A mononuclear cobalt(III) complex and its catecholase activity

Article abstract of DOI:10.1039/c4nj01587h

The structural analysis of a cobalt(III) complex [Co(HL)₂](OAc)·H₂O (1) [H₂L = N-(2-hydroxyethyl)-3-methoxysalicylaldimine] reveals a tridentate chelation behaviour of the ligand H₂L having a distorted octahedra

Full text of DOI:10.1039/c4nj01587h

View Article Online
View Journal
NJC
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: R. Ghosh, M. Mitra
and P. Raghavaiah, New J. Chem., 2014, DOI: 10.1039/C4NJ01587H.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/njc

Page 1 of 6
New Journal of Chemistry
View Article Online
DOI: 10.1039/C4NJ01587H
Table of Contents
A mononuclear cobalt(III) complex and its catecholase
activity
Merry Mitra,a Pallepogu Raghavaiahb,c and Rajarshi Ghosh*a
a Department of Chemistry, The University of Burdwan, Burdwan 713 104, India.
Fax: +91-342-2530452; Tel: +91 342 2533913 ext: 424; E-mail:
rajarshi_chem@yahoo.co.in.
b Department School of Chemistry, University of Hyderabad, Hyderabad 500 046, India
c Present address: Department of Chemistry, Dr. Harisingh Gour University, Sagar 470 003,
India
Graphical Abstract
A mononuclear Co(III) complex is mimicking the catechol oxidase enzyme with appreciably
high turnover numbers in different solvents.

View Article Online
DOI: 10.1039/C4NJ01587H
New Journal of Chemistry
Page 2 of 6
Dynamic Article Links ►
NJC
Cite this: DOI: 10.1039/c0xx00000x
www.rsc.org/xxxxxx
PAPER
A mononuclear cobalt(III) complex and its catecholase activity
Merry Mitra,a Pallepogu Raghavaiahb,c and Rajarshi Ghosh*a
Received (in XXX, XXX) Xth XXXXXXXXX 20XX, Accepted Xth XXXXXXXXX 20XX
DOI: 10.1039/b000000x
5
Structural analysis of a cobalt(III) complex [Co(HL)2](OAc).H2O (1) [H2L = N-(2-hydroxyethyl)-3-
methoxysalicylaldimine] reveals tridentate chelation behaviour of the ligand H2L having a distorted
octahedral coordination environment around the cobalt(III) center with a CoN2O4 chromophore. 1
behaves as an effective catalyst towards oxidation of 3,5-di-tert-butylcatechol in different solvents, viz.
dichloromethane (DCM), methanol (MeOH) and acetonitrile (MeCN) to its corresponding quinone
10 derivative in aerial oxygen. The reaction follows Michaelis-Menten enzymatic reaction kinetics with
turnover numbers (Kcat), 1.46 × 103, 1.21 × 103 and 2.16 × 103 h-1 in DCM, MeOH and MeCN,
respectively.
yet to be appeared indicating the necessity of modeling
catecholase active complexes. Here, in this endeavor, we report
40 the synthesis and characterization of a mononuclear cobalt(III)
complex (1),13 with an (N,O) donor Schiff base ligand and its
catalytic activity towards oxidation of a catechol derivative to its
corresponding quinone in different solvents.
Introduction
In plant system, catalysis of oxidation of o-diphenol (catechol) to
15 corresponding quinone coupled with 2e/2H+ reduction of oxygen
to water, in presence of molecular oxygen is known as
catecholase activity. The resulting quinones autopolymerize to
give brown pigments which are responsible to defense the
damage caused by the pathogens and insects in plants. The crystal
20 structure of the met form of the enzyme catechol oxidase, also
known as o-diphenol oxidase, contains two hydroxobridged
strongly antiferromagnetically coupled copper(II) centres in their
active site. The each copper(II) centre is coordinated to three
histidine nitrogens and adopts a trigonal pyramidal environment
25 with one nitrogen in the apical site. Since the elucidation of its
crystal structure1 several reports of dicopper(II) complexes have
been found2-5 to correlate the structure-function relationship of
this biocatalytic reaction. Moreover, different monocopper(II),6
Experimental
45 Materials
High purity o-vanillin (Aldrich, UK), 2-aminoethanol (Aldrich,
UK), cobalt(II) acetate tetrahydrate (Aldrich, UK), 3,5-di-tert-
butylcatechol (Aldrich, UK) and all other solvents were
purchased from the respective concerns and used as received.
