Synthesis and structural characterization of palladium(II) 2-(arylazo)naphtholate complexes and their catalytic activity in Suzuki and Sonogashira coupling reactions

Article abstract of DOI:10.1080/00958972.2019.1623394

A family of five palladium(II) 2-(arylazo)naphtholate complexes, [PdCl(PPh₃)(L)] (L = O, N-donor of bidentate 2-(arylazo)naphtholate ligands), have been synthesized and characterized by elemental analysis and spectral (FT-IR, UV–Vis, ¹H-NMR and ¹³C-NMR) methods. Further, the catalytic efficiency of all the complexes have been investigated for Suzuki and Sonogashira coupling reaction of various aryl halides.

Full text of DOI:10.1080/00958972.2019.1623394

Journal of Coordination Chemistry
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Synthesis and structural characterization of
palladium(II) 2-(arylazo)naphtholate complexes
and their catalytic activity in Suzuki and
Sonogashira coupling reactions
Sathya Munusamy, Premkumar Muniyappan & Venkatachalam Galmari
To cite this article: Sathya Munusamy, Premkumar Muniyappan & Venkatachalam Galmari
(2019): Synthesis and structural characterization of palladium(II) 2-(arylazo)naphtholate complexes
and their catalytic activity in Suzuki and Sonogashira coupling reactions, Journal of Coordination
Chemistry, DOI: 10.1080/00958972.2019.1623394
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JOURNAL OF COORDINATION CHEMISTRY
https://doi.org/10.1080/00958972.2019.1623394
Synthesis and structural characterization of palladium(II)
2-(arylazo)naphtholate complexes and their catalytic
activity in Suzuki and Sonogashira coupling reactions
Sathya Munusamy, Premkumar Muniyappan and Venkatachalam Galmari
PG & Research Department of Chemistry, Government Arts College, Dharmapuri, India
ABSTRACT
ARTICLE HISTORY
Received 15 September 2018
Accepted 8 May 2019
A family of five palladium(II) 2-(arylazo)naphtholate complexes,
[PdCl(PPh3)(L)] (L ¼ O, N-donor of bidentate 2-(arylazo)naphtholate
ligands), have been synthesized and characterized by elemental
analysis and spectral (FT-IR, UV–Vis, 1H-NMR and 13C-NMR) meth-
ods. Further, the catalytic efficiency of all the complexes have
been investigated for Suzuki and Sonogashira coupling reaction
of various aryl halides.
KEYWORDS
Palladium(II) complexes; azo
ligands; characterization;
catalyst; Suzuki;
Sonogashira cou-
pling reaction
1. Introduction
Coordination chemistry has traditionally emphasized the design and preparation of
ligands which are able to control the electronic as well as steric properties of transi-
tion metal ions. There has been considerable interest in palladium complexes largely
because of their potential catalytic and biological applications [1, 2]. As properties of
such complexes depend primarily on the coordination environment around palladium,
complexation by ligands of selected types is important.
CONTACT Galmari Venkatachalam
gvchem@gmail.com
PG & Research Department of Chemistry, Government
Arts College, Dharmapuri, Tamilnadu 636 705, India
Supplemental data for this article is available online at https://doi.org/10.1080/00958972.2019.1623394.
ß 2019 Informa UK Limited, trading as Taylor & Francis Group

