A two-dimensional layer in N,N′-bis-[2-(hydroxy-meth-yl)benz-yl] ethyl-ene-diamine and a three-dimensional network in N,N′-bis-[2-(hydroxy- methyl)benz-yl]ethyl-enediammonium bis-(perchlorate)

Article abstract of DOI:10.1107/S0108270108008937

In both title compounds, C18H24N2O2, (Ia), and C18H26-N2O2 ²⁺·2ClO4 ^-, (II), respectively, the two aryl rings are strictly parallel, with an inversion centre lying at the mid-point of each central CH2 - CH2 bond. Mol-ecules in (Ia) are linked into two-dimensional layers by N - H...O hydrogen bonds. The component ions in (II) are joined together by a combination of N/O/C - H...O hydrogen bonds and C - H...π and anion...π inter-actions, forming a three-dimensional network. A structural understanding of (Ia) and (II) may provide some useful information about how and why their metal-organic complexes display various biological activities and function in catalytic processes.

Full text of DOI:10.1107/S0108270108008937

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
is described by the torsion angles C3ÐC2ÐN1ÐC1 =
72.6 (1)ꢀ, C2ÐN1ÐC1ÐC1i = 175.5 (1)ꢀ and N1ÐC1Ð
C1iÐN1i constrained by symmetry to be 180ꢀ [symmetry code:
ISSN 0108-2701
A two-dimensional layer in N,N0-bis-
[2-(hydroxymethyl)benzyl]ethylene-
diamine and a three-dimensional
network in N,N0-bis[2-(hydroxy-
methyl)benzyl]ethylenediammonium
bis(perchlorate)
Min Zhang, Xiang-Gao Meng, Zong-Qiu Hu and Xing-Man
Xu*
Chemistry Department, Central China Normal University, Wuhan 430079, People's
Republic of China
(i) x, 1 y, z], resulting in the less common gauche±trans±
trans conformation (Xia et al., 2006). The corresponding
angles in (II) are 178.9 (3), 168.1 (3) and 180ꢀ, respectively,
Correspondence e-mail: xingmanxu@mail.ccnu.edu.cn
Received 7 March 2008
Accepted 2 April 2008
Online 9 April 2008
forming the general trans±trans±trans conformation (Palladino
Ï
Â
Â
et al., 2006; Matikova-Malarova et al., 2007; Yang, Wang et al.,
2007; Yang, Han et al., 2007; Liu et al., 2007). Both N atoms in
the tetradentate ligand can be potentially coordinated to a
metal ion, according to previously reported analogues (Panda
et al., 2004; Ghosh et al., 1994), giving rise to many other
conformations. This indicates that these highly ¯exible mol-
ecules can rotate freely about all the ꢁ bonds. However, when
(II) is coordinated to a metal ion, it should ®rst be
deprotonated using a moderately basic medium.
In both title compounds, C18H24N2O2, (Ia), and C18H26-
2+
N2O2 Á2ClO4 , (II), respectively, the two aryl rings are
strictly parallel, with an inversion centre lying at the mid-point
of each central CH2ÐCH2 bond. Molecules in (Ia) are linked
into two-dimensional layers by NÐHÁ Á ÁO hydrogen bonds.
The component ions in (II) are joined together by a
combination of N/O/CÐHÁ Á ÁO hydrogen bonds and CÐ
HÁ Á Áꢀ and anionÁ Á Áꢀ interactions, forming a three-dimen-
sional network. A structural understanding of (Ia) and (II)
may provide some useful information about how and why
their metal±organic complexes display various biological
activities and function in catalytic processes.
Although a similar C(7) motif (Bernstein et al., 1995) exists
in both compounds, in (Ia) it is formed by intramolecular O1Ð
H1EÁ Á ÁN1 hydrogen bonds and in (II) by N1ÐH1CÁ Á ÁO1
hydrogen bonds. In order to investigate further the reason for
this, the hydrogen-bonding energy and total molecular energy
of the two practical and one posulated conformation were
calculated according to our earlier method (Hu et al., 1999;
Hu, 1998) using the program GAUSSIAN03W (Frisch et al.,
2004) at the RB3LYP/6-31G(d) level. It can be seen from
Comment
In recent decades, tetradentate Schiff bases known generally
as salenH2 (Kahwa et al., 1986) have been studied extensively
owing to their potential biological activities, e.g. antibacterial,
antitumour (Santos et al., 2001; Viswanathan et al., 1998;
Â
Garcõa-Zarracino et al., 2002) and catalytic (Mohebbi et al.,
2005). They not only offer greater ¯exibility than the corre-
sponding Schiff bases, but also adopt two additional sites
capable of ꢁ-bonding which should be helpful in designing
new useful inorganic complexes (Atwood & Rutherford, 1995;
Xu et al., 2004; Tinoco et al., 2007). In order to gain more
insight into these analogues, we have synthesized a new
tetradentate ligand, (Ia), containing an N2O2 donor set, and its
diammonium bis(perchlorate), (II), and we report here the
molecular and supramolecular structures.
Figure 1
The molecular structure of (Ia), showing the atom-numbering scheme.
Displacement ellipsoids are drawn at the 50% probability level. Some
hydrogen bonds are shown as dashed lines. [Symmetry codes: (i) x, 1 y,
z.]
Both title compounds crystallize in the space group P21/c,
with one-half of the molecule representing the asymmetric
unit (Fig. 1). The conformation of the central chain in (Ia)
o272 # 2008 International Union of Crystallography
DOI: 10.1107/S0108270108008937
Acta Cryst. (2008). C64, o272±o275

