C₁₀H ₈N₂O₄ are linked into sheets by a combination of C-H...O and C-H...π(arene) hydrogen bonds. Molecules of N-(3-nitrophenyl)succinimide are linked into a three-dimen

Full text of DOI:10.1107/S0108270105004798

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
mean planes of the two rings are 57.4 (2), 46.0 (2) and
ꢀ
39.1 (2) , respectively, while the dihedral angles between the
aryl rings and the nitro groups are 40.0 (2), 4.9 (2) and
ꢀ
ISSN 0108-2701
23.2 (2) , respectively. In isomers (I) and (II), the molecules
have point group C , and in isomer (III), the molecular point
1
group is C ; hence, in each isomer, the molecules are chiral.
2
Three isomeric N-(nitrophenyl)-
succinimides: isolated molecules,
hydrogen-bonded sheets and a
hydrogen-bonded three-dimensional
framework
Thus, for isomer (II) in space group P2 , each crystal contains
1
just one enantiomer provided that inversion twinning is
absent, although the bulk material is racemic. The bond
distances and interbond angles in (I)±(III) show no unusual
values.
a
b
Christopher Glidewell, * John N. Low, Janet M. S.
b
c
Skakle and James L. Wardell
a
School of Chemistry, University of St Andrews, Fife KY16 9ST, Scotland,
b
Department of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen
c
AB24 3UE, Scotland, and Instituto de Qu Âõ mica, Departamento de Qu Âõ mica
Inorg aà nica, Universidade Federal do Rio de Janeiro, 21945-970 Rio de Janeiro,
RJ, Brazil
Correspondence e-mail: cg@st-andrews.ac.uk
Received 9 February 2005
Accepted 10 February 2005
Online 11 March 2005
Molecules of N-(2-nitrophenyl)succinimide, C H N O , are
1
0
8
2
4
linked into sheets by a combination of CÐHÁ Á ÁO and
CÐHÁ Á Áꢀ(arene) hydrogen bonds. Molecules of N-(3-nitro-
phenyl)succinimide are linked into a three-dimensional
framework by a combination of a two-centre CÐHÁ Á ÁO
The molecules of isomer (I) (Fig. 1) are linked into
centrosymmetric dimers by a single CÐHÁ Á ÁO hydrogen
bond, and these dimers are linked into sheets by a single CÐ
HÁ Á Áꢀ(arene) hydrogen bond (Table 1). Aromatic ꢀ±ꢀ
stacking interactions, on the other hand, are absent. Atom C3
in the molecule at (x, y, z) acts as a hydrogen-bond donor to
hydrogen bond and a three-centre CÐHÁ Á Á(O) hydrogen
2
bond. Molecules of N-(4-nitrophenyl)succinimide which lie
across twofold rotation axes in space group C2/c, participate in
no direction-speci®c intermolecular interactions.
nitro atom O21 in the molecule at (1 � x, 1 � y, 1 � z), so
2
generating a centrosymmetric R (16) (Bernstein et al., 1995)
1 1 1
2
Comment
dimer, centred at ( , , ) (Fig. 4). The atoms of type C2 in this
dimer, at (x, y, z) and (1 � x, 1 � y, 1 � z), act as hydrogen-
2
2 2
We report here the structures of three isomeric N-(nitro-
phenyl)succinimides, (I)±(III). These compounds offer, within
the compass of a small molecular skeleton, a wide range of
potential intermolecular interactions, including CÐHÁ Á Á
O(carbonyl/nitro) (each with aromatic and aliphatic CÐH
units as potential donors) and CÐHÁ Á Áꢀ(arene) hydrogen
bonds, aromatic ꢀ±ꢀ stacking interactions, and dipolar
carbonyl±carbonyl and nitro±nitro interactions.
In the 2-nitro and 3-nitro isomers (I) and (II) (Figs. 1 and 2),
the succinimide rings are effectively planar. However, in the
4
rotation axes in space group C2/c, with the reference molecule
-nitro isomer, (III), where the molecules lie across twofold
1
3
selected as one lying across the axis along ( , y, ) (Fig. 3), the
succinimide rings are markedly puckered. The total puckering
2
4
Ê
amplitude Q (Cremer & Pople, 1975) is 0.161 (3) A, and the
2
ꢀ
ring-puckering parameter ' is 90.0 (9) for the atom
2
iii
iii
sequence N1ÐC1ÐC2ÐC2 ÐC1 [symmetry code: (iii)
Figure 1
The molecule of (I), showing the atom-labelling scheme. Displacement
ellipsoids are drawn at the 30% probability level.
