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CHAPTER I
CHAPTER I
INTRODUCTION
CHAPTER I
1
1.1.INTRODUCTION
The first complexes to be the subject of any great study were the cobalt
ammines. As early as 1798 Tassaert observed that a solution of a cobalt(II) salt in
aqueous ammonia becomes brown on exposure to air, the colour changing to wine red
on boiling. Some decades later, Fremy showed that the cobalt had been oxidized to
cobalt(III) and that the new salt is associated with up to six ammonia molecules, for
e.g., CoCl3.6NH3. This compound stimulated interest because it was difficult to
understand how the two compounds CoCl3 and NH3 each with its valency satisfied,
could combined together to form a stable compound. Many more complexes of
ammonia were prepared subsequently. The reactions of nickel chloride and copper
sulphate solutions with an excess of ammonia were found to give deeply coloured
solutions from which the purple NiCl2.6NH3 and the deep blue CuSO4.4NH3.H2O
could be isolated. However, it was with cobalt(III) and platinum(II) that a wide
variety of ammonia complexes (ammines) could be prepared, and it was the study of
the properties of these series of ammines that was to shed much light on the structures
of coordination compounds.
While their structures were unknown, these new compounds were often named
according to their colour. Thus the orange-yellow CoCl3.6NH3 was called
luteocobaltic chloride, the purple CoCl3.5NH3 purpureocobaltic chloride and the
green isomer of CoCl3.4NH3 praseocobaltic chloride. Other complexes were named
after their discoverers, for e.g. Magnus green salt PtCl2.2NH3 (now formulated as
[Pt(NH3)4)][PtCl4]) and Reinecks‟s salt Cr(SCN)3.NH4SCN.2NH3 (now formulated as
NH4[Cr(NH3)2(NCS4)]. Around 1830 Zeise found that ethylene could form
compounds with platinum salts, and he was able to isolate complexes of formulae
PtCl2.C2H4
and PtCl2.KCl.C2H4. These compounds were first organometallic
compounds of the transition elements to be prepared; their structures have been
elucidated only fairly recently and the potassium compound (now formulated as
K[PtCl3(C2H4)]) is still often called Zeise‟s salt.
Coordination chemistry has an old history originating in the discovery of
[Co(NH3)6]Cl3 by Tassaert in 1798 [1]. But it was Werner who systematized the
subject by propounding his coordination theory in 1893 [2]. Werner‟s basic ideas on
the stereochemistry of metal complexes, mechanisms of isomerization and
CHAPTER I
2
racemization, etc. remain unchallenged even today despite all the monumental
developments which have taken places since his days and during the last five decades
in particular, owing to the advent of sophisticated physico-chemical techniques of
high precision and capability [3, 4]. These have considerably enriched our
understanding of the nature of the metal-ligand bond, structure and stereochemistry of
metal complexes, their stabilities and liabilities and other properties. Even metals
which were earlier thought to be non-complex formers are now known to form quite
stable complexes with special types of ligands, such as the alkali metal complexes
formed by crown ethers and cryptates [5-8].
The growth of coordination chemistry has been three dimensional,
encompassing breadth, depth, and applications. The ongoing respect for the evolving
science is apparent in the five Noble prizes that have been impinged heavily on the
subject (A. Werner, 1913; M. Eigen, 1967; Wilkinson & Fischer, 1973; H. Taube,
1983; Cram, Lehn and Pedersen 1987). The first (Werner) and last (Cram, Lehn &
Pedersen) in the list recognized the old and the new realms of coordination chemistry
specifically [9].
In the real sense, coordination chemistry is an area that has many fields, like
transition metal chemistry, organo-metallic chemistry, homogeneous catalysis,
bioinorganic chemistry, medicinal chemistry etc. an equally important, it is a
foundational to other growing fields for e.g. Solid-state chemistry, extended and
mesoscopic materials, photonic materials, model for solid surfaces, separation
science, molecular electronics, machines and devices. The enormous extensions of the
field reflect its fundamental nature; the principles are so basic that they have
immediate applications as some undreamt of new substances serendipitously appear in
chemistry (e.g., dihydrogen complexes, metal derivatives of fullerenes, metal
containing liquid crystals). The spawning of new fields is an inevitable consequence
of the foundational position of coordination chemistry in the chemical sciences.
The chemistry of coordination compounds with heterocyclic ligands
containing oxygen and nitrogen as donor atoms has attracted increasing attention in
recent years. It is well known that such ligands coordinate to a metal atom in different
ways in different media. Transition metal ions are essential in many biological
systems in nature [10]. These metal complexes with bidentate and tetradentate ligands
CHAPTER I
3
containing both hard and soft donor groups have been used extensively in
coordination and organometallic chemistry [11]. The chelating properties of Schiff
bases display manifold applications in medicine, industry, and agriculture [12]. The
transition metal complexes of Schiff bases have exhibited fungicidal and bactericidal
activities including regulating the growth of plants [13]. It is known that chelation of
metal ions with organic ligands acts synergistically to increase its effect [14]. The
coordination chemistry of the square planar palladium(II) and platinum(II) complexes
of nitrogen and sulfur/oxygen donor ligands have gained enormous importance
because of their antitumour [15], anticancer [16], and catalytic activities [17].
Antimicrobial aspects [18] and antifertility activity [19] of coordination compounds of
palladium (II) and platinum (II) have also been reported in recent years.
Coordination compounds exhibit different characteristic properties, which
depend on the metal ion to which ligands are bound, the nature of the metal, as well as
the type of ligand. These metal complexes have found extensive applications in
various fields such as biology, medicine etc. The nature of a coordination compound
depends on the metal ion and the donor atoms, as well as on the structure of the ligand
and the metal–ligand interaction [20]. With increasing knowledge of the properties of
functional groups, as well as the nature of donor atoms and the central metal ion,
ligands with more selective chelating groups, i.e., imines or azomethines which are
more commonly known as Schiff bases are used for complex formation studies. It is
reported that the rapidly developing field of bioinorganic chemistry is centered on the
presence of coordination compounds in living systems [21].
One of the most important problem in coordination chemistry has been the
nature and strength of metal-ligand bond. Normally the metal ion does not form bonds
of equal strength with two different donor atoms. Similarly, a particular donor atom
does not form bonds of the same strength with different metal ions [22].
Donor Atoms
Fundamentally any part of molecule that happens to be more basic than the C-
H portions is potential electron donors. Amino acids, peptides, proteins, hormones,
nucleoproteins, nucleic acids, carboxylic acids, carbohydrates, lipids, simple anions
and even the solvent water contain some electron donor elements such as nitrogen,
oxygen, fluorine, phosphorous, sulphur, chlorine, bromine and iodine. Quite recently
CHAPTER I
4
even carbon has been shown to form bonds to metal ion [23]. The common electron
donor groups employed in drugs are indicated in below Figure. The actual donor
groups selected by the metal depend upon many factors that are conveniently
discussed using the “hard and soft acids and bases” theory.
Common electron donor groups
Schiff Base and Metal Complexes
With ever increasing knowledge of properties of functional groups and nature
of donor atoms and the central metal ion, ligands with more selective chelating group
called anils, imines and azomethines or best known as Schiff bases are being used for
the complex formation studies. They have general structure RC=NR‟ where R and R‟
are alkyl, aryl or heterocyclic compounds. Extensive investigation in the field of
Schiff bases have been reported by Bayer [24]. Their preparation, chemical and
physical properties have been described by Layer [25], Dwyer and Mellor [26]. It
concern primarily with the stereochemistry of Schiff base complexes as well as aspect
of behavior of such complexes in solution, has also been published [27].
Schiff bases have recently gained much interest due to their delocalized π-
orbitals, flexible behaviour, multifunctional ligating sites etc., Also the Schiff base
complexes have great biological importance especially in the field of model
compounds studies. They impart to the catalyst a good tolerance towards organic
functionalities, air and moisture, in this way widening the area of application.
Schiff base ligands have played an important role in the development of
coordination chemistry since the late nineteenth century. The finding that metal
CHAPTER I
5
complexes of these ligands are ubiquitous is a reflection of their facile synthesis, wide
application and accessibility of diverse structural modifications [28]. Schiff base
metal complexes have been known since the mid nineteenth century [29] and even
before the general preparation of the Schiff base ligands themselves. Schiff base metal
complexes have occupied a central place in the development of coordination
chemistry after the work of Jorgensen and Werner [30]. However, there was no
comprehensive, systematic study until the preparative work of Pfeiffer and associates
[31]. Pfeiffer et al., [32] reported a series of complexes derived from Schiff bases of
salicylaldehyde and its substituted analogues. In the past two decades, the properties
of Schiff base metal complexes stimulated much interest for their contributions to
single molecule-based magnetism, material science, catalysis of many reactions like
carbonylation, hydroformylation, oxidation, reduction and epoxidation, their
industrial applications and complexing ability towards some toxic metals. The high
affinity for the chelation of the Schiff bases towards the transition metal ions is
utilized in preparing their solid complexes [33]. Schiff base complexes containing
nitrogen and oxygen as donor atoms play an important role in biological systems and
represent models for metalloproteins and metalloenzymes that catalyze the reduction
of nitrogen and oxygen [34].
