Synthesis and characterization of Pd(II) complexes bearing NS, CS, SNS and SCS ligands. Evaluation of their microwave assisted catalytic activity in C–C coupling reactions

Article abstract of DOI:10.1016/j.poly.2020.114601

A series of coordination (Pd-NS, Pd-SNS, Pd-SNS-O) and organometallic (Pd-C and Pd-SCS) Pd(II) complexes supported by bidentate and tridentate ligands featuring sulphur moieties have been prepared. All ligands and their palladium complexes were fully char

Full text of DOI:10.1016/j.poly.2020.114601

Journal Pre-proofs
Synthesis and Characterization of Pd(II) Complexes Bearing NS, CS, SNS
and SCS Ligands. Evaluation of Their Microwave Assisted Catalytic Activity
in C-C Coupling Reactions
G. Gabriel Flores-Rojas, Lucero González-Sebastián, Reyna Reyes-Martínez,
Bethsy A. Aguilar-Castillo, Simón Hernández-Ortega, David Morales-
Morales
PII:
S0277-5387(20)30258-8
DOI:
Reference:
https://doi.org/10.1016/j.poly.2020.114601
POLY 114601
To appear in:
Polyhedron
Received Date:
Revised Date:
Accepted Date:
17 January 2020
4 May 2020
6 May 2020
Please cite this article as: G. Gabriel Flores-Rojas, L. González-Sebastián, R. Reyes-Martínez, B.A. Aguilar-
Castillo, S. Hernández-Ortega, D. Morales-Morales, Synthesis and Characterization of Pd(II) Complexes Bearing
NS, CS, SNS and SCS Ligands. Evaluation of Their Microwave Assisted Catalytic Activity in C-C Coupling
Reactions, Polyhedron (2020), doi: https://doi.org/10.1016/j.poly.2020.114601
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Synthesis and Characterization of Pd(II) Complexes Bearing NS, CS,
SNS and SCS Ligands.
Evaluation of Their Microwave Assisted Catalytic Activity in C-C
Coupling Reactions
G. Gabriel Flores-Rojasa, Lucero González-Sebastiána, Reyna Reyes-Martínezb, Bethsy
A. Aguilar-Castilloa, Simón Hernández-Ortegaa and David Morales-Moralesa,*
aInstituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior
s/n, Ciudad Universitaria, C.P. 04510, México, CDMX. bFacultad de Ciencias
Químicas, Universidad Autónoma de Chihuahua. Circuito Universitario S/N.
Chihuahua, Chihuahua, C. P. 31125. México.
*Corresponding author. Tel.: +52 55 56224514; fax: +52 55 56162217.
E-mail address: damor@unam.mx (D. Morales-Morales)
Abstract
A series of coordination (Pd-NS, Pd-SNS, Pd-SNS-O) and organometallic (Pd-C and
Pd-SCS) Pd(II) complexes supported by bidentate and tridentate ligands featuring
sulphur moieties have been prepared. All ligands and their palladium complexes were
fully characterized by various analytical techniques, including the unequivocal
determination of the solid-state structures of the ligand L-SNS-O and the Pd-CS and
Pd-NS complexes by single crystal X-ray diffraction analysis. Complexes Pd-NS, Pd-
SNS, Pd-CS, Pd-SCS containing thioether groups were used as efficient catalysts in
microwave-assisted Suzuki-Miyaura and Mizoroki-Heck C-C cross-coupling reactions,
showing the organometallic catalysts (Pd-CS, Pd-SCS) to produce the better
conversions, most likely due to enhanced thermal stability provided by the Pd-C bonds.
Keywords: C-C cross-coupling; Heck-Mizoroki reaction; Suzuki-Miyaura Reaction,
Palladium complexes; Pincer Complexes, Catalysis.

1. Introduction
The applications of palladium complexes pervade in modern synthetic chemistry and
have become ubiquitous in organometallic chemistry and catalysis. In part, because
these complexes are among the most efficient catalysts for cross-coupling reactions
leading to the formation of new C-C bonds allowing the design of new organic
compounds with a wide range of different uses, such as new materials, optical devices,
pharmaceuticals, and sensors. [1-4] The Suzuki-Miyaura and the Mizoroki-Heck
reactions are among the best studied Pd-catalyzed coupling reactions. Currently, the
Suzuki-Miyaura couplings between organic halides and boronic acids is one of the most
versatile synthetic and successful methods for the construction of biaryls and substituted
aromatic moieties. [5-7] Additionally, the Mizoroki-Heck reaction is also a very
attractive process enabling the coupling of organic halides with alkenes to produce
substituted alkenes with high stereoselectivity for trans coupling. [8-11]
In this regard, palladium compounds bearing electron-rich phosphines have
proved to be excellent catalysts precursors for these types of transformations. [12-14]
However, the preparation of palladium complexes containing phosphines derivatives is
often hampered by rigorous synthetic methods required to produce these ligands.
Therefore, the research interest is now expanding to use novel phosphine-free, air- and
water-stable and easy to synthesize catalysts. [15-20] The applications of these systems
combined with the use of alternative energy sources such as microwave irradiation
(MW), may lead to more eco-friendly, economical and sustainable protocols, themes of
great relevance nowadays. The use of microwave irradiation has undeniable advantages
compared with the conventional heating as superb reduction of reaction times, faster
reaction kinetics and cleaner products. [21-23] Thus, following our continuous interest
in the chemistry of sulphur donor ligands, [20,23] we report on this opportunity a series
2

of Pd(II) complexes bearing naphthalene substituted thioether ligands (Pd-NS, Pd-SNS,
Pd-CS, Pd-SCS) and their use as catalysts in Suzuki-Miyaura and Mizoroki-Heck
couplings under microwave irradiation.
2. Results and discussion
2.1 Synthesis and characterization of the ligands L-CS, L-NS, L-SCS, L-SNS
The ligands were prepared in excellent yields via a nucleophilic attack of the
naphthalene-2-thiolate over (bromomethyl)benzene, 2-(bromomethyl)pyridine, 1,3-
bis(bromomethyl)benzene, 2,6-bis(bromomethyl)pyridine and pyridine-2,6-dicarbonyl
dichloride in the presence of a base to give the corresponding compounds (Scheme 1).
Scheme 1. Synthesis of ligands L-CS, L-SN, L-SCS, L-SNS, L-SNS-O.
3