2
M. SATHYA ET AL.
Cat
R-M
R
Suzuki
X
Cat
Sonogashira
R
C
HC
R
Scheme 1. Major classes of metal-catalyzed cross coupling reactions.
The chemistry of azobenzene derivatives has stimulated research directed towards
their use as materials for digital storage, as building blocks in supramolecular devices
and polymer materials [3–5]. Special attention has been paid to complexes with nitrogen
donors such as amines, imines, azo, and heterocyclic compounds as catalysts [6]. Several
studies have been published on the synthesis and spectral properties of azodyes [7–9],
reflecting their important applications in polyester fibers [10], disperse dyes [11] as well
as their involvement in many biological reactions and in analytical chemistry [12].
Arylazo ligands provide a great platform in coordination/organometallic chemistry
for development of ligand systems [13]. Most azo ligands are easily accessible using
simple synthetic procedures with selection of an amine and substituted phenol. These
ligands can potentially stabilize metals in different oxidation states which is particu-
larly useful in catalytic reactions [14]. Metal complexes derived from arylazo ligands
have found applications in catalysis [15].
The palladium-catalyzed Suzuki cross coupling of aryl halides with arylboronic acids
is a powerful tool for preparation of unsymmetrical biaryl compounds [16] and has
been applied to many areas, including herbicides [17] and natural product synthesis
[18]. The value of the Suzuki reactions stems from using low-cost and non-toxic chem-
icals, vide substrate tolerance, mild reactions conditions, and easy separation of prod-
ucts from the reaction media [19, 20]. The use of non-flammable inexpensive and
abundant green solvents such as water or water solutions is an important area of
research for the Suzuki reaction [21–23]. Cross coupling reactions involve metal-cata-
lyzed coupling of an organic electrophile with an organic nucleophile (Scheme 1). A
variety of name reactions have been developed using organometallic carbon nucleo-
philes. Examples with nearly every metal in the periodic table have been demon-
strated, but the most common organometallic species used include organotin (Stille),
organoboron (Suzuki), Grignard reagents (Kumada), organosilicon (Hiyama), organozinc
(Negishi) and in situ generated acetylide anions (Sonogashira). Key steps in these
cross-coupling reactions include oxidative addition of the organic halide, trans metala-
tion of the nucleophilic carbon, and reductive elimination to form the products.
The employment of hydrophilic ligands such as N-heterocyclic carbenes (NHCs) or
phosphine ligands is another method of improving the efficiency of Suzuki catalysis in
water. Palladium triaryl phosphine complexes have been the most commonly
employed as catalysts for the Suzuki reactions. Sterically demanding, electron-rich
phosphines, such as tri-t-butylphosphines and its analogs [24], di(t-butyl)aryl and dicy-
clo-hexylarylphosphines [25] have excellent activities in the Suzuki reaction for a var-
iety of substrates. However, despite the wide use in the Suzuki reactions phosphines

JOURNAL OF COORDINATION CHEMISTRY
3
O
PPh3
Cl
OH
Pd
CHCl3/Et3N
Reflux/4h
N
N
N
PdCl2(PPh3)2
+
N
R
R
R = H (L1, 1); CH3 (L2, 2); OCH3 (L3, 3);
NO2 (L4, 4); Br (L5, 5)
R = H (HL1); CH3 (HL2); OCH3 (HL3);
NO2 (HL4); Br (HL5)
Scheme 2. Synthesis of Pd(II) 2-(arylazo)naphtholate complexes.
have several disadvantages, including toxicity, sensitivity to air and moisture, and diffi-
cult separation from the products. As a result, NHCs have emerged as an alternative
to phosphine ligands [26–32]. The unique steric and electronic properties of NHCs as
well as their specific coordination chemistry (strong O-donor and weak p-acceptor
properties) contribute to the generation of highly active and stable metal centers in
the key catalytic steps of the Suzuki reaction.
Steric bulk of the ligand is believed to increase the rate of reductive-elimination to
regenerate the active catalyst. Despite the bulky ligand increasing the reductive elimin-
ation rate, the rate of the oxidative addition step can be dramatically affected by the
increasing size of the ligand. According to these points a balance between the steric and
electronic properties of the ligand is an essential requirement. Though many reports are
available on azo ligands with ruthenium and osmium, less research has been reported
for palladium(II) arylazo complexes. We are therefore interested in continuing our stud-
ies on synthesis of catalysts derived from inexpensive and easily synthesized ligand sets.
As a continuation of our work [33] in designing new O, N donor based ligands for
exploring their organometallic chemistry and catalytic activity in organic transforma-
tions [34], herein we report the synthesis and structural characterization of
palladium(II) complexes containing 2–(arylazo)naphtholate ligands and their catalytic
activity in Suzuki and Sonogashira coupling reactions of various aryl halides.
2. Experimental methods
2.1. Materials
All chemicals used were chemically pure and AR grade. Solvents were purified and
dried according to standard procedure. PdCl2(PPh3)2 was purchased from Arora
Matthey and used without purification. Triethylamine, aniline, p-substituted aniline and
2-naphthol were purchased from Sigma Aldrich. Other chemicals (used in catalytic
studies) were purchased from Merck and Aldrich. The 2-(arylazo)naphtholate ligands
were prepared according to literature methods [35].

