Synthesis, crystal structures, and urease inhibition studies of two new Schiff-base copper complexes derived from n-butylamine

Article abstract of DOI:10.1080/00958972.2011.637169

Two Schiff-base copper(II) complexes, bis(N-n-butyl-5- chlorosalicylaldiminato) copper(II) (1) and bis(N-n-butyl-4- methoxysalicylaldiminato) copper(II) (2), were synthesized and their solid-state structures were determined by X-ray crystallography. Compl

Full text of DOI:10.1080/00958972.2011.637169

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Synthesis, crystal structures, and
urease inhibition studies of two new
Schiff-base copper complexes derived
from n-butylamine
Yuguang Li a b , Zuowen Li a b , Yang Liu a b , Xiongwei Dong a b
Yongming Cui a b
&
a School of Chemistry and Chemical Engineering, Engineering
Research Center for Clean Production of Textile Printing, Ministry
of Education, Wuhan Textile University, Wuhan 430073, People's
Republic of China
b School of Chemistry and Chemical Engineering, State Key
Laboratory of Coordination Chemistry, Nanjing University, Nanjing
210093, People's Republic of China
Published online: 07 Dec 2011.
To cite this article: Yuguang Li , Zuowen Li , Yang Liu , Xiongwei Dong & Yongming Cui (2012)
Synthesis, crystal structures, and urease inhibition studies of two new Schiff-base copper
complexes derived from n-butylamine, Journal of Coordination Chemistry, 65:1, 19-27, DOI:
10.1080/00958972.2011.637169
To link to this article: http://dx.doi.org/10.1080/00958972.2011.637169
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Journal of Coordination Chemistry
Vol. 65, No. 1, 10 January 2012, 19–27
Synthesis, crystal structures, and urease inhibition
studies of two new Schiff-base copper
complexes derived from n-butylamine
YUGUANG LI*yz, ZUOWEN LIyz, YANG LIUyz,
XIONGWEI DONGyz and YONGMING CUI*yz
ySchool of Chemistry and Chemical Engineering, Engineering Research Center for
Clean Production of Textile Printing, Ministry of Education, Wuhan Textile University,
Wuhan 430073, People’s Republic of China
zSchool of Chemistry and Chemical Engineering, State Key Laboratory of Coordination
Chemistry, Nanjing University, Nanjing 210093, People’s Republic of China
(Received 4 September 2011; in final form 17 October 2011)
Two Schiff-base copper(II) complexes, bis(N-n-butyl-5-chlorosalicylaldiminato) copper(II) (1)
and bis(N-n-butyl-4-methoxysalicylaldiminato) copper(II) (2), were synthesized and their solid-
state structures were determined by X-ray crystallography. Complex 1 displays a distorted
square-planar geometry, while 2 possesses square-planar geometry. Copper(II) complexes 1 and
2 showed strong inhibitory activity against jack bean urease (IC50 ¼ 2.7, 3.5 mmol Lꢀ1),
compared with acetohydroxamic acid (IC50 ¼ 63.00 mmol Lꢀ1). A molecular modeling study
was carried out via the DOCK program to gain understanding of the potent inhibitory activity
of these copper species against jack bean urease.
Keywords: Schiff-base copper(II) complexes; Crystal structures; 5-Chlorosalicylaldehyde;
4-Methoxysalicylaldehyde; Urease inhibitors
1. Introduction
Transition metal complexes of Schiff bases derived from salicylaldehyde and its
derivatives have potential applications [1–9], acting as single-molecule magnets (SMMs)
[2], as luminescent probes [3], as catalysts for specific DNA [4, 5], and RNA [6] cleavage
reactions. Salen-type Schiff bases may be bidentate N,O- [7] or tridentate N,O,O-
donors [8] to yield a variety of complexes with other ligands, such as azide, thiocyanate,
and carboxylate. Schiff-base copper(II) complexes attract considerable interest because
they display a range of stereochemistries from square planar to pseudo-tetrahedral in
the solid state [10–13]. It has been proposed that the extent of distortion from square-
planar geometry in those molecules results from the size of the substituent at the
coordinating nitrogen [11], electronic effects [12], and crystal-packing forces [13, 14].
