Download SYNTHESIS AND CHARACTERISATION OF TRANSITION AND

SYNTHESIS AND CHARACTERISATION OF
TRANSITION AND INNER-TRANSITION
METAL COMPLEXES USING BIOLOGICALLY
ACTIVE TRIAZOLE
INTRODUCTION
The compounds containing thione (>C=S)
and thiol
(>C-SH)
groups occupy prominant role in organic reagents. They possess
, .
.
applications
many
m
. ,
41-43
industry
,
analytical48 50 chemistry.
study,
ie.
.
m
„. .
44-47
medicine
and
in
The compounds used in the present
3-substituted-4-amino-5-mercapto-l,2,4-triazoles
belong to the above class of organic compounds.
In recent years,
a number of transition metal complexes
of heterocyclic thiones have been studied
are capable of undergoing thiol-thione
51-53
.
Such ligands
(-N=C-SH
-NH-C=S)
tautomerism and can act as mono as well as polydentate ligands.
The Chemistry of 1,2,4-triazoles have been reviewed by Kroger
et al
54
Triazoles have a wide range of applications.
,
reported
to
.
.
,55
anti-viral
,
possess
anti-tumor and analgesic activities.
used
as
literature
analytical
reveals
reagents
that
a
57
lot
.
of
. ,
56
anti-inflammatory ,
The
An
triazoles
exhaustive
work has
tridentate
Schiff
bases
with
are
survey
also
of
been done on the
complexes of 1,2,4-triazole with various metals
The
They are
58-66
heterocyclic
amines
containing ONS sequence have been tried for complexation with
transition metals
such as
32
copper(II),
nickel(II),
cobalt(II),
zinc(II)
and
cadmium(II).
The
copper(II)
shows
bivalent
tridentate behaviour and forms dimeric complexes. This has been
substantiated
by
sub
normal
magnetic
moments
and
electronic
have synthesised eobalt(II),
copper(II)
.
67
spectra
Garg et
and nickel(II)
have
al
nickel(II)
,
complexes of 5-mercapto-l,2,4-triazoles and they
assigned
complexes.
68
distorted
octahedral
geometry
Recently, Gadag and Gajendragad
and copper(II)
69
for
these
have prepared the
complexes with 3-methyl and 3-ethyl
derivatives of 4-amino-5-mercapto-l,2,4-triazole and they have
assigned the high spin octahedral type configuration as shown
below.
H2Q
H20
M = Ni(II), Co(II)
Literature
also
records
the
complexing
ability
of
3-aryloxy-4-aryl-5-mercapto-l,2,4-triazoles with bivalent metal
33
ions
70
.
In this case, X-ray studies reveal that the complexes
possess
cubic
structure.
The
fungi
toxicity of
the complexes
and the free ligands has been evaluated against H. Oryzae.
Pannu et
nickel(II),
complexes
al
71
, have reported manganese(II), cobalt(II),
copper(II),
of
zinc(II),
cadmium(II)
4n-Butyl-4H-l,2,4-triazole
in
and mercury(II)
which
the
ligand
shows bidentate behaviour in all the complexes except those of
cadmium(II) and mercury(II).
Recently, Garag et
cobalt (II),
al
nickel(II)
72
, have reported tne complexes of
and
hydrazino-1,2,4-triazole
copper (II)
hydrochloride
and
with
have
4-amino-3assigned
the
high spin distorted octahedral geometry for all the complexes
on the basis of magnetic and spectral data.
H2N H2°
H2
n-n
-N„
N=
X
3—N-N^'^N
w
H2
I
N
Nv
H20
M
Recently,
cobalt(II),
bases
nh2
physico-chemical
nickel(II)
have
:N
Co (II), Ni(II) and Cu(II)
and
have been reported
coworkers 74
H
in
copper(II)
the
synthesised
34
studies
chromium(III),
complexes
literature
and
of
73
.
with
Schiff
Hiremath and
characterised
the
metal
complexes of aromatic heterocyclic Schiff bases on the basis of
analytical and spectral data.
Mxshra
et
nickel (II),
al
75
,
have
copper(II)
and
3- amino-5-(a/b)pyridylrecords
76
the
reported
the
zinc(II)
complexes
1,2,4-triazoles.
complexes
of
some
cobalt(II),
Literature
bivalent
metal
ions
with
also
with
4- salicylaldiamino-3-mercapto- 5-phenyl-1,2,4 - triazole.
Chromium(III), iron(III) and ruthenium(III) complexes of
3-methyl-4-benzylidineimino-5-mercapto-1,2,4-triazole have been
reported
m
complexes
the
have
literature
been
77
.
These
characterised
by
bivalent
magnetic
metal
and
ion
spectral
studies and were assigned the low spin octahedral geometries.
Kaushik et
al
78
, have used triazoles as ligands for the
complexation of bivalent metal ions.
on
the
data.
basis
of
analytical,
Transition metal(II)
These were characterised
magnetic,
thermal
and
spectral
complexes of triazole derivatives
have been synthesized by Satpathy and coworkers
79-82
and they
have assigned octahedral geometry around the metal ions chosen,
except
cobalt(II)
proposed.
for
which
a
tetrahedral
geometry
was
The ligand as well as the complexes were tested for
their toxicity against
two fungi
such as
Fusarium oxysporium
and Helminthosporium Oryzae by Horsfall method.
35
The copper(II)
complex exhibited more fungi toxicity.
Electrochemical
with
al
83
triazole
.
properties
derivatives
Literature
84
of
have
Ruthenium(III)
been
studied
by
complexes
Fennena
et
also records the X-ray studies of zinc(II)
chloride complexes with 4-amino-3,5-dimethyl-1,2,4- triazole.
Vos et
of
al
85
, have studied the photo physical properties
Ruthenium(III)
1,2,4-triazole
complexes
ligands.
Reaction
triazole with palladium(II)
and co-workers
containing
of
3 -(Pyrazine-2-yl)
3,5-diamino-1,2,4 -
compounds has been studied by Grap
86
Coordination
compounds
of
4-amino-1,2,4-triazole
with
metal chelates, bromates and nitrates have been appeared in the
literature
have
87
been
Rhenium(V)
studied
cobalt (II),
88
complexes with triazole derivatives
Mishra
rhodium(III),
et
al
nickel (II),
89
have
zinc(II)
studied
the
and cadmium(II)
complexes with 4-amino-3-mercapto-l,2,4-triazole.
Ruthenium(II)
been
reported
and
complexes
their
of
Bis-(Pyridyl)triazoles
absorption
spectra,
luminescence
properties and electro chemical behaviour have been studied
Copper(II)
complexes
1,2,4-triazole-5-thione
have
, .
91
literature
36
of
have
90
4 -amino-1,4-dihydro-3-methylbeen
documented
in
the
Ginzburg
complexes
been
of
et al
the
have
by
ESR
copper(II)
have
Verma
of
copper (II)
and
they
et
al
93
,
have
have
The complexes were characterised by
the cobalt(II),
with
the
4-amino-3-hydrazino-5-
magnetic and spectral data.
studied
complexes
spectra.
complexes
mercapto-1,2,4-triazole.
analytical,
synthesised
3-amino-5-carboxy-1,2,4-triazole
characterised
reported
,
Revankar and Mahale
nickel(II)
and
94
copper(II)
3-methylsulfhydryl-4-amino-5-mercapto-1,2,4 -
triazole and they have assigned octahedral configuration on the
basis
of
magnetic and
spectral
data.
They
have also
been
evaluated for their antibacterial and antifungal activities.
Patil and coworkers
complexes
triazole.
with
95
synthesised the transition metal
3-substituted-4-salcylidene-5-mercapto-1,2,4 -
The copper(II) complexes of these ligands are stable
and show no reduction from copper (II)
Zaydoun
iron(II),
et
al
cobalt(II),
96
,
have
nickel(II)
to copper (I) .
reported
the
manganese(II) ,
and copper(II)
complexes with
1,2,4-triazole and they have characterised the complexes on the
basis of analytical, magnetic and spectral data.
Recently Mustafa Kamil Said et al
iron(III)
complexes
triazole and they
with
97
,
have reported the
4-amino-3-mercapto-5-phenyl-1,2,4 -
have assigned the high spin octahedral type
37
configuration.
their
The
complexes
antibacterial,
have
antifungal
and
Antitumour activity of iron(III)
lympocytic leukemia test
also
been
evaluated
antitumour
for
activities.
complex was tested with P388
system in the mice.
P388 cells were
maintained in RPMI-1640 medium supplemented with 5% fetal calf
serum and kanamycin (100 ng/ml).
Sinha
nickel(II)
and
and
coworkers
98
copper (II)
have
reported
complexes
dimercapto-5-phenyl-1,2,4-triazole
with
and
octahedral geometry for cobalt(II),
the
they
cobalt(II),
4-amino~3,5-
have
nickel(II)
assigned
and copper(II)
complexes on the basis magnetic and spectral data.
Very
recently
nickel(II),
Yadawe
and
cobalt(II),
Patil
99
copper(II),
have
studied
the
oxovanadium(IV),
dioxouranium(VI), zirconium(IV), thorium(IV) and lanthanum(III)
complexes of Schiff bases derived from 3-substituted-4-amino5-mercapto-l,2,4-triazole
thiophene-2-aldehyde.
characterised
on
the
with
All
basis
glyoxal/biacetyl/benzil/
the
of
complexes
analytical,
have
spectral
been
and
thermogravimetric data and they have also been evaluated for
their antibacterial, antifungal and antiinflammetry activities.
3-substituted-4-amino-5-mercapto-l,2,4-triazoles
synthesised and characterised by Hosur et al^^
38
were
They studied
the
antibacterial,
antifungal,
anticonvulsant activities.
antiinflammetry
and
Results showed that their compounds
were much potent towards herbicidal activities.
Literature survey revealed that
there
is
no report on
the synthesis and characterisation of metal complexes using the
compounds
prepared by Hosur
et
al.
importance of the above compounds,
synthesise
them.
and
Hence,
synthesis,
characterise
the
the
present
characterisation
and
investigation
characterisation
of
also
Schiff
metal
ions.
bases
4-amino-5-mercapto-l,2,4-triazole
biological
it is worth to
complexes
biological
deals
the
we thought,
investigation
ligands with transition metal
present
Keeping
formed
deals
studies
with
of
the
above
In addition to this,
with
formed
with
the
preparation
from
the
and
3 -substituted-
salicylaldehyde
their transition and inner-transition metal complexes.
39
from
and
EXPERIMENTAL
SYNTHESIS OF LIGANDS
The
following
ligands
are
used
in
the
present
investigation.
1. 3-N-methylmorpholino-4-amino-5-mercapto-l;2,4-triazole
(MMAMT)
2. 3-N-methylpiperidino-4-amino-5-mercapto-l, 2,4-triazole
(MPAMT)
N
\l-CH2
N
SH
3. 3-N-methylmorpholino-4- salicylideneatrtino-5-mercapto-1,2,4triazole
(MMSMT)
40
4. 3-N-methylpiperidino-4-salicylideneamino-5-mercapto-l,2,4triazole (MPSMT)
1. Synthesis of MMAMT
It involves the following stages.
i)
Preparation of ethyl-morpholino-N-acetate
To the ice cold solution of morpholine
(0.4 mol)
in dry
benzene (200 ml), ethyl chloro acetate (0.2 mol) was added with
vigorous
shaking.
