Heterobimetallic complexes of palladium(II) and platinum(II) bridged by the ligand 5-phenyl-1,3,4-oxadiazole-2-thione

Article abstract of DOI:10.1016/j.poly.2004.05.006

The complexes [ML₂A₂] or [ML₂B] where M=Pd or Pt, L=5-phenyl-1,3,4-oxadiazole-2-thione ion, A=tertiary monophosphines and B=tertiary diphosphines have been used effectively to prepare bimetallic complexes of the type [A₂M(μ-L)₂M ^′Cl₂] or [BM(μ-L)₂M ^′Cl₂], where M^′=Co, Pd or SnCl ₂. The prepared complexes were characterized by elemental analysis, magnetic susceptibility, IR and UV-Vis spectral data. ³¹P-{ ¹H} NMR data have been applied to characterize the produced linkage isomers.

Full text of DOI:10.1016/j.poly.2004.05.006

Polyhedron 23 (2004) 2013–2020
www.elsevier.com/locate/poly
Heterobimetallic complexes of palladium(II) and
platinum(II) bridged by the ligand 5-phenyl-1,3,4-oxadiazole-2-thione
a
Othman H. Amin , Lamaan J. Al-Hayaly , Subhi A. Al-Jibori , Talal A.K. Al-Allaf
b
c
d,
*
a
Department of Chemistry, College of Science, University of Salahaddin, Erbil, Iraq
b
Department of Chemistry, College of Education, University of Tikrit, Tikrit, Iraq
Department of Chemistry, College of Science for Women, University of Tikrit, Tikrit, Iraq
c
d
Department of Chemistry, College of Basic Sciences, Applied Science University, Shafa Badran, Amman 11931, Jordan
Received 12 May 2004; accepted 18 May 2004
Available online
Abstract
The complexes [ML2A2] or [ML2B] where M ¼ Pd or Pt, L ¼ 5-phenyl-1,3,4-oxadiazole-2-thione ion, A ¼ tertiary monophos-
phines and B ¼ tertiary diphosphines have been used effectively to prepare bimetallic complexes of the type [A2M(l-L)2M0Cl2] or
[BM(l-L)2M0Cl2], where M0 ¼ Co, Pd or SnCl2. The prepared complexes were characterized by elemental analysis, magnetic sus-
ceptibility, IR and UV–Vis spectral data. 31P–{1H} NMR data have been applied to characterize the produced linkage isomers.
Ó 2004 Elsevier Ltd. All rights reserved.
Keywords: Palladium; Platinum; Heterobimetallic; Phosphine; Oxadiazole ligand complexes
1. Introduction
above ligand (L) to give complexes in which L behaves
as a monodentate ligand coordinated to the metal centre
through either S, N or mixture of both (Fig. 1).
The metal complexes of some heterocyclic thiones
attract much attention. The interactions of heavy metals
such as platinum and gold with N,S-donor atoms have
been recognized for their anticancer properties with the
potential to develop metal based drugs [1–6]. Recently,
some research works involving platinum(II) and palla-
dium(II) ions with 8-thiotheophylline and dppm to give
homo- and heterobimetallic complexes have been pub-
lished [7,8]. Other related works on platinum(II) or (IV)
complexes with tertiary phosphines and ligands con-
taining sulfur have been also published recently [9,10].
However, metal complexes containing bis-tertiary
phosphines and heterocyclic-2-thiones are rare [11].
In our recent work [12,13], we reported the prepara-
tion of some palladium(II) and platinum(II) complexes
containing mixed ligands; tertiary monophosphines or
diphosphines and 5-phenyl-1,3,4-oxadiazole-2-thione
(LH). We found that the tertiary monophosphines or
diphosphines reacted with the chelated complexes of the
In the present work, we used the uncoordinated end
of the ligand (L) in the complexes [ML2A2] and [ML2B]
to build up some new types of heterobimetallic com-
plexes bridged by L, i.e., [A2M(l- L)2M0Cl2] and [BM(l-
L)2M0Cl2], where M ¼ Pt or Pd; M0 ¼ Co, Pd or SnCl2;
A ¼ PMePh2; B ¼ Ph2P(CH2)nPPh2 {n ¼ 1, dppm;
n ¼ 2, dppe; n ¼ 3, dppp; n ¼ 4, dppb} and L ¼ 5-
phenyl-1,3,4-oxadiazole-2-thione (–H) (Fig. 1). To the
best of our knowledge, this work is novel.