50 Solvents were dried according to standard procedure and distilled
prior to use.
The
ligand
H2L
[H2L
=
N-(2-hydroxyethyl)-3-
reported
methoxysalicylaldimine] was prepared using
a
manganese(III),6e,7
nickel(II),8
nickel(II)-manganese(II),9
procedure.14 O-vanillin (0.3043 g, 2 mmol) was heated under
55 reflux with 2-aminoethanol (0.1222 g, 2 mmol) in 30 ml
dehydrated ethanol. After 2 h, the reaction solution was
evaporated under reduced pressure to yield a yellow coloured
solid, which was dried under vacuum and stored over CaCl2 for
subsequent use.
30 Fe(III),10 cobalt(II/III)11 and zinc(II)12 compounds are available
which show catecholase activity. All these indicate that the
exploration of the possibility of catecholase activity by new types
of species with different ligand environment, and different metal
ions along with their different oxidation state(s) and nuclearity,
35 that can mimic the native enzyme, deserves special importance.
The exact structure-property correlation for catecholase activity is
____________________________________________________
60
For catecholase activity study, 1 × 10-4 mol dm-3 solution of 1
(0.0005 g) was treated with 1 × 10-2 mol dm-3 (100 equivalents)
of 3,5-DTBC (0.0222 g) under aerobic conditions.
a Department of Chemistry, The University of Burdwan,
Burdwan 713 104, India. Fax: +91-342-2530452;
Physical measurements
Tel: +91 342 2533913 ext: 424; E-mail: rajarshi_chem@yahoo.co.in.
Department School of Chemistry, University of Hyderabad,
Elemental analyses (carbon, hydrogen and nitrogen) were
b
65 performed on a Perkin-Elmer 2400 CHNS/O elemental analyzer.
UV-Vis and IR spectra (KBr discs, 4000-300 cm-1) were recorded
using a Shimadzu UV-Vis 2450 spectrophotometer and Perkin-
Elmer FT-IR model RX1 spectrometer, respectively. The H1
NMR spectral data were collected in CDCl3 on a Bruker 400
70 MHz spectrometer. Mass spectrometric data were collected on
Hyderabad 500 046, India.
c
Present address: Department of Chemistry, Dr. Harisingh Gour
University, Sagar 470 003, India
† Electronic Supplementary Information (ESI) available: [magnetic
and
spectroscopic
plots
are
included
here].
See
DOI: 10.1039/b000000x/
This journal is © The Royal Society of Chemistry [year]
[journal], [year], [vol], 00–00 | 1

View Article Online
DOI: 10.1039/C4NJ01587H
Page 3 of 6
New Journal of Chemistry
Xevo G2 Q TOF mass spectrometer.
data and refinement details are listed in Table 1. The structure
was solved by direct methods, and the structure solution and
refinement were based on |F|2. The final differences Fourier map
showed the maximum and minimum peak heights at 0.575 and -
25 0.364 eÅ-3 with no chemical significance. All calculations were
carried out using SHELXL-9715 and were refined using SHELSL-
97.15 All the figures have been generated using ORTEP-32.16
Preparation of 1
A methanolic solution (5 cm3) of Co(OAc)2.4H2O (0.0623 g, 0.25
mmol) was added dropwise to a stirring solution of H2L (0.0244
g, 0.125 mmol) in DCM (10 cm3). The brown solution with
reddish tinge was filtered and the supernatant liquid was kept in
air for slow evaporation. The product was obtained as square
deep brown solid.
5
Results and Discussion
Yield: (based on metal salt) 0.1126 g (86.22%). Anal. calc. for
Synthesis and formulation
10 C22H27N2O9Co (1): C, 50.58; H, 5.21; N, 5.36; Found: C, 50.32;
H, 4.90; N, 4.92. Selected IR bands (KBr pellet, cm-1): 3461 (s),
1655 (s), 1648 (s), 973 (s). UV-Vis (λ, nm): 252, 390, 495 and
751.
30 Complex 1 was synthesized by addition of methanolic solution of
Co(II) acetate tetrahydrate into the dichloromethane solution of
the ligand H2L.
The compound was characterized using elemental analysis, IR,
UV, NMR and single crystal X-ray crystallography. IR spectrum
35 of 1 shows relatively intense peaks around 1590–1600 cm-1 due
to the C=N stretching frequency and weak bands in the range
2980–2900 cm-1 due to the aliphatic C–H stretching.