The
resultant
steam bath for 8-10 hrs.
washed
with dry
mixture
was
refluxed
on
a
The resulting solid was filtered and
benzene.
The
filtrate
reduced pressure to remove dry benzene.
was
distilled under
The ethyl morpholinoe
N-acetate collected in the flask (B.P. 88-89 C) was used in the
next stage.
ii)
Preparation
Ethyl
hydrate
of
morpholino-N-acethydrazide
morpholino-N-acetate
(0.1 mol)
under
mol)
and
were taken in absolute alcohol
refluxed on a steam bath for 10-12
removed
(0.1
reduced
pressure.
41
hrs.
The
Excess
hydrazine
(50 ml)
and
solvent was
resulting
viscous
hydrazide was cooled and kept under vacuum overnight to get in
solid form. The solid hydrazide obtained was recrystallised in
alcohol to get colourless needles.
iii)
Preparation of potassium-3 -(N-acetyl-morpholino)
dithio-
carbazinate
Morpholino-N-acetahydrazide (0.1 mol),
(0.15
mol)
absolute
and potassium hydroxide
alcohol
12-14 hrs.
voluminous
(200
ml)
and
(0.15
carbon disulphide
mol)
were
stirred continously
It was then treated with dry ether
potassium
dithiocarbazinate.
taken
for
about
\200 ml)
This
was
in
to get
filtered,
washed with dry ether for several times and finally dried under
vaccum.
The potassium
salt
thus
formed was
employed for
the
preparation of triazole without further purification.
iv)
Preparation
of
3-N-methylmorpholino-4-amino-5-mercapto-
1,2,4-triazole
Hydrazine
hydrate
(0.2
potassium-3 -(N-acetylmorpholino)
suspended in water
hrs.
ml)
was
acidified
in white
by
solid
and refluxed with
adding
form.
water and further dried.
42
added
dithiocarbazinate
The resulting homogenous mixture was
carefully
MMAMT
(10
ml)
acetic
This
was
acid
to
the
(0.1
mol)
stirring for 2
cooled in ice and
drop
filtered,
wise
to
get
washed with
Finally it was recrystallised from
alcohol. M.P. 187-188 C.
2. Synthesis of MPAMT
Synthesis of MPAMT is similar to that of MMAMT. However
instead of
MPAMT
morpholine used
in MMAMT,
piperidine
was
used
in
100
3. Synthesis of MMSMT
MMAMT
(0.1 mol)
in absolute alcohol
and salicyaldehyde
(100 ml)
(0.1 mol)
were taken
containing two drops of Cone. HCl
and refluxed on water bath for 4-5 hrs.
The MMSMT separated
after the evaporation of
recrystallised from
the
alcohol was
alcohol. M.P. 204-205°C.
4. Synthesis of MPSMT
MPAMT
(0.1-mol)
in absolute alcohol
and salicyaldehyde
(100 ml)
alcohol. M.P. 193-194 C.
43
were taken
containing two drops of Cone. HCl
and refluxed on water bath for 4-5 hrs.
after the evaporation of
(0.1 mol)
The MPSMT separated
the alcohol was recrystallised from
SYNTHESIS OF COMPLEXES
a)
Synthesis of cobalt (II), nickel(II) and copper(II)
complexes with MMAMT, MPAMT, MMSMT and MPSMT
Metal(II)
appropriate ligand
chloride
(0.01
(0.01 mol)
mol)
was
treated
with
an
in 1:1 ratio in alcoholic medium
and refluxed for about one hr.
2g of sodium acetate was added
to the reaction mixture and further continued refluxation for a
period of
washed
3
with
hrs.
The
alcohol
complex thus
and
finelly
separated was
dried
in
filtered,
vaccum over
fused
calcium chloride.
b)
Synthesis of lanthanide(III) complexes with MPSMT
Lanthanide(III)
MPSMT (0.004 mol)
for about 4 hours.
nitrate
(0.002
mol)
was
treated
with
in 1:2 ratio in absolute alcohol and refluxed
Alcoholic ammonia was added to the reaction
mixture to raise the pH to 6.5 and further refluxed for 2 hrs.
The
complex
alcohol
and
thus
separated
finally
dreid
chloride.
44
was
in
filtered,
vaccum
washed
over
fused
with
dry-
calcium
RESULTS AND DISCUSSION
All the cobalt(II),
of
the
under
yellow
to
taken
dark
nickel(II)
ligands
green
in
are
and copper(II)
brown,
colour
yellowish
respectively.
complexes
green
and
They
are
insoluble in common organic solvents such as ethanol, methanol,
benzene,
chloroform
etc,
however
solvents like DMF and DMSO.
they
are
soluble
The analytical,
in
polar
molar conductance
and magnetic moment data are given in Table I.
Analytical data
reveals
lanthanide(III)
that
metal:ligand
ratio
is
1:1.
The
complexes of MPSMT are pale yellow in colour.
They are soluble
in DMF and DMSO. The analytical and molar conductance data are
given in Table
II.
Analytical data reveals
that metal:ligand
ratio is 1:2.
Molar conductivity measurements
The
copper (II)
molar
conductivity
of
cobalt(II),
complexes measured in DMF at
range 2.15 to 9.78 ohm
-1
2
cm
mol
-1
10
-3
nickel(II)
M.
fall
and
in the
. These values are much less
than expected for 1:1 electrolytes1^1. Hence all complexes are
treated as non-electrolytes. In lanthanide(III) complexes molar
conductance
values
lie
between
19.20-25.30
ohm
-1
cm
indicating that all the complexes are non-electrolytes.
45
2
mol
-1
Table I Analytical, magnetic and conductivity data of Co(II) Ni(II) and Cu(II) complexes with
MAMT, MPAMT, MMSMT and MPSHT
Complex
Compound
ELEMENTAL ANALYSIS %
Molar conductance Magnetic
XM
-1
code
C
C
[Co(WAMT)Cl.(H 0) ]
<•
24.46
H
N
3.62
S
20.28
Cl
M
9.18 10.25
ohm
16.94
2
cm
moment
-1
mol
(B.M)
2.54
4.30
7.74
3.10
2.17
1.32
8.76
4.27
6.41
2.93
9.78
0.86
2
(24.38)(3.48)(20.33 (9.28)(10.39)(17.12)
C
[Ni(mAMT)Cl.(H^0)2]
24.70
3.84 20.42
9.25 10.64
17.24
(24.42)(3.48)(20.34)(9.39)(10.36)(17.05)
C
[Cu(MMAMT)Cl.H20]
25.46
3.42
20.42
9.60 10.55
19.12
(25.36)(3.65)(21.19)(9.66)(10.72)09.30)
C
[Co(MPAMT)Cl.(H20)2]
28.12
3.90 27.98
9.38 10.24
17.16
(28.09)(4.08)(28.02)(9.34)(10.36)(17.22)
C
[Ni(MPAMT)Cl.(H20)2]
28.36
4.18 20.82
9.30
9.78
18.02
(28.07)(4.09)(20.46)(9.40)(10.37)(18.12)
C
[Cu(MPAMT)C1.H20]
28.92
4.12 20.65
9.65 10.56
20.24
6
(29.19)(4.00)(21.27)(9.72)(10.79)(19.46)
C
[Co(MMSMT)(H20)2]
40.57
4.58
13.75
7.75
—
14.25
(40.55)(4.65)(13.55)(7.73)
C
[Ni(MMSMT)(H 0) ]
8
40.62
4.59 13.54
7.65
(14.14)
—
-
14.25
2.77
22
(42.14)(3.85)(16.37)(9.35)
C
4.90
[Cu(hWSMT)]
43.58
3.88
14.50
8.15
(20.52)
—
16.55
1.50
9
(43.92)(3.95)(14.65)(8.44)
C
[Co(MPSMT)(H^0)2]
40.45
4.64 13.75
7.85
(16.63)
—
(40.78)(4.53)(13.53)(7.76)
C
[Ni(MPSMT)(H20)2]
40.75
4.60 13.76
7.84
[Cu(MPSMT)]
44.00
4.05 14.50
8.35
14.35
—
14.10
The results given in parenthesis are theoretical values
46
2.65
(14.21)
—
16.15
12
(44.22)(3.98)(14.75)(8.46)
4.92
(15.67)
(40.82)(4.32)(13.65)(7.77)
C
'
(16.64)
1.55
Table II Analytical, Conductance and Magnetic data of lanthanide (111! nitrate
complexes with ligand MPSMT
Complex
Elemental. Analysis
Complex
code
C:
H
N
(%)
£
M
Molar conductance
^•M
ohm 1
cm
2
B!
[La(MPSMT)^NO ] H 0
3 2
42 . 96
4 . 32
(43 . id (4 . 55!
18 . 57
16 . 3 8
7 . 48
(18..42! (7 . 66) (16 . 64)
22 . 2
B2
[Ce(MPSMT)zN0 3,H2°
4 1 . 82
4 . 72
(42 . 15) (4 . 44 )
17 ..86
7 . 66
16 . 15
(18 ,.03) (7 . 49) (16 . 39)
20 . 4
B3
[Pr(MPSMT)2N0 312H2°
41 ..48
4 .. 82
(41 . 23 ) (4 . 84)
17 ..78
7 . 43
16 . 74
(17 ..64) (7 . 33) (16 . 15)
21 . 6
B
[Nd(MPSMT)2N0 3)2H2°
4 ..73
40 ..95
(40 ..26) (4 ..69)
(17 ..27) (7 . 15) (16 . 10 )
40 ..22
4 .,30
(40 ,. 00) (4 . 66!
17 ..30 6 . 92
(17 .11) (7 . id
3 9 .. 99
4 .. 58
(39 . 91! (4 .. 65!
(17 .07} (7 ..09)
(16 .85!
[Sm(MPSMT)2N0 313H2°
B
B6
[Eu(MPSMT)2N0 313H2°
17 ,. 55
16 . 84
7 . 24
6 . 85
16 . 68
16 .68
21 . 5
25 ,. 3
(16 .66!
16 - 75
20 .. 7
B7
[Gd(MPSMT)2N03 12H2°
40 . 36
4 .. 65
(40 .49) (4 . 72 )
17 .55
7 ..23
(17 .32) (7 .19)
17 .28
(17 . 66 )
19 . 2
B8
[Tb(MPSMT)2N03 ] 2H20
40 . 27
4 . 65
(40 . 40 ) (4 .71)
17 . 18
7 ..00
(17 .28) (7 .18)
17 . 66
(17 . 84 )
20 .. 1
B9
[Dy(MPSMT)2NC>3 ]2H20
40 .12
4 . 42
(40 . 23 ) (4 .69)
17 .46 7 .26
(17 . 27 ) (7 . 32)
18 .65
22 . 9
(18 . 16)
40 . 74
4 .42
(40 . 04 ) (4 . 67)
17 .27 7 .. 32
(17 .13) (7 .11)
(18 . 57)
40 .22
4 . 55
(39 . 77} (4 . 63)
17 .48
6 . 98
<17 .03) (7 . 07)
(19 .11)
43 .46
4 .86
(43 . 84) (5 .id
18 .48
7 .34
(18 .75) (7 .79)
10 .75
(10 .84)
B10
B11
B12
[Er(MPSMT)2N03 )2H20
[Yb(MPSMT)2N03 ] 2H20
[Y(MPSMT)2N031 2H 0
The results given in parenthesis are theoritical values
47
18 . 86
19 .35
22 . 5
24 .. 9
24 . 7
, -1
mo 1
Magnetic moment measurements
Cobalt(II) complexes
Cobalt(II),
form
a d
paramagnetic
tetrahedral
or
7
ion,
having two unpaired electons can
complexes
six
having
coordinated
either
four
octahedral
coordinated
geometry.
