Preparation and spectral and biological investigation of vic-dioxime ligands containing piperazine moiety and their mononuclear transition-metal complexes

Article abstract of DOI:10.1080/00397911.2013.777743

Two vic-dioxime ligands, N-(4-benzylpiperazine-1-yl) p-tolylglyoxime (L¹H₂) and N,N′-bis(4-benzylpiperazine-1-yl) glyoxime (L²H₂) containing piperazine moieties were synthesized, and their Ni(II) Cu(II) Co(II) and Zn(II) complexes were obtained. The ligands were characterized by elemental analysis, Fourier transform-infrared (FT-IR) ultraviolet-visible NMR (¹H, ¹³C, and heteronuclear multiple-bond correlation) and electrospray ionization (ESI) mass spectrometry. The isolated complexes were characterized by a combination of elemental analysis, IR, UV-vis, and ESI mass spectrometry and in the case of Ni(II) and Zn(II) complexes by ¹H and ¹³C NMR spectroscopy. The electrochemical behaviors of the ligands and their complexes were studied by cyclic voltammetry (CV) in dimethylsulfoxide solution containing tetrabutylammoniumtetrafluoroborate (TBATFB). The antibacterial activity was also studied against S. aureus ATCC 25923, S. aureus ATCC 29213, S. mutans RSHM 676, E. faecalis ATCC 29212, E. coli ATCC 25922, and P. aeruginosa ATCC 27853. The antimicrobial test results indicated that all the compounds have good antibacterial activity against P. auriginosa ATCC 27853 bacteria and were as effective as ampicilin. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications for the following free supplemental resources: Full experimental and spectral details.]

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Preparation and Spectral and Biological
Investigation of vic-Dioxime Ligands
Containing Piperazine Moiety and Their
Mononuclear Transition-Metal Complexes
Bilge Taner a & Uğur Arslan b
a Department of Chemistry, Faculty of Science , Selcuk University ,
Konya , Turkey
b Department of Clinical Microbiology, Selcuklu Medical Faculty ,
Selcuk University , Konya , Turkey
Accepted author version posted online: 03 Jul 2013.Published
online: 05 Sep 2013.
To cite this article: Bilge Taner & Uğur Arslan (2013) Preparation and Spectral and Biological
Investigation of vic-Dioxime Ligands Containing Piperazine Moiety and Their Mononuclear Transition-
Metal Complexes, Synthetic Communications: An International Journal for Rapid Communication of
Synthetic Organic Chemistry, 43:24, 3307-3314, DOI: 10.1080/00397911.2013.777743
To link to this article: http://dx.doi.org/10.1080/00397911.2013.777743
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Synthetic Communications1, 43: 3307–3314, 2013
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2013.777743
PREPARATION AND SPECTRAL AND BIOLOGICAL
INVESTIGATION OF VIC-DIOXIME LIGANDS
CONTAINING PIPERAZINE MOIETY AND THEIR
MONONUCLEAR TRANSITION-METAL COMPLEXES
1
Bilge Taner and Ugur Arslan
2
˘
1Department of Chemistry, Faculty of Science, Selcuk University,
Konya, Turkey
2Department of Clinical Microbiology, Selcuklu Medical Faculty,
Selcuk University, Konya, Turkey
GRAPHICAL ABSTRACT
Abstract Two vic-dioxime ligands, N-(4-benzylpiperazine-1-yl) p-tolylglyoxime (L1H2) and
N,N0-bis(4-benzylpiperazine-1-yl) glyoxime (L2H2), containing piperazine moieties were
synthesized, and their Ni(II), Cu(II), Co(II) and Zn(II) complexes were obtained. The ligands
were characterized by elemental analysis, Fourier transform–infrared (FT-IR), ultraviolet–
visible NMR (1H, 13C, and heteronuclear multiple-bond correlation), and electrospray ioniza-
tion (ESI) mass spectrometry. The isolated complexes were characterized by a combination of
elemental analysis, IR, UV-vis, and ESI mass spectrometry and in the case of Ni(II) and
Zn(II) complexes by 1H and 13C NMR spectroscopy. The electrochemical behaviors of the
ligands and their complexes were studied by cyclic voltammetry (CV) in dimethylsulfoxide
solution containing tetrabutylammoniumtetrafluoroborate (TBATFB). The antibacterial
activity was also studied against S. aureus ATCC 25923, S. aureus ATCC 29213, S. mutans
RSHM 676, E. faecalis ATCC 29212, E. coli ATCC 25922, and P. aeruginosa ATCC
27853. The antimicrobial test results indicated that all the compounds have good antibacterial
activity against P. auriginosa ATCC 27853 bacteria and were as effective as ampicilin.