2. Experimental
2.1. General
31P–{1H} NMR spectra were performed in the labo-
ratories of Prof. Dr. Wilhelm Keim, Insitute for Techi-
sche Chemie der RWTH Achen, Worringer Weg 1,
D-52074 Achen, Germany. IR spectra were recorded on
a PYE-Unicam SP3-300s spectrophotometer in the 200–
4000 cmꢀ1 range using CsI discs. Electronic spectra were
* Corresponding author. Tel.: +962-6-5609999; fax: +962-6-5232899.
E-mail address: talal_al_allaf@hotmail.com (T.A.K. Al-Allaf).
0277-5387/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2004.05.006

2014
O.H. Amin et al. / Polyhedron 23 (2004) 2013–2020
Ph
Ph
4
N
N
5
N
O
H
N
O
1
3
2
S
H
S
(I)
(II)
Ph
O
N
N
N
Ph
S
S
Cl
Cl
P
P
N
M
M'
S
N
N
S
O
M
N
O
O
N
Ph
Ph
(III)
(IV)
Fig. 1. The ligand 5-phenyl-1,3,4-oxidiazole-2-thione (LH), its tautomeric forms (I) and (II) and the suggested structure of its bis(chelated) complexes
(III) and the bridging bimetallic complexes (IV), M ¼ Pd or Pt, M0 ¼ Co, Pd or SnCl2, Pꢁ ꢁ ꢁP ¼ 2PMePh2, dppm, dppe, dppp or dppb.
obtained using a Perkin–Elmer lambda 9 spectropho-
tometer. Elemental analyses were carried out on a CHN
Analyzer, type 1106 (Carlo Erba). Magnetic measure-
ments were recorded on a Bruker BH6 instrument at
room temperature following the Faraday method.
Conductivity measurements were made on a conduc-
tivity meter type CDM 83 70. Melting points were
measured on an Electrothermal 9300 melting point
apparatus.
2.5. [(PMePh2)2Pd(l- L)2CoCl2] ꢁ 2H2O (11)
Solid CoCl2 (0.05 g, 0.38 mmol) was added to a so-
lution of [PdL2(PMePh2)2] (0.15 g, 0.17 mmol) in chlo-
roform (15 ml). The yellow solution turned green. The
mixture was stirred at room temperature for ca. 10 h.
The unreacted CoCl2 was removed by filtration and the
green filtrate was evaporated to dryness. Diethylether
was added and the green solid was filtered off and dried
under vacuum (yield, 0.13 g, 75%).
2.2. Starting materials
The following complexes were prepared and isolated
by a similar method: 13, 17, 20, 23, 25, 28 and 31.
The compounds K2PtCl4, Na2PdCl4 ꢁ 3H2O, PdCl2,
CoCl2, SnCl4 ꢁ 5H2O, PMePh2, dppm, dppe, dppp and
dppb were commercial products and used as supplied.
The ligand 5-phenyl-1,3,4-oxadiazole-2-thione (LH) its
potassium salt (LK) [14], trans-[PdCl2 (DMSO)2], cis-
[PtCl2(DMSO)2] [15], [PdL2] ꢁ H2O, [PtL2], [PdL2
(dppm)] ꢁ H2O, [PtL2(dppm)], [PdL2(dppe)], [PtL2(dppe)]
[12], [PdL2(PMePh2)2] and [PtL2(PMePh2)2] [13] were
prepared according to the literature.
2.6. [(PMePh2)2Pd(l-L)2PdCl2] (12)
Solid trans-[PdCl2(DMSO)2] (0.13 g, 0.38 mmol) was
added with stirring to a solution of [PdL2(PMePh2)2]
(0.2 g, 0.23 mmol) in chloroform (15 ml). The mixture
was stirred at room temperature for ca. 8 h, then filtered.
The filtrate was evaporated to dryness and diethylether
was added. The orange–brown solid thus formed was
filtered off and dried in vacuum (yield, 0.23 g, 95%).
The following complexes were prepared and isolated
by a similar method: 15, 18, 21, 24, 26, 29 and 32.
2.3. [PdL2(dppp)] (4) and [PdL2(dppb)] (5)
These complexes were prepared by a method similar
to that reported for the preparation of [PdL2-
(dppm)] ꢁ H2O [12].
2.7. [(PMePh2)2Pd(l-L)2SnCl4] (13)
Solid SnCl4 ꢁ 5H2O (0.07 g, 0.22 mmol) was added
2.4. [PtL2(dppp)] (9) and [PtL2(dppb)] (10)
with stirring to
a
clear yellow solution of
[PdL2(PMePh2)2] (0.14 g, 0.16 mmol) in chloroform (12
ml). The mixture was stirred at room temperature for ca.
10 h, then filtered. The filtrate was evaporated to dryness
These complexes were prepared by a method similar
to that reported for the preparation of [PtL2(dppm)] [12].

