N,N′-Bis(2-hydroxy-benzyl-idene)pentane-1,5-diamine

Article abstract of DOI:10.1107/S0108270107037900

In the title potential O,N,N′,O′-tetra-dentate Schiff base ligand {systematic name: 2,2′-[pentane-1,5-diylbis(nitrilo-methyl-idyne)] diphenol}, C19H22N2O2, the mutual orientation of the three planar fragments determines the conformation of the mol-ecule.

Full text of DOI:10.1107/S0108270107037900

organic compounds
Ê
Acta Crystallographica Section C
Crystal Structure
fragment A and 0.067 (3) A for fragment B, and the central
pentane chain (C), which adopts the exended conformation
Ê
Communications
and is planar to within 0.044 (2) A. The corresponding dihe-
ISSN 0108-2701
dral angles are: A/C = 78.4 (2)ꢀ, B/C = 62.0 (3)ꢀ and A/B =
55.4 (1)ꢀ. It should be noted that the conformation is not
symmetrical. For fragment A, atom N8 is almost coplanar with
the plane of the pentane chain [N8ÐC9ÐC10ÐC11 torsion
N,N0-Bis(2-hydroxybenzylidene)-
pentane-1,5-diamine
ꢀ
Ê
angle 177.1 (3) ], while atom N14 is displaced by almost 1.5 A
[N14ÐC13ÐC12ÐC11 = 68.0 (4)ꢀ] from this plane.
In the analogues of (I) with different aliphatic chain lengths,
two conformations are observed, depending on the presence
of an even or odd number of atoms in the chain. This is related
to the symmetry of the molecule, which is also a function of
Izabela Pospieszna-Markiewicz, Michaø Kozøowski,
Wanda Radecka-Paryzek and Maciej Kubicki*
Department of Chemistry, Adam Mickiewicz University, Grunwaldzka 6,
Â
60-780 Poznan, Poland
Correspondence e-mail: mkubicki@amu.edu.pl
Received 20 July 2007
Accepted 1 August 2007
Online 24 August 2007
In the title potential O,N,N0,O0-tetradentate Schiff base ligand
{systematic name: 2,20-[pentane-1,5-diylbis(nitrilomethyl-
idyne)]diphenol}, C19H22N2O2, the mutual orientation of the
three planar fragments determines the conformation of the
molecule. The dihedral angles between the planes of the two
salicylidene groups and the plane of the central extended
pentane chain are 78.4 (2) and 62.0 (3)ꢀ, and the angle
between the terminal ring planes is 55.4 (1)ꢀ. Strong intra-
molecular OÐHÁ Á ÁN hydrogen bonds close almost-planar six-
membered rings, and the OÐH bonds are elongated as a result
of hydrogen-bond formation.
Figure 1
The molecule of (I), showing the atom-numbering scheme. Displacement
ellipsoids are drawn at the 50% probability level and H atoms are shown
as small spheres of arbitrary radii. The three fragments are denoted A, B
and C.
Comment
Much effort has been devoted in recent years to the design
and synthesis of salicylaldimines and their metal complexes
displaying binding properties toward deoxyribonucleic acid
(DNA), with the aim of developing novel therapeutic agents
which prevent the growth and replication of cancerous cells
(Silvestri et al., 2007). Among the chemical moieties which
have been used as part of chemotherapeutic agents are
biogenic polyamines (Karigiannis & Papaioannou, 2000). The
incorporation of biogenic polyamine fragments with ¯exibility
and strong af®nity for nucleic acids can prompt the emergence
of new architectures with novel physicochemical properties
and potential applications in technology and pharmaceutics. It
seemed, therefore, to be of interest for us to synthesize the
new salicylaldimine system derived from cadaverine, a
biogenic amine.
The conformation of the title compound, (I), and its
analogues can be described by the mutual orientation of three
approximately planar fragments, A, B and C (Fig. 1): two
salicylidene groups, for which the maximum deviations from
Figure 2
The crystal packing of (I), as seen approximately along the c direction.
Ê
the least-squares plane through nine atoms are 0.018 (3) A for
Acta Cryst. (2007). C63, o559±o561
DOI: 10.1107/S0108270107037900
# 2007 International Union of Crystallography o559