For example, pseudo-tetrahedral distortion in the solid-state structures of some
*Corresponding authors. Email: liyg2010@wtu.edu.cn; cym981248@163.com
Journal of Coordination Chemistry
ISSN 0095-8972 print/ISSN 1029-0389 online ß 2012 Taylor & Francis
http://dx.doi.org/10.1080/00958972.2011.637169

20
Y. Li et al.
copper(II) complexes with tetradentate thiolate Schiff bases (N2S2) depends on the
backbone flexibility and as the backbone becomes more flexible, distortion grows [15].
Urease (urea amidohydrolase; E.C.3.5.1.5) catalyzes the rapid hydrolysis of urea in
algae, bacteria, fungi, and plants, which causes negative side effects in health such as
kidney stones, pyelonephritis, peptic ulcers [16], and in agriculture such as the efficiency
of soil nitrogen fertilization, root damage and ammonia volatilization [17]. It is
important to find excellent urease inhibitors [18]. Some transition metal complexes
(M ¼ Cu, Co, Ni, etc.) with potent inhibitory activities against urease have been
reported by our group [19]. Mononuclear copper(II) complexes show better inhibitory
activities. In this article, we report two new Schiff-base copper(II) complexes, bis(N-n-
butyl-5-chlorosalicylaldiminato) copper(II) (1) and bis(N-n-butyl-4-methoxysalicylaldi-
minato) copper(II) (2). A preliminary docking study using the DOCK program was
performed to model the inhibitory activity of these Schiff-base copper complexes
against jack bean urease.
2. Results and discussion
2.1. Synthesis
The Schiff bases in this article were prepared by the reaction of n-butylamine with
5-chlorosalicylaldehyde and 4-methoxysalicylaldehyde in 75–89% yield in methanol.
These ligands are yellow crystallite, stable compounds in air at room temperature,
soluble in common polar organic solvents, such as MeCN, MeOH, and EtOH.
Complexes 1 and 2 were obtained from the reaction of the Schiff bases with
Cu(NO3)2 ꢁ 3H2O in methanol. The elemental analyses are in agreement with the
chemical formulae for 1 and 2.
2.2. Crystal structure description
The Schiff bases of 1 and 2 were obtained from condensation of n-butylamine with
5-chlorosalicylaldehyde and 4-methoxysalicylaldehyde, respectively. Single-crystal
X-ray diffraction reveals that bis(N-n-butyl-5-chlorosalicylaldiminato) copper(II) (1)
crystallizes in the triclinic space group P-1. The solid-state structure of 1 is shown in
figure 1. The [CuO2N2] unit of 1 is slightly distorted from square planar toward
tetrahedral geometry. The dihedral angle between two planes O1–Cu1–N1 and O2–
Cu1–N2 of 1 is 10.0(2)ꢂ. Dihedral angles of 0ꢂ and 90ꢂ would be expected for planar and
tetrahedral geometries, respectively [20, 21]. The deviation may result from weak
˚
Cu1 ꢁ ꢁ ꢁ O2# interactions [2.693(4) A] between adjacent molecules (symmetry code:
# 1 ꢀ x, 1 ꢀ y, 2 ꢀ z), constructing a dinuclear copper unit. These units further form a
˚
3-D network via intermolecular Cl2 ꢁ ꢁ ꢁ Cu1# interactions [3.573(7) A] as shown in figure
2 (symmetry code: # 1 ꢀ x, ꢀy, 2 ꢀ z). Analogous square-planar copper(II) species were
previously reported [22].
In contrast to 1, bis(N-n-butyl-5-methoxysalicylaldiminato) copper(II) (2) crystallizes
in the monoclinic system, with space group P21/c. The crystal structure of 2 is shown in
figure 3. In 2, the copper(II) is four-coordinate by two imino nitrogen atoms and two
phenolic oxygen atoms from two bidentate Schiff-base ligands in the usual trans

Schiff-base copper complexes
21
Figure 1. An ORTEP diagram showing molecular structure of 1. Thermal ellipsoids are shown at 30%
probability level.
Figure 2. Molecular packing of 1 viewed along the c-axis of the unit cell.
Figure 3. An ORTEP diagram showing molecular structure of 2 (symmetry code: A 1 ꢀ x, ꢀy, ꢀz). Thermal
ellipsoids are shown at 30% probability level.
arrangement. The copper(II) of 2 lies on a center-of-inversion to offer a square-planar
geometry (symmetry code: 1 ꢀ x, ꢀy, ꢀz) and axial positions are vacant. Analogous
square-planar copper(II) species were previously reported [23, 24]. Adjacent molecules

22
Y. Li et al.
Figure 4. Molecular packing of 2 viewed along the b-axis of the unit cell.