O.H. Amin et al. / Polyhedron 23 (2004) 2013–2020
2015
and diethylether was added. The resulting yellow solid
was filtered off and dried in vacuum (yield, 0.13 g, 71%).
The following complexes were prepared and isolated
by a similar method: 16, 19, 22, 27, 30 and 33.
IR spectra of the Pd–Co or Pt–Co complexes showed
two medium to strong bands at around 310–330 cmꢀ1
,
assigned to m(Co–Cl) in an octahedral environment
(complexes 11, 17, 20, 25, 28 and 31), or a single strong
band at around 310 or 315 cmꢀ1 for square planar and
tetrahedral cobalt complexes (complexes 14 and 23) [18].
The far IR spectra of the Pd–Sn complexes showed a
strong single band at around 310–330 cmꢀ1 assigned to
(Sn–Cl) [19], while the IR spectra of the Pd–Pd com-
plexes (12, 15, 18, 21 and 24) showed in each case two
3. Results and discussion
3.1. Synthesis of the complexes
We reported previously that the reaction of cis-
[PtCl2(B)] {B ¼ Ph2P(CH2)PPh2 (dppm) and Ph2P
(CH2)2PPh2 (dppe)} with the potassium salt of the li-
gand 5-phenyl-1,3,4-oxadiazole-2-thione (LK) or the
reaction of trans-[PtL2] with dppm or dppe gave com-
plexes of the type [PtL2(B)] which was a single linkage
isomer when B ¼ dppm [12]. From the J(Pt–P) value
(2714 Hz), we believed that this was the S-bonded iso-
mer. When B ¼ dppe, two linkage isomers in the ratio
1:1 were obtained, the S-bonded isomer with a low J(Pt–
P) value (2346 Hz) and the N-bonded isomer with high
J(Pt–P) value (3088 Hz). Now, we have extended this
series to include the ligands Ph2P(CH2)3PPh2 (dppp)
and Ph2P(CH2)4PPh2 (dppb). From the 31P–{1H} NMR
data, we found that for the complex [PtL2(dppp)], a
single isomer is obtained and from its J(Pt–P) value
(3023 Hz), we believed that it is the N-bonded isomer.
Treatment of a solution of [ML2(PMePh2)2] or
[ML2(B)] (B ¼ dppm, dppe, dppp or dppb) with solid
CoCl2, trans-[PdCl2(DMSO)2] or SnCl4 ꢁ 5H2O in chlo-
roform yielded heterobimetallic complexes of the type
[(PMePh2)2M(l-L)2M0Cl2] or [(B)M(l-L)2M0Cl2].
medium intensity bands at 350, 290 or 310, 290 cmꢀ1
,
respectively, which are assigned to (Pd–Cl) in a cis-ar-
rangement [20]. Other IR data are given in Table 2.
The magnetic susceptibility measurements for the
prepared complexes indicated that all of them are dia-
magnetic except for some of the cobalt complexes (11,
17, 20, 23, 25, 28 and 31). The magnetic susceptibility
value of complex 23 is 4.5 BM, which on the basis of this
value and the spectral data was assigned to have a tet-
rahedral geometry [21]. The values 4.9–5.2 BM for the
remaining cobalt complexes suggest an octahedral ar-
rangement around cobalt(II), which compare very well
with reported values for octahedral complexes of co-
balt(II) (4.7–5.2 BM) [22–24].
3.2.2. 31P–{1H} NMR spectra
The 31P–{1H} NMR data of some of the prepared
complexes are given in Table 4.
The spectrum of [PtL2(dppm)] showed a singlet at
dP ꢀ 49:2 ppm with associated platinum satellites, J(Pt–
P) ¼ 2714 Hz. The negative value of the dP indicates that
dppm behaves as a chelating ligand [25]. The low J(Pt–
P) value suggests that the trans-atom is a sulfur rather
than a nitrogen atom [8]. The sulfur atom has the ability
to compete with the phosphorus atom on back donation
from the platinum. Therefore, it lowers the J(Pt–P) va-
lue. The small volume occupied by dppm permits the
ligand (L) to bond through the preferable sulfur atom.
This makes the ligands occupy a bigger volume [26]. The
31P–{1H} NMR spectrum of [(dppm)Pt(l-L)2PdCl2]
showed a singlet at dP ) 63.0 ppm associated with plat-
inum satellites, J(Pt–P) ¼ 3106 Hz; i.e., 392 Hz higher
than that of the starting complex [PtL2(dppm)], indi-
cating a single isomer and that the bridging ligand (L) is
bonded to platinum via the sulfur end, while it is bonded
to palladium via the nitrogen end.
