Synthesis, crystal structures, and urease inhibitory activity of cooper(II) complexes with schiff bases

Article abstract of DOI:10.1134/S1070328411020126

A new end-to-end thiocyanato-bridged polynuclear copper(II) complex, [Cu(CP)(μ_1,3-NCS)] _n ? nMeOH (I), and a new mononuclear copper(II) complex, [Cu(MP)(ONO₂)(OH₂)] (II) (CP = 4-chloro-2-[(pyridin-2-ylmethylimino)methyl]phenolate, MP = 5-methoxy-2-[(pyridin-2-ylmethylimino)methyl]phenolate), were prepared and structurally characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray diffraction. The crystal of I is orthorhombic: space group Pbca, a = 10.6161(16) A, b = 16.340(3) A, c = 18.840(3) A, V = 3268.0(9) A³, Z = 8. The crystal of II is triclinic: space group P 1, a = 7.5645(2), b = 8.9811(2), c = 11.9412(3) A, α = 74.4610(10)°, β = 80.5040(10)°, γ = 71.0940(10)°, V = 736.71(3) A³, Z = 2. The Cu atoms in the complexes are in square-pyramidal coordination. The biological test shows that both complexes have strong urease inhibitory activity.

Full text of DOI:10.1134/S1070328411020126

ISSN 1070ꢀ3284, Russian Journal of Coordination Chemistry, 2011, Vol. 37, No. 3, pp. 235–241. © Pleiades Publishing, Ltd., 2011.
Synthesis, Crystal Structures, and Urease Inhibitory Activity
of Cooper(II) Complexes with Schiff Bases1
C. Y. Wang* and J. Y. Ye
Department of Chemistry, Huzhou University, Huzhou 313000, P. R. China
* Eꢀmail: chenyi_wang@163.com
Received June 3, 2010
Abstract
MeOH (I), and a new mononuclear copper(II) complex, [Cu(MP)(ONO2)(OH2)] (II) (CP = 4ꢀchloroꢀ2ꢀ
[(pyridinꢀ2ꢀylmethylimino)methyl]phenolate, MP = 5ꢀmethoxyꢀ2ꢀ[(pyridinꢀ2ꢀylmethylimino)methyl]phenoꢀ
late), were prepared and structurally characterized by elemental analyses, infrared spectroscopy, and singleꢀcrystal
Xꢀray diffraction. The crystal of is orthorhombic: space group Pbca = 10.6161(16) = 16.340(3)
18.840(3) = 8. The crystal of II is triclinic: space group P1, = 7.5645(2), = 8.9811(2),
= 3268.0(9) Å3
= 11.9412(3) = 74.4610(10) = 80.5040(10) = 71.0940(10) = 2. The Cu
= 736.71(3) Å3
—A new endꢀtoꢀend thiocyanatoꢀbridged polynuclear copper(II) complex, [Cu(CP)(μ1,3ꢀNCS)]n ·
n
I
,
a
Å,
b
Å, c =
Å,
V
,
Z
a
b
c
Å
,
α
°
,
β
°
,
γ
°
,
V
, Z
atoms in the complexes are in squareꢀpyramidal coordination. The biological test shows that both complexes
have strong urease inhibitory activity.
DOI: 10.1134/S1070328411020126
INTRODUCTION
coma, and urinary catheter encrustation. High conꢀ
centration of ammonia arising from these reactions, as
well as accompanying pH elevation, has important
implications in medicine and agriculture [13, 14].
Therefore, urease inhibitors have recently attracted
much attention as potential new antiꢀulcer drugs. A
recent research indicated that the Schiff base comꢀ
plexes, especially for the copper(II) complexes, had
potent urease inhibitory activity [15, 16]. As a further
study of the urease inhibitors, in this paper, two new
copper(II) complexes, [Cu(CP)([Cu(CP)(µ1,3ꢀNCS)]n ·
During the last few years, there has been a great
effort to identify the biological role of copper, primaꢀ
rily through techniques associated with the interface
of biology, biochemistry, and coordination chemistry
[1–3]. It appears that the biological role of copper is
primarily in redox reactions and as a biological cataꢀ
lyst, although much remains to be understood [4, 5].