3
2
1 � x, y, � z], indicating a half-chair conformation for this
ring. In isomers (I)±(III), the dihedral angles between the
o216 # 2005 International Union of Crystallography
DOI: 10.1107/S0108270105004798
Acta Cryst. (2005). C61, o216±o220

organic compounds
bond donors, respectively, to aryl rings C11±C16 in the mol-
1
ecular structure; there are, in fact, no direction-speci®c inter-
actions between adjacent sheets.
3
3
1
ecules at (1 � x, � + y, � z) and (x, � y, � + z), which
2
2
2
2
1
2
themselves form parts of the dimers centred at ( , 0, 1) and
1
The molecules of (II) are linked into a three-dimensional
framework by a combination of one two-centre CÐHÁ Á ÁO
(
, 1, 0), respectively. In a similar way, aryl rings C11±C16 in
2
the molecules at (x, y, z) and (1 � x, 1 � y, 1 � z) accept
hydrogen bond and one three-centre CÐHÁ Á Á(O) hydrogen
2
1
hydrogen bonds from atoms C2 in the molecules at (1 � x, + y,
bond (Table 2), and the formation of the framework is readily
analysed and described by consideration of each of these
interactions in turn. In the two-centre hydrogen bond,
aromatic atom C16 in the molecule at (x, y, z) acts as a donor
to carbonyl atom O4 in the molecule at (� 1 + x, y, z), so
generating by translation a C(6) (Bernstein et al., 1995) chain
running parallel to the [100] direction (Fig. 6).
2
3
2
1
2
1
2
�
z) and (x, � y, � + z), respectively, which are themselves
1
2
1
2
components of the dimers centred at ( , 1, 1) and ( , 0, 0). In
this manner, a (100) sheet is generated (Fig. 5).
There is a fairly short dipolar contact between carbonyl
iv
1
3
atoms O1 at (x, y, z) and C4 at (1 � x, + y, � z) [O1Á Á ÁC4 =
2
2
iv
iv
Ê
Ê
2
1
(
.959 (2) A, O1Á Á ÁO4 = 3.193 (2) A, C1ÐO1Á Á ÁC4
=
ꢀ
iv
iv
ꢀ
48.7 (2) and O1Á Á ÁC4 ÐO4 = 50.4 (2) ; symmetry code:
In the three-centre hydrogen bond, which is planar, atom
C3 in the molecule at (x, y, z) acts as a donor, via H3A, to nitro
atom O31 in the molecule at (x, y, � 1 + z) and to carbonyl
1
2
3
2
iv) 1 � x, + y, � z], corresponding to an interaction part-
way between the type I and type III motifs (Allen et al., 1998).
However, this interaction occurs within a (100) sheet and
hence does not affect the dimensionality of the supramol-
1
2
atom O1 in the molecule at (� x, + y, � z). The individual
components of this three-centre system thus produce,
respectively, a C(9) chain running parallel to the [001] direc-
tion and generated by translation, and a C(5) chain running
parallel to the [010] direction and generated by the 2 screw
1
1
1
axis along ( , y, ). The action of the two components of this
system, acting together, forms a (100) sheet in the form of a
4,4)-net (Batten & Robson, 1998) built from a single type of
4
4
(
R (23) ring (Fig. 7). The combination of the [100] chain (Fig. 6)
4
3
and the (100) sheet (Fig. 7) suf®ces to generate the three-
dimensional framework.
In the structure of isomer (III) (Fig. 3) there are neither
hydrogen bonds of any type nor aromatic ꢀ±ꢀ stacking
interactions or dipolar interactions; hence, the structure of
(III) consists of isolated molecules.
It is of interest to compare the supramolecular structures of
isomers (I)±(III) with that of the isomeric C-(3-nitrophen-
Figure 2
The molecule of (II), showing the atom-labelling scheme. Displacement
ellipsoids are drawn at the 30% probability level.
