[1,1′-Bis(diphenylphosphino)ferrocene]palladium(II) complexes with fluorinated benzenethiolate ligands: Examination of the electronic effects in the solid state, solution and in the Pd-catalyzed Heck reaction with the catalytic system [Pd(dppf)(SRF)2]

Article abstract of DOI:10.1016/j.jorganchem.2004.04.035

A series of palladium thiolate complexes of the type [Pd(dppf) (SR_F)₂] have been synthesized in good yields by metathetical reactions of [Pd(dppf)Cl₂] with [Pb(SR_F)₂], (SR_F=^- SC₆F₅, ^-SC₆F₄ -4-H, ^-SC₆H₄-2-CF₃, ^-SC₆H₄-4-F, ^- SC₆H₄-3-F) and their crystal structures determined. The effect of the different thiolates in the structural properties of the complexes both in the solid state and in solution have been analyzed. Heck coupling reactions were carried out using the complexes [Pd(dppf)(SR_F)₂], SR_F =^-SC₆F₅ (1), ^-SC₆ F₄-4-H (2), ^-SC₆H₄ -2-CF₃ (3), ^-SC₆H₄-4-F (4), ^-SC₆H₄-3-F (5) as catalysts in order to examine both the effect of the thiolates and the P-Pd-P bite angles in the reaction of bromobenzene and styrene. The results obtained indicate that electron-withdrawing substituents may favor higher yields in the Pd catalyzed Heck reaction using [Pd(dppf)(SR_F) ₂] as catalysts.

Full text of DOI:10.1016/j.jorganchem.2004.04.035

Journal of Organometallic Chemistry 689 (2004) 2464–2472
www.elsevier.com/locate/jorganchem
[1,10-Bis(diphenylphosphino)ferrocene]palladium(II) complexes
with fluorinated benzenethiolate ligands: examination of
the electronic effects in the solid state, solution and in the
Pd-catalyzed Heck reaction with the catalytic
system [Pd(dppf)(SRF)2] q
a
Cesar Herrera-Alvarez , Valente Gomez-Benıtez , Rocıo Redon , Juventino J. Garcıa ,
a
b
c
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
Simon Hernandez-Ortega , Ruben A. Toscano , David Morales-Morales
ꢀ
a
a
a,
*
ꢀ
ꢀ
ꢀ
a
Instituto de Quꢀımica, Universidad Nacional Autꢀonoma de Mꢀexico, Cd. Universitaria, Circuito Exterior, Coyoacꢀan, 04510 Mꢀexico City DF, Mꢀexico
b
Centro de Ciencias Aplicadas y Desarrollo Tecnolꢀogico (CCADET), Universidad Nacional Autꢀonoma de Mꢀexico, Cd. Universitaria,
Circuito Exterior, Coyoacꢀan, 04510 Mꢀexico City DF, Mꢀexico
c
ꢀ
ꢀ
ꢀ
Facultad de Quımica, 04510 Mexico City DF, Mexico
Received 11 March 2004; accepted 29 April 2004
Abstract
A series of palladium thiolate complexes of the type [Pd(dppf)(SRF)2] have been synthesized in good yields by metathetical
reactions of [Pd(dppf)Cl2] with [Pb(SRF)2], (SRF ¼ ꢀSC6F5, ꢀSC6F4-4-H, ꢀSC6H4-2-CF3, ꢀSC6H4-4-F, ꢀSC6H4-3-F) and their
crystal structures determined. The effect of the different thiolates in the structural properties of the complexes both in the solid state
and in solution have been analyzed. Heck coupling reactions were carried out using the complexes [Pd(dppf)(SRF)2], SRF ¼ ꢀSC6F5
(1), ꢀSC6F4-4-H (2), ꢀSC6H4-2-CF3 (3), ꢀSC6H4-4-F (4), ꢀSC6H4-3-F (5) as catalysts in order to examine both the effect of the
thiolates and the P–Pd–P bite angles in the reaction of bromobenzene and styrene. The results obtained indicate that electron-
withdrawing substituents may favor higher yields in the Pd catalyzed Heck reaction using [Pd(dppf)(SRF)2] as catalysts.
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Heck reaction; dppf; C–C coupling reactions; Fluorinated thiolate complexes; Palladium complexes; Crystal structures; Catalysis
1. Introduction
This is particularly true in the case of C–C coupling
reactions [4]. Thus, the high interest in these transfor-
mations has led different research groups to the design
and synthesis of alternative ferrocene based ligands,
including chiral inductors [5]. In addition, platinum
group metal complexes containing ferrocene and thio-
late ligands on its structure are rare [6], due in part to the
well known tendency of these complexes to polymerize
[7], affording in most of the cases intractable solids
useless as potential catalysts in homogeneous catalysis.