The structure of the ligands, L-CS, [24,25] L-SN, [26] L-SCS, [27] was
confirmed by direct comparison of multinuclear NMR (1H, 13C{1H}), mass
spectrometry and melting point data previously reported on the literature. The new
ligands L-SNS and L-SNS-O were also fully characterized by the common analytical
techniques quoted above. All the ligands display protonated molecular ion peaks in their
electron impact mass spectra and signals for the thiomethylene protons (CH2-S) in the
1
range of  4.07-4.37 ppm in their H NMR spectra, except for the ligand L-SNS-O,
which does not contain the thiomethyl group. The elemental analyses of the ligands L-
SNS and L-SNS-O agree well with the proposed formulations. Further confirmation of
the composition of L-SNS-O was achieved by single crystal X-ray determination.
2.1.1 Crystal structures of L-SNS-O
The molecular structure of L-SNS-O with the atom labelling is shown in Figure
1, crystallographic data and details of structure determination are given in Table 1. The
compound L-SNS-O crystallized in an orthorhombic system Cmc21. The asymmetric
unit contains half of the molecule and the other half is generated by application of a
mirror plane.
Figure 1. Molecular structure of L-SNS-O. Thermal ellipsoids are drawn at 50% of
probability level.
4

L-SCS-O presents a pyridine ring with two thioester groups in the 2 and 6
positions. The bond distances in C=O and C-S are 1.202(2) and 1.778(2) Å respectively,
which are comparable with values reported for these types of bonds. Both pyridyl and
thioester groups are found in the same plane. The planes of the pyridyl and naphthalene
moieties are perpendicular with an angle of 69.92o. The crystal packing is dominated by
the C-H--O=C hydrogen bonds and the C6C6--O1=C5 (d = 2.52 Å) and C12-H12--π
(dCg-H= 2.98 Å) interactions generating a chain motif along the c axis (Figure 2). Those
interactions that are extended along the c axis along with other C-H--- π interactions
(Table 2) give place to the supramolecular array.
Figure 2. 1-D chain structure of ligand L-SNS-O formed by C-H---O=C, and C6-H---
O=C interactions. Hydrogen atoms that do not participate in the interactions are omitted
for clarity.
5

Table 1. Structural data and refinement for ligands L-SCS and L-SNS-O and palladium
complexes Pd-CS and Pd-NS.
L-SNS-O
Pd-CS
Pd-NS
Formula
C27H17NO2S2
C34H26Cl2Pd2S2
2(CHCl3)
1021.10
Monoclinic
P21/c
12.0476(5)
17.8986(7)
9.4460(4)
90
C16H13Cl2NPdS
Formula weigh
Crystal system
Space group
a (Å)
b (Å)
c (Å)
451.54
Orthorhombic
Cmc21
37.4321(15)
7.8319(3)
7.6128(3)
90
428.63
Monoclinic
C2/c
26.1557(10)
8.5932(3)
15.1931(6)
90
 (°)
90
107.124(1)
90
98.493(1)
90
 (°)
 (°)
V (Å3)
90
2231.80(15)
4
1946.59(14)
2
3377.4(2)
8
Z
 calc (g/cm3)
1.344
1.742
1.686
T (K)
298
298
298
R(%)
4.09
2.46
Table 2. Hydrogen bonding lengths in the crystal structures.
D-H∙∙∙A
D-H (Å)
H∙∙∙A (Å)
D∙∙∙A (Å)
Symmetry code
DHA
(°)
L-SNS-O
C6-H6∙∙∙O1
C8-H8∙∙∙Cg1 0.93
C12-
0.93
2.52
2.87
2.98
3.352(2)
3.538(2)
3.705(2)
149
130
136
x, 1-y, ½+z
x, 2-y, -1/2+z
x, 1-y, ½+z
0.93
H12∙∙∙Cg2
C9-H9∙∙∙Cg2 0.93
Pd-CS
2.83
2.84
3.652(2)
3.474(5)
147
124
x, 2-y, -1/2+z
x, ½-y, -1/2+z
C7-
0.97
H7A∙∙∙Cg1
Pd-NS
C5-H5∙∙∙Cl1 0.93
2.83
2.71
3.663(3)
3.622(3)
150
156
x, 1+x, z
x, -y, ½+z
C7-
0.97
H7A∙∙∙Cl1
C7-H7B∙∙∙Cl2 0.97
2.78
3.590(3)
142
2-x, -y, -z
L-SNS-O: Cg1: C6,C7,C9,C15,C14; C10,C11,C12,C13,C14,C15. Pd-CS: Cg1:C1-C6.
2.2 Synthesis and characterization of the Pd(II) complexes
Palladium complexes were synthesized via two different routes. First, the direct
cyclopalladation of the ligands L-CS and L-SCS at the C2 position of the central phenyl
6

ring was achieved by refluxing equimolar amounts of L-CS or L-SCS and
[PdCl2(MeCN)2] in the presence of a base in acetonitrile for 24 h to afford the
corresponding palladium complexes Pd-CS and Pd-SCS in good yields. Compound Pd-
CS was obtained as a dimeric species. On the other hand, the coordination compounds
Pd-NS, Pd-SNS and Pd-SNS-O were synthesized in excellent yields by reacting the
ligands, L-NS, L-SNS and L-SNS-O, with [PdCl2(MeCN)2] in dichloromethane at room
temperature for 2 h (Scheme 2).
Scheme 2. Synthesis of palladium complexes Pd-CS, Pd-SN, Pd-SCS, Pd-SNS, Pd-SNS-O.
7

The formation of palladium complexes was fully confirmed using a combination
of analytical techniques such as, NMR spectroscopy, mass spectrometry and elemental
1
analysis. For instance, by comparing the H NMR spectra of the ligands L-CS and L-
SCS with those of the complexes Pd-CS and Pd-SCS, it is possible to observe that one
of the resonances of the aromatic protons (7.8-7.1 ppm) is absent in the latter, indicating
the C-palladation of the phenyl ring has occurred. Additionally, the 1H NMR spectra of
all palladium complexes, except Pd-SCS-O, show downfield shifted signals assigned to
the thiomethylene (CH2-S) protons due to the coordination of the ligand to the Pd
1
center. Notably, the H NMR spectrum of Pd-CS displays two broad singlets at 4.19
and 4.51 ppm attributed to the diastereotopic protons (-CH2S), in contrast with the
1
singlet observed in the free ligand (4.15 ppm), while the H NMR spectra of the
complexes Pd-NS, Pd-SCS, Pd-SNS exhibit broad singlets assigned to -CH2S at 4.73,
4.63 and 5.44 ppm respectively ( in ppm for -CH2S in the free ligands: L-NS: 4.37, L-
SCS: 4.07 and L-SNS: 4.33). Additionally, the structure of Pd-CS and Pd-NS was fully
authenticated by single-crystal X-ray diffraction analysis.
2.2.1 Crystal structures of Pd-SC and Pd-SN
A perspective view of complex Pd-CS is given in Figure 3. Crystal and data
collection details for the palladium complex Pd-CS are shown in Table 1. The crystal
structure of Pd-CS belongs to the monoclinic system (P21/c). The asymmetric unit
contains half of the molecule along with a chloroform molecule. The centrosymmetric
structure of Pd-CS comprises two palladium centers in a distorted square planar
geometry bridged through the chlorine atoms. Each palladium atom is coordinated to
two bridging chlorides [dCl-Pd= 2.3625(13) and 2.4615(14) Å] as well as to the C [dC-Pd
=
1.985(5) Å] and S [dS-Pd= 2.2404(13) Å] atoms of the ligand L-CS generating
8