Table 1. Crystal data for 1 and 2.
Compound
1
2
Empirical formula
Molecular weight
Temperature (K)
Crystal system
Space group
C22H26Cl2CuN2O2
484.89
291(2)
Triclinic
P-1
C24H32CuN2O4
476.06
291(2)
Monoclinic
P21/c
ꢂ
˚
Unit cell dimensions (A,
)
a
b
c
ꢀ
ꢁ
ꢂ
10.0896(13)
10.1001(14)
11.5270(15)
96.858(2)
91.112(2)
105.658(2)
1121.3(3), 2
1.436
502
1.232
4347/0/264
1.006
0.0487, 0.1064
13.251(3)
4.8850(13)
17.858(5)
90.00
93.558(4)
90.00
1153.7(5), 2
1.370
502
3
˚
Volume (A ), Z
Calculated density (g cmꢀ3
F(000)
)
ꢃ(Mo-Ka) (mmꢀ1
Data/restraint/parameters
)
0.979
2856/0/144
1.004
0.0533, 0.1385
Goodness-of-fit on F2
Final R1, wR2 [I 4 2ꢄ(I )]
˚
of 2 were connected through intermolecular C8–H8A ꢁ ꢁ ꢁ Cu1# [3.046(2) A] and
˚
C8–H8B ꢁ ꢁ ꢁ Cu1# bonds [3.040(2) A] as shown in figure 4 (symmetry code: # x, 1 þ y, z).
Table 1 summarizes the unit-cell parameters and details of data collection for the
crystallographic studies of 1 and 2. Selected bond lengths and angles from 1 are
presented in comparison with those for 2 in table 2. The differences in bond length of
E–Cu (E ¼ O, N) and the angles subtended at copper(II) in 1 and 2 are small, suggesting
that steric and electronic effects between the 5-chloro group and 4-methoxy group
are slightly different. These results indicate that crystal-packing forces play a key role
in determining conformational detail of such copper(II) species [25].
2.3. Inhibitory activity against Jack bean urease
Two Schiff bases derived from 5-chlorosalicylaldehyde and 4-methoxysalicylaldehyde
and the corresponding copper(II) complexes 1 and 2 were screened for inhibitory

Schiff-base copper complexes
23
ꢂ
˚
Table 2. Selected bond lengths (A) and angles ( ) for 1 and 2.
1
Cu1–O1
Cu1–O2
Cu1–N1
Cu1–N2
N1–C7
1.892(3)
1.910(2)
2.005(3)
2.016(3)
1.286(4)
1.285(4)
O1–Cu1–N1
O1–Cu1–N2
O1–Cu1–O2
O2–Cu1–N1
O2–Cu1–N2
N1–Cu1–N2
91.55(11)
87.77(11)
175.77(11)
90.26(10)
91.05(10)
170.66(10)
N2–C18
2
Cu1–O1
Cu1–O1#a
Cu1–N1
Cu1–N1#a
N1–C7
1.8793(16)
1.8793(16)
2.0063(19)
2.0063(19)
1.290(3)
O1–Cu1–N1
91.75(8)
91.75(8)
180.00(16)
88.25(8)
88.25(8)
O1#a–Cu1–N1#a
O1#a–Cu1–O1
O1–Cu1–N1#a
O1#a–Cu1–N1
N1–Cu1–N1
N1#a–C7#a
1.290(3)
180.00(11)
Symmetry code: #a: 1 ꢀ x, ꢀy, ꢀz.
activity against jack bean urease. The Schiff bases exhibit no ability to inhibit the urease
(IC50 ¼ 100 mmol Lꢀ1). Compared with the standard inhibitor acetohydroxamic acid
(AHA, IC50 ¼ 63.00 mmol Lꢀ1), 1 and 2 display potent inhibitory activity against jack
bean urease (IC50 ¼ 2.7 and 3.5 mmol Lꢀ1). Generally, heavy metal ions are believed to
inhibit urease by binding to the sulfhydryl groups of cysteines, and possibly nitrogen-
(histidine) and oxygen- (aspartic and glutamic acids) in the urease active site [26]. Thus
it can be seen that coordination to copper(II) ion improved inhibitory activity [27].