Moreover, compounds containing sulfur on its structure
have been left out from its possible applications as ho-
mogeneous catalysts due to the extended believe of
sulfur as a catalyst poison. Thus, given our continuous
interest in the design and synthesis of active and robust
complexes for employment as potential catalysts in
Since 1,10-bis(diphenylphosphino)ferrocene (dppf)
was first synthesized by Bishop et al. in 1971 [1], this
compound has been employed profusely for the syn-
thesis of complexes otherwise difficult or in some cases
almost impossible to isolate with other diphosphines
(e.g., dppe) [2]. In recent years, this capability of sta-
bilization, has been applied to the synthesis of species
with potential applications in homogeneous catalysis [3].
q Supplementary data associated with this article can be found, in the
online version, at doi:10.1016/j.jorganchem.2004.04.035.
* Corresponding author. Tel.: +52-555-622-4514; fax: +52-555-616-
2217.
E-mail address: damor@servidor.unam.mx (D. Morales-Morales).
0022-328X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.04.035

ꢀ
C. Herrera-Alvarez et al. / Journal of Organometallic Chemistry 689 (2004) 2464–2472
2465
industrial relevant transformations [8], we would like to
report here the use of dppf as a stabilizing ligand and
fluorinated thiolates as substituents for the fine tuning of
the electronics in the synthesis of a series of palla-
dium(II) complexes of the type [Pd(dppf)(SRF)2]. The
identification of the electronic effects of the different
fluorinated thiolates over the physical properties,
structure and reactivity in catalytic Heck reaction ex-
periments will be discussed.
ligand and a diphenylphosphine fragment from the
dppf ligand were also observed. Elemental analyses
for all the complexes are consistent with the proposed
formulations.
Crystals suitable for single crystal X-ray diffraction
analysis (Table 1) were obtained for all the complexes in
the series, once again these compounds share a number
of common structural features. The structures can be
defined as slightly distorted square planar in all cases,
having the palladium centers with the dppf ligand co-
ordinated in a bidentate manner and completing the
coordination sphere with the two thiolates adopting a
cis conformation, each trans to one phosphorus of the
dppf ligand. The main distortion is due to the steric
hindrance caused by the phenyl rings in the dppf ligand.
In all cases, the aromatic rings of the thiolates are not
eclipsed as has been observed in other cases due to p–p
interactions [10]. Instead, the aromatic rings are shifted,
in an anti configuration. It is probable that the fluoro-
benzene rings adopt this conformation due to steric
hindrance or to have optimal packing in the lattice.
The differences observed, particularly in the
31P{1H} NMR experiments, are complemented with
the results obtained from single crystal X-ray diffrac-
tion experiments. Here, the differences in changing the
thiolates are very clear. For instance, the Pd–S bond
lengths (Table 2) increase as the value of the Eg in-
creases in the following oꢀrder: ꢀSC6H4-4-F (2.34
2. Results and discussion
The reaction of one equivalent of the lead salt of the
corresponding thiolate [Pb(SRF)2] with one equivalent of
[Pd(dppf)(Cl)2] afford complexes 1–5 in good yields. All
compounds were obtained as analytically pure products
from recrystallization of CH2Cl2/MeOH solvent systems.
Given the similarity in the structures of these complexes,
common features in their spectroscopic properties exist.
The information obtained from 1H NMR of the series of
complexes is not very informative since only common
signals due to the presence of the aromatics and the cy-
clopentadienyl (Cp) rings in the dppf moiety are observed.
The 31P{1H} NMR spectra of the compounds are more
illustrative affording in all cases single resonances indic-
ative of magnetic equivalence of the P nuclei in the co-
ordinated dppf moiety. Another important feature in
these spectra is that the signals observed are sensitive, as
expected, to the number and position of fluorine atoms in
the aromatic ring. Thus, in the case of [Pd(dppf)(SC6F5)2]
(1) the signal is shifted to lower field (d ¼ 28.16 ppm) and
in the case of [Pd(dppf)(SC6H4-2-CF3)2] (3) the signal is
displaced to higher field (d ¼ 25:22 ppm); these two ex-
amples represent the upper and lower limits in the series of
complexes. This behavior can be rationalized from the
point of view of electron-withdrawing capability, being
higher in the case of complex 1 due the higher substitution
of fluorine of the aromatic ring, and therefore, with the
larger value of Group Electronegativity (Eg) [9], having as
the ultimate consequence the deshielding of the P nuclei in
the dppf moiety. Thus, the trend observed for the d
31P{1H} in the series of complexes [Pd(dppf)(SRF)2] is
ꢀSC6H4-2-CF3 (25.22 ppm) < ꢀSC6H4-3-F (25.55
ppm) < ꢀSC6H4-4-F (26.21 ppm) < ꢀSC6F4-4-H (27.65
ppm) < ꢀSC6F5 (28.16 ppm).