An extensive effort has been made to prepare and
characterize a variety of copper(II) complexes in an
attempt to model the physical and chemical behavior of
copperꢀcontaining enzymes [6]. The peculiarity of copꢀ
per lies in its ability to form complexes with coordination
numbers four, five, and six [7–9]. Urease is an important
class of enzyme involved in the degradative processing of
urea [10–12]. They are ubiquitous in nature and
directly associated with the formation of infection
stones and contribute to pathogenesis of pyelonephriꢀ
nMeOH (I) and [Cu(MP)(ONO2)(OH2)] (II), where
CP and MP are the new Schiff bases 4ꢀchloroꢀ2ꢀ
[(pyridinꢀ2ꢀylmethylimino)methyl]phenolate and 5ꢀ
methoxyꢀ2ꢀ[(pyridinꢀ2ꢀylmethylimino)methyl]phenolate,
respectively, were prepared and structurally characterꢀ
ized. The urease inhibitory activities of the complexes
tis, urolithiasis, ammonia encephalopathy, hepatic were determined.
Cl
N
N
N
N
O
OH
(MP)
OH
(CP)
EXPERIMENTAL
ucts (Lancaster) and used without further purification.
Jack bean urease was obtained from SigmaꢀAldrich
Co. (St. Louis, MO, USA). C, H, and N analyses were
performed with a PerkinElmer 2400 series II analyzer.
The infrared spectra (KBr pellet) were recorded using
a FTS165 BioꢀRad FTꢀIR spectrophotometer in the
Materials and Measurements
All chemicals and reagents used for the preparation
of the ligands and complexes were commercial prodꢀ
1
The article is published in the original.
235

236
WANG, YE
Table 1. Crystallographic parameters and summary of data collection and refinement for complexes I and II
Value
Parameter
I
II
M
399.3
384.8
Crystal shape/color
Crystal size, mm
Crystal system
Block/blue
Block/blue
0.32
×
0.32
×
0.30
0.23 × 0.20 × 0.20
Orthorhombic
Triclinic
Space group
Pbca
P1
a
, Å
, Å
10.6161(16)
16.340(3)
18.840(3)
90
7.5645(2)
8.9811(2)
b
c
, Å
, deg
, deg
, deg
11.9412(3)
74.4610(10)
80.5040(10)
71.0940(10)
736.71(3)
2
α
β
90
γ
90
V, Å3
3268.0(9)
8
Z
μMo, mm–1
1.639
1.521
T
T
0.622
0.721
min
max
0.639
0.756
Reflections/parameters
Independent reflections
Observed reflections
Restraints
19044/210
3560
4448/224
3104
2614
2556
0
3
F(000)
1624
394
Goodnessꢀofꢀfit on F2
1.009
1.022
R1
,
,
wR2
(
I
≥
2
σ
(
I
))*
0.0369, 0.0890
0.0585, 0.1021
0.0348, 0.0766
0.0471, 0.0830
R1
wR2 (all data)*
1/2
*R
=
∑||
F
|
–
|F
||
/
∑|
F
|,
wR = [
∑w
(F2o – F2c)2
/
∑w
(F2o)2 ]
.
1
o
c
o
2
range 4000–400 cm–1. Conductance measurements which was washed with methanol and dried in air. The
yield was 96%.
were performed using a DDSꢀ307 conductivity meter.
For C13H11N2OCl
anal. calcd., %: C, 63.3;
H, 4.5;
H, 4.6;
N, 11.4.
N, 11.3.
Synthesis of CP
Found, %:
C, 63.0;
A methanolic solution (10 ml) of 2ꢀaminomethꢀ
ylpyridine (1.0 mmol, 108.2 mg) was added with stirꢀ
ring to a methanolic solution (20 ml) of 5ꢀchlorosaliꢀ
cylaldehyde (1.0 mmol, 156.6 mg). The mixture was
stirred at reflux for 30 min to give a yellow solution.