In recent years, it has been the trend to synthesize the ligand molecule having
definite frame work of donor atoms and to stitch them to different metal ions. Among
the coordination compounds, those derived from Schiff bases are of particular
interest. Schiff base ligands have been in the chemistry literature for over 150 years.
The literature survey clearly reveals that the study of this diverse ligand system is
linked with many of the key advances made in the field of inorganic chemistry.
Schiff base ligands are a class of polyatomic systems containing one or more
C=N bond, with at least one aryl group attached to either C or N. The ligands are
generally accessible by easy methods and the synthesis of these ligands was first
reported by Schiff [35]. The most common method of obtaining Schiff base [35] is
straight forward as indicated in the condensation reaction between a primary amine
with aldehyde or ketone.
CHAPTER I
6
Other methods of synthesis of Schiff bases are widely reviewed by Dayagi and
Degani [36]. Schiff bases can be characterized by IR, NMR, UV-Vis and mass
spectral methods. The C=N stretching frequencies of the ligands generally occur in
the region 1680 and 1603 cm-1
when H, alkyl or aromatic groups are bound to C and
N atoms. The natures of different substituents on these atoms determine the position
of the stretching frequencies in the above range. For e.g., aryl groups on C and N
atoms cause a shift of the frequency towards the lower side of the range. A summary
of typical IR frequencies for various Schiff base ligands are available in the literature
[37]. NMR spectroscopy is very useful in understanding structural features of ligands
in solution, in particular keto-enol tautomerism found in these ligands (2, 3).
Schiff bases have exhibited higher coordination number and from kinetics and
thermodynamic point of view, they are important class of compounds, resulting in an
enormous number of publications and literature review, ranging from pure synthetic
work to physico-chemical and biochemically relevant studies of metal complexes and
found wide range of applications.
Schiff bases are generally bidentate, tridentate, tetradentate or polydentate
ligands capable of forming very stable complexes with transition metals. They can
only act as coordinating ligands if they bear a functional group, usually the hydroxyl,
sufficiently near the site of condensation in such a way that a five or six membered
ring can be formed when reacting with a metal ion. Schiff bases derived from
aromatic amines and aromatic aldehydes have a wide variety of applications in many
fields, e.g., biological, inorganic and analytical chemistry [38, 39]. Schiff bases are
used in optical and electrochemical sensors, as well as in various chromatographic
methods, to enable detection of enhanced selectivity and sensitivity [40-42]. Among
the organic reagents actually used, Schiff bases possess excellent characteristics,
structural similarities with natural biological substances, relatively simple preparation
procedures and the synthetic flexibility that enables design of suitable structural
properties [43, 44]. Schiff bases are also effective corrosion inhibitors and could be
adsorbed on the surface of metals [45].
CHAPTER I
7
Schiff bases offer opportunities for inducing substrate chirality, tuning the
metal centered electronic factor, enhancing solubility, either performing homogenous
or heterogeneous catalyses, include diversified subjects comprising their various
aspects in bio-coordination and bio-inorganic chemistry. Schiff bases are widely
applicable in analytical determination, using reactions of condensation of primary
amines and carbonyl compounds in which the azomethine bond is formed
(determination of compounds with an amino or carbonyl group) using complex
formation reactions (determination of amines, carbonyl compounds and metal ions) or
utilizing the variation in their spectroscopic characteristics following changes in pH
and solvent [46]. Schiff bases are widely studied in coordination chemistry as they
easily form stable complexes with most transition metal ions [47, 48]. Many
biologically important Schiff bases have been reported in the literature possessing,
antimicrobial, anticonvulsant, antitumor and anti HIV activities [49-54] which may be
due to the presence of azomethine linkage [55-57]. The applications of Schiff bases
and their importance in the field of coordination chemistry have generated a great deal
of interest in the synthesis of new metal complexes.
Schiff base transition metal complexes are one of the most adaptable and
thoroughly studies systems [58, 59]. They are of both stereochemical and
magnetochemical interest due to their preparative accessibility, diversity and
structural variability [60]. Metal complexes play an essential role in agriculture,
pharmaceutical and industrial chemistry [61]. Heteronuclear Schiff base complexes
have found applications as magnetic materials, catalysts and in the field of bio-
engineering [62, 63].
Transition metal complexes have attracted attentions of inorganic, metallo-
organic as well as bio-inorganic chemists because of their extensive applications in
wide ranging areas from materials to biological sciences [64]. It is well known that N
and S atoms play a key role in the coordination of metals at the active sites of
numerous metallobiomolecules [65]. Schiff base metal complexes have been widely
studied because they serve as models for biologically important species and find
applications in biomimetic catalytic reactions. Chelating ligands containing N, S and
O donor atoms show broad spectrum of biological activity and are of special interest
because of the variety of ways in which they are bonded to metal ions. It is known
that the existence of metal ions bonded to biologically active compounds may
CHAPTER I
8
enhance their activities [66, 67]. Transition metal complexes have emerged as
potential building blocks for nonlinear optical materials due to the various excited
states present in these systems as well as due to their ability to tailor metal-organic-
ligand interactions [68-70]. Inorganic complexes can be used in foot printing studies,
as sequence specific DNA binding agents, as diagnostic agents in medicinal
applications, and for genomic research.
Transition metal complexes derived from Schiff bases have occupied a central
role in the development of coordination chemistry. The azomethine group > C=N of
the Schiff base forming a stable metal complexes by coordinating through nitrogen
atom. Large number of Schiff bases has been investigated by many workers as
chelating agents. Most of them are prepared by the condensation of salicyldehyde
with aromatic amines and aliphatic amines. Calvin and Berkelow [71] have
synthesized nearly twelve anils by condensing salicyldehyde with substituted anilines
and other aromatic amines.
Azomethines and their complexing capabilities have been enlightened in many
review articles [72-75]. Hydrazones are the special group of compounds of Schiff
bases. They are characterized by the presence of >C=N-N< group. The presence of
two inter-linked nitrogen atoms separates from imines, oximes, etc. Many hydrazones
and their metal complexes have biological and pharmaceutical activities such as
anticancer, antitumor and antioxidative activities as well as inhibition of lipid
peroxidation etc. [76-78]. Many drugs may possess modified toxicological and
pharmacological properties when administered in the form of complexes. The most
widely studied metal in this respect is Copper(II), which proved to be beneficial in
diseases such as tuberculosis, gastric ulcers and rheumatoid arthritis [79, 80].
Hydrazides represent a very interesting class of compounds because of their
wide applications in pharmaceutical, analytical and industrial aspects, e.g., as
antibacterial, antifungal, anti-inflammatory, antitubercular, anti-HIV, anti-
degenerative activities and herbicides [81-86]. Numerous hydrazide derivatives of
Schiff base ligands and their transition metal complexes have been investigated by
various physico-chemical techniques [87-90].
The basic strength of C=N group is not sufficient to obtain stable complexes
by coordination of the imino nitrogen atom to the metal ion. Hence, the presence of at
CHAPTER I
9
least one other group is required to stabilize metal-nitrogen bond [91]. This is evident
from the literature review that synthesis of different types of potential Schiff bases on
the basis of their donor atoms set has been attempted. Based on the donating sites,
further Schiff bases are classified as monodentate, bidentate, tridentate, tetradentate
and polydentate ligands containing O, N and S donor atoms. Such type of donor site
ligands have been tried for their complexation and the structures were deduced with
the aid of analytical, physico-chemical and spectral data.
In this introductory section of the thesis, a brief review of Schiff base ligands
will be presented using illustrative examples from some of the above mentioned
classes of ligands.
Monodentate Schiff bases
It has been claimed that the basic strength of C=N group is not sufficient to
obtain stable complexes by coordination of the azomethine nitrogen atom to a metal
ion [91]. Hence the presence of at least one other group is required to stabilize metal-
nitrogen bond. Aryl groups attached to either O or N generally stabilize the ligands by
resonance. For e.g. monoamine Schiff bases such as N-(o-
hydroxybenzaldehydo)aniline BAAN derivatives (4) are well known in the literature
[37].
