Conformational and configurational disorder in 6-(3,4,5-trimethoxy-phenyl)- 6,7-dihydro-5H-1,3-dioxolo[4,5-g]quinolin-8(5H)-one and 6-(1,3-benzodioxol-5-yl) -6,7-dihydro-5H-1,3-dioxolo[4,5-g]quinolin-8-one: A hydrogen-bonded chain of rings and π-stacked h

Article abstract of DOI:10.1107/S0108270109019556

In 6-(3,4,5-trimethoxy-phen-yl)-6,7-dihydro-5H-1,3-dioxolo[4,5-g]quinolin- 8(5H)-one, C19H19NO6, (I), the six-membered heterocyclic ring adopts a conformation inter-mediate between envelope and half-chair forms; it is disordered over two enantiomeric conf

Full text of DOI:10.1107/S0108270109019556

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
containing the dioxolotetrahydroquinolin-8-one unit have
found application as antimitotic and antitumor agents (Prager
& Thredgold, 1968; Donnelly & Farrell, 1990; Kurasawa et al.,
2000; Zhang et al., 2000). Compounds (I) and (II) have been
prepared here by 6-endo intramolecular cyclization (Low,
ISSN 0108-2701
´
Cobo, Cuervo et al., 2004; Abonıa et al., 2008) from the
corresponding 2-aminochalcones (Low et al., 2002).
Conformational and configurational
disorder in 6-(3,4,5-trimethoxy-
phenyl)-6,7-dihydro-5H-1,3-dioxolo-
[4,5-g]quinolin-8(5H)-one and 6-(1,3-
benzodioxol-5-yl)-6,7-dihydro-5H-
1,3-dioxolo[4,5-g]quinolin-8-one: a
hydrogen-bonded chain of rings and
p-stacked hydrogen-bonded chains
a
a
b
´
Paola Cuervo, ‡ Rodrigo Abonıa, Justo Cobo and
Christopher Glidewellc*
a
´
´
´
Grupo de Investigacion de Compuestos Heterocıclicos, Departamento de Quımica,
b
´
Universidad de Valle, AA 25360 Cali, Colombia, Departamento de Quımica
Inorganica y Organica, Universidad de Jaen, 23071 Jaen, Spain, and cSchool of
Chemistry, University of St Andrews, Fife KY16 9ST, Scotland
Correspondence e-mail: cg@st-andrews.ac.uk
´
´
´
´
Received 22 May 2009
Accepted 22 May 2009
Online 6 June 2009
In 6-(3,4,5-trimethoxyphenyl)-6,7-dihydro-5H-1,3-dioxolo-
[4,5-g]quinolin-8(5H)-one, C19H19NO6, (I), the six-membered
heterocyclic ring adopts a conformation intermediate between
envelope and half-chair forms; it is disordered over two
enantiomeric configurations, with occupancies of 0.879 (3)
and 0.121 (3), leading to positional disorder of the 3,4,5-
trimethoxyphenyl unit. In 6-(1,3-benzodioxol-5-yl)-6,7-di-
hydro-5H-1,3-dioxolo[4,5-g]quinolin-8-one, C17H13NO5, (II),
the molecules are similarly disordered, with occupancies of
0.866 (4) and 0.134 (4). The molecules in (I) are linked by one
three-centre N—Hꢀ ꢀ ꢀ(O)2 hydrogen bond and one two-centre
C—Hꢀ ꢀ ꢀO hydrogen bond to form a complex chain of rings
whose formation is reinforced by two independent aromatic
ꢀ–ꢀ stacking interactions. In (II), a single N—Hꢀ ꢀ ꢀO hydrogen
bond links the molecules into a simple chain, and pairs of
chains are linked by a single aromatic ꢀ–ꢀ stacking inter-
action.
The six-membered heterocyclic ring in (I) is nonplanar; it is,
in fact, disordered over two possible conformations, whose
refined occupancies are 0.879 (3) and 0.121 (3). For the major-
occupancy conformation, the ring-puckering angles (Cremer
& Pople, 1975) are, for the atom sequence N15—C4A—C8A—
C18—C17—C16, ꢁ = 49.2 (3)ꢁ and ’ = 285.1 (4)ꢁ, indicating a
conformation intermediate between the envelope form [for
which the idealized puckering angles are ꢁ = 54.7ꢁ and ’ =
(60k)ꢁ, where k represents an integer] and the half-chair form
[where the corresponding values are 50.8ꢁ and (60k + 30)ꢁ].