Figure 3
The molecule of (III), showing the atom-labelling scheme. Displacement
Figure 4
Part of the crystal structure of (I), showing the formation of an R (16)
2
2
1
1 1
2 2
ellipsoids are drawn at the 30% probability level, and atoms marked with
3
dimer centred at ( , , ). Atoms marked with an asterisk (*) are at the
2
the suf®x A are at the symmetry position (1 � x, y, 2 � z).
symmetry position (1 � x, 1 � y, 1 � z).
ꢁ
Acta Cryst. (2005). C61, o216±o220
Glidewell et al.
Three isomers of C10H N
8 2
O
4
o217

organic compounds
yl)succinimide, (IV) [Cambridge Structural Databse (CSD;
Allen, 2002) refcode TANPUT (Kwiatkowski & Karolak-
Wojciechowska, 1992)]. Compound (IV) crystallizes in the
hydrogen bonds involving one nitro O atom and one carbonyl
O atom as acceptors; however, CÐHÁ Á Áꢀ(arene) hydrogen
bonds and aromatic ꢀ±ꢀ stacking interactions are absent from
the structure of (IV). We also note that, at 293 K, N-(4-
nitrophenyl)maleimide, (V) [CSD refcodes BEDWOX (Fruk
& Graham, 2003) and BEDWOX01 (Moreno-Fuquen et al.,
2003)], is isostructural with (III). The structure of (V), like that
of (III), contains no direction-speci®c intermolecular inter-
actions, despite the different orientations of the CÐH bonds
in the heterocyclic ring of (V).
0
centrosymmetric space group P2 /c, with Z = 2, so that equal
1
numbers of the R and S enantiomers are present in each
crystal. The supramolecular structure is dominated by two NÐ
2
2
HÁ Á ÁO hydrogen bonds, which generate C (8) chains along
[
010]. Although no CÐHÁ Á ÁO hydrogen bonds were
mentioned in the original report, analysis of the reported
atomic coordinates using PLATON (Spek, 2003) shows that
the chains are, in fact, weakly linked into sheets by two such
The intermolecular interactions manifest in the structures
of (I)±(III) are different in all three isomers. In (I), the
structure is determined by one CÐHÁ Á ÁO hydrogen bond and
one CÐHÁ Á Áꢀ(arene) hydrogen bond; both interactions
involve a CH donor rather than an aryl CÐH bond as donor,
2
and the CÐHÁ Á ÁO hydrogen bond has a nitro O-atom
acceptor rather than the usual carbonyl O-atom acceptor;
however, the carbonyl groups do participate in dipolar inter-
actions. In isomer (II), by contrast, where only CÐHÁ Á ÁO
hydrogen bonds occur, both CH and aryl donors participate,
2
and the three-centre hydrogen bond involves both nitro and
carbonyl O atoms as the acceptors. Likewise in (IV), the CÐ
HÁ Á ÁO hydrogen bonds involve both nitro and carbonyl
acceptors. In none of isomers (I)Ð(III) is there any aromatic
ꢀ
±ꢀ stacking interactions, and these interactions are possibly
Figure 5
precluded by the overall molecular conformations. Perhaps
the most surprising feature of the structures of isomers (I)±
(III) is the lack of any direction-speci®c intermolecular
interactions in isomer (III).
A stereoview of part of the crystal structure of (I), showing the formation
of a (100) sheet built from CÐHÁ Á ÁO and CÐHÁ Á Áꢀ(arene) hydrogen
bonds. For clarity, H atoms not involved in the motifs shown have been
omitted
Thus, each of the isomers (I)±(III) exhibits a different range
of intermolecular interactions, and their supramolecular
structures are all of different dimensionality, viz. two- and
three-dimensional in (I) and (II), respectively, contrasted with
isolated molecules in (III). Such differences within a series of
positional isomers are not yet readily predictable, either
heuristically or computationally.