ꢀ
ꢁ
ꢁ
ꢁ
A) < SC6F4-4-H (2.35 A) < SC6F5 (2.36 A). This is
most likely the result of either steric hindrance or
electrostatic repulsion phenomena. Furthermore, it has
been noticed that depending on the position of the
fluorinated substituent on the aromatic ring, the Pd–S
bondꢀ lengths also vary -ꢀSC6H4-2-CF3 (2.37
ꢀ
ꢁ
ꢁ
ꢁ
A) > SC6H4-3-F (2.35 A) > SC6H4-4-F (2.34 A)-,
which may be a consequence of steric hindrance or a
result of the way the molecules pack in the lattice. An
analogous behavior is observed in the case of the Pd–
P bond distances, where a similar trend is observed,
(ꢀSC6H4-2-CF3
ꢀ
ꢁ
(2.314 A) < SC6F4-4-H (2.316
ꢀ
ꢁ
ꢁ
A) < SC6F5 (2.317 A)) however, in this case the trend
observed for the probable effect of the position of the
substituent in the aromatic ring is the opposite to the
case ꢀ exposed previously -ꢀSC6H4-2-CF3 (2.314
ꢀ
ꢁ
ꢁ
ꢁ
A) ¼ SC6H4-3-F (2.314 A) > SC6H4-4-F (2.319 A)-.
This fact, may indeed mean that the behavior ob-
served is mainly due to the packing in the lattice more
than a real influence due to steric hindrance. Another
clear trend can be observed in the values of the S–Pd–
S angles, where the smallest angle of the series is
observed for complex 1 which contains the thiolate
ligand ꢀSC6F5 with the higher value of Eg, while the
bigger angle corresponds to complex 4 which contains
the ligand ꢀSC6H4-4-F on its structure. A similar
trend is observed for the values of the P–Pd–P angles
where the smallest angle (98.41°) is once again
On the other hand, the 19F{1H} NMR experiments of
the synthesized complexes reveal the fluorinated thio-
lates to be present, with typical splitting patterns for the
ligands ꢀSC6F5 (1) and ꢀSC6F4-4-H (2) and singlets for
the cases ꢀSC6H4-2-CF3 (3), ꢀSC6H4-4-F (4), ꢀSC6H4-
3-F (5). These observed patterns are in agreement with
the proposed formulations. Additionally, analysis by
FABþ-Mass spectrometry shows in all cases the mo-
lecular ion of the fragment corresponding to the loss of
one thiolate ligand. Further loss of the other thiolate

ꢀ
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C. Herrera-Alvarez et al. / Journal of Organometallic Chemistry 689 (2004) 2464–2472
Table 1
Summary of crystal structure data for [Pd(dppf)(SRF)2] RF ¼ C6F5 (1), C6F4-4-H (2), C6H4-4-CF3 (3), C6H4-4-F (4), C6H4-3-F (5)
Compound
[Pd(dppf)
(SC6F5)2] (1)
[Pd(dppf)
(SC6F4-4-H)2] (2)
[Pd(dppf)
(SC6H4-2-CF3)2] (3)
[Pd(dppf)
(SC6H4-4-F)2] (4)
[Pd(dppf)
(SC6H4-3-F)2] (5)
Empirical formula
Formula weight
Temperature (K)
Crystal system
Space group
C46H28F10FeP2PdS2
1058.99
291(2)
C46H30F8FeP2PdS2
1023.01
291(2)
C48H36F6FeP2PdS2
934.06
291(2)
C46H36F2FeP2PdS2
915.06
291(2)
C46H36F2FeP2PdS2
915.06
291(2)
Monoclinic
P21=n
Monoclinic
P21=n
Monoclinic
C2=c
Monoclinic
P21=n
Monoclinic
P21=n
Cystal size (mm)
0.32 ꢁ 0.18 ꢁ 0.04
0.41 ꢁ 0.12 ꢁ 0.048
0.30 ꢁ 0.14 ꢁ 0.025
0.43 ꢁ 0.26 ꢁ 0.018
0.35 ꢁ 0.22 ꢁ 0.047
Unit cell dimensions
ꢁ
a (A)
11.1930(5)
20.7028(9)
18.5164(8)
90
10.881(1)
20.632(1)
18.532(1)
90
26.683(3)
11.5371(12)
15.0307(16)
90
19.219(1)
21.834(1)
19.939(1)
90
10.8854(14)
20.531(2)
18.341(2)
90
ꢁ
b (A)
ꢁ
c (A)
a (°)
b (°)
c (°)
Volume (A )
Z
94.75
90
94.52
90
115.59
90
108.08
90
95.79
90
3
ꢁ
4280.1(3)
4
1.643
4147.5(5)
4
1.638
4173.2(8)
4
1.487
7953.7(6)
4
1.543
4036.8(8)
4
1.506
Density (g/cm3)
h Range for data
collection
2.05 a 25°
1.97 a 25°
1.69 a 25°
1.42 a 25°
1.98 a 25°
Reflections collected
Independent
reflections
34 845
7528 ½Rint ¼ 0:087ꢂ
33 676
7311 ½Rint ¼ 0:07ꢂ
16 600
3677 ½Rint ¼ 0:11ꢂ
64 554
14 025 ½Rint ¼ 0:1]
7518
7115 ½Rint ¼ 0:04ꢂ
F ð000Þ
2112
None
2048
Analytic
1892
None
1856
Integration
3752
Analytic
Absorption
correction
Goodness-of-fit on F 2 0.770
0.984
1.000
1.020
0.984
R indices (all data)
R1 ¼ 0:079,
R1 ¼ 0:074,
