Mono- and bimetallic platinum(II) and palladium(II) complexes containing fluorinated benzothiolates

Article abstract of DOI:10.1016/j.poly.2007.05.025

The new mononuclear palladium(II) and platinum(II) [M(p-SC₆F₄(CF₃))₂(dppe)] complexes M = Pd 1a, Pt 2a; [M(o-SC₆H₄(CF₃))₂(dppe)] M = Pd 1d, Pt 2d as well as the previously known [M(SC₆F₅)₂(dppe)] M = Pd 1b, Pt 2b and [M(p-SC₆HF₄)₂(dppe)] M = Pd 1c, Pt 2c, have been used as metalloligands for the preparation of the heteroleptic bimetallic complexes [M₂(μ-SRf)₂(dppe)₂](SO₃CF ₃)₂ M = Pd, Rf = p-C₆F₄(CF₃) 3a, C₆F₅ 3b, p-C₆HF₄ 3c, o-C₆H₄(CF₃) 3d; M = Pt, Rf = p-C₆F₄(CF₃) 4a, C₆F₅ 4b, p-C₆HF₄ 4c and o-C₆H₄(CF₃) 4d. Variable temperature ¹⁹F NMR experiments show that the fluorothiolate bridged bimetallic compounds are fluxional in solution whereas mononuclear complexes are not. The solid state X-ray diffraction structures of [Pd(p-SC₆HF₄)₂(dppe)] (1c), [Pt(SC₆F₅)₂(dppe)] (2b) and [Pt(o-SC₆H₄(CF₃))₂(dppe)] (2d) show square-planar coordination around the metal centers. The solid state molecular structure of the compound [Pt₂(μ-o-SC₆H₄(CF₃)) ₂(dppe)₂](SO₃CF₃)₂ (4d), exhibit a planar [Pt₂(μ-S)₂] ring with the sulfur substituents in an anti configuration.

Full text of DOI:10.1016/j.poly.2007.05.025

Polyhedron 26 (2007) 4276–4286
www.elsevier.com/locate/poly
Mono- and bimetallic platinum(II) and palladium(II)
complexes containing fluorinated benzothiolates
a
b
c,
*
`
Guillermina Rivera , Sylvain Bernes , Hugo Torrens
a
Facultad de Estudios Superiores Cuautitla´n, UNAM, Campo 1, 54740 Cuautitla´n Izcalli, Estado de Me´xico, Mexico
b
DEP, Facultad Ciencias Quı´micas, UANL, Guerrero y Progreso S/N, 64570 Monterrey, Nuevo Leo´n, Mexico
c
Facultad de Quı´mica, UNAM, Ciudad Universitaria, 04510 Me´xico D.F., Mexico
Received 29 March 2007; accepted 15 May 2007
Available online 26 May 2007
Abstract
The new mononuclear palladium(II) and platinum(II) [M(p-SC6F4(CF3))2(dppe)] complexes M = Pd 1a, Pt 2a; [M(o-SC6H4-
(CF3))2(dppe)] M = Pd 1d, Pt 2d as well as the previously known [M(SC6F5)2(dppe)] M = Pd 1b, Pt 2b and [M(p-SC6HF4)2(dppe)]
M = Pd 1c, Pt 2c, have been used as metalloligands for the preparation of the heteroleptic bimetallic complexes [M2(l-SRf)2(dppe)2]-
(SO3CF3)2 M = Pd, Rf = p-C6F4(CF3) 3a, C6F5 3b, p-C6HF4 3c, o-C6H4(CF3) 3d; M = Pt, Rf = p-C6F4(CF3) 4a, C6F5 4b, p-C6HF4
4c and o-C6H4(CF3) 4d. Variable temperature 19F NMR experiments show that the fluorothiolate bridged bimetallic compounds are flux-
ional in solution whereas mononuclear complexes are not. The solid state X-ray diffraction structures of [Pd(p-SC6HF4)2(dppe)] (1c),
[Pt(SC6F5)2(dppe)] (2b) and [Pt(o-SC6H4(CF3))2(dppe)] (2d) show square-planar coordination around the metal centers. The solid state
molecular structure of the compound [Pt2(l-o-SC6H4(CF3))2(dppe)2](SO3CF3)2 (4d), exhibit a planar [Pt2(l-S)2] ring with the sulfur sub-
stituents in an anti configuration.
Ó 2007 Elsevier Ltd. All rights reserved.
Keywords: Fluorine; Thiolates; Palladium; Platinum; Variable temperature NMR
1. Introduction
In order to further explore the chemistry and fluxional
behavior of [M2(l-SR)2(L–L)2] compounds, the prepara-
tion and characterization of a variety of palladium and
platinum complexes with chelating diphosphine, as a fixed
auxiliary ligand, and a series of fluorinated thiolates have
been undertaken.
In this paper the following bimetallic complexes are
reported: [M2(l-SRf)2(dppe)2](SO3CF3)2, M = Pd, Rf = p-
C6F4(CF3) 3a; C6F5 3b; p-SC6HF4 3c; o-C6H4(CF3) 3d;
M = Pt, Rf = p-C6F4(CF3) 4a; C6F5 4b; p-C6HF4 4c and o-
C6H4(CF3) 4d. The monometallic compounds [M(SRf)2-
(dppe)], used as metalloligands, are also described. Four of
them have not been previously reported: Rf = p-
C6F4(CF3), M = Pd 1a, Pt 2a and Rf = o-C6H4(CF3),
M = Pd 1d, Pt 2d. We have studied the dynamic behavior
of these complexes using 19F NMR. The crystal and molec-
ular structures of [Pd(p-SC6HF4)2(dppe)] (1c), [Pt-
(SC6F5)2(dppe)] (2b), [Pt(o-SC6H4(CF3))2(dppe)] (2d) and
The coordination chemistry of thiolates with platinum
group metals has developed extensively over the last few
decades [1,2]. In particular, bimetallic complexes with thio-
late ligands have played an important role in areas such as
bioinorganic chemistry, synthesis and catalysis [3–8]. On
the other hand, the relatively newer analogous chemistry
of fluorine-containing homologues is still developing [9].
We have a long standing interest [10] on the dynamic
behavior exhibited, in solution, by compounds with general
formula [M2(l-SR)2(L)4] (R = fluorinated substituent)
which has been found to arise from three main processes:
ring flipping, inversion of configuration at the sulfur atoms
and restricted rotation around the C–S bonds.
*
Corresponding author. Tel./fax: +52 56223724.
E-mail address: torrens@servidor.unam.mx (H. Torrens).
0277-5387/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2007.05.025

G. Rivera et al. / Polyhedron 26 (2007) 4276–4286
4277
[Pt2(l-o-SC6H4(CF3))2(dppe)2](SO3CF3)2 (4d) are also
described.
of these polymeric species, relatively short reaction times
were used.
Variable temperature 19F NMR experiments (25 °C
down to ꢀ90 °C) have been carried out for compounds
2a to 2c which remained as sharp signals showing no
changes on their absorption spectra.