palladacycles of five members. The supramolecular array is dominated by weak C-H--
interactions and van der Waals forces. The C7-H7A∙∙∙π (dCg-H= 2.84 Å) interactions give
place to a two-dimensional arrangement parallel to the bc plane illustrated in Figure 4.
The solvent molecules are stabilized by free electron pair- (C-Cl--) interactions with
distances of (3.639(3) Å for C16-Cl2∙∙∙Cg1(C1-C6) and 3.591(3) Å for C16-
Cl4∙∙∙Cg2(C11a,C12-C15,C15A)). These values are quite similar to other reported Cl--
interactions.
Figure 3. Molecular structure of complex Pd-CS. Thermal ellipsoids are drawn at 50%
probability level. Selected bond lengths (Å): Pd(1)-C(1) 1.985(5); Pd(1)-S(1)
2.2404(13); Pd(1)-Cl(1) 2.3624(13); Pd(1)-Cl(1)#1 2.4616(13); Cl(1)-Pd(1)#1
2.4616(13). Selected bond angles (°): C(1)-Pd(1)-S(1) 84.52(14); C(1)-Pd(1)-Cl(1)
96.51(14); S(1)-Pd(1)-Cl(1) 176.06(5); C(1)-Pd(1)-Cl(1)#1 177.21(14); S(1)-Pd(1)-
Cl(1)#1 92.72(5); Cl(1)-Pd(1)-Cl(1)#1 86.23(5); Pd(1)-Cl(1)-Pd(1)#1 93.78(5)
9

Figure 4. Fragment of the arrangement generated by C-H--π interactions in complex
Pd-CS. Hydrogen atoms not participating in the interactions are omitted for clarity.
The complex Pd-NS crystalized in a monoclinic system (C2/c) with one
molecule of complex by asymmetric unit. Details of crystal data and refinements are
shown in the table 1. Complex Pd-NS is a mononuclear species in which the Pd(II)
atom is tetracoordinated to two chloride atoms (dCl-Pd= 2.2913(7) and 2.3134(8) Å) and
to the bidentate L-NS ligand through the nitrogen (dN-Pd= 2.0447(19) Å) and sulphur
(dS-Pd= 2.2621(8) Å) atoms forming a five-membered ring. The Pd-NS complex adopts
a distorted square-planar geometry around the palladium center (Figure 5). Also, the
structure is disordered in the naphthalene group generating two orientations in
approximately 52:48 ratio. Only the major contributor is shown in Figure 5. The
presence of highly polar bonds given by the chloride ions and the Pd allows the
formation of intermolecular C-H--Cl-Pd hydrogen bonds, which are an important
feature in the solid-state packing. Thus, the interactions C5-H5—Cl1 (dH-Cl= 2.83 Å)
10

and C7-H7A—Cl1 (dH-Cl= 2.71 Å) generate a two-dimensional arrangement parallel to
the bc plane as shown in Figure 6. In addition, the Cl2 atom forms an interaction with
the hydrogen of the methylene group (H7B) (dCl2-H&B= 2.78 Å) giving a dimeric species
(Figure 7).
Figure 5. Molecular structure of complex Pd-NS. Thermal ellipsoids are drawn at 40%
probability level. The disorder in the naphthalene group is omitted for clarity. Selected
bond lengths (Å): Pd(1)-N(1) 2.045(2); Pd(1)-S(1) 2.2621(7); Pd(1)-Cl(1) 2.2913(7);
Pd(1)-Cl(2) 2.3134(7). Selected bond angles (°): N(1)-Pd(1)-S(1) 85.22(6); N(1)-Pd(1)-
Cl(1) 174.39(6); S(1)-Pd(1)-Cl(1) 89.34(3); N(1)-Pd(1)-Cl(2) 94.20(6); S(1)-Pd(1)-
Cl(2) 178.58(3); Cl(1)-Pd(1)-Cl(2) 91.27(3).
Figure 6. Fragment of the arrangement generated by C-H--Cl interactions in complex
Pd-NS. Hydrogen atoms not participating in the interactions are omitted for clarity.
11

Figure 7. Dimeric arrangements of complex Pd-NS generated by the C-H7B--Cl2
interaction.
3. Catalytic activity
3.1 Suzuki-Miyaura cross-couplings
With the palladium complexes in hand, their activity was evaluated in Suzuki-
Miyaura cross-couplings under the optimized reaction conditions previously established
in our laboratory using analogous catalytic systems.[20] Initially, all palladium
complexes were screened in the coupling reaction of bromobenzene with phenylboronic
acid (selected as a model reaction), and the results are summarized in Table 3. Among
all screened complexes, Pd-CS was by far the most efficient catalyst affording the
coupled product 3 in 39 % (Table 3, entry 1). In general, palladacycle compounds Pd-
CS and Pd-SCS showed better results than coordination compounds Pd-NS and Pd-
SNS (Table 3, entries 1 and 3). While the Pd-SNS-O complex was not active in this
coupling reaction under these conditions (Table 3, entry 5) probably due to
decomposition, which was evidenced by the formation of palladium black. The Pd-
SNS-O decomposition may be associated to a higher hemilabile character in the S-Pd
coordination bond related to a decrease of the  donor character of the S by the thiolate
groups compared with the S-Pd coordination bond in the compounds bearing thioether
groups.
12

Table 3. Suzuki-Miyaura couplings catalyzed by Pd-CS, Pd-SN, Pd-SCS, Pd-SNS, Pd-SNS-O.
Entry
Pd-cat.
Pd-CS
Pd (mol %)
Yield of 3 (%)
1
2
3
4
5
1
1
1
1
1
39.2
8.6
Pd-NS
Pd-SCS
Pd-SNS
Pd-SNS-O
22.8
6.4
ND
Reaction conditions: [Pd] (0.01 mmol), bromobenzene (1 mmol), PhB(OH)2 (1.2
mmol), Na2CO3 (2.4 mmol), DMF/H20 4:1 (5 mL), 100 W, 10 min. Yields were
determined by GC-MS analysis and are the average of two runs. ND: Not detected
As is well known, the Suzuki-Miyaura couplings are strongly dependent on the
base used, thus, several bases were tested under the optimized reaction conditions using
the best-found catalyst, Pd-CS (Table 4). The results obtained revealed that the
inorganic bases are the most efficient and, as expected from our previous reports, the
best yield was obtained when Na2CO3 was employed giving a conversion of 38.9 %.
Organic bases such as Et3N and DMAP were found not effective (Table 4, entries 7 and
8).
Table 4. Suzuki-Miyaura couplings catalyzed by Pd-CS using different bases.
Entry
Base
Yield of 3 (%)
1
2
3
4
K2CO3
Na2CO3
Na3PO4
Li2CO3
16.1
38.9
10.3
9.7
13