wR2 ¼ 0:055
R1 ¼ 0:041,
wR2 ¼ 0:050
7311/0/541
R1 ¼ 0:053,
wR2 ¼ 0:105
R1 ¼ 0:046,
wR2 ¼ 0:102
3677/0/272
R1 ¼ 0:115,
wR2 ¼ 0:28
R1 ¼ 0:058,
wR2 ¼ 0:11
7115/0/488
R1 ¼ 0:111,
wR2 ¼ 0:070
R1 ¼ 0:052,
wR2 ¼ 0:061
14 025/2/988
wR2 ¼ 0:062
R1 ¼ 0:042,
wR2 ¼ 0:056
7528/0/55
Final R indices
½I > 2rðIÞꢂ
Data/restrains/
parameters
Index ranges
ꢀ13 6 k 6 13,
ꢀ24 6 h 6 24,
ꢀ22 6 l 6 22
1=2
ꢀ12 6 k 6 12,
ꢀ24 6 h 6 24,
ꢀ22 6 l 6 22
ꢀ31 6 k 6 31,
ꢀ13 6 h 6 13,
ꢀ17 6 l 6 17
0 6 k 6 12, 0 6 h 6 24, ꢀ22 6 k 6 22,
ꢀ21 6 l 6 21
ꢀ25 6 h 6 25,
ꢀ23 6 l 6 23
2
2 2
* S ¼ ½wðFoÞ ꢀ ðFcÞ Þ =ðn ꢀ pÞꢂ where n ¼ number of reflections and p ¼ total number of parameters.
2
2
2
2 1=2
** R1 ¼ jFo ꢀ Fcj=jFoj, wR2 ¼ ½wððFoÞ ꢀ ðFcÞ Þ =wðFoÞ ꢂ
.
observed for ꢀSC6F5 and the larger angle (102.2°) for
the compound containing the ligand ꢀSC6H4-2-CF3,
with the smallest Eg value (see Table 3).
of bromobenzene and styrene using N,N-dimethylfor-
mamide (DMF) as a solvent were carried out in the open
air at different reaction times, revealing that 2 h of re-
action time would yield enough product (stilbenes) to
observe a clear trend to be able to quantify the bite angle
effects as well as the effects due to the variation of the Eg
of the thiolates. Given the fact that single substituted
thiolates in different positions of the aromatic ring were
also employed, some insights with respect to the sterics
can also be obtained.
To better visualize the above-mentioned effects,
graphs of the yield of stilbenes versus P–Pd–P angle
(Graphic 1) and the yield of stilbenes versus Eg
(Graphic 2) were plotted. From this graphic, one ob-
serves that as the bite angle increases the yield of
stilbenes decreases, in accordance with the recent ob-
servations reported by Hayashi and co-workers [12].
However, in Graphic 1, one point lies out of this line.
In 1984, Hayashi first reported the use of the palla-
dium derivative [Pd(dppf)Cl2] as a superior catalyst in
C–C bond coupling reactions [11]. In fact, Gan and Hor
[3] have referred to this complex as a magic catalyst. The
outstanding reactivity was attributed to its larger P–Pd–
P bite angle (99.07°). However, recent studies by Hay-
ashi himself suggest that smaller P–Pd–P bond angles
might indeed be more important than larger bite angles
[12].
We believe that we have an ideal system to attempt to
shed some light in order to discriminate whether larger
or smaller P–Pd–P bite angles are important in palla-
dium catalyzed C–C bond forming reactions. Thus,
catalytic experiments were carried out employing the
complexes [Pd(dppf)(SRF)2] as catalysts. The reactions

ꢀ
C. Herrera-Alvarez et al. / Journal of Organometallic Chemistry 689 (2004) 2464–2472
2467
It may be possible that this particular complex may
not be as stable as the other analogous complexes
under the catalytic reaction conditions, which may
account for the lowering in yield.
In Graphic 2, yield of stilbenes versus Group
Electronegativity (Eg), an inverse behavior is observed,
(solid line), in which complex 1 (ꢀSC6F5 with the
highest value of Eg) displays the higher yield of the
reaction (21.45%). From this graphic, it is not clear
whether the position of the substituent in the aromatic
ring of the thiolate plays an important role in the
production of stilbenes. Thus, it seems that at least in
the present case, the electronics is a more important
factor than sterics, however this has to be investigated
further employing bigger substituents in the aromatic
ring of the thiolate. Moreover, from the graphs it
seems that a palladium system containing dppf as a
ligand and electron withdrawing substituents may
render complexes with smaller bite angles which in
turn may lead to an excellent catalyst for the high
yield catalyzed Heck reaction.