We reported in our recent work that the 31P–{1H}
NMR spectrum of [PtL2(dppe)] showed two singlets at
dP 48.1 and 48.8 ppm in the ratio of 1:1, each associated
with platinum satellites, J(Pt–P) ¼ 3088 and 2346 Hz,
respectively, assigned to the linkage N-bonded and the
S-bonded isomers, respectively [12]. Reaction of the
isomeric mixture with trans-[PdCl2(DMSO)2] gave a
single heterobimetallic isomer at dP 42.4 ppm with
J(Pt–P) ¼ 3727 Hz, i.e., 639 Hz higher than that of
the starting complex [PtL2(dppe)]. The J(Pt–P) value
3.2. Characterization of complexes
The complexes were identified by elemental analysis,
31P–{1H} NMR, IR, UV–Vis spectra, magnetic sus-
ceptibility and conductivity measurements and their
data are listed in Tables 1–4.
The synthesised heterobimetallic complexes are stable
in the solid state as well as in solution except for the
cobalt complexes which showed some instability in
aqueous or alcoholic solvents. For this reason, these
solvents were avoided in the preparation and charac-
terization of the cobalt complexes Although the molar
conductivities of the complexes in acetonitrile are
greater than those in chloroform (Table 3), due to the
higher dielectric constant of acetonitrile, nevertheless the
values in both solvents are too low to suggest that they
are non-electrolytes [16].
3.2.1. IR spectra and magnetic moments
The IR spectra of the prepared complexes (Table 2)
showed weak to strong bands at ca. 1550, 1435, 960 and
775 cmꢀ1, which may be assigned to the thioamide vi-
brational bands I, II, III and IV, respectively [17]. The

2016
O.H. Amin et al. / Polyhedron 23 (2004) 2013–2020
Table 1
Physical properties of complexes 1–33
Sequence Complex
Colour
Yield
Melting point
(°C)a
Found (calc) (%)
C
H
N
1
2
[PdL2(PMePh2)2]
[PdL2(dppm)]
yellow
orange
95
76
93
94
94
56
77
83
76
82
75
229–231
140–142
233–234
136–138
232–235
261–263
146–148
264–268
176–178
168–169
251–252
58.7 (58.9)
58.3 (57.8)
58.7 (59.1)
59.1 (60.0)
59.6 (59.8)
53.1 (52.7)
52.8 (53.1)
53.2 (53.0)
53.7 (53.9)
54.2 (54.4)
49.1 (48.7)
4.2 (4.2)
3.8 (3.7)
3.9 (3.9)
4.1 (3.7)
4.3 (4.2)
3.8 (3.8)
3.4 (3.3)
3.6 (3.4)
3.7 (3.7)
3.9 (3.8)
3.5 (3.4)
6.5 (6.7)
6.6 (6.7)
6.5 (6.8)
6.4 (6.2)
6.3 (6.3)
5.9 (6.1)
6.0 (5.8)
5.9 (6.0)
5.8 (5.9)
5.7 (5.9)
5.5 (5.4)
3
[PdL2(dppe)]
[PdL2(dppp)]
yellow
yellow
4
5
[PdL2(dppb)]
[PtL2(PMePh2)2]
yellow–orange
pale yellow
off white
off white
off white
pale yellow
green
6
7
[PtL2(dppm)]
[PtL2(dppe)]
8
9
[PtL2(dppp)]
[PtL2(dppb)]
10
11
[(PMePh2)2Pd(l-
L)2CoCl2] ꢁ 2H2O
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
[(PMePh2)2Pd(l-L)2PdCl2]
[(PMePh2)2Pd(l-L)2SnCl4]
[(dppm)Pd(l-L)2CoCl2]
[(dppm)Pd(l-L)2PdCl2]
[(dppm)Pd(l-L)2SnCl4]
[(dppe)Pd(lL)2CoCl2] ꢁ 2HO
[(dppe)Pd(l-L)2PdCl2]
[(dppe)Pd(l-L)2SnCl4]
[(dppp)Pd(l-L)2CoCl2] ꢁ H2O
[(dppp)Pd(l-L)2PdCl2]
[(dppp)Pd(l-L)2SnCl4]