5
7
8
Cs2CO3
Et3N
29.2
ND
ND
DMAP
Reaction conditions: [Pd] (0.01 mmol), bromobenzene (1 mmol), PhB(OH)2 (1.2
mmol), base (2.4 mmol), DMF/H20 4:1 (5 mL), 100 W, 10 min. Yields were determined
by GC-MS analysis and are the average of two runs. ND: Not detected
3.1.1 Scope of the Pd-CS-catalyzed Suzuki-Miyaura cross-coupling reactions.
In order to examine the scope and limitations of the catalytic system, the
optimized reaction conditions were applied to the coupling of phenylboronic acid with a
series of substituted aryl bromides (Table 5). The results show a clear correlation
between the yield of product and the nature of the aromatic substituent para to Br or its
Hammett substituent constant. [28] Thus, excellent conversions were observed with
electron-withdrawing (EWG) substituents with TONs up to 600 h-1 (Table 5, entries 5-
8) and low conversions with electron-donating groups (EDG) (Table 5, entry 3). When
4-bromoaniline or 4-bromophenol were used no conversion was detected. This probably
being due to coordination of this substrates to the metal center, hence hindering its
function as catalyst.
Table 5. Suzuki-Miyaura couplings of PhB(OH)2 and different para substituted
bromobenzenes using Pd-CS as catalyst.
Entry
-X (1)
-NH2
-OH
-CH3
-H
Yield of 3 (%)
TOF/h-1
---
1
2
3
4
ND
ND
---
15.9
39.2
95
227
14

5
6
7
8
-CHO
-COCH3
-CN
≥99
≥99
≥99
≥99
≥600
≥600
≥600
≥600
-NO2
Reaction conditions: [Pd] (0.01 mmol), para substituted aryl bromide (1 mmol),
PhB(OH)2 (1.2 mmol), Na2CO3 (2.4 mmol), DMF/H20 4:1 (5 mL), 100 W, 10 min.
Yields were determined by GC-MS analysis and are the average of two runs. ND: Not
detected.
It is well known that some palladium complexes often decompose to Pd(0)
nanoparticles during coupling reactions, and even a trace of such species can catalyze
the reaction, thus palladium complexes merely serve as precatalyst. Hence, in order to
investigate the probable involvement of Pd(0) nanoparticles during the Suzuki-Miyaura
couplings catalyzed by Pd-CS, the standard catalytic reaction was carried out adding
drops of elemental mercury (Hg) wherein the yield of coupling product 3 obtained was
unaltered (38.9 %) (Scheme 3). The presence of mercury did not suppress the C-C
coupling suggesting that molecular palladium is responsible of the observed activity.
Scheme 3. Suzuki-Miyaura coupling between bromobenzene and phenylboronic acid
Pd-CS-catalyzed under the optimized reaction conditions in the presence of elemental
mercury.
3.2 Mizoroki-Heck cross-couplings
The synthesized palladium complexes were also examined as catalysts in the
Mizoroki-Heck cross-coupling reaction using microwave irradiation. Thus, the catalytic
activity of palladacycles (Pd-CS and Pd-SCS) and coordination compounds (Pd-NS and
Pd-SNS, Pd-SNS-O) was examined in a model reaction between bromobenzene and
15

styrene (Table 6). As previously observed the palladacycles (entries 1 and 3) exhibited a
better activity compared to the coordination compound Pd-NS (entry 2) with the usual,
trans-selectivity of the Mizoroki-Heck couplings, observing only less of 1 % of the cis
product. In this case, the complex Pd-SNS-O also decomposed before any coupled
product could be formed and thus were not detected (Entry 5).
Table 6. Mizoroki-Heck couplings catalyzed by Pd-CS, Pd-SN, Pd-SCS, Pd-SNS, Pd-SNS-O.
Entry
Pd-cat.
Pd-CS
Pd (mol %)
Yield of 3A (%)
1
2
3
4
5
1
1
1
1
1
28.5
22.2
26.8
9.6
Pd-NS
Pd-SCS
Pd-SNS
Pd-SNS-O
ND
Reaction conditions: [Pd] (0.01 mmol), bromobenzene (1 mmol), styrene (1.2 mmol),
Na2CO3 (2.4 mmol), DMF/H20 4:1 (5 mL), 100 W, 10 min. Yields were determined by
GC-MS analysis and are the average of two runs. ND: Not detected
The palladacycle Pd-CS proved again to be the best catalyst in the Mizoroki-
Heck couplings. Thus, it was used to test the effect of the base in this reaction (Table 7).
The use of Na2CO3 gave the highest conversion, and as it was the case for the Suzuki-
Miyaura couplings, organic bases were not efficient in this process.
Table 7. Mizoroki-Heck couplings catalyzed by Pd-CS using different bases.
16

Entry
Base
K2CO3
Na2CO3
Na3PO4
Li2CO3
Cs2CO3
Et3N
Yield of 3a (%)
1
2
3
4
5
7
8
7.8
28.5
9.7
2.6
7.2
ND
ND
DMAP
Reaction conditions: [Pd] (0.01 mmol), bromobenzene (1 mmol), styrene (1.2 mmol),
base (2.4 mmol), DMF/H20 4:1 (5 mL), 100 W, 10 min. Yields were determined by GC-
MS analysis and are the average of two runs. ND: Not detected
3.2.1 Scope of the Pd-CS-catalyzed Mizoroki-Heck couplings
Under the optimized conditions, the catalytic activity of Pd-CS was assessed in
Mizoroki-Heck couplings using styrene and different para substituted aryl bromides. As
noticed in the Suzuki-Miyaura couplings, the catalytic activity depends on the
bromobenzene substituents. In this regard, the results presented in Table 8 exhibit a
direct correlation between the yield to products and the nature of the aromatic
substituent para to Br, or its Hammett substituent parameter.[28] The conversions in the
Mizoroki-Heck couplings were moderate with electron-withdrawing groups (entries 5-
8) and lower conversions were obtained with aryl bromides having electron-donating
groups (entries 3 and 4) with a remarkable trans-selectivity (1% of cis-product was
observed in all the cases). On the other hand, the bromobenzenes including para -NH2
or OH groups were inactive under these reaction conditions (entries 1 and 2) once again
very likely due to coordination to the Pd center. These results suggest that the rate-
determining step for both Suzuki-Miyaura and Mizoroki-Heck couplings is the
oxidative addition of the aryl bromide to the metal center, which could be facilitated
with electron-withdrawing groups on the aromatic ring.
17