In summary, we have reported an efficient synthetic
monomeric
procedure
for
the
synthesis
of
[Pd(dppf)(SRF)2] complexes. These compounds have
been studied and clear trends can be observed for Eg
versus the properties of these species in solution and in
the solid state. Preliminary catalytic experiments indi-
cate that complexes containing small P–Pd–P bite angles
are more reactive than those with larger P–Pd–P angles.
A clear trend is also observed as the value of Eg is
varied, indicating that electron-withdrawing substitu-
ents may favor higher yields in the Pd catalyzed Heck
reaction using [Pd(dppf)(SRF)2] as the catalytic system.
Efforts aimed to employ these compounds in metal
mediated organic syntheses and other C–C coupling
reactions are currently under investigation.
3. Experimental
3.1. Materials and methods
Unless stated otherwise, all reactions were carried out
under an atmosphere of dinitrogen using conventional
Schlenk glassware and solvents were dried using estab-
lished procedures and distilled under dinitrogen imme-
diately prior to use. The IR spectra were recorded on a
Nicolet-Magna 750 FT-IR spectrometer as nujol mulls.
1
The H NMR (300 MHz) spectra were recorded on a
JEOL GX300 spectrometer. Chemical shifts are re-
ported in ppm down field of TMS using the solvent
(CDCl3, d ¼ 7:27) as an internal standard. 31P{1H}
NMR (121 MHz) and 19F{1H} spectra were recorded
with complete proton decoupling and are reported in
ppm using 85% H3PO4 and C6F6 as external standards,
respectively. Elemental analyses were determined on a

ꢀ
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C. Herrera-Alvarez et al. / Journal of Organometallic Chemistry 689 (2004) 2464–2472
Table 3
Heck couplings of bromobenzene with [Pd(dppf)(SRF)2] RF ¼ C6F5 (1), C6F4-4-H (2), C6H4-4-CF3 (3), C6H4-4-F (4), C6H4-3-F (5) as catalyst
P
SR
SR
F
F
Pd
Fe
P
Br
+
+
DMF
Base
E
Z
P–Pd bond lengthb (A)
Conversiona (%)
21.45
ꢁ
Entry
SRF
Eg
P–Pd–P angle (°C)
1
3.07
96.58(3)
2.3194(8)
F
F
S
F
F
F
F
2
2.92
98.46(4)
2.3124(11)
19.61
F
S
F
F
3
2.48
102.20(5)
2.3143(9)
11.42
F3C
S
4
5
2.48
2.48
97.88(5)
98.62(6)
2.3192(16)
2.3143(17)
13.75
17.60
F
S
F
S
Reaction conditions 50 mmol of halobenzene, 60 mmol of styrene, 60 mmol of base, 4.0 ꢁ 10ꢀ5 mmol of catalyst and 5 ml of DMF, 2 h at 120 °C.
a Yields obtained by GC are based on bromobenzene.
b Values are the average of the two different values observed for the Pd–P distances.
Perkin–Elmer 240. Positive-ion FAB mass spectra were
recorded on a JEOL JMS-SX102A mass spectrometer
operated at an accelerating voltage of 10 kv. Samples
were desorbed from a nitrobenzyl alcohol (NOBA)
matrix using 3 keV xenon atoms. Mass measurements in
FAB are performed at a resolution of 3000 using mag-
netic field scans and the matrix ions as the reference
material or, alternatively, by electric field scans with the
sample peak bracketed by two (polyethylene glycol or
cesium iodide) reference ions. GC–MS quantitative
analyses were performed on a Varian Saturn 3 with a
30.0 m DB-5 capillary column.
The 1,10-bis(diphenylphosphino)ferrocene (dppf) and
PdCl2 were obtained commercially from Aldrich Chem.
Co. Compounds [Pd(COD)Cl2] [13], [Pd(dppf)Cl2] [11]
and [Pb(SRF)2] [14]; RF ¼ C6F5, C6F4-4-H, C6H4-2-

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C. Herrera-Alvarez et al. / Journal of Organometallic Chemistry 689 (2004) 2464–2472
2469
P-Pd-P angle (o) vs Yield of stilbenes (%)
3.3. Synthesis of [Pd(dppf)(SC6F5)2] (1)
23
21
19
17
15
13
11
9
[Pd(dppf)(SC
F
)
]
6
5 2
To a solution of [Pd(dppf)(Cl)2] (50.0 mg, 0.068
mmol) in CH2Cl2 (10 ml), a solution of [Pb(SC6F5)2]
(41.3 mg, 0.068 mmol) in acetone (20 ml) was added
dropwise under stirring, the resulting red-brick solution
was allowed to stir overnight, after which time the so-
lution was filtered through a short plug of CeliteÒ and
the solvent removed under vacuum. The residue was
recrystallized from CH2Cl2–Hexane, to afford 1 as a
[Pd(dppf)(SC
F -4-H) ]
4 2
6
[Pd(dppf)(SC
H
-3-F) ]
4 2
6
[Pd(dppf)(SC
H -4-F) ]
4 2
6
[Pd(dppf)(SC
H
-2-CF ) ]
3 2
6
4
1
deep red microcrystalline powder. Yield 90%. NMR H
(300 MHz, CDCl3), d 7.95–7.25 (m, Ph, 20H), 4.43 (s,
Cp, 4H), 4.27 (s, Cp, 4H); NMR 31P{1H} (121 MHz,
CDCl3), d 28.16 (s, P); NMR 19F{1H} (282 MHz,
96
97
98
99
100
101
102
103
P-Pd-P angle (o)
Graphic 1.