The ligand (4) variously substituted in the phenyl rings, has been the most
extensively studied ligand by NMR and X-ray analysis. 1H and
13C NMR spectra of
some BAAN derivatives have been reported. The azomethine proton was observed in
the region 8.41-8.5 ppm. These ligands exhibit solution spectral properties different
from their corresponding isoelectronic trans-azobenzene and trans-stilbene. These
differences are attributed to the non-planar structure of N-(o-
hydroxybenzaldehydo)aniline BAAN derivatives in solution. Since the spectral
properties are sensitive function of the molecular conformation, systematic studies on
the solid state structure have been carried out. Furthermore, since the original work of
Burgi and Dunitz [92], many workers have thought of utilizing the BAAN derivatives
CHAPTER I
10
in crystal engineering because of their thermochromism and photochromism
properties. The geometrical parameters defining the overall conformation of these
Schiff bases and the geometry of C=N moiety have been described in the literature.
On the other hand, it has been reported recently [93] that the Schiff base
(5 and 5a) being monodentate in nature, is able to act as a ligand in the Pd complex,
because of the suggested interaction Pd---H, which may stabilize the coordination of
the ligand to the metal.
Bidendate Schiff bases
Bidentate Schiff bases have been amongst the widely used ligands in
preparing metal complexes. A brief review of potential bidentate ligands according to
their donor atom set is described in the following subsections.
N, N donor atom set
Schiff bases having two nitrogen atom donors may be derived either from the
condensation of dialdehydes or diketones with two molecules of an amine or from
reaction of diamines with aldehydes or ketones. The typical example may be
bis(benzylidene)-1,2-diphenylethylenediamine (6). The structure and coordination
behaviour of these ligands have been extensively studied [94].
Another ligand is derived from 2-pyrrolecarboxaldehyde and ammonia acts as
a monoanionic ligands and forms a complex (7) with copper(II) ion.
CHAPTER I
11
Recently, a series of condensation products of the ketoximes (8) with amines
have been prepared and the species formed were investigated by X-ray, NMR and IR
studies [95].
N, O donor atom set
A large group of bidentate Schiff bases having N, O donor atom set have been
utilized as ligands for metals, since oxygen is often present as an OH group, these
ligands generally act as chelating monoanions. But, it must be pointed out that
Sacconi et al., [96] have shown that the hydroxyl oxygen atoms under certain
circumstances may bridge two metal atoms. In this case the Schiff bases should be
considered as tridentate ligands which favour the formation of binuclear complexes.
Ekk Sinn [97]
has reported some Cu-complexes of N-(ethyl-2-
hydroxybenzylidenimine) (9) in which the hydroxyl oxygen is coordinated to two
copper atoms, the ligand as a whole behaved in a tridentate fashion bonding through
imine nitrogen and phenoxide bridging.
CHAPTER I
12
The copper(II) complexes of such ligands have shown dimeric structures and
these complexes have shown some antiferromagnetic exchange behaviour between
the two paramagnetic centres [96, 97].
On the other hand, there are few examples of coordinated neutral N, O
bidentate Schiff bases derived from -diketones and 2-hydroxy aldehydes. The most
studied bidentate Schiff bases containing N, O donor set are those derived from
substituted salicylaldehyde derivatives and amines (10). Large variety of transition
metal complexes of these ligands are known in the chemistry literature [98, 99].
Kandil et al., [100] have reported a new bidentate Schiff base ligand
containing heterocyclic moiety, 3-(2-furylidene)hydrazino-5,6-diphenyl-1,2,4-triazine
(11) and its copper(II) and cobalt(II) complexes. The ligand behaved in a bidentate
fashion coordinating through azomethine nitrogen and triazine nitrogen
Alaaddin et al., [101] have synthesized two new Schiff base ligands containing
cyclobutane and thiazole rings. 4-(1-methyl-1-mesitylcyclobutane-3-yl)-2-(2,4-
dihydroxy benzilidenehydrazino)thiazole (12) and 4-(1-methyl-1-mesitylcyclobutane-
3-yl)-2-(2-hydroxy-3-methoxybenzylidenehydrazine)thiazole (13) and their
mononuclear complexes of cobalt(II), copper(II), nickel(II) and zinc(II). The
complexes were characterized by microanalysis, IR, UV-visible, NMR and magnetic
susceptibility measurements.
CHAPTER I
13
Singh et al., [102] have synthesized 2-furoyl hydrazones of 2-acetyl thiophene
and 2-acetyl furan (14) and (15) and their Cu(II), Co(II), Ni(II), Zn(II) and Mn(II)
complexes. Later on they have also synthesized Fe(III) complexes with the same
ligand [103].
Aurora et al., [104] have synthesized N-(2-furanylmethylene)-3-
aminodibenzofuran (16) and their Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II)
complexes.
Spinu et al., [105] have synthesized N-(2-thienylmethylidene)-2-
aminopyridine (17) and their Fe(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)
complexes. The complexes have been characterized by elemental analysis, IR, 1H
NMR, electronic spectra and magnetic susceptibility measurements. These results
suggest a distorted octahedral geometry for the Fe(II), Co(II), Ni(II) and Cu(II)
complexes and a tetrahedral geometry for the Zn(II) and Cd(II) complexes.
The Co(II), Mn(II) and Zn(II) complexes of bidentate Schiff base (18) derived
from aniline and salicylaldehyde have been reported by Rehman [106] and others.
These complexes have been characterized by elemental analysis and spectral
techniques. The results obtained showed that the complexes have octahedral
geometry.
CHAPTER I
14
Cu(II) complexes of bidentate Schiff base 4-methoxy-2-(1H-benzimidazol-2-
yl)-phenol and its methyl / chloro / nitro derivatives (19) have been reported by
Tavman et al., [107].
Synthesis, physico-chemical investigations and biological studies on Mn(II),
Co(II), Ni(II), Cu(II) and Zn(II) complexes with p-amino acetophenone isonicotinoyl
hydrazone have been reported by Singh et al., [108]. The results obtained by spectral
and other physico-chemical techniques showed that the complexes have octahedral
geometry (20).
Recently, Mruthyunjayaswamy et al., [109] have synthesized 3-chloro-N'-(3-
methoxybenzylidene)benzo[b]thiophene-2-carbohydrazide (21) and their Cu(II),
Co(II), Ni(II), Zn(II), Cd(II) and Hg(II) complexes. The complexes have been
characterized by elemental analysis, IR, 1H NMR, electronic spectra and magnetic
susceptibility measurements. These results suggest all the complexes were octahedral
geometry with slight distortion in Cu(II) complex.
CHAPTER I
15
Tridentate Schiff bases
There are large number of tridentate Schiff bases containing N2O, N2S, NO2
and NSO donor sets [110]. These may be generally considered as derived from the
bidentate analogues by the addition of another donor group. It must be pointed out
that the oxygen donor atom of such ligands may often act as bridging between two
metal centres giving polynuclear complexes. Some typical tridentate ligands. (22, 23)
are given below.
The tridentate Schiff bases containing two active centres and a donor centre
form complexes with transition metals which are generally dimeric in nature.
Copper(II) and oxovanadium(IV) complexes with such ligands are some examples
reported in the literature [111]. The structures of such complexes have been proposed
on the basis of spectrochemical and magnetic susceptibility measurement studies. The
octahedral complexes with such type of tridentate ligands have been reported in the
literature [111].The neutral tridentate ligands are shown to form octahedral complexes
with transition metals where two ligands encompass the metal ion in an octahedral
array [112, 113].
The Co(II), Ni(II), Cu(II) and Cd(II) complexes of tridentate Schiff base (24)
have been reported by Nawar et al., [114]. These complexes have been characterized
by elemental analysis, IR, 1H NMR, mass, electronic spectra and magnetic
susceptibility measurements, spectrophotometric and potentiometric studies.
CHAPTER I
16
Naik et al., [115] have reported the synthesis, spectroscopic and thermal
studies of Co(II), Ni(II) and Cu(II) complexes of the hydrazone (25) derived from 2-
benzimidazolyl mercaptoaceto hydrazide and o-hydroxy aromatic aldehydes.
The Co(II), Ni(II), Cu(II) and Cd(II) complexes of tridentate Schiff base, 4-[2-
(aminomethyl)pyridylisonitroacetyl)diphenylether (26) have been reported by Coskun
and Yilmaz [116].