X-ray diffraction study
15 Single crystals of 1 suitable for X-ray crystallographic analysis
was selected following examination under
Diffraction data was collected at 293(2) K on a Bruker SMART
APEX  CCD diffractometer using Mo-Kα radiation (λ =
0.71073 Å) and was identified as P 21/c space groups. The crystal
a microscope.
X-ray structure
The molecular structure of 1 is shown in Fig. 1. X-ray
40 crystallography reveals (Table 1) that the hexacoordination
around the Co(III) centre is completed by the N and O donor
centres from each of the organic ligand frameworks.
20 Table 1 Crystal data and structure refinement parameters for 1.
Empirical formula
C22H27N2O9Co
522.39
Formula weight
T (K)
293(2)
Wavelength (Å)
0.71073
Monoclinic
P21/c
Crystal system
Space group
Unit cell dimensions
a (Å))
15.959(5)
11.194(3)
13.281(4)
90.00
b (Å)
c (Å)
α (°)
β (°)
100.678(5)
90.00
γ (°)
V (Å3)
2331.4(12)
4
Z
Dcalc (mg/m3)
1.488
Absorption coefficient (mm-1)
0.791
F(000)
1088
Crystal size (mm3)
Theta range for data collection
(°)
0.36×0.21×0.09
1.30-25.97
Fig. 1 ORTEP diagram of 1 with 20% ellipsoid probability plot.
Index ranges
-19 ≤ h ≤ 19, -13 ≤ k ≤13, -16 ≤ l
≤16
45
The diamagnetic behavior (Fig. S1; Supporting Information) as
well as comparison of the bond angle-bond distance parameter
(Table 2) of the complex with other reported ones confirms the
oxidation state of the metal as +III. The phenolic OH in the
ligand framework gets deprotonated13 because of its higher
Reflections collected
Independent reflections
Completeness to theta
Absorption correction
Tmax and Tmin
23447
4563 [Rint = 0.0356]
99.8% (θ = 25.97)
Multi-scan
0.9322 and 0.7638
full-matrix least-squares on F2
4563/2/318
50 acidity than alcoholic OH, hence the monocationic [Co(HL)2]+ is
being formed. The positive charge of the complex is neutralized
by a crystallized acetate anion. The geometry around metal(III)
centre is best described as distorted octahedron. Bond angle and
bond distance data (Table 2) reveal that the phenolic oxygen O1
55 and the alcoholic oxygen O2 are at the axial position of the
octahedron. The rest N1, N2 (imine nitrogens) and O3 (phenolic
oxygen), O4 (alcoholic) are at axial position.
Refinement method
Data/restraints/parameters
Goodness-of-fit (GOF) on F2
Final R indices [l > 2σ(l)]
R indices (all data)
1.063
R1 = 0.0556, wR2 = 0.1456
R1 = 0.0672, wR2 = 0.1542
0.575, -0.364
Largest difference in peak and
hole(e Å-3)
2
| Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

View Article Online
New Journal of Chemistry
DOI: 10.1039/C4NJ01P58a7gHe 4 of 6
Table 2 Bond lengths [Å] and angles [°] for 1.
3,5-DTBC and 1, the reaction kinetics between 1 and 3,5-DTBC
was studied by observing the time dependent change in
35 absorbance at a wavelength of 401 nm, which is characteristic of
3,5-DTBQ in DCM. The colour of the solution gradually turned
deep brown indicative of gradual conversion of 3,5-DTBC to 3,5-
DTBQ. The difference in absorbance ΔA at 401 nm, was plotted
against time to obtain the initial rate for that particular catalyst to
40 substrate concentration ratio (Fig. 3). A first-order catalytic
reaction is observed, with initial rate 6.2 × 10-3 min-1. The
reaction follows a pseudo first order kinetics in oxygen-saturated
solvent medium.