Figure 6
Part of the crystal structure of (II), showing the formation, via a two-
centre CÐHÁ Á ÁO hydrogen bond, of a C(6) chain along [100]. For clarity,
H atoms not involved in the motif shown have been omitted. Atoms
marked with an asterisk (*) or a hash (#) are at the symmetry positions
Figure 7
A stereoview of part of the crystal structure of (II), showing the
formation, via a three-centre CÐHÁ Á Á(O)
2
hydrogen bond, of a (100)
sheet. For clarity, H atoms not involved in the motifs shown have been
omitted.
(� 1 + x, y, z) and (1 + x, y, z), respectively.
ꢁ
o218 Glidewell et al.
8 2
Three isomers of C10H N O
4
Acta Cryst. (2005). C61, o216±o220

organic compounds
Experimental
Data collection
Nonius KappaCCD diffractometer
1067 re¯ections with I > 2ꢅ(I)
For the preparation of compounds (I)±(III), ®nely ground mixtures
containing equimolar quantities of succinic anhydride and the
appropriate nitroaniline were heated in an oil bath at 473 K until
effervescence ceased. The resulting solids were cooled to ambient
temperature and dissolved in chloroform. Activated charcoal was
added and the mixtures were then heated under re¯ux for 10 min; this
process was followed by ®ltration of the hot mixtures. After removal
of the solvent under reduced pressure, crystallization of the solid
products from ethanol gave crystals suitable for single-crystal X-ray
diffraction.
'
scans, and ! scans with ꢇ offsets
Absorption correction: multi-scan
SORTAV; Blessing, 1995, 1997)
min = 0.947, Tmax = 0.964
Rint = 0.042
ꢀ
ꢃ
max = 27.4
(
T
h = � 8 ! 8
k = � 8 ! 9
l = � 12 ! 13
5
1
403 measured re¯ections
152 independent re¯ections
Re®nement
2
2
2
o
2
Re®nement on F
2
w = 1/[ꢅ (F ) + (0.0485P)
2
R[F > 2ꢅ(F )] = 0.031
wR(F ) = 0.078
S = 1.08
+ 0.043P]
where P = (F
(Á/ꢅ)max < 0.001
2
2
2
+ 2F )/3
c
o
Ê
� 3
Ê
� 3
1
1
152 re¯ections
46 parameters
Áꢆmax = 0.22 e A
Compound (I)
Áꢆmin = � 0.21 e A
H-atom parameters constrained
Extinction correction: SHELXL97
Extinction coef®cient: 0.112 (14)
Crystal data
�
3
C
10
H N
8 2
O
4
D
x
= 1.526 Mg m
r
M = 220.18
Monoclinic, P2 =c
Mo Kꢂ radiation
Table 2
Hydrogen-bond geometry (A, ) for (II).
Cell parameters from 2192
re¯ections
Ê
ꢀ
1
Ê
a = 8.3703 (2) A
Ê
b = 8.2500 (1) A
ꢀ
ꢃ = 3.5±27.5
DÐHÁ Á ÁA
DÐH
HÁ Á ÁA
DÁ Á ÁA
DÐHÁ Á ÁA
Ê
c = 14.1375 (3) A
� 1
ꢄ = 0.12 mm
T = 120 (2) K
ꢀ
3
ꢁ
= 101.0185 (10)
Ê
v
C3ÐH3AÁ Á ÁO31
0.99
0.99
0.95
2.48
2.47
2.37
3.193 (2)
3.158 (3)
3.162 (2)
129
127
141
vi
V = 958.27 (3) A
Z = 4
Block, yellow
0.15 Â 0.15 Â 0.10 mm
C3ÐH3AÁ Á ÁO1
vii
C16ÐH16Á Á ÁO4
1
Data collection
Symmetry codes: (v) x; y; z � 1; (vi) � x; y ‡
2
; � z; (vii) x � 1; y; z.