Table 8. Mizoroki-Heck couplings of styrene and different para substituted aryl
bromides catalyzed by Pd-CS.
Entry
-X (1)
-NH2
-OH
Yield of 3a (%)
TOF/h-1
---
1
2
3
4
5
6
7
8
ND
ND
---
-CH3
-H
3.3
20
28.5
62.5
55.1
61.8
63.8
155
375
331
371
383
-CHO
COCH3
-CN
-NO2
Reaction conditions: [Pd] (0.01 mmol), para substituted aryl bromide (1 mmol), styrene
(1.2 mmol), Na2CO3 (2.4 mmol), DMF/H20 4:1 (5 mL), 100 W, 10 min. Yields were
determined by GC-MS analysis and are the average of two runs. ND: Not detected
Finally, with exception of complex Pd-SNS-O, in all systems investigated in the
Mizoroki-Heck couplings, no decomposition of the complexes or formation of metallic
palladium was observed. And, as it was the case in the Suzuki-Miyaura couplings the
catalytic performance of Pd-CS was not affected by the presence of elemental mercury.
4. Conclusions
With the aim to provide air-, water-, and thermally stable catalytic systems a
series of coordination (Pd-NS, Pd-SNS, Pd-SNS-O) and organometallic (Pd-CS, Pd-
SCS) Pd(II) complexes bearing thioether and thiolato groups were successfully
synthesized in high yields and fully characterized. These reactions can be performed in
air, rendering these systems highly attractive for synthetic purposes. With the
18

complexes on hand, their microwave assisted catalytic activity was examined in Suzuki-
Miyaura and Mizoroki-Heck cross-coupling reactions. Apart from complex Pd-SNS-O
that decomposed under these reaction conditions, all other complexes catalyze these
reactions leading to moderate to excellent conversions with TONs up to 600 h-1 and 383
h-1 for Suzuki-Miyaura and Mizoroki-Heck couplings, respectively. Remarkably, in
both cases the use of microwave irradiation notably reduced reaction times for the C-C
couplings showing a clear advantage over the conventional heating.
5. Experimental section
Unless otherwise noted, all experiments were carried out in atmospheric
conditions. Solvents were purchased from Aldrich and dried under standard procedures.
THF was dried and distilled from dark-purple solutions of sodium/ benzophenone ketyl
radical. CH2Cl2 was dried over CaH2. All other chemicals and filter aids were reagent
grade and were used as received. Compound [PdCl2(MeCN)2] (1) were prepared
according to the reported procedure. [29] Column chromatography was performed on
silica gel (Merck, 230-700 mesh). Melting points were determined on a MEL-TEMP II
in an open capillary tube. Elemental analyses were performed in a Thermo Scientific
Flash 2000 elemental analyzer. The X-ray crystallographic analyses were made on a
1
13
Bruker P4 diffractometer. The H, and C{1H} Nuclear Magnetic Resonance (NMR)
was performed on a JEOL 300 MHz equipment, using TMS or residual protio solvents
as internal standard. The deuterated solvent used was CDCl3; chemical shifts (d) are
quoted in ppm and coupling constants in Hz.; to indicate the multiplicity of the signals
of 1H NMR spectra, the following abbreviations have been used: (s) singlet, (d) doublet,
(t) triplet, (m) multiplet, (dd) double doublet. Catalysis experiments were performed in a
CEM Discover reactor connected to a CEM Explorer robotic system. Catalysis products
19

were quantified with a GC-MS Agilent 6890N chromatograph equipped with a 30 m
DB-1MS Agilent capillary column, coupled to an Agilent Technologies 5973 Mass
Spectrometer equipped with an Inert Mass Selective Detector. Mass spectrometry of
pure compounds were performed on a Thermo-Electron DFS (EI-MS), on a JEOL JMS
AX505HA (FAB-MS) Mass measurements in FAB+ were performed at a resolution of
3000 using magnetic 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. MS-Electrospray determinations
were recorded on a Bruker Daltonics-Esquire 3000 plus Electrospray Mass
Spectrometer.
5.1. Preparation of ligands (L-CS, L-SN, L-SCS, L-SNS, L-SNS-O)
5.1.1. General procedure:
Ligands were prepared by slight modifications of procedures described in the
literature. [20, 23, 30]. A solution of naphthalene-2-thiol (RSH) (ca. 1 mmol) and NaH
(1.1 equivalents) in 15 mL of dry THF was stirred for 5 min at room temperature. Then,
1 equivalent of (bromomethyl)benzene (L-CS), 2-(bromomethyl)pyridine (L-SN) or 0.5
equivalent 1,3-bis(bromomethyl)benzene (L-SCS), 2,6-bis(bromomethyl)pyridine (L-
SNS), pyridine-2,6-dicarbonyl dichloride (L-SNS-O) derivatives was added. The
reaction mixture was stirred at room temperature for 24 h. After this time, 10 mL of
water were added to the reaction mixture followed by extraction (2 X 30 mL) with
dichloromethane. The resulting solution was evaporated to dryness and the residues
were purified by column chromatography using hexane/ethyl acetate 90/10 as eluent.
5.1.1.1. Synthesis of ligand L-CS
20