2. Results and discussion
IR spectra of compounds 1–4 show the expected absorp-
tions arising from the common dppe ligands and the corre-
sponding thiolate moiety present in each compound. In
addition, complexes 3 and 4 exhibit the characteristic
The molecular structures of [Pd(p-SC6HF4)2(dppe)] (1c),
[Pt(SC6F5)2(dppe)] (2b) and [Pt(o-SC6H4(CF3))2(dppe)]
(2d) are shown in Figs. 1–3 respectively, selected bond dis-
tances and angles are shown in Table 1.
ꢀ
bands of the SO3CF3 anion.
In terms of NMR, the magnetic systems corresponding
to the fluorinated rings C6F5, p-C6HF4 and p-C6F4(CF3)
can be described as AA0BB0C, AA0BB0X and AA0BB0X3
respectively. All three systems share ortho (A = F) and
meta (B = F) fluorine nuclei, bearing different para substit-
uents, namely, C = F, X = H, and X3 = CF3. For the o-
C6H4(CF3) fragment, the magnetic system can be described
Coordination around metal centers in compounds 1c, 2b
and 2d are distorted square-planar (the angles around pal-
ladium and platinum add to 360.02°, 360.18° and 357.11°
(molecule 1) and 360.36° (molecule 2) respectively).
˚
˚
The Pd–S (2.3642(7) A) and Pd–P (2.2703(7) A) bond
lengths in 1c are slightly longer than those found by Wei
and Liu [14] in [Pd(SC6H5)2(dppe)] for which these bonds
1
as ABCDX3. H, 19F and 31P NMR parameters for com-
are Pd–S 2.3486(7) A and Pd–P 2.2612(7) A whereas in
[Pd(SC6F5)2(dppe)] these distances are Pd–S 2.354(1) and
2.361(1) and Pd–P 2.268(1) and 2.258(1) [15]. The analo-
gous nickel complex [Ni(p-SC6HF4)2(dppe)] has also been
structurally characterized [16] showing shorter Pd–S bond
distance than those found for 1c.
˚
˚
pounds 1 and 4, in agreement with the descriptions above,
are listed in Section 4.
31P NMR spectra of compounds 1 and 3 exhibit a sin-
gle absorption whereas platinum derivatives 2 and 4
show, in addition, the expected 195Pt satellites. Plati-
num–phosphorous coupling constants show differences
of up to ca. 150 Hz from compound 2a to compound
2d and increases with the fluorination degree of the ring,
from 2879 Hz when Rf = o-C6H4(CF3) to 3033 Hz when
Rf = C6F4(CF3), probably reflecting the trans influence
order in this series. On the other hand palladium com-
plexes show 31P chemical shifts 7–13 ppm upfield when
compared with the corresponding d 31P from the plati-
num analogs.
The bonding angles in 1c vary between 85.07° and
100.37° with the widest angle opposite to the P(1)–Pd–
P(1)i (symmetry code i: see Table 1) which, due to the che-
lating bite, is necessarily the smallest one.
For the molecular structure of compound [Pt-
(o-SC6H4(CF3))2(dppe)] (2d) the asymmetric unit allocates
two independent molecules of the platinum complex with
significantly different conformations of the phenyl groups
at the chelate ligand in the molecule. Both platinum com-
plexes 2b and 2d show shorter Pt–S bond distances than
2.1. Monometallic complexes
Metathesis reactions of [MCl2(dppe)] M = Pd or Pt with
the corresponding lead thiolate (Eq. (1)) render the metal-
loligands 1 and 2 as stable, diamagnetic yellow microcrys-
talline solids, soluble in acetone, dichloromethane and
chloroform. Although other metallic thiolates can be used
successfully to accomplish these reactions, the extremely
low solubility of the resulting lead dichloride affords higher
yields and cleaner products [11].
½MCl2ðdppeÞꢁ þ PbðSRfÞ2 ! ½MðSRfÞ2ðdppeÞꢁ þ PbCl2
ð1Þ
M = Pd, Rf = p-C6F4(CF3) 1a, C6F5 1b, p-C6HF4 1c,
o-C6H4(CF3) 1d
M = Pt, Rf = p-C6F4(CF3) 2a, C6F5 2b, p-C6HF4 2c,
o-C6H4(CF3) 2d
As expected [12], reactions with palladium compounds
left over relatively long reaction times, give rise to red
insoluble powders of [{Pd(SRf)2}n] similar to those
described earlier [13]. In order to minimize the formation
Fig. 1. ORTEP drawing and numbering scheme of [Pd(p-SC6HF4)2-
(dppe)] (1c). Ellipsoids are shown at the 30% probability level.

4278
G. Rivera et al. / Polyhedron 26 (2007) 4276–4286
Table 1
˚
Selected bond distances (A) and angles (°) for [Pd(p-SC6HF4)2(dppe)] (1c),
[Pt(SC6F5)2(dppe)] (2b) and [Pt(o-SC6H4(CF3))2(dppe)] (2d)
[Pd(p-SC6HF4)2(dppe)] (1c)
Pd(1)–P(1)
2.2703(7)
Pd(1)–S(1)
2.3642(7)
P(1)–Pd(1)–P(1)#1
P(1)–Pd(1)–S(1)
S(1)–Pd(1)–S(1)#1
85.07(4)
172.23(3)
100.37(4)
P(1)#1–Pd(1)–S(1)
C(1)–S(1)–Pd(1)
87.29(3)
109.97(9)
[Pt(SC6F5)2(dppe)] (2b)
Pt(1)–P(1)
2.2447(18)
Pt(1)–S(1)
2.3585(17)
P(1)–Pt(1)–P(1)#1
P(1)–Pt(1)–S(1)
C(13)–P(1)–Pt(1)
85.95(13)
172.44(6)
116.5(3)
P(1)#1–Pt(1)–S(1)
C(1)–S(1)–Pt(1)
S(1)–Pt(1)–S(1)#1
87.33(8)
110.4(3)
99.57(2)
[Pt(o-SC6H4(CF3))2(dppe)] (2d)
Molecule 1
Pt(1)–P(1)
Pt(1)–P(2)
2.2611(15)
2.2675(14)
Pt(1)–S(2)
Pt(1)–S(1)
2.3481(16)
2.3604(14)
P(1)–Pt(1)–P(2)
P(2)–Pt(1)–S(2)
P(1)–Pt(1)–S(1)
C(1)–S(1)–Pt(1)
82.21(5)
87.17(5)
85.61(5)
112.0(2)
P(1)–Pt(1)–S(2)
P(2)–Pt(1)–S(1)
S(2)–Pt(1)–S(1)
C(8)–S(2)–Pt(1)
172.17(5)
169.99(5)
102.12(5)
117.3(2)
Molecule 2
Pt(2)–P(52)
Pt(2)–S(52)
Fig. 2. ORTEP drawing and numbering scheme of [Pt(SC6F5)2(dppe)]
(2b). Ellipsoids are shown at the 30% probability level.
