Crystal structure, conformation and vibrational analysis of a mannich base: 2-[(phenylamino) methyl]-isoindole-1,3-dione

Article abstract of DOI:10.1007/s10870-011-0055-1

The crystal structure of 2-[(phenylamino) methyl]-isoindole-1,3-dione, C₁₅H₁₂N₂O₂, crystallizes in the triclinic space group Pi with cell parameters of a = 7.1176 (2) A, b = 8.5533 (3) A, c = 10.9163 (4) A, α =

Full text of DOI:10.1007/s10870-011-0055-1

J Chem Crystallogr (2011) 41:1120–1123
DOI 10.1007/s10870-011-0055-1
ORIGINAL PAPER
Crystal Structure, Conformation and Vibrational Analysis
of a Mannich Base: 2-[(phenylamino) methyl]-isoindole-1,3-dione
S. Franklin
T. Balasubramanian
•
D. Tamilvendan
•
G. Venkatesa Prabhu
•
Received: 10 November 2010 / Accepted: 7 March 2011 / Published online: 31 March 2011
Ó Springer Science+Business Media, LLC 2011
Abstract The crystal structure of 2-[(phenylamino)
methyl]-isoindole-1,3-dione, C H N O , crystallizes in
Introduction
1
5 12 2 2
the triclinic space group P ı¯ with cell parameters of
Mannich reaction is a three-component condensation reac-
tion involving active hydrogen compound, formaldehyde
and a secondary or tertiary amine [1, 2]. It is an important
C–C bond forming reaction used widely in the synthesis of
secondary and tertiary amine derivatives [3, 4]. It is a key
step in the synthesis of many bioactive molecules [5].
Mannich base compounds have been reported as potential
biological agents. They find applications as anti-tubercular
[6], anti-malarial [7], vasorelaxing [8], anti-cancer [9] and
analgesic drugs [10]. The crystal structure of 2-[(phenyla-
mino) methyl]-isoindole-1,3-dione {PMID}, a Mannich
base compound, reported here is an indole derivative.
Phthalimides [isoindole-1,3-dione] and N-substituted
phthalimides belong to an important class of compounds
because of their interesting biological activities [11–13].
They exhibit cytotoxicity [14] and anti-HIV activity [15].
Anilines are the simplest and one of the most important
aromatic amines used widely in the preparation of poly-
urethane. It is a starting-product for the manufacture of
drugs like paracetamol and several sulfonamide-based
drugs. Present study reports the crystal structure of PMID,
in which a phthalimide and phenylamine molecules are
bridged by a methyl group. This crystal structure has been
determined in order to gain a further insight in its chemical
and pharmaceutical aspects. The aggregation modes and
the hydrogen bonding patterns have been explored.
˚
˚
˚
a = 7.1176 (2) A, b = 8.5533 (3) A, c = 10.9163 (4) A,
a = 95.937 (2)°, b = 102.975 (2)°, c = 108.474 (2)°,
3
V = 603.18 (4) A and Z = 2. This indole derivative is a
˚
Mannich base in which a methyl group bridges the mole-
cules of phthalimide and aniline molecules. The dihedral
angle between the phthalimide and aniline is 75.47 (3)°.
The molecules of the title compound forms a centrosym-
metric hydrogen-bonded dimer through a pair of N–HÁÁÁO
hydrogen bonds. C–HÁÁÁp and an extensive pÁÁÁp interac-
tions, in addition, stabilize the molecular structure. The
compound presented here is V-shaped, the angle at the
methyl bridge [N–C–N] being 115.04 (12)°. Present study
reports the conformation and hydrogen bonding interac-
tions which play an important role in biological functions.
Vibration analysis complement the structure analysed.
Keywords Mannich base Á Phthalimide Á Aniline Á
Crystal structure
S. Franklin Á T. Balasubramanian (&)
Department of Physics, National Institute of Technology,
Tiruchirappalli 620015, Tamilnadu, India
e-mail: bala@nitt.edu
D. Tamilvendan Á G. Venkatesa Prabhu
Department of Chemistry, National Institute of Technology,
Tiruchirappalli, India
Experimental
Preparation
Present Address:
S. Franklin
Equimolar amount of phthalimide and formaldehyde were
dissolved in ethanol and the contents were mixed well at
Department of Physics, Bishop Heber College, Tiruchirappalli
6
20017, Tamilnadu, India
1
23