Gudasi et al., [117, 118] have reported Co(II), Ni(II), Cu(II), Zn(II), Cd(II),
Oxovanadium(IV) and Ln(III) complexes with 2-(3-coumarinyl)imidazole[1-2a]
pyridine (CIP), (27) which were found to possess good antifungal and antibacterial
activity.
Sanjay Annarao [119] have reported the synthesis of 3-acetyl coumarine
semicarbazone (28) and 3-acetyl coumarine thiosemicarbazone (29) and their Zn(II),
Cd(II) and Hg(II) complexes. Based on the elemental, spectral, magnetic and
solubility studies, the Co(II), Ni(II) and Cu(II) complexes are predicted to possess
octahedral geometry and Zn(II), Cd(II) and Hg(II) complexes tetrahedral geometry.
CHAPTER I
17
Bamfield et al., [120] and Chakravarty et al., [121] have reported penta
coordinated Fe(II), Co(II), Ni(II) and Zn(II) complexes containing tridentate ligands.
Monovalent tridentate ligands containing ONN, ONS and ONO donor sets have been
synthesized in recent years and metal complexes have been studied in detail. A simple
example of a Schiff base containing ONN sequence may be found in 2-
aldehydopyridine-o-aminophenol (30) [122].
Revankar et al., [123] have synthesized a series of Co(II), Ni(II), Cu(II) and
Zn(II) complexes of quinoline-thiosemicarbazone Schiff base (31) with ONS donor
atoms. The ligand and complexes were characterized by elemental analysis and
various spectral studies. Based on these studies, all the complexes have been assigned
octahedral geometry except the Cu(II) complexes which possess square pyramidal
structure. Further, the Schiff base has exhibited good antimicrobial activity and the
complexes have shown higher activity than the ligand.
Mruthyunjayaswamy et al., [124] have synthesized Co(II), Ni(II) and Cu(II)
complexes Schiff bases derived from 3-Phenyl-5-substituted indole-2-
carboxyhydrazones of salicylaldehyde (32).
CHAPTER I
18
The ligands and complexes were characterized by elemental analysis and
various spectroscopic techniques. The results reveled that all the complexes possess
octahedral geometry. The ligands and complexes were also screened for antimicrobial
activity against Staphylococcus aureus, Escherichia coli and Aspergillus niger
Singh et al., [125] have synthesized 2-furoylhydrazones of 2-acetylpyridine
(33) and their Cu(II), Ni(II), Co(II), Zn(II), Mn(II) and VO(IV) complexes, later they
have also synthesized Fe(II) complexes with the above said ligands [126].
Mruthyunjayaswamy et al., have synthesized three new Schiff base ligands 3-
(4-phenylthiozole-2-yl)-1-(2-hydroxy-1-iminomethylphenyl)urea (34) and 3-(4-
phenylthiozole-2-yl)-1-(2,4-dihydroxy/2-hydroxy-5-chloro-1-methylimino
methylphenyl)ureas (35a-b) and their Cu(II), Co(II) and Ni(II) complexes. The
complexes have been characterized by elemental analysis, conductance
measurements, magnetic susceptibility, electronic spectra, IR and TGA studies. The
studies reveal that the ligand has coordinated as tridentate chelating agent bonding
through o-hydroxy group, amide carbonyl function and azomethine nitrogen. All the
complexes have octahedral stereochemistry [127].
Recently, Vivekanad and Mruthyunjayaswamy [128, 129] have synthesized
Schiff bases 5-chloro-3-phenyl-N1-((2-thioxo-1,2,dihydroquinoline-3-yl)methylene)-
1H-indole-2-carbohydrazide (36) and 3-chloro-6-methoxy-N‟-((2-thioxo-1, 2-
dihydroquinolin-3-yl) methylene)benzo[b]thiophene-2-carboxyhydrazide (37) and
their metal complexes. These complexes were characterized by elemental analysis,
CHAPTER I
19
conductance measurements, magnetic susceptibility, electronic spectra, IR and TGA
studies.
Mruthyunjayaswamy et al., have synthesized [130] the Schiff base 5-chloro-
N-[(2‟-dihydro-2‟-oxoquinolin-3‟-yl methylene)-3-phenyl-1H-indole-2-
carbohydrazide (38) and its Cu(II), Co(II), Ni(II), Zn(II), Cd(II) and Hg(II)
complexes. The ligand and complexes were characterized by elemental analysis,
conductance measurements, magnetic susceptibility, electronic spectra, IR and TGA
studies. The results reveled that Schiff base acts as tridentate (ONO) chelating agent
coordinate with metal ions through the oxygen atom of carbonyl group of amide
function attached to 2-position of indole, azomethine nitrogen and oxygen atom of the
enolized amide function of qunilinone moiety via deprotonation. Analytical, spectral
and magnetic studies revealed mononuclear nature of the complexes. The Cu(II),
Co(II) and Ni(II) complexes exhibited octahedral geometry whereas Zn(II), Cd(II)
and Hg(II) complexes exhibited tetrahedral geometry. The synthesized ligand and its
complexes were screened for antimicrobial, antioxidant and DNA cleavage activity.
Tetradentate Schiff bases
Tetradentate Schiff bases with N2O2 donor set have been widely studied for
their ability to coordinate with metal ions. The properties of complexes obtained by
these ligands are determined by an electronic nature of the ligands as well as by their
conformational behavior [131].
CHAPTER I
20
Dubsky and Sokol [132] have reported the reactions of salicylaldehyde with
diamines. These display tetradentate behavior by forming square-planar complexes
(39) with Ni(II) and Cu(II).
Sacconi and Bertini [133] have reported Cu(II) complexes of quadridentate
ligands derived from ethylene diamine and acetyl acetone. Similarly Morgan and
Mainsmith [134] have reported a green complex (40).
X-ray analysis of the structure of Copper(II) chelates revealed that acac rings
are considerably conjugated with possible preponderance of the structure derived
from ketimine form of the ligand. The chelate molecule is expected to be planar but
for some puckering in the central chelate ring, it is slightly concave towards the centre
[135]. The cobalt(II) complexes (41) of such bases have also been reported [136].
Dubsky and Sokol [137] have prepared Schiff bases by reacting
salicylaldehyde with diamines. These display tetradentate behaviour by forming
square planar complexes with Ni(II) and Cu(II). It has been established that most of
the Ni(II) complexes with tetradentate Schiff bases are square planar and monomeric
in nature. In an extensive IR study of Ni(II) complexes, Gluvchinsky et al., [138] have
demonstrated that Schiff bases obtained from salicylaldehyde and diamines
H2N(CH2)nNH2, when n =2 and 3 form monomeric square planar complexes but when
n = 5 and 6 they form trimeric complexes with octahedral and square planar Ni(II)
moieties. The most interesting observation is due to Tanaka and Kono [139] who
observed the impact of lengthening of hydrocarbon chain between the two azomethine
groups on the colours of the copper(II) complexes of the above ligand . With change
CHAPTER I
21
in number from 2-6, the colour of the complex changed from yellowish green to pale
blue. Similar observations have also been made in the case of Co(II) and Ni(II)
complexes. It has been found that the lengthening of the hydrocarbon chain has a
profound impact on the geometry of Cobalt(II) complexes [140].
Zacharios et al., [141] have reported the reactions of salicylaldehyde with o-
phenylenediamine and studied the behavior of the resultant Schiff base in
complexation with Co(II), Ni(II) and Cu(II) metal ions . These display tetradentate
behavior by forming metal complexes (42) containing two six membered and one five
membered ring.
Henri et al., [142] have synthesized a tetradendate ligand (43) by reacting 2, 3-
diaminopyridine with o-vanillin and its Cu(II), Ni(II), Ru(II), Zn(II), and Fe(III)
complexes.
Dencinti et al., [143] have reported electrochemical properties of copper(II)
complexes with salen ligands (44). The Schiff base ligands studied gave cyclic the
voltammograms at 100 mVs-1
consists of a single cathodic peak potential ranging
from –1.6 to –2.0 V. No anodic wave occurred in the reverse scan. This behavior has
been observed for a wide range of scan rates from 25 to 100 mVs-1
. Hence such
reduction process should correspond to a totally irreversible electron transfer. The
cyclic voltammetric curves from the electrochemical reduction of the studied
CHAPTER I
22
copper(II) complexes exhibit a redox couple at potential in the range -0.91 to -1.28 V,
which can be attributed to the reduction of the metal center in the complex.
Some neutral tetradentate N2O2 type complexes of Co(II) have been reported
by Naeimi et al., [144]. The complexes have been synthesized using Schiff bases
formed by condensation of 5-nitro-salicylaldehyde with various diamines in alcohol.