Complex 1 derived from 5-chlorosalicylaldehyde is slightly more potent than 2. This
defines the minimal substitution patterns in the aromatic ring for obtaining inhibitory
activity against jack bean urease.
2.4. Molecular docking study
As shown in figure 5(a) and (b), the binding models of 1 and 2 with jack bean urease
were simulated using the Dock program to validate their structure–activity relation-
ships [28–31]. The complex molecules were well-filled in the active pocket of the urease.
Additional interactions have been established in a variety of conformations because of
the flexibilities of the chelating phenolic oxygen atom and the amino acid residues of the
urease. The small cluster (20 occurrences) was ranked by energy level in the best
position of the complex-urease modeled molecules where the binding energy of the
amino acid residues and 1 and 2 are ꢀ5.15 kcalmolꢀ1 and ꢀ4.97 kcalmolꢀ1, respectively.
The phenol of 1 forms weak O ꢁ ꢁ ꢁ O interactions with the carboxylate of Asp494
˚
(Asp494 O ꢁ ꢁ ꢁ O1complex-1 ¼2.997(2) A) in the complex-urease modeled 1 (figure 5a). In
contrast, weak O ꢁ ꢁ ꢁ O interactions exist between the methoxyl of 2 and the carboxylate
˚
of Asp494 (Asp494 O ꢁ ꢁ ꢁ O2#complex-2 ¼ 2.856(2) A) (symmetry code: # 1 ꢀ x, ꢀy, ꢀz).
One hydrogen-bonding interaction forms between NH of MET637 and OMe of the
complex (figure 5b). The hydrogen-bonding distance and angle of MET637 N–
ꢂ
˚
H ꢁ ꢁ ꢁ O2complex-2 are 3.063(2) A and 161.9(2) , respectively. The results of molecular
docking provide an understanding of the present inhibitory activity of the two Schiff-
base copper complexes against jack bean urease.

24
Y. Li et al.
Figure 5. Molecular-binding model of 1 (a) and 2 (b) with the active site of jack bean urease. Hydrogen
bonds are presented as green dotted lines. Available in color online.
3. Experimental
3.1. Materials and measurements
Urease (from jack beans, type III, activity 22 units/mg solid), HEPES (Ultra) buffer,
and urea (Molecular Biology Reagent) were from Sigma. 5-Chlorosalicylaldehyde and
4-methoxysalicylaldehyde were purchased from Aldrich and used without puriEcation.
Elemental analyses for C, H, and N were carried out on a Perkin-Elmer 2400 analyzer.
IR spectra of solid samples were recorded using KBr pellets on a Nexus 870 FT-IR
spectrophotometer between 4000 and 400 cmꢀ1
.
3.2. Complexes synthesis
3.2.1. Synthesis of bis(N-n-butyl-5-chlorosalicylaldiminato) copper(II) (1). 5-Chloro-
salicylaldehyde (313 mg, 2 mmol) and n-butylamine (146 mg, 2 mmol) were dissolved
in methanol (25 mL). The mixture was stirred for 30 min to give an orange solution,
which was added to a methanol solution (10 mL) of Cu(NO3)2 ꢁ 3H2O (241 mg, 1 mmol).
The mixture was stirred for another 15 min at room temperature to give a yellow-green
solution and then Eltered. The Eltrate was kept in air for 7 days, black block crystals
were formed. The crystals were isolated, washed three times with distilled water, and
dried in a vacuum desiccator containing anhydrous CaCl2. Yield: 75%. Anal. Calcd for
C22H26Cl2CuN2O2: C, 54.49; H, 5.40; N, 5.78. Found (%): C, 54.40; H, 5.52; N, 5.71.
IR data (KBr, cmꢀ1): 3447, 2960, 2920, 2855, 1626, 1532, 1465, 1387, 1314, 1180, 1109,
818, 720, 658, 466, 427.
3.2.2. Synthesis of bis(N-n-butyl-4-methoxysalicylaldiminato) copper(II) (2). 4-Meth-
oxysalicylaldehyde (304 mg, 2 mmol) and n-butylamine (146 mg, 2 mmol) were dissolved
in methanol (25 mL). The mixture was stirred for 30 min to give an orange solution,
which was added to a methanol solution (2 mL) of Cu(NO3)2 ꢁ 3H2O (241 mg, 1 mmol).