The
magnetic susceptibility which decides a particular geometry is
controlled by many factors
like strength of
and degree of the spin orbit coupling.
the ligand field
Cobalt (II)
complexes in
tetrahedral geometry show magnetic moment in the- range 4.2-4.7
B.M.
However
in
octahedral
geometry
the
values
fall
in
the
and C
14
are
range 4.7-5.2 B.M.
The u __ values of
eff
cobalt (II)
complexes C
4.30 and 4.27 B.M. respectively, which are much below the range
expected for octahedral cobalt(II)
magnetic
values
polymeric
suggests
form.
The
complexes are 4.90
are
in
good
that
magnetic
the
with
that
These subnormal
complexes
moment
and 4.92 B.M.
agreement
complexes.
values
may
of
respectively.
of
complexes
exist
C7
and
in
C
These values
of
octahedral
geometry.
Nickel(II) complexes
Q
Nickel(II),
form paramagnetic
a d
ion, having two unpaired electrons can
complexes
48
having
either
four
coordinated
tetrahedral
or
six
coordinated
octahedral
geometry.
The
magnetic susceptibility which decides a particular geometry is
controlled by many factors
like strength of the ligand field
and degree of the spin orbit coupling.
Nickel(II)
complexes in
tetrahedral geometry show magnetic moment in the range 3.6 to
4.1 B.M., where as in octahedral geometry a value of 2.9 to 3.3
B.M. is observed.
In the present
nickel (II)
investigations
complexes C ,
2
C ,
5
C
8
the magnetic moments
and C
11
of
lie in the range 2.93
to 3.15 B.M. expected for octahedral geometry around nickel(II)
ion.
Copper(II) complexes
The assignments of geometry around copper (II)
magnetic property is not
straight
forward.
magnetic moment at room temperature,
ion from
On the basis
copper(II)
compounds
of
9
(d )
can be classified into two main groups.
1)
Majority of these compounds show normal magnetic moments
corresponding
to
one
unpaired
electron
Sometimes higher values upto 2.20
to
orbital
streochemical
contribution.
significance,
49
B.M.
These
but
they
(1.73
B.M.).
are observed due
values
do
have
no
indicate
the
absence of any
appreciable
spin-pairing
between
the
unpaired electrons of the metal atoms.
2)
Some of the copper(II)
compounds, display magnetic moment
values lower than the spin-only value
unpaired
electron
tricoordinated
Example,
copper(II)
(1.73 B.M.)
copper(II)
carboxylates
complexes.
These
magnetic moments are due to some kind of
between
copper centres, either of a
for one
and
subnormal
spin interaction
direct
nature or of
super-exchange type.
The
fall
in
These
magnetic
the
values
range
are
corresponding
magnetic
0.86
lower
to
moments
moments
of
to
1.55
than
the
one
unpaired
can
be
present
B.M.,
copper(II)
at
room
spin only value
electron.
interpreted
in
complexes
temperature.
(1.73
These
terms
copper-copper interaction or complexes may exist
B.M.)
subnormal
of
direct
in polymeric
form.
Lanthanide(III)
complexes
Magnetic moments of lanthanide(III)
in Table III.
the
and
The observed magnetic moments are compared with
theoretical
the
complexes are shown
values
spin-orbit
calculated
50
coupling values
from
Van
Vleck
(the Hund values)
formula
of
the
respective lanthanide ions.
These values agree with each other
except for those of the Sm(III)
and Eu(III)
complexes. However
it is found that the experimental values of all the complexes
including those of Sm and Eu agree with the theoretical values
calculated from Van Vleck formula.
Electronic spectra
Cobalt(II) complexes
Cobalt(II)
ion belongs to d
7
electonic configuration and
can form both tetrahedral and octahedral complexes.
number of six coordinate octahedral cobalt(II)
In a large
complexes, three
spin allowed d-d transitions in the order of increasing energy
are given as follows.
41
(F)
4
4---- Tn
lg
2g
— 4t
(F) 4—
2g
4. '
ig
1
(F)
(V_
2
ig
-5----
(p)
(V
(F)
4t
(F)
ig
(v
3
A band in the range of 7000-10000 cm
to v
admixture
(F)
lg
can be assigned
transition while a multiple band observed in the visible
region near
4T
-1
18000
with
cm
spin
-1
may be
forbidden
assigned
to
transition.
transition
The
4v
A^tF)
2g
m
4
(v ) transition is not normally observed as it is a two
2
51
Table
III
Magnetic
moment
of
lanthanide(III)
nitrate
complexes with MPSMT
Complex
code
Complex
Exptl.
value
(B.M)
Hund's
value
(B.M. )
Van Vleck and
Frank's value
(B.M.)
------B1
[La(MPSMT)2N031.HO
0.00
0.00
0.00
B2
[Ce(MPSMT)NO ].HO
2.46
2.54
2.55
B3
[Pr (MPSMT) 2N03] .2^0
3.66
3.58
3.62
B4
[Nd(MPSMT)2N03].3H 0
3.66
3.62
3.68
B5
[Sm(MPSMT) NO ].3H 0
1.25
0.84
1.65
B6
[EU(MPSMT)2N03].2H20
3.25
0.00
3.40-3.51
B7
[Gd(MPSMT)2N03].2H 0
7.69
7.94
7.94
B8
[Tb(MPSMT)2N03].2H 0
9.64
9.53
9.52
B9
[Dy (MPSMT) 2NC>3] .2H 0
10.04
10.63
10.62
bio
[Er(MPSMT) NO.].2H 0
2 3
2
[Yb(MPSMT) NO ].2H O
2 3
2
[Y(MPSMT)2N03].2H 0
9.60
9.57
9.60
4.89
4.50
4.54
0.00
0.00
0.00
B11
B12
52
electron transition in the strong field.
energy
of
different
transitions
in
The equations for the
the
weak
ligand
field
coupling are given below.
v = 1/2(10 Dq -
15 B')
+ 1/2 [10 Dq + 15B') 2
-
12B'.10 Dq] 1/2
'
v2= 1/2(30 Dq - 15 B') + 1/2 [ (10 Dq + 15B') 2 - 12B'.10 Dq] 1/2
'
v3=
[(10 Dq + 15 B')2 - 12 B',10 Dq]1^2
The values of the ligand field parameters such as Dq, B'
and b can be evaluated using three d-d transitions employing
any one of the following methods.
a) by
fitting v and
transitions
10 Dq = v2 . V;l
B' =
(vx2 - vx v2) / (12 v2 - 27 vi)
b) by
fitting v and -v
10 Dq
M
= 2v,
1
B' = 1/30
transitions
- v.3 + 15 B'
[ — 2iv
- v ) + (-v
2
+ v3
2
+ v v )
1/2
]
The reddish-brown coloured cobalt(II) complexes
C? and C
)
7849-8130 cm
(C , C .
14
showed two d-d bands in the range 19,600-20,830 and
-1
4
which are assinged to T
lg
4
(P)<—— T
lg
(F)
(v ) and
3
4T
(F)<--- 4 T
(F)
(v ) transitions of octahedral cobalt (II)
2g
lg
1
ion 102 .
The vband which involves two electron transition was
not
observed
using Konig's
(Fig.
1) .
However,
equation.
its
The various
53
position was
calculated
ligand field parameters
Fi«.
1
.
Electronic spectrum of lCo(lfliAIIT)Cl (H O)
03
L
o
o
aOmfHHOSSV
ro
like Dq,
B' ,
p and LFSE have been calculated and are given in
Table IV. The v /v
ratio agrees well with reported values for
octahedral cobalt(II) complexes.
Nickel(II) complexes
Nickel(II)
nickel (II)
large
ion
complexes
number
of
has
are
d
8
of
electronic
particular
stereochemical
octahedral nickel(II)
forms.
configuration.
interest
The
The
because
of
spectra
of
complexes exhibit three spin allowed d-d
transitions.
■tm
3Tlg
3T2g
*29
Three
spin
allowed transitions
in
increasing order of
energy are designated as
3A2g(F)
2g(p,^-
3Vf)
3Vf>
(v^
(v3)
The present paramagnetic nickel(II) complexes C , C^, Cg
54
Table IV Electronic spectral data of octahedral cobalt(II) and nickel(II) complexes (in DMF)
Complex
V2
V1
Complex
code
cm
-1
V2
calc .
-1
cm
cm
-1
Dq
cm
-1
B1
cm
3
Vi
-1
LFSE
k cal mol 1
[Co(MMAMT)Cl. (H2°)j ^
8130
17433
20830
930.5
925.0
0.952
2 . 14
21.2
[CO(MPAMT)Cl. (H O)
]
7843
16801
19646
895 . 8
861.0
0.887
2 . 14
20.5
S
[Co(MMSMT)Cl.(H^O)j)
7547
16193
19608
864.6
877.6
0.904
2.15
19.8
cio
[Co(MPSMT)Cl.(H20)
)
8130
17434
20833
930.4
925.1
0.953
2 . 14
2 1.3
C2
[Ni(MMAMT)Cl.(H20) ]
8969
14368
24096
896.9
770.5
0.740
1.68
30.75
S
[Ni(MPAMT)Cl.(HO)
8696
15267
23529
896.6
847.2
0.814
1 . 76
29.81
C8
[Ni(MMSMT)(HO)
10695
17637
24691
1089.5
682 . 9
0.65
1 . 65
35.5
C11
[Ni (MPSMT) (H20)2 3
10753
17762
25126
1075.3
708.6
0.68
1.65
36.9
C
C
1
4
]
Free ion value for cobalt(II)
Free ion value for nickel(II)
55
= 971 cm
-1
,
* 1041 cm 1,
LFSE « 6 Dq; 350 cm
, LFSE - 12 Dq
-1
■ 1 K cal mol
and C
and
3m
T
exhibit three bands at 8696-8969 cm
23529-24096
2g
3
(F) *--- A
2g
respectively,
nickel(II)
0.
by
attributed
cm
3
(F) ,
which
T
lg
3
(F)<--- A
indicates
2g
the
-1
,
to
.
and
(F)
1
14368-15267 cm
the
3
T
octahedral
transitions
lg
r
3
(P,i4--- A
2g
(F)
geometry around
ion. The various ligand field parameters like Dq, B'
v2/v1 and LFSE have been computed using the method described
Drago
103
.
The
values
are
tabulated
in
copper(II),
a
Table
IV.
The
spectrum is reproduced in Fig 2.
Copper(II) complexes
The
orgel
diagram
for
inverted diagram of d1 as shown below.