J Chem Crystallogr (2011) 41:1120–1123
1121
room temperature. To the clear solution obtained equimo-
lar amount of aniline was added and stirred well. After few
days a yellow solid obtained was washed with ethanol
several times and dried in the air oven at 333 K. Good
quality crystals suitable for X-ray analysis were obtained
on crystallizing the product using hot ethanol.
X-ray Diffraction Studies
Single crystal X-ray diffraction data were collected on a
Bruker axs CCD area detector [16] using MoKa radiation
˚
(
k = 0.71073 A) in the range of 2.55° \ h \ 31.0° at
2
73 K. The structure was solved by direct methods using
SHELXS-97 [17] and refined by the full-matrix least-
2
squares methods on F using SHELXL-97 [17]. Hydrogen
Fig. 1 FTIR spectrum of PMID with an inset for the chemical
scheme of PMID
atoms were located from the difference Fourier map and
their positional and isotropic displacement parameters were
refined with a riding model. Summary of the crystal data
and structure refinement for the title compound is provided
in Table 1. Chemical scheme of the present structure is
shown as the inset of Fig. 1. Selected bond lengths and
angles are listed in Table 2.
FTIR Studies
The Fourier Transform Infrared (FTIR) spectrum of the
compound PMID has been recorded in the range of
-
1
400–4000 cm
using KBr pellet with a Perkin Elmer
FTIR spectrophotometer at room temperature. Figure 1
shows the FTIR spectrum of the compound PMID.
Table 1 Crystal data and structure refinement for PMID
Discussion
Formula
15 12 2 2
C H N O
Formula weight
Crystal system
Space group
Cell constants
252.27
Triclinic
Pı¯
Structural Studies
The asymmetric unit of the crystal structure presented here
consists of one molecule of the 2-[(phenylamino) methyl]-
isoindole-1,3-dione {PMID}. An ORTEP-3 [18] diagram
of the crystal structure with the atom labelling scheme is
shown in Fig. 2. The geometrical parameters of the
phthalimide ring system are closer to those values observed
in related compounds [19, 20]. The sum of the angle
˚
a (A)
7.1176(2)
8.5533(3)
˚
b (A)
˚
c (A)
10.9163(4)
95.937(2)
102.975(2)
108.474(2)
603.18(4)
2
a (°)
b (°)
c (°)
2
around N1 is 359.83 (10)° indicating sp hybridization.
˚
However, the N1–C1 [1.3981(15) A] and N1–C8
3
˚
Volume (A )
˚
1.3801(15) A] distances are intermediate between the
[
Z
3
average C –N sp (pyramidal) [1.419(17) A] and C –N
˚
3
ar
ar
D
calc (mg/m )
1.389
2
˚
-
1
)
sp (planar) [1.353(7) A] distances reported by Allen et al.
1987) [21]. The phthalimide unit is essentially planar
l (MoKa) (mm
F (000)
0.09
(
264
making a dihedral angle 75.47(3)° with aniline unit. The
compound PMID is V-shaped with an angle 115.04(12)° at
the methyl bridge [N–C–N].
Crystal size (mm)
0.30 9 0.25 9 0.20
17033
Reflections collected
Data/restraints/parameters
2
Goodness of fit on F
4531/0/172
1.04
The crystal packing of the PMID is stabilized exten-
sively by pÁÁÁp and C–HÁÁÁp interactions which are sum-
marized in Table 3. Part of the crystal structure of PMID,
depicting the hydrogen-bonding interactions and the for-
mation of hydrogen-bonded motif is shown in Fig. 3.
Generally, C–HÁÁÁN intramolecular hydrogen bonds are
Final R indices [I [ 2r(I)]
R indices (all data)
R
R
1
1
= 0.052 wR
= 0.075 wR
2
2
= 0.139
= 0.159
-
3
)
˚
(Dq)min, (Dq)max (e A
-0.30, 0.26
CCDC deposition number
CCDC 728038
123