The results obtained by spectral and other physico-chemical techniques showed that
the complexes have square-planar geometry (45).
Binuclear transition metal complexes
Synthesis of binuclear complexes in which a ligand structure maintains two
metal centers in close proximity but in different compartments separated by an
intervening group represents an important current objective in coordination chemistry.
These complexes serve as simple models for multi-metal-centered catalysts and
multielectron-transfer reagents [145-148]. The orientation of the metal centers, and
hence the nature of the metal–metal interactions, are controlled via appropriate
bridging ligands [149, 150].
Binuclear copper(II) complexes are of interest as models for investigating
intramolecular magnetic-exchange interactions between two metal centers in different
structural motifs, viz. the „„paddle-wheel‟‟ di-copper(II) tetracarboxylates,
symmetrically dibridged hydroxo or alkoxo species, and asymmetrically di-bridged
complexes with a (l-hydroxo/alkoxo)(l-carb-oxylato)dicopper(II) core [151-160].
Dicopper(II) complexes are also important as precursors in the chemistry of
CHAPTER I
23
supramolecular and discrete molecular high-nuclearity copper(II) complexes [161–
170].
Azza [171] have synthesized the Schiff base (46) by the condensation of
bicarboxyl compound 4, 6-diacetylresorcinol with 2-aminobenzenthiol in the 1:2
molar ratio and their binuclear Cu(II), Co(II), Ni(II), Zn(II) and Ru(III) complexes.
The results obtained by spectral and other physico-chemical techniques showed that
ligand acts as tetrabasic hexadentae ligand, bonding sites are azomethine nitrogen
atoms, sulfur atoms and phenolic oxygen atoms.
Kulkarni et al., [172] have synthesized the binuclear transition metal
complexes of bicompartmental SNO donor ligands (47 and 48). Ligand (47) act as
hexadentate tetrabasic for Co(II), Ni(II) and Cu(II) complexes and hexadentate
dibasic chelate for Zn(II) complex. On the other hand ligand (48) is hexadentate
tetrabasic for Cu(II) and dibasic for Co(II), Ni(II) and Zn(II) complexes. Both the
ligands provide SNO donating sites to each metal ion in the binuclear complexes.
Cu(II) and Zn(II) complexes of both ligands have square-planar and tetrahedral
geometry, respectively. Whereas Co(II) and Ni(II) complexes are of octahedral
geometry.
CHAPTER I
24
1.2.PRESENT WORK
The major objectives of the present work are
i. To develop methodology for the synthesis of novel bicompartmental and
heterocyclic Schiff base ligands derived from indole, benzo[b]thiophene,
coumarin moieties which have been utilized in the present work.
ii. To synthesize Cu(II), Co(II), Ni(II) and Zn(II) complexes derived from the above
ligands.
iii. To elucidate the structures of the synthesized ligands and their complexes by
making use of various physico-chemical and spectroscopic techniques. viz. IR, 1H
NMR, mass, UV-Vis., thermal, ESR and powder X-ray diffraction etc.
Electrochemical behaviour of some metal complexes has been studied by the
cyclic voltammetry.
iv. With respect to the significant applications of Schiff base ligands and their metal
complexes in medicinal field, appropriately termed as “Medicinal Inorganic
Chemistry”, Schiff bases and their metal complexes synthesized in the present
study have been evaluated for their antibacterial and antifungal activities. Also
some of the selected ligands and their metal complexes have been tested for their
DNA cleavage properties on isolated genomic DNA of various human pathogens
by agarose gel electrophoresis method and antioxidant activity by di(phenyl)-
(2,4,6-trinitrophenyl)iminoazanium (DPPH) method .
The above studies will be presented in the subsequent seven chapters (Chapter I-
VII). Each chapter begins with an introduction followed by discussion of results.
CHAPTER I: -This chapter deals with the overview of general discussion to Schiff
bases, mononuclear and dinuclear transition metal complex of
heterocyclic and bicompartmental Schiff base ligands.
CHAPTER II: - It deals with the synthetic procedures of ligands (H2L1, H2L2, H2L3,
H2L4, HL5, HL6, HL7 and L8) and their copper(II), cobalt(II),
nickel(II) and zinc(II) complexes. It also describes different physico-
chemical and spectroscopic techniques used for the structural
elucidation of the ligands and their complexes synthesized.
CHAPTER I
25
Methodology carried out for the antimicrobial, DNA cleavage and
antioxidant activity screening has also been described in this chapter.
CHAPTER III: - This chapter describes the characterization of bicompartmental
Schiff bases ligands 5 -substituted-N'-(1 -(5 - 1 -(2 -(5 - substituted -
3a, 7a-dihydro- 1H-indole- 2 -carbonyl)hydrazono)ethyl)- 2, 4 -
dihydroxyphenyl)ethylidene)-1H-indole- 2 -carbohydrazide (H2L1
and H2L2) and their copper(II), nickel(II) and zinc(II) complexes. The
ligands have been characterized by elemental analysis, IR, 1H NMR
and ESI-mass spectral techniques whereas the complexes have been
characterized by elemental analysis, IR, 1H NMR, ESI-mass, electronic
spectra, conductivity measurements, magnetic susceptibility, ESR,
TGA and powder-XRD methods. Electrochemical behaviour of Cu(II)
complex of ligand H2L1 has been studied by the cyclic voltametry.
Antimicrobial activity evaluation of the synthesized ligands and their
complexes were carried out. DNA cleavage activity of ligand H2L1 and
its complexes and ligand H2L2 and its Cu(II) complexes has been
carried out and their results have been discussed.
CHAPTER IV: - This chapter explains the characterization of bicompartmental
Schiff bases ligands (N',N'',N',N'')-N',N''-(1,1'-(4,6-dihydroxy-1,3-
phenylene)bis(ethan-1-yl-1-ylidene))bis(3-chloro-6-substituted
benzo[b]thiophene-2-carbohydrazide) (H2L3 and H2L4) and their
copper(II), cobalt(II), nickel(II) and zinc(II) complexes. The ligands
have been characterized by elemental analysis, IR, 1H NMR and ESI-
mass spectral techniques whereas the complexes have been
characterized by elemental analysis, IR, 1H NMR, ESI-mass, electronic
spectra, conductivity measurements, magnetic susceptibility, ESR,
TGA and powder-XRD methods. Electrochemical behaviour of Cu(II)
complexes of both the ligand has been studied by the cyclic
voltametry. Antimicrobial screening of the synthesized ligands and
their complexes were carried out. DNA cleavage and antioxidant
activity of ligand H2L3 and its complexes were tested and their results
have been discussed.
CHAPTER I
26
CHAPTER V: - It deals with the characterization of Schiff bases ligands 5-
substituted-N'-((7-hydroxy-4-methyl-2-oxo-2H-chromen-8-
yl)methylene)-3-phenyl-1H-indole-2-carbohydrazide (HL5 and
HL6) and their copper(II), cobalt(II), nickel(II) and zinc(II) complexes.
The ligands have been characterized by elemental analysis, IR, 1H
NMR and ESI-mass spectral techniques whereas the complexes have
been characterized by elemental analysis, IR, 1H NMR, ESI-mass,
electronic spectra, conductivity measurements, magnetic susceptibility,
ESR, TGA and powder-XRD methods. Electrochemical behaviour of
Cu(II) complexes of both the ligand has been studied by the cyclic
voltametry. Antimicrobial screening of the synthesized ligands and
their complexes were carried out. DNA cleavage and antioxidant
activity of ligand HL5 and its complexes were tested and their results
have been discussed.
CHAPTER VI: - This chapter describes the characterization of Schiff base ligand 3-
chloro-N'-((7-hydroxy-4-methyl-2-oxo-2H-chromen-8-
yl)methylene)benzo[b]thiophene-2-carbohydrazide (HL7) and its
copper(II), cobalt(II), nickel(II) and zinc(II) complexes. The ligand has
been characterized by elemental analysis, IR, 1H NMR and ESI-mass
spectral techniques whereas the complexes were characterized by
elemental analysis, IR, 1H NMR, ESI-mass, electronic spectra,
conductivity measurements, magnetic susceptibility, ESR and TGA
methods. Electrochemical behaviour of Cu(II) complex has been
studied by the cyclic voltametry. Antimicrobial, DNA cleavage and
antioxidant activity screening of the synthesized ligand and its
complexes were carried out and their results have been explained.