organic compounds
Table 1 that the dication has the lowest total molecular energy
and the postulated form (Ib) has the highest. The Mulliken
charges on the N atoms in (Ia) and (Ib) are 0.594 and
0.569, respectively. This indicates that the neutral N atoms in
(Ia) may be more easily protonated than those in (Ib). We also
have found that when Lewis acids are absent, the neutral
molecules preferentially adopt conformation (Ia). Some
contrast experiments have been carried out by displacing the
solvent with ethanol, acetone and water. However, no crystals
adopting conformation (Ib) were obtained.
hydrogen-bond donor via atom H1C to hydroxyl atom O1 in
the molecule at ( x, 12 + y, 21 z), forming a one-dimensional
C(7) chain running parallel to the [010] direction, which is
generated by the 21 screw axis at (0, y, 14). Adjacent C(7) chains
related by the inversion centre at the mid-point of the CH2Ð
CH2 unit thus link the molecules into two-dimensional layers
(Fig. 2) running parallel to the (100) plane. There are two
halves of such a layer passing through the unit cell, with the
reference layer in the domain 0.474 < x < 0.474 and the other
in the domain 0.526 < x < 1.474. No CÐHÁ Á Áꢀ or ꢀ±ꢀ stacking
interactions are observed between adjacent layers.
In the crystal structure of (II), the component ions are
linked into a three-dimensional network by a combination of
N/O/CÐHÁ Á ÁO hydrogen bonds and CÐHÁ Á Áꢀ and anionÁ Á Áꢀ
interactions, which can be readily analyzed in terms of two
simple substructures. First, the combined actions of ®ve inter-
ion hydrogen bonds (Table 2) and their respective equivalents
result in two-dimensional layers running parallel to the (100)
plane. The reference two-dimensional layer lies within the
domain 0.065 < x < 1.065 and there is only one such layer
passing through the unit cell (Fig. 3). Analysis by PLATON
In the crystal structure of (Ia), the molecules are linked by
means of NÐHÁ Á ÁO hydrogen bonds into two-dimensional
layers. Amino atom N1 in the molecule at (x, y, z) acts as a
Figure 2
The molecular structure of (II), showing the atom-numbering scheme.
Displacement ellipsoids are drawn at the 50% probability level. Some
hydrogen bonds are shown as dashed lines. [Symmetry codes: (ii) 1 x,
Figure 4
Part of the crystal structure of (II), showing the formation of the two-
dimensional network running parallel to the (100) plane. Hydrogen bonds
are shown as dashed lines.
1
y, 1 z.]
Figure 5
Part of the crystal structure of (II), showing the formation of the two-
dimensional network running parallel to the (102) plane built up from
CÐHÁ Á Áꢀ interactions. Hydrogen bonds are shown as dashed lines. For
the sake of clarity, H atoms and perchlorate anions not involved in the
motif have been omitted.
Figure 3
Part of the crystal structure of (Ia), showing the formation of the two-
dimensional network running parallel to the (100) plane. Hydrogen bonds
are shown as dashed lines.
2+
C18H24N2O2 and C18H26N2O2 Á2ClO4
ꢁ
Acta Cryst. (2008). C64, o272±o275
Zhang et al.
o273

organic compounds
Compound (II)
(Spek, 2003) indicates that a rather weak anionÁ Á Áꢀ inter-
action exists within the two-dimensional layer formed between
the perchlorate anion at (x, y, z) and the C3±C8 benzene ring
Crystal data
2+
C18H26N2O2 Á2ClO4
3
Ê
V = 1090.11 (19) A
Ê
at (x, y 1, z) [O3Á Á ÁCg1 = 3.849 (6) A and Cl1ÐO3Á Á ÁCg1 =
Mr = 501.31
Monoclinic, P21=c
Z = 2
Mo Kꢃ radiation
117.5 (3)ꢀ; Cg1 denotes the centroid of the C3±C8 ring].
Secondly, neighbouring layers are interlinked by weak CÐ
HÁ Á Áꢀ interactions (Table 2) into a three-dimensional
network. In more detail, aromatic atom C7 in the molecule at
(x, y, z) acts as donor to the benzene ring at (2 x, 12 + y, 23 z),
so producing a two-dimensional layer parallel to the (102)
plane generated by co-operative action between the 21 screw
axis and the inversion centre (Fig. 4). These two types of (100)
and (102) layers are joined together to form a three-dimen-
sional network in (II).
1
Ê
a = 12.8926 (12) A
ꢄ = 0.36 mm
T = 294 (2) K
Ê
b = 5.8332 (6) A
Ê
c = 15.1397 (15) A
0.20 Â 0.10 Â 0.06 mm
ꢂ = 106.779 (2)ꢀ
Data collection
Bruker SMART APEX CCD area-
detector diffractometer
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
Tmin = 0.931, Tmax = 0.983
8763 measured re¯ections
2133 independent re¯ections
1806 re¯ections with I > 2ꢁ(I)
Rint = 0.035
Re®nement
In summary, the crystal structures of a ligand with an N2O2
donor set and its ammonium perchlorate have been reported.
In (Ia), the neutral molecules are linked into a two-dimen-
sional layer. The component ions in (II) are joined together,
forming a three-dimensional network. Further research on the
synthesis of metal±organic complexes containing the ligand
and their potential application is underway in our laboratory.
R[F2 > 2ꢁ(F2)] = 0.060
wR(F2) = 0.164
S = 1.05
2133 re¯ections
151 parameters
H atoms treated by a mixture of
independent and constrained
re®nement
3
Ê
Áꢅmax = 0.46 e A
3
Ê
0.36 e A
Áꢅmin
=
Table 1
Comparison of intramolecular hydrogen-bond energy and total molecular
energy (kJ mol 1).
Compound
Intramolecular
hydrogen-bond
energy
Total molecular
energy
Experimental
All reagents and solvents were used as obtained without further
puri®cation. A mixture of ethylenediamine (2 g, 0.03 mol) and
2-(hydroxymethyl)benzaldehyde (8 g, 0.06 mol) was stirred at 348 K
for 10 h, and the resulting white precipitate was removed by ®ltration
and dried in a vacuum. The white precipitate (4 g, 0.013 mol), LiAlH4
(1 g, 0.026 mol) and THF (50 ml) were stirred at 333 K for 6 h. The
solvent was removed by rotary evaporation to yield 6.7 g of a powder.
Plate-shaped colourless crystals of (Ia) suitable for single-crystal
X-ray diffraction analysis were grown by slow evaporation of a
methanol solution (10 ml) at room temperature. To prepare
compound (II), the powder of (Ia) (2 g) was dissolved in methanol
(15 ml, adjusted to pH 5 using HClO4). Block-shaped colourless
crystals of (II) were obtained by slow evaporation of the solvent over
a period of several days.
(Ia)
(Ib)
(II)
29.71
15.27
92.74
92653.84
92652.01
92720.10
Table 2
Hydrogen-bond geometry for compounds (Ia) and (II) (A, ).
ꢀ
Ê
Cg1 is the centroid of the C3±C8 ring of (II).
DÐHÁ Á ÁA
DÐH
HÁ Á ÁA
DÁ Á ÁA
DÐHÁ Á ÁA
(Ia)
O1ÐH1EÁ Á ÁN1
0.92 (2)
0.883 (17)
1.86 (2)
2.366 (17)
2.7461 (16)
3.2042 (15)
161 (2)
159 (1)
N1ÐH1CÁ Á ÁO1iii
(II)
O1ÐH1EÁ Á ÁO4iv
C9ÐH9AÁ Á ÁO3v
N1ÐH1CÁ Á ÁO1
N1ÐH1DÁ Á ÁO2
C1ÐH1BÁ Á ÁO5
C7ÐH7Á Á ÁCg1vi
0.81 (4)
0.97
0.832 (19)
0.856 (18)
0.97
2.57 (4)
2.53
2.09 (3)
2.39 (4)
2.53
3.118 (5)
3.487 (5)
2.788 (4)
3.008 (5)
3.302 (4)
3.434 (3)
126 (4)
168
142 (3)
129 (3)
137
Compound (Ia)
Crystal data
3
Ê
C18H24N2O2
Mr = 300.39
Monoclinic, P21=c
Ê
a = 14.0939 (2) A
V = 838.13 (10) A
Z = 2
0.93
2.70
136
Mo Kꢃ radiation
1
1
2
z ‡ 12; (iv) x; y ‡ 23 ; z ‡ 21; (v) x; y ‡ 21 ; z ‡ 12; (vi)
ꢄ = 0.08 mm
T = 294 (2) K
Symmetry codes: (iii) x; y ‡
;
x; 12 ‡ y; 32 z.
Ê
b = 6.9520 (6) A
2
Ê
c = 8.6661 (7) A
0.30 Â 0.15 Â 0.04 mm
ꢂ = 99.226 (3)ꢀ
For both compounds, H atoms bonded to C atoms were positioned
Data collection
Ê
geometrically, with CÐH = 0.93 (aromatic) or 0.97 A (methylene),
and re®ned as riding, with Uiso(H) = 1.2Ueq(C). H atoms bonded to N
and O atoms were found in difference Fourier maps, with NÐH and
Bruker SMART APEX CCD area-
detector diffractometer
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
Tmin = 0.947, Tmax = 0.996
6213 measured re¯ections
1645 independent re¯ections
1314 re¯ections with I > 2ꢁ(I)
Rint = 0.025
Ê
OÐH distances re®ned freely [NÐH = 0.83(2)±0.88(2)A and OÐH =
Ê
0.81 (4)±0.92 (2) A] and with Uiso(H) = 1.2Ueq(N) or 1.5Ueq(O).
For both compounds, data collection: SMART (Bruker, 2001); cell
re®nement: SMART; data reduction: SAINT-Plus (Bruker, 2001);
program(s) used to solve structure: SHELXS97 (Sheldrick, 2008);
program(s) used to re®ne structure: SHELXL97 (Sheldrick, 2008);
molecular graphics: PLATON (Spek, 2003); software used to prepare
material for publication: PLATON.
Re®nement
R[F2 > 2ꢁ(F2)] = 0.049
wR(F2) = 0.143
S = 1.11
1645 re¯ections
106 parameters
H atoms treated by a mixture of
independent and constrained
re®nement
3
Ê
Áꢅmax = 0.21 e A
3
Ê
0.15 e A
Áꢅmin
=
2+
ꢁ
o274 Zhang et al. C18H24N2O2 and C18H26N2O2 Á2ClO4
Acta Cryst. (2008). C64, o272±o275

organic compounds
Kahwa, I. A., Selbin, J., Hsieh, T. C.-Y. & Laine, R. A. (1986). Inorg. Chim.
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This work received ®nancial support mainly from the Key
Fundamental Project (grant No. 2002CCA00500).
Liu, Y.-F., Xia, H.-T., Wang, D.-Q., Yang, S.-P. & Meng, Y.-L. (2007). Acta
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Ï
Matikova-Malarova, M., Sebela, M. & Travnõcek, Z. (2007). Acta Cryst. E63,
Æ
Â
o1753±o1755.
Â
Â
ÂÏ
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: AV3145). Services for accessing these data are
described at the back of the journal.
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2+
C18H24N2O2 and C18H26N2O2 Á2ClO4
ꢁ
Acta Cryst. (2008). C64, o272±o275
Zhang et al.
o275