Synthesis and crystal structures of two schiff base copper(II) complexes derived from 4-chloro-2-[(2-morpholin-4-ylethylimino)methyl]phenol

Article abstract of DOI:10.1134/S1070328410060096

A centrosymmetric mononuclear copper(II) complex, [Cu(L¹) ₂] (I), and a phenolate oxygen-bridged dinuclear copper(II) complex, [Cu₂(L²)₄] (II) (HL¹ = 4-chloro-2-[(2-morpholin-4-ylethylimino)methyl]phenol, HL² = 4-chloro-2-(cyclohexylimino-methyl)phenol), were synthesized and characterized by elemental analyses, IR, and single crystal X-ray diffraction. The crystal of I is monoclinic: space group P2₁/n, a = 13.396(3), b = 5.339(1), c = 19.740(4) A, β = 108.64(3)°, V = 1337.8(5) A³, Z = 2. The crystal of II is monoclinic: space group P2₁, a = 9.157(2), b = 22.715(4), c = 12.169(2) A, β = 95.28(3)°, V = 2520.4(8) A³, Z = 2. The Cu atom in I, lying on the inversion center, is four-coordinate in a square planar geometry with two phenolate oxygen and two imine nitrogen atoms. Each Cu atom in II is five-coordinate in a square pyramidal geometry with two phenolate oxygen and two imine nitrogen atoms from two L² ligands defining the basal plane and with one phenolate oxygen atom of another L² ligand occupying the apical position. Pleiades Publishing, Ltd., 2010.

Full text of DOI:10.1134/S1070328410060096

ISSN 1070ꢀ3284, Russian Journal of Coordination Chemistry, 2010, Vol. 36, No. 6, pp. 472–476. © Pleiades Publishing, Ltd., 2010.
Synthesis and Crystal Structures of Two Schiff Base Copper(II)
Complexes Derived from 4ꢀChloroꢀ2ꢀ[(2ꢀMorpholinꢀ4ꢀ
ylethylimino)Methyl]Phenol1
Y. L. Sang* and X. S. Lin
Department of Chemistry, Chifeng University, Chifeng 024001, P.R. China
*eꢀmail: sangyali0814@126.com
Received October 28, 2009
Abstract– I), and a phenolate oxygen–bridged
A centrosymmetric mononuclear copper(II) complex, [Cu(L1)2] (
dinuclear copper(II) complex, [Cu2(L2)4] (II) (HL1 = 4ꢀchloroꢀ2ꢀ[(2ꢀmorpholinꢀ4ꢀylethylimino)methyl]phenol,
HL2 = 4ꢀchloroꢀ2ꢀ(cyclohexyliminoꢀmethyl)phenol), were synthesized and characterized by elemental analyses,
IR, and single crystal Xꢀray diffraction. The crystal of I is monoclinic: space group
5.339(1), = 19.740(4) = 108.64(3) = 2. The crystal of II is monoclinic: space group
= 1337.8(5) Å3
= 9.157(2), = 22.715(4), = 12.169(2) = 95.28(3) = 2. The Cu atom in , lying on the
= 2520.4(8) Å3
P21/n, a = 13.396(3), b =
c
Å,
β
°
,
Å
V
,
,
Z
P21,
a
b
c
β
°
,
V
,
Z
I
inversion center, is fourꢀcoordinate in a square planar geometry with two phenolate oxygen and two imine nitrogen
atoms. Each Cu atom in II is fiveꢀcoordinate in a square pyramidal geometry with two phenolate oxygen and two
imine nitrogen atoms from two L2 ligands defining the basal plane and with one phenolate oxygen atom of another
L2 ligand occupying the apical position.
DOI: 10.1134/S1070328410060096
1
INTRODUCTION
aminoethyl)morpholine and cyclohexylamine were
obtained from Aldrich and used as received. Elemental
analyses were performed using a PerkinElmer 240C
analytical instrument. Infrared spectra were recorded
on a Nicolet 5DX FTꢀIR spectrophotometer with KBr
pellets.
Schiff bases are readily synthesized by the condenꢀ
sation reaction of carbonyl compounds with primary
amines [1, 2]. The metal complexes of Schiff bases
have been received much attention. These complexes
not only play an important role in the development of
coordination chemistry related to catalysis, enzymatic
reactions, magnetism, and molecular architectures
[3–5] but also exhibit interesting biological activities
[6–8].
