organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
Compounds (I)±(IV) all lie across centres of inversion and
all have the E,E con®guration at the C N double bonds. In
each of compounds (III) and (IV) (Figs. 1 and 2), the reference
molecule was selected, for the sake of convenience, as that
centred across (12 ; 21 ; 21) in the space groups P1 and P21/c,
respectively.
ISSN 0108-2701
Three-dimensional supramolecular
structures in (E,E)-N,N0-bis(4-nitro-
benzylidene)butane-1,4-diamine and
(E,E)-N,N0-bis(4-nitrobenzylidene)-
hexane-1,6-diamine
In each of compounds (II)±(IV), the nitro groups are
essentially coplanar with the adjacent aryl rings, as shown by
the relevant torsion angles (Table 1) and, likewise, the C1Ð
C11ÐN11ÐC12 fragments are effectively coplanar with these
rings. However, the skeletons in the polymethylene spacer
units adopt conformations which are very far from planar.
In compound (III) (Fig. 1), the molecules are linked into
chains of edge-fused rings, which can alternatively be
described as molecular ladders, by a single CÐHÁ Á ÁO
hydrogen bond (Table 2), and these chains are further linked
into a three-dimensional framework by two independent ꢀ±ꢀ
stacking interactions. The methine C11 atoms at (x, y, z) and
Christopher Glidewell,a* John N. Low,b Janet M. S.
Skakleb and James L. Wardellc
aSchool of Chemistry, University of St Andrews, Fife KY16 9ST, Scotland,
bDepartment of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen
c
Â
Â
AB24 3UE, Scotland, and Instituto de Quõmica, Departamento de Quõmica
Ã
Inorganica, Universidade Federal do Rio de Janeiro, 21945-970 Rio de Janeiro, RJ,
Brazil
Correspondence e-mail: cg@st-andrews.ac.uk
Received 28 October 2005
Accepted 1 November 2005
Online 10 December 2005
In both (E,E)-N,N0-bis(4-nitrobenzylidene)butane-1,4-diam-
ine, C18H18N4O4, (III), and (E,E)-N,N0-bis(4-nitrobenzyl-
idene)hexane-1,6-diamine, C20H22N4O4, (IV), the molecules
lie across centres of inversion in space groups P1 and P21/c,
respectively. In (III), the three-dimensional supramolecular
structure is built from ꢀ-stacked chains of edge-fused R22(30)
rings, while in (IV), chains of edge-fused R22(38) rings are
linked by dipolar nitro±nitro interactions.
Figure 1
The molecule of compound (III), showing the atom-labelling scheme.
Displacement ellipsoids are drawn at the 30% probability level. Atoms
labelled with the suf®x `a' are at the symmetry position (1 x, 1 y,
Comment
In this paper, we describe the structures of two compounds in
the series 4-O2NC6H4CH N±(CH2)n±N CHC6H4NO2, viz.
for n = 4, compound (III), or n = 6, compound (IV) (see
scheme). We have recently reported the molecular and
supramolecular structures of N,N0-bis(4-nitrobenzylidene)-
ethane-1,2-diamine, (II), where n = 2 (Bom®m et al., 2005).
The molecules of (II), which lie across centres of inversion in
the space group P21/n, are linked into sheets by a single CÐ
HÁ Á ÁO hydrogen bond, and these sheets are further linked by
an aromatic ꢀ±ꢀ stacking interaction. By contrast, in (E,E)-1-
(3-nitrophenyl)-4-(4-nitrophenyl)-2,3-diaza-1,3-butadiene, (I),
where there are no methylene groups between the two ±
CH N± units, the centrosymmetric molecules are linked
directly into a three-dimensional framework structure by
means of two independent CÐHÁ Á ÁO hydrogen bonds
(Glidewell et al., 2006). Intrigued by the differences in the
aggregation patterns of these two compounds, we have now
undertaken a more extended study involving compounds (III)
and (IV), and report their structures here.
1
z).
Figure 2
The molecule of compound (IV), showing the atom-labelling scheme.
Displacement ellipsoids are drawn at the 30% probability level. Atoms
labelled with the suf®x `a' are at the symmetry position (1 x, 1 y,
1
z).
Acta Cryst. (2006). C62, o1±o4
DOI: 10.1107/S0108270105035766
# 2006 International Union of Crystallography o1
Glidewell, Christopher