2.2494(14)
2.3636(15)
Pt(2)–P(51)
Pt(2)–S(51)
2.2504(15)
2.3685(14)
P(52)–Pt(2)–P(51)
P(51)–Pt(2)–S(51)
P(52)–Pt(2)–S(52)
C(51)–S(51)–Pt(2)
86.13(5)
88.87(5)
88.35(5)
S(52)–Pt(2)–S(51)
P(51)–Pt(2)–S(52)
P(52)–Pt(2)–S(51)
C(58)–S(52)–Pt(2)
97.01(5)
172.53(5)
173.32(5)
108.6(2)
109.98(19)
Symmetry code #1 for 1c and 2b: 1 ꢀ x, y, 1/2 ꢀ z.
2.2. Bimetallic complexes
Dinuclear complexes 3 to 4 were prepared according to
Scheme 1, where the mononuclear complexes 1 and 2 were
used as metalloligands. These compounds were isolated as
air stable yellow microcrystalline solids soluble in acetone,
dichloromethane and chloroform.
2.3. Variable temperature NMR studies
1H, 19F and 31P NMR spectra show the expected mag-
netic systems discussed above for each of the fluorinated
rings. The corresponding parameters are listed in the exper-
imental section. In addition, room temperature 31P NMR
for dinuclear platinum complexes 4, exhibit single absorp-
tions with platinum satellites. Coupling constants 1JPt–P are
larger in dinuclear compounds than in the mononuclear
analogues, as expected if the change from terminal to
bridged sulfur–metal bonds results in stronger metal–phos-
phorus bonds.
Fig. 3. ORTEP drawing and numbering scheme of [Pt(o-SC6H4(CF3))2-
(dppe)] (2d). Ellipsoids are shown at the 30% probability level.
the palladium analogues, 2.3585(17) A for [Pt(SC6F5)2-
We have examined the variable temperature 1H and 19
F
˚
(dppe)] (2b) and 2.3481(16), 2.3604(14), 2.3636(15),
2.3685(14) A for [Pt(o-SC6H4(CF3))2(dppe)] (2d). The
bonding angles in 2b vary between 85.95° and 99.57°
whereas in 2d they vary between 82.21° and 102.12° for
molecule 1 and between 86.13° and 97.01° for molecule 2.
NMR spectra of all compounds 3 and 4. Unfortunately, at
the limiting low temperature (ꢀ90 °C) all spectra of palla-
dium containing compounds show poorly defined, very
broad bands because, as has been reported before [17],
the energy involved for processes on palladium complexes
˚

G. Rivera et al. / Polyhedron 26 (2007) 4276–4286
4279
Ph
Ph
Ph
Ph
P
SO3CF3
SO3CF3
P
Cl
P
+2Ag(SO3CF3)
-2AgCl
M
M
P
Cl
Ph
Ph
Ph
Ph
Ph
Ph
Rf
P
S
S
M = Pd
M = Pt
M
P
Rf = p-C6F4CF3
Rf = C6F5
Rf = p-C6HF4
Rf = o-C6H4CF3
3a
3b
3c
3d
4a
4b
4c
4d
Ph
Ph
Rf
(SO3CF3)2
Ph
Rf
Ph
Ph
Ph
P
P
S
P
M
M
P
S
Ph
Ph
Ph
Ph
Rf
Scheme 1.
is significantly smaller than that observed for platinum
compounds undergoing a similar process. Therefore, the
following discussion is focused on platinum compounds
mainly through the 19F NMR results.
rine), a pseudotriplet at ꢀ148.0 ppm (integral = 2, para-
fluorine) and a multiplet at ꢀ155.8 ppm (integral = 3,
meta-fluorine). As before, none of these signals are modi-
fied by increasing the temperature to 50 °C.
At lower temperatures (Fig. 5) ortho and meta-fluorine
absorptions become broad and in the lowest temperature
limit, the meta-fluorine signal is split into a broad doublet
(ꢀ154.5, ꢀ156.0, Dd = 1.5 ppm) which is also interpreted
as resulting from the restricted rotation of the S–C6F5
The room temperature 19F NMR spectra of the perfluori-
nated compound [Pt2(l-p-SC6F4(CF3))2(dppe)2](SO3CF3)2
(4a) shows four signals: a pseudotriplet at ꢀ56.7 ppm (inte-
gral = 3, C–CF3); a singlet at ꢀ77.4 ppm (integral = 3, S–
CF3); a double set of doublets at ꢀ124.0 ppm (integral = 2,
ortho-fluorine) and a multiplet at ꢀ139.4 ppm (integral = 2,
meta-fluorine). Increasing the temperature from ambient to
50 °C does not affect the spectra.
bond. The calculated free activation energy for this process
¼
is DG = 37.39 0.4 kJ molꢀ1
.
The fact that in 4b the meta-fluorine nuclei absorption is
split instead of the ortho-fluorine band as in 4a, is probably
due to differences in steric requirements between the thio-
late rings and the phosphine benzene substituents which
share a densely occupied space.
Decreasing the experimental temperature down to ca.
ꢀ70 °C (see Fig. 4) broadens both the ortho and the meta
fluorine signals and at ꢀ90 °C the ortho fluorine band is
unfolded into a pair of signals with the same intensity
(ꢀ122.0, ꢀ125.1, Dd 3.1 ppm) although the meta fluorine
absorption remains broad (ꢀ139.30 ppm) and unresolved
at this temperature. On the other hand, the absorption aris-
ing from the para-CF3 group of the thiolate ligands remains
unchanged along the complete low temperature interval.
Since ortho and meta but not the para substituents are
affected at low temperatures, the fluxional process more
likely to be observed in this case is the restricted rotation
The room temperature 19F NMR spectra of [Pt2(l-p-
SC6HF4)2(dppe)2]2+ (4c) exhibits three absorptions: a sin-
glet at ꢀ74.0 ppm (integral = 3, S–CF3), a multiplet at
ꢀ126.7 ppm (integral = 2, ortho-fluorine) and a multiplet
at ꢀ137.6 ppm (integral = 2, meta-fluorine).
High temperature (Fig. 6) 19F NMR experiments with
compound 4c show no changes of the absorptions up to
50 °C. As before, decreasing the temperature results in
broad signals until at ꢀ90 °C the ortho-fluorine absorption
splits into a pair of broad signals (ꢀ125.5, ꢀ126.9,
Dd = 1.4 ppm). Unfortunately, since the experiment does
not reach the point of slow exchange, the free activation
energy cannot be calculated with a reliable accuracy.
Compound [Pt2(l-o-SC6H4(CF3))2(dppe)2]2+ (4d), with
no fluorine atoms on the S-phenyl rings have the less elec-
tronegative, more basic thiolate ligand, among the com-
pounds studied here. Having an ortho CF3 group, these
of the sulfur–carbon bonds. The calculated free activation
¼
energy for this process is DG = 38.71 0.3 kJ molꢀ1
,
which is ca. 3 kJ molꢀ1 lower than the average found for
bimetallic complexes of the type [Pt2(l-SR)2(SR)4](NBu4)2
[18].