However, for the minor-occupancy component, the puckering
angles for the atom sequence N25—C4A—C8A—C18—C27—
C26 are ꢁ = 126.5 (8)ꢁ and ’ = 97.2 (7)ꢁ, indicating a similar
conformation to the major form but with the opposite absolute
configuration. Consistent with this, the configurations at the
stereogenic C atoms C16 and C26 in the major and minor
components are S and R, respectively, in the selected asym-
metric unit. Accordingly, the molecules are all chiral, but
although the centrosymmetric space group readily accom-
modates equal number of the two enantiomers, it appears that
each molecular site can, in principle, be occupied by either
form, leading to the observed configurational and conforma-
tional disorder.
Comment
We report here the structures of the title compounds, (I) and
(II) (Figs. 1 and 2), which we compare with that of the 6-(4-
bromophenyl) analogue, (III) (see scheme), whose structure
was reported several years ago (Low, Cobo, Cuervo et al.,
2004). These structures are of interest because compounds
´
‡ Permanent address: Departamento de Quımica, Universidad Nacional de
´
Colombia, AA 14490 Bogota, Colombia.
o326 # 2009 International Union of Crystallography
doi:10.1107/S0108270109019556
Acta Cryst. (2009). C65, o326–o330

organic compounds
Closely associated with the ring disorder in (I) is the posi-
tional disorder of the entire 3,4,5-trimethoxyphenyl unit,
where the two components occupy similar regions of space
(Fig. 1). For example, the dihedral angle between the planes of
the two rings C111–C116 and C211–C216 is only 3.6 (9)ꢁ, and
having different configurations, S at C16 in the major
component and R at C26 in the minor component. The
enantiomeric nature of the two components is further illu-
strated by the ring puckering angles for the same atom
sequences as in (I) [ꢁ = 54.8 (5)ꢁ and ’ = 298.5 (6)ꢁ for the
major form, and ꢁ = 126 (4)ꢁ and ’ = 114 (4)ꢁ for the minor
form], indicating an almost perfect half-chair form in both
components of (II).
The observed disorder in (I) and (II) has prompted us to re-
examine compound (III) using the original diffraction data,
and this has confirmed that, as originally reported (Low, Cobo,
Cuervo et al., 2004), the molecules in (III) are fully ordered,
with only a single enantiomer occupying each molecular site in
the space group P21/c. The ring-puckering angles in (III)
correspond almost exactly to an envelope conformation for
the nitrogen-containing ring, so that the six-membered ring
conformations in (I)–(III) are all slightly different.
˚
while the C16ꢀ ꢀ ꢀC26 distance is 0.855 (9) A, the O144ꢀ ꢀ ꢀO214
˚
distance, at the far end of this substituent, is only 0.17 (3) A.
For each conformation of the nitrogen-containing ring, the
3,4,5-trimethoxyphenyl substituent occupies an equatorial site,
and it seems probable therefore that the conformational
disorder of the nitrogen-containing ring is a direct conse-
quence of the statistical occurrence of two enantiomeric forms
at each molecular site in an orientation dominated by the bulk
of the 3,4,5-trimethoxyphenyl substituent.
Rather similar disorder was found in (II), but it was found
necessary to treat the entire molecule as disordered over two
sets of sites, again with the major and minor components
The crystallization of (I)–(III) as racemates is wholly to be
expected, as their syntheses utilized no reagents capable of
imparting enantiomeric bias. What is unexpected, however, is
the site occupancy in (I) and (II) by a mixture of enantiomeric
forms. Possibly, the larger the steric bulk of the peripheral
substituents, the more likely the observation of such behaviour
becomes.
Within the fused tricyclic component of (I) there are some
unusual bond distances (Table 1) which provide evidence for
polarization of the electronic structure. In the central carbo-
cyclic ring of this unit, the distances C3A—C4 and C9—C9A
are both significantly shorter than the remaining C—C
distances. In addition, the exocyclic bonds C4A—N15 and
C18—C8A are both short for their types [mean values (Allen
˚
et al., 1987) 1.419 and 1.485 A, respectively; lower-quartile
˚
values 1.412 and 1.478 A], while the ketonic C18—O8 bond is
˚
long for its type (mean value 1.230 A; upper-quartile value
˚
1.215 A). These observations indicate that the polarized form
Figure 1
The molecular structure of (I), showing the two disorder components and
the atom-labelling scheme. Displacement ellipsoids are drawn at the 30%
probability level. The disordered atom sites O18 and O28 are almost
coincident, so that it is not possible to distinguish them in this figure.