(t- 5e )
2g g
(t
2g
6e )
g
may
be
with
D
symmetry
symmetry the E
*
g
or
and T
2g
rhombic
levels of
9
ion
is
an
The electron transition
considered
All six coordinated copper(II)
d
as
positive
hole
complexes are tetragonal
with
symmetry
In
D
4h
D free ion term will further
56
V.
.
FiR. 2 Electronic spectrum of [Ni(MMAllT)Cl (H 0)
split into Blg, Alg and B2g, Eg levels respectively. The energy
level sequence will depend on the amount of distortion due to
ligand field and Jahn-Teller effect.
Hence three spin-allowed
transitions are expected in visible and near IR regions for a
copper (II) complex in D
or C
symmetry.
complexes C_ and C
show (Table V) a very broad band of low
3
6
intensity in the region, 17200-17391 cm ^ which can be assigned
2
104
4-—- E
transition
.
In addition to this another band
2g
g
in the region 23529-24691 cm 1 is also seen.
This band may be
to
2
t
due to symmetry forbidden ligand ---- vmetal charge transfer
The band observed above
band.
2700
cm 1 may be
assigned as
105
ligand
Distorted octahedral structure has been proposed on the
basis of electronic spectra.
The electronic
and C
spectra of
the
copper(II)
complexes
Cg
exhibit a broad asymmetric band in the region 16130-
57
Table V Electronic spectral data of copper(II)
cmplexes in
DMF solution.
Complex
Complex
X
max
(nm)
code
C3
C6
[Cu(MMAMT)Cl.HO]
[Cu(MPAMT)Cl.HO]
58
X
max
(cm X)
Assignments
2_
T
,
2_
<--- E
580
17241
405
24691
C T
330
30303
Ligand
575
17391
425
23529
C T
340
29411
Ligand
2g
2t
g
^____2e
2g
g
16080 cm 1 which could be attributed to the d-d transitions.
In
addition
region
to
this,
25000-24560
a
cm
charge transfer band.
high
-1
intensity band observed
could be
considered
as
in
the
ligand-metal
On the basis of electronic spectra,
a
distorted octahedral geometry may be proposed.
complexes
Lanthanide(III)
The
important
electronic
MPSMT and lanthanide(III)
assignments
are
ligand exhibits
cm
_
spectral bands
in
Table
VI.
*
and n—> n
*
one being more intense than the former.
complexes.
No
lanthanide(III)
The
two UV absorption maxima
suffer a slight blue
the
ligand
complexes along with their tentative
presented
assignable to n—> n
of
shift
at
due
to
30156
transitions.
However,
in the spectra of
absorption band
spectrum
f-f
of
and
the
37147
The
latter
these
bands
lanthanide(III)
transition
of
the
ions could be identified in the visible region
in the spectra of all these complexes. This is probably due to
the fact that the f-f bands are weak and are obscured by the
intense charge transfer bands
59
106
Table
VI
Electronic spectral data of lanthanide(III)
complexes with liaand MPSMT
SI.NO.
Complex
1
MPSMT
X
max
cm
Assignments
3
*
30156
37147
2
3
■k
[La(MPSMT)2N03] •H2°
[Ce(MPSMT)2N03] •H2°
30242
n'------V 77
37272
71
77
30185
n
n
*
★
*
37345
71
*
4
[Pr(MPSMT)2N03) •2H2°
30864
TV
35161
71
* 71
■k
n
k
5
[Nd(MPSMT)2N03] . 3H 0
2
30382
77
37148
71
30487
71
k
*
6
[Sm(MPSMT)2N03] . 3H 0
2
*
37037
71
77
k
7
[Gd(MPSMT)2N03] • 2H 0
2
30317
77
37548
77-------^77
30244
n-
k
k
8
[Tb(MPSMT)2N03] . 2H 0
2
■*77
*
37375
77
k
S
[Dy(MPSMT)2N03] . 2H 0
2
30198
n-
* 77
37215
77-
*77
*
*
10
[Er(MPSMT) NO ] . 2H 0
2
3
2
30164
*
77
O
*
to
[Yb(MPSMT)2N03]
to
37350
11
77
30275
77
*
37285
77
'77
k
12
[Y(MPSMT)2N031 • 2H 0
2
60
30284
■77
37265
77
*
Infrared spectral studies
i)
IR
studies
of
MMAMT
and
MPAMT
and
their
cohalt (II),
nickel(II) and copper(II) complexes:
The
infrared
frequencies
of
selected
spectra of MMAMT and MPAMT as well as
groups
in
the
in their corresponding
complexes are tabulated in Table VII. The spectra are presented
in Fig. 3 to 7. The bands at 3271 and 3141 cm 1 and the band at
2570
v(SH)
cm "'’in MMAMT and MPAMT have been assigned to
modes
103
respectively.
Y(NH)
and
The high intensity bands in the
region 1622-1604 and 1579-1567 cm 1 could be assigned to vC=N
frequency of triazole moiety.
The three strong bands at 1510,
1307 and 1030 cm 1 have been respectively assigned to thioamide
bands 107
cm _ i
is
band
(IV)
(I) ,
(II)
assigned
and
(III) .
to N-N
A medium intensity band at 900
stretching vibration.
The
thioamide
which is mainly due to >C=S stretching vibration is
observed at 750 cm 1.
The IR spectra of cobalt(II),
complexes
with
MMAMT and
3430 cm"1 due to v(OH)
MPAMT
nickel(II)
and copper(II)
showed a broad
band around
of coordinated water. The NH stretching
frequency observed at 3271 cm 1 in the ligands have shifted to
3221 cm"1 in the complexes suggesting the coordination of amino
group to metal(II)
ion.
The
61
v(C=N)
frequency
of
triazole
Table VII Infrared frequencies
.
Complex
(in cm 1i of Coin! Ni(II) and Cu(II) complexes with MMAMT, MPAMT
. and MPSMT along with their assignments
Ligand/Complex
V(OH) of V(NH)
code
V (SH)
V(C=N)
Thiamide
V(C=S)
1604
1307
750m
1300
750m
V(M-O)
V(M-N)
water
B1
MMAMT
B2
MPAMT
3271
2570m
1567
3141
3252
2 5 7 Ow
1622
1910
3141
S
[Co(MMAMT!Cl.2H^01
3425br
3200
---
161Obr
1400
680m
4
70m
520m
C2
[Ni(MMAMT)Cl.2H^0]
3 4 0 Obr
3200
---
1617br
1401
675m
4 8 5m
510m
C3
[Cu(MMAMT)Cl.H2OJ
3 4 3 Obr
3200
---
162 Obr
1405
675m
4 80m
485m
c
[Co(MPAMT)Cl.2H 0]
3 4 0 Obr
3150
---
16 2 9br
1400
670m
460m
480m
cs
[Ni(MPAMT)Cl.2H20]
3 4 0 Obr
3221
---
163 Obr
1405
665
4 8 5w
5 0 0m
C6
[Cu(MPAMTC1.HO]
3 4 2 5br
3147
---
163 Obr
1407m
6 8 0m
485m
54 3w
4
V (OH) of
water
B3
MMSMT
B
MPSMT
4
--...
V {OH} of
V(NH)
V(SH!
V(C-N)
phenolic
V(C-O)
V(C-S)
V(M-O)
phenolic
2750
3105
2300
1612s
12 50
755
2765
3105
2360
1610s
1250
755
---
1600s
1285
6 8 0m
4 8 0m
S
[Co(MMSMT)(H20) ]
3400
---
2935
C8
[Ni(MMSMT)(HO)
3425
---
2930
...
1605s
1285
685m
485m
S
[Cu(MMSMT]
---
293 5
...
1600s
1270
685m
4 8 5w
cio
[Co(MPSMT)(HO)
]
3400
---
2931
1603s
1280
6 75w
480m
C11
[Ni(MPSMT)(H20) ]
3410
---
2924
...
1600s
1285
675w
480m
C12
[Cu(MPSMT)]
---
---
2931
...
1600s
1282
6 8 0m
4 85w
]
...
62
---
CM
CM
Wavenumbers (cm-1)
*c
M
n
be
**■4
»I
j
i»
t!
Ui
I
cd
\
co
T i [Til i | i i i i | i i i i | i i i i j
IO
o
o
in
8
CO
in
in
rr
in
o
xr
in
co
aOUBU!UJSUBJl%
o
co
in
CM
rrr “
o
in
F ig .
4 IR
s p e c tr u m o f rC o(10IA IIT )C l . (H
O)
moiety observed in the region 1622-1604 and 1579- 1567 cm 1 in
the spectra of the ligands have shifted to around 1630 cm 1 in
the complexes.
This observation indicates the coordination of
one of the azomethine nitrogen of triazole moiety to the metal
atom.
The shifting of IR band of
v(c=N)
towards higher wave
number is due to the delocalisation of the charge between N, C
and S of triazole moiety in the ligands to only N and C in the
complexes.
The band due to v(c=S) observed at around 750 cm 1
_i
in the ligands undergoes red shift by 70-80 cm ~ in complexes.
This
indicates
the
coordination
of
sulphur
atom
via
,
.
108
deprotonation
ii)
IR
studies
of
MMSMT
and
MPSMT
nickel(II) and copper(II) complexes:
and
The
MPSMT exist both in thiol and thione form.
3105
cm 1 due to
V(NH)
their
ligands
cobalt (II),
MMSMT
and
A broad band around
indicates the thione
form where as a
medium intensity broad band in the 2360-2300 cm 1 region due to
v(SH)
region
represents
2765-2750
bonding.
the
cm
-1
is
form.
due
to
A broad weak band
the
intramolecular
in the
hydrogen
The high intensity band in the region 1612-1610 cm 1
is assigned to V(C=N)
assigned
thiol
to
v(c=N)
group and a strong band at 1575 cm 1 is
of
triazole
ring
.
A
band
m
the
_i
region
1530-1510cm
is
63
due
to
v(C-0)
of
phenolic
group.
500
1000
_______
\
3500
3000
\
52
ji \ 1»'11 jTT. JrrriTTT^TTTJTTT^ t i * i i f jTTTjTM 'iTtT"J"7TT”|T'."i'j"iTTITTTT; ? i * > f i’^mTTTTTTH^T i > j <; ijT77y77TJ7,!T|T77ijT7?^^
O00<D^rC'IOG0<D^<NOC0CDrfr4O00C0^(NOC0<D^fCNOC4
lD-’«l‘^^r
^r^J-<0<0<OCOCOC'4<NC4<NCNT-T-
aouewiuiSUBJi%
r-
r~
r~
'
Wavenumbers (cm-1)
1500
2000
2500
\
Another band of high intensity around 1250 cm
the same phenolic C-0 vibration.
the region 755 cm
-1
and
3425 cm 1 due to v(OH)
bonded
phenolic
C-0
OH
MPSMT
in
the
show a
ligands
appears
corresponding complexes.
In copper(II)
oxygen
bridge
complexes
the positive
observations
oxygen atom of
whereas
in
of
.
band
around
The band due to
1285
cm
and
-1
the
new
all
the
in
complexes the band due
shows a positive shift of
cobalt(II)
is
of
that
in
and
the order of
the
nickel(II)
10-15
copper(II)
cm 1.
complexes
the ligand shows bridging bidentare behaviour
cm 1
and
The
nickel(II)
V(C=N)
indicating
complexes
exhibits
for these complexes appears
coordination
of
azomethine
The strong band at 1575 cm 1 due to VC=N vibrations
triazole ring in the
complexes.