organic compounds
Crystal data
the number of atoms in the aliphatic chain. For aliphatic
chains with an even number of C atoms, the molecule can be
centrosymmetric, with the centre of symmetry situated at the
middle of the central CÐC bond. In this case, due to the
symmetry, the terminal ring planes have to be exactly parallel.
This symmetry is realised in the analogues of (I) with n = 2
(Bresciani Pahor et al., 1978; in this case the symmetry is only
approximate), n = 4 (Kennedy & Reglinski, 2001), n = 6
(Sheikhshoaie & Sharif, 2006) and n = 10 (Yu, 2006). The same
symmetry is also observed for a dioxo derivative of the n = 8
compound, viz. 2,2-[3,6-dioxa-1,8-octanediylbis(nitrilomethyl-
idene)]bisphenol (Etemadi et al., 2004).
3
Ê
V = 825.88 (14) A
C19H22N2O2
Mr = 310.39
Monoclinic, Pc
Z = 2
Mo Kꢁ radiation
1
Ê
a = 16.3631 (18) A
Ê
ꢂ = 0.08 mm
T = 100 (1) K
b = 5.6428 (5) A
Ê
c = 9.1251 (8) A
ꢀ = 101.418 (10)ꢀ
0.45 Â 0.3 Â 0.2 mm
Data collection
Kuma KM-4 CCD four-circle
diffractometer
8735 measured re¯ections
1868 independent re¯ections
1484 re¯ections with I > 2ꢃ(I)
Rint = 0.033
When the number of C atoms in the chain is odd, the
molecule cannot be centrosymmetric, and this is the case for
(I), as well as for the molecules with n = 1, which lies on a
twofold axis (Novitchi et al., 2002), and n = 3 (Elderman et al.,
1991), with the molecule on a general position.
Interestingly, despite the different conformations, in three
`intermediate-length' cases (n = 4, 5 and 6), the shape of the
unit cell is similar. In particular, the b axes, which are parallel
to the twofold screw axes for n = 4 and n = 6, are almost equal
Re®nement
R[F2 > 2ꢃ(F2)] = 0.063
wR(F2) = 0.113
S = 1.15
1868 re¯ections
216 parameters
2 restraints
H atoms treated by a mixture of
independent and constrained
re®nement
3
Ê
Áꢄmax = 0.36 e A
3
Ê
0.25 e A
Áꢄmin
=
Table 1
Hydrogen-bond geometry (A, ).
ꢀ
Ê
Ê
(ca 5.7 A). In the case of (I), a pseudo-21 axis can be found
along b (Fig. 2).
DÐHÁ Á ÁA
DÐH
HÁ Á ÁA
DÁ Á ÁA
DÐHÁ Á ÁA
Short intramolecular OÐHÁ Á ÁN hydrogen bonds serve to
O1ÐH1Á Á ÁN8
C13ÐH13AÁ Á ÁO17i
Symmetry code: (i) x; y ‡ 1; z ‡ 12.
1.00 (7)
1.20 (6)
0.99
1.64 (7)
1.55 (6)
2.60
2.552 (5)
2.555 (5)
3.533 (6)
148 (6)
136 (5)
156
O17ÐH17Á Á ÁN14
close the almost planar six-membered rings [maximum
Ê
deviations of 0.03 (3) and 0.06 (3) A for fragments A and B,
respectively]. The H atoms involved in these bonds (H1 and
H17) are signi®cantly displaced towards acceptor N atoms; the
re®ned OÐH distances are long in comparison with typical
values. The reliability of these results is demonstrated by the
difference Fourier maps (Fig. 3) calculated for a model
without these H atoms.
The H atoms of the hydroxy groups were found in a difference
Fourier map (cf. Fig. 3) and their positional and isotropic displace-
ment parameters were re®ned (see Table 1). The other H atoms were
placed in idealized positions and re®ned as riding, with CÐH = 0.95±
Ê
0.99 A and Uiso(H) = 1.2Ueq(C). Since the molecule is not chiral and
lacks any heavy atoms, Friedel pairs were merged before the ®nal
re®nement.
Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell
re®nement: CrysAlis RED (Oxford Diffraction, 2006); data reduc-
tion: CrysAlis RED; program(s) used to solve structure: SHELXS97
(Sheldrick, 1997); program(s) used to re®ne structure: SHELXL97
(Sheldrick, 1997); molecular graphics: Stereochemical Workstation
Operation Manual (Siemens, 1989) and ORTEP-3 (Farrugia, 1997);
software used to prepare material for publication: SHELXL97.
This work was supported by the Ministry of Science and
Higher Education (grant No. N204 03117 33).
Figure 3
The difference Fourier maps calculated for a model without H atoms
involved in intramolecular hydrogen bonds: (a) H1 and (b) H17. Solid
lines indicate positive values and dashed lines indicate negative values.
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: SQ3092). Services for accessing these data are
described at the back of the journal.
3
Ê
Contour level = 0.04 e A
.
Experimental
References
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C19H22N2O2
Acta Cryst. (2007). C63, o559±o561

organic compounds
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