3
CDCl3), d )135.08 (d, JFo–Fm ¼ 22:01 Hz, o-F),
3
)164.56 (t, JFm–Fp ¼ 22:01 Hz, p-F), )166.87 (m,
4JFo–Fp ¼ 4:79, m-F). Elementary Analalysis Calculated
for [C46H28F10Fe1P2Pd1S2] Calc. (%): C: 52.17, H: 2.66.
Found (%): C: 52.14, H: 2.68. MS-FABþ [Mþ] ¼ 1059
m=z.
CF3, C6H4-4-F, C6H4-3-F were synthesized according
to the published procedures.
3.2. General procedure for the synthesis of the complexes
[Pd(dppf)(SRF )2]
3.4. Synthesis of [Pd(dppf)(SC6F4-4-H)2] (2)
All the complexes were obtained using the same
experimental procedure. As a representative example
the synthesis of [Pd(dppf)(SC6F5)2] is described (see
Scheme 1).
[Pd(dppf)(Cl)2] (50.0 mg, 0.068 mmol) in CH2Cl2 (10
ml), a solution of [Pb(SC6F4-4-H)2] (39.0 mg, 0.068
mmol) in acetone (20 ml). Yield 83.5%. NMR H (300
1
Group electronegativity (Eg) vs Yield of stilbenes (%)
23
21
19
17
15
13
11
9
[Pd(dppf)(SC F ) ]
6
5 2
[Pd(dppf)(SC F -4-H) ]
6
4
2
[Pd(dppf)(SC H -3-F) ]
6
4
2
[Pd(dppf)(SC H -4-F) ]
6
4
2
[Pd(dppf)(SC H -2-CF ) ]
6
4
3 2
2.4
2.5
2.6
2.7
2.8
2.9
3
3.1
3.2
Group Electronegativity (Eg)
Graphic 2.
P
P
Cl
Cl
SRF
SRF
Pb(SRF)2
Fe
Pd
Pd
PbCl2
+
Fe
P
P
Scheme 1. Metathesis reactions for the synthesis of the complexes [Pd(dppf)(SRF)2].

ꢀ
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C. Herrera-Alvarez et al. / Journal of Organometallic Chemistry 689 (2004) 2464–2472
MHz, CDCl3), d 7.95–7.25 (m, Ph, 22H), 4.41 (s, Cp,
4H), 4.28 (s, Cp, 4H); NMR 31P{1H}(121 MHz,
CDCl3), d 27.65 (s, P); NMR 19F{1H} (282 MHz,
CDCl3), d )135.45 (m, 3JFo–Fm ¼ 24:27 Hz, o-F),
P
P
SRF
SRF
Pd
3
Fe
)143.75 (m, JFm–Fo ¼ 24:27 Hz, m-F). Elementary
Analysis Calculated for [C46H30F8Fe1P2Pd1S2] Calc. %:
C: 54.00, H: 2.96. Found %: C: 54.06, H: 2.98. MS-
FABþ [Mþ] ¼ 1022 m=z.
+
base
3.5. Synthesis of [Pd(dppf)(SC6H4-2-CF3)2] (3)
Br
[Pd(dppf)(Cl)2] (50.0 mg, 0.068 mmol) in CH2Cl2 (10
ml), a solution of [Pb(SC6H4-2-CF3)2] (38.4 mg, 0.068
1
mmol) in acetone (20 ml). Yield 76.5%. NMR H (300
Scheme 2. The palladium catalyzed Heck coupling reaction using
[Pd(dppf)(SRF)2] as the catalyst.
MHz, CDCl3), d 7.98–6.90 (m, Ph, 28H), 4.38 (s, Cp,
4H), 4.22 (s, Cp, 4H); NMR 31P{1H} (121 MHz,
CDCl3), d 25.23 (s, P); NMR 19F{1H} (282 MHz,
CDCl3), d )61.05 (s, CF3). Elementary Analysis Cal-
culated for [C48H36F6Fe1P2Pd1S2] Calc. %: C: 56.79, H:
3.57. Found %: C: 56.76, H: 3.58. MS-FABþ
[Mþ] ¼ 1014 m=z.
scribed reaction time (2 h), the mixture was cooled to
room temperature and the organic phase was analyzed
by gas chromatography (GC/FID, GC–MS). A Varian
Saturn 3 with DB-5 capillary column (30.0 m) was used
for quantitative GC analysis (see Scheme 2).