Synthesis of HL1 and HL2. HL1 was prepared by reꢀ
fluxing of 5ꢀchloroꢀ2ꢀhydroxybenzaldehyde (156.6 mg,
1.0 mmol) and 4ꢀ(2ꢀaminoethyl)ꢀmorpholine (130.2 mg,
1.0 mmol) in 30 ml of methanol for 0.5 h. The clear yellow
solution was evaporated to give a yellow powder, which
was washed three times with methanol and dried in air.
The yield was 95%.
The Schiff bases 4ꢀchloroꢀ2ꢀ[(2ꢀmorpholinꢀ4ꢀ
ylethylimino)methyl]phenol (HL1) and 4ꢀchloroꢀ2ꢀ
(cyclohexyliminomethyl)phenol (HL2) are two versaꢀ
tile ligands. The complexes with HL1 have never been
reported previously. The cadmium(II), cobalt(II),
zinc(II), and nickel(II) complexes with HL2 have been
reported [9–12]. However, the copper(II) complexes
with HL2 have never been reported so far. In this paper,
a centrosymmetric mononuclear copper(II) complex,
For C13H17ClN2O2
anal. calcd., %:
Found, %:
C, 58.1;
C, 58.5;
H, 6.4;
H, 6.2;
N, 10.4.
N, 10.7.
[Cu(L1)2] (
clear copper(II) complex, [Cu2(L2)4] (II
synthesized and structurally characterized.
I)
, and a phenolate oxygenꢀbridged dinuꢀ
), have been
Ligand HL2 was prepared by a similar procedure as
that for HL1 with 4ꢀ(2ꢀaminoethyl)morpholine reꢀ
placed by cyclohexylamine (99.2 mg, 1.0 mmol). The
yield was 97%.
EXPERIMENTAL
Materials and measurements. 5ꢀChloroꢀ2ꢀhydroxyꢀ
For C13H16ClNO
benzaldehyde, 4ꢀ(2ꢀaminoethyl)morpholine, 4ꢀ(2ꢀ
anal. calcd., %:
Found, %:
C, 65.7;
C, 65.3;
H, 6.8;
H, 6.9;
N, 5.9.
N, 6.1.
1
The article is published in the original.
472

SYNTHESIS AND CRYSTAL STRUCTURES
473
Table 1. Crystallographic data and experimental details for strucꢀ Table 2. Selected bond lengths and bond angles for the
tures
I
and II
complexes
Bond
d,
Å
Bond
d, Å
Value
Parameter
I
I
II
Cu(1)–O(1)
1.880(2) Cu(1)–N(1)
II
1.885(4) Cu(1)–O(2)
2.027(6) Cu(1)–N(2)
1.892(5) Cu(2)–O(3)
2.001(6) Cu(2)–N(4)
2.015(3)
Mr
599.0
Block
1073.9
Block
Habit
Cu(1)–O(1)
Cu(1)–N(1)
Cu(2)–O(4)
Cu(2)–N(3)
1.892(4)
2.039(6)
1.904(4)
2.005(6)
Crystal size, mm
Crystal system
Space group
0.20
×
0.18
×
0.17 0.17 × 0.15 × 0.15
Monoclinic
21/
Monoclinic
21
P
n
P
a,
b,
c,
Å
Å
Å
13.396(3)
5.339(2)
19.740(4)
108.64(3)
1337.8(5)
2
9.157(2)
22.715(4)
12.169(2)
95.28(3)
Angle
ω
, deg
Angle
ω
, deg
I
O(1)Cu(1)N(1) 91.82(10)
β, deg
V, Å3
II
2520.4(8)
O(1)Cu(1)O(2) 175.0(2)
O(2)Cu(1)N(1) 89.0(2)
O(2)Cu(1)N(2) 90.7(2)
O(4)Cu(2)O(3) 160.2(2)
O(3)Cu(2)N(3) 92.5(2)
O(3)Cu(2)N(4) 90.8(2)
O(1)Cu(1)N(1) 91.2(2)
O(1)Cu(1)N(2) 90.3(2)
N(1)Cu(1)N(2) 166.1(2)
O(4)Cu(2)N(3) 92.8(2)
O(4)Cu(2)N(4) 93.8(2)
N(3)Cu(2)N(4) 150.8(2)
Z
2
1.415
ρ
,g/cm3
, mm–1
range, deg
(000)
min and Tmax
1.487
μ
1.056
1.104
θ
1.63–27.00
622
1.68–27.00
1116
F
T
0.817 and 0.841 0.834 and 0.852
Number of measured
reflections
7687
2910
1894
15333
9885
6822
solution of Cu(CH3COO)2 · H2O (20.0 mg, 0.1 mmol) in
methanol (10 ml). The mixture was stirred at room temꢀ
perature for 0.5 h and filtered. The filtrate was kept undisꢀ
turbed at room temperature for three days. Blue crystals of
II suitable for Xꢀray diffraction were obtained on the slow
evaporation of the solvent. The crystals were isolated by
filtration and dried in air. The yield was 72% based on
HL2.