Synthesis of MP
A methanolic solution (10 ml) of 2ꢀaminomethꢀ
The solution was evaporated to give a yellow powder, ylpyridine (1.0 mmol, 108.2 mg) was added with stirꢀ
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
No. 3
2011

SYNTHESIS, CRYSTAL STRUCTURES, AND UREASE INHIBITORY ACTIVITY
237
Table 2. Selected bond lengths and bond angles for the complexes*
Bond
d
, Å
Bond
d, Å
I
Cu(1)–O(1)
Cu(1)–N(2)
Cu(1)–S(1)i
1.919(2)
2.015(3)
2.7944(11)
Cu(1)–N(1)
Cu(1)–N(3)
1.947(2)
1.962(3)
II
Cu(1)–O(1)
Cu(1)–N(2)
Cu(1)–O(4)
1.8917(17)
1.982(2)
2.601(2)
Cu(1)–N(1)
Cu(1)–O(3)
1.926(2)
1.9851(18)
Angle
ω
, deg
Angle
ω, deg
I
O(1)Cu(1)N(1)
N(1)Cu(1)N(3)
N(1)Cu(1)N(2)
O(1)Cu(1)S(1)i
N(3)Cu(1)S(1)i
92.85(10)
161.96(11)
82.36(10)
91.51(7)
O(1)Cu(1)N(3)
O(1)Cu(1)N(2)
N(3)Cu(1)N(2)
N(1)Cu(1)S(1)i
N(2)Cu(1)S(1)i
90.41(10)
173.24(10)
92.71(11)
100.24(7)
94.04(8)
97.40(9)
II
O(1)Cu(1)N(1)
N(1)Cu(1)N(2)
N(1)Cu(1)O(3)
O(1)Cu(1)O(4)
N(2)Cu(1)O(4)
93.73(8)
83.17(9)
172.67(8)
102.48(8)
80.59(8)
O(1)Cu(1)N(2)
O(1)Cu(1)O(3)
N(2)Cu(1)O(3)
N(1)Cu(1)O(4)
O(3)Cu(1)O(4)
176.14(8)
88.38(7)
94.41(8)
104.68(8)
81.67(8)
i
* Symmetry code: –1/2 +
x, 3/2 –
y, 1 –
z.
Table 3. Geometric parameters of hydrogen bond for complexes I and II*
Distance,
Å
Contact D–H···A
Angle D–H···A, deg
168
D–H
0.82
H···A
D···A
I
O(2)–H(2)···O(1)
2.00
II
2.67(2)
2.806(4)
O(3)–(3
O(3)–(3
O(3)–(3
B
)···N(3)ii
)···O(5)ii
0.84(3)
0.84(3)
0.84(4)
3.431(3)
2.714(3)
2.692(3)
150(3)
174(4)
168(4)
B
1.873(11)
1.86(4)
A
)···O(1)ii
ii
* Symmetry code: 1 –
x, 1 –
y, 1 –
z.
ring to a methanolic solution (20 ml) of 4ꢀmethoxysalꢀ
icylaldehyde (1.0 mmol, 152.2 mg). The mixture was
stirred at reflux for 30 min to give a yellow solution.
The solution was evaporated to give a yellow powder,
which was washed with methanol and dried in air. The
yield was 92%.
Synthesis of
I
A methanolic solution (5 ml) of Cu(NO3)2
⋅
3H2O
(0.1 mmol, 24.2 mg) was added with stirring to a
methanolic solution (10 ml) of CP (0.1 mmol,
24.7 mg) and ammonium thiocyanate (0.1 mmol,
7.6 mg). The mixture was stirred for 30 min at room
temperature and filtered. Upon keeping the filtrate in
air for few days, blue blockꢀshaped crystals of I, suitꢀ
able for Xꢀray singleꢀcrystal diffraction, were formed
on the bottom of the vessel. The crystals were collected
For C14H14N2O2
anal. calcd., %: C, 69.4;
Found, %: C, 69.6;
H, 5.8;
H, 5.8;
N, 11.6.