4
M. SATHYA ET AL.
2.2. Physical measurements
Analyses of carbon, hydrogen and nitrogen were performed on elementary system
1
model vario EL111 at Sophisticated Test and Instrumentation Center, Cochin, India. H-
and 13C-NMR spectra were recorded in the Sophisticated Test and Instrumentation
Centre (STIC), Cochin University of Science and Technology, Kochi. FT-IR spectra of the
complexes were recorded in a CARY 360, Agilent resolution pro spectrophotometer
from 4000 to 400 cmꢀ1. Electronic spectra of the complexes were recorded in CHCl3
solution with a Cary 300 Bio UV–Vis Varian spectrophotometer from 800 to 200 nm
using cuvettes of 1 cm path length. Melting points are uncorrected and were deter-
mined in capillary tubes on a Boetius micro heating apparatus.
2.3. Synthesis of Pd(II) 2-(arylazo)naphtholate complexes
All the new complexes were prepared by the following general procedure. To an etha-
nol solution of 1:1 ratio of 2-(p-arylazo)naphtholate ligands (1 mmol, 0.037–0.047 g)
was added [Pd(PPh3)2Cl2] (1 mmol, 0.1 g) in CHCl3. The resulting reaction mixture was
then heated at reflux for 4 h to yield a reddish-purple solution. The solid mass thus
obtained was subjected to purification by thin layer chromatography on a silica plate.
Chloroform was used as eluent and a reddish purple band separated which was
extracted with 1:1 dichloromethane–chloroform and evaporation of this extract gave
[PdCl(PPh3)(L1–5)] as dark pink crystalline solids.
2.4. General procedure for coupling reactions of aryl halides with boronic acid
(Suzuki coupling reaction)
In a two-necked flask under an atmosphere of nitrogen was placed palladium com-
plexes (1–5) (1 mol%), bromobenzene (0.5 mmol), aryl boronic acid (0.75 mmol) and
K2CO3 (1 mmol). The mixture was then refluxed at 80 ꢁC for 2 h. The progress of the
reaction was monitored by TLC. After completion of the reaction, the solvent was
removed under reduced pressure and the resulting product was diluted with water
(10 ml) and Et2O (10 ml), followed by extraction twice (2 ꢂ 6 ml) with Et2O. The com-
bined organic fraction was dried over MgSO4. The crude product was purified by col-
umn chromatography by using hexane as eluent.
2.5. General procedure for Sonogashira coupling reactions
To a slurry of aryl halide (0.5 mmol) palladium catalyst (0.3 mol%) in an appropriate
solvent (5 ml), phenylacetylene (0.75 mmol) and K2CO3 (1.25 mmol) were added and
heated at required temperature. After completion of the reaction (monitored by TLC),
the flask was removed from the oil bath and water (20 ml) added, followed by extrac-
tion with ether (4 ꢂ 10 ml). The combined organic layers were washed with water
(3 ꢂ 10 ml), dried over anhydrous Na2SO4 and filtered; solvent was removed under vac-
uum. The residue was dissolved in hexane and analyzed by GC–MS using Elite-5 col-
umns, which are fused silica capillary columns coated with 5% diphenyl and 95%
dimethyl polysiloxane.