In
shift
cobalt (II)
1600
nitrogen.
99
suggest
monodentate behaviour.
around
broad
, thus offering an unambigous proof for the
phenolic
These
-1
and copper(II)
disappears
around
to the phenolic OH at 1530-1510 cm
-1
nickel(II)
of coordinated water.
vibration
the order 25-35 cm
99
has been assigned to the V(C=S)
MMSMT
hydrogen
is assigned to
The medium intensity band in
The IR spectra of cobalt(II),
complexes with
-1
This
ligands undergoes blue
indicates
triazole with metal ion
.
64
the
bonding
of
ring
shift
in the
nitrogen
of
In all the complexes the band m
the region 2360-2300 cm 1 due to V(SH) disappears and the other
due
to
iv(C=S)
becomes
685-675 cm 1.
weak
and
shifts
to
lower
This confirms the participation of
wave
number
-SH group in
coordination.
iii)
IR studies of MPSMT and its lanthanide(III) complexes:
The assignment of IR spectral bands of the ligand MPSMT
is described in the previous paragraph.
of MPSMT and its lanthanide(III)
VIII.
In
lanthanide (III)
The IR spectral data
complexes are given in Table
complexes,
the v (NH)
and v(sh) bands
appear at the same region as in the ligand. The position of the
band at 751 cm
1 due to v(c=S)
the
This indicates
complexes.
taken
part
in
the
of the ligand is unaffected in
that
coordination
the
sulphur
to the
atom has not
metal
disappearance of the broad weak band around 2765
intramolecular
shifting
frequency
H-bonding
to
the
azomethine
band
due to phenolic v(c-O)
from
1250
cm 1
1286 cm 1
cm
-1
nitrogen
of the
to
ion.
The
due to
and
to the
the
higher
indicates
the
coordination of phenolic oxygen of
the ligand to the metal via
deprotonation.
v(c=N) of
The
shifting of
the
ligand
from
1610 cm 1 to 1628-1647 cm 1 in the complexes
accounts for the
participation of
coordination111.
theazomethine
nitrogen
in
The broad absorption peak at 3438 cm 1 in the lanthanide (III)
65
90UBU!LUSUBJ1%
I
1
'
.
..... ......I
2500
2000
Wavenumbers (cm-1)
Fig. 6 IR spectrum of [Ni (MIIAMT)Cl
3000
(HO)
.
1500
1000
65
H
-i
-\
0
-
5-
10
15
20
25
30
35
40
i—Sfr
l-o$
55
09
aoue}}!iusuejj_%
Fij?. 7 IH sp e c tr u m
o f IP r(llP S lIT )
NO 1H O
Table VIII Important IR frequencies
Compound
Compound
V(OH)
v(OH)of
(cm 1)
V(NH)
of the ligand
V (SH)
V(C=N)
(MPSMT)
V(C = S)
and lanthanide(111)
V(C- 0)phenolic
V4
code
vi
N03
V2
of water phenolic
2765
MPSMT
3105
2306
1610
756
1250
complexes
V6
V3
V_
3
1
[La(MPSMT) NO ]H 0
2
3
2
3431
-
3036
2371
1647
751
1260
1530 1315 1025
840 725 678
B2
[Ce (MPSMT) 2NC>3 ] H20
343 1
-
3 03 6
2370
1634
751
12 82
153 0 1320 1030
899 725 680
B
[Pr(MPSMT)2N03]2H20 3431
-
2 913
2370
1647
751
12 82
1530 1315 1030
842 72 5 680
[Nd(MPSMT)2N03)2H20 3388
-
3060
2 3 80
1621
751
1282
1526 1320 1035
899 725 689
[Sm(MPSMT) NO ]3H 0 3406
2
3
2
-
2931
2370
1628
763
1282
1520 1320 1035
899 725 677
B6
[Eu(MPSMT)
NO )3H 0 3425
3
2
-
2 944
2360
1628
764
1282
1530 1320 1030
850 725 677
B
(Gd(MPSMT)2N0312H20 3438
-
2 944
2370
1634
751
1276
1520 1301 1054
825 725 678
[Tb(MPSMT)2N03]2H20 3431
-
3 036
2 3 86
1629
752
1270
1536 1320 1030
901 72 5 684
[Dy(MPSMT)2N03]2H20 33 94
-
303 6
2356
162 8
751
1270
1536 1314 1030
894 730 677
[Er(MPSMT)2N03]2 H2 0 3431
-
2930
2 3 80
1634
751
1282
1530 1320 1035
906 72 5 680
[Yb(MPSMT)2N03]2H20 3413
-
2930
2370
1634
758
1276
1530 1320 103 5
906 725 680
[Y(MPSMT)2N0312H20
-
2930
2380
1634
758
1275
153 6 1326 1030
906 725 689
B
B
B
B
B
B
B
B
3
4
5
7
8
9
10
11
12
2
343 8
66
t-54Q3
complexes indicates
the presence of water molecule(s).
This
was further confirmed by TG studies.
The nitrate in metal complexes is present either as an
ionic
species
or
coordinated
one.
Further,
if
it
is
coordinated, it may act as monodentate or bidentate ligand. The
infrared spectra contributed sufficient
information regarding
the behaviour of the NO^ group.
Nitrate
ion
can
be
bonded
to
a
metal
ion
in
three
different ways as shown below.
When nitrate ion acts as a coordinating agent,
a)
the symmetry of the ion is lowered to C
b)
all six normal modes of vibration become IR active
c)
shifts in band position occur and
d)
the degenaracy of
and
is lifted.
For uni and bidentate coordination of the nitrate ion,
the
made
symmetry remains
a detailed study
the
112
same
of
(C
the
) '
anc* Curtis
IR spectra of
with uni and bidentate nitrate ions.
splitting of the degenerate
Curt:*-S
the
have
complexes
They have found that the
vibration of
the free nitrate
ion is of the order of 100-150 cm 1 for unidentate coordination
and 190-220
cm 1
lanthanide(III)
for
bidentate
coordination.
The
present
complexes show six absorption bands near 1486,
67
1290,
1030,
860,
758
Y
coordinated
v -v
(C,^)
and
V2'
nitrate
700
v
6
group.
cm 1,
v_
3
and
The
i
v
magnitude
of
v. -v
and
are in the range of 196-209 and 58-65 cm \ respectively.
This confirms
the coordination of nitrate group
in bidentate
_ . .
113,114
fashion
Electron spin resonance spectra
The
(ESR)
fundamental
principle
of
electron
is essentially the same as that of NMR.
spin
resonance
The practical
difference arises from the fact that the magnetic moment of an
electron is substantially larger than that of a proton.
The
energy of resonance absorption is
hE = hv = gpH,
where v = Frequency of radiation
h = Plank's constant
g = Spectroscopic Splitting Factor
p = Bohr magneton
H = Magnetic field.
The ESR instruments are operated in the region of 9200
MHz with the corresponding field intensity - 3000 gauss.
to the orbital moment contribution,
68
Owing
the value of g will differ
from 2.0027.
The value of g in any arbitrary direction can be
expressed as the resultant of the tensor components q , q and
x
y
g
corresponding to the direction of the x, y and z axes.
The
z
average value (g
g
= 1/3
(g
av
)
is given by the relation.
+ g
x
+ g
y
)
z
measurements on homogeneous powder sample give g
and g
values
only as observed in the case of complexes under study.
The
position
of
g^
and
g
diphenyl
ethylene radical
values
picryl
(TCNE).
are
hydrazyl
The g
Blumberg
to
the
procedure
with
(DPPH)
and g
«
according
compared
or
resonance
tetracyano
values are calculated
1
indicated
by
peisach
and
recorded both
room
115
9„ °r
9TCNE
X H (TCNE)
H
(9tcne = 2'0027)
9
ESR
spectra of
the
a, -
complexes
1/3
<9« + 29'
were
temperature and liquid nitrogen temperature.
ESR spectra of
the polycrystalline Cu(II) complexes are shown in Fig. 8 to 11.
The g values obtained from the spectra are represented in Table
IX.
From the observed g values g(j > g > gg
69
(2.0027),
it
is
Fig.
8
ESR spectrum of [Cu<miAMT)Cl.H_0]
SCAN RANGE
Fig.
ESR spectrum of [Cu(llllAMT)Cl.Il201
in polycrystalline state at LNT
9
SCAN RANGE
FiR.
.
in polycrystalline state at RT
lo ESR spectrum of [Cu(MPSllT)Cl H^Ol
SCAN RANGE
FiR.
in polycrysta
11 ESR spectrum of
SCAN RANGE
[cudiPsimei.H oi
evident that
the unpaired electron lies predominantly in the
d^2_^2 orbital with the possibility of some dz2 character being
mixed with it because of low symmetry
In
axial
symmetry
the
g
11.6
values
are
related
by
the
,
117,118
expression
(9|j- 2)
G = -----------------
(g - 2)
-L
which measures the exchange interaction between copper centers
in
the
polycrystalline
solid.
According
value of G is greater than four,
negligible,
where
considerably
complex.
as
In
the
interaction
present
Hathway
if
the
the exchange interaction is
when the value
exchange
to
is
of
G
is
less
indicated
investigation,
all
in
than
the
four
solid
copper(II)
complexes have G values in the range 2.72 to 3.9 indicating the
interaction
of
copper
centers
which
is
also
supported
by
subnormal magnetic moment.
Metal-ligand covalency
For a planar D4h copper(II)
complex Kivelson and Neiman
showed that for ground state
vy = a . _
+ ligand terms
a 2 2
x -y
where a is the coefficient of the ground state ^x2_y2 orbital
an estimate of a 2 could be obtained using the expression:
70
Table IX ESR spectral data of copper(II)
Complex
Complex
code
RT
..... .... ....... ..........
91|
S
C6
[Cu(MMAMT)Cl.HO]
(Cu(MPAMT)Cl.HO]
9
C12
[Cu(MMSMT)]
[Cu(MPSMT)J
gj_
gav
.
-a x 10
,
in cm *
a2
2.257
(2.289)
2.110
(2 . 103)
2.159
(2.165)
2.040
2.015
{2.015)
2.023
102.8
0.385
2.7
(2.025)
(119.4)
(0 .331)
(3.1)
52 . 1
(53.6)
0 . 145
3-2
(0.164)
(3-3)
0.544
(0.480)
(3.9)
(2.047)
c
complexes in solid state
189.7
0 . 527
2 .7
(192.4)
(0.534)
(2.8)
2.216
2.073
2.134
(2.223)
(2.075)
(2.134!
2.254
2 . 065
(2 . 065)
2.123
195.9
(2.136)
(173 .0)
(2.277)
The values in parenthesis are at LNT.
71
3 .8
“2 = o 03i~+
(9«
" 2'0027)
+ 3/?
(9
-
2.0027}
+ 0.04
-L
This
relation has
metal-ligand covalency,
D4h
Here
a
been widely employed
as
measure
of
even for the complexes not possessing
2
is
the
residence
time
of
unpaired
electron on ‘copper (II) ion.