Bond lengths
Co(1)-O(1)
Co(1)-O(2)
Co(1)-O(3)
Bond angles
1.856(2)
1.945(3)
1.875(2)
Co(1)-O(4)
Co(1)-N(1)
Co(1)-N(2)
1.952(3)
1.891(3)
1.887(3)
O(1)-Co(1)-O(2)
O(1)-Co(1)-O(3)
O(1)-Co(1)-O(4)
O(1)-Co(1)-N(1)
O(1)-Co(1)-N(2)
O(2)-Co(1)-O(3)
O(2)-Co(1)-O(4)
O(2)-Co(1)-N(1)
178.46(11)
O(2)-Co(1)-N(2)
90.07(11)
177.08(11)
89.47(11)
95.12(10)
90.93(12)
173.33(13)
84.25(11)
91.56(11)
91.28(12)
95.11(14)
89.62(10)
89.97(10)
87.18(12)
85.08(14)
O(3)-Co(1)-O(4)
O(3)-Co(1)-N(1)
O(3)-Co(1)-N(2)
N(1)-Co(1)-O(4)
N(1)-Co(1)-N(2)
N(2)-Co(1)-O(4)
45
50
55
Catecholase activity of 1: Spectrophotometric study
In order to study the catecholase activity of the complex 1; 3,5-
DTBC with two bulky t-butyl substituents on the ring and low
quinone-catechol reduction potential has been chosen as
substrate. This makes it easily oxidized to the corresponding o-
quinone, 3,5-DTBQ which is highly stable and shows a
maximum absorption at 401 nm in DCM. Solution of 1 was
5
10 treated with 100 equivalents of 3,5-DTBC under aerobic
conditions. The repetitive UV-Vis spectral scan was recorded in
pure DCM (Fig. 2). Spectral bands at 751, 495, 390 and 252 nm
appeared in the electronic spectrum of complex 1, whereas 3,5-
DTBC showed a single band at 282 nm. After addition of 3,5-
15
Fig. 3 A plot of the difference in absorbance (ΔA) vs time to evaluate the
initial rate of the catalytic oxidation of 3,5-DTBC by 1 in DCM.
The catecholase activity of complex 1 was similarly studied in
60 MeOH and MeCN media. In MeOH and MeCN also, 3,5-DTBQ
shows maximum absorption at 401 nm (Fig. 4 and Fig. 5). 3,5-
DTBQ obtained in each medium was purified by column
chromatography with yields 67.8% in MeOH and 76.5% in
MeCN. This was characterized by determining its melting point
65 (~110°C) which agreed well with that reported in literature.18 The
reaction kinetics was studied by observing the time dependent
change in absorbance at a wavelength of 401 nm for catalysis in
MeOH as well as in MeCN. The difference in absorbance ΔA at
this particular wavelength, were plotted against time to obtain the
20
Fig. 2 Change in spectral pattern of complex 1 in DCM after reaction with
3,5-DTBC, observing the reaction for 4 h.
DTBC, the time dependent spectral scan showed very smooth
growing of quinone band at 401 nm, as reported by Krebs et al,17
25 which indicated the formation of the respective quinone
derivative, 3,5-DTBQ which was purified by column
chromatography. The product was isolated in high yield (71.1 %)
by slow evaporation of the eluant and was identified by H1 NMR
spectroscopy (Fig. S2; Supporting Information). H1 NMR
30 (CDCl3, 400 MHz): δH = 1.16 (s, 9H), 1.20 (s, 9H), 6.15 (d, J =
2.4 Hz, 1H), 6.86 (d, J = 2.4 Hz, 1H).
70 Fig. 4 Change in spectral pattern of complex 1 after reaction with 3,5-
In order to find out the comparative reaction velocity between
DTBC, observing the reaction for 6 h in MeOH.
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 | 3

View Article Online
DOI: 10.1039/C4NJ01587H
Page 5 of 6
New Journal of Chemistry
initial rate of the reaction. A first-order catalytic reaction is 35 catechol and the cobalt complex is formed. In order to obtain a
observed in both the solvents, where the initial rates are found to
be 8.98 × 10-4 min-1 and 1.09 × 10-3 min-1 respectively in MeOH
and MeCN (Fig. S3 and Fig. S4; Supporting Information).
mechanistic inference of the catecholase activity and to get an
idea about the complex-substrate intermediate, we recorded an
ESI-MS spectrum (Fig. S8; Supporting information) of a 1:100
40
45
50
55
5 Fig. 5 Change in spectral pattern of complex 1 in MeCN after reaction
with 3,5-DTBC, observing the reaction for 6 h.
Fig. 6 Plot of rate vs. [substrate] in presence of 1 in DCM; inset:
Lineweaver-Burk plot.
