Full text of DOI:10.1163/156856700X00471

FORMATION
COMPLEX
OF
SPECIES
NEW
MONOMERIC
Pd(III)
WITH
8-AMINOQUINOLINE
M.
NICHKOVA and M.
MITEWA
J. Bourchier
1126
av.,
BULGARIA
Sofia,
I,
Department of Chemistry,Universityof Sofia,
Received28 June
11
November 1999
1999;
accepted
means of EPR and
methods
and
3 new
Pd(III)
the formation of
Abstract--By
is
magnetochemical
complex
(aqueous
are
also
from the reaction
in
basic
of PdCl42-
species
or
proved resulting
8-aminoquinoline(8-AQ)
medium. Elemental
IR
the
data for
complexes
visible and
aqueous-methanolic)
analysis,
obtained.
In
the course of our
on formation and stabilization of
intermediate
systematic study
we have
that in
and
basic-water medium and
Pt(III)
species
already proven
and
of
are
oxidized to
and
presence
oxygen (aerobic conditions) Pt(II)
The latter
Pd(II)
being
Pt(III)
rather
in
unstable
Pd(III) respectively [1-7].
compounds
general
can be stabilized either
with
transients,
as
through complexation
proper bridging ligands
chelation with N-
mixed-valent
or
(Platinum Blues)
it can be
oligomeric
species
[1,2]
through
Therefore
that
expected
[3-7].
8-aminoquinoline
complexation
in
(8-AQ)
are
containing ligands
also will be able to stabilize
At the same time its
Pd(III).
properties
Only complexes
in acidic solution are known
its
to
water.
due most
studied,
insolubility
likely
scarcely
relatively
of some
transition
metal ions obtained
and
platinum group
to now
up
[8-13].
In the
the reaction
the results obtained
and
of PdCl4z-
present paper
basic medium
regarding
in
and
basic-methanolic medium
in
(CH30H
8-AQ
+
12)
(pH >
strongly
are
KOH)
reported.
'
EXPERIMENTAL
Synthesis of the Complexes
ml
KOH
1. 0.0324
dissolved in 10
8-AQ
(0.225 mMol)
g
=
The
1 :5).
of
pH
x 10-z
solution
is added to 1.00 ml
of PdCl42-
12-13
(M:L
(5
M)
(pH -12)
mixture is
KOH solution. Dark blue-violet
the
to
pH
reaction
residue is formed
chloroform and water and dried
by adding
adjusted
immediately,
washed
off,
The
with
data
which was filtered
for 2 weeks above
repeatedly
elemental
P401o.
analysis