N, 11.5.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
No. 3
2011

238
WANG, YE
Cl(1)
C(5)
C(4)
C(3)
C(6)
C(1)
C(2)
C(7)
C(8)
N(1)
C(15)
O(1)
O(2)
Cu(1)
N(3)
C(9)
N(2)
C(14)
C(13)
C(10)
C(11)
S(1)
C(12)
Fig. 1. Molecular structure of
I
at 30% ellipsoid. Hydrogen bonds are shown as dashed lines.
z
y
x
Fig. 2. Molecular packing diagram of
I. Hydrogen bonds are shown as dashed lines.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
No. 3
2011

SYNTHESIS, CRYSTAL STRUCTURES, AND UREASE INHIBITORY ACTIVITY
C(8)
239
C(6)
C(7)
C(10)
C(9)
C(11)
C(12)
C(5)
N(1)
C(1)
O(1)
N(2)
Cu(1)
O(3)
C(4)
O(2)
C(13)
C(2)
C(3)
O(4)
C(14)
N(3)
O(6)
O(5)
Fig. 3. Molecular structure of II at 30% ellipsoid. Hydrogen bonds are shown as dashed lines.
by filtration, washed three times with cold methanol,
and dried in air. The yield was 53% based on CP.
0
For C15H14N3O2SClCu
anal. calcd., %: C, 45.1;
Found, %: C, 45.4;
H, 3.5;
H, 3.7;
N, 10.5.
N, 10.3.
y
x
Synthesis of II
A methanolic solution (5 ml) of Cu(NO3)2
⋅
3H2O
(0.1 mmol, 24.2 mg) was added with stirring to a
methanolic solution (10 ml) of MP (0.1 mmol,
24.2 mg). The mixture was stirred for 30 min at room
temperature and filtered. Upon keeping the filtrate in
air for few days, blue blockꢀshaped crystals of II, suitꢀ
able for Xꢀray singleꢀcrystal diffraction, were formed
on the bottom of the vessel. The crystals were collected
by filtration, washed three times with cold methanol,
and dried in air. The yield was 72% based on MP.
For C14H15N3O6Cu
z
anal. calcd., %: C, 43.7;
Found, %: C, 43.4;
H, 3.9;
H, 4.1;
N, 10.9.
N, 11.0.
Xꢀray structure determination
A suitable single crystal of each complex was
mounted on a glass fiber. The diffraction experiments
were carried out on a Bruker AXS SMART CCD difꢀ
fractometer. The program SMART was used for colꢀ
lecting frames of data, indexing reflections, and deterꢀ
mination of lattice parameters [17]. SAINT was used
for integration of the intensity of reflections and scalꢀ
ing [17], SADABS was used for absorption correction
[18], and SHELXTL was applied for space group and
Fig. 4. Molecular packing diagram of II. Hydrogen bonds
are shown as dashed lines.
ference Fourier map and refined isotropically with O–H
, respecꢀ
tively. Other hydrogen atoms were placed in idealized posiꢀ
were located from a difꢀ tions and allowed to ride on the connecting atoms. The
structure determination and leastꢀsquares refinements and H···H distances restrained to 0.85 and 1.37
on
2 [19]. All nonꢀhydrogen atoms were refined anisoꢀ
tropically. The water H atoms in
Å
F
I
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
No. 3
2011

240
WANG, YE
crystallographic data for the complexes are summarized in
Table 1. Selected bond lengths and angles are listed in Taꢀ compound is an endꢀtoꢀend thiocyanatoꢀbridged
Figure 1 gives a perspective view of complex I. The
ble 2, hydrogen bonds are shown in Table 3.
polynuclear copper(II) complex. The asymmetric unit
of consists of a Cu(CP)(NCS) moiety and a methaꢀ
I
Atomic coordinates and other structural parameꢀ
ters of the complexes have been deposited with the Camꢀ
nol molecule of crystallization. The methanol moleꢀ
cule is linked to the complex molecules through the
O(2)–H(2)···O(1) hydrogen bond.
bridge Crystallographic Data Centre (nos. 775269 (I)
and 775270 (II); deposit@ccdc.cam.ac.uk or http://
www.ccdc.cam.ac.uk).