Number of unique
reflections
Number of observed
reflections
Parameters/restraints
Rint
Goodnessꢀofꢀfit on F2
169/0
0.0475
1.030
595/1
0.0400
1.008
For C52H60Cl4Cu2N4O4
R
(I
≥
2
σ
(
I
))
R1 = 0.0482,
wR2 = 0.1153
R1 = 0.0650,
wR2 = 0.1574
anal. calcd., (%):
Found, (%):
C, 58.2;
C, 57.5;
H, 5.6;
H, 5.7;
N, 5.2.
N, 5.1.
R
(all data)
R1 = 0.0814,
wR2 = 0.1309
R1 = 0.0978,
wR2 = 0.1774
Xꢀray structure determination. Suitable single crysꢀ
tals with high quality of complexes and II were
selected and mounted on a Bruker Smart 1000 CCD
areaꢀdetector diffractometer with graphite monochroꢀ
Synthesis of I. A solution of HL1 (26.8 mg, 0.1 mmol)
I
in methanol (5 ml) was added with stirring to a solution of
Cu(CH3COO)2 · H2O (20.0 mg, 0.1 mmol) in methanol
(10 ml). The mixture was stirred at room temperature for
0.5 h and filtered. The filtrate was kept undisturbed at
matized Mo
K
radiation (
λ
= 0.71073 Å). Diffraction
α
data for both complexes were collected by an scan
ω
mode at 298(2) K. Data reduction and cell refinement
were performed by the SMART and SAINT programs
[13]. An empirical absorption correction was applied
by using SADABS [14]. The structures were solved by
direct methods and refined with the fullꢀmatrix leastꢀ
squares technique using the SHELXLꢀ97 package
[15]. The nonꢀhydrogen atoms in the structures were
subjected to refined anisotropic refinement. Hydrogen
atoms were located in geometrically and treated with
the riding model. Crystallographic data and experiꢀ
mental details for the complexes are summarized in
Table 1. Selected bond lengths and angles for the comꢀ
room temperature for a week. Blue crystals of I suitable for
Xꢀray diffraction were obtained on the slow evaporation of
the solvent. The crystals were isolated by filtration and
dried in air. The yield was 45% based on HL1.
For C26H32Cl2CuN4O4
anal. calcd., %:
Found, %:
C, 52.1;
C, 51.7;
H, 5.4;
H, 5.6;
N, 9.4.
N, 9.7.
Synthesis of II. A solution of HL2 (23.8 mg,
0.1 mmol) in methanol (5 ml) was added with stirring to a plexes are listed in Table 2.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 36
No. 6
2010

474
SANG, LIN
Atomic coordinates and other structural parameters of two copper(II) complexes were also synthesized
complexes
I and II have been deposited with the Cambridge
according to a similar procedure (Scheme), however,
giving different structures and II. The main differꢀ
ence between the two Schiff bases is the terminal
groups. It can be seen that the steric effect of HL1 is
larger than that of HL2, which may cause the differꢀ
ence between the structures of the two copper(II)
CrystallographicDataCenter(nos. 743838(
deposit@ccdc.cam.ac.uk or http://www.ecdc .cam.ac. uk.
I
) and 743839 (II);
I
RESULTS AND DISCUSSION
The two Schiff bases were readily synthesized
according to the similar procedure in high yields. The complexes.
O
Cl
N
O
Cl
N
N
N
+ Cu(CH3COO)2
O
Cu
O
OH
N
Cl
N
O
(
HL1
)
(I)
Cl
N
Cu
O
O
N
Cl
Cl
N
+ Cu(CH3COO)2
N
Cl
Cl
OH
O
Cu
O
N
(
HL2
)
(II)
Scheme.