[(PMePh2)2Pt(l-L)2CoCl2]
[(PMePh2)2Pt(l-L)2PdCl2]
[(dppm)Pt(l-L)2CoCl2] ꢁ 2H2O
[(dppm)Pt(l-L)2PdCl2]
[(dppm)Pd(l-L)2SnCl4]
[(dppe)Pt(l-L)2CoCl2] ꢁ 2H2O
[(dppe)Pt(l-L)2PdCl2]
[(dppe)Pt(l-L)2SnCl4]
[(dppp)Pt(l-L)2CoCl2] ꢁ 2H2O
[(dppp)Pt(l-L)2PdCl2]
[(dppp)Pt(l-L)2SnCl4]
orange–brown
yellow
green
95
71
73
97
89
75
60
61
79
72
83
87
95
95
97
48
91
94
94
88
89
90
203–210
148–150
186–187
279–281
189–191
265–258
314–316
154–156
196–198
208–210
152–154
187–189
245–247
118–120
326–328
198–199
218–220
294–296
178–180
228–230
318–320
197–199
48.8 49.2
3.5 (3.3)
3.2 (3.4)
3.3 (3.4)
3.1 (3.0)
2.9 (3.0)
3.3 (3.3)
3.5 (3.4)
3.0 (3.0)
3.5 (3.4)
3.4 (3.3)
3.2 (3.2)
3.3 (3.3)
3.2 (3.4)
2.9 (2.9)
2.9 (2.9)
2.7 (2.7)
3.3 (3.2)
3.0 (3.1)
2.8 (2.8)
3.2 (3.2)
3.2 (3.1)
2.9 (3.1)
5.4 (5.6)
5.0 (4.9)
5.7 (5.6)
5.5 (5.6)
5.1 (4.9)
5.5 (5.5)
5.4 (5.5)
5.0 (5.1)
5.4 (5.3)
5.3 (5.4)
4.9 (4.9)
5.2 (5.1)
5.0 (5.3)
5.1 (5.2)
5.0 (5.2)
5.7 (5.6)
5.0 (5.0)
5.0 (5.1)
4.6 (4.5)
5.0 (4.9)
4.9 (5.1)
4.6 (4.5)
44.9 (44.6)
50.5 (50.4)
49.2 (49.1)
44.5 (44.3)
49.6 (49.7)
47.8 (47.9)
45.0 (44.8)
48.7 (48.9)
49.1 (49.3)
45.5 (45.8)
46.7 (46.4)
44.8 (45.1)
44.7 (44.7)
46.3 (46.0)
41.2 (41.5)
46.1 (46.0)
44.9 (44.8)
42.0 (42.1)
46.8 (47.0)
44.9 (44.8)
42.5 (42.7)
orange
yellow
green
orange
yellow
green
orange–brown
yellow
blue–green
pale orange
blue–green
orange
pale yellow
green
orange–brown
pale brown
blue–green
orange–brown
off white
a Complexes melt with decomposition.
indicated that it is the N-bonded isomer cis–cis-
[(dppe)Pt{l-L(NS)}2PdCl2]. However, the difference in
J(Pt–P) values, i.e., 392 Hz in the case of the dppm
complex and 639 Hz in the case of dppe may be ex-
plained on the basis of the strain presented by the dppm
chelate ring which is not present in the dppe and dppp
chelate rings.
The 31P–{1H} NMR spectrum of [PtL2(dppp)]
showed a singlet at dP ) 1.92 ppm with J(Pt–P) ¼ 3023
Hz, indicating the presence of a single isomer. The J(Pt–
P) value indicates that it is the N-bonded isomer. Re-
action of this complex with trans-[PtCl2(DMSO)2] gave
the heterobimetallic complex cis–cis-[(dppp)Pt{l-
L(NS)}2PdCl2] as indicated from the dP which is )4.37
ppm and J(Pt–P) which is 3375 Hz.
age isomer produced. This trend is in consistent with
that reported for the complexes [Pd(SCN)2{Ph2P
(CH2)nPPh2}] n ¼ 1, 2 or 3 [26].
On the other hand, the 31P–{1H} NMR spectrum of
trans-[PdL2(PMePh2)2] showed two singlets at dP 13.5
and 12.4 ppm in the ratio of 80% and 20%, respectively.
No coupling between the two signals was observed
which indicates the presence of two compounds. We
believe that these are, probably, due to the two linkage
isomers, the S-bonded and the N-bonded 5-phenyl-
1,3,4-oxadiazole-2-thione. The possibility of having an
S,N-bonded isomer is ruled out since the complex we
obtained has a trans-configuration and not the cis-one.