The ligand was prepared and purified using the general procedure described
above; naphthalene-2-thiol (RSH) (160 mg, 1 mmol); NaH (28 mg, 1.1 mmol) and
(bromomethyl)benzene (170 mg, 1 mmol). Yield 90% (225 mg). White solid, melting
point: 70-72°C. 1H NMR (CDCl3, 300 MHz): δ 7.62-7.73 (m, 4H, naph), 7.31-7.41 (m,
13
3H, bz, naph), 7.14-7.27 (m, 5H, bz, naph), 4.15 (s, 2H, CH2). C{1H} NMR (CDCl3,
75 MHz): δ 137.3 (bz)., 134.2 (naph), 133.4 (naph), 132.5 (naph), 129.0 (naph), 128.8
(naph), 128.5 (bz), 127.8 (naph), 127.7 (Bz), 127.5 (naph), 126.7 (naph), 126.5 (naph),
126.2 (bz), 125.6 (naph), 38.9 (CH2). EI-MS positive ion; Calc. 250.36 g/mol; Found.
250 m/z [M]+.
5.1.1.2. Synthesis of ligand L-SN
The ligand was prepared and purified using the general procedure described
above. naphthalene-2-thiol (RSH) (160 mg, 1 mmol); NaH (28 mg, 1.1 mmol) and 2-
(bromomethyl)pyridine (172 mg, 1 mmol). Yield 90% (155 mg). White solid, melting
1
3
point: 53-55 °C. H NMR (CDCl3, 300 MHz):  8.47 (d, JHH= 4.2 Hz, 1H, py), 7.56-
3
7.70 (m, 5H, py, naph), 7.32-7.40 (m, 4H, py, naph), 7.14 (t, JHH= 6.9 Hz, 1H, naph),
13
4.37 (s, 2H, CH2), C{1H} NMR (CDCl3, 75 MHz): δ 157.4 (py), 149.0 (py), 137.0
(py), 133.7 (naph), 133.2 (naph), 131.9 (naph), 128.4 (naph), 127.7 (naph), 127.6
(naph), 127.5 (naph), 127.2 (naph), 126.5 (naph), 125.8 (naph), 123.1 (py), 122.2 (py),
46.6 (CH2), EI-MS positive ion; Calc. 251.35 g/mol; Found. 251 m/z [M]+.
5.1.1.3. Synthesis of ligand L-SCS
The ligand was prepared and purified using the general procedure described
above. naphthalene-2-thiol (RSH) (160 mg, 1 mmol); NaH (28 mg, 1.1 mmol) and 1,3-
bis(bromomethyl)benzene (132 mg, 0.5 mmol). Yield 95 % (400 mg). White solid,
21

1
melting point: 116-118°C. H NMR (CDCl3, 300 MHz):  7.67-7.70 (m, 2H, naph),
3
7.58-7.62 (m, 6H, naph), 7.34-7.36 (m, 4H, naph), 7.26 (d, JHH = 6 Hz, 2H, bz), 7.24
(s, 1H, bz) , 7.10 (s, 3H, bz, naph), 4.07 (s, 4H, CH2). 13C{1H} NMR (CDCl3, 75 MHz):
δ 137.7 (bz), 133.74 (naph), 133.71 (naph), 131.9 (naph), 129.4 (bz), 128.7 (naph),
128.35 (naph), 127.85 (naph), 127.81 (bz), 127.78 (naph), 127.71 (bz), 126.4 (naph),
125.7 (naph), 38.8 (CH2). EI-MS positive ion: Calc. 422.6 g/mol; Found. 422 m/z [M]+.
5.1.1.4. Synthesis of ligand L-SNS
The ligand was prepared and purified using the general procedure described
above. naphthalene-2-thiol (RSH) (160 mg, 1 mmol); NaH (28 mg, 1.1 mmol) and 2,6-
bis(bromomethyl)pyridine (133 mg, 0.5 mmol). Yield 92 % (390 mg). White solid,
1
melting point: 84-86°C. H NMR (CDCl3, 300 MHz):  7.66-768 (m, 4H, naph), 7.56-
3
7.61 (m, 4H, naph), 7.41 (t, JHH= 7.8 Hz, 1H, py.), 7.30-7.36 (m, 6H, naph), 7.11 (d,
3JHH = 7.8 Hz, py.), 4.33 (s, 4H, CH2). 13C{1H} NMR (CDCl3, 75 MHz): δ 156.7 (py),
138.5 (naph), 133.6 (py), 132.6 (naph), 131.9 (naph), 128.5 (naph.), 127.9 (naph.),
127.6 (naph.), 127.5 (naph), 127.3 (naph), 126.7 (naph), 125.9 (naph), 121.9 (py.), 39.1
(CH2). EI-MS positive ion: Calc. 423.59 g/mol; Found. 423 m/z [M]+. Anal. Calcd for
C27H21NS2 (423.59 g/mol): C, 76.56; H, 5.00; N, 3.31. Found: C, 76.49; H, 5.04; N,
3.29.
5.1.1.5. Synthesis of ligand L-SNS-O
The ligand was prepared and purified using the general procedure described
above. naphthalene-2-thiol (RSH) (160 mg, 1 mmol); NaH (28 mg, 1.1 mmol) and
pyridine-2,6-dicarbonyl dichloride (102 mg, 0.5 mmol). Yield 93 % (420 mg). White
solid, melting point: 168-170°C. 1H NMR (CDCl3, 300 MHz): δ 8.12 (d, 3JHH= 7.5 Hz,
22

3
3
2H, py), 8.05 (s, 2H, naph), 7.99 (t, JHH= 7.8 Hz, 1H, py), 7.87 (d, JHH= 8.7 Hz, 2H,
3
naph), 7.79-7.84 (s, 4H, naph), 7.65 (d, JHH= 8.7 Hz, 2H, naph), 7.44-7.51 (s, 4H,
13
naph). C{1H} NMR (CDCl3, 75 MHz): 191.4 (C=O), 150.9 (py), 139.2 (py), 134.9
(naph), 133.7 (naph), 133.5 (naph), 131.2 (naph), 128.9 (naph), 128.0 (naph), 127.9
(naph), 127.2(naph), 126.6(naph), 125.2 (naph), 124.5 (py). EI-MS positive ion: Calc.
451.56 g/mol; Found. 451 m/z [M]+. Anal. Calcd for C27H17NO2S2 (451.56 g/mol): C,
71.82; H, 3.79; N, 3.10. Found: C, 71.94; H, 3.75; N, 3.12.
5.2. Synthesis of palladium complexes (Pd-CS, Pd-NS, Pd-SCS, Pd-SNS, Pd-SNS-O)
5.2.1 Organometallic compounds (Pd-CS and Pd-SCS). General procedure A.
[PdCl2(MeCN)2] (0.1 mmol) was added to a solution of the corresponding ligand
(L-CS or L-SCS) (0.1 mmol) and sodium acetate (0.11 mmol) in acetonitrile (50 mL).
The reaction mixture was stirred and refluxed for 48 h. After this time, the solution was
filtered, and the resulting solution evaporated to dryness. The residues were purified by
column chromatography using hexane/ethyl acetate 70:30 as eluent leading to the pure
compounds.
5.2.1.1 Synthesis of complex Pd-CS
The complex was prepared using the general procedure A for the organometallic
palladium complexes (5.2.1). [PdCl2(MeCN)2] (26 mg, 0.1 mmol), ligand L-CS (25 mg,
0.1 mmol) and sodium acetate (65 mg, 0.11 mmol) in acetonitrile (50 mL), refluxed for
48 h. Yield 75 % (58 mg). Red solid, melting point: 140-141°C. 1H NMR (CDCl3, 300
MHz): δ 8.26 (s, 2H, naph), 7.66-7.88 (m, 8H, naph), 7.38-7.52 (m, 4H, Naf.), 7.23 (s,
13
2H, Ar.), 6.81-6.93 (m, 6H, Ar.), 4.51 (s, 2H, CH2), 4.19 (s, 2H, CH2). C{1H} NMR
(CDCl3, 75 MHz): 171.2 (bz), 148.5 (bz), 147.1 (bz), 135.8 (naph), 133.6 (naph), 133.0
23