As expected, the room temperature 19F NMR spectrum
of [Pt2(l-SC6F5)2(dppe)2](SO3CF3)2 (4b), shows four sig-
nals: a singlet at ꢀ77.8 ppm (integral = 3, S–CF3); a double
set of doublets at ꢀ122.2 ppm (integral = 2, ortho-fluo-

4280
G. Rivera et al. / Polyhedron 26 (2007) 4276–4286
CF3
F
F
F
F
P
P
P
P
S
S
Pt
Pt
(SO3CF3)
2
F
F
F
F
CF3
+50°C
+25°C
+10°C
-10°C
-20°C
-30°C
-40°C
-50°C
-60°C
-70°C
-90°C
orto
meta
-137.000
-100°C
-121.000
-125.000
-129.000
-133.000
-141.00 ppm
Fig. 4. Variable temperature 19F NMR spectra (ortho and meta thiolate ligand signals) of [Pt2(l-p-SC6F4(CF3))2(dppe)2](SO3CF3)2 (4a).
F
F
F
F
F
P
P
P
P
S
S
Pt
Pt
(SO3CF3)2
F
F
F
F
F
+50°C
+25°C
-30°C
-50°C
-60°C
-70°C
-80°C
-90°C
-100°C
orto
-122.000
para
-130.000 -134.000 -138.000 -142.000 -146.000
meta
-150.000 -154.000
-110°C
-158.000 ppm
-126.000
Fig. 5. Variable temperature 19F NMR spectra showing the thiolate region of [Pt2(l-SC6F5)2(dppe)2](SO3CF3)2 (4b).
thiolate ligands are asymmetric. The orientation of these
substituents relative to the Pt–S2–Pt ring defines the iso-
mers cis and trans as shown in Scheme 2.
At room temperature the 19F NMR spectra of 4d exhibit
a pair of singlets at ꢀ57.5 ppm (integral = 1) arising from
the thiolate–CF3 and at ꢀ79.1 ppm (integral = 1) from

G. Rivera et al. / Polyhedron 26 (2007) 4276–4286
4281
H
F
F
F
F
P
P
S
S
P
P
(SO3CF3)2
Pt
Pt
F
F
F
F
50°C
30°C
10°C
0°C
-10°C
H
-20°C
-30°C
-40°C
-60°C
-70°C
-80°C
orto
-129.000
meta
-90°C
-139.000
-135.000
-121.000
-123.000
-125.000
-127.000
-131.000
-133.000
-137.000
Fig. 6. Variable temperature 19F NMR spectra showing the thiolate region of [Pt2(l-p-SC6HF4)2(dppe)2](SO3CF3)2 (4c).
CF3
Although a sulfur inversion process cannot be com-
pletely discarded for this complex [19,20], it seems unlikely
considering that the NMR evidence is consistent along the
CF3
CF3
Pt
Pt
S
S
S
S
¼
series studied here and that the calculated DG is nearly
Pt
Pt
17 kJ molꢀ1 lower than the energy for complexes exhibiting
F3C
sulfur inversion [18].
Trans
Cis
Scheme 2.
2.4. Crystal and molecular structure
1
the triflate–CF3. H NMR spectra are also clearly defined
showing an ABB0C magnetic system for the o-SC6H4CF3
substituents.
Fig. 8 shows the molecular structure of [Pt2(l-o-
SC6H4(CF3))2(dppe)2](SO3CF3)2 4d and main bond dis-
tances and angles are collected in Table 2. This compound
has a centrosymmetric square-planar [Pt2(l-SR)2] core.
The crystallographic isomer stabilized in the solid state
has the anti configuration with the substituents on the
bridging thiolate ligands pointing towards opposite direc-
tions. The trifluoromethyl groups in ortho positions at the
thiolate rings are also pointing in opposite, trans, directions.
The thiolate C6H4CF3 ring and two phenyl rings of neigh-
boring phosphines are aligned in an almost coplanar fash-
ion, allowing strong intra-cation p–p interactions, with
centroid to centroid separations in the range 3.526–
Increasing the temperature to 50 °C has no noticeable
effect on the 19F NMR spectra of 4d, Fig. 7, but upon low-
ering the temperature, the singlet that is initially centered at
d ꢀ57.5 ppm broadens and eventually collapses at ꢀ90 °C
giving rise to two broad bands centered at ꢀ58.1 and
ꢀ58.6 ppm. The intensity of the downfield signal is ca. 11
times larger than that of the upfield absorption. Proton
NMR signals undergo a similar broadening and collapsing
as the temperature is lowered.
The 19F NMR spectral data are consistent with the
rapid interconversion of both cis and trans isomers at high
temperatures and with C–S restricted rotation at low tem-
peratures. Under these conditions the population of each
isomer, in solution, is different (1:11), and it is assumed,
on steric grounds, that the more intense downfield absorp-
tion corresponds to the anti isomer as has been found in the
solid state (vide infra).
˚
3.568 A. As expected, the bridging Pt–S bond distances
(2.3759(10) and 2.3749(10)) are longer than the correspond-
˚
ing terminal Pt–S bond distances (2.36 A, mean) in the
monometallic complex [Pt(o-SC6H4(CF3))2(dppe)] (vide
supra) and longer than the bridging Pt–SR bond lengths
(2.316 A, mean) in compounds [Pt2(l-SR)2(SR)4]2+, proba-
˚
bly reflecting the different trans influence of the dppe ligand
as compared with that of the thiolate ligand. The Pt–S bond
lengths trans to phosphine compare with published values
The calculated free activation energy for this process is
DG = 40.1 0.6 kJ molꢀ1
.
¼

4282
G. Rivera et al. / Polyhedron 26 (2007) 4276–4286
50°C
40°C
25°C
0°C
-20°C
-50°C
F3
C
P
P
S
S
P
P
-60°C
-70°C
(SO3CF3)2
Pt
Pt
CF3
-80°C
-90°C
-57.200
-57.400
-57.600
-57.800
-58.000
-58.200
-58.400
-58.600
-58.800
-59.000
Fig. 7. Variable temperature 19F NMR showing the thiolate–CF3 region of [Pt2(l-o-SC6H4(CF3))2(dppe)2](SO3CF3)2 (4d).
Fig. 8. ORTEP drawing and numbering scheme of [Pt2(l-o-SC6H4(CF3))2(dppe)2](SO3CF3)2 (4d). Ellipsoids are shown at the 30% probability level.
Table 2
3. Conclusions
˚
Main bond distances (A) and angles (°) of the complex [Pt2(l-o-SC6H4-
(CF3))2(dppe)2](SO3CF3)2 (4d)
Homobimetalic, fluorothiolate bridged compounds of
Pt(1)–P(1)
Pt(1)–P(2)
2.2722(10)
2.2709(10)
Pt(1)–S(1)
Pt(1)–S(1)#1
2.3759(10)
2.3749(10)
Pd and Pt, [M2(l-SRf)2(dppe)2], can conveniently be pre-
pared by reacting the metalloligands [M(SRf)2(dppe)] with
the solvato-complexes [M(SO3CF3)2(dppe)].