(Ia) (see scheme) is a significant contributor to the overall
electronic structure, so that hydrogen bonds (see below and
Table 2) involving either N15 as donor or O18 as acceptor can
be regarded as charge-assisted hydrogen bonds (Gilli et al.,
1994). Entirely similar patterns of distances are found both in
(II) (Table 3) and in (III) (Low, Cobo, Cuervo et al., 2004), and
it is possible that such polarization is typical of compounds
containing this quinolinone ring system. For example, a
comparable pattern is evident in N-acetyl derivative (IV)
´
(Low, Cobo, Ortız et al., 2004).
The methyl C atoms in two of the three methoxy groups in
(I) lie very close to the plane of the adjacent ring, as indicated
by the relevant torsion angles (Table 1), while the plane of the
central methoxy C—O—C fragment containing C118 is almost
orthogonal to the ring plane. The displacements of atoms
C117, C118 and C119 from the mean plane of the adjacent ring
˚
are 0.147 (3), 1.249 (6) and ꢂ0.047 (3) A, respectively. Asso-
ciated with these substituent conformations, the two exocyclic
C—C—O angles at C114 are almost identical, while the pairs
of angles at C113 and C115 differ, as usual, by ca 10ꢁ (Table 1).
The C—O—C angles at O113 and O115 are both significantly
larger than the ideal tetrahedral value.
Figure 2
The molecular structure of (II), showing the two disorder components
and the atom-labelling scheme. Displacement ellipsoids are drawn at the
30% probability level. The atom numbers in the major component all
begin with 1 and those in the minor component all begin with 2.
ꢃ
Acta Cryst. (2009). C65, o326–o330
Cuervo et al. C19H19NO6 and C17H13NO5 o327

organic compounds
One consequence of the very similar location for the 3,4,5-
trimethoxyphenyl substituents in the two disorder compo-
nents in (I) and for the 1,3-benzodioxol-5-yl substituents in
(II) is that, for each compound, the pattern of the inter-
molecular hydrogen bonds is the same for both components
(Tables 2 and 4) and it is therefore sufficient to discuss only the
supramolecular aggregation exhibited by the major compo-
nents. In (I), a three-centre N—Hꢀ ꢀ ꢀ(O)2 hydrogen bond,
involving the O atoms in two of the three methoxy groups as
the acceptors, links pairs of molecules into a cyclic centro-
symmetric dimer (Fig. 3) containing rings of R21(5), R22(14) and
R22(16) types (Bernstein et al., 1995). This dimeric unit is
reinforced by an aromatic ꢀ–ꢀ stacking interaction. The tri-
substituted rings in the two molecules are related by inversion
and hence they are strictly parallel, with an interplanar spacing
Figure 4
˚
˚
of 3.587 (2) A. The ring-centroid separation is 3.749 (2) A,
A stereoview of part of the crystal structure of (I), showing the formation
of a hydrogen-bonded chain of rings running parallel to the [101]
direction. For the sake of clarity, the minor disorder component and H
atoms not involved in the motifs shown have been omitted.
˚
corresponding to a ring-centroid offset of 1.090 (2) A.
A single C—Hꢀ ꢀ ꢀO hydrogen bond utilizing the ketonic O
atom as the acceptor links these cyclic dimers into a chain of
3
rings. Atoms C112 in the molecules at (x, y, z) and (ꢂx + ,
2
3
ꢂy + , ꢂz + 1) are both constituents of the cyclic dimer
2
3
4
1
2
centred at (34, , ). These two atoms act as hydrogen-bond
1
2
donors to atoms O18 in the molecules at (ꢂx + 1, y, ꢂz + )
1
3
1
and (x + , ꢂy + , z + ), respectively, which are themselves
2
2
2
components of the cyclic dimers centred at (14, 43, 0) and (45, 43, 1),
respectively. Hence, centrosymmetric dimers, which are
related by rotation about twofold axes, are linked by paired
C—Hꢀ ꢀ ꢀO hydrogen bonds, forming a second type of R22(14)
ring, and this ring is also reinforced by an aromatic ꢀ–ꢀ
stacking interaction, this time involving pairs of fused carbo-
Figure 5
A stereoview of part of the crystal structure of (I), showing the formation
of a ꢀ-stacked pair of antiparallel hydrogen-bonded chains running
parallel to the [010] direction. For the sake of clarity, the minor disorder
component and H atoms bonded to C atoms have been omitted.
cyclic rings. The carbocyclic rings in the molecules at (x, y, z)
and (ꢂx + 1, y, ꢂz + 12 ) have an interplanar spacing of
˚
˚
3.431 (2) A and a ring-centroid separation of 3.4412 (11) A.