484
in
1.
in
is soluble
are shown
Table
The
acetonitrile
(An)
and
CH30H, CHC13,
complex
(DMSO).
[Pd(8-AQ-H)2CIleCH30H
ml
dimethylsulfoxide
2.
0.100
dissolved in 10.0 ml
is
CH30H
8-AQ
g
x
mixed with 7.0
water solution
and methanolic solution
M),
of
of PdC142-
(5
ammonium
=
is
added
to
12
[(CH3)4N]+(OH)
tetramethyl
value)
hydroxide
dark
up
(uncorrected
The
blue residue formed is filtered
washed
with
repeatedly
off,
1:2).
(M:L
2
water and chloroform and dried for weeks above
The
is soluble in
complex
P401o.
DMSO.
in
The elemental
data are shown
3. 0.100
Table 1.
analysis
in
dissolved
10.0 ml
is
CH30H
8-AQ
g
x 10-2
[Pd(8-AQ_H)20H]eCH30H
with 7.0 ml water solution
and water solution of KOH is
M)
The dark blue residue formed is
mixed
added
filtered
of PdC142-
(5
=
to
(uncorrected value) (M:L
1:2).
up
off,
The
pH - 1 3
washed
with chloroform and water and dried for 2 weeks above
repeatedly
is soluble in DMSO.
P401o.
complex
The elemental
data are shown in Table 1.
analysis
Materials and
The
Apparatus
were used as
grade.
from Aldrich.
purchased
and
8-aminoquinoline
reagents (NH4)2PdC14
and solvents used were of AR
All
other
reagents
and IR
were recorded on
The electronic
spectra (KBr disks)
spectrometers
EPR
and "Perkin-Elmer
B-ER
UV-Vis"
983"
420"
The
respectively.
"Specord
(Carl-Zeiss-Jena)
on X-band
in
"Bruker
the
were taken
spectrometer
temperature range
spectra
K.
The
to
130-300
measurements were
in
performed
argon atmosphere
after
magnetochemical
The Pd content was determined
method.
gravimetrically
Faraday's
according
calcination at
the
with conc.
and
800 °C
to constant
up
treatment of
H2S04
samples
weight.
RESULTS AND DISCUSSION
reaction
was studied at different
with
The
of
conditions,
data obtained show that
PdCl42-
8-AQ
complexation
The
the nature of the reaction medium.
experimental
in
varying
both
the
of the reaction a
redox
in
basic and methanolic basic media
with the
course
aqueous
in
formation of
resulting
Pd(III)
proceeds together
complexation
process
species.
results were obtained in the course
interaction with some
Similar
of PdC14 2-
in
ligands
medium
[3-6].
basic
amide-containing
both
the EPR and
of
is
proven
are
The
formation
by
and EPR
Pd(III) complexes
methods. All three
active. The
complexes
paramagnetic
magnetochemical

485

486
are close to the theoretical one
for one
The
NB)
(1.73
lJefIvalues (Table 1)
corresponding
electron thus
configuration.
are in
suggesting low-spin
The EPR data obtained
unpaired
with this
(Table 2)
agreement
for
low-spin Pd(III) complexes [14,15].
assumption.
The
are
observed
complexes
typical
g-values
almost
the realization of
thus
1 and 3 are
nearly isotropic spectra,
indicating
This fact
showing
structure
be
explained assuming
trans-configuration.
might
regular
octahedral
e.g.
coordination,
be
solvent
OH- and
the 5 thand 6?' sites
being occupied by
which contains Cl-
in its coordination
which shows
As it can
molecule.
2,
EPR
expected complex
a
exhibits an
(Table 2)
anisotropic 3-component
spectrum
most
sphere,
strong
octahedral
the
deviation from
structure,
likely cis-configuration.
regular
2
Table
EPR
data.
spectral
+
+
= 1/3
(gx
gy
the relation
'Calculated
gz).
according
gi
data
visible
the
is
of
The formation
spectral
supported by
Pd(III) complexes
520 nm
bands at 380 and
weak
two new
of the
also. In the
are
(Table 1)
complexes
to d-d transitions.
be
spectra
ascribed
for 1-3 can
data the
the basis of these
On
following
observed,
structures
proposed:

487

488
IR
The
in
data
obtained
are
indicative of
coordination
a
(Table 3)
of deprotonated
of
the 3450-3200 crri
of the
intense
bands
ligand:
ascribed
range
and
ligand
NH2
spectrum
vibrations
one band
couple
to the
of the
are
while in
vibration)
the
is
symmetric
complexes
asymmetric
observed,
to NH
in the same
spectra
range only
(due
present.
At the same time in the
in
of the
broad
due to
bands,
spectra
complexes very
OH-,
- OH and
are observed. The
of a
presence
molecule
H20
engaged
CH30H
H-bonding
in 2 and 3 is also
existence of two new
in
the
bands
3000-2900 crri
supported by
CH3-vibrations.
all these
range
ascribed to
Summarizing
basic medium octahedral
it
data can be
concluded that
are formed
and
PdCl42-
2
reacting
8-AQ
in
PD(IH)
complexes
including
deprotonated
OH- or Cl- ions and a
solvent molecule.
ligands,
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