The weak and broad band in the region 3300–
In centrosymmetric complex I, the Cu atom, lying
3400 cm–1 is due to the stretching vibration of the pheꢀ on the inversion center, is fourꢀcoordinate in a square
nolic OH groups of the Schiff bases. These bands are planar geometry with two phenolate oxygen and two
absent in the spectra of both the complexes indicating imine nitrogen atoms. The amine N atoms of the morꢀ
the coordination of the phenolate oxygen atoms of the pholine rings are not coordinate to the copper atom.
Schiff bases to the copper atoms. The phenolic The structure of
(C⎯ O) in the spectra of the Schiff bases are observed ously [16, 17].
I is similar to those reported previꢀ
ν
as strong bands at 1200 cm–1 for HL1 and 11203 cm–1
Complex II is a phenolate oxygenꢀbridged dinuꢀ
clear copper(II) complex, which is similar to the dinuꢀ
clear copper(II) complex with the ligand 2ꢀ(cyclohexꢀ
yliminomethyl)phenol [18]. The coordination around
each Cu atom in complex II is distorted square pyraꢀ
midal. The equatorial plane of each square pyramid is
defined by two phenolate oxygen and two imine nitroꢀ
gen atoms from two L2 ligands. The apical position of
each square pyramid is occupied by one bridging oxyꢀ
gen atom of another L2 ligand. The substantial distorꢀ
tion of each square pyramid in II is revealed by the
bond angles between apical and equatorial donor
for HL2. However, in the spectra of both the comꢀ
plexes, the bands appear at 1182 cm–1 for
I and
1185 cm–1 for II. This confirms the deprotonation and
coordination of the phenolate oxygen atoms to the
copper atoms. The strong bands at 1632 cm–1 in the
spectrum of HL1 and 1637 cm–1 in the spectrum of
HL2 are due to the azomethine groups of the Schiff
bases. These bands are shifted toward lower frequenꢀ
cies (1617 cm–1 for and 1612 cm–1 for II), indicating
I
the coordination of the azomethine nitrogen atoms to
the copper atoms. The middle bands at 287 cm–1 for
I
and 285 cm–1 for II are attributed to the Cu–N vibraꢀ
atoms, which show deviation from the ideal (90°
angle in a regular square pyramid. The basal plane of
)
tions.
Figures 1 and 2 give the perspective views of comꢀ each square pyramid is also deviated, which is shown
plexes and II, respectively. by the bond angles. The atoms Cu(1) and Cu(2) disꢀ
I
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 36
No. 6
2010

SYNTHESIS AND CRYSTAL STRUCTURES
475
C(11)
O(2)
C(10)
Cu(1)
O(1)
C(3)
N(2)
C(9)
C(8)
N(1)
C(12)
C(13)
C(2)
C(7)
C(1)
C(4)
C(6)
C(5)
Cl(1)
Fig. 1. Molecular structure of
tion (2 ꢀ , 2 – , – ).
I. Displacement is drawn at the 30% probability level. Unlabelled atoms are at the symmetry posiꢀ
x
y
z
Cl(1)
C(4)
C(5)
Cl(3)
C(51)
C(52)
C(3)
C(50)
C(30)
C(23)
C(24)
C(25)
C(31)
C(49)
C(6)
C(2)
O(1)
C(29)
C(32)
C(22)
C(1)
C(28)
O(3)
C(48)
C(26)
C(27)
C(33)
C(47)
C(21)
C(7)
N(2)
N(4)
C(46)
Cu(1)
N(1)
Cu(2)
C(20)
N(3)
C(35)
C(8)
C(14)
C(34)
O(2)
C(13)
C(39)
O(4)
C(40)
C(9)
C(15)
C(41)
C(36)
C(37)
C(12)
C(18)
C(38)
C(45)
C(16)
C(17)
C(10)
C(44)
C(42)
Cl(2)
C(11)
C(43)
Cl(4)
Fig. 2. Molecular structure of II. Displacement is drawn at the 30% probability level. Hydrogen atoms are omitted for clarity.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 36 No. 6 2010

476
SANG, LIN
2. Hui, R.ꢀH., Zhou, P., and You, Z.ꢀL., Indian J. Chem.
, 2009, vol. 48, no. 5, p. 663.
3. Lalehzari, A., Desper, J., and Levy, C.J., Inorg. Chem.
2008, vol. 47, no. 3, p. 1120.
4. Raman, N., Johnson Raja, S., and Sakthivel, A., J. Coꢀ
ord. Chem., 2009, vol. 62, no. 5, p. 691.