Propagation of the hydrogen bonds and ꢀ–ꢀ stacking inter-
actions by inversion and rotation generates a complex chain of
rings running parallel to the [101] direction (Fig. 4).
The supramolecular aggregation in (II) is much simpler
than that in (I). A single charge-assisted N—Hꢀ ꢀ ꢀO hydrogen
bond involving the two charge-enhanced atoms N15 and O18
links molecules related by translation into a C(6) chain
running parallel to the [010] direction. Pairs of antiparallel
chains, related to one another by inversion, are linked by a
single aromatic ꢀ–ꢀ stacking interaction. The carbocyclic rings
of the fused tricyclic units in the molecules at (x, y, z)
and (ꢂx + 2, ꢂy + 1, ꢂz + 1) are parallel with an interplanar
˚
spacing of 3.341 (5) A; the ring-centroid separation is
˚
3.619 (5) A, corresponding to a ring-centroid offset of
Figure 3
˚
1.391 (5) A (Fig. 5).
Part of the crystal structure of (I), showing the formation of a
centrosymmetric hydrogen-bonded dimer. For the sake of clarity, the
minor disorder component, H atoms bonded to C atoms and the unit-cell
outline have all been omitted. Atoms marked with an asterisk (*) are at
The modes of aggregation apparent for (I) and (II) are
different from each other and from that observed in
4-bromophenyl analogue (III), where N—Hꢀ ꢀ ꢀO and C—
3
the symmetry position (ꢂx + , ꢂy + 32, ꢂz + 1).
2
ꢃ
o328 Cuervo et al. C19H19NO6 and C17H13NO5
Acta Cryst. (2009). C65, o326–o330

organic compounds
Table 2
Hydrogen-bond geometry (A, ) for (I).
Hꢀ ꢀ ꢀO hydrogen bonds individually form C(6) and C(7)
chains, and in combination form sheets of R34(20) rings, while
pairs of these sheets are linked by a C—Hꢀ ꢀ ꢀꢀ(arene)
hydrogen bond to form bilayers (Low, Cobo, Cuervo et al.,
2004). There are no aromatic ꢀ–ꢀ stacking interactions in the
crystal structure of (III), just as there are no significant
C—Hꢀ ꢀ ꢀꢀ(arene) hydrogen bonds in the structures of (I) and
(II).
ꢁ
˚
D—Hꢀ ꢀ ꢀA
D—H
Hꢀ ꢀ ꢀA
Dꢀ ꢀ ꢀA
D—Hꢀ ꢀ ꢀA
N15—H15ꢀ ꢀ ꢀO114i
N15—H15ꢀ ꢀ ꢀO115i
N15—H15ꢀ ꢀ ꢀO214i
N15—H15ꢀ ꢀ ꢀO215i
C112—H112ꢀ ꢀ ꢀO18ii
C212—H212ꢀ ꢀ ꢀO28ii
0.90 (2)
0.90 (2)
0.90 (2)
0.90 (2)
0.95
2.34 (3)
2.38 (2)
2.46 (4)
2.46 (3)
2.51
3.101 (4)
3.186 (3)
3.23 (3)
3.267 (19)
3.40 (3)
3.1 (2)
142.8 (19)
148 (2)
143.7 (19)
150 (2)
155
0.95
2.21
154
3
2
3
2
1
2
Symmetry codes: (i) ꢂx þ ; ꢂy þ ; ꢂz þ 1; (ii) ꢂx þ 1; y; ꢂz þ .
Experimental
For the synthesis of (I), a mixture of 1-(6-amino-1,3-benzodioxol-5-
yl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (Low et al., 2002)
(0.2 g, 0.56 mmol), 2-propanol (6 ml) and 4-toluenesulfonic acid
(50 mg) was heated under reflux for 1.8 h. The mixture was cooled to
ambient temperature and the resulting solid product was collected by
filtration and washed with 2-propanol (yellow luminescent solid, yield
74%, m.p. 471 K). MS m/e (%): 357 (42, [M+]), 190 (100, [M ꢂ
C9H11O3]), 163 (81, [M ꢂ CH2 CHC9H11O3]). For the synthesis of
(II), a mixture of 1-(6-amino-1,3-benzodioxol-5-yl)-3-(1,3-benzo-
dioxol-5-yl)prop-2-en-1-one (0.1 g, 0.32 mmol), 2-propanol (8 ml)
and 4-toluenesulfonic acid (25 mg) was heated under reflux for 5 h.