Received January 17, 2013.
Address correspondence to Bilge Taner, Selcuk University, Faculty of Science, Department of
Chemistry, Konya, Turkey. E-mail: bilgetaner@gmail.com
3307

3308
B. TANER AND U. ARSLAN
[Supplementary materials are available for this article. Go to the publisher’s online
edition of Synthetic Communications1 for the following free supplemental resources: Full
experimental and spectral details.]
Keywords Antimicrobial activity; cyclic voltammetry; 1D and 2D NMR; piperazine;
vic-dioxime
INTRODUCTION
vic-Dioxime ligands have remained an important and popular area of research
because of their simple synthesis, versatility, and diverse range of applications.[1–13]
Because of the high stability of vic-dioxime complexes, they have been shown to
be useful in many research areas such as medicine,[14] catalysis,[15] electrochemical
and electrooptical sensors,[16] biomimetic enzyme models,[17] and technological
applications.[18,19]
Like oximes, piperazine and substituted piperazine are important pharmaco-
phores that can be found in biologically active compounds across a number of dif-
ferent therapeutic areas,[20] such as antifungal,[21] antibacterial, antimalarial, and
anti-psychotic agents;[22] HIV protease inhibitor;[23,24] antidepressants; and antitu-
mor agents against colon, prostate, breast, lung, and leukamia tumors. Thus, the
broad pharmacological interest in oxime and piperazine derivatives and their great
potential for important applications includes the attachment of a piperazine moiety
on a vic-dioxime compound, which can lead to new vic-dioxime derivatives with
important pharmacological properties (Scheme 1). Macit and coworkers synthesized
4-benzyl-1-piperazineglyoxime ligand and Ni(II), Cu(II), and Co(II).[25] In previous
work[26] synthesis and characterization of a new vic-dioxime ligand bearing pipera-
zine moiety and its Ni(II) complex were reported. In this article, the structure of
the vic-dioxime ligands, N-(4-benzylpiperazine-1-yl) p-tolylglyoxime (L1H2) and
N,N0-bis(4-benzylpiperazine-1-yl) glyoxime (L2H2), are characterized in detail for
the first time to confirm the proposed structure by means of elemental analysis,
Fourier transform–infrared (FT-IR), ultraviolet–visible (UV-vis), mass spectrometry
Scheme 1. Synthesis of the vic-dioxime ligands (L1H2 and L2H2): (i) EtOH, rt, 3 h; (ii) EtOH, Ar, rt, 24 h.

vic-DIOXIME LIGANDS
3309
1
(MS), H NMR, 13C NMR, and heteronuclear multiple-bond correlation (HMBC)
techniques. All of complexes have been characterized by elemental analysis, IR spec-
1
tra, UV-vis, and, in the case of Ni(II) and Zn(II) complexes, by H and 13C NMR
spectroscopy. The cyclic voltammetric measurements of the metal complexes have
also been studied to understand the electrochemical behavior of their reduced or oxi-
dized species in nonaqueous solution. Because of the broad spectrum of biological
properties of piperazine and vic-dioxime, we thought it would be worthwhile study-
ing the structures and antimicrobial activities of vic-dioxime ligands and their metal
complexes, and we report the results of this investigation here. To the best of our
knowledge, this is the first report that includes enhanced characterization,
electrochemical property, and antibacterial activity of L1H2 and L2H2 and their
metal complexes.