,
,
placed out of the corresponding leastꢀsquares planes
defined by the four equatorial donor atoms in the
direction of the apical positions by 0.089(2) and
0.082(2) Å, respectively. The Cu···Cu distance is
3.374(1) Å, which is comparable with those found in
the similar phenolate oxygenꢀbridged copper(II)
complexes [18, 19]. It is notable that the apical bonds
of the squareꢀpyramidal coordination are much longer
than those of the basal bonds, which is caused by the
hindrance effects between the two Cu(L2)2 units.
Even although the coordination geometries of the
copper atoms in I and II are different, the Cu–O and
Cu–N bonds are comparable to each other and also
comparable to those in the similar Schiff base copꢀ
A
5. Begum, M.S.A., Saha, S., Nethaji, M., and Chakravarꢀ
ty, A.R., Indian J. Chem.
6. Garnovskii, A.D., Vasilchenko, I.S., Garnovskii, D.A.,
et al., J. Coord. Chem., 2009, vol. 62, no. 2, p. 151.
7. Patel, R.N., Indian J. Chem. , 2009, vol. 48, no. 2, p. 173.
8. Refat, M.S., ElꢀDeen, I.M., Anwer, Z.M., et al., J. Coꢀ
ord. Chem., 2009, vol. 62, no. 10, p. 1709.
9. Zhang, X.ꢀL. and Li, Z.ꢀX., Chin. J. Struct. Chem.
2006, vol. 25, no. 9, p. 1067.
, A, 2009, vol. 48, no. 4, p. 473.
,
A
,
per(II) complexes. The morpholine rings in I and the
cyclohexyl rings in II adopt chair conformations.
10. Li, Z.ꢀX. and Zhang, X.ꢀL., Acta Crystallogr.
vol. 61, no. 9, p. 2806.
,
E
, 2005,
Thus, a centrosymmetric mononuclear copper(II)
complex and the phenolate oxygenꢀbridged dinuclear
copper(II) complex have been synthesized and strucꢀ
turally characterized. The Schiff bases 4ꢀchloroꢀ2ꢀ
[(2ꢀmorpholinꢀ4ꢀylethylimino)methyl]phenol and
4ꢀchloroꢀ2ꢀ(cyclohexyliminomethyl)phenol coordiꢀ
nate to the Cu atoms through the phenolate oxygen
and imine nitrogen atoms.
The phenolate oxygen atoms are potential bridging
groups. The steric effects of the terminal groups of
such Schiff bases can influence on the coordination
modes and the structures of the complexes.
11. Li, Z.ꢀX. and Zhang, X.ꢀL., Acta Crystallogr.
vol. 61, no. 9, p. m1755.
,
E
, 2005,
12. Xia, D.ꢀS., Chen, W., Zhao, Y.ꢀM., et al., Acta Crystalꢀ
logr. , 2008, vol. 64, no. 6, p. m843.
,
E
13. Smart and Saint, Area Detector Control and Integraꢀ
tion Software, Madison (WI, USA): Siemens Analytiꢀ
cal XꢀRay Systems, Inc., 1996.
14. Sheldrick, G.M., SADABS Program for Empirical Abꢀ
sorption Correction of Area Detector Data, G
(Germany): Univ. of G ttingen, 1996.
15. Sheldrick, G.M., SHELXTL Version 5.1, Software Refꢀ
erence Manual, Madison (WI, USA): Bruker AXS,
Inc., 1997.
16. Bluhm, M.E., Ciesielski, M., G
öttingen
ö
,
örls, H., et al., Inorg.
ACKNOWLEDGMENTS
Chem., 2003, vol. 42, no. 26, p. 8878.
We are very grateful to the Chifeng University for
research funding.
17. FernándezꢀG., J.M. and TepalꢀSánchez, P., Hernánꢀ
dezꢀOrtega, S., J. Mol. Struct., 2006, vol. 787, no. 1–3,
p. 1.
18. Tamura, H., Ogawa, K., Takeuchi, A., et al., Bull.
Chem. Soc. Jpn., 1979, vol. 52, no. 12, p. 3522.
REFERENCES
1. Popp, F.D. and Kirsch, W., J. Org. Chem., 1961, vol. 26, 19. Clark, G.R., Waters, J.M., Waters, T.N., et al., J. Inorg.
no. 10, p. 3858. Nucl. Chem., 1977, vol. 39, no. 11, p. 1971.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 36
No. 6
2010