3.6. Synthesis of [Pd(dppf)(SC6H4-4-F)2] (4)
3.9. Data collection and refinement for [Pd(dppf)
(SC6F5)2] (1), [Pd(dppf)(SC6F4-4-H)2] (2), [Pd
(dppf)(SC6H4-2-CF3)2] (3), [Pd(dppf)(SC6H4-4-F)2]
(4), [Pd(dppf)(SC6H4-3-F)2] (5)
[Pd(dppf)(Cl)2] (50.0 mg, 0.068 mmol) in CH2Cl2 (10
ml), a solution of [Pb(SC6H4-4-F)2] (31.5 mg, 0.068
mmol) in acetone (20 ml). Yield 93.5%. NMR H (300
1
MHz, CDCl3), d 7.93–6.98 (m, Ph, 28H), 4.39 (s, Cp,
4H), 4.20 (s, Cp, 4H); NMR 31P{1H}(121 MHz,
CDCl3), d 26.21 (s, P); NMR 19F{1H} (282 MHz,
CDCl3), d )116.33 (s, p-F). Elementary Analaysis Cal-
culated for [C46H36F2Fe1P2Pd1S2] Calc. %: C: 60.37, H:
3.97. Found %: C: 60.34, H: 3.98. MS-FABþ [Mþ] ¼ 914
m=z.
Crystalline orange prisms for 1, 4 and 5 and red-or-
ange prisms for 2 and 3 were grown independently by
slow evaporation of CH2Cl2/MeOH solvent systems,
and mounted on glass fibers. In all cases, the X-ray in-
3.7. Synthesis of [Pd(dppf)(SC6H4-3-F)2] (5)
[Pd(dppf)(Cl)2] (50.0 mg, 0.068 mmol) in CH2Cl2 (10
ml), a solution of [Pb(SC6H4-3-F)2] (31.5 mg, 0.068
1
mmol) in acetone (20 ml). Yield 92.8%. NMR H (300
MHz, CDCl3), d 8.00–6.42 (m, Ph, 28H), 4.38 (s, Cp,
4H), 4.18 (s, Cp, 4H); NMR 31P{1H}(121 MHz,
CDCl3), d 25.55 (s, P); NMR 19F{1H}(282 MHz,
CDCl3), d )112.15 (s, m-F). Elementary Analysis Cal-
culated for [C46H36F2Fe1P2Pd1S2] Calc. %: C: 60.37, H:
3.97. Found %: C: 60.36, H: 3.94. MS-FABþ [Mþ] ¼ 914
m=z.
3.8. General procedure for the catalytic reactions
A DMF solution (5 ml) of 50.0 mmol of bromoben-
zene, 60.0 mmol of styrene, and the prescribed amount
of catalyst was introduced into a Schlenk tube in the
open air. The tube was charged with a magnetic stir bar
and an equimolar amount of base, sealed, and fully
immersed in a 120 °C silicon oil bath. After the pre-
Fig. 1. An ORTEP representation of the structure of
[Pd(dppf)(SC6F5)2] (1) at 50% probability showing the atom labeling
scheme.

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C. Herrera-Alvarez et al. / Journal of Organometallic Chemistry 689 (2004) 2464–2472
2471
tensity data were measured at 291 K on a Bruker
SMART APEX CCD-based X-ray diffractometer sys-
tem equipped with a Mo-target X-ray tube (k ¼ 0.71073
flections for 1, 2, 3, 4 and 5, respectively, to a maximum
ꢁ
2h angle of 50.00° (0.93 A resolution), of which 7528 (1),
7311 (2), 3677 (3), 14 025 (4) and 7115 (5) were inde-
pendent. Analysis of the data showed in all cases neg-
ligible decays during data collections. The structures
were solved by Patterson method using SHELXS-97 [16]
program. The remaining atoms were located via a few
cycles of least squares refinements and difference Fourier
maps, using the space group P21=n with Z ¼ 4 for 1, 2, 4
and 5 and C2/c with Z ¼ 4 for 3. Hydrogen atoms were
input at calculated positions, and allowed to ride on the
ꢁ
A). The detector was placed at a distance of 4.837 cm
from the crystals in all cases. A total of 1800 frames were
collected with a scan width of 0.3° in x and an exposure
time of 10 s/frame. The frames were integrated with the
Bruker SAINT software package [15] using a narrow-
frame integration algorithm. The integration of the data
was done using a monoclinic unit cell in all cases to yield
a total of 34 845, 33 676, 16 600, 64 554 and 7518 re-
Fig. 4. An ORTEP representation of the structure of [Pd(dppf)(SC6H4-
4-F)2] (4) at 50% probability showing the atom labeling scheme.
Fig. 2. An ORTEP representation of the structure of [Pd(dppf)(SC6F4-
4-H)2] (2) at 50% probability showing the atom labeling scheme.
Fig. 3. An ORTEP representation of the structure of [Pd(dppf)(SC6H4-
2-CF3)2] (3) at 50% probability showing the atom labeling scheme.