CHAPTER VII: - This chapter deals with the characterization of Schiff base ligand
5-chloro-N'-(4-(dimethylamino)benzylidene)-3-phenyl-1H-indole-
2-carbohydrazide (L8) and its copper(II), cobalt(II), nickel(II) and
zinc(II) complexes. The ligand has been characterized by elemental
analysis, IR, 1H NMR and ESI-mass spectral techniques whereas the
complexes have been characterized by elemental analysis, IR, 1H
NMR, ESI-mass, electronic spectra, conductivity measurements,
CHAPTER I
27
magnetic susceptibility, ESR, TGA and powder-XRD methods.
Antimicrobial screening of the synthesized ligand and its complexes
were carried out. DNA cleavage and antioxidant activity of ligand L8
and its complexes were tested.
SUMMARY AND CONCLUSIONS: -At the end of the thesis overall summary of
the present work with general conclusions on the bonding modes of the
Schiff base ligands and their metal complexes along with a brief
account of the possible routes and scope for further work in this field
has been dealt with.
CHAPTER I
28
REFRENCES
[1] A.B.P. Lever; “Comprehensive Coordination Chemistry II” Vol. 1, Elsevier,
(2003).
[2] G.F.R. Parkin; “Comprehensive Coordination Chemistry II” Vol. 3, Elsevier,
(2003).
[3] D. Banerjea; “Coordination chemistry”, Tata Mcgraw-Hill publishing
company limited, (1990).
[4] R.H. Crabtree; “The Organometallic Chemistry of The Transition Metals”,
Fourth Ed., John Wiley & Sons, Inc., Publication, (2005).
[5] D. Chen and A.E. Martell, Inorg. Chem., 26 (1987) 1026.
[6] H.J. Knolker, Chem. Soc. Rev., 28 (1999) 151–157.
[7] R. Sharma, R. Bala, R. Sharma and P. Venugopalan, J. Coord. Chem., 57(17-
18) (2004) 1563.
[8] Jian-zhang Li, Jia-qing Xie, Wei Zeng, Xiao-yao Wei, Bo Zhou, Xian-cheng
Zeng and Sheng-ying Qin, Transition Metal Chem., 29 (2004) 488.
[9] F.A. Cotton, J. Chem. Soc. Dalton Trans., (2001)1961.
[10] Y. Ibrahim and C. Alaaddin, Transition Met. Chem., 28 (2003) 399.
[11] A.R. Sarkar and S. Mandal, Synth. React. Inorg.Met.-Org. Chem., 30 (2000)
1477.
[12] A.P. Mishra and M. Khare, J. Indian Chem. Soc., 77 (2000) 367.
[13] N.C. Kasuga, K. Sekino and M. Ishikawa, J. Inorg. Biochem., 96 (2003)
298.
[14] F. Cavanagh, Analytical Microbiology, New York: Academic Press, (1963).
[15] F. Offiong, N. Emmanuel and A. Aye, Transition Met. Chem., 25 (2000)
369.
[16] M.V. Almeida, S.D. Chaves and S.P.A. Fontes, J. Braz. Chem. Soc., 17
(2006) 1266.
[17] D. Choudhary, S. Poul, R. Gupta and J. H. Clark, Green Chem., 8 (2006)
479.
[18] M.K. Biyala, N. Fahmi and R.V. Singh, J. Iranian Chem. Soc., 2 (2005) 40.
[19] M.K. Biyala, N. Fahmi and R.V. Singh, Indian J. Chem., A, 45 (2006) 1999.
[20] O.V.S. Heath and J.E. Clark, Nature, 178 (1957) 600.
[21] K.N. Raymond, (Ed.), Bioinorganic Chemistry, Washington: A.C.S., (1977).
CHAPTER I
29
[22] R.J. Sanderson, “Chemical Periodicity”, East-West Press, Pvt. Ltd., New
Delhi (1969).
[23] R.J.P. Williams, H.A.O Hill and J.M. Pratt, Chem. Brit., (1969) 156.
[24] E. Bayer, Ber., 90 (1975) 2325.
[25] R.W. Layer, Chem. Rev., 63 (1963) 489.
[26] F.P. Dwyer and D.P. Mellor; “Chelating Agents and Metal Chelates”,
Academic Press, New York, (1962).
[27] B.U. West; “The Chemistry of Coordination Compounds of Schiff Bases in
New Pathways in Inorganic Chemistry”, Cambridge Univ. Press, (1968).
[28] W. Wang, F. X. Zhang, J. Li and W. B. Hu., Russian J. Coord. Chem., 36
(2010) 33.
[29] H. Schiff, Ann. Chem. Pharm., 150 (1869) 193.
[30] C.K. Jorgensen, Acta Chem. Scand., 11 (1957) 73.
[31] P. Pfeiffer, T. Hesse, H. Pfitzinger, W. Scholl and H. Thielert, J. Prakt.
Chem., 149 (1937) 217.
[32] P. Pfeiffer, E. Buchholz and O. Baver, J. Prakt. Chem., 129 (1931) 163.
[33] G. Mohamed, M.M. Omar and A. Ibrahim, Eur. J. Med. Chem., 44 (2009)
4801.
[34] V.P. Singh, P. Gupta and N. Lal, Russ. J. Coord. Chem., 34 (2008) 270.
[35] H. Schiff, Ann. Chim.(Paris), 131 (1864) 118.
[36] S. Dayagi and Y. Degani, „The Chemistry of the Carbon-Nitrogen Double
Bond‟, ed. S. Patai, Wiley-Interscience, New York, (1970) 71.
[37] M. Calligaris and L.Randccio in „Compahensive coordination Chemistry‟,
eds., G.Wilkinson, R.D. Gillard and J.A.Mccleverty Pergaman, Oxford,
(1987), Vol.2 Chapter 20.1
[38] Z. Cimerman, S. Miljanic and N. Galic, Croatica. Chemica. Acta., 73 (2000)
81.
[39] A. Elmali, M. Kabak and Y. Elerman, J. Mol. Struct., 477 (2000) 151.
[40] M. Valcarcel and M. D. Laque de Castro, “Flow-throgh Biochemical
Sensors”, Elsevier, Amsterdam (1994).
[41] U. Spichiger-Keller, “Chemical Sensors and Biosensors for Medical and
Biological Applications”, Wiley-VCH, Weinheim (1998).
[42] J.F. Lawrence and R.W. Frei, “Chemical Derivatization in
Chromatography”, Elsevier, Amsterdam (1976).
CHAPTER I
30
[43] S. Patai, “The Chemistry of the Carbon-Nitrogen Double Bond”, John Wiley
& Sons, London (1970).
[44] E. Jungreis and S. Thabet, “Analytical Applications of Schiff bases”,
Marcell Dekker, New York (1969).
[45] N. Soltani, M. Behpour, S. M. Ghoreishi and H. Naeimi, Corr. Sci., 52
(2010) 1351.
[46] C.M. Metzler, A. Cahill and D. E. Metzler, J. Am. Chem. Soc., 102 (1980)
6075.
[47] C. Spinu, M. Pleniceanu and C. Tigae, Turk. J. Chem., 32 (2008) 487.
[48] B. Clarke, N. Clarke, D. Cunningham, T. Higgins, P. McArdle, M. N.
Cholchu and M. O. Gara, J. Organometallic. Chem., 559 (1998) 55.
[49] S. N. Pandeya, D. Sriram, G. Nath and E. De Clercq, Pharm. Acta Helv., 74
(1999) 11.
[50] S.N. Pandeya, D. Sriram, G. Nath and E. de Clercq, Arzneimittel Forsch., 50
(2000) 55.
[51] W.M. Singh and B. C. Dash, Pesticides., 22 (1988) 33.
[52] J.L. Kelley, J.A. Linn, D.D. Bankston, C.J. Burchall, F.E. Soroko and B.R.
Cooper, J. Med. Chem., 38 (1995) 3676.
[53] G. Turan-Zitouni, Z.A. Kaplancikli, A. Ozdemir and P. Chevallet, Arch.
Pharm. Chem. Life Sci., 340 (2007) 586.
[54] M.T.H. Tarafder, A. Kasbollah, N. Saravanan, K.A. Crouse, A.M. Ali and
K.T. Oo, J. Biochem. Mol. Biol. Biophys., 6 (2002) 85.
[55] S. Gaur, Asian. J. Chem., 15 (2003) 250.
[56] M.J. Geni, C. Biles and B. J. Keiser, J. Med. Chem., 43 (2000) 1034.
[57] R. Uma, M. Palanindavar and R.J. Butcher, J. Chem. Soc. Dalton. Trans.,
(1996) 2061.
[58] D. Pucci, A. Bellusci, A. Crispini, M. Ghedini and M. La Deda, Inorg Chim
Acta., 357 (2004) 495.