RESULTS AND DISCUSSION
The ligands L1H2 and L2H2 were obtained according to Scheme 1, and the
characterization of the formed compounds were performed by elemental analysis,
FT-IR, UV-vis, one-dimensional (1D) NMR (1H, 13C), two-dimensional (2D)
NMR (HMBC), and ESI mass spectrometry. The isolated complexes were character-
ized by a combination of elemental analysis, ESI mass spectrometry, IR, magnetic
susceptibility measurements, and, in the case of Ni(II) and Zn(II) complexes, by
1H and 13C NMR spectroscopy. Experimental results of the elemental analyses of
the synthesized ligands and their metal chelates were in good agreement with theor-
etical expectations. Elemental analyses and ESI mass spectrometry of the complexes
indicated that the metal–ligand ratios were 1:2, 1:2, and 1:1 for the [M(LH)2]
[M ¼ Ni(II) or Cu(II)], [M(LH)2(H2O)2] [M ¼ Co(II)], and [M(LH2)(OH)2] [M ¼
Zn(II)] metal complexes, respectively (Fig. 1).
In IR spectra, the vic-dioxime ligands (L1H2 and L2H2) showed characteristic
=
stretching vibrations due to OꢀH, C N, and NꢀO stretches at 3250–3280,
1654–1597, and 969–987 cmꢀ1, respectively.[27,28] The bands for C N groups present
=
in all the complexes are distinct and occur within 1568–1625 cmꢀ1. The shift of the
Figure 1. Proposed structure of the Ni(II), Cu(II), Co(II), and Zn(II) complexes of L1H2 and L2H2.

3310
B. TANER AND U. ARSLAN
=
C N band of the ligands to a low frequency supports the suggestion of coordination
through the imine nitrogen atoms.[29] The IR spectra of Ni(II), Cu(II), and Co(II)
complexes display weak deformation bands at 1765–1727 cmꢀ1, indicative of intra-
molecular hydrogen-bonded bending vibrations (OꢀH. . .O) associated with the
square-planar and octahedral vic-dioxime complexes. In addition, the presence of
the water molecules was confirmed by the appearance of a broad band centered
about 3400–3300 cmꢀ1 in the IR spectrum of the [Co(L1H)2(H2O)2] and
[Co(L2H)2(H2O)2].[12] In the Zn(II) complexes of L1H2 and L2H2, two of the four
coordination sites of the metal ions were occupied by two nitrogen atoms of the
dioxime molecule; the other two groups were hydroxyl ions. In the IR spectra the
Zn(II) complexes showed that v (OꢀH) vibrations were unchanged as they were
in the ligands.[9] The C N absorptions were slightly lower than those of the
=
vic-dioximes and were consistent with N,N-chelate coordination.
The 1H NMR spectral results obtained for L1H2 and L2H2 ligands in
dimethylsulfoxide (DMSO-d6), together with the assignments, are given in the
Experimental section. In the 1H NMR spectrum of L1H2, the deuterium
=
exchangeable protons of the NꢀOH groups show chemical shifts at 11.45
and 9.16 ppm. These two D2O-exchangeable singlets correspond to two nonequi-
valent ꢀOH protons, which also indicate the anti configuration of the ꢀOH rela-
tive to each other.[4,5,27] The first one is assigned to the ꢀOH proton on the phenyl
side with the latter to the ꢀOH proton of the piperazine group because the effect of
1
various substituents is expected to be greater on the piperazine group. In the H
NMR spectrum of L2H2, the deuterium exchangeable protons of the NꢀOH
=
groups show only one chemical shifts at d ¼ 9.87ppm as a singlet, which indicates
an (E; E) structure for the vicinal dioxime.[28,29] The chemical shifts that belong to
ꢀCH2 protons were observed at d ¼ 3.43ppm (ArꢀCH2ꢀN) as a singlet, 3.01ppm
(CH2ꢀ) and 2.27ppm (CH2ꢀ) as a triplet for L1H2, and at d ¼ 3.48ppm
(ArꢀCH2ꢀN) as a singlet, 3.27ppm (CH2ꢀ) and 2.38ppm (CH2ꢀ) as a triplet for
L2H2. The chemical shifts that belong to aromatic protons were observed at
7.51–7.19 ppm for L1H2 and 7.35–7.21ppm for L2H2. More detailed information
about the structure of L1H2 and L2H2 ligands are provided by 13C NMR spectral
data and HMBC spectrum (Fig. S1, Supplementary Material) and specific assign-
ments of protons and carbons are made as seen in Table S1. The HMBC spectrum
of L1H2 (Fig. S1a) shows that Ha and Hb protons exhibit long-range coupling with
hydroxyimino carbons at 155.73 (C8) and 150.27 (C9) ppm, respectively. In the 13C
NMR of L2H2, the carbon resonances of oxime groups are observed at 147.22ppm.