JOURNAL OF COORDINATION CHEMISTRY
5
Table 1. Elemental analyses, IR and UV–Vis spectral data of Pd(II) 2-(arylazo)naphtho-
late complexes.
Elemental analysis found (calculated)%
IR (cm–1
tN ¼ N tPPh3 tC–O
)
UV–Vis (nm)
Complexes
C
H
N
kmax
[PdCl(PPh3)(L1)] (1) 72.00 (72.48) 4.12 (4.35)
[PdCl(PPh3)(L2)] (2) 72.68 (72.85) 4.63 (4.62)
[PdCl(PPh3)(L3)] (3) 68.76 (68.91) 4.38 (4.42)
[PdCl(PPh3)(L4)] (4) 55.54 (55.88) 2.89 (3.02)
5.25 (5.20)
4.98 (4.95)
4.71 (4.70)
4.05 (4.09)
1409
1408
1436
1433
1401
1455
1465
1460
1474
1479
1298 460a 340b 235c
1300 470a 335b 240c
1296 465a 345b 230c
1335 450a 330b 230c
1307 455a 350b 225c
[PdCl(PPh3)(L5)] (5) 59.01 (59.13) 3.07 (3.22) 12.90 (12.94)
aLMCT transition.
ꢃ
bn–p
cp–p .
ꢃ
3. Results and discussion
The reaction of 2-(p-arylazo)naphtholate ligands (HL1–5) with [Pd(PPh3)2Cl2] proceeds
smoothly in refluxing ethanol/chloroform in the presence of triethylamine to afford
the expected mixed-ligand palladium complexes [PdCl(PPh3)(L)] (L ¼ bidentate 2-(aryla-
zo)naphtholate ligands) as shown in Scheme 2. The choice of substituents (R-groups)
in 2-(arylazo)naphtholate ligands allows for fine tuning of electronic properties which
may influence the resulting metal complex properties.
All the new palladium(II) complexes are highly colored, stable in air, non-hygro-
scopic and highly soluble in common solvents such as dichloromethane, chloroform,
etc., The analytical data are listed in Table 1 and are in agreement with general
molecular formulas proposed for all the complexes.
3.1. IR spectra
The IR spectral data of HL1–5 and their metal complexes are given in Table 1. Infrared
spectra of the complexes show multiple bands of varying intensities from 4000 to
400 cmꢀ1. No attempt has been made to assign each individual band to a specific
vibration. However, the infrared spectra of all the ligands exhibit bands around
1444–1480 cmꢀ1 and 1242–1264 cmꢀ1 corresponding to azo t(N ¼ N–) and phenolic
t(C–O) stretching frequencies, respectively. On complexation t(N ¼ N–) appears at
lower frequency (1401–1436 cmꢀ1) and this red shift supports the coordination of
N(azo) to palladium ion [36]. The band corresponding to phenolic t(C–O) stretch is
shifted to higher frequency (1296–1335 cmꢀ1) in all the complexes, confirming that
the other coordination site is the phenolic oxygen [15]. The complexes exhibit a band
around 1490–1465 cmꢀ1 due to triphenylphosphine ligands (see Figures S1–S10, in
supplementary materials).
3.2. Electronic spectra
The electronic spectra of the complexes have been recorded in CHCl3 and display four
intense absorptions from 800 to 200 nm. The electronic spectral data of all the com-
plexes are listed in Table 1 and a representative spectrum is shown in Figure 1 (all
other spectra are provided in the Figures S11–S14, in supplementary materials). The
absorption bands around 550 nm have been assigned to ligand to metal charge

6
M. SATHYA ET AL.
Figure 1. UV-Vis spectrum of [PdCl(PPh3)(L2)] (2).
transfer transitions taking place from the filled ligand (HOMO) orbital to the singly
ꢃ
occupied palladium t2 orbital (HOMO). The bands at 320–390 nm are due to n–p tran-
sitions of non-bonding electrons present on the nitrogen of the arylazo group in the
ꢃ
palladium(II) complexes. The band observed around 220–240 nm is assigned to p–p
transitions of the ligands. The patterns of the electronic spectra of all the complexes
indicate the presence of square planar palladium(II) [37].
1
3.3. H- and 13C-NMR spectra
1H-NMR spectra of the complexes were recorded in CDCl3 at room temperature. The
1
characteristic signals in the H-NMR spectra are given in Table 2 and a representative
spectrum is given in Figure 2 (all the other spectra are in the Figures S15–S17, in sup-
plementary materials). The signal as a multiplet in the spectra of all the complexes
observed at 6.2–8.4 ppm have been assigned to the aromatic protons of triphenyl-
phosphine and 2-(arylazo)naphtholate ligands. Methyl protons are singlets at d 2.
49 ppm and the methoxy protons are singlets at 3.93 ppm, due to 2 and 3, respect-
ively. 13C-NMR spectra of 1 and 2 were recorded. The –CH3 carbon peak appeared at
d 15.01 ppm for 1. The methoxy carbon signal (OCH3) was observed for 2 at d 55.
34 ppm. The 13C-NMR spectra are shown in Figures S18 and S19 (see
Supplementary materials).
3.4. Catalytic Suzuki cross coupling reactions
The palladium(II) complexes were screened for their catalytic activity in C–C coupling
reactions. The results obtained are given in Table 3. We have also investigated the
effects of catalyst loading on the coupling of bromobenzene with phenylboronic acid
in order to optimize the reaction conditions. It is significant to accomplish good yields
using minimum amounts of catalysts 0.01 mmol and K2CO3 as base and methanