Synthesis and crystal structures of two new Schiff base cobalt(II) and nickel(II) complexes

Article abstract of DOI:10.1134/S1070328412120019

The Schiff base ligand (HL) obtained from phenylmethanamine and 5-methoxysalicylaldehyde are used as ligands for Co(II) and Ni(II) resulting in complexes [Co(L)₂] (I) and [Ni(L)₂] (II), and their solid state structures were determine

Full text of DOI:10.1134/S1070328412120019

ISSN 1070ꢀ3284, Russian Journal of Coordination Chemistry, 2013, Vol. 39, No. 1, pp. 134–140. © Pleiades Publishing, Ltd., 2013.
Synthesis and Crystal Structures of Two New Schiff Base Cobalt(II)
and Nickel(II) Complexes1
Y. Gou, Y. Liu, X. H. Zhao, Y. G. Li*, and W. Chen*
School of Textile Engineering, School of Chemistry and Chemical Engineering, Wuhan Textile University,
Wuhan, 430073 P.R. China
*eꢀmail: liyg2010@wtu.edu.cn; chenwu050@yahoo com.cn
Received June 23, 2011
Abstract
are used as ligands for Co(II) and Ni(II) resulting in complexes [Co(L)2] (
state structures were determined by Xꢀray crystallography. In both complexes, weak interactions play an
important role in the molecular selfꢀassembly. Complex was stacked up to the 2D layers by C–H⋅⋅⋅O hydroꢀ
—
The Schiff base ligand (HL) obtained from phenylmethanamine and 5ꢀmethoxysalicylaldehyde
I
) and [Ni(L)2] (II), and their solid
I
gen bonds and C–H⋅⋅⋅π interactions. In contrast, complex II was extended into 2D sheet by C–H⋅⋅⋅O hydroꢀ
gen bonds, the C–H⋅⋅⋅π interactions, and edgeꢀtoꢀface interactions.
DOI: 10.1134/S1070328412120019
1
INTRODUCTION
N,O,Oꢀdonor ligand [28], and so on, to yield multiꢀ
dimensional complexes [29, 30].
The current interest in the transition metal comꢀ
In order to obtain novel Schiff base cobalt(II) and
nickel(II) complexes, in this paper, the Schiffꢀbase
ligand HL was prepared by the reaction of phenylꢀ
methanamine with 5ꢀmethoxysalicylaldehyde. The
ligand HL has two significant features. First, the O atꢀ
oms of 5ꢀmethoxysalicylaldehyde is a hydrogenꢀ
bonding synthon. Potential hydrogenꢀbond accepꢀ
tors are common in supramolecular systems. They
are either an increase in dimensionality or the modiꢀ
fication of the polymer without changing its dimenꢀ
sionality in coordination polymers [31]. Second, it
plexes of Schiff base ligands is rapidly expanding beꢀ
cause of their applications in biological activities
[1, 2], antifertility and enzymatic activity [3], catalysis
[4, 5], dyes [6], and herbicidal applications [7], as well
as their intriguing variety of topologies and architecꢀ
tures [8–11]. It is well known that biological function
of cobalt is its involvement in the coenzyme related to
vitamin B12 [12–15] and nickel is an essential element
of life by being present in a number of enzymes
[16, 17]. Moreover, architectural control of molecular
selfꢀorganization is of great importance for the develꢀ
opment of functional materials [18–20]. In the crystal
engineering, supramolecular metal–organic architecꢀ
tures assembled through coordination bonds as well as
other weak cooperative interactions, such as Hꢀbonding,
contains two aromatic rings could form
tions and C–H⋅⋅⋅π interactions. Herein, the cobalt(II)
π
–π interacꢀ
and nickel(II) complexes of the Schiff base ligand HL,
[Co(L)2] (I) and [Ni(L)2] (II), were reported.
π
–π interactions and C–H⋅⋅⋅π interactions. Among
these intermolecular weak forces, the Hꢀbonding is arꢀ
guably the most powerful organizing element in the
EXPERIMENTAL
Materials and measurements. 5ꢀMethoxysalicylalꢀ
dehyde and phenylmethanamine were purchased from
Aldrich and used without further purication. Elemenꢀ
tal analysis for C, H, and N was carried out on a Perkꢀ
inElmer 2400 analyzer. Xꢀray crystallography was carꢀ
ried out using a Bruker SMART APEX II CCD difꢀ
fractometer.
design of supramolecular systems [21, 22]. The
π–π
interactions are important noncovalent intermolecuꢀ
lar forces which can contribute to selfꢀassembly or
molecular recognition processes when extended strucꢀ
tures are formed from building blocks with aromatic
moieties [23–25]. The C–H⋅⋅⋅π interactions are also
important noncovalent intermolecular forces similar
Synthesis of complex I. 5ꢀMethoxysalicylaldehyde
to
π
– interactions. In addition, Schiff base ligands (0.30 g, 2 mmol) and phenylmethanamine (0.21 g,
π
2 mmol) were dissolved in an aqueous methanol soluꢀ
tion (15 mL) and stirred 1 h to give an orange solution,
which was added to a methanol solution (15 mL) of
which usually contain O,Nꢀdonor atoms have played
an important role in coordination chemistry, such as
may act as a bidentate N,Oꢀ [26, 27] and tridentate
Co(NO3)2
⋅
6H2O (0.29 g, 1 mmol). The mixture was
1
The article is published in the original.
stirred for another 30 min at room temperature to give
134

SYNTHESIS AND CRYSTAL STRUCTURES OF TWO NEW SCHIFF BASE
135
Table 1. Crystallographic parameters and summary of data collection for structures
I
and II
Value
Parameter
I
II
Molecular weight
Crystal system
Space group
539.47
539.25
Monoclinic
Monoclinic
C
2/c
P21/
c
Crystal size, mm
0.27
×
0.23
×
0.20
0.26
×
0.21
×
0.20
a
,
Å
Å
Å
27.394(3)
5.6080(6)
18.603(2)
116.107(2)
298(2)
13.5152(6)
10.9051(5)
18.3759(9)
111.58
b
,
c
,
β
, deg
, K
Å3
T
298(2)
V
,
2566.3(5)
4
2518.6(2)
4
Z
ρcalcd, gm–3
(000)
(Mo
1.396
1.422
F
1124
1128
μ
K
), mm–1
0.708
0.810
α
Scan mode
Multiscan
Multiscan
Index ranges
h,
k
,
l
–33
≤
h
≤
33, –6
≤
k
≤
6, –22
≤
l
≤
22 –16
≤
h
≤
16, –13
≤
k
≤
13, –22
≤
l ≤ 22
Reflections collected
2449
4964
Independent reflections (Rint
)
12348 (0.0464)
2164
25904 (0.0399)
4224
Observed data,
I
> 2σ(I)
Parameters
169
336
Goodnessꢀofꢀfit on F 2
Final indices ( > 2
indices (all data)
Δρmin Δρmax
Å–3
1.030
1.006
R
I
σ(I
))
R
1 = 0.0800
R1 = 0.0400
R
wR2 = 0.1736
wR2 = 0.0965
/
,
e
0.558, –0.444
0.354, –0.210
a celadon solution and then filtered. The filtrate was The mixture was stirred for another 30 min at room
kept in air for a week, forming red block crystals. The temperature to give a celadon solution and then filꢀ
crystals were isolated, washed three times with distilled tered. The filtrate was kept in air for a week, forming
water and dried in a vacuum desiccator containing anꢀ black block crystals. The crystals were isolated, washed
hydrous CaCl2. The yield was 75%.
three times with distilled water and dried in a vacuum
desiccator containing anhydrous CaCl2. The yield was
68%.
For C30H28N2O4Co
anal. calcd., %: C, 66.79;
Found, %: C, 66.62;
H, 5.23;
H, 5.34;
N, 5.19.
N, 5.10.
For C30H28N2O4Ni
anal. calcd., %: C, 66.82;
Found, %: C, 66.70;
H, 5.23;
H, 5.14;
N, 5.19.
N, 5.10.
Synthesis of complex II. 5ꢀMethoxysalicylaldehyde
(0.30 g, 2 mmol) and phenylmethanamine (0.21 g,
2 mmol) were dissolved in an aqueous methanol soluꢀ
Xꢀray structure determinations [32]. For complexes
I
tion (15 mL). The mixture was stirred for 1 h to give an and II, the Xꢀray crystallographic data were collected
orange solution, which was added to a methanol soluꢀ on a Bruker SMART Apex II CCD diffractometer usꢀ
tion (15 mL) of Ni(NO3)2
⋅
6H2O (0.29 g, 1 mmol). ing graphiteꢀmonochromated Mo
K
(λ = 0.71073 Å)
α
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136
GOU et al.
Table 2. Selected bond distances (Å) and angles (deg) for I* and II
Bond
d,
Å
Bond
d,
Å
Δ
**
I
II
Co(1)–O(1)
Co(1)–N(1)
N(1)–C(7)
N(1)–C(9)
1.922(3)
2.003(4)
1.296(6)
1.451(6)
Ni(1)–O(1)
Ni(1)–O(3)
Ni(1)–N(1)
Ni(1)–N(2)
N(1)–C(7)
N(1)–C(9)
1.8333(14)
1.8292(15)
1.9214(16)
1.9227(16)
1.300(2)
0.0887
0.0928
0.0816
0.0803
–0.004
–0.024
1.475(2)
Angle
ω
, deg
Angle
ω
, deg
Δ
**
I
II
O(1)Co(1)N(1)
O(1)Co(1)N(1)i
O(1)Co(1)O(1)i
N(1)Co(1)N(1)i
93.70(14)
123.80(14)
110.188(15)
114.304(15)
O(3)Ni(1)N(2)
O(1)Ni(1)N(1)
O(3)Ni(1)N(1)
O(1)Ni(1)N(2)
O(3)Ni(1)O(1)
N(2)Ni(1)N(1)
93.38(6)
93.45(6)
0.32
0.25
86.32(6)
37.48
87.05(6)
36.75
176.392(7)
176.601(8)
–66.204
–62.297
i
* Symmetry code: 2 –
x,
y, 1.5 –
z.
**
Δ
is the difference of the values between complexes I and II.
radiation. The collected data were reduced using the
(II); deposit@ccdc.cam.ac.uk or http://www.ccdc.
SAINT program, and empirical absorption correcꢀ cam.ac.uk).
tions were performed using the SADABS program.
The structures were solved by direct methods and reꢀ
fined against F2 by fullꢀmatrix leastꢀsquares methods
using the SHELXTL, version 5.1. All of the nonꢀhyꢀ
drogen atoms were refined anisotropically. All other
hydrogen atoms were placed in geometrically ideal poꢀ
sitions and constrained to ride on their parent atoms.
RESULTS AND DISCUSSION
The Schiff base ligand HL in this paper was preꢀ
pared by reaction of phenylmethanamine with
5ꢀmethoxysalicylaldehyde, in 83% yield in an absolute
MeOH solution. Ligand HL is the yellow crystallite,
stable compound in air at room temperature. It is easꢀ
ily soluble in common polar organic solvents, such as
The crystallographic data for compounds
summarized in Table 1. Selected bond lengths and anꢀ
gles are given in Table 2.
Supplementary material for complexes
has been deposited with the Cambridge Crystalloꢀ
graphic Data Centre (nos. 830984 ( ) and 830985
I and II are
MeCN, MeOH, and EtOH, etc
were obtained from reaction of the Schiff base ligand
HL with Co(NO3)2 6H2O and Ni(NO3)2 6H2O in
methanol, respectively. The elemental analysis is in
good agreement with the chemical formula proposed
for complexes and II
. Complexes I and II
I
and II
⋅
⋅
I
I
.
Table 3. Geometric parameters of hydrogen bonds for
Distance,
D–H ⋅⋅⋅
I
and II
*
In , the Co(II) atom is fourꢀcoordinated by two
I
Å
N atoms and two O atoms from two bidentate ligands
HL in the usual trans arrangement (Fig. 1a). Analoꢀ
gous tetrahedral Co(II) species were previously reꢀ
ported in [33–37]. The bond distances of Co(1)–O(1)
Angle
DHA, deg
Contact D–H⋅⋅⋅
A
H
A
D A
⋅⋅⋅
I
C(12)–H(12)⋅⋅⋅O(2)i 0.93 2.66 3.593(3)
177
157
and Co(1)–N(1) are 1.922(3) and 2.003(4)
tively, which are significantly longer than those obꢀ
served in other complexes with bidentate Schiffꢀbase
ligands (1.826(2) and 1.926(2) ) [33] and comparable
to those in the similar Co(II) coordination
modes (1.892(2)–1.935(2) and 1.963(2)–2.009(2)
Å, respecꢀ
II
C(6)ii–H(6)⋅⋅⋅O(3)
0.93 2.72 3.596(3)
ii
Å
i
* Symmetry codes: 2 –
x,
y, 1.5 –
z
for
I
;
1 –
x, 0.5 +
y, 1.5 –
z
for II
.
Å
)
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 39
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SYNTHESIS AND CRYSTAL STRUCTURES OF TWO NEW SCHIFF BASE
137
C(5)
(a)
C(6)
O(2)
C(14)
C(15)
C(1)
C(7)
C(13)
C(4)
C(9)
N(1)
C(8)
C(12)
C(10)
C(3)
C(11)
C(2)
O(1)
Co(1)
i
O(1)
i
N(1)
i
O(2)
(b)
O(2)
i
C(12)
iii
C(12)
ii
O(2)
(c)
y
x
z
i
C(8)
C(8)
3.7688
3.7688
(d)
Fig. 1. Molecular structure of complex
I
(symmetry code: (i) 2 –
, 0.5 –
built up by symmetry operations 2 –
(c) and a view of a twoꢀdimensional sheet of formed by interaction of the C–H⋅⋅⋅O hydrogen bonds and C–H⋅⋅⋅π
interactions. Hydrogen atoms were omitted for clarity (d).
x
,
y
y
, 1.5 –
, –0.5 +
z
) (a); hydrogen bonds (dash lines) between the moꢀ
; (ii) 1.5 – , 0.5 – , 1 – ; (iii) 2 – , 1.5 –
, 1.5 – ; 2 – , –1 + , 1.5 –
lecular structures of complex
(b); a view of C–H⋅⋅⋅π interactions (dash lines) in
1 +
I
(symmetry codes: (i) –0.5 +
x
z
x
x
y
z
x,
y
y
z)
z;
I
,
y
z
x
x,
⎯
y,
z
I
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 39
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138
GOU et al.
C(5)
(a)
C(6)
C(1)
O(2)
C(14)
C(13)
C(15)
C(9)
C(7)
N(1)
C(4)
C(3)
C(8)
C(12)
C(10)
C(2)
O(1)
C(11)
Ni(1)
O(3)
N(2)
O(4)
(b)
C(6)
O(3)
O(3)
ii
i
C(6)
(c)
C(9)
3.3469
3.3469
i
C(9)
y
x
z
Fig. 2. Molecular structure of complex II (a); 1D zigzag chain assembled via C–H⋅⋅⋅O hydrogen bonds in II. Symmetry code:
(i) 1 – , 0.5 + , 1.5 – ; (ii) 1 – , –0.5 + , 1.5 – (b); a view of C–H⋅⋅⋅π interactions in II built up by symmetry operation
, – , 2 – (c); the edgeꢀtoꢀface interactions in the neighboring molecules of II. Hydrogen atoms were omitted for clarity
(d); a view of a 2D sheet in II formed by the C–H⋅⋅⋅O hydrogen bonds interactions, C–H⋅⋅⋅π interactions and edgeꢀtoꢀface inꢀ
teractions. Hydrogen atoms were omitted for clarity (e).
x
y
y
z
z
x
y
z
1
⎯
x
[34–37]. The angles subtended at the Co2+ ion in the
distortedꢀtetrahedral geometry (CoN2O2) is in the
the C⋅⋅⋅O distance in C–H⋅⋅⋅O hydrogen bond is in
the range of 3.0–4.0 . The C–H⋅⋅⋅O angle in the
range of 110 –180 is acceptable, although a linear
C–H⋅⋅⋅O bond (150 < 180 ) is structurally
more important. In
, the C(12)⋅⋅⋅O(2)i distance of
3.593(7) inꢀ
and C(12)–H(12)⋅⋅⋅O(2)i angle of 177
dicate an effective C–H⋅⋅⋅O hydrogen bond. In fact,
dimensional C–H⋅⋅⋅O hydrogen bond interactions such long C–H⋅⋅⋅O hydrogen bonds have also been
between the adjacent [Co(L)2] molecules (Fig. 1b,
Table 3). Desiraju studies [38] have revealed that C–H⋅⋅⋅π interactions are also apparent in
Å
θ
°
°
range from 93.70(14)
tween two sixꢀmembered chelate planes was 79.6(9)
addition, the benzene rings of the Schiff base ligand were
twisted, at an angle of 84.19 with respect to each other.
It should be noted that there are persistent oneꢀ
°
to 123.80(14)°. The angle beꢀ
°
<
θ
°
°. In
I
°
Å
°
observed in the literature before [39–41]. In addition,
I. C–H⋅⋅⋅π
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 39
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SYNTHESIS AND CRYSTAL STRUCTURES OF TWO NEW SCHIFF BASE
139
(d)
4.6869
x
y
z
(e)
x
z
y
Fig. 2. (Contd.)
interactions can be depicted by the distance nated by two N atom and two O atoms from two Schiff
< 4.3 ) between the donor carbon atom and the
centre of the acceptor ring; the distance ( < 3.4 ) beꢀ
tween the H of donor carbon atom and the centre of
the acceptor ring ; the angle ( < 25 ) between the ring
normal and a vector connecting the methyl carbon atꢀ
om and the centre of the ring; and the angle ( > 120
(D
Å
base ligands HL, which affords a planar trans
ꢀ
d
Å
[NiN2O2] coordination geometry (Fig. 2a). Analogous
tetrahedral Ni(II) species were previously reported in
[44–48]. In II, the Ni(1)–O(1) bond distance of
θ
°
1.8333(14)
1.8292(14)
Å
Å
is slightly longer than that of Ni(1)–O(3)
. The Ni–O bond distances are smaller
ϕ
°
)
between the C–H and ring centreꢀH vectors [42, 43].
The C(8) atom forms a close contact with an aromatic
ring (the ring defined by C(1)⋅⋅⋅C(6) atoms) of an adꢀ
than that of 1.905(3)
complexes [44] and comparable to those in the similar
Ni(II) coordination modes (1.804–1.847 ) [45–48].
The Ni(1)–N(2) bond distance of 1.9227(16) is
slightly longer than that of Ni(1) N(1) 1.9214(16)
which is significantly smaller than those observed in
other analogous complexes [44]. The angles subtended
at the Ni2+ ion in the planar geometry (NiN2O2) are in
Å observed in other analogous
Å
jacent molecule (
D
= 3.7688
Å
,
d
= 2.8631
Å
,
θ
< 18
°
,
Å
ϕ
= 157.667 ) indicate a strong C–H⋅⋅⋅π interaction
°
⎯
Å,
and the adjacent molecules were connected through
intermolecular C–H⋅⋅⋅π interactions (Fig. 1c). Toꢀ
gether with the C–H⋅⋅⋅O hydrogen bonds, the
⋅⋅⋅π interactions link the molecules of complex
into a 2D layered structure as shown in Fig. 1d.