Fig. 5. An ORTEP representation of the structure of [Pd(dppf)(SC6H4-
3-F)2] (4) at 50% probability showing the atom labeling scheme.

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C. Herrera-Alvarez et al. / Journal of Organometallic Chemistry 689 (2004) 2464–2472
[5] T. Colacot, J. Chem. Rev. 103 (2003) 3101 (references therein).
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dron 20 (2001) 3189;
atoms to which they are attached. Thermal parameters
were refined for hydrogen atoms on the phenyl groups
ꢁ
using a Ueq ¼ 1:2 A to precedent atom in all cases. For
(b) O. Crespo, F. Canales, M.C. Gimeno, P.G. Jones, A. Laguna,
Organometallics 18 (1999) 3142;
all complexes, the final cycle of refinement was carried
out on all non-zero data using SHELXL-97 [16] and an-
isotropic thermal parameters for all non-hydrogen at-
oms. The details of the structure determinations are
(c) D-Y Noh, E-M Seo, H-J Lee, H-Y Jang, M-G Choi, Y.H.
Kim, J. Hong, Polyhedron 20 (2001) 1939;
(d) V.D. de Castro, G.M. de Lima, A.O. Porto, H.G.L. Siebald,
J.D. de Souza Filho, J.D. Ardisson, J.D. Ayala, G. Bombieri,
Polyhedron 23 (2004) 63;
ꢁ
given in Table 1 and selected bond lengths (A) and an-
gles (°) are given in Table 2, respectively. The numbering
of the atoms is shown in Figs. 1–5, respectively, (OR-
TEP) [17].
(e) T.F. Baumann, J.W. Sibert, M.M. Olmstead, A.G.M. Barrett,
B.M. Hoffman, J. Am. Chem. Soc. 116 (1994) 2639.
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[8] (a) D. Morales-Morales, R. Redon, Y. Zheng, J.R. Dilworth,
Inorg. Chim. Acta 328 (2002) 39;
(b) D. Morales-Morales, C. Grause, K. Kasaoka, R. Redon, R.E.
ꢀ
Cramer, C.M. Jensen, Inorg. Chim. Acta 300–302 (2000) 958;
ꢀ
(c) D. Morales-Morales, R. Redon, C. Yung, C.M. Jensen, Chem.
4. Supplementary material
Commun. 1619 (2000);
(d) D. Morales-Morales, R. Redon, Z. Wang, D.W. Lee, C. Yung,
Supplementary data for complexes 1, 2, 3, 4 and 5
have been deposited at the Cambridge Crystallographic
Data Centre. Copies of this information are available
free of charge on request from The Director, CCDC, 12
Union Road, Cambridge, CB2 1EZ, UK (fax: +44-1223-
336033; e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk) quoting the deposition numbers
CCDC 227072–227076.
ꢀ
K. Magnuson, C.M. Jensen, Can. J. Chem. 79 (2001)
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(e) D. Morales-Morales, R.E. Cramer, C.M. Jensen, J. Organo-
met. Chem. 654 (2002) 44;
(f) X. Gu, W. Chen, D. Morales-Morales, C.M. Jensen, J. Mol.
Catal. A 189 (2002) 119;
(g) J.R. Dilworth, P. Arnold, D. Morales, Y.L. Wong, Y. Zheng,
The chemistry and applications of complexes with sulphur ligands,
in: Modern Coordination Chemistry. The Legacy of Joseph Chatt,
Royal Society of Chemistry, Cambridge, UK, 2002, p. 217;
Acknowledgements
ꢀ
(h) D. Morales-Morales, S. Rodrıguez-Morales, J.R. Dilworth, A.
Sousa-Pedrares, Y. Zheng, Inorg. Chim. Acta 332 (2002) 101;
ꢀ
(i) V. Gomez-Benıtez, S. Hernandez-Ortega, D. Morales-Morales,
Inorg. Chim. Acta 346 (2003) 256.
ꢀ
ꢀ
C.H.-A and V.G.-B thank CONACYT for financial
support. We thank Chem. Eng. Luis Velasco Ibarra,
[9] D. Cruz-Garritz, J.A. Chamizo, M. Cruz, H. Torrens, Rev. Soc.
Quim. Mex. 33 (1989) 18.
ꢀ
M.Sc. Francisco Javier Perez Flores, QFB. Ma del
ꢀ
~
Rocıo Patino and Ma. de las Nieves Zavala for their
invaluable help in the running of the FABþ-Mass,
IR and 19F{1H} spectra, respectively. The support of
this research by CONACYT (J41206-Q) is gratefully
acknowledged.
[10] (a) L.S. Reddy, A. Nangia, V.M. Lynch, Crystallogr. Growth Des.
4 (2004) 89;
(b) D.B. Fox, R. Liantonio, P. Metrangolo, T. Pilati, G. Resnati,
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Hirotsu, J. Am. Chem. Soc. 106 (1984) 158.
[12] M. Ogasawara, K. Yoshida, T. Hayashi, Organometallics 19
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