These equivalent carbon atoms, especially belonging to hydroxyimino carbon atoms,
also confirm the anti structure of L2H2. Other correlations are also in accordance
with the proposed structures (Table S1). The mass spectra of L1H2 and L2H2 ligands
were obtained by the electrospray ionization and mass spectrometry (ESI=MS) tech-
nique and they showed molecular ion peaks at m=z ¼ 353.39 (MH)þ for L1H2 and
m=z ¼ 436.59 (M)þ for L2H2.
The formation of Ni(II) and Zn(II) complexes are conveniently monitored by
1
1H NMR and 13C NMR spectroscopy. The H NMR of [Ni(L1H)2] shows a singlet
at 16.24 ppm, with a chemical shift comparable to that observed for [Ni(L2H)2],
which shows a signal at 15.32 ppm. These signals could be identified easily by
means of a deuterium exchange or they could be assigned to the formation of

vic-DIOXIME LIGANDS
3311
a hydrogen bridge.[30] In the 1H NMR spectrum of [Zn(L1H2)(OH)2] and
[Zn(L2H2)(OH)2] the aromatic ring protons are observed at 7.33 ppm and
7.17 ppm for [Zn(L1H2)(OH)2] and 7.33 ppm and 7.23 ppm for [Zn(L2H2)(OH)2]
1
as multiplets. In the H NMR spectrum of these complexes, peaks corresponding
to NꢀOH were observed at 11.81 ppm and 8.44 ppm for [Zn(L1H2)(OH)2] and
10.04 ppm for [Zn(L2H2)(OH)2]. In the 13C NMR spectra of [Zn(L1H2)(OH)2]
and [Zn(L2H2)(OH)2] quaternary carbon signals of the hydroxyiminocarbon
(C NꢀO) appeared at 148.04 and 140.85 ppm for [Zn(L1H2)(OH)2] and
=
153.07 ppm for [Zn(L2H2)(OH)2]. The other 13C NMR chemical shifts observed
for these complexes are very similar to those found for ligands. Becuase the Co(II)
and Cu(II) complexes are paramagnetic, their NMR spectra could not be obtained.
The Co(II) complexes were characterized by IR, ESI-MS, and elemental analyses
and it was found that two molecules of water were axially coordinated to the cobalt
ion. The observation of an (OꢀH. . .O) bond leads us to consider the geometry of
complexes to be octahedral.
To understand the effects of different transition-metal ions on the optical
properties of the ligands, we measured the absorption spectra of L1H2 and L2H2
and their mononuclear complexes. The electronic spectra of all the compounds were
recorded in DMSO solution (Fig. S2). The ligand (L1H2 and L2H2) absorption spec-
tra reveal bands at about 264 nm, which can be assigned to p ! pꢁ transitions of the
aromatic rings.[6] In the spectra of the [Ni(L1H)2] and [Ni(L2H)2] compounds, two
bands at about 345 nm and 417 nm for [Ni(L1H)2] and 377 nm and 474 nm for
[Ni(L2H)2] may originate from the ligand-to-metal charge-transfer (LMCT) and
d–d transition,[31] respectively. Because no other d–d bands are observed at up to
1200 nm, the simplicity of the spectra and the corresponding band intensities suggest
a square planar, rather than tetrahedral, configuration of the complex in the sol-
ution.[6] The weak d–d transition of the Cu(II) and Co(II) complexes could not be
observed. The d–d bands should also be present in this range with low intensities,
but they are masked by the stronger CT absorption band.[12]
The electrochemical properties of the novel vic-dioxime ligands and their metal
complexes were investigated by cyclic voltammetry in the potential range of 1 to ꢀ
2.5 V versus Ag=AgCl in DMSO medium using 0.1 M tetrabutylammoniumtetra-
fluoroborate (TBATFB) as the supporting electrolyte at a 50 mV sꢀ1 scan rate (Figs.
S3 and S4).
The vic-dioxime ligands (L1H2 and L2H2) exhibit a one-electron quasireversible
reduction and oxidation process in DMSO medium. The DEp values of L1H2 and
L2H2 are 1.93 and 2.35 V versus Ag=AgCl, respectively. Comparison of redox data
of ligands with previously reported oxime–metal complexes[6,12] imply that the
oxidations and the reduction correspond to the oxime moieties.
