6 Molecular and Crystal Structures of Polymorphic …
253
Table
6.8 Crystallographic
parameters
of
the
four
polymorphs
of
N-(pdimethylaminobenzylidene)-p-nitroaniline
Polymorph I
II
III
IV
Space group P-1
P-1
P2 1 /c
P2 1 2 1 2 1
Z
4
4
4
16
a/Å
9.509 (1)
7.507 (1)
3.989 (1)
64.297 (13)
b/Å
16.200 (1)
16.704 (1)
10.621 (1)
10.789 (1)
c/Å
9.505 (1)
11.051 (1)
31.932 (2)
7.731 (1)
α/°
91.69 (1)
92.79 (1)
90
90
β/°
107.52 (1)
90.30 (1)
95.10 (1)
90
γ/°
101.04 (1)
96.58 (1)
90
90
V /Å 3
1364.5
1374.8
1347.7
5363.1
d/g/cm 3
1.311
1.301
1.327
1.334
Refcode
MABZNA
MABZNA01
MABZNA02
MABZNA03
References Nakai et al. (1976) Nakai et al. (1981) Nakai et al. (1981) Nakai et al. (1981)
(a) I
(b) II
(c) III
(d) IV
Fig. 6.18 Molecular geometries of the four polymorphs of N-(p-dimethylaminobenzylidene)-pnitroaniline viewed from the short (left for I-, II- and IV-forms; upper for III-form) and long molecular directions (right for I-, II- and IV-forms; lower for III-form): a I-form (MABZNA), b II-form
(MABZNA01), c III-form (MABZNA02) and d IV-form (MABZNA03)
the I- and II-forms, which have no significant differences in bond lengths or angles.
The twisted angles of the two phenyl rings to the plane composed of the azomethine
unit and two bonded carbon atoms are similar in both forms, where the aniline and
nitrophenyl rings are twisted out of the plane by approximately 45° and 10°, respectively. The molecular conformation of the III-form is similar to those of the I- and
II-forms. The IV-form unit cell contains four independent molecules, which occur
253
Table
6.8 Crystallographic
parameters
of
the
four
polymorphs
of
N-(pdimethylaminobenzylidene)-p-nitroaniline
Polymorph I
II
III
IV
Space group P-1
P-1
P2 1 /c
P2 1 2 1 2 1
Z
4
4
4
16
a/Å
9.509 (1)
7.507 (1)
3.989 (1)
64.297 (13)
b/Å
16.200 (1)
16.704 (1)
10.621 (1)
10.789 (1)
c/Å
9.505 (1)
11.051 (1)
31.932 (2)
7.731 (1)
α/°
91.69 (1)
92.79 (1)
90
90
β/°
107.52 (1)
90.30 (1)
95.10 (1)
90
γ/°
101.04 (1)
96.58 (1)
90
90
V /Å 3
1364.5
1374.8
1347.7
5363.1
d/g/cm 3
1.311
1.301
1.327
1.334
Refcode
MABZNA
MABZNA01
MABZNA02
MABZNA03
References Nakai et al. (1976) Nakai et al. (1981) Nakai et al. (1981) Nakai et al. (1981)
(a) I
(b) II
(c) III
(d) IV
Fig. 6.18 Molecular geometries of the four polymorphs of N-(p-dimethylaminobenzylidene)-pnitroaniline viewed from the short (left for I-, II- and IV-forms; upper for III-form) and long molecular directions (right for I-, II- and IV-forms; lower for III-form): a I-form (MABZNA), b II-form
(MABZNA01), c III-form (MABZNA02) and d IV-form (MABZNA03)
the I- and II-forms, which have no significant differences in bond lengths or angles.
The twisted angles of the two phenyl rings to the plane composed of the azomethine
unit and two bonded carbon atoms are similar in both forms, where the aniline and
nitrophenyl rings are twisted out of the plane by approximately 45° and 10°, respectively. The molecular conformation of the III-form is similar to those of the I- and
II-forms. The IV-form unit cell contains four independent molecules, which occur