Nonius KappaCCD diffractometer
and ! scans
Absorption correction: multi-scan
SADABS; Sheldrick, 2003)
min = 0.976, Tmax = 0.988
1846 re¯ections with I > 2ꢅ(I)
'
Rint = 0.031
ꢀ
ꢃ
max = 27.5
Compound (III)
(
T
h = � 10 ! 10
k = � 10 ! 10
l = � 18 ! 18
Crystal data
1
2
2 771 measured re¯ections
192 independent re¯ections
C
10
H N O
8 2 4
Mo Kꢂ radiation
M
r
= 220.18
Cell parameters from 1054
re¯ections
Re®nement
Monoclinic, C2=c
a = 10.3731 (19) A
Ê
b = 11.590 (2) A
c = 7.9761 (18) A
ꢁ = 108.135 (16)
Ê
V = 911.3 (3) A
2
2
2
2
ꢀ
Ê
Re®nement on F
2
w = 1/[ꢅ (F ) + (0.0646P)
ꢃ = 3.3±27.6
ꢄ = 0.13 mm
T = 120 (2) K
o
2
� 1
R[F > 2ꢅ(F )] = 0.043
wR(F ) = 0.114
S = 1.10
+ 0.2225P]
where P = (F + 2F )/3
(Á/ꢅ)max < 0.001
2
2
o
2
c
Ê
ꢀ
3
Lath, colourless
0.25 Â 0.11 Â 0.03 mm
Ê
� 3
2
1
192 re¯ections
46 parameters
Áꢆmax = 0.35 e A
Ê
� 3
Áꢆmin = � 0.35 e A
Z = 4
D = 1.605 Mg m
�
3
H-atom parameters constrained
Extinction correction: SHELXL97
Extinction coef®cient: 0.081 (7)
x
Data collection
Nonius KappaCCD diffractometer
and ! scans
Absorption correction: multi-scan
SADABS; Sheldrick, 2003)
min = 0.974, Tmax = 0.996
690 re¯ections with I > 2ꢅ(I)
Table 1
Hydrogen-bond geometry (A, ) for (I).
'
Rint = 0.095
Ê
ꢀ
ꢀ
ꢃ
max = 27.6
(
T
h = � 13 ! 13
k = � 15 ! 15
l = � 10 ! 10
Cg is the centroid of the C11±C16 ring.
9
1
627 measured re¯ections
054 independent re¯ections
DÐHÁ Á ÁA
DÐH
HÁ Á ÁA
DÁ Á ÁA
DÐHÁ Á ÁA
i
C3ÐH3BÁ Á ÁO21
0.99
0.99
2.42
2.75
3.253 (2)
3.638 (2)
141
149
ii
Re®nement
C2ÐH2BÁ Á ÁCg
2
2
2
2
Re®nement on F
2
w = 1/[ꢅ (F ) + (0.0889P)
1
2
3
2
o
Symmetry codes: (i) � x ‡ 1; � y ‡ 1; � z ‡ 1; (ii) � x ‡ 1; y � ; � z ‡ .
2
R[F > 2ꢅ(F )] = 0.058
wR(F ) = 0.167
S = 1.06
+ 0.338P]
where P = (F + 2F )/3
2
2
o
2
c
(Á/ꢅ)max < 0.001
Ê
� 3
Áꢆmax = 0.25 e A
1
7
054 re¯ections
5 parameters
Áꢆmin = � 0.30 e AÊ
� 3
Compound (II)
H-atom parameters constrained
Crystal data
�
3
C
10
H N
8 2
O
4
D
x
= 1.570 Mg m
1
For isomer (I), the space group P2 /c was uniquely assigned from
M
r
= 220.18
Monoclinic, P21
Mo Kꢂ radiation
Cell parameters from 1152
re¯ections
the systematic absences. For isomer (II), the systematic absences
permitted P2 and P2 /m as possible space groups; since the unit-cell
Ê
a = 6.6318 (2) A
1
1
Ê
b = 7.0944 (3) A
ꢀ
ꢃ = 3.2±27.4
1
volume suggested Z = 2, space group P2 was selected and subse-
Ê
c = 10.4260 (5) A
� 1
ꢄ = 0.12 mm
T = 120 (2) K
ꢀ
Ê
quently con®rmed by the successful structure analysis. For isomer
(III), the systematic absences permitted C2/c and Cc as possible space
groups; C2/c was selected and con®rmed by the successful structure
ꢁ
= 108.234 (2)
3
V = 465.90 (3) A
Z = 2
Block, colourless
0.40 Â 0.35 Â 0.30 mm
ꢁ
Acta Cryst. (2005). C61, o216±o220
Glidewell et al.