Enzyme kinetics study
Enzymatic kinetic experiments were performed UV-Vis
spectrophotometrically thermostated at 25°C with complex 1 and
10 the substrate 3,5-DTBC in DCM, MeOH and MeCN. 0.04 ml of
the complex solution, with a constant concentration of 1 × 10-4
M, was added to 2 ml of 3,5-DTBC of a particular concentration
(varying its concentration from 1 × 10-3 M to 1 × 10-2 M) to
achieve the ultimate concentration of the complex as 1 × 10-4 M.
15 The conversion of 3,-5-DTBC to 3,5-DTBQ was monitored with
time at a wavelength of 401 nm for solutions in DCM, MeOH
and MeCN. The rate for each concentration of the substrate was
determined by the initial rate method.
The rate versus concentration of substrate data were analyzed
20 on the basis of Michaelis-Menten approach of enzymatic kinetics
to get the Lineweaver-Burk (double reciprocal) plot as well as the
values of the various kinetic parameters Vmax, KM and Kcat. The
observed rate vs. [substrate] plot in DCM solution as well as
Lineweaver-Burk plot is given in Fig. 6.
60 mixture of complex 1 and 3,5-DTBC of mixing them together.
The signal at m/z = 196 is due to the formation of the protonated
ligand [(L2)H]+. 3,5-DTBC can be indicated by the peak at m/z =
221. The peak at m/z = 243 can be assigned to sodium aggregate
of quinone [3,5-DTBQ-Na]+. The aqueous complex
65 [Co(L)2(H2O)]+ exhibits a peak at m/z = 463. Formation of a
sodium aggregate of the species 1a (Scheme 1) is identified by
the peak at m/z = 354. The intermediate Co(III) complex is
reduced to Co(II) by the catechol derivative and 3,5-DTBC itself
gets oxidised to quinone in presence of oxygen. The oxygen that
70 takes part in this process is converted to H2O2. H2O2 thus
liberated was identified and characterized spectrophotometrically
(S1; Supporting information).19
25
Similar plots in MeOH and MeCN are given in Fig. S5 and
Fig. S6; Supporting Information. The kinetic parameters are listed
in Table 3. The turnover numbers (Kcat) are 1.46 × 103, 1.21 × 103
and 2.16 × 103 h-1 in DCM, MeOH and MeCN, respectively.
75
Table 3 Kinetic parameters for the oxidation of 3,5-DTBC catalyzed by 1.
Solvent
Vmax (M s-1)
Std. error
KM (M)
Std. error
Kcat (h-1)
DCM
4.06 × 10-5
3.36 × 10-5
5.99 × 10-5
5.71 × 10-6
3.39 × 10-6
1.98 × 10-5
1.25 × 10-3
7.38 × 10-4
4.90 × 10-3
2.29 × 10-4
5.97 × 10-5
2.36 × 10-3
1.46 × 103
1.21 × 103
2.16 × 103
MeOH
MeCN
1a (Scheme 1)
30 Reaction Mechanism
The catalytic process follows a two-step mechanistic pathway.
This is evident from the rate plot (Fig. S7; Supporting
information). The first step, with a lesser rate constant value, is
the rate determining step. Probably, in this step, the 1:1 adduct of
Conclusions
80 In conclusion, we have synthesized and structurally characterized
one monometallic cobalt(III) complex (1) with an (N,O) donor
4
| Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

View Article Online
New Journal of Chemistry
DOI: 10.1039/C4NJ01P58a7gHe 6 of 6
60 5 (a) P. Comba, B. Martin, A. Muruganantham and J. Straub, Inorg.
Schiff base ligand. The catalytic property of 1 has been
kinetically investigated for the aerobic oxidation of 3,5-DTBC to
3,5-DTBQ in DCM, MeOH and MeCN which reveals that the
catalytic reaction follows first order reaction pathway. The
turnover numbers of 1 are 1.46 × 103, 1.21 × 103 and 2.16 × 103 h-
Chem., 2012, 51, 9214; (b) A. Neves, L. M. Rossi, A. J. Bortoluzzi,
B. Szpoganicz, C. Wiezbicki and E. Schwingel, Inorg. Chem., 2002,
41, 1788; (c) S. Torelli, C. Belle, I. Gautier-Luneau, J. L. Pierre, E.