The Cu atom is fiveꢀcoordinated and best described
as having a square pyramidal coordination. The basal
plane of the square pyramidal coordination is defined
by the phenolate O, imine N, and pyridine N atoms of
a Schiff base ligand, and one N atom of a thiocyanate
bridge. The apical position of the square pyramid is occuꢀ
pied by one S atom of a thiocyanate bridge. The deviation
of the atom Cu(1) from the leastꢀsquares plane defined by
Measurement of urease
The assay mixture containing 25
μl of jack bean
urease and 25 l (100 g) of the test compound was
μ
μ
preincubated for 0.5 or 3 h at room temperature in a
96ꢀwell assay plate. After preincubation, 0.2 ml of a
100 mM phosphate buffer (pH 6.8) containing
500 mmol/l urea and 0.002% phenol red were added
and incubated at room temperature. The reaction time
was measured by a microplate reader (570 nm), which
was required for enough ammonium carbonate to form
to raise the pH of a phosphate buffer from 6.8 to 7.7.
the four basal donor atoms is 0.196(1)
Å. The bond
lengths subtended at the metal center are comparable
to the corresponding values observed in other similar
copper(II) complexes [21–23], and, as expected, the
bonds involving pyridine N atom is longer than that
involving imine N atom. The distortion of the square
pyramidal coordination is revealed by the bond angles
between the apical and basal donor atoms, which
range from 91.5(1)
bond angle in the complex deviates from 90
7.6(1) , as a result of the strain created by the fiveꢀ
°
to 100.2(1)
°
. The N(1)Cu(1)N(2)
RESULTS AND DISCUSSION
°
by
Two new Schiff bases were easily synthesized from
the reaction of 2ꢀaminomethylpyridine with 5ꢀchloroꢀ
salicylaldehyde and 4ꢀmethoxysaliꢀcylaldehyde,
respectively, in methanol. The analytical and spectral
data are completely consistent with the proposed forꢀ
°
membered chelate ring Cu(1)/N(1)/C(8)/C(9)/N(2).
The thiocyanate group is nearly linear and shows bent
coordination with the Cu atoms (N(3)–C(14)–
S(1)/Cu(1)–N(3)–(C(14)/Cu(1)i–S(1)–C(14) =
mulas of the compounds. Complex
by mixing equimolar quantities of CP, NH4NCS, and
Cu(NO3)2 3H2O in methanol, yielding a thiocyꢀ
I was synthesized
i
178.8(3)
1/2 +
°
x
/161.9(3)
°
/96.1(1)°, symmetry code for :
).
⎯
, 3/2 – , 1 – z
y
⋅
In the crystal structure of I, the mononuclear copꢀ
per(II) complex units are linked by the endꢀtoꢀend
thiocyanate bridges to form polymeric chains running
anatoꢀbridged polynuclear copper(II) complex. In the
preparation of complex II, CP and NH4NCS were
replaced by MP, yielding a mononuclear copper(II)
complex. Both complexes are stable in air at room
temperature. They are soluble in DMF, DMSO,
methanol, ethanol, and acetonitrile, and insoluble
along the
x axis, as shown in Fig. 2. The methanol
molecules are linked to the chains through O–H···O
hydrogen bonds.
in water. The molar conductivities of complexes
and II measured in acetonitrile with concentrations
of 10–3 mol/l are 17.6 and 117.3 Ω–1 cm2 mol–1
respectively, indicating that complex is a nonꢀ
electrolyte, while the nitrate of complex II is deloꢀ
calized in the test solution.