P(2)–Pt(1)–P(1)
P(2)–Pt(1)–S(1)#1
S(1)#1–Pt(1)–S(1)
P(2)–Pt(1)–S(1)
84.55(4)
172.62(4)
80.03(4)
97.54(4)
Pt(1)#1–S(1)–Pt(1)
P(1)–Pt(1)–S(1)#1
C(1)–S(1)–Pt(1)
P(1)–Pt(1)–S(1)
99.97(4)
98.68(4)
110.98(14)
173.22(4)
In contrast with the behavior of the monometallic com-
pounds included in this study, all members of the bimetallic
series of [M2(l-SRf)2(dppe)2]2+ complexes are fluxional on
the NMR time scale when they are in solution. The avail-
able data suggest that the nature of the process is common
to all examples. Thus the ligands p-SC6F4(CF3), SC6F5,
p-SC6HF4 and o-SC6H4(CF3) on complexes [M2(l-SRf)2-
(dppe)2]2+, are involved in hindered C–S bond rotation
Symmetry code #1: 2 ꢀ x, ꢀy, 1 ꢀ z.
for dinuclear compounds with thiolate ligands [21–23]. The
˚
Ptꢂ ꢂ ꢂPt distance, 3.6386(3) A, is rather long, and any possi-
bility of direct magnetic interaction may be ruled out.

G. Rivera et al. / Polyhedron 26 (2007) 4276–4286
4283
processes. Apparently, the possible rotamers experience
different steric interactions, therefore, ortho-fluorine atoms
are specially affected for p-SC6F4(CF3) and p-SC6HF4 con-
taining compounds, meta-fluorine atoms are rendered dis-
tinct for the compound with SC6F5 bridging ligands
whereas o-SC6H4(CF3), which is intrinsically asymmetric,
defines cis and trans isomers.
The structure of the bimetallic complex studied bears a
square-planar [M2(l-SRf)2] ring with sulfur substituents
pointing towards opposite sites of the plane in an anti
configuration.
4.3.1. [Pd(p-SC6F4(CF3))2(dppe)] (1a)
M.p. 192–194 °C. Anal. Calc. for C40H24F14P2PdS2: C,
47.90; H, 2.41; S, 6.39. Found: C, 47.8; H, 2.5; S, 6.6%.
IR (cmꢀ1): 3055w, 3029w, 1642m, 1471vs, 1436s, 1383m,
1323vs, 1167s, 1133s, 1102m, 998m, 971s, 878w, 830s,
746w, 713s, 690s, 651w, 530m, 478m. 1H NMR
(C2D6CO, 298 K): 7.9, 7.6 (m, 20H, phenyl from phos-
phine), 2.9 (m, 4H, CH2–CH2). 31P NMR (C2D6CO,
298 K): 62.6. 19F NMR (C2D6CO, 298 K): ꢀ129.1 (pd,
o-F), ꢀ143.3 (m, m-F), ꢀ52.6 (t, p-CF3).
4.3.2. [Pd(o-SC6H4(CF3))2(dppe)] (1d)
4. Experimental
M.p. 212–214 °C. Anal. Calc. for C40H32F6P2PdS2: C,
55.92; H, 3.75; S, 7.46. Found: C, 56.7; H, 4.0; S, 6.8%.
IR (cmꢀ1): 3424m, 3055w, 2925w, 1676w, 1637w, 1588m,
1559w, 1483w, 1460w, 1434s, 1310vs, 1245m, 1156s,
1124vs, 1102vs, 1042s, 1029s, 999w, 876w, 817w, 751m,
702s, 689s, 646w, 597w, 529vs, 481m. 1H NMR
(C2D6CO, 298 K): 7.1 (m, o-H, thiolate), 7.6, 6.7 (m, m-
H, thiolate), 6.7 (m, p-H, thiolate), 7.8, 7.5 (m, 20H, phenyl
from phosphine), 2.7 (m, 4H, CH2–CH2). 31P NMR
(C2D6CO, 298 K): 57.1. 19F NMR (C2D6CO, 298 K):
ꢀ62.4 (pt, o-CF3).
4.1. Materials
All reactions were carried out under a dry, oxygen-free
N2 atmosphere, using Schlenk techniques. Solvents were
dried and degassed prior to use, using standard techniques
[24]. All reagents were purchased from Aldrich Chem. Co.
and used as received. [PdCl2(dppe)] [25], [PtCl2(dppe)] [25],
Pb(SRf)2 [26], [Pd(SC6F5)2(dppe)] [15,27] (1b), [Pd(p-
SC6HF4)2(dppe)] [16] (1c), [Pt(SC6F5)2(dppe)] [15,27] (2b)
and [Pt(p-SC6HF4)2(dppe)] [16] (2c) were prepared by pub-
lished methods.
4.4. [Pt(SRf)2(dppe)] complexes 2
4.2. Instruments
A solution of 0.211 mmol of Pb(SRf)2 in acetone
(10 mL) was added to a suspension of 0.211 mmol of
[PtCl2(dppe)] in acetone (10 mL). The reaction was mag-
netically stirred for 24 h at room temperature. The PbCl2
precipitated was separated by filtration through silica gel
and the solution evaporated to yield a yellow powder which
was recrystallized from acetone.
Microanalyses were performed using a Fisons EA1108
instrument. FT-IR spectra were recorded over the 4000–
200 cmꢀ1 range on a Perkin–Elmer 1600 spectrophotome-
ter with samples prepared as CsI pellets. Data are
expressed in wavenumbers (cmꢀ1) with relative intensities
(vs = very strong, s = strong, m = medium, w = weak).
1H, 19F and 31P NMR spectra were measured with a
Varian spectrometer operating at 299.7, 282.0 and
121.5 MHz respectively. Chemical shifts are relative to
TMS (d = 0 (1H)), CFCl3 (d = 0 (19F)) and H3PO4/D2O
(d = 0 (31P)). A standard variable temperature unit was
used to control the probe were within 1 °C. Complexes
were dissolved in deuterated acetone. FAB mass spectra
were obtained on a JEOL JMS-SX102A.
4.4.1. [Pt(p-SC6F4(CF3))2(dppe)] (2a)
Yield: 90.7%, m.p. 212–214 °C. Anal. Calc. for
C40H24F14P2PtS2: C, 44.01; H, 2.22; S, 5.87. Found: C,
44.1; H, 2.2; S, 5.6%. IR (cmꢀ1): 3433w, 3055w, 1642m,
1471vs, 1437m, 1384m, 1324vs, 1168s, 1130s, 1103m,
998w, 972vs, 880w, 750w, 713s, 690s, 653w, 532s, 483m.
1H NMR (C2D6CO, 298 K): 8.0, 7.6 (m, 20H, phenyl from
phosphine), 2.8 (m, 4H, CH2-CH2). 31P NMR (C2D6CO,
298 K): 52.3 (JPt–P = 3033. Hz). 19F NMR (C2D6CO,
298 K): ꢀ132.9 (pd, o-F), ꢀ147.2 (m, m-F), ꢀ56.9 (t, p-
CF3).
All variable temperature NMR experiments were carried
out in deuterated acetone. The activation parameters for
dynamic processes were calculated from simulation spectra
[28] and the Eyring equation using curve fitting techniques
[29–31].
