organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
pyridine rings in (I) and (II) are quite different. In compound
(I), the N1-pyridine ring is nearly coplanar with the benzene
ring, with a dihedral angle of 18.6 (1)ꢁ, which may be due to
stabilization via an intramolecular CÐHÁ Á ÁO hydrogen bond
between C8 and O1 (see Table 2). The N4-pyridine ring forms
a dihedral angle of 59.4 (1)ꢁ with the benzene ring. Such an
arrangement is similar to that found in N,N0-(4,5-dichloro-o-
phenylene)bis(4-tert-butylpyridine-2-carboxamide) (Fun et al.,
1999).
In (I), N2ÐH2B acts as a donor in the three-centre
(bifurcated) N2ÐH2BÁ Á ÁO2 and N2ÐH2BÁ Á ÁN1 interactions,
the former being responsible for the reciprocal orientation of
the two oxamide groups that form a dihedral angle of
64.1 (1)ꢁ, the latter for the orientation of the O1-carboxamide
plane with respect to that of the N1-pyridine, the C4ÐC5Ð
C6ÐO1 torsion angle being 7.8 (4)ꢁ. The N3ÐH3BÁ Á ÁN4
interaction determines the orientation of the O2-carboxamide
plane with respect to that of the N4-pyridine, the N3ÐC13Ð
C14ÐN4 and O2ÐC13ÐC14ÐC15 torsion angles being
9.5 (3) and 11.6 (4)ꢁ, respectively. The orientation of the
two carboxamide-2-pyridine substituents with respect to the
benzene plane is de®ned by the C6ÐN2ÐC7ÐC8 and C13Ð
N3ÐC12ÐC11 torsion angles of 23.7 (4) and 130.3 (3)ꢁ,
respectively. The weak C11ÐH11AÁ Á ÁO2i interaction (Table 2)
contributes to the crystal packing [symmetry code: (i) x, y 1,
z].
ISSN 0108-2701
N,N0-(1,2-phenylene)bis(pyridine-2-
carboxamide) and N,N0-(1,2-cyclo-
hexanediyl)bis(pyridine-2-carbox-
amide) toluene hemisolvate
Jun Lin, Jun-Yong Zhang, Yan Xu, Xiao-Kang Ke and
Zijian Guo*
Coordination Chemistry Institute, State Key Laboratory of Coordination Chemistry,
Nanjing University, Nanjing 210093, People's Republic of China
Correspondence e-mail: zguo@netra.nju.edu.cn
Received 25 September 2000
Accepted 8 November 2000
The crystal structures of N,N0-(1,2-phenylene)bis(pyridine-2-
carboxamide), C18H14N4O2, (I), and N,N0-(1,2-cyclohexane-
diyl)bis(pyridine-2-carboxamide) have been determined, the
latter
compound
as
the
toluene
hemisolvate,
C18H20N4O2Á0.5C7H8, (II). In (I), the benzene ring is nearly
coplanar with one of the pyridine rings and forms a dihedral
angle of 59.4 (1)ꢁ with the other. However, in (II), the
dihedral angle of the two pyridine rings is 70.0 (1)ꢁ.
In compound (II), the two pyridine rings form a dihedral
angle of 70.0 (1)ꢁ and the cyclohexane ring adopts a chair
conformation, with a total puckering amplitude (Cremer &
Ê
Pople, 1975) QT = 0.559 (2) A. The two pyridine-2-carbox-
amide substituents are approximately perpendicular to the
cyclohexane ring, the dihedral angles they form with the least-
squares plane through cyclohexane being 84.8 (1) and
Comment
Functional mimics of manganese superoxide dismutase (Mn-
SOD) are of great potential as therapeutic agents (Riley,
1999), for example, manganese porphyrin derivatives, which
show powerful anti-in¯ammatory effects due to their multiple
scavenging activities (Cuzzocrea et al., 1999), and N-con-
taining macrocyclic manganese complexes, which have high
catalytic SOD activity and are chemically and biologically
stable in vivo (Salvemini et al., 1999). In the latter case, the
introduction of a fused cyclohexane group enhances the
kinetic and thermodynamic stabilities of the manganese
complexes. Therefore, we designed and synthesized the title
compounds, (I) and (II), which each contain two pyridine and
two amide moieties. The MnII and MnIII complexes of the title
compounds were also synthesized, and preliminary data
showed that the MnIII complexes possess potent SOD activity
in human blood plasma and platelet.
Figure 1
The structure of (I) showing 50% probability displacement ellipsoids and
the atom-numbering scheme. H atoms are drawn as small spheres of
arbitrary radii.
The molecular structures of (I) and (II) are shown in Figs. 1
and 2, respectively. It is notable that the orientations of the
ꢀ
192 # 2001 International Union of Crystallography
Printed in Great Britain ± all rights reserved
Acta Cryst. (2001). C57, 192±194