Saint-Aman, J. M. Latour, L. L. Pape and D. Luneau, Inorg. Chem.,
2000, 39, 3526; (d) S. -C. Cheng and H. -H. Wei, Inorg. Chim. Acta,
2002, 340, 105.
(a) A. L. Abuhijleh, J. Pollitte and C. Woods, Inorg. Chim. Acta,
1994, 215, 131; (b) A. L. Abuhijleh, C. Woods, E. Bogas and G. L.
Guenniou, Inorg. Chim. Acta, 1992, 195, 67; (c) M. R. Malachowski,
M. G. Davidson and J. N. Hoffman, Inorg. Chim. Acta, 1989, 157,
91; (d) M. R. Malachowski and M. G. Davidson, Inorg. Chim. Acta,
1989, 162, 199; (e) M. Mitra, A. K. Maji, B. K. Ghosh, G. Kaur, A.
Roy Choudhury, C. -H. Lin, J. Ribas and R. Ghosh, Polyhedron,
2013, 61, 15.
5
65
70
1
in DCM, MeOH and MeCN, respectively which are much
6
greater than those reported in recent times. In a recent report by
Mohanta et al, the turnover numbers are 39 h-1, 40 h-1, and 48 h-1
in DMF, and 167 h-1 and 215 h-1 in MeCN for Cu(II)
10 complexes.4b The same group reported a mixed valence Co(III/II)
complex with turnover numbers 482.16 h−1 and 45.38 h−1 in
MeCN and MeOH, respectively.11 Rajak et al reported two Cu(II)
complexes which show a turnover rate of about 29 and 37 h-1.4e
A turnover rate of 28 h-1 of a Cu(II) complex is reported by
15 Neves et al.5b Ghosh et al reported three Ni(II) complexes with
turnover numbers 64.1, 51.1 and 81.7 h-1 in MeCN,8 and three
heterometallic Ni(II)-Mn(II) complexes with their turnover rates
ranging from 25.8 to 104.5 h–1.9 This indicates that 1 is a better
and effective model for catecholase activity than the recent
20 reported ones, though, to the best of our knowledge, the most
active catalyst4a reported so far, exhibits a turnover number of
3.24 × 104 h-1. So comparing all these data it can be concluded
that the reported complex (1) is quite an efficient catalyst and has
an appreciable turnover rates in various solvents. Besides, 1 being
25 a mononuclear complex with non-copper centre is mimicking an
enzyme with a dicopper active site.
75 7 (a) P. Kar, R. Haldar, C. J. Gómez-García and A. Ghosh, Inorg.
Chem., 2012, 51, 4265; (b) S. Mukherjee, T. Weyhermüller, E.
Bothe, K. Wieghardt and P. Chaudhuri, Dalton Trans., 2004, 3842;
(c) K. S. Banu, T. Chattopadhyay, A. Banerjee, M. Mukherjee, S.
Bhattacharya, G. K. Patra, E. Zangrando and D. Das, Dalton Trans.,
80
2009, 8755.
8
9
A. Biswas, L. K. Das, M. G. B. Drew, G. Aromí, P. Gamez and A.
Ghosh, Inorg. Chem., 2012, 51, 7993.
P. Seth, L. K. Das, M. G. B. Drew and A. Ghosh, Eur. J. Inorg.
Chem., 2012, 2232.
85 10 (a) L. I. Simándi, T. M. Simándi, Z. May and G. Besenyei, Coord.
Chem. Rev., 2003, 245, 85; (b) T. Megyes, Z. May, G. Schubert, T.
Grósz, L. I. Simándi and T. Radnai, Inorg. Chim. Acta, 2006, 359,
2329; (c) Z. May, L. I. Simándi and A. J. Vértes, Mol. Cat., 2007,
266, 239; (d) S. -I. Lo, J. -W. Lu, W. -J. Chen, S. -R. Wang, H. -H.
90
Wei and M. Katada, Inorg. Chim. Acta, 2009, 362, 4699; (e) M.
Mitra, A. K. Maji, B. K. Ghosh, P. Raghavaiah, J. Ribas and R.
Ghosh, Polyhedron, 2014, 67, 19.
Acknowledgement
11 S. Majumder, S. Mondal, P. Lemonie and S. S. Mohanta, Dalton
Trans., 2013, 42, 4561.
Financial support by the Department of Science & Technology,
New Delhi, India (F. No. SR/FT/CS-83/2010 dt. 11-02-2011) is
30 gratefully acknowledged by RG. Generous help in magnetic data
collection and mass spectrometric analysis respectively by Prof.