C
⎯
H
I
the range of 86.32(6)°–93.45(6)° and 176.392(7)
°–
176.601(8)°. It is interesting to point out that two sixꢀ
In contrast to I, the Ni(II) atom lies on a crystalloꢀ
graphic inversion centre. Nickel atom is fourꢀcoordiꢀ membered chelate planes were twisted by 5.74(4)
°
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 39
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140
GOU et al.
16. Mobley, H.L
.
1989, vol. 53, p. 85.
and Hausinger, R.P., Microbiol. Rev.
,
,
with respect to each other, which are significantly
smaller than complex
There were several significantly weak interactions
in II. Firstly, there was a kind of C–H⋅⋅⋅O hydrogenꢀ
bonding interactions between the adjacent molecules
of II (Fig. 2b). The H(6)⋅⋅⋅O(3) distance was 2.72
with a corresponding O⋅⋅⋅C separation of 3.596(3)
The angle C–H⋅⋅⋅O was 157
of this interaction as a linear hydrogen bond [38]. Secꢀ
ondly, one C(9) atom of the amine was also able to inꢀ
teract with the aromatic ring (the ring defined by
C(16)⋅⋅⋅C(21) atoms) of an adjacent molecule (
3.3469 = 2.6786 < 18 = 126.416
(Fig. 2c) [42, 43]. What’s more, compared with , the
unusual feature of II is the existing edgeꢀtoꢀface interꢀ
actions. These energetically favorable nonbonded
edgeꢀtoꢀface interactions can be defined formally as
those pairs with phenyl ring centroid separations >4.5
and <7 and dihedral angles within 30 of 90 [49].
Here, the centroid–centroid distances were 4.687
(Fig. 2d), and at the lower end of the range (4.5–7.0
I.
17. Jabri, E., Karr, M.B., Hausinger, R.P., et al., Science
1995, vol. 268, p. 998.
18. Braga, D., Grepioni, F., and Desiraju, G.R., Chem.
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19. Balzani, V., Credi, A., Raymo, F.M., et al., Angew.
Å
Å.
Chem. Int. Ed., 2000, vol. 39, p. 3348.
°
, leading to a description 20. Swiegers, G.F
.
vol. 100, p. 3483.
and Malefetse, T.J., Chem. Rev., 2000,
21. Desiraju, G.R., Acc. Chem. Res., 2002, vol. 35, p. 565.
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vol. 95, p. 2725.
D =
Å
,
d
Å
,
θ
°,
ϕ
°
)
24. Claessens, C.G
1997, vol. 10, p. 254.
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I
,
,
Å
á
ález, J.M., and Gárateꢀ
Å
°
°
Å
.
Å
)
and the dihedral angles were 60.247(7) . Together with
°
29. Bermejo, M.R., GonzalezꢀNoya, A.M., Abad, V.,
et al., Eur. J. Inorg. Chem., 2004, p. 3696.
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Inorg. Chem., 2005, p. 2376.
31. Cordes, D.B., Hanton, L.R., and Spicer, M.D., Inorg.
the C(6)i–H(6)⋅⋅⋅O(3) interactions and the C–H⋅⋅⋅π
interactions, the edgeꢀtoꢀface interactions extend the
molecular structures of II into the 2D sheet (Fig. 2e).
Chem., 2006, vol. 45, p. 7651.
ACKNOWLEDGMENTS
32. SMART (version 5.0), SAINT (version 6), SHELXTL
(version 6.1), and SADABS (version 2.03), Madison
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This work was financially supported by the Hubei
National Science Foundation (no. 2009CDA022),
and the Education Office of Hubei Province
(nos. D20091704 & Q20101610).
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2013