(naph), 132.2 (naph), 129.7 (naph), 128.6 (naph), 128.4 (bz), 128.3 (bz), 127.8 (naph),
127.2 (naph), 126.2 (naph), 125.3 (naph), 123.2 (naph), 50.9 (CH2), ESI-MS positive
ion: Calc. 782.45g/mol; Found. 784 m/z [M+H]+. Anal. Calcd for C34H26Cl2Pd2S2
(782.45g/mol): C, 52.19; H, 3.35. Found: C, 52.15; H, 3.31.
5.2.1.2. Synthesis of complex Pd-SCS
The complex was prepared using the general procedure A for organometallic
palladium complexes (5.2.1). [PdCl2(MeCN)2] (26 mg, 0.1 mmol), ligand L-SCS (42
mg, 0.1 mmol) and sodium acetate (65 mg, 0.11 mmol) in acetonitrile (50 mL), refluxed
1
for 48 h. Yield 70% (40 mg). Yellow solid, melting point: 188-190°C. H NMR
(CDCl3, 300 MHz): δ 8.24 (s, 2H, naph), 7.70-7.83 (m, 8H, naph), 7.40-7.47 (m, 4H,
13
naph), 6.98 (s, 1H, bz), 6.95 (s, 2H, bz), 4.63 (s, 4H, CH2). C{1H} NMR (CDCl3, 75
MHz):  161.4 (bz), 149.5 (naph), 133.4 (naph), 133.2 (bz), 131.2 (naph), 129.8 (naph),
129.2 (naph), 128.2 (naph), 127.6 (bz), 127.1 (naph), 125 (naph), 122.3 (naph), 51.7
(CH2). FAB-MS positive ion: Calc. 563.47 g/mol; Found. 527 m/z [M-Cl]+. Anal.
Calcd for C28H21ClPdS2 (563.47 g/mol): C, 59.68; H, 3.76. Found: C, 59.63; H, 3.70.
5.2.2 Coordination compounds (Pd-NS, Pd-SNS and Pd-SNS-0). General procedure B:
To a solution of the corresponding ligand (L-SN, L-SNS, L-SNS-O) (ca. 0.1
mmol) in dichloromethane (30 mL) was added 1 equivalent of [PdCl2(MeCN)2] and the
resulting solution was stirred for 2 h at room temperature. After this time, the solution
was filtered and the resulting solid was washed with a mixture of hexane/ethyl acetate
7:3 (2 x 10 mL) (Pd-SN, Pd-SNS) or dichloromethane (Pd-SNS-O) yielding the pure
palladium complexes.
24

5.2.2.1 Synthesis of complex Pd-NS
The complex was prepared using the general procedure B for coordination
palladium complexes (5.2.2). [PdCl2(MeCN)2] (26 mg, 0.1 mmol) and ligand L-NS (25
mg, 0.1 mmol) in CH2Cl2 (30 mL), room temperature for 48 h. Yield 97 % (41 mg).
1
3
Yellow solid, decomposed at: 220°C. H NMR (CDCl3, 300 MHz): δ 9.24 (d, JHH= 6
Hz, 1H, py), 8.33 (s, 1H, naph), 7.88-7.94 (m, 1H, py), 7.75-7.85 (m, 4H, naph), 7.64
2
(d, J = 7.8 Hz, 1H, Py), 7.47-7.56 (m, 2H, naph), 7.39-7.43 (m, 1H, py.), 5.13 (d, JHH
=18 Hz, 1H, CH2), 4.73 (d, 1H, 2JHH= 15 Hz, CH2.). 13C{1H} NMR (CDCl3, 75 MHz):
 162.0 (py), 151.6 (py), 139.7 (naph), 132.9 (naph), 132.4 (naph), 130.4 (py), 129.5
(py), 127.7 (naph), 127.5 (naph), 127.4 (naph), 127.2 (Naf.), 125.9 (Py.), 125.6 (naph),
124 (naph), 123.5 (naph), 45.6 (CH2). ESI-MS positive ion: Calc. 428.67 g/mol; Found.
468 m/z [M+K]+. Anal. Calcd for C16H13Cl2NPdS2 (428.67 g/mol): C, 44.83; H, 3.26;
N, 3.27. Found: C, 44.93; H, 3.36; N, 3.21.
5.2.2.2. Synthesis of complex Pd-SNS
The complex was prepared using the general procedure B for coordination
palladium complexes (5.2.2). [PdCl2(MeCN)2] (26 mg, 0.1 mmol) and ligand L-SNS
(42 mg, 0.1 mmol) in CH2Cl2 (30 mL), room temperature for 48 h. Yield 93 % (56 mg).
Orange solid, melting point: 200°C. 1H NMR (CDCl3, 300 MHz):  8.40 (s, 2H, naph),
8.09 (t, 3JHH= 7.8 Hz, 1H, py.), 7.78-7.93 (m, 10H, py, naph), 7.52-7.62 (m, 4H, naph),
13
5.44 (s, 4H, CH2). C{1H} NMR (CDCl3, 75 MHz):  167.6 (py), 145.9 (py), 138.3
(naph), 137.9 (naph), 135.6 (naph), 135.2 (naph), 133.4 (naph), 133.1 (naph), 132.8
(naph), 132.7 (naph), 131.3 (naph), 130.8 (naph), 128.4 (py), 54.5 (CH2). ESI-MS
positive ion: Calc. 600.92 g/mol; Found. 565 m/z [M-Cl]+. Anal. Calcd for
25