4.4.2. [Pt(o-SC6H4(CF3))2(dppe)] (2d)
4.3. [Pd(SRf)2(dppe)] complexes 1
Yield: 84.63%, m.p. 197–199 °C. Anal. Calc. for
C40H32F6P2PtS2: C, 50.69; H, 3.40; S, 6.76. Found: C,
50.8; H, 3.5; S, 6.5%. IR (cmꢀ1): 3434w, 3052w, 1710w,
1558w, 1483w, 1461m, 1435vs, 1308vs, 1246s, 1167vs,
1121vs, 1104vs, 1042s, 1029vs, 997m, 878w, 824m, 754s,
715s, 702s, 691s, 655w, 645m, 532vs, 496w, 480m, 461m,
432w, 157m. 1H NMR (C2D6CO, 298 K): 7.1 (m, o-H,
thiolate), 7.7, 6.8 (m, m-H, thiolate), 6.8 (m, p-H, thiolate),
8.0, 7.5 (m, 20H, phenyl from phosphine), 2.7 (m, 4H,
A solution of 0.348 mmol of Pb(SRf)2 in acetone
(15 mL) was added slowly to a solution of 0.348 mmol of
[PdCl2(dppe)] in acetone (10 mL). The reaction was mag-
netically stirred for 15 min at room temperature and the
white PbCl2 precipitated filtered off. The yellow product
was purified by column chromatography with silica gel,
using acetone/hexanes (1:2) as eluent.

4284
G. Rivera et al. / Polyhedron 26 (2007) 4276–4286
CH2–CH2). 31P NMR (C2D6CO, 298 K): 50.3 (JPt–P
=
1103s, 1029vs, 998m, 880w, 818w, 749m, 704m, 690s,
636vs, 572w, 530s, 482m.1H NMR (C2D6CO, 298 K): 7.2
(m, o-H, thiolate); 8.2, 7.0 (m, m-H, thiolate); 7.0 (m, p-
H, thiolate), 7.6, 7.4 (m, 20H, phenyl from phosphine),
2.6 (m, 4H, CH2–CH2). 31P NMR (C2D6CO, 298 K):
65.7. 19F NMR (C2D6CO, 298 K): ꢀ53.7 (pt, o-CF3),
ꢀ73.8 (s, SO3CF3).
2879 Hz). 19F NMR (C2D6CO, 298 K): ꢀ68.3 (pt, o-CF3).
4.5. [Pd(l-SRf)(dppe)]2(SO3CF3)2 complexes (3)
A solution of 0.139 mmol of AgSO3CF3 in 10 mL of
acetone was added to a solution of 0.07 mmol of
[PdCl2(dppe)] in acetone (15 mL) and stirred for 24 h at
room temperature. After filtration trough Celite,
0.07 mmol of [Pd(SRf)2(dppe)] in 15 mL of acetone were
added and stirred for 7 h. The reaction was followed by
TLC until completeness. Slow evaporation of the solvent
yield a yellow powder which was recrystallized from diffu-
sion of hexanes in acetone.
4.6. [Pt(l-SRf)(dppe)]2(SO3CF3)2 complexes 4
A solution of 0.1506 mmol of AgSO3CF3 in 10 mL of
acetone was added to a solution of 0.0753 mmol of
[PtCl2(dppe)] in acetone (15 mL) and stirred for 24 h at
room temperature. After filtration trough Celite,
0.0753 mmol of [Pt(SRf)2(dppe)] in 15 mL of acetone were
added and stirred for 7 h. The reaction was followed by
TLC until completeness. Slow evaporation of the solvent
yield a yellow powder which was recrystallized from diffu-
sion of hexanes in acetone.
4.5.1. [Pd(l-p-SC6F4(CF3))(dppe)]2(SO3CF3)2 (3a)
M.p. 168–170 °C. Anal. Calc. for C68H48F20O6P4Pd2S4:
C, 45.22; H, 2.68; S, 7.10. Found: C, 45.0; H, 2.8; S,
7.3%. IR (cmꢀ1): 3439w, 3058w, 2918w, 1643m, 1586w,
1479vs, 1437s, 1325vs, 1257vs, 1224m, 1144s, 1102m,
1029s, 997w, 978s, 942w, 881w, 825m, 749m, 714s, 690s,
656w, 637s, 531s, 480m, 437w. 1H NMR (C2D6CO,
298 K): 7.7, 7.6 (m, 20H, phenyl from phosphine), 2.9
(m, 4H, CH2–CH2). 31P NMR (C2D6CO, 298 K): 74.7.
19F NMR (C2D6CO, 298 K): ꢀ122.1(pd, o-F), ꢀ138.4
(m, m-F), ꢀ54.4 (t, p-F), ꢀ76.4 (s, SO3CF3).
4.6.1. [Pt(l-p-SC6F4(CF3))(dppe)]2(SO3CF3)2 (4a)
M.p. 235–237 °C. Anal. Calc. for C68H48F20O6P4Pt2S4:
C, 41.17; H, 2.44; S, 6.45. Found: C, 41.6; H, 2.5; S,
6.4%. IR (cmꢀ1): 3480w, 3058w, 1707w, 1643m, 1480vs,
1437s, 1326vs, 1257vs, 1224s, 1144vs, 1105s, 1030vs,
997m, 979vs, 823s, 750m, 714vs, 691s, 637vs, 572m,
534vs, 485s. 1H NMR (C2D6CO, 298 K): 7.7, 7.6 (m,
20H, phenyl from phosphine), 2.7 (m, 4H, CH2–CH2).
31P NMR (C2D6CO, 298 K): 52.8 (JPt–P = 3122 Hz). 19F
NMR (C2D6CO, 298 K): ꢀ122.8 (pd, o-F), ꢀ138.2 (m,
m-F), ꢀ55.6 (t, p-CF3), ꢀ77.4 (s, SO3CF3).
4.5.2. [Pd(l-SC6F5)(dppe)]2(SO3CF3)2 (3b)
Yield: 70.14%. M.p. 200–201 °C and at 210 °C decom-
position. Anal. Calc. for C66H48F16O6P4Pd2S4: C, 46.48;
H, 2.84; S, 7.51. Found: C, 46.0; H, 2.9; S, 7.3%. IR
(cmꢀ1): 3462s, 3059w, 1639w, 1513vs, 1484vs, 1437s,
1276vs, 1258vs, 1223s, 1159s, 1102s, 1083s, 1031vs, 997m,
977s, 877w, 853m, 816m, 754m, 721s, 707m, 690s, 637vs,
573m, 531vs, 480s, 432m. 1H NMR (C2D6CO, 298 K):
7.7, 7.6 (m, 20H, phenyl from phosphine), 2.8 (m, 4H,
CH2–CH2). 31P NMR (C2D6CO, 298 K): 68.9. 19F NMR
(C2D6CO, 298 K): ꢀ125.5 (pd, o-F), ꢀ160.1 (m, m-F),
ꢀ153.5 (pt, p-F), ꢀ77.4 (s, SO3CF3).