Three isomers of C10H N
8 2
O
4
o219

organic compounds
analysis. All H atoms were located from difference maps and then
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: SK1817). Services for accessing these data are
described at the back of the journal.
treated as riding atoms, with CÐH distances of 0.95 (aromatic) or
Ê
2
.99 A (CH ) and Uiso(H) values of 1.2Ueq(C). In the absence of any
0
signi®cant anomalous dispersion, the Flack (1983) parameter for
isomer (II) was indeterminate (Flack & Bernardinelli, 2000). Hence,
it was not possible to determine the absolute con®guration of the
molecules in the crystal selected for study (Jones, 1986); however, this
con®guration has no chemical signi®cance. Accordingly, the Friedel
pairs were merged prior to the ®nal re®nements. The data-to-para-
meter ratio for isomer (II) is thus rather low, only 7.89, although the
References
Allen, F. H. (2002). Acta Cryst. B58, 380±388.
Allen, F. H., Baalham, C. A., Lommerse, J. P. M. & Raithby, P. R. (1998). Acta
Cryst. B54, 320±329.
Batten, S. R. & Robson, R. (1998). Angew. Chem. Int. Ed. 37, 1460±1494.
Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem.
Int. Ed. Engl. 34, 1555±1573.
Blessing, R. H. (1995). Acta Cryst. A51, 33±37.
Blessing, R. H. (1997). J. Appl. Cryst. 30, 421±426.
Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354±1358.
Ferguson, G. (1999). PRPKAPPA. University of Guelph, Canada.
Flack, H. D. (1983). Acta Cryst. A39, 876±881.
ꢀ
data set is 99.8% complete to ꢃ = 27.43 .
For compounds (I) and (III), data collection: COLLECT (Hooft,
1999); cell re®nement: DENZO (Otwinowski & Minor, 1997) and
COLLECT; data reduction: DENZO and COLLECT. For
compound (II), data collection: KappaCCD Server Software (Nonius,
Flack, H. D. & Bernardinelli, G. (2000). J. Appl. Cryst. 33, 1143±1148.
Fruk, L. & Graham, D. (2003). Heterocycles, 60, 2307±2313.
Hooft, R. W. W. (1999). COLLECT. Nonius BV, Delft, The Netherlands.
Jones, P. G. (1986). Acta Cryst. A42, 57.
Kwiatkowski, W. & Karolak-Wojciechowska, J. (1992). Acta Cryst. C48, 204±206.
McArdle, P. (2003). OSCAIL for Windows. Version 10. Crystallography
Centre, Chemistry Department, NUI Galway, Ireland.
Moreno-Fuquen, R., Valencia, H., Abonia, R., Kennedy, A. R. & Graham, D.
1
997); cell re®nement: DENZO±SMN (Otwinowski & Minor, 1997);
data reduction: DENZO±SMN. For all compounds, structure solu-
tion: OSCAIL (McArdle, 2003) and SHELXS97 (Sheldrick, 1997);
structure re®nement: OSCAIL and SHELXL97 (Sheldrick, 1997);
molecular graphics: PLATON (Spek, 2003); software used to prepare
material for publication: SHELXL97 and PRPKAPPA (Ferguson,
1
999).
(
2003). Acta Cryst. E59, o1717±o1718.
Nonius (1997). KappaCCD Server Software. Windows 3.11 Version. Nonius
BV, Delft, The Netherlands.
Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276,
Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M.
Sweet, pp. 307±326. New York: Academic Press.
Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of
G oÈ ttingen, Germany.
Sheldrick, G. M. (2003). SADABS. Version 2.10. University of G oÈ ttingen, Germany.
Spek, A. L. (2003). J. Appl. Cryst. 36, 7±13.
X-ray data were collected at the EPSRC X-ray Crystal-
lographic Service, University of Southampton, England; the
authors thank the staff for all their help and advice. JNL
thanks NCR Self-Service, Dundee, for grants which have
provided computing facilities for this work. JLW thanks CNPq
and FAPERJ for ®nancial support.
ꢁ
o220 Glidewell et al.
8 2
Three isomers of C10H N O
4
Acta Cryst. (2005). C61, o216±o220