Cyclopentadecanone 2,4-dinitrophenylhydrazone

Article abstract of DOI:10.1107/S0108270108002898

In the title compound, C21H32N4O4, no disorder is present in the 15-membered hydro-carbon ring, which exists in an unsymmetrical quinquangular [12345] conformation. The 2,4-dinitro-phenyl-hydrazone group is approximately perpendicular to the C15 ring, with a dihedral angle of 84.66 (1)° between their best planes.

Full text of DOI:10.1107/S0108270108002898

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
ISSN 0108-2701
Cyclopentadecanone 2,4-dinitro-
phenylhydrazone
Eric A. Noe,a Diwakar M. Pawara and Frank R. Fronczekb*
aDepartment of Chemistry, Jackson State University, 1400 J. R. Lynch Street, Jackson,
MS 39217-0510, USA, and bDepartment of Chemistry, Louisiana State University,
Baton Rouge, LA 70803-1804, USA
Correspondence e-mail: ffroncz@lsu.edu
Received 11 December 2007
Accepted 25 January 2008
Online 9 February 2008
Figure 1
Displacement ellipsoid plot (50% probability) of cyclopentadecanone
2,4-dinitrophenylhydrazone, (I).
In the title compound, C21H32N4O4, no disorder is present in
the 15-membered hydrocarbon ring, which exists in an
unsymmetrical quinquangular [12345] conformation. The
2,4-dinitrophenylhydrazone group is approximately perpendi-
cular to the C15 ring, with a dihedral angle of 84.66 (1)ꢀ
between their best planes.
macrocyclic rings, a large number of minimum-energy struc-
tures can be populated, due to the existence of a high degree
of rotational freedom. For example, 262 low-energy confor-
mations were found within 3 kcal molÀ1 by MM2 for cyclo-
heptadecane (Saunders et al., 1990).
The crystal structure of cyclopentadecanone phenylsemi-
carbazone showed an ordered structure with hydrogen-
bonded dimers (van den Hoek et al., 1979), and an unexpected
quadrangular conformation, viz. [3435], was found for the C15
ring. An incomplete X-ray study of cyclopentadecanone was
reported (Groth, 1976), but no comment on conformation was
made. We have recently reported (Noe et al., 2008) the details
of the structure of cyclopentadecanone, in which the C15 ring
has the quinquangular [13353] conformation. A preliminary
X-ray study of cyclopentadecanone oxime indicated that the
structure is highly disordered (Groth, 1979).
Comment
Semiquantitative calculations for cyclopentadecane, (II),
indicated that the first five lowest-energy conformations
considered were all quinquangular and that the [33333]
conformation was the most stable (Dale, 1973). Five triangular
conformations were found among the next nine conformations
in order of energy, but quadrangular conformations were
absent (Dale, 1973).
Although cyclopentadecanone 2,4-dinitrophenylhydrazone,
(I), was reported by Brady (1931), no structural data are
available in the literature. This paper reports an X-ray analysis
of the crystal structure of (I) at 90 K. Representative torsion
angles defining the conformation of the 15-membered ring are
listed in Table 1. The 15-membered ring is present in a quin-
quangular [12345] conformation with C1 symmetry, based on
the method of Dale (1973). In that system of conformational
designation, corner positions are defined, and the numbers of
bonds between adjacent corners are listed in brackets, in order
of increasing numbers. Corners that are not on adjacent C
atoms are readily recognized by having gauche dihedral angles
of the same sign on either side. For (I), these are found at ring
carbons 2, 6, and 9 in Fig. 1. Adjacent corners can be more
difficult to recognize. Using the examples given for cyclo-
undecane, cyclotridecane, and cyclopentadecane by Anet &
Rawdah (1978), we also assign carbons 11 and 12 as corners.
The dihedral angle centered on these two C atoms is
À78.94 (18)ꢀ, and the dihedral angles on either side of it are
155.55 (15) and 178.42 (14)ꢀ, which would correspond to a
MOLBUILD (Boyd, 1968; Boyd et al., 1973) force-field
calculations for cyclopentadecane also found five low-energy
quinquangular conformations, with the [33333] conformation
of lowest strain energy (Anet & Rawdah, 1978). The low-
1
temperature H and 13C NMR spectra of (II) showed line
broadening at the lowest attainable temperatures of 123 and
127 K, respectively, but decoalescence was not observed in
either case (Cheng, 1973). Pawar et al. (2008) later recorded
the 13C NMR spectra at temperatures to 100.9 K; spectra at
the lowest temperatures were substantially more complicated
than the two peaks in a ratio of 2:1 expected for the [33333]
conformation at slow exchange. This conformation could be
present but cannot be the sole conformation populated. In
Acta Cryst. (2008). C64, o139–o141
doi:10.1107/S0108270108002898
# 2008 International Union of Crystallography o139