4.6.2. [Pt(l-SC6F5)(dppe)]2(SO3CF3)2 (4b)
M.p. 240–242 °C. Anal. Calc. for C66H48F16O6P4Pt2S4:
C, 42.08; H, 2.57; S, 6.80. Found: C, 42.7; H, 2.7; S,
6.5%. IR (cmꢀ1): 3462m, 3057w, 1708w, 1637w, 1513s,
1488vs, 1437s, 1261vs, 1223m, 1156s, 1104s, 1087s,
1030vs, 997w, 979s, 882w, 853m, 820w, 752m, 720m,
691s, 637s, 572w, 533vs, 485m. 1H NMR (C2D6CO,
298 K): 7.7, 7.6 (m, 20H, phenyl from phosphine), 2.7
(m, 4H, CH2–CH2). 31P NMR (C2D6CO, 298 K): 52.3
(JPt–P = 3097 Hz). 19F NMR (C2D6CO, 298 K): ꢀ125.5
(pd, o-F), ꢀ159.2 (m, m-F), -151.3 (pt, p-F), ꢀ77.3 (s,
SO3CF3).
4.5.3. [Pd(l-p-SC6HF4)(dppe)]2(SO3CF3)2 (3c)
M.p. 247–29 °C. Anal. Calc. for C66H50F14O6P4Pd2S4:
C, 47.48; H, 3.02; S, 7.67. Found: C, 48.6; H, 3.2; S,
7.4%. IR (cmꢀ1): 3501w, 3056m, 2961w, 1628w, 1490vs,
1436s, 1279vs, 1223s, 1156s, 1103s, 1029vs, 915s, 878m,
817m, 753m, 721s, 708s, 668s, 637vs, 532vs, 477m. 1H
NMR (C2D6CO, 298 K): 7.12 (m, p-H, thiolate), 7.7, 7.5
(m, 20H, phenyl from phosphine), 2.8 (m, 4H, CH2–
CH2). 31P NMR (C2D6CO, 298 K): 67.8. 19F NMR
(C2D6CO, 298 K): ꢀ122.5 (pd, o-F), ꢀ134.2 (m, m-F),
ꢀ74.0 (s, SO3CF3).
4.6.3. [Pt(l-p-SC6HF4)(dppe)]2(SO3CF3)2 (4c)
Yield: 77.16%. M.p. 275–277 °C. Anal. Calc. for
C66H50F14O6P4Pt2S4: C, 42.90; H, 2.73; S, 6.93. Found:
C, 43.2; H, 2.8; S, 6.8%. IR (cmꢀ1): 3435m, 3066w,
1629w, 1491vs, 1437s, 1377w, 1265vs, 1223m, 1155s,
1105s, 1030s, 997w, 916m, 881w, 820w, 752m, 708s, 690s,
1
637s, 572w, 534s, 483m. H NMR (C2D6CO, 298 K): 7.1
4.5.4. [Pd(l-o-SC6H4(CF3))(dppe)]2(SO3CF3)2 (3d)
Yield: 60.57%. M.p. 227–229 °C. Anal. Calc. for
C68H56F12O6P4Pd2S4: C, 49.16; H, 3.40; S, 7.70. Found:
C, 48.3; H, 3.6; S, 7.6%. IR (cmꢀ1): 3432m, 3056w,
1587w, 1483w, 1436s, 1311vs, 1259vs, 1223m, 1159vs,
(m, p-H, thiolate), 7.7, 7.6 (m, 20H, phenyl from phos-
phine), 2.68 (m, 4H, CH2–CH2). 31P NMR (C2D6CO,
298 K): 52.2 (JPt–P = 3097 Hz). 19F NMR (C2D6CO,
298 K): ꢀ122.5 (pd, o-F), ꢀ133.3 (m, m-F), ꢀ74.0 (s,
SO3CF3).

G. Rivera et al. / Polyhedron 26 (2007) 4276–4286
4285
Table 3
Crystallographic data for complexes 1c, 2b, 2d, and 4d
1c
2b
2d
4d
C38H26F8P2PdS2
867.05
C38H24F10P2PtS2
991.72
C40H32F6P2PtS2
947.81
C66H56F6P4Pt2S2 (C2F6O6S2)
1839.43
Mw
ꢀ
ꢀ
Space group
C2/c
C2/c
P1
P1
˚
a (A)
18.7885(11)
12.7777(9)
15.8106(10)
18.6304(18)
12.9706(10)
16.1175(17)
11.9449(7)
15.8927(9)
20.4850(11)
80.169(4)
88.371(5)
77.507(4)
3740.8(4)
4
11.4866(8)
12.9775(9)
13.3213(10)
116.085(6)
95.255(6)
99.240(4)
1730.6(2)
1
˚
b (A)
˚
c (A)
a (°)
b (°)
c (°)
107.295(5)
109.585(8)
3
˚
V (A )
3624.1(4)
4
0.785
3669.4(6)
4
4.104
Z
l (mmꢀ1
)
4.007
1.683
4.334
1.765
qcalc (g cmꢀ3
)
1.589
1.795
Temperature (K)
300(2)
297(2)
299(2)
0.71073
R1 = 3.77,
wR2 = 7.70
R1 = 6.18,
wR2 = 8.52
299(2)
0.71073
R1 = 3.31,
wR2 = 8.21
R1 = 4.06,
wR2 = 8.61
˚
k (A)
0.71073
R1 = 2.92,
wR2 = 6.67
R1 = 4.01,
0.71073
R1 = 4.01,
wR2 = 10.60
R1 = 6.61,
wR2 = 12.02
R indices (I < 2r(1))a (%)
R indices (all data)a (%)
wR2 = 7.13
P
P
P
P
a
R(Fo) = iFoj ꢀ jFcj/ jFoi, Rw(F2o) = ( w(jFoj ꢀ jFcj)2/ wFo2)1/2
.
4.6.4. [Pt(l-o-SC6H4(CF3))(dppe)]2(SO3CF3)2 (4d)
as a CIF, and raw data, as structure factors, are available
on request to authors.
Yield: 54.72%. M.p. 267–269 °C. Anal. Calc. for
C68H56F12O6P4S4Pt2: C, 44.39; H, 3.07; S, 6.96. Found:
C, 45.0; H, 3.1; S, 6.8%. IR (cmꢀ1): 3515w, 3054w,
2963w, 1707w, 1586w, 1572w, 1482m, 1437vs, 1309vs,
1259vs, 1222s, 1153vs, 1139vs, 1103vs, 1028vs, 997s,
887m, 828m, 753s, 713s, 687s, 660m, 636vs, 595w, 571w,
Acknowledgements
We thank Mr. Francisco Irby for his helpful assistance.
We are grateful to DGAPA-UNAM (IN119305) and
CONACYT (44494) for financial support of this research.
1
534vs, 516m, 445m. H NMR (C2D6CO, 298 K): 7.0 (m,
o-H, thiolate); 8.4, 7.3 (m, m-H, thiolate); 7.3 (m, p-H, thio-
late), 7.7, 7.5 (m, 20H, phenyl from phosphine), 2.5 (m, 4H,
Appendix A. Supplementary material
CH2–CH2). 31P NMR (C2D6CO, 298 K): 54.4 (JPt–P
=
3117 Hz). 19F NMR (C2D6CO, 298 K): ꢀ58.5 (pt, o-CF3),
CCDC 626895, 626896, 626897 and 626898 contain the
supplementary crystallographic data for 1c, 2b, 2d and 4d.