The cis-isomer should give an AX spin system (doublet
of doublets) in the 31P NMR spectrum and in our case
we found only two singlets in the spectrum. Several at-
tempts carried out to grow a crystal of the complex for
X-ray analysis were unsuccessful. On treatment of this
isomeric mixture with trans-[PdCl2(DMSO)2], a mixture
of linkage heterobimetallic isomers of the type trans-
[(PMePh2)2Pd(l-L)2PdCl2] were observed, as shown
The above trend of changing the point of attachment
of the ligand 5-phenyl-1,3,4-oxadiazole-2-thione from
an S-bonded, in the presence of the dppm ligand, to a
1:1 mixture of the S- and N-bonded with dppe, to an N-
bonded in the presence of dppp reflects the steric effect
exerted by the diphosphine ligands on the type of link-

Table 2
IR spectral dataa of complexes 1–33
Complex
Thioamide bands
Others
I
II
III
IV
m(OH)
m(CH)
m(M–N)
m(M–S)
m(M–Cl)
m(P–Me)
m(COC)
m(N–N)
1
2
1550w
1545w
1545m
1545w
1570w
1550w
1555w
1543w
1545w
1550w
1555w
1558w
1550w
1555w
1555w
1568w
1557w
1565w
1565w
1555s
1435s
1430s
1435s
1430s
1430s
1430s
1430s
1425s
1430s
1430s
1425s
1430s
1430s
1430s
1435s
1432s
1435s
1430s
1430s
1430s
1430s
1435s
1425s
1430s
1430s
1430s
1440s
1430s
1435s
1435s
1425s
1430s
1432s
995m
960m
960w
960w
970
777m, 760s
772s, 745s
780m, 752m
775m, 745s
470s
3055w, 2920w
3045m, 2890w
3045m, 2960m
3050m, 2920w
3050m, 2920w
3050m, 2920w
3055m, 2960w
3040m, 2940w
3040m, 2905w
3045w, 2910w
3050w, 2910w
3050w, 2910w
3050w, 2910w
3040w, 2900w
3040w, 2900w
3040m, 2950w
3050w, 2915w
3050w, 2980w
3050, 2950w
510s, 459m
500s, 480m
530a, 483m
515s, 490m
520s, 500s
510s, 490m
510s, 486m
530s, 480m
520s
445m
450w
437m
435w
890s
1160m
1154s
1150s
1480m
1475m
1480m
1480s
3415w
3
4
3400s
3400s
1163s
1175s
5
1477m
1478m
1480s
6
960w
960m
960m
970w
965w
960m
960m
960m
955w
950w
970s
775m
420m
428w
438w
440w
430w
895s
1155s
1160s
7
772s, 740s
772m, 738s
775m, 745s
775m, 745s
775m, 745s
775m, 740s
772m, 740s
775s, 740s
773m, 740s
772s, 740s
775m, 753m
760s, 720s
775m, 750m
773m, 750s
775m, 750s
772m, 750s
775m, 740s
775m, 740s
775m, 742s
775m, 742s
775m, 735s
778m, 732s
775m, 755s
775m, 755s
775m, 745s
775m, 750s
770w, 750s
3420s
3380s
8
1170m
1152s
1480s
9
1475m
1480m
1480m
1480m
1477m
1475m
1480w
1478sw
1480m
1477m
1480s
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
515s, 485m
510s, 490m
512s, 490m
510s, 485m
500s, 475m
520s, 480m
505m
1165m
1160m
1165m
1170m
1177s
3400m
3450w
3240w
3400s
340s, 315m
350s, 314m
325s
890s
900s
890s
450m
450m
430w
435
315s
350m, 290s
303m
3450m
1165m
1180m
1170s
425m
440w
440w
445w
430w
430
960w
1000m
970m
950m
950m
945m
995m
965m
955m
955m
965m
960m
955w
955w
975w
950m
970w
3400s
530s, 485m
530s, 485m
350s, 490m
500s
340m, 315s
315s, 290m
330s
1163m
1163s
1160s
3400s
3440s
3450s
3046m, 2980w
3042m, 2980w
3140w, 2950w
3040s, 2960w
3060m, 2920w
3050m, 2940w
3040m, 2910w
3040w, 2900w
3050w, 2950w
3050, 2910w
330s, 316s
312s, 290s
330s
1480s
1477m
1478s
1555s
510s
510s
1155m
1172s
1170s
1548w
1524m
1556m
1552m
1555m
1555m
1550w
1555m
1560w
1552m
1557m
1552m
430w
430w
420w
450w
430w
460w
430w
438w
438w
430w
440w
435w
510s, 490s
510s, 490s
510s, 485m
520s, 485m
490s
310s
895s
900s
1475m
1480m
1477m
1480m
1480m
1480m
1480m
1480m
1475m
1480m
1480s
350s, 320m
330m, 310m
310m, 295m
315m
1160s
1170s
3400s
3400b
1175m
1175m
1170m
1160m
1175m
1155m
1158m
1165m
535s, 485m
530s, 490m
530s, 490m
510s
340m, 320m
318s, 293s
330s
3480b
3060w, 2940w
3040w, 2920w
3050w, 2912w
305w, 2920w
335m, 320m
310s, 290m
325s
518s
518s
aFor IR data (cmꢀ1); b: broad, m: medium, s: strong, w: weak bands.