I
Figure 3 gives a perspective view of complex II. The
Cu atom in the complex is fiveꢀcoordinated and best
described as having a square pyramidal coordination.
The basal plane of the square pyramidal coordination
is defined by the phenolate O, imine N, and pyridine
N atoms of a Schiff base ligand, and one water O atom.
,
I
In the infrared spectra of the Schiff bases, the weak The apical position of the square pyramid is occupied
and broad absorption bands at 3350–3450 cm–1 are by one O atom of a nitrate anion. The deviation of the
assigned to the stretching vibration of the phenolic atom Cu(1) from the leastꢀsquares plane defined by
O⎯
H bonds. The strong absorption bands at 1637 cm–1 the four basal donor atoms is 0.643(1) Å. The basal
for CP and .1635 cm–1 for MP are assigned to the bond lengths subtended at the metal center are comꢀ
azomethine groups, (C=N) [20], which are shifted to parable to those in , and the corresponding values
lower frequencies in the complexes (1621 cm–1 for
observed in other similar copper(II) complexes [21–
ν
I
I
and 1618 cm–1 for II). The weak and broad absorption 25]. As expected, the bonds involving pyridine N atom
bands at 3350–3500 cm–1 in the complexes are is longer than that involving the imine N atom. It
assigned to the stretching vibration of the methanol is notable that the apical bond of the square pyramidal
and water O–H bonds. The strong absorption band of coordination is a little longer than usual (Cu(1)–O(4) =
the thiocyanate group in
absorption band of the nitrate group in II is at coordinated to the metal atom. The distortion of the
1383 cm–1.
square pyramidal coordination is revealed by the bond
I
is at 2109 cm–1. The strong 2.601(2) Å), indicating that the O(4) atom is weakly
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
No. 3
2011

SYNTHESIS, CRYSTAL STRUCTURES, AND UREASE INHIBITORY ACTIVITY
241
5. Musie, G.T., Li, X., and Powell, D.R., Inorg. Chim. Acꢀ
ta, 2003, vol. 348, p. 69.
6. Reddy, P.A.N., Datta, R., and Chakravarty, A.R., Inorg.
Chem. Commun., 2000, vol. 3, no. 6, p. 322.
angles between the apical and basal donor atoms,
which range from 81.7(1) to 104.7(1) The
N(1)Cu(1)N(2) bond angle in the complex deviates from
90 by 6.8(1) as a result of the strain created by the fiveꢀ
°
°.
°
°
7. Arnold, P.J., Davies, S.C., Durrant, M.C., et al., Inorg.
Chim. Acta, 2003, vol. 348, p. 143.
8. Raptopoulou, C.P., Papadopoulos, A.N., Malamatari, D.A.,
et al., Inorg. Chim. Acta, 1998, vol. 272, no. 1–2, p. 283.
9. Ray, M.S., Bhattacharya, R.B., Chaudhuri, S., et al.,
Polyhedron, 2003, vol. 22, no. 4, p. 617.
membered chelate ring Cu(1)N(1)C(8)C(9)N(2).
In the crystal structure of II, adjacent two monoꢀ
nuclear copper(II) complex molecules are linked by
the coordinate water molecules through four O–H···O
hydrogen bonds to form a dimer as shown in Fig. 4.
In both complexes, the square pyramidal coordinaꢀ
10. Amtul, Z., AttaꢀurꢀRahman, Siddiqui, R.A., et al.,
Curr. Med. Chem., 2002, vol. 9, no. 14, p. 1323.
tion can be proved by the structural index
which represents the relative amount of trigonality
(square pyramid, = 0; trigonal bipyramid, = 1).
The values for complexes and II are 0.19 and 0.06,
τ value [26],
11. Mobley, H.L.T. and Hausinger, R.P., Microbiol. Rev.
1989, vol. 53, no. 1, p. 85.
12. Mobley, H.L.T., Island, M.D., and Hausinger, R.P.,
,
τ
τ
τ
I
indicating that the coordination is best described as
Microbiol. Rev., 1995, vol. 59, no. 3, p. 451.