The a
range
of
2
values
0.145
to
for
the
0.544
present
complexes
indicating
fall
covalent
in
the
nature
of
copper(II) and ligand bonds.
Kivelson
and
Nieman
118
have
shown
that
the
g()
moderately sensitive function of metal ligand covalency.
ionic
environments
gMis
covalent environments it
normally 2.3
is
or
larger and
less than 2.3.
is
For
for more
So the g^
values
2.04 to 2.28 for the complexes under investigation also impute
that the complexes are covalent in nature.
Proton magnetic resonance studies
The
proton
magnetic
MPSMT and its lanthanum(III)
resonance
spectra
of
the
ligand
complex were recorded in DMSO-d
O
solvent . The chemical shift values 8 (in ppm) are given in the
Table X and spectra are presented in Fig. 12 and 13.
The protons of piperidine ring appeared as multiplet in
72
the region 8 1.98-2.40 ppm (5,
1.98,
6H, d,
CH -CH -CH ; 2.40,
2
2
2
4H, d, H^C-N-CH^). A singlet observed at 5 3.27 ppm is
methylene protons.
The presence of NH and
SH peaks indicate thiol-thione tautomerism in the
protons.
spectrum
8 6.70-7.66 ppm
The
singlet
due
to
lanthanum(III)
phenolic
peak
phenolic
complex.
oxygen
deprotonation.
to
Two singlets at § 11.16 and § 2.50 ppm are
due to NH and SH protons respectively.
multiplet at
due
in
The
(m,
at
-OH
This
4H,
8
Ar-H)
12.06
group
coordination
singlet
at
8
the
ligand
observed
the
with
observed
in
not
confirms
The
is due to aromatic
ppm
is
ligand.
in
the
involvement
the
of
metal
8.43
ppm
via
due
to
azomethine proton of the ligand has undergone down field shift
to 8 9.00 ppm in the spectrum of lanthanum(III)
confirms
deshielding as
nitrogen
of
the
a result of
azomethine
group
complex.
This
coordination through the
to
the
metal
ion.
The
resonance due to the NH proton of the ligand at 5 11.16 ppm is
unaffected
in
the
spectra
of
lanthanum(III)
complex.
This
suggests -SH group of the tautomeric form of the ligand has not
taken part in coordination.
73
'ftfc91JNI
u .c
u .s
FiR . 12
H NMR
spectru in o f
MPSIIT
0.03
14
13
12
Fiff.
11
13
10
0.05
a
~T~
0.05
-0.00
0.10
H NMR spectrum of
1
PULSE SEQUENCE
Relax, delay 1.000 sec
Pulse 54.0 degrees
Acq. time 1.500 sec
Width 4000.0 Hz
64 repetitions
OBSERVE
HI, 199.9760221 KHz
DATA PROCESSING
Line broadening 0.1 Hz
FT size 16384
Total time 2 minutes
------
flC
ASP1
23/6/98
Solvent: dmso
Ambient temperature
GEMINI-200 M c1ba"
[La(lIPSllT)
0.16
NO 1H_0
0.08
0.19
0.00
v
*
.
0.24
A
£
f
CL
Q.
Table
X
1HNMR
spectral
data
of
ligand
MPSMT
and
its
Lanthanum(III) complex 5 in ppm
Ligand
Complex
Assignements
1.98-2.40m
1.98-2.40m
-6H piperidine ring protons
6.70-7.66m
6.70-7.66m
-4H aromatic protons
3.27s
3.27s
-CH - proton
2.50s
2.50s
-SH- proton
8.43s
9.00s
-N=CH- azomethine proton
11.16s
11.16s
-NH (hydrazine-NH) proton
phenolic -OH
12.06s
s=singlet
m=multiplet
74
proton
Thermal studies
There are various thermal analysis techniques currently
employed,
which
thermal
include
analysis
differential
analysis
(DTA),
scanning
(EGA).
thermogravimetry
derivative
calorimetry
(TG),
differential
thermogravimetry
(DSC)
and
(DTG),
evolved
These techniques provide valuable
gas
information
about a given substance.
Of
the
various
thermal
analysis
techniques,
the
most
widely used techniques are TG and DTA. Thermogravimetry (TG) is
the technique, in which the change in mass of a substance in an
environment heated or cooled at a controlled rate is recorded
as a function of time or temperature. Such a record is called a
thermogravimetric
or
TG
curve.
One
of
the
most
important
applications of TG technique is to know the thermal stability
of
a given substance with a view to ascertain its weighable
form in conventional gravimetric method.
factors
that
affect
The most
the pattern of TG curve are
important
the heating
rate and the sample size.
In
the
present
investigations,
TG
measurements
of
cobalt(II), nickel(II), copper(II) complexes of MMAMT and MPAMT
and lanthanide(III) complexes of MPSMT have been carried out in
static
air,
using
limiting
75
temperature
of
a
900 C
and heating
rate of
10 C/min.
weight
loss
as
The TG curves were analysed as percentage
a
function
of
temperature.
The
number
of
decomposition steps were identified using a derivative of TG
curves. Typical thermogravimetric curves are shown in the Fig.
14 to 17.
The
steps.
of
MMAMT
and
The first step at 35-310°C,
between
water
complexes
16.20-20.10%,
and
chloride
decomposition
the
MPAMT
to
molecule.
In
is
lost
loss
of one
stable
two
the
between
coordinated
second
the
step
of
temperature
°
of
O
211-850 C.
plateau
in
with a weight loss ranging
corresponds
ligand
decomposes
is
There is no further weight loss beyond 850 C and a
obtained
metal
calculated
oxide
form TG
which
corresponds
(Table
studies
to
the
formation
XI).
The
percentage
agrees
well
with
the
of
of
metal
theoretical
results within the experimental errors.
In
temperature
case
of
of
lanthanide(III)
decomposition,
the
complexes
of
MPSMT
the
pyrolysed
products,
the
percentage weight loss of the ligands, and the percent residue
are
given
in
Table
XII.
The
lanthanum(III)
e
weight loss of 2.03% at 80-120 C
complex
which indicates
of one uncoordinated water molecule in the lattice
the second stage,
the weight loss of 81.48%
76
shows
a
the presence
(2.11%).
In
(calcd.81.59%)
in
Table XI
Thermogravimetric data of Co(XX),Ni(XX) and Cu {11) complexes of MMAMT and MPAMT
Complex
Temperature
Process
Product
o
range/ C
(CoIMMAMT)Cl.2H^0]
Dehydration &
Decomposition
Weight %
Calc. Expt.
No. of
moles
H2 0 &
40 - 280
Cl
20.74
20.04
1
62.11
61.74
1
20.78
21.28
62.74
62 . 83
16.16
16.70
65.25
65.84
20.87
19.74
62.18
61.41
19.95
20.10
61.74
62.41
16.76
16.04
64.75
63.84
of coordination
sphere (L, Cl)
(NilMMAMT)Cl.2H^O}
281 - 640
Dehydration &
Decomposition
H 0 &
2
2
35 - 250
Cl
1
of coordination
sphere (L, Cl)
(CuIMMAMT)Cl.H20J
251 - 580
HO &
Dehydration &
Decomposition
1
2
40 - 262
Cl
1
of coordination
sphere (L, Cl)
(CoIMPAMT)Cl.H20)
263 - 688
H 0 &
Dehydration &
Decomposition
2
40 - 230
Cl
of coordination
sphere (L, Cl)
(Ni< MPAMT)Cl.HO]
231 - 850
H20 &
Dehydration &
Decomposition
50 - 220
Cl
of coordination
sphere (L, Cl)
[CuiMPAMT)Cl.HO]
221 - 550
H 0 &
Dehydration &
Decomposition
1
2
70 - 310
Cl
of coordination
sphere (L, Cl)
77
311 - 720
1
Table XII
Thermogravimetric data of lanthanum!111) , neodymium(111) and dysprosiumi111) complexes
Complex
Process
Decomposition
Temperature
range (°C)
[La(PSMT)2no3]h2°
Dehydration
Decomposition
80 - 120
121 - 540
of coordination
Decomposition
Product
H2°
2
PSMT
Sc
Weight loss
No.of
Obs.
Calc.
moles
2.11
2.03
1
01.59
81.48
2
N°3
1
sphere {2 PSMT,NO )
[Nd(PSMT)2N0312H20
Dehydration &
55 - 196
H2 0
Sc
10.86
10.78
2
Decomposition
of coordination
NO
1
3
sphere {NO )
of Decomposition
197 - 300
PSMT
35.57
35-38
1
PSMT
35.57
34-64
1
9 .02
9.23
coordination
sphere EPSMT)
Decomposition of
coordination
sphere (PSMT)
[Dy (PSMT) 2N031 21^0
Dehydration &
40 - 210
H2°
Decomposition of
no3
coordination
1
sphere (NO )
Decomposition of
211 - 295
PSMT
3 5.55
3 5.18
1
PSMT
35.55
3 5.43
1
coordination
sphere (PSMT)
Decomposition of
coordination
sphere {PSMT)
78
*TM
F i* . 1 4 T .G . c u r v e o f [M iO M A M D C l.
O t^ l
pf
m
N*
Tem p.
06
C
O
O
880J
F i« . 1 5 T .G . c u r v e o f C C u O U IA M D C l.^ O l
Tem p.
Temp.
F i r . 16 T.G . c u rv e o f [La(lIPS»IT> 2 N03 lH 20
PlbAKU CAT. NO 9004CG
ssoi
F iR . 17 T .G . c u rv e o f
IH d d lP S lfD ^ U ^ O
Temp.
o
the
temperature
range
121-540 C
indicates
nitrate and two ligand molecules. The
the
loss of one
plateau obtained beyond
O
540 C
indicates
the
formation
complexes of neodymium(III)
of
stable
La O .
2 3
and dysprosium(III)
In
the
the first step
O
of decomposition occurs between 55-196 and 40-210 C with weight
loss of 10.78 and 9.23%,
respectively. This corresponds to the
loss of two uncoordinated water and nitrate molecule. In second
O
O
step, decomposition occurs between 197-300 C and 211-295 C, and
this
decomposition
accounts
for
the
loss
of
one
ligand
O
molecule. In third step, decomposition occurs between 301-626 C
O
and 296-690 C,
another
and this decomposition accounts for the loss of
ligand
(Table XII)
molecule.
The
percentage
of
metal
obtained
by this method is in good agreement with that of
the EDTA titration method followed.
kinetic
studies
of
cobalt(II),
nickel(II)
and
copper(II)
complexes with MMAMT and MPAMT
The thermograms obtained during TG scans were analysed
to
give
the
temperature.
(temperature
c
percentage
weight
Tq (temperature of
for
10%
weight
loss
as
a
function
of
onset of decomposition), T^Q
loss)
and
T
max
(temperature
of
maximum weight loss) are the main criteria to indicate the heat
79
stability of the complexes.
and T
The higher the values of Tq,
T
, the higher the heat stability,
max
Broido's
method
was
used
to
evaluate
the
kinetic
parameters from the TG curve. Using Broido's method, plots of
In (In 1/y) vs l/T
(where y is the fraction not yet decomposed)
for different stages of the thermal degradation process of the
complexes were made
19.
Fig.
(Table XIII)
and are shown in Figs.