organic compounds
Table 1
Selected geometric parameters (A, ).
ꢀ
˚
N1—C1
N1—N2
1.288 (2)
1.3891 (19)
N2—C16
1.356 (2)
C1—N1—N2
116.64 (14)
C16—N2—N1
118.84 (13)
C15—C1—C2—C3
C1—C2—C3—C4
C2—C3—C4—C5
C3—C4—C5—C6
C4—C5—C6—C7
C5—C6—C7—C8
C6—C7—C8—C9
C7—C8—C9—C10
C8—C9—C10—C11
66.69 (18)
73.82 (18)
C9—C10—C11—C12
C10—C11—C12—C13
C11—C12—C13—C14
C12—C13—C14—C15
C13—C14—C15—C1
C14—C15—C1—C2
N1—C1—C15—C14
C1—N1—N2—C16
155.55 (15)
À78.94 (18)
178.42 (14)
176.39 (14)
61.5 (2)
À178.22 (14)
178.25 (15)
À72.9 (2)
À71.38 (19)
173.55 (14)
À72.99 (18)
À74.00 (19)
À122.89 (16)
63.3 (2)
À174.11 (15)
Table 2
Hydrogen-bond geometry (A, ).
Figure 2
The unit cell of (I), showing intramolecular hydrogen bonding and nitro–
nitro contacts as dashed lines.
ꢀ
˚
D—HÁ Á ÁA
D—H
HÁ Á ÁA
1.979 (18)
DÁ Á ÁA
D—HÁ Á ÁA
N2—H2NÁ Á ÁO1
0.869 (18)
2.6254 (18)
130.2 (15)
gauche bond, surrounded by two that are close to anti. These
dihedral angles are similar to the values around the one-bond
segment of the [13353] conformation of cyclopentadecane, as
calculated by Anet & Rawdah (1978) (166, À78, and 150ꢀ).
The section of the ring between C12 and C2 is a five-bond
segment between corners. Thus, beginning at corner C12 and
proceeding clockwise in Fig. 1, the designation in (I) is [12345].
The C1—N1—N2—C16 torsion angle is À174.11 (15)ꢀ. The
2,4-dinitrophenylhydrazone group is nearly planar, with a
Crystal data
C21H32N4O4
Mr = 404.51
Triclinic, P1
a = 7.2486 (14) A
˚
b = 8.3234 (15) A
ꢂ = 97.017 (13)ꢀ
3
V = 1027.3 (3) A
Z = 2
Mo Kꢀ radiation
ꢃ = 0.09 mmÀ1
T = 90 K
0.33 Â 0.10 Â 0.02 mm
˚
˚
˚
c = 17.731 (3) A
ꢀ = 103.419 (12)ꢀ
ꢁ = 94.044 (9)ꢀ
˚
mean deviation of 0.053 A for its 14 non-H atoms, and a
˚
maximum deviation of 0.208 (1) A for atom O4. It is nearly
Data collection
perpendicular to the hydrocarbon ring, forming a dihedral
angle of 84.66 (1)ꢀ with the best plane of the C15 ring. Those
˚
15 C atoms exhibit a mean deviation of 0.382 A from copla-
Nonius KappaCCD diffractometer
with an Oxford Cryosystems
Cryostream cooler
4936 independent reflections
3372 reflections with I > 2ꢄ(I)
Rint = 0.038
˚
narity, with a maximum deviation of 0.835 (1) A for atom C1.
16738 measured reflections
A projection showing intramolecular hydrogen bonding as
dashed lines is shown in Fig. 2, which also illustrates close
intermolecular OÁ Á ÁO contacts between nitro groups [O1Á Á Á
Refinement
R[F2 > 2ꢄ(F2)] = 0.051
wR(F2) = 0.104
S = 1.01
4936 reflections
266 parameters
H atoms treated by a mixture of
independent and constrained
refinement
˚
O1(2 À x, Ày, 1 À z) = 2.865 (2) A and O2Á Á ÁO4(x + 1, y, z) =
˚
3.004 (2) A].
À3
˚
Áꢅmax = 0.37 e A
À3
˚
N—HÁ Á ÁO hydrogen bonding (Table 2) results in a discrete
six-membered ring [graph set S(6); Etter, 1990]. Also evident
in Fig. 2 is stacking of the parallel benzene rings related by the
Áꢅmin = À0.24 e A
H atoms on C atoms were placed in calculated positions, guided by
˚
difference maps, with C—H bond distances in the range 0.95–0.99 A
1
1 1
˚
inversion center at (2, 2, 2). The interplanar spacing is 3.295 A,
but the rings are slipped, such that the centroid–centroid
and with Uiso(H) values of 1.2Ueq(C), and thereafter treated as riding.
The N—H hydrogen was refined freely.
˚
distance is 3.557 A.
Data collection: COLLECT (Nonius, 2000); cell refinement:
DENZO and SCALEPACK (Otwinowski & Minor, 1997); data
reduction: DENZO and SCALEPACK; program(s) used to solve
structure: SIR97 (Altomare et al., 1999); program(s) used to refine
structure: SHELXL97 (Sheldrick, 2008); molecular graphics:
ORTEP-3 for Windows (Farrugia, 1997); software used to prepare
material for publication: SHELXL97.
Experimental
Cyclopentadecanone 2,4-dinitrophenylhydrazone, (I), was synthe-
sized by treatment of cyclopentadecanone (0.8 g) with a 2,4-dinitro-
phenylhydrazine solution (12 ml) prepared from 2,4-dinitrophenyl-
hydrazine (1 g), concentrated sulfuric acid (5 ml), water (8 ml), and
ethanol (25 ml). The dinitrophenylhydrazone derivative immediately
precipitated from the solution, and was isolated by filteration, washed
with water, and recrystallized from ethanol [m.p. 373–375 K; litera-
ture m.p. 378 K (Brady, 1931)]. The purity of the sample was estab-
lished by its 13C NMR spectrum.
The synthesis was carried out at Jackson State University,
and support from NSF–CREST (HRD-9805465) is acknowl-
edged. X-ray data were collected at Louisiana State Univer-
ꢁ
o140 Noe et al. C21H32N4O4
Acta Cryst. (2008). C64, o139–o141

organic compounds
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USA.
Dale, J. (1973). Acta Chem. Scand. 27, 1115–1129.
Etter, M. C. (1990). Acc. Chem. Res. 23, 120–126.
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.
sity. The purchase of the diffractometer was made possible by
grant No. LEQSF(1999–2000)-ENH-TR-13, administered by
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Supplementary data for this paper are available from the IUCr electronic
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described at the back of the journal.
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Noe et al. C21H32N4O4 o141