Schiff-base copper complexes
25
The mixture was stirred for another 15 min at room temperature to give a yellow-green
solution and then Eltered. The Eltrate was kept in air for 7 days, black block crystals
were formed. The crystals were isolated, washed three times with distilled water, and
dried in a vacuum desiccator containing anhydrous CaCl2. Yield: 77%. Anal. Calcd
for C24H32CuN2O4: C, 60.55; H, 6.77; N, 5.88. Found (%): C, 60.39; H, 6.88; N, 5.89.
IR data (KBr, cmꢀ1): 3464, 2958, 2933, 2856, 1625, 1537, 1450, 1402, 1026, 833, 788,
507, 455.
3.3. Crystal structure determinations
X-ray crystallographic data [32] were collected on a Bruker SMART Apex II CCD
˚
diffractometer using graphite-monochromated Mo-Ka (l ¼ 0.71073 A) radiation. The
collected data were reduced using SAINT and empirical absorption corrections were
performed using SADABS. The structures were solved by direct methods and refined
against F2 by full-matrix least squares using SHELXTL version 5.1. All of the non-
hydrogen atoms were refined anisotropically. All hydrogen atoms were placed
geometrically in ideal positions and constrained to ride on their parent atoms. The
crystallographic data for 1 and 2 are summarized in table 1. Selected bond lengths and
angles are given in table 2.
3.4. Measurement of jack bean urease inhibitory activity
The measurement of urease was carried out according to the procedure reported by
Tanaka [33]. Generally, the assay mixture, containing 25 mL of jack bean urease
(12 kU Lꢀ1) and 25 mL of the tested complexes of different concentrations (dissolved in
DMSO : H2O ¼ 1 : 1 (v/v)), was preincubated for 1 h at 37ꢂC in a 96-well assay plate.
After preincubation, 200 mL of 100 mmolLꢀ1 HEPES (N-[2-hydroxy-ethyl] piperazine-
N0-[2-ethanesulfonic acid]) buffer [34] pH ¼ 6.8 containing 500 mmolLꢀ1 urea and
0.002% phenol red were added and incubated at 37ꢂC. The reaction time was measured
by microplate reader (570 nm), which was required to produce enough ammonium
carbonate to raise the pH of HEPES buffer from 6.8 to 7.7, the end-point being
determined by the color of phenol red indicator [35].
3.5. Docking simulations
Molecular docking of the inhibitor with the three-dimensional structure of jack bean
urease (entry 3LA4 in the Protein Data Bank) was carried out using the DOCK 4.2
program suite [28–31]. The graphical user interface AutoDockTools (ADT 1.4.5) was
performed to setup every inhibitor–enzyme interaction, where all hydrogen atoms were
added, Gasteiger charges were calculated and non-polar hydrogen atoms were merged
˚
to carbon atoms. The Ni initial parameters are set as r ¼ 1.170 A, q ¼ þ2.0, and van der
Waals well depth of 0.100 kcal molꢀ1. As performed by the graphical user interface
AutoDockTools, the catalytic center and the peripheral anionic site of the target protein
were scanned to evaluate the modeled binding mode of the inhibitor–urease complex.
The flexible docking of the ligand structures was done by the Lamarckian genetic

26
Y. Li et al.
algorithm (LGA), searching for favorable bonding conformations of the ligands at the
sites of the target protein.
4. Conclusion
This report describes the synthesis, crystal structures, and urease inhibitory activity of
two Schiff-base copper complexes, bis(N-n-butyl-5-chlorosalicylaldiminato) copper(II)
(1) and bis(N-n-butyl-4-methoxysalicylaldiminato) copper(II) (2). The geometry and
extent of distortion in the solid state of these complexes have been interpreted from
steric considerations and complemented with the help of electronic effects. On the basis
of the experimentally tested activity of 1 and 2 against jack bean urease, the preliminary
results of a molecular docking study provide hints on the structure–activity relationship
of such Schiff-base copper species.
Supplementary material
CCDC Nos 761919 and 761920 contain the supplementary crystallographic data for
1 and 2. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/
conts/retrieving.html, or from the Cambridge Crystallographic Data Centre, 12 Union
Road, Cambridge CB2 1EZ, UK; Fax: (þ44) 1223-336-033; or E-mail: deposit@ccdc.
cam.ac.uk.