[59] C. Biswas, M.G.B. Drew, A. Figuerola, S. Gomez-Coca, E. Ruiz, V.
Tangoulis and A. Ghosh, Inorg Chim Acta., 363 (2010) 846.
[60] A.D. Garnovski, A.L. Nivorozkhin and V.I. Minkin, Coord. Chem. Rev.,
126 (1993) 1.
[61] S. Kumar, D.N. Dhar and P.N. Saxena, J. Scientific and Industrial Res., 68
(2009) 181.
CHAPTER I
31
[62] H.Y. Zhang, J. Lei, Y.Y. Chen, Q.A. Wu, Y.S. Zhang and L.H. Gao, Synth.
React. Inorg. Met.-Org. Chem., 31 (2001) 973.
[63] E. Abele, Main. Group. Met. Chem., 28 (2005) 45.
[64] Z.A. Siddiqi, Md. Khalid and S. Kumar, Eur. J. Med. Chem., 44 (2010) 264.
[65] D.H. Brown and W.E. Smith, “Enzyme Chemistry - Impact and
Applications”, Chapmann and Hall, London (1990).
[66] E. Canpolat and M. Kaya, J. Coord. Chem., 57 (2004) 1217.
[67] M. Yildiz, B. Dulger, S.Y. Koyuncu and B.M. Yapici, J. Indian. Chem. Soc.,
81 (2004) 7.
[68] N.J. Long, Angewandte Chemie International Edition, 34 (1995) 21.
[69] S. Di Bella, I. Fragata, I. Ledoux, M.A. Draz-Garcia, P.G. Lacroix and T.J.
Marks, Chemistry of Materials., 6 (1994) 881.
[70] W.M. Laidlaw, R.G. Denning, T. Verbiest, E. Chauchard and A. Persoons,
Nature., 363 (1994) 58.
[71] M. Calvin and N. Berkelow; J. Amer. Chem. Soc., 68, (1946) 949.
[72] J.P. Tandon and R.V. Singh, Quart. Chem. Rev., 1 (1984) 88.
[73] V. Casellato, P.A. Vigoto and M. Vidali, Coord. Chem. Rev., 23 (1977) 31.
[74] N.S. Dixit and C.C. Patel, J. Indian Chem. Soc., 54 (1977) 176.
[75] M. Calligaris, G. Nardin and L. Randacio, Coord. Chem. Rev., 7 (1972) 385.
[76] L.F. Wang, Y. Zhu and Z.Y. Yang, Polyhedron., 10 (1991) 2477.
[77] J.G. Wu, R.W. Deng and Z.N. Chen, Trans. Met. Chem., 18 (1993) 23.
[78] Z.Y. Yang, Synth. React. Inorg. Met-Org. Chem., 30 (2000) 1265.
[79] D.R. Williams, “The Metals of Life”, Van Nostrand Reinhold, London
(1971).
[80] J.R.J. Sorenson, J. Med. Chem., 19 (1976) 135.
[81] Z.Y. Yang, Synth. React. Inorg. Met-Org. Chem., 30 (2000) 1265
[82] L.F. Wang, Y. Zhu, Z.Y. Yang, J.G. Wu and Q. Wang, Polyhedron, 10
(1991) 2477.
[83] D.H. Brown, W.E. Smith and J.W. Teape, J. Med. Chem., 23 (1980) 729.
[84] A. Bravo and J.R. Anacona, J. Coord. Chem., 44 (1988) 173.
[85] J.R. Anacona and E.M. Figueroa, J. Coord. Chem., 48 (1999) 181.
[86] J.A. Bakir, Jeragh and Ali El-Dissouky, J. Coord. Chem., 58 (2005) 1029.
[87] M.B. Halli, A.C. Hiremath and N.V. Huggi, Indian J. Chem., 40A (2001)
645.
CHAPTER I
32
[88] K. Hussain Reddy and P. Samhsiva Reddy, J. Indian Chem. Soc., 79 (2002)
132.
[89] Z.Y. Yang, Synth. React. Inorg. Met-Org. Chem., 32 (2002) 903.
[90] S. Chandra and Sangeetika, J. Indian Chem. Soc., 81 (2004) 203.
[91] J.W. Smith, “The Chemistry of the Carbon-Nitrogen Double Bond”, Ed. S.
Patai, Wiley-Interscience, New York (1970) 239.
[92] H.B. Burgi and J.D. Dunitz, Helv. Chim. Acta, 53 (1970) 1747
[93] L.G. Kuzmina and Yu T. Struchkov, Cryst. Struct. Commun., 8 (1979) 715
[94] F.Vogtle and E.Goldsmith, Angew.Chem.Int.Ed.Engl 14 (1974) 520
[95] A.C. Veronese, C. Cavicchioli, F.D‟Angeli and V. Bertolasi, Gazz. Chim.
Ital., 111 (1981) 153
[96] P.L. Orioli, M.D.Vaira and L.Sacconi, Inorg. Chem., 5 (1966) 400.
[97] Ekk Sinn, Inorg. Chem., 15 (1976) 369.
[98] F.A. Bottino, E. Libertini, O. Puglisi and A. Recca, J.Inorg.Nucl.Chem., 41
(1979) 1725.
[99] J.W. Smith, in “The Chemistry of the carbon-nitrogen double bond”, ed.
S.Patai, Wiley-Interscience, New York, (1970) 235.
[100] S.S. Kandil, G.Y. Ali and Ali-El-Dissouky, Trans.Met.Chem. 27 (2002) 171.
[101] A. Cukurovali, I. Yilmez, H. Ozmen and M. Ahemedzade, Trans. Met.
Chem., 27 (2002) 171
[102] Singh and P. Srivastava, Trans. Met. Chem., 11 (1986) 963.
[103] P.S. Singh and T.B. Singh, Synth. React. Inorg. Met. Org. Chem., 29 (1999)
553.
[104] R. Aurora, F. Stelian, C. Theodor and S. Nicolae, Turk. J. Chem., 33 (2009)
775.
[105] C. Spinu, M. Pleniceanu and C. Tigae, Turk. J. Chem., 32 (2008) 487.
[106] W. Rehman, F. Saman and I. Ahmad, Russ. J. Coord. Chem., 34 (2008) 678.
[107] Tavman, S. Ikiz, A.F. Bagcigil, N.Y. Ozgur and A.K. Seyyal, Turk. J. Chem.,
33 (2009) 321.
[108] V.P. Singh, A. Katiyar and S. Singh, J. Coord. Chem., 62 (2009) 1336.
[109] Razak Gafor Sab and B.H.M. Mruthyunajayaswamy, Inorg. Chem. An
Indian Journal, 5(1) (2010) 22.
[110] R.R. Gagne, R.P. Kreh and J.A. Dodge , J. Am. Chem. Soc. 101 (1979) 101.
[111] U. Casellato, P.A. Vigto and M.V. Vidali, Coord. Chem. Rev., 23 (1977) 31.
CHAPTER I
33
[112] F. Lions and K.V. Mortin, J. Am. Chem. Soc., 75 (1953) 3834; 79 (1957)
2733.
[113] M.R. Litzon, L.F. Power and A.M. That, Aust. J. Chem., 24 (1971) 899.
[114] N. Nawar, M.A. Khattab, M.M. Bekheit and A.H. El-Kaddah, Indian J.
Chem., 35A (1996) 308.
[115] V.M. Naik, M.I. Sambrani and N.B. Mallur, Indian J. Chem., 47A (2008) 1793.
[116] A. Coskun and F. Yilmaz, Turk. J. Chem., 32 (2008) 305.
[117] K.B. Gudasi and T.R. Goudar, Indian J. Chem., 33A (1994) 346.
[118] K.B. Gudasi, T.R. Goudar and M.V. Kulkarni, Indian J. Chem., 43A (2004)
1459.
[119] S. Annarao, Ph. D. Thesis, Gulbarga University, Gulbarga (2007).
[120] P. Bamifield, R. Prince and R.G.T. Miller, Indian J. Chem. Soc. A 1447
(1969).
[121] R.H. Balindgi and A. Chakravorty, Inorg. Nucl. Chem. Let., 9 (1973) 167.
[122] Y. Mutto, Bull. Chem. Soc. Japan, 31 (1958) 1017.
[123] N.V. Kulkarni, G.S. Hegde, G.S. Kurdekar, S. Budagumpi, M.P. Sathisha
and V.K. Revankar, Spectroscopy Letters., 43 (2010) 235.
[124] G. Rajshekhar, B.K. Shanthaveerapa, S.D. Angadi, V.H. Kulkarni and
B.H.M. Mruthyunjayaswamy, Asian J. Chem., 10(2) (1998) 306.