2018
O.H. Amin et al. / Polyhedron 23 (2004) 2013–2020
Table 3
Electronic spectra, magnetic moments and molar conductivity of complexes 1–33
KM (Xꢀ1 cm2 molꢀ1
)
Complex
kmax (nm)
Assignments
leff (BM)a
CHCl3
0.2
CH3CN
3.2
1
1
2
3
375
336
266
440
337
300
416
350
272
330
265
414
355
265
375
324
660
370
262
262
250
262
342
260
633
390
340
300
420
330
260
440
332
265
420
334
263
345
260
480
350
264
631
442
325
262
450
332
264
355
262
620
454
264
461
339
265
420
335
266
1A1g ! B1g
0.2 Pd sq.pl.
0.2 Pd sq.pl.
0.2 Pd sq.pl.
1
1E1g ! A1g
c.t.
1
1A1g ! B1g
0.16
0.18
3.2
3.0
1
1E1g ! A1g
c.t.
1
1A1g ! A2g
1Eg ! B1g
1
c.t.
1
4
5
1Eg ! B1g
0.2 Pd sq.pl.
0.1 Pd sq.pl.
0.2
0.2
3.4
3.0
c.t
1A1g ! A2g
1
E1g ! Bg
c.t.
1
6
7
1A1g ! B1g
0.1 Pt sq.pl.
0.2 Pt sq.pl.
0.16
0.2
2.6
2.1
c.t
B2g ! B1g
1
A1g ! B1g
c.t
8
c.t.
c.t.
c.t.
0.2 Pt sq.pl.
0.2
3.7
9
10
0.2 Pt sq.pl.
0.1 Pt sq.pl.
0.18
0.19
5.0
4.5
1
A1g ! B1g
c.t.
4
11
4A2F ! T1F
4.9 Pd sq.pl., Co o.h. 0.24
14.6
1
1A1g ! B1g
1
E1g ! A1g
c.t.
1
12
13
14
1A1g ! B1g
0.1 Pd sq.pl.
0.2 Pd sq.pl.
0.24
0.25
0.20
5.8
5.7
3.7
1E1g ! A1g
c.t
1
1A1g ! B1g
1
1E1g ! A1g
c.t.
2
2A1g ! Eg
0.1 Pd
sq. pl., Co sq.pl.
c.t.
c.t.
1
15
16
1E1g ! B1g
0.1 Pd sq.pl.
0.1 Pd sq.pl.
c.t.
1
1A1g ! A2g
0.22
11.2
15.9
1
1E1g ! B1g
c.t.
4
17
18
4T1gF ! A2g(F)
5.1 Pd sq.pl., Co o.h. 0.20
4T1gF ! T1g(P)
4
c.t.
c.t.
1
1A1g ! B1g
0.2 Pd sq.pl.
0.2 Pd sq.pl.
0.21
0.23
2.5
1Eg ! B1g
1
c.t.
E1g ! B1g
1
19
20
20.7
14.0
c.t.
4T1gF ! A2g(F)
4.9 Pd sq.pl., Co o.h. 0.21
4
4T1gF ! T1g(P)
4
c.t.
A1g ! A2g
21
22
0.1 Pd sq.pl.
0.1 Pd sq.pl.
0.21
0.23
23.0
18.3
1
E1g ! B1g
c.t.
A1g ! A2g
1
E1g ! B1g
c.t

O.H. Amin et al. / Polyhedron 23 (2004) 2013–2020
2019
Table 3 (continued)
KM (Xꢀ1 cm2 molꢀ1
)
Complex
kmax (nm)
Assignments
leff (BM)a
CHCl3
0.20
CH3CN
3.6
4
23
622
370
348
264
318
266
621
389
330
259
262
335
263
621
416
272
450
332
264
335
263
634
480
303
490
370
272
336
264
4A2F ! T1g(P)
4.5 Pt sq.pl., Co t.h.
A1g ! B1g
E1g ! B1g
c.t
1
24
25
E1g ! B1g
0.1 Pt sq.pl.
0.20
20.9
8.5
c.t.
4T1gF ! A2g(F)
5.2 Pt sq.pl., Co o.h. 0.20
4
3
1A1g ! B1(g)
E1g ! B1g
c.t.
c.t.
26
27
0.1 Pt sq.pl.
0.2 Pt sq.pl.
0.20
0.23
2.7
8.0
3
1A1g ! B1g
c.t.
4
28
29
4A2gF ! T1g(F)
0.1 Pt sq.pl., Co o.h. 0.20
2.1
3.1
4T1gF ! T1g(P)
4
c.t.
A1g ! B1g
E1g ! B1g
c.t.
0.1 Pt sq.pl.
0.2 Pt sq.pl.
0.20
0.20
3
30
31
1A1g ! B1g
7.6
c.t.