T. Mallah, Universitꢀ Paris Sud, France and Prof. M. Ali,
Jadavpur University, India are also acknowledged. MM is
thankful to The University of Burdwan for her research
35 fellowship.
95 12 A. Guha, T. Chattopadhyay, N. D. Paul, M. Mukherjee, S. Goswami,
T. K. Mondal, E. Zangrando and D. Das, Inorg. Chem., 2012, 51,
8750.
13 S. Yamada, Y. Kuge and K. Yamanouchi, Bull. Chem. Soc. Japan,
1970, 43, 406.
100 14 (a) S. Hazra, R. Koner, P. Lemoine, E. Carolina Sañudo and S.
Mohanta, Eur J. Inorg. Chem., 2009, 3458; (b) R. Koner, S. Hazra,
M. Fleck, A. Jana, C. R. Lucas and S. Mohanta, Eur J. Inorg. Chem.,
2009, 4982.
15 G. M. Sheldrick, Acta Cryst., 2008, A64, 112.
105 16 L. J. Farrugia, 1998, ORTEP-32 for Windows. University of
Glasgow, Scotland.
Notes and references
17 F. Zippel, F. Ahlers, R. Werner, W. Haase, H. -F. Nolting and B.
Krebs, Inorg. Chem., 1996, 35, 3409.
1
T. Klabunde, C. Eicken, J. C. Sacchettini and B. Krebs, Nat. Struct.
Biol., 1998, 5, 1084.
18 S. Tsuruya, S. -I. Yanai and M. Masai, Inorg. Chem., 1986, 25, 141.
110 19 (a) A. I. Vogel, Textbook of quantitative inorganic analysis, 3rd ed.,
Longmans, Green and Co. Ltd., London, 1961, 366; (b) A. Neves, L.
M. Rossi, A. J. Bortoluzzi, B. Szpoganicz, C. Wiezbicki and E.
Schwingel, Inorg. Chem., 2002, 41, 1788; (c) E. Monzani, L. Quinti,
A. Perotti, L. Casella, M. Gullotti, L. Randaccio, S. Geremia, G.
40 2 (a) M. Merkel, N. Möller, M. Piacenza, S. Grimme, A. Rompel and
B. Krebs, Chem. Eur. J., 2005, 11, 1201; (b) J. Reim and B. Krebs, J.
Chem. Soc., Dalton Trans., 1997, 3793; (c) B. Sreenivasulu, F. Zhao,
S. Gao and J. J. Vittal, Eur. J. Inorg. Chem., 2006, 2656; (d) C. -T.
Yang, M. Vetrichelvan, M. Yang, B. Moubaraki, K. S. Murrey and J.
115
Nardin, P. Faleschini and G. Tabbi, Inorg.Chem., 1998, 37, 553.
45
50
55
J. Vittal, Dalton Trans., 2004, 113.
3
(a) I. A. Koval, P. Gamez, C. Belle, K. Selmeczi and J. Reedijk,
Chem. Soc. Rev., 2006, 35, 814; (b) I. A. Koval, K. Selmeczi, C.
Belle, C. Philouze, E. Saint-Aman, I. Gautier-Luneau, A. M.
Schuitema, M. van Vliet, P. Gamez, O. Roubeau, M. Lüken, B.
Krebs, M. Lutz, A. L. Spek, J. -L. Pierre and J. Reedijk, Chem. Eur.
J., 2006, 12, 6138.
4
(a) K. S. Banu, T. Chattopadhyay, A. Banerjee, S. Bhattacharya, E.
Suresh, M. Nethaji, E. Zangrando and D. Das, Inorg. Chem., 2008,
47, 7083; (b) S. Majumder, S. Sarkar, S. Sasmal, E. Carolina Sãnudo
and S. S. Mohanta, Inorg. Chem., 2011, 50, 7540; (c) A. Biswas, L.
K. Das, M. G. B. Drew, C. Diaz and A. Ghosh, Inorg. Chem., 2012,
51, 10111; (d) S. Mandal, J. Mukherjee, F. Lloret and R. Mukherjee,
Inorg. Chem., 2012, 51, 13148; (e) A. Banerjee, S. Sarkar, D.
Chopra, E. Colacio and K. K. Rajak, Inorg. Chem., 2008, 47, 4023.
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 | 5