Acknowledgments
This work was financially supported by China Postdoctoral Science Foundation
(20100481108), Natural Science Foundation of Hubei Province (2009CDA022), and the
Education Office of Hubei Province (D20091704, Q20101610).
References
[1] (a) S. Koner, S. Saha, T. Mallah, K.I. Okamoto. Inorg. Chem., 43, 840 (2004); (b) A.K. Sah, T. Tanase, M.
Mikuriya. Inorg. Chem., 45, 2083 (2006); (c) A. Martinez, C. Hemmert, C. Loup, G. Barre, B. Meunier. J.
Org. Chem., 71, 1449 (2006).
[2] (a) W. Wernsdorfer, R. Sessoli. Science, 284, 133 (1999); (b) M.N. Leuenberger, D. Loss. Nature, 410, 789
(2001).
[3] (a) D. Imbert, S. Comby, A.-S. Chauvin, J.-C. Bunzli. Chem. Commun., 1432 (2005); (b) V.W.W. Yam,
K.K.-W. Lo. Coord. Chem. Rev., 184, 157 (1999).
¨
[4] P.A.N. Reddy, M. Nethaji, A.R. Chakravarty. Eur. J. Inorg. Chem., 1440 (2004).
[5] A. Mukherjee, S. Dhar, M. Nethaji, A.R. Chakravarty. Dalton Trans., 349 (2005).
[6] R. Haner, J. Hall. Antisense Nucleic Acid Drug Dev., 7, 423 (1997).
¨
[7] I. Castillo, J.M. Ferna
[8] A. Erxleben, D. Schumacher. Eur. J. Inorg. Chem., 3039 (2001).
ndez-Gonzalez, J.L. Garate-Morales. J. Mol. Struct., 657, 25 (2003).
´ ´ ´

Schiff-base copper complexes
27
[9] (a) M.R. Bermejo, A.M. Gonzalez-Noya, V. Abad, M.I. Fernandez, M. Maneiro, R. Pedrido,
M. Vazquez. Eur. J. Inorg. Chem., 3696 (2004); (b) S. Banerjee, M.G.B. Drew, C.-Z. Lu, J. Tercero,
C. Diaz, A. Ghosh. Eur. J. Inorg. Chem., 2376 (2005).
[10] A.D. Garnovskii, A.L. Nivorozhin, V.I. Minkin. Coord. Chem. Rev., 126, 1 (1993).
[11] R.H. Holm, M.J. O’Connor. Prog. Inorg. Chem., 14, 241 (1971).
[12] H.S. Maslen, T.N. Waters. Coord. Chem. Rev., 17, 137 (1975).
[13] G.V. Panova, N.K. Vikulova, V.M. Potapov. Russ. Chem. Rev., 49, 655 (1980).
[14] (a) J.M. Ferna
Ruvalcaba, M. Aguilar-Martı
47, 3037 (1974).
´
ndez-G, F.A. Lo
pez-Duran, S. Hernandez-Ortega, V. Gomez-Vidales, N. Macıas-
´ ´ ´ ´ ´
´
nez. J. Mol. Struct., 612, 69 (2002); (b) H. Yokoi. Bull. Chem. Soc., Japan,
[15] (a) S. Knoblauch, R. Benedix, M. Ecke, T. Gelbrich, J. Sieler, F. Somoza, H. Hennig. Eur. J. Inorg.
Chem., 1393 (1999); (b) N. Goswami, D.M. Eichhorn. Inorg. Chim. Acta, 303, 271 (2000).
[16] H.L.T. Mobley, M.D. Island, R.P. Hausinger. Microbiol. Rev., 59, 451 (1995).
[17] Q. Zheng, O. van Cleemput, P. Demeyer, L. Baert. Biol. Fertil. Soils, 11, 41 (1991).
[18] (a) J.B. Sumner. J. Biol. Chem., 69, 435 (1926); (b) N.E. Dixon, C. Gazzola, R.L. Blakeley, B. Zerner.