These data can be obtained free of charge via http://
www.ccdc.cam.ac.uk/conts/retrieving.html, or from the
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or
e-mail: deposit@ccdc.cam.ac.uk. Supplementary data asso-
ciated with this article can be found, in the online version,
at doi:10.1016/j.poly.2007.05.025.
ꢀ79.1 (s, SO3CF3).
4.7. X-ray diffraction data
Suitable single crystals of complexes 1c, 2b, 2d and 4d
were obtained by slow evaporation of acetone solutions
and were found to be stable in air. Pertinent crystal data
and other crystallographic parameters are listed in Table
3. The diffraction data were collected on a Bruker P4 dif-
fractometer [32] using graphite monochromated Mo Ka
References
˚
radiation (k = 0.71073 A) and h/2h or x scan mode with
[1] V.K. Jain, L. Jain, Coord. Chem. Rev. 249 (2005) 3075.
[2] J.P. Blower, J.R. Dilworth, Coord. Chem. Rev. 76 (1987) 121.
variable scan speed. Absorption corrections were applied
using w-scans.
´
´
´
[3] J.J. Garcıa, A. Arevalo, V. Montiel, F. del Rıo, B. Quiroz, H. Adams,
For all four complexes non-H atoms were refined aniso-
tropically and H atoms were placed in idealized positions
[33]. In the case of 2b, C and F atoms were restrained so
that their Uij components approximate to isotropic behav-
ior. In the case of 4d, the triflate ion was restrained to con-
verge to a sensible geometry, through suitable restraints on
bond lengths.
P.M. Maitlis, Organometallics 16 (1997) 3216.
[4] D. Sellmann, A. Hille, F.W. Heinemam, M. Moll, A. Ro¨sler, J.
Sutter, G. Brehm, M. Reiher, B.A. Hess, S. Schneider, Inorg. Chim.
Acta 348 (2003) 194.
[5] B. Krebs, G. Henkel, Angew. Chem., Int. Ed. Engl. 30 (1991) 769.
´
´
[6] J.C. Bayon, C. Claver, A.M. Masdeu-Bulto, Coord. Chem. Rev. 193–
195 (1999) 73.
[7] (a) H.C. Clark, V.K. Jain, G.S. Rao, J. Organomet. Chem. 279 (1985)
Selected geometric parameters for 1c, 2b, 2d and 4d are
listed in Tables 2 and 3. Complete data have been deposited
181;
(b) V.K. Jain, G.S. Rao, Inorg. Chim. Acta 127 (1987) 161;

4286
(c) M.L. Clarke, Polyhedron 20 (2001) 151;
G. Rivera et al. / Polyhedron 26 (2007) 4276–4286
[22] V.K. Jain, S. Kannan, R.J. Butcher, J.P. Jasinski, J. Organomet.
´
(d) G.B. Karet, N.M. Kostic, Inorg. Chem. 37 (1998) 1021.
Chem. 468 (1994) 285.
[8] H.C. Clark, V.K. Jain, G.S. Rao, J. Organomet. Chem. 279 (1985)
181.
[23] M.C. Hall, J.A. Jarvis, B.T. Kilbourn, P.G. Owston, J. Chem. Soc.,
Dalton Trans. (1972) 1544.
[9] H. Torrens, Coord. Chem. Rev. 196 (2000) 331.
[10] (a) R. Salcedo, H. Torrens, Transition Met. Chem. 5 (1980) 247;
(b) L. Villanueva, M. Arroyo, S. Bernes, H. Torrens, Chem.
Commun. (2004) 1942.
[11] (a) M. Capdevila, W. Clegg, P. Gonzalez-Duarte, B. Harris, I. Mira,
J. Sola, I.C. Taylor, J. Chem. Soc., Dalton Trans. (1992) 2817;
(b) A. Singhal, V.K. Jain, B. Varghese, E.R.T. Tiekink, Inorg. Chim.
Acta 285 (1999) 190.
[12] D.M. Roundhill, in: G. Wilkinson (Ed.), Comprehensive Coordina-
tion Chemistry, Pergamon Press, Oxford, 1987, p. 351.
[13] W. Beck, K.M. Stetter, S. Tadros, K.E. Shwarzhaus, Chem. Ber. 100
(1967) 3944.
[24] (a) D.D. Perrin, W.L.F. Armarego, Purification of Laboratory
Chemicals, third ed., Pergamon Press, 1988;
(b) J.A. Riddick, T.K. Sakaro, Organic Solvents: Physical properties
and Methods of Purification, Techniques of Chemistry, fourth ed.,
vol. II, Wiley Interscience, NY, 1970.
[25] (a) T.G. Appleton, M.A. Bennett, J.B. Tomkins, J. Chem. Soc.,
Dalton Trans. (1976) 439;
(b) M.P. Brown, R.J. Puddephatt, M. Rashidi, K.R. Seddon, J.
Chem. Soc., Dalton (1977) 951.
[26] (a) M.E. Peach, Can. J. Chem. 46 (1968) 2699;
´
´
(b) V.A. Bertran, A.J. Garcıa, E. Martin, P. Sosa, H. Torrens, Rev.
´
´
Soc. Quım. Mex. 37 (1993) 185.
´
´
´
[14] G. Wei, H. Liu, Acta Crystallogr., Sect. C 46 (1990) 2457.
[15] A. Singhal, V.K. Jain, B. Varghese, E.R.T. Tiekink, Inorg. Chim.
Acta 285 (1999) 190.
[27] R. Uson, J. Fornies, M.A. Uson, S. Herrero, J. Organomet. Chem.
447 (1993) 137.
[28] P.H.M. Budzelaar, gNMR-3.6, Cherwell Scientific Publishing Lim-
ited, Oxford, UK, 1995.
´
[16] M.A. Uson, J.M. Llanos, J. Organomet. Chem. 663 (2002) 98.
[17] E.W. Abel, S.K. Bhargava, K.G. Orrell, Prog. Inorg. Chem. 32 (1984)
1.
[29] J. Sandstro¨m, Dynamic NMR Spectroscopy, Academic Press, New
York, 1982.
`
´
´
[18] G. Rivera, S. Bernes, C. Rodrıguez de Barbarın, H. Torrens, Inorg.
[30] H. Friebolin, Basic One and Two Dimensional NMR Spectroscopy,
VCH Publishers, New York, 1995.
Chem. 40 (2001) 5575.
[19] S.S. Oster, W.D. Jones, Inorg. Chim. Acta 357 (2004) 1836.
[20] E.W. Abel, G.W. Farrow, K.G. Orrell, V. Sik, J. Chem. Soc., Dalton
(1977) 42.
[31] K.G. Orrell, Coord. Chem. Rev. 96 (1989) 1.
[32] J. Fait, XSCANS Users Manual, Siemens Analytical X-ray Instruments
Inc., Madison, WI, 1991.
[21] E.W. Abel, D.G. Evans, J.R. Koe, M.B. Hursthouse, M. Mazid, M.F.
Mahon, K.C. Molloy, J. Chem. Soc., Dalton Trans. (1990) 1697.
[33] G.M. Sheldrick, SHELX97 Users Manual, University of Go¨ttingen,
Go¨ttingen, Germany, 1997.