The mixture was cooled to ambient temperature and the resulting
precipitate was collected by filtration and washed with 2-propanol
(yellow luminescent solid, yield 98%, m.p. 470 K). MS (70 eV) m/e
(%): 311 (100, [M+]), 190 [M ꢂ C7H5O2]. Crystals of both compounds
suitable for single-crystal X-ray diffraction were grown by slow
evaporation of solutions in 2-propanol.
Refinement
R[F2 > 2ꢅ(F2)] = 0.048
wR(F2) = 0.123
S = 1.04
3842 reflections
290 parameters
39 restraints
H atoms treated by a mixture of
independent and constrained
refinement
ꢂ3
˚
Áꢆmax = 0.25 e A
ꢂ3
˚
Áꢆmin = ꢂ0.24 e A
Compound (II)
Crystal data
3
˚
V = 1324.15 (8) A
Z = 4
C17H13NO5
Mr = 311.28
Monoclinic, P21=n
Mo Kꢃ radiation
ꢄ = 0.12 mmꢂ1
T = 120 K
0.17 ꢄ 0.12 ꢄ 0.10 mm
˚
a = 12.9403 (4) A
˚
b = 7.1310 (2) A
˚
c = 14.7736 (7) A
ꢂ = 103.7580 (13)ꢁ
Data collection
Compound (I)
Bruker–Nonius KappaCCD
diffractometer
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003)
Tmin = 0.971, Tmax = 0.988
22707 measured reflections
3079 independent reflections
2143 reflections with I > 2ꢅ(I)
Rint = 0.090
Crystal data
3
˚
C19H19NO6
Mr = 357.35
V = 3344.3 (2) A
Z = 8
Monoclinic, C2=c
Mo Kꢃ radiation
ꢄ = 0.11 mmꢂ1
T = 120 K
0.22 ꢄ 0.18 ꢄ 0.08 mm
˚
a = 27.0927 (8) A
Refinement
˚
b = 9.6631 (4) A
R[F2 > 2ꢅ(F2)] = 0.051
wR(F2) = 0.128
S = 1.04
H atoms treated by a mixture of
independent and constrained
refinement
˚
c = 14.4579 (6) A
ꢂ = 117.925 (2)ꢁ
ꢂ3
˚
Áꢆmax = 0.26 e A
Áꢆmin = ꢂ0.25 e A
3079 reflections
284 parameters
83 restraints
Data collection
ꢂ3
˚
Bruker–Nonius KappaCCD
diffractometer
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003)
Tmin = 0.960, Tmax = 0.992
22407 measured reflections
3842 independent reflections
2951 reflections with I > 2ꢅ(I)
Rint = 0.046
Table 3
Selected bond lengths (A) for (II).
˚
C13A—C14
C14—C14A
C14A—C18A
C18A—C19
C19—C19A
1.358 (3)
1.413 (3)
1.409 (3)
1.419 (3)
1.349 (3)
C19A—C13A
C14A—N15
C18—C18A
C18—O18
1.394 (3)
1.385 (3)
1.450 (3)
1.246 (3)
Table 1
Selected geometric parameters (A, ) for (I).
ꢁ
˚
C3A—C4
C4—C4A
C4A—C8A
C8A—C9
C9—C9A
1.362 (2)
1.410 (2)
1.413 (2)
1.422 (2)
1.352 (2)
C9A—C3A
C4A—N15
C8A—C18
C18—O18
1.393 (2)
1.376 (2)
1.450 (2)
1.230 (3)
Table 4
Hydrogen-bond geometry (A, ) for (II).
O113—C113—C112
O113—C113—C114
C113—O113—C117
O114—C114—C113
O114—C114—C115
124.86 (17)
115.02 (15)
117.34 (15)
119.63 (16)
119.83 (16)
C114—O114—C118
O115—C115—C114
O115—C115—C116
C115—O115—C119
111.99 (17)
114.96 (15)
125.34 (17)
117.35 (15)
ꢁ
˚
D—Hꢀ ꢀ ꢀA
D—H
Hꢀ ꢀ ꢀA
Dꢀ ꢀ ꢀA
D—Hꢀ ꢀ ꢀA
N15—H15ꢀ ꢀ ꢀO18i
0.91 (2)
0.91 (2)
2.29 (2)
2.54 (12)
3.176 (3)
3.12 (2)
164 (3)
122 (12)
N25—H25ꢀ ꢀ ꢀO28i
C112—C113—O113—C117 ꢂ9.3 (4)
C116—C115—O115—C119 ꢂ2.7 (6)
C115—C114—O114—C118 95.1 (5)
Symmetry code: (i) x; y ꢂ 1; z.