C27H21Cl2NPdS2 (600.92 g/mol): C, 54.37; H, 3.52; N, 2.33. Found: C, 54.35; H, 3.56;
N, 2.37.
5.2.2.3. Synthesis of complex Pd-SNS-O
The complex was prepared using the general procedure B for coordination
palladium complexes (5.2.2). [PdCl2(MeCN)2] (26 mg, 0.1 mmol) and ligand L-SNS-O
(45 mg, 0.1 mmol) in CH2Cl2 (30 mL), room temperature for 48 h. Yield 87 % (55 mg).
1
Red solid, decomposed at: 200 °C. H NMR (CD3CO, 300 MHz):  8.47 (s, 2H, py),
8.46 (s, 2H, naph), 8.44 (s, 8H, py, naph), 8.39 (s, 1H, naph), 8.34 (m, 4H, naph).
13C{1H} NMR (CDCl3, 75 MHz):  190.2 (C=O), 149.2 (py), 139.8 (py), 134.1 (naph),
133.6 (naph), 133.5 (naph), 130.9 (naph), 128.2 (naph), 127.1 (naph), 127.5 (naph),
126.9 (naph), 126.5 (naph), 125.0 (naph), 123.9 (py). ESI-MS positive ion: Calc.
628.89 g/mol; Found. 593 m/z [M-Cl]+. Anal. Calcd for C27H17Cl2NO2PdS2 (628.89
g/mol): C, 54.65; H, 3.75; N, 2.36. Found: C, 54.56; H, 3.74; N, 2.38.
5.3. Catalytic experiments
5.3.1 General procedure for Suzuki-Miyaura cross-coupling
Suzuki-Miyaura cross-couplings were carried out in 10 mL reaction tubes
suitable for using in microwave apparatus equipped with an inner magnetic stirring bar.
5 mL of a DMF/H2O 4:1 solution containing Pd-cat. (0.01 mmol), aryl bromide (1
mmol), PhB(OH)2 (1.2 mmol) and a base (2.4 mmol) was stirred and heated in a
microwave reactor at 100 oC and 100 W for 10 min. After the prescribed reaction time,
the mixture was cooled to room temperature, extracted with CH2Cl2 (3 X 3 mL) and
dried with anhydrous Na2SO4, filtered through celite and analyzed by GC-MS.
26

5.3.2 General procedure for Mizoroki-Heck cross-coupling
A 10 mL reaction tube designed for the monomode microwave equipped with an
inner magnetic stirring bar was loaded with Pd-cat. (0.01 mmol), aryl halide (1 mmol),
styrene (1.2 mmol), base (2.4 mmol) and 5 mL of a DMF/H2O 4:1 mixture, and then,
the reaction mixture was magnetically stirred and heated in a microwave reactor at 100
oC and 100 W for 10 min. After the prescribed reaction time, the mixture was cooled to
room temperature. After the prescribed reaction time, the mixture was cooled to room
temperature, extracted with CH2Cl2 (3 X 3 mL) and dried with anhydrous Na2SO4,
filtered through celite and analyzed by GC-MS.
5.4. Data collection and refinement for compounds L-SNS-O, Pd-CS and Pd-NS.
Crystal suitable of L-SNS-O, Pd-CS and Pd-NS were mounted on glass fibers,
then placed on a Bruker Smart Apex II diffractometer with Mo-target X-ray source
(λ=0.71073 Å). The detector was placed at 5.0 cm from the crystal frames were
collected with a scan width of 0.5 in ω and exposure time of 5 s/frame. 8365, 15414 and
9954 reflections for L-SNS-O, Pd-CS and Pd-NS respectively were collected and
integrated with the Bruker SAINT software package[31] using a narrow-frame
integration algorithm. Systematic absences and intensity statistics were used in
monoclinic system and P2(1)/c space group for Pd-CS, Orthorhombic system and
Cmc21 space group for L-SNS-O and monoclinic system C2/c for Pd-NS. The
structures were solved using Patterson methods using SHELXS-2018 program.[31] The
remaining atoms were located via a few cycles of least squares refinements and
difference Fourier maps. Hydrogen atoms were input at calculated positions and
allowed to ride on the atoms to which they are attached. Thermal parameters were
refined for all hydrogen atoms using a Ueq=1.2 Å. The final cycle of refinement was
27

carried out on all non-zero data using SHELXL-2014/7 [32]. Absorption correction was
applied using SADABS program.[33]
Supplementary information
Supplementary data for compounds L-SNS-O, Pd-CS and Pd-NS 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 1971695-
1971697.
Acknowledgments
We would like to thank Chem. Eng. Luis Velasco Ibarra, Dr. Francisco Javier
Pérez Flores, Q. Eréndira García Ríos, M.Sc. Lucia del Carmen Márquez Alonso, M.Sc.
Lucero Ríos Ruiz, M.Sc. Alejandra Núñez Pineda (CCIQS), Q. María de la Paz Orta
Pérez, Q. Roció Patiño-Maya and Ph.D. Nuria Esturau Escofet for technical assistance.
The financial support of this research by PAPIIT-DGAPA-UNAM (PAPIIT IN207317
and IN210520) and CONACYT A1-S-33933 is gratefully acknowledged.
28

References
1. J.-P. Corbet and G. Mignani, Chem. Rev. 106 (2006) 2651-2710.
2. A. F. Littke and G. C. Fu, Angew. Chem. Int. Ed. 41 (2002) 4176-4211.
3. J. Dupont, C. S. Consorti and J. Spencer, Chem. Rev.105 (2005) 2527-2572.
4. A. Balanta, C. Godard and C. Claver, Chem. Soc. Rev. 40 (2011) 4973-4985.
5. A. Suzuki, Acc. Chem. Res. 15 (1982) 178-184.
6. B. L. Oliveira and O. A. C. Antunes, Lett. Org. Chem. 4 (2007)13-15.
7. N. Miyaura and A. Suzuki, Chem. Rev. 95 (1995) 2457-2483.
8. M. Ohff, A. Ohff, M. E. van der Boom and D. Milstein, J. Am. Chem. Soc. 119
(1997) 11687-11688.
9. J. Aydin, J. M. Larsson, N. Selander and K. J. Szabó, Org. Lett. 11 (2009) 2852-
2854.
10. D. Morales-Morales, R. Redon, C. Yung and C. M. Jensen, Chem. Commun. (2000)
1619-1620.
11. E. Peris, J. A. Loch, J. Mata and R. H. Crabtree, Chem. Commun. (2001) 201-202.
12. J. L. Bolliger and C. M. Frech, Adv. Synth. Catal. 352 (2010) 1075-1080.
13. A. F. Littke, C. Dai and G. C. Fu, J. Am. Chem. Soc. 122 (2000) 4020-4028.
14. X. Bei, H. W. Turner, W. H. Weinberg, A. S. Guram and J. L. Petersen, J. Org.
Chem. 64 (1999) 6797-6803.
15. G. Chessa, L. Canovese, F. Visentin and P. Uguagliati, Inorg. Chem. Commun. 2
(1999) 607-608.
16. L. Canovese, G. Chessa, F. Visentin and P. Uguagliati, Coord. Chem. Rev. 248
(2004) 945-954.
17. L. Canovese, F. Visentin, G. Chessa, P. Uguagliati, C. Santo and A. Dolmella,
Organometallics 24 (2005) 3297-3308.
29