[125] B. Singh and P. Srivastava, Trans.Met.Chem., 11 (1986) 963.
[126] B. Singh, P. Sahai, T.B. Singh, Synth. React. Inorg. Met-Org. Chem., 29(4)
(1999) 553.
[127] Y. Jadegoud, O. B. Ijare, N.N. Mallikarjuna, S.D. Angadi, and B.H.M.
Mruthyunjayaswamy, J. Indian Chem. Soc., 79 (2002) 921.
[128] D. Vivekanand and B.H.M. Mruthyunjayaswamy, Int. J. Chem. Res., 6
(2012) 29.
[129] D. Vivekanand and B.H.M. Mruthyunjayaswamy, Asian J. Research Chem.,
6(1) (2013) 35.
[130] K. Mahendra Raj, V. Biradar and B.H.M. Mruthyunjayaswamy,
Bioinorganic Chemistry and Applications, 2013, (2013) 16.
[131] M. Calligaris and L. Randccio, “Comprehensive Coordination Chemistry”,
Ed. G. Willkison, R.D. Gillard and J.A. Mc Cleverty, Pergamon, Oxford
(1987).
[132] J.V. Dubsky and A Sokol, Collect. Czeeck. Chem. Commun., 3 (1932) 548.
CHAPTER I
34
[133] L. Sacconi, I. Bertim, J. Am. Chem. Soc. 88 (1966) 5180.
[134] G.T. Mogan and J.D. Mainsmith, J. Chem. Soc. (1925) 2033
[135] D. Hall, A.D. Rao, T.N. Waters, Proc. Chem. Soc., (1962) 143.
[136] P. Fantanci, V. Valenti, F. Cariati and Fragala, Inorg. Nucl.Chem. Letts., 11
(1975) 585
[137] J.V. Dubsky, and A. Sokol, Collection of Czeck. Chem. Commun. 3 (1932)
548.
[138] P. Gluvchinsky, G.M. Mockler and E. Sinn, Spectrochim. Acta, 33A (1977)
1073.
[139] T. Tanaka and S. Kono, Bull. Chem. Soc. Japan, 39 (1966) 2558.
[140] K. Hussain Reddy and D. Venkata Reddy, Indian J. Chem., 22A (1983) 824.
[141] P.S. Zacharias and J.M. Elizabeth, Indian J. Chem., 23A (1984) 26.
[142] L.K. Wah Henri, J. Tagenine and B. Minu Gupta, Indian J. Chem., 40A
(2001) 999.
[143] S. Zohezzi, E. Spodine and A. Deciuti, Polyhedron, 21 (2002) 55.
[144] H. Naeimi and M. Moradian, J. Coord. Chem., 63 (2010) 156.
[145] L.V. Penkova, A. Maciag, E.V. Rybak-Akimova, M. Haukka, V.A.
Pavlenko, T.S. Iskenderov, H. Kozlowski, F. Meyer and I.O. Fritsky. Inorg.
Chem., 48, (2009) 6960.
[146] C. Camacho-Camacho and G. Merino. Eur. J. Inorg. Chem., 1021 (1999).
[147] F.R. Keene, J.A. Smith and J.G. Collins. Coord. Chem. Rev., 253 (2009)
2021.
[148] S.J. Lippard, J.M. Berg, Principles of Bioinorganic Chemistry, University
Science Books, Mill Valley, CA (1994).
[149] K. Singh, Dharampal and V. Parkash, Phosphorus, Sulfur Silicon Relat.
Elem., 183, (2008) 2784.
[150] P. Chaudhuri, V. Kataev, B. Buchner, H.H. Klauss, B. Kersting and F.
Meyer. Coord. Chem. Rev., 253 (2009) 2261.
[151] M. Kato and Y. Muto, Coord. Chem. Rev., 92 (1988) 45; M. Melnik, Coord.
Chem. Rev. 42 (1982) 1981; R.J. Doedens, Prog. Inorg. Chem. 21 (1976)
209.
[152] W.E. Hatfield, Comments Inorg. Chem., 1 (1981) 105; D.J. Hodgson, Prog.
Inorg. Chem., 19 (1975) 173; V.H. Crawford, H.W. Richardson, J.R.
Wasson, D.J. Hodg-son and W.E. Hatfield, Inorg. Chem. 15 (1976) 2107.
CHAPTER I
35
[153] O. Kahn and Angew. Chem., Int. Ed. Engl. 24 (1985) 834; O. Kahn,
Comments Inorg. Chem., 3 (1984) 105.
[154] P.J. Hey, J.C. Thibeault and R. Hoffmann, J. Am. Chem. Soc., 97 (1975)
4884.
[155] W. Mazurek, B.J. Kennedy, K.S. Murray, M.J. OConnor, J.R. Rodgers,
M.R. Snow, A.G. Wedd and P.R. Zwack, Inorg. Chem., 24 (1985) 3258.
[156] Y. Nishida, M. Takeuchi, K. Takahashi and S. Kida, Chem. Lett., (1982)
1815; Y. Nishida, M. Takeuchi, K. Takahashi and S. Kida, Chem. Lett.,
(1985) 631.
[157] Y. Nishida and S. Kida, J. Chem. Soc., Dalton Trans., (1986) 2633.
[158] M. Handa, N. Koga and S. Kida, Bull. Chem. Soc. Japan, 61 (1988) 6853.
[159] K. Geetha, M. Nethaji, N.Y. Vasanthacharya and A.R. Chakravarty, J.
Coord. Chem. 47 (1999) 77; S. Meenakumari, S.K. Tiwari and A.R.
Chakravarty, J. Chem. Soc., Dalton Trans., (1993) 2175; K. Geetha, M.
Nethaji, A.R. Chakravarty and N.Y. Vasanthacharya, Inorg. Chem., 35
(1996) 7666.
[160] T.N. Sorrell, C.J. OConnor, D.P. Anderson and J.H. Reibenspies, J. Am.
Chem. Soc., 107 (1985) 4199; V. McKee, M. Zvagulis, J.V. Dagdigian,
M.G. Patch, C.A. Reed, J. Am. Chem. Soc., 106 (1984) 4765.
[161] R.E.P. Winpenny, Adv. Inorg. Chem., 52 (2001) 1.
[162] S.P. Perlepes, E. Libby, W.E. Streib, K. Folting and G. Christou,
Polyhedron, 8 (1992) 923.
[163] S.R. Batten, B.F. Hoskins, B. Moubaraki, K.S. Murray and R. Robson,
Chem. Commun., (2000) 1095; B. Graham, M.T.W. Hearn, P.C. Junk, C.M.
Kepert, F.E. Mabbs, B. Moubaraki, K.S. Murray and L. Spiccia, Inorg.
Chem., 40 (2001) 1536.
[164] M.L. Tong, K.H. Lee, Y.X. Tong, X.M. Chen and T.C.W. Mak, Inorg.
Chem., 39 (2000) 4666.
[165] V. Tangoulis, C.P. Raptopoulou, S. Paschalidou, E.G. Bakalbassis, S.P.
Perlepes and A. Terzis, Angew. Chem., Int. Ed. Engl. 36 (1997) 1083; V.
Tangoulis, C.P. Raptopoulou, A. Terzis, S. Paschalidou, S.P. Perlepes and
E.G. Bakalbassis, Inorg. Chem., 36 (1997) 3996; H. Annetha, K.
Panneerselvam, T.F. Liao, T.H. Lu and C.S. Chung, J. Chem. Soc., Dalton
Trans. (1999) 2869.
CHAPTER I
36
[166] A. Mukherjee, I. Rudra, M. Nethaji, S. Ramasesha and A.R. Chakravarty,
Inorg. Chem., 42 (2003) 463.
[167] K. Geetha, M. Nethaji and A.R. Chakravarty, Inorg. Chem., 36 (1997) 6134.
[168] A. Mukherjee, M. Nethaji and A.R. Chakravarty, Angew. Chem., Int. Ed. 43
(2004) 87.
[169] A. Mukherjee, M. Nethaji and A.R. Chakravarty, Chem. Commun., (2003)
2978.
[170] A. Mukherjee, I. Rudra, S.G. Naik, S. Ramasesha, M. Nethaji and A.R.
Chakravarty, Inorg. Chem., 42 (2003) 5660.
[171] A.A.A. Abou-Hussein, J. Sulfur Chem., 31(5) (2010) 427.
[172] N.V. Kulkarni, M.P. Satisha, S. Budagumpi, G.S. Kurdekar and V.K.
Revankar, J. Coord. Chem., 63(8) (2010) 1451.