The large peak separations between the reduction and its re-oxidation wave are
probably due to the coupled chemistry following the electrode reaction. [Ni(L1H)2]
complex displays two cathodic reversible waves corresponding to the successive
one-electron reduction steps [Ni(II)=Ni(I) and Ni(I)=Ni(0)], while the [Ni(L2H)2]
complex display corresponds to the Ni(II)=Ni(I) redox processes. The redox process
of the metal centered in vic-dioxime complexes are mostly observed at more positive
values than that of the ligand-based process.[11] For the Cu(L2H)2 complex, the
reversible wave at E1=2 ꢀ0.39 V and a reversible peak at ꢀ0.40 V correspond to

3312
B. TANER AND U. ARSLAN
the Cu(II)=Cu(I) and Cu(I)=Cu(0) couples, respectively, in addition to the ligand
peaks at ꢀ2.03 V. The reversible character indicates that both Cu(II) and Cu(I) com-
plexes of L2H2 are stable at the electrode surface and in DMSO.[6] However, in the
case of [Cu(L1H)2] complex, a quasireversible peak is observed at E1=2 ꢀ0.64 V and
corresponds to Cu(II)=Cu(I). The cobalt complexes [Co(L1H)2(H2O)2 and
Co(L2H)2(H2O)2] showed one oxidation and one reduction process. Their cathodic
peak potentials of the reduction processes are at Epc ¼ ꢀ1.27 and ꢀ0.56 V and their
half-wave peak potentials of the oxidation processes are at E1=2 ¼ ꢀ1.14 and
ꢀ0.28 V, respectively, versus Ag=AgCl at a 50 mV sꢀ1 scan rate (Table S2). These
complexes give a one-electron Co(II)=Co(I) couple with a high peak separation,
probably due to
a
slow charge transfer process.[8] [Zn(L1H2)(OH)2] and
[Zn(L2H2)(OH)2] show a cyclic voltammetry (CV) voltammogram in line with expec-
tations. In these complexes, the cyclic voltammetric Zn(II)=Zn(I) reduction process
was observed at
ꢀ0.73 V and ꢀ1.70 V and oxime group reductions were observed at ꢀ1.65 V and ꢀ
2.01 V, respectively.[12] It is clearly stated in the literature that oxime-containing
metal complexes give redox signals involving both higher and lower oxidation states
of the metal depending on the coordination environment of metal center.[6,8,11] For
all complex CV measurements, at different scan rates in the range of 50–800 mV sꢀ1
,
the Epc values appear to be only slightly dependent upon the scan rate. Further-
more, in all cases a linear relationship between the cathodic peak current (ipc) and
the square root of the scan rate was observed. This fact implies that these electro-
chemical processes are mainly diffusion controlled.
A screening of antibacterial activities with six bacteria [S. aureus ATCC 25923,
S. aureus ATCC 29213, S. mutans RSHM 676, E. faecalis ATCC 29212, E. coli
ATCC 25922, and P. aeruginosa ATCC 27853] was performed and the minimum
inhibitory concentrations (MICs in mg=mL) were determined (Table S3). MICs were
found for the novel vic-dioxime ligands and their metal complexes, ranging from
32 mg=ml to 128 mg=ml. The main reason for the antimicrobial activity in compounds
L1H2 and L2H2 is related to the presence of piperazine.[26] In light of these results, it
appears that compounds L1H2 and L2H2 showed the same antimicrobial activity
against tested microorganisms. A comparative study of the MICs values for the
ligands and their complexes indicates that the free ligand is less active against bacter-
ias (S. aureus ATCC 25923, S. aureus ATCC 29213, S. mutans RSHM 676, E. fae-
calis ATCC 29212, E. coli ATCC 25922, and P. aeruginosa ATCC 27853)
compared to the metal complexes. When examining the effectiveness of the com-
pounds against the Pseudomonas aeruginosa bacteria, all compounds were as effec-
tive as ampicilin.[6] In particular, vic-dioxime complexes have lower MIC values
than ampicilin. It was evident from the data that the antimicrobial activity of the
vic-dioxime ligands was increased on coordination. The chelation=coordination
reduces the polarity of the metal ion through a partial sharing of its positive charge
with the donor groups and possibly p-electron delocalization within the whole che-
late ring. This process thus increases the lipophilic nature of the central metal atom
which, in turn, favors its greater penetration through the bacterial wall of the micro-
organisms, thus killing them more effectively.[31] It has also been observed that the
solubility, conductivity, and dipole moment are also influenced by the presence of
metal ions; these could be the significant factors responsible for increasing the

vic-DIOXIME LIGANDS
3313
hydrophobic character and liposolubility of the molecule, hence enhancing the
biological activity. The present investigations of antimicrobial screening data
revealed that the newly synthesized compounds exhibited mild activity compared
to that of the control drugs.[21,22,26]
In summary, we have described the preparation, characterization, and biologi-
cal activities of two vic-dioxime ligands and the Ni(II), Cu(II), Co(II), and Zn(II)
metal complexes that were substituted peripherally with the piperazine moiety.