4A2gF ! T1g(F)
5.0 Pt sq.pl., Co o.h. 0.20
0.1 Pt sq.pl., Pd sq.pl. 0.20
13.8
4
4T1gF ! T1g(P)
4
c.t.
1
32
33
1A1g ! A2g
12.0
14.0
A1g ! B1g
c.t
A1g ! B1g
1
0.1 Pt sq.pl.
0.20
c.t.
a Abbreviations, sq.pl., o.h. and t.h. are for square planar, octahedral and tetrahedral environment, respectively.
Table 4
31P–{1H} NMR data (d ppm and J Hz)a of some of the prepared complexes
Complex
Sequence
dp
J(Pt–P)
Comments
cis-[PdCl2(PMePh2)2]c
trans-[PdCl2(PMePh2)2]c
trans-[PdL2(PMePh2)2]
)19.1
)7.8
13.5
12.4
23.0
23.6
)39.2
)53.2
63.0
65.2
72.0
)1.2
41.3
9.6
1
80% S-bonded
20% N-bonded
65% S-bonded
35% N-bonded
trans-[(PMePh2)2Pd(l-L)2PdCl2]
12
[PdL2(dppm)]
[(dppm)Pd(l-L)2PdCl2]
[PdL2(dppe)]
2
15
3
[(dppe)Pd(l-L)2PdCl2]
[(dppe)Pd(l-L)2SnCl4]
cis-[PtCl2(PMePh2)2]c
trans-[PtCl2(PMePh2)2]
cis-[PtL2(PMePh2)2]
[PtCl2(dppm)]c
18
19
3616
2028
2567
3078
2714
3106
3618
3088b
2346b
3727
3420
3023
3375
6
)64.3
)49.2
)63.0
45.3
48.1
48.8
42.4
)5.6
)1.9
)4.4
[PtL2(dppm)]
7
26
[(dppm)Pt(l-L)2PdCl2]
[PtCl2(dppe)]c
[PtL2(dppe)]
8
50% N-bonded
50% S-bonded
[(dppe)Pt(l-L)2PdCl2]
[PtCl2(dppp)]c
[PtL2(dppp)]
29
9
32
[(dppp)Pt(l-L)2PdCl2]
a Measured in CDCl3 downfield from 85% H3PO4.
b Published previously [12] in a reverse order.
c These are listed here for comparison.

2020
O.H. Amin et al. / Polyhedron 23 (2004) 2013–2020
from the 31P–{1H} NMR spectrum. The spectrum of
this heterobimetallic mixture showed two singlets at dP
23.0 and 23.6 ppm in the ratio of 65% and 35%, re-
spectively. We believe that these correspond to the S-
bonded and N-bonded heterobimetallic isomers, i.e.,
cis–cis-[(PMePh2)2Pd{l-L(SN)}2PdCl2] and cis–cis-
[(PMePh2)2Pd{l-L(NS)}2PdCl2], respectively.
[5] J. Reedijk, Inorg. Chim. Acta 198–200 (1992) 873.
[6] L.T. McCaffrey, W. Henderson, B.K. Nicholson, J.E.
Mackay, M.B. Dinger, J. Chem. Soc., Dalton Trans. (1997)
2577.
[7] L.T. McCaffrey, W. Henderson, B.K. Nicholson, Polyhedron 17
(1998) 221.
[8] E. Colacio, R. Cuesta, M. Ghazi, M. Angeles Huertas, J.M.
Moreno, A. Navarrete, Inorg. Chem. 36 (1997) 1652.
[9] J.M. Teuben, S.S.G.E. van Boom, J. Reedijk, J. Chem. Soc.,
Dalton Trans. (1997) 3979.
The 31P–{1H} NMR spectrum of [PdL2(dppm)]
showed a singlet at dP ) 39.2 ppm while that of the bi-
metallic complex [(dppm)Pd(l-L)2PdCl2] showed it to
be at dP ) 53.3 ppm. The negative sign of the chemical
shifts indicate again that dppm behaves as a chelating
ligand in both the mononuclear and the binuclear
complexes [25]. Other 31P–{1H} NMR data of the other
palladium complexes are given in Table 4.
[10] E.G. Talman, W. Bruning, J. Reedijk, A.L. Spek, N. Veldman,
Inorg. Chem. 36 (1997) 854.
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[13] A.M. Qadir, A.I. Abdulla, S.A. Al-Jibori, T.A.K. Al-Allaf, Asian
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Acknowledgements
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[17] A.H. Jassim, Ph.D. Thesis, Saddam University of Engineering and
Science, Baghdad, Iraq, 1993.
We thank Prof. Dr. Wilhelm Keim, Institute for
Technische Chemie der RWTH Aachen, Worringer
Weg1, D-52074 Aachen, Germany, for his help in ob-
taining the 31P–{1H} NMR data.
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