13. Todd, M.J. and Hausinger, R.P., Biochemistry, 2000,
vol. 39, no. 18, p. 5389.
14. Pearson, M.A., Michel, L.O., Hausinger, R.P., et al.,
Biochemistry, 1997, vol. 36, no. 26, p. 8164.
trigonal bipyramid.
The biological test indicates that both complexes
have satisfactory urease inhibitory activity with the
IC50 values of 31.3 0.2
for II, which are superior to that of the acetohydroxꢀ
amic acid (37.23 0.27 ) coassayed as a standard
μM for I and 20.5 0.3 μM
15. Wang, C.ꢀY., Ye, J.ꢀY., Lv, C.ꢀY., et al., J. Coord. Chem.
2009, vol. 62, no. 13, p. 2164.
16. Wang, C.ꢀY., J. Coord. Chem., 2009, vol. 62, no. 17,
p. 2860.
17. SMART & SAINT Software Reference Manuals
sion 6.22, Madison (WI, USA): Bruker AXS Analytic
XꢀRay Systems Inc., 2000.
18. Sheldrick, G.M., SADABS
sorption Correction Göttingen (Germany): Univ. of
Göttingen, 2000.
19. Sheldrick, G.M., SHELXTL Reference Manual
,
μM
reference against the urease. When compared with
those we reported previously, it can be seen that the
activity of the two complexes in this paper is comparaꢀ
ble to those of the copper(II) complexes [15, 16] and
superior to those of the zinc(II) complexes [27]. Furꢀ
ther work needs to be done to explore highly efficient
urease inhibitors.
,
Verꢀ
,
Software for Empirical Abꢀ
,
ACKNOWLEDGMENTS
,
Verꢀ
sion 5.1, Madison (WI, USA): Bruker AXS, Analytic
XꢀRay systems Inc., 1997.
20. Wang, C.ꢀY., Pol. J. Chem., 2008, vol. 82, no. 7, p. 1353.
This work was financially supported by the Natural
Science Foundation of China (no. 31071856), the
Applied Research Project on Nonprofit Technology of
Zhejiang Province (no. 2010C32060), and the Natural
Science Foundation of Zhejiang Province
(no. Y407318).
21. Wang, C.ꢀY., Li, J.ꢀF., and Cao, F., Acta Crystallogr.
2010, vol. 66, no. 4, p. m445.
22. Roper, J.R., Paulus, H., and Elias, H., Inorg. Chem.
1989, vol. 28, no. 12, p. 2323.
,
E
,
,
23. Choudhury, C.R., Dey, S.K., Karmakar, R., et al., New
J. Chem., 2003, vol. 27, no. 9, p. 1360.
REFERENCES
24. Fontecha, J.B., Goetz, S., and McKee, V., Angew.
Chem. Int. Ed., 2002, vol. 41, no. 23, p. 4553.
1. Collinson, S.R. and Fenton, D.E., Coord. Chem. Rev.
1996, vol. 148, p. 19.
2. Hossain, M.E., Alam, M.N., Begum, J., et al., Inorg.
Chim. Acta, 1996, vol. 249, no. 2, p. 207.
3. Tarafder, M.T.H., Jin, K.T., Crouse, K.A., et al., Polyꢀ 26. Addison, A.W., Rao, T.N., Reedijk, J., et al., Dalton
hedron, 2002, vol. 21, no. 25–26, p. 2547.
Trans., 1984, no. 7, p. 1349.
4. GarcíaꢀRaso, Á., Fiol, J.J., L pezꢀZafra, A., et al., 27. Wang, C.Y., Russ. J. Coord. Chem., 2010, vol. 36, no. 3,
Polyhedron, 2003, vol. 22, no. 3, p. 403. p. 177.
,
25. Latour, J.ꢀM., Tandon, S.S., and Povey, D.C., Acta
Crystallogr., C, 1989, vol. 45, no. 1, p. 7.
ó
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
No. 3
2011