Antimicrobial activities of newly synthesized compounds were investigated against
some Gram-positive and Gram-negative bacteria such as S. aureus ATCC 25923, S.
aureus ATCC 29213, S. mutans RSHM 676, E. faecalis ATCC 29212, E. coli ATCC
25922, and P. aeruginosa ATCC 27853. The antibacterial data given for the com-
pounds presented in this article allowed us to state that the vic-dioxime complexes
generally show very little antibacterial activity and all the compounds have good
antibacterial activity against P. aeruginosa ATCC 27853 bacteria, which is as
effective as ampicilin.
EXPERIMENTAL
The L2H2 and its complexes were prepared according to described procedures
(Supporting material).
Synthesis of the New Ligand
1-Benzylpiperazine (0.35 mL, 2 mmol) was dissolved in absolute ethanol
(15 mL), and the solution containing anti-chloro-p-tolylglyoxime (0.22 g, 1 mmol), in
absolute ethanol (20 mL), was added slowly to this solution at room temperature with
constant stirring. The reaction mixture was stirred continuously for 3 h at room tem-
perature. Water was added dropwise until a white precipitate formed. The precipitated
ligand was filtered off, washed with cold water, dried, and crystallized from water–
ethanol (1:3). The ligand is soluble in ethanol, DMSO, and dimethylformamide.
Synthesis of the New Metal Complexes, General Procedure
A solution of NiCl2 ꢂ 6H2O (0.059 g, 0.25 mmol), CuCl2 ꢂ 2H2O (0.043 g,
0.25 mmol), CoCl2 ꢂ 6H2O (0.059 g, 0.25 mmol), or ZnCl2 (0.07 g, 0.50 mmol) in water
(5 mL) was added to a solution of L1H2 (0.18 g, 0.50 mmol) or L2H2(0.22 g,
0.50 mmol) in 5 mL of ethanol at room temperature. A distinct change in color
and a decrease in the pH of the solution (3.5–4.0) were observed for Ni(II), Cu(II),
and Co(II) complexes. While stirring at the same temperature, ethanolic NaOH (1%)
was added to increase the pH to 6.0–6.5. The reaction mixture was stirred for 30 min
at room temperature. The precipitates were then filtered and washed with water,
ethanol, and ether and then dried in vacuo.
ACKNOWLEDGMENT
This work was supported the Research Fund of Selcuk University, Project
Number 12401020.

3314
B. TANER AND U. ARSLAN
REFERENCES
1. Chakravorty, A. Coord. Chem. Rev. 1974, 13, 1.
2. Canpolat, E.; Kaya, M. Turk. J. Chem. 2004, 28, 235.
¨
3. Ozer, M.; Kandaz, M.; Ozkaya, A. R.; Bulut, M.; Guney, O. Dyes Pigments 2008, 76,
¨
¨
125–132.
˙
4. Yuksel, F.; Gurek, A. G.; Durmus¸, M.; Gurol, I.; Ahsen, V.; Jeanneau, E.; Luneau, D.
¨
Inorg. Chim. Acta 2008, 361, 2225–2235.
¨
¨
5. Taner, B.; Deveci, P.; Bereket, S.; Solak, A. O.; Ozcan E. Inorg. Chim. Acta 2010, 363,
4017–4023.
