organic compounds
et al., 1997), in contrast to what is observed here in the crys-
talline phase.
Table 1
Hydrogen-bond geometry (A, ).
˚
ꢁ
The two molecules in the unit cell have a dihedral angle of
ꢁ
D—Hꢀ ꢀ ꢀA
D—H
Hꢀ ꢀ ꢀA
Dꢀ ꢀ ꢀA
D—Hꢀ ꢀ ꢀA
1
9.07 (6) between their mean planes. Each molecule of a
N11—H11ꢀ ꢀ ꢀO21
0.88
0.88
1.97
1.94
2.844 (2)
2.821 (2)
176
178
particular conformation (cis or trans) is related to its nearest
neighbour of the same conformation through a glide plane.
Each molecule is connected to another molecule of a
i
N21—H21ꢀ ꢀ ꢀO11
Symmetry code: (i) ꢂx þ 1; ꢂy þ 2; ꢂz þ 1.
different conformation through N—Hꢀ ꢀ ꢀO hydrogen bonding,
4
resulting in a tetrameric arrangement [graph-set R (16)], with
each tetramer containing two molecules of each conformation.
Due to the nearly planar backbone of the molecule, the
4
H atoms were positioned geometrically and allowed to ride on
their respective parent atoms, with bond lengths of 0.95 (C—H) and
˚
0.88 A (N—H), and isotropic displacement parameters 1.2 times Ueq
of the parent atom.
hydrogen bonds are almost linear, with N—Hꢀ ꢀ ꢀO angles of
ꢁ
1
78 and 176 for the two isomers, respectively. The intra-
Data collection: SMART-NT (Bruker, 1998); cell refinement:
SAINT-Plus (Bruker, 1999); data reduction: SAINT-Plus; program(s)
used to solve structure: SHELXS97 (Sheldrick, 2008); program(s)
used to refine structure: SHELXL97 (Sheldrick, 2008); molecular
graphics: PLATON (Spek, 2003) and ORTEP-3 (Farrugia, 1997);
software used to prepare material for publication: WinGX (Farrugia,
molecular Nꢀ ꢀ ꢀO distances are slightly shorter than those in
acetanilide and related acetamides, such as paracetamol
˚
(2.894–2.967 A; Wasserman et al., 1985; Johnson et al., 1995),
all of which adopt only the trans conformation in the solid
state.
1999).
Experimental
The authors thank the IUCr for a PhD grant (to BO), NRF
for financial support (No. GUN2069064) and the University of
Witwatersrand for providing the experimental facilities.
N-Phenylformamide was synthesized according to the procedure of
Ugi et al. (1965). Commercially available aniline (Aldrich, purity >
9
5%) was heated in a tenfold excess of formic acid for a period of
5 h at 363 K. The excess formic acid was removed under vacuum to
1
give a brown liquid which was treated with dilute hydrochloric acid
0.1 M HCl) and ethyl acetate. The organic layer was separated from
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: GD3183). Services for accessing these data are
described at the back of the journal.
(
the aqueous layer, dried over magnesium sulfate and distilled under
vacuum. An off-white solid was obtained in good yield. The first
suitable single crystals of N-phenylformamide were obtained by
crystallization from ethyl acetate on work-up of the reaction mixture.
Only subsequent to their growth, which took almost a year, was it
possible to grow the same crystals (as established by X-ray powder
diffraction) from various solvents by slow evaporation (chloroform,
ethanol, dichloromethane, ethyl acetate, dimethyl sulfoxide and
tetrahydrofuran). The powder was recrystallized from a variety of
solvents, giving crystals suitable for single-crystal X-ray diffraction
References
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1
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=
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Crystal data
NO
= 121.14
˚
V = 2504.1 (4) A
3
C
M
7
H
7
r
Z = 16
Mo Kꢃ radiation
Monoclinic, C2=c
˚
ꢂ1
a = 31.177 (3) A
ꢄ = 0.09 mm
T = 173 (2) K
˚
b = 6.1229 (5) A
˚
c = 14.3335 (12) A
0.53 ꢃ 0.20 ꢃ 0.14 mm
ꢁ
ꢂ = 113.771 (2)
Data collection
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Bruker SMART CCD area-detector
diffractometer
2732 independent reflections
1953 reflections with I > 2ꢅ(I)
Rint = 0.026
7327 measured reflections
2135–2141.
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Refinement
2
2
R[F > 2ꢅ(F )] = 0.040
wR(F ) = 0.110
163 parameters
H-atom parameters constrained
2
˚
ꢂ3
Áꢆmax = 0.19 e A
S = 1.03
2732 reflections
Áꢆmin = ꢂ0.18 e A˚
ꢂ3
785.
ꢄ
o138 Omondi et al.
7 7
C H NO
Acta Cryst. (2008). C64, o137–o138