1
122
J Chem Crystallogr (2011) 41:1120–1123
˚
Table 2 Selected geometric parameters of PMID (A, °)
hydrogen–bonded dimers through a pair of N–HÁÁÁO
hydrogen bonds. The hydrogen–bonded ring motif
C1–O2
1.1986 (15)
1.2070 (15)
1.3981 (15)
1.3801 (15)
1.4707 (18)
1.23 (2)
observed can be represented by the graph-set notation
2
R (12) [25, 26]. The succinimide ring at (x, y, z) is linked
2
C8–O1
N1–C1
by aromatic pÁÁÁp interactions with the benzene rings
N1–C8
(C2–C7) at (1 - x, -y, 1 - z) and (2 - x, -y,1 - z),
lying in different frameworks, with a centroid separation of
N1–C9
N2–C9
˚
3.6559(8) and 3.6590(8) A, respectively. Further, the
N2–C10
1.3963 (18)
111.72 (9)
126.51 (10)
121.60 (10)
122.71 (11)
125.25 (11)
124.50 (11)
115.04 (12)
2.7 (2)
benzene rings (C2–C7) at (x, y, z) and (2 - x, -y, 1 - z),
lying in different frame works are linked by pÁÁÁp stacking
C1–N1–C8
C1–N1–C9
C8–N1–C9
C9–N2–C10
O2–C1–N1
O1–C8–N1
N1–C9–N2
O2–C1–N1–C9
O1–C8–N1–C9
˚
interactions with a centroid separation of 3.6596(8) A.
Further, the benzene rings of the aniline molecule at (x, y,
z) and (2 - x, 1 - y, -z), lying in different frameworks
are linked by pÁÁÁp stacking interactions with a centroid
˚
separation of 3.6919(9) A. These extensive pÁÁÁp interac-
tions (Fig. 3; Table 3) stabilize the crystal packing.
-3.2 (2)
Vibration Studies
C1–N1–C9–N2
C8–N1–C9–N2
N1–C9–N2–C10
C9–N2–C10–C15
C9–N2–C10–C11
-112.06 (14)
73.08 (16)
75.98 (16)
13.7 (2)
The vibrations of various functional groups of the com-
pound PMID were analysed from the FTIR spectrum
recorded (Fig. 1). The spectrum reveals the presence of
aromatic ring and methyl groups. Sharp bands observed at
-168.47 (12)
-
1
3
447 and 3384 cm is assigned to the m(N–H) stretching
-
vibrations. The medium band at 3050 cm is attributed to
1
aromatic m(C–H) stretching vibrations. The absorption in
C6
O1
-
1
the region of 2957 cm is due to the m(C–H) of aliphatic
group. The amide band due to m(C=O) appears at 1765 and
C5
C4
C7
-
1
C8
N1
1
708 cm and amide band due to the d(N–H) in plane and
-
1
m(C–N) vibrations appears at 1510 and 1602 cm . The
N2
C3
C2
C9
C1
C11
C10
O2
C15
C12
C13
C14
Fig. 2 Molecular structure of PMID, showing 20% probability
displacement ellipsoids
˚
Table 3 Hydrogen-bond geometry of PMID (A, °)
D–HÁÁÁA
D–H
HÁÁÁA
DÁÁÁA
D–HÁÁÁA
i
N2–H2ÁÁÁO1
Symmetry code: (i) –x ? 2, -y ? 1, -z ? 1
0.95
2.24
3.1685 (16)
163
2
2
Fig. 3 Part of the crystal structure of PMID, depicting R
hydrogen-bonded ring motif formation. Cg, Cg and Cg
the centroid of C10-C15; C1, C2, C7, C8, N1 and C2–C7 rings,
(12)
observed in majority of the Mannich base compounds
22–24]. However, this kind is absent in the present
structure. The molecule of PMID forms centrosymmetric
1
2
represents
[
respectively. (Dashed lines represent hydrogen bonds)
1
23

J Chem Crystallogr (2011) 41:1120–1123
1123
-
1
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Supplementary Data
Crystallographic data for the structure reported in this work
have been deposited with the Cambridge Crystallographic
Data Center as the supplementary data, CCDC No. 728038.
Copies of the data can be obtained free of charge via
www.ccdc.cam.ac.uk/data_request/cif, or by emailing
data_request@ccdc.cam.ac.uk, or by contacting The
Cambridge Crystallographic Data Centre, 12, Union Road,
Cambridge CB2 1EZ, UK; Fax: ?44 1223 336033.
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