6. Deveci, P.; Arslan, U. J. Organmet. Chem. 2011, 696, 3756–3763.
7. Hall, I. H.; Bastow, K. F.; Warren, A. E. Appl. Organomet. Chem. 1999, 13, 819–828.
8. Gupta, B. D.; Yamuna, R.; Debaprasad, M. Organometallics 2006, 25, 706–714.
˙
9. Kurtog˘lu, M.; Ispir, E.; Kurtog˘lu, N.; Serin, S. Dyes Pigments 2008, 77, 75–80.
10. Dutta, G.; Kumar, K.; Gupta, B. D. Organometallics 2009, 28, 3485–3491.
˙
11. Kılıc¸, A.; Tas¸, E.; Yılmaz, I. J. Chem. Sci. 2009, 121, 43–56.
¨
12. Deveci, P.; Taner, B.; Kılıc¸, Z.; Solak, A. O.; Arslan, U.; Ozcan, E. Polyhedron 2011, 30,
1726–1731.
13. Schrauzer, G. N.; Kohnle, J. Chem. Ber. 1964, 97, 3056.
14. Musilova, L.; Kuca, K.; Jung, Y. S. Jun. D. Clin. Toxicol. (Phila.) 2009, 47, 545.
15. Malmstro¨m, B. G. Acc. Chem. Res. 1993, 26, 332–338.
16. Sevagapandian, S.; Rajagopal, G.; Nehru, K.; Athappan, P. Transition Met. Chem. 2000,
25, 388–393.
17. Mokhir, A.; Kra¨mer, R.; Voloshin, Y. Z.; Varzatskii, O. A. Bioorg. Med. Chem. Lett.
2004, 14, 2927–2930.
18. Ozkaya, A. R.; Okur, A. I.; Gul, A.; Bekarog˘lu, O. J. Coord. Chem. 1994, 33, 311–318.
19. Ozkaya, A. R.; Yilmaz, I.; Bekarog˘lu, O. J. Porhyr. Phthalocya 1998, 2, 483–492.
20. Berkheij, M. Tetrahedron Lett. 2005, 15, 2369–2371.
21. Upadhayaya, R. S.; Sinha, N.; Jain, S.; Kishore, N.; Chandra, R.; Arora, S. K. Bioorg.
Med. Chem. 2004, 12, 2225–2238.
22. Chaudhary, P.; Kumar, R.; Singh, D.; Yadav, V.; Chhiller, A.; Sharma, G. L.; Verma,
A. K. Bioorg. Med. Chem. 2006, 14(6), 1819–26.
23. Askin, D.; Eng, K. K.; Rossen, K.; Purick, R. M.; Wells, K. M.; Volante, R. P.; Reider,
P. J. Tetrahedron Lett. 1994, 35, 673.
24. Rossen, K.; Weissman, S. A.; Sagar, J.; Reamer, A.; Aksin, D. A.; Volante, R. P.; Reider,
P. J. Tetrahedron Lett. 1995, 36, 6419.
25. Macit, M.; Bati, H.; Bati, B. Synth. React. Inorg. Met.-Org. Chem. 1998, 28, 833–841.
˙
26. Yılmaz, A.; Taner, B.; Deveci, P.; Yılmaz Obalı, A.; Arslan, U.; S¸ahin, E.; Uc¸an, H. I.;
¨
Ozcan, E. Polyhedron 2010, 29, 2991–2998.
˙
27. Kurtog˘lu, M.; Ispir, E.; Kurtog˘lu, N.; Torog˘lu, S.; Serin, S. Transition Met. Chem. 2005,
30, 765–770.
28. Pedersen, S. B.; Larsen, E. Acta Chem. Scand. 1973, 27, 3291.
29. Durmus¸, M.; Ahsen, V.; Luneau, D.; Pecaut, J. Inorg. Chim. Acta 2004, 357, 588–594.
˙
30. Tas¸, E.; Kara, H.; Durgun, M.; Kılıc¸, A.; Yılmaz, I. Synth. React. Inorg. Met. Org. Chem.
2009, 39, 379–387.
31. Tumer, M.; Ko¨ksal, H.; S¸ener, M. K.; Serin, S. Transition Met. Chem. 1999, 24, 414–420.
¨