J. Am. Chem. Soc., 97, 4131 (1975).
[19] (a) Y.-G. Li, D.-H. Shi, H.-L. Zhu, H. Yan, S.W. Ng. Inorg. Chim. Acta, 360, 2881 (2007); (b) D.-H. Shi,
Z.-L. You, C. Xu, Q. Zhang, H.-L. Zhu. Inorg. Chem. Commun., 10, 404 (2007); (c) Y.-M. Cui,
W.-X. Yan, Y.-J. Cai, W. Chen, H.-L. Zhu. J. Coord. Chem., 63, 3706 (2010); (d) Y.-M. Cui, Y. Li,
Y.-J. Cai, W. Chen, H.-L. Zhu. J. Coord. Chem., 64, 610 (2011).
[20] P.E. Kruger, N. Martin, M. Nieuwenhuyzen. J. Chem. Soc., Dalton Trans., 1966 (2001).
[21] (a) F.-Z. Liang, J.-P. Ma, J.-H. Zhu. Chin. J. Inorg. Chem., 22, 115 (2006); (b) J. Costamagna, F. Caruso,
J. Vargas, V. Manriquez. Inorg. Chim. Acta, 267, 151 (1998).
[22] (a) J.M. Fernandez-G, M. del. R. Patino-Maya, R.A. Toscano, L. Velasco, M. Otero-Lopez,
M. Aguilar-Martinez. Polyhedron, 16, 4371 (1997); (b) R. Kilincarslan, H. Karabiyik, M. Ulusoy,
M. Aygun, B. Cetinkaya, O. Buyukgungor. J. Coord. Chem., 59, 1649 (2006).
[23] (a) S. Dhar, D. Senapati, P.K. Das, P. Chattopadhyay, M. Nethaji, A.R. Chakravarty. J. Am. Chem.
Soc., 125, 12118 (2003); (b) P.C. Jain, J.M. Bindlish, R.P. Kashyap. J. Chem. Soc., Dalton Trans.,
2129 (1976).
[24] (a) S.J. Cline, J.R. Wasson, W.E. Hatfield, D.J. Hodgson. J. Chem. Soc., Dalton Trans., 1051 (1978);
(b) P. Gili, P.M. Zarza, P. Nunez, A. Medina, M.C. Diaz, M.G. Martin, J.M. Arrieta, M. Vlassi,
G. Germain, M. Vermeire, L. Dupont. J. Coord. Chem., 20, 273 (1989).
[25] W. Chen, P. Miao, Y.G. Li, H.L. Zhu, Q.F. Zeng. Russ. J. Coord. Chem., 36, 929 (2010).
[26] (a) B. Krajewska. J. Enzyme Inhib. Med. Chem., 23, 535 (2008); (b) B. Krajewska, W. Zaborska,
M. Chudy. J. Inorg. Biochem., 98, 1160 (2004); (c) W. Zaborska, B. Krajewska, M. Leszko, Z. Olech.
J. Mol. Catal. B: Enzym., 13, 103 (2001); (d) C. Follmer, C.R. Carlini. Arch. Biochem. Biophys.,
435, 15 (2005).
[27] (a) W.H.R. Shaw, D.N. Raval. J. Am. Chem. Soc., 83, 3184 (1961); (b) X. Dong, Y. Li, Z. Li, D. Gong,
H.-L. Zhu. Transition Met. Chem., 36, 319 (2011); (c) B. Krajewska. J. Chem. Technol. Biotechnol.,
52, 157 (1991).
[28] R. Huey, G.M. Morris, A.J. Olson, D.S. Goodsell. J. Comput. Chem., 28, 1145 (2007).
[29] A. Balasubramanian, K. Ponnuraj. J. Mol. Biol., 400, 274 (2010).
[30] G. Estiu, D. Suarez, K.M. Merz. J. Comput. Chem., 27, 1240 (2006).
´
[31] K. Takishima, T. Suga, G. Mamiya. Eur. J. Biochem., 175, 151 (1988).
[32] (a) Bruker, SMART (Version 5.63), SAINT (Version 6.02), SADABS (Version 2.03). Bruker AXS Inc.,
Madison, WI (2000); (b) G.M. Sheldrick, Acta Crystallogr., A64, 112 (2008).
[33] T. Tanaka, M. Kawase, S. Tani. Life Sci., 73, 2985 (2003).
[34] W. Zaborska, B. Krajewska, Z. Olech. J. Enzyme Inhib. Med. Chem., 19, 65 (2004).
[35] D.D. van Slyke, R.M. Archibald. J. Biol. Chem., 154, 623 (1944).