ꢃ
Acta Cryst. (2009). C65, o326–o330
Cuervo et al. C19H19NO6 and C17H13NO5 o329

organic compounds
´ ´
JC thanks the Consejerıa de Innovacion, Ciencia y Empresa
It was apparent at an early stage in the refinements that the rings
containing the N atoms exhibited conformational disorder in each
compound, with consequent positional disorder of the substituent at
position 6. This disorder was modelled for (I) using two sets of atomic
sites for atoms Cx6, Cx7 and Ox8 of the fused ring system (where x =
1 for the major component and x = 2 for the minor component) and
for the entire trimethoxyphenyl substituent, with the bonded
distances and the 1,3 nonbonded distances in the minor-occupancy
component restrained to be the same as the corresponding distances
in the major-occupancy component, in each case subject to an s.u.
´
(Junta de Andalucıa, Spain), the Universidad de Jaen (project
reference UJA_07_16_33) and Ministerio de Ciencia e Inno-
´
´
vacion (project reference SAF2008-04685-C02-02) for finan-
cial support. PC and RA thank COLCIENCIAS and
UNIVALLE (Universidad del Valle, Colombia) for financial
support.
˚
value of 0.005 A. In addition, the anisotropic displacement compo-
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: SK3325). Services for accessing these data are
described at the back of the journal.
nents for corresponding partial-occupancy atoms occupying essen-
tially the same regions of space were set to be equal. Subject to these
conditions, the refined occupancies for the two components were
0.879 (3) and 0.121 (3). Adoption of a similar disorder model for (II)
led to some unacceptably short intermolecular Hꢀ ꢀ ꢀH contacts, and
so an alternative model, involving disorder of the entire molecule,
was utilized, subject to the same restraints as employed for (I),
leading to refined occupancy factors of 0.866 (4) and 0.134 (4). All H
atoms were located in difference maps, apart from those in the minor-
occupancy fragments; these were included in calculated positions. All
H atoms bonded to C atoms were then treated as riding atoms in
geometrically idealized positions, with C—H distances of 0.95
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˚
(aromatic), 0.98 (CH3), 0.99 (CH2) or 1.00 A (aliphatic CH), and
Uiso(H) = kUeq(C), where k = 1.5 for the methyl groups, which were
permitted to rotate but not to tilt, and 1.2 otherwise. The N-bound H
atom in (I) was initially treated as a riding atom, with Uiso(H) =
1.2Ueq(N), but in the final cycles of refinement the coordinates of this
Hooft, R. W. W. (1999). COLLECT. Nonius BV, Delft, The Netherlands.
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˚
atom were freely refined, giving an N—H distance of 0.90 (2) A, with
a sum of angles (C4A—N15—C16, C4A—N15—H15 and C16—
N15—H15) of ca 351.7ꢁ. Free refinement of the minor component of
this atom in (II) was not satisfactory and so a distance restraint of
´
Low, J. N., Cobo, J., Nogueras, M., Sanchez, A., Albornoz, A. & Abonia, R.
(2002). Acta Cryst. C58, o42–o45.
˚
0.90 (2) Awas applied to the N—H bonds in both components of (II).
For both compounds, data collection: COLLECT (Hooft, 1999);
cell refinement: DIRAX/LSQ (Duisenberg et al., 2000); data reduc-
tion: EVALCCD (Duisenberg et al., 2003); program(s) used to solve
structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine
structure: SHELXL97 (Sheldrick, 2008); molecular graphics:
PLATON (Spek, 2009); software used to prepare material for
publication: SHELXL97 and PLATON.
´
Low, J. N., Cobo, J., Ortız, A., Cuervo, P., Abonia, R. & Glidewell, C. (2004).
Acta Cryst. E60, o1057–o1059.
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Sheldrick, G. M. (2003). SADABS. University of Gottingen, Germany.
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o330 Cuervo et al. C19H19NO6 and C17H13NO5
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