18 and
18 is first step of the degradation and Fig.
19 the
second step of degradation.
In order to determine the thermal
parameters T , T1Q/
Tmax'
stability trend,
activati°n energy
(Ea)
the
and frequency
factor (In A), were evaluated and are given in Table XIV . The
thermodynamic
parameters,
#
(AG ) ,
enthalpy
entropy
#
(As )
and
free energy (AG ) of activation, were calculated using standard
equations and the values are given in Table XV.
11
The
indicates
possible
ASff
a
values
more
through
have
ordered
the
found
to
activated
chemisorption
decomposition products 119 ' 120 .
be
state
of
negative,
which
oxygen
than that for the first stage which
80
might
and
be
other
The energy of activation values
for the second stage of decomposition were found to
decomposition of second stage
which
is
be
higher
indicates that the rate of
lower
than
that
of
first
lr<lnl/^
to
o
a
to
—
t
H
n
Indnl/Y)
M
aw*
to
O to
O
H — <N
a
>
Fig. 19 Plots of ln(ln 1/y) vs. 1/T for the second degradation
process of (A) [CoCMMAMDCl. (H20>21; (B) [Ni(10IAMT)Cl. <H20)21
(C) [Cu(I0IAMT)C1.H201;
(D) [Co(MPAMT)C1 . (H20>21;
(E) [Ni(10IAMT)Cl.(H20)2l;
(F) lCu«OiAliT)Cl.H Ol
Table
XIII
Kinetics
of
decomposition
studies
on
cobalt(II),
nickel(II) and copper(II) complexes of 3-substituted4-amino-5-mercpto-l,2,4-triazole
Complex
code
C1
C2
Stage
Complex
[Co(MMAMT)Cl.2H20]
[Ni(MMAMT)Cl.2H0]
81
In(In 1/y)
1/TxlO3
-0.7320
3.1948
-0.7260
-0.7229
-0.7135
-0.7038
-0.7005
-0.6972
-0.6729
3.0487
3.0030
2.9154
2.6809
2.5839
2.4813
2.0202
-0.6185
1.7636
-0.6100
-0.6013
-0.5923
-0.5831
-0.5737
-0.5640
-0.5541
1.7513
1.7331
1.7211
1.7094
1.6891
1.6778
1.6638
-0.7198
2.9154
-0.7136
-0.7071
-0.7005
-0.6620
-0.6583
-0.6507
-0.6429
2.8328
2.7548
2.6954
2.2573
2.1978
2.1141
2.0618
-0.5541
1.7574
-0.5462
-0.5225
-0.5200
-0.4999
-0.4881
-0.4366
1.7391
1.7094
1.6920
1.6722
1.6583
1.6051
c3
[Cu{MMAMT)Cl.H O]
I
II
C
4
[Co(MPAMT)C1.2H Oj
I
II
C
[Ni(MPAMT)Cl.2H 0]
I
-0.7198
3.0487
-0.7135
-0.7071
-0.7005
-0.6940
2.9154
2.8328
2.7548
2.2809
-0.6269
1.7921
-0.5923
-0.5541
-0.5334
-0.4501
-0.4336
1.7513
1.7035
1.6778
1.5797
1.5552
-0.7320
3.1545
-0.7260
-0.7198
-0.7071
-0.7005
-0.6964
-0.6870
3.0581
3.003
2.8818
2.8328
2.7855
2.5773
-0.4632
1.6583
-0.4366
-0.4081
-0.3774
-0.3442
-0.2889
-0.2475
1.6240
1.6103
1.5898
1.5673
1.5313
1.5037
-0.7769
3.2467
-0.7608
-0.7552
-0.7496
-0.7380
-0.7320
2.9498
2.8673
2.7855
2.5773
2.4691
-0.6507
1.7452
-0.6350
-0.6185
-0.6013
-0.5831
-0.4226
-0.3612
1.7301
1.7211
1.7152
1.7094
1.6051
1.5600
5
82
C
[Cu(MPAMT)Cl.HO]
b
I
-0.7608
3.0030
-0.7580
-0.7562
-0.7512
-0.7496
2.8328
2.6109
2.2321
2.1052
-0.7440
1.9685
-0.6801
-0.6657
-0.6507
-0.6350
-0.6185
-0.6013
-0.5831
-0.5640
1.7094
1.6977
1.6863
1.6806
1.6750
1.6694
1.6638
1.6482
2
II
83
Table
XIV
Data
characteristics,
obtained
TG
analysis
:temperature
activation energies and frequency factors
of decomposition process.
O
Complex
[Co(MMAMT)Cl.2H 0]
T / c
40
T
/ °C
10'
210
T
/°C
max
640
Process
I
II
[Ni(MMAMT)Cl.2H20]
35
125
580
I
II
[Cu(MMAMT)Cl.H 0]
40
220
688
I
II
[Co(MPAMT)Cl,2H20]
98
40
850
I
II
[Ni(MPAMT)Cl.2H20]
50
220
580
I
II
[Cu(MPAMT)Cl.HO]
70
285
720
I
II
84
Ea/
In A/
•1
. -1
kJ mol
mm
0.95
4.34
12.44
9.17
1.66
5.14
12.12
9.25
1.53
5.02
14.67
9.90
2.17
5.60
27.52
13.02
1.14
4.56
30.63
5.91
0.22
2.60
44.67
16.94
Table XV Thermogravimetric parameters for the
thermaldegradation of the complexes
Complex
[Co(MMAMT)Cl.2H 0]
[Ni(MMAMT)Cl.2H 0]
[Cu(MMAMT)Cl.HO]
[Co(MPAMT)Cl.2H20]
[Ni(MPAMT)Cl.2H20]
[Cu(MPAMT)Cl.HO]
Process
#
aG
kJ mol ^
#
AH
J K ^ mol ^
#
AS
kJ mol 1
I
-2.26
-150.90
56.13
II
7.18
-126.82
87.46
I
-1.35
-149.41
50.67
II
7.26
-126.77
81.42
I
-1.48
-149.69
52.85
II
9.72
-122.89
82.96
I
-0.76
-147.99
51.47
II
22.36
-100.63
84.85
I
-1.75
-151.57
51.47
II
25.45
-87.73
80.11
I
-3.50
-152.25
64.70
II
39.67
-73.85
84.06
85
stage. This may be attributed to the structural rigidity of the
ligand,
MMAMT/MPAMT,
requires more
as
energy for
compared
its
any compositional change.
with
H^O
and
rearrangement before
Further,
it
Cl,
which
undergoing
is generally observed
that step wise formation constants decrease with an increase in
the number of ligands attached to the metal ion
121
.
During the
decomposition reactions a reverse effect may occur.
Hence the
rate of removal of the remaining ligands will be smaller after
the expulsion of one or two ligands
122
The values of the entropy for all degradation steps of
all
the
complexes are negative.
are negative for the first
The enthalpies
step and positive
of activation
for the second.
However, the negative values of the entropies of activation are
compensated by the values of the enthalpies of activation
leading to almost the same values
(50.67-87.46 k J mol
)
123
for
the free energies of activation.
kinetic studies of lanthanide(III) complexes of MPSMT
For different stages of the thermal degradation process
of the lanthanide(III)
complexes were made
(Table XVI)
and are
shown in Figs. 20, 21 and 22. Fig. 20 is for first step of the
degradation,
Fig. 21 is for second step of the degradation and
Fig. 22 for the third step.
86
In order to determine the thermal
248
244
250
.1
256
U2
2.98
-3 -1
TX10 K
Fig. 20 Plots of ln(ln 1/y) vs.
1/T for the first degradation
process of (A) [Nd(MPSMT) NO 12H O; (B) [Dy(MPSMT) NO 12H O
2
o
2
2
O
2
(C) [La(MPSMT) NO 1H O
/ J Z
Fig. 21 Plots of ln(ln 1/y) vs.
1/T for the second degradation
process of (A) [Dy(MPSMT) NO ]2H O; (B) [La(MPSMT) NO ]H O;
2 3
2
2 3 2
(C) [Nd<MPSMT> NO 12H O
2
O
Z
0.06
o
9
ft
M*
a
P
Q
.
t
o
to
1
p
c
t
n
2
O
CO
a
a
rt
M.
9*
C
D
D
*
ft
*
1
t
o
a
t
o
0
<
a
£
o
H
a
CO
cu
a
2
wT>
«
CM
CM
H
a
w
0
.
wa>1
A
O
m
m
<
o
o
0
u
a
CO
v
N—
9
a
o
o
ft
w
Uh
to
to
tnflnSY)
-
stability
such as
trend
T ,
o
T
of
10
,
lanthanide(III)
T
max
,
complexes
activation energy
the
(Ea)
parameters
and frequency
^
J
factor (In A), were evaluated and are given in Table XVII. The
thermodynamic
parameters,
(AH a ) ,
enthalpy
entropy
#
(ASff)
and
free energy (AG ) of activation, were calculated and the values
are given in Table XVIII.
The As
indicates
possible
a
#
values
have been found
ordered
more
through
the
activated
chemisorption
to
be
negative,
which
state
of
oxygen
which
might
and
be
other
decomposition products. The energy of activation values for the
second stage of decomposition were found to be higher than that
for
the
first
decomposition
of
stage
second
stage. But finally,
This
may
ligand.
NO^
be
indicates
stage
is
lower
that
the
than
that
rate
of
of
first
third stage decomposition becoming faster.
attributed
to
In the first stage,
might
XVII.
be
which
the
structural
rigidity
of
the
the simple molecules like H20 and
eliminated which require
minimum
energy
(Table
In the second stage, the structure of the ligand (MPSMT)
is complicated which requires more energy for its rearrangement
before undergoing any compositional change. However,
energy of
activation of last stage is much lower than expected because in
this another molecule of MPSMT is removed. This may be
87
due
to
Table XVI
complexes
Kinetics of decomposition studies on lanthanide(III)
of
3-N-Methylpipiridino-4-salicylideneamino-5-
mercpto-1,2,4-triazole
Complex
code
Complex
Stage
[La(MPSMT) NO ]H 0
I
II
B
4
[Nd(MPSMT) 2NC>3] 2H20
I
II
III
88
In(In l/y)
1/TxlO3
-0.7380
2.8380
-0.7356
-0.7320
-0.7005
-0.6938
-0.6972
-0.6729
-0.2475
-0.2253
-0.1511
2.6953
2.4813
1.9305
1.9120
1.9013
1.8902
1.7331
1.7182
1.6891
-0.6185
2.9154
-0.6143
-0.6100
-0.5968
-0.5923
-0.5878
-0.5785
2.8735
2.7932
2.5510
2.4875
2.3696
2.1643
-0.5541
2.0080
-0.5439
-0.4081
-0.3931
-0.3774
1.9685
1.8348
1.8248
1.8083
-0.1772
1.6528
-0.1511
-0.1234
-0.0940
-0.0627
1.6313
1.6051
1.5797
1.5455
-0.0462
1.5267
Table XVII Data obtained TG analysis : temperature
characteristics, activation energies and
frequency factors of decomposition process.
Complex
T / C
[La(MPSMT)2N03]H20
80
T
/°C
T
/°C
10
max
235
540
Ea/
In A/
, -1
. -1
kJ mol
mm
Process
0.33
3.06
39.88
16.54
1.32
4.86
20.29
11.86
III
1.91
5.68
I
0.76
4.19
35.72
15.72
3.75
23.13
I
II
[Nd(MPSMT) NO ]2H 0
55
185
630
I
II
[Dy(MPSMT)2N03]2H20
40
130
690
II
III
89
Table XVIII Thermogravimetric parameters for the thermal
degradation of the complexes
Complex
Process
4a*-i
kJ mol
[La(MPSMT)2n°3]H2°
[Nd(MPSMT)2N03]2H20
mol
I
-2.67
.-153.86
27.52
II
35.62
-71.35
107.74
I
-1.83
-151.72
45.43
II
31.47
-78.85
52.67
3.38
-157.81
105.17
I
-2.18
-148.00
60.29
II
15.75
-108.81
43.54
III
-3.26
-131.90
78.90
III
[Dy (MPSMT) 2NC>3] 2H20
<
J K
AG#
kJ mol ^
90
catalytic activity of metal complexes in the oxidation of the
ligand and other decomposition products in the third stage. The
catalytic
activity
of
lanthanum(III)
complex
(Table
XVI)
is
more pronouced because the decomposition completes only in two
stages.
X-ray (powder) diffraction studies
The
X-ray
[Cu(MPAMT).Cl(H^O)]
Phillips
(powder)
were
diffraction
recorded
diffractometer
pattern
(in
for
cellulose
using CuKa radiation
complex
phase)
on
(A. = 1.5418 A°)
O
with angular range of 10-70
to know the internal structure of
the complexes. The diffractogram is reproduced in Fig. 23.
The
20 values for prominent peaks have been indexed and their Q
values have been compared with the Q values calculated
XIX) .
The
tetragonal
observed
values
system with a
=
are
in
°
27.735A ,
c
good
=
(Table
agreement
11.658A
3
and
with
cell
volume = 8967.68A .
The diffractogram of
[Dy(MPSMT)
NO ].2H 0 is recorded
M
4W
o
with CuKa X-ray tube in the range of 10-70 .
The 20
and
'd'
spacings for the prominent peaks are listed in Table XX and are
indexed
by
trial
and
presented in Fig. 24.
error
method.
The
diffractogram
is
The observed values for the complex are
91
T
O
Lf>
30
D if f r a c tio n a n g le ( 2 © )
^^
20
F iR . 2 3 D if f r a c to R r a m o f lC u(liP A M T )C l(H 2 0 )
40
—
iU_
]
10
F ig . 24 D if f r a c to g r a m o f
ID y(M PSllT)
D if f r a c t io n a n g le ( 2 6 )
«
«5
4
NO 12H O
Table XIX
Peak
X-ray (powder)
20
d K
obs .
diffraction data of
d
,
cal .
[Cu(MPAMT)Cl.H^O]
0 K
obs .
Qcal.
r(Q)
Relative
h
k
1
Intensity
No .
in %
1
15.2
5.8288
5.829
0.0294
0.0294
0.0002
70
002 ,
141
2
15.5
5.7170
5.704
0.0306
0.0307
0.0002
60
102 ,
331
3
16.0
5.539
5.547
0.0326
0 .0325
0.0002
50
112 ,
500 ,
34
4
18.55
4.783
4.757
0 . 0437
0 .0442
0.0002
100
350
5
22.05
4.031
4.018
0 .0615
0.0619
0 . 0003
75
502
6
2 3.75
3.746
3 .742
0 . 0713
0.0714
0 . 0003
85
2 0 3,
4 4 2,
70
7
26.35
3.382
3.390
0.0874
0.0870
0.0003
55
403 ,
4 13,
36
8
26.75
3.332
3.340
0 . 0900
0 . 0896
0 .0003
70
3 3 3.
801
9
31.35
2.853
2.852
0 . 122 8
0 . 1229
0.0004
50
224 ,
6 6 2,
E8
10
31.60
2.831
2.832
0.1247
0 . 1247
0-0004
75
2 14,
363 ,
38
11
32 . 60
2 . 746
2.746
0.1326
0.1326
0 .0004
65
482 ,
491,
10
12
38.90
2.315
2.315
0.1866
0 . 1866
0 . 0005
55
105 ,
115,
46
13
43.85
2.065
2.064
0.2346
0 . 2347
0.0005
48
2 65 ,
5 84,
39
14
49.75
1 .8327
1.834
0 .2977
0 . 2974
0 . 0006
45
506 ,
346 ,
51
For Tetragonal system
a = 2 7.7 3 5 A ’
C * 11.658A'
Cell volume = 8967.68A'
92
Table XX
Peak
X-ray
20
(powder)
d .
obs .
diffraction data of
dcal .
[DytMPSMT)^ NO^] 311^0
Qcal .
Q .
obs .
c Tq )
No .
Relative
h
k
1
Intensity
in %
1
15.25
5.810
5.813
0.0296
0.0296
0.0002
75
005 ,
2
16.05
5 . 522
5 .573
0 .0328
0.0322
0 . 0002
21
113
3
17.80
4 . 982 8
4 . 982
0.0403
0 . 0403
0.0002
25
105 ,
114
4
20.60
4.3115
4.325
0 . 0538
0 . 053 5
0.0003
15
106 ,
203,
5
2 1.40
4.152
4.152
0.0580
0.0580
0.0003
40
007 ,
212
6
22.60
3.934
3.948
0 . 0646
0 . 0642
0.0003
29
116 ,
213
7
2 6.80
3.3265
3.327
0 . 0904
0 . 0 903
0.0003
100
8
30.45
2.9355
2.946
0 . 1160
0.1152
0.0004
20
22 5 ,
9
41.85
2.1585
2.158
0 . 2146
0 .2147
0.0005
19
3 0 10 ,
10
46.00
1.973
1 . 974
0.2569
0 . 2 566
0.0005
18
246 ,
Fcr Tetragonal system
a = 9.667A
c = 29.064A
Cell volume = 2716.05A*
93
104
21
222
304
238 ,
4 18
o
in good
agreement with a tetragonal system with a = 9.667A , c
= 29.064A
o
°
and cell volume = 2716.05A .
Based
on
the
above
studies,
the
following
structures
could be proposed for the complexes under study,
i) Structures of cobalt(II), nickel(II) and copper(II)
complexes of MMAMT and MPAMT
N---N
-N
NN
AA As
i
, /C'
H2N—►M
fcXOH2
H2O/tN'0H2
N---N
N---N
f1
h2n
sA
J
I
s
t
Cw*— H2N
M
N---N
r
H2n—►Cu
M = Co, Ni
ii) Structures of cobalt(II), nickel(II) and copper(II)
complexes of MMSMT and MPSMT
N-N
M = Co, Ni
94
iii) Structures of Lanthanide(III) complexes of MPSMT
Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Yb, Y n = 1-3
SUMMARY AND CONCLUSION
Twelve
copper(II)
new
with
synthesised
complexes
MMAMT,
and
MPAMT,
characterised
analysis,
molar conductance,
ESR,
thermal
and
stoichiometry
complexes
with
of
studies.
for
the
cobalt(II),
MMSMT
on
and
the
MPSMT
basis
magnetic moment,
The
cobalt(II),
magnetic
analytical
suggest that cobalt(II), nickel(II)
and
have
of
and
suggest
been
IR,
1:1
copper(II)
electronic
and copper(II)
and
elemental
electronic,
data
nickel(II)
moment
nickel(II)
spectra
with MMAMT,
MPAMT complexes are polymeric with octahedral geometry. The IR
spectral studies suggest that MMAMT and MPAMT act as monobasic
bidentate ligand utilising the amino nitrogen atom and mercapto
sulphur atom for bonding.
95
The triazole ring nitrogen acts as a
coordinating
site
product.
The
[Cu(MPAMT).Cl
leading
X-ray
(H^O) ]
to
the
formation
(powder)
complex
of
a
diffraction
is
in
good
polymeric
pattern
agreement
of
with
°
tetragonal
system with
a
=
27.735A ,
c
=
11.658A
and
cell
O
volume = 8967.68A .
Based
cobalt(II),
MPSMT,
on
magnetic
nickel(II)
and
electronic
and copper(II)
spectral
complexes
studies
of
MMSMT and
octahedral geometry is suggested for the cobalt(II)
nickel(II)
complexes
complexes.
The
MPSMT
as
act
IR
and
spectral
dibasic
oxygen atom for bonding.
oxobridge
studies
tridentate
azomethine nitrogen atom,
of the copper(II)
tetrahedral
mercapto
geometry
for
suggest
that
ligands
sulphur
of
and
copper(II)
MMSMT
utilising
and
the
atom and phenolic
The low magnetic moments and IR data
complexes suggest that these complexes have
structure;
the
electronic
spectra
imply
that
the
copper(II) has coordination number four in these complexes.
Fourteen new complexes of lanthanide(III)
nitrates with
MPSMT have been synthesised and characterised on the basis of
elemental
analysis,
electronic,
IR,
Analytical,
thermal
general formula
NMR,
molar
conductance,
thermal
and
[Ln(MPSMT)
96
molar
and
X-ray
magnetic
moment,
diffraction
studies.
conductance
data
suggest
the
NO ],nH 0 for these complexes. The
observed
slight
magnetic
of
lanthanide(III)
deviation from the Hunds values
values.
as
complexes
well
show
as Van Vleck
This indicates little participation of 4f electrons in
bond formation.
MPSMT
moments
acts
a
The IR and NMR spectral studies suggest that
as
monobasic
bidentate
ligand
utilising
the
azomethine nitrogen atom and phenolic oxygen atom for bonding.
Sulphur
atom has
lanthanide (III)
not
taken part
ion.
The
IR
in
the
spectral
coordination
and molar
to
the
conductance
data suggest that nitrate ion is coordinated bidentately to the
lanthanide
ion.
[Dy (MPSMT)
The
X-ray
N03].2H20
(powder)
complex
is
diffraction
in
good
pattern
agreement
®
tetragonal
system
with
a
=
9.667A ,
of
with
0
c
=
29.064A
and
cell
O
volume = 2716.05A .
PUBLICATIONS
1) The part of this chapter has been published under the title
"Thermal and spectral studies of 3-N-methylmorpholino-4amino-5-mercapto-l,2,4-triazole and 3-N-methylpiperidino-4amino-5-mercapto-l,2,4-triazole
complexes
of
cobalt(II),
nickel(II) and copper(II)" in the journal Thermochimica Acta
4545, 1-7 1998.
97
2) The part of this chapter has been sent for publication under
the title "Synthetic, spectral, thermal and biological
studies of 3-N-methylmorpholino-4-salicylideneamino-5mercapto-1,2,4-triazole and 3-N-methylpiperidino-4salicylideneamino-5-mercapto-l,2,4-triazole complexes of
cobalt(II), nickel(II) and copper(II)" in the journal
"Transition metal Chemistry" 1998.
3) The part of this chapter has been published under the title
"synthetic, spectral, thermal and biological studies of
lanthanide(III) complexes with a Schiff base derived from
3-N-methylpiperidino-4-salicylideneamino-5-mercapto-l,2,4triazole" in the journal "Synthesis Reactivity Inorganic and
Metal-Organic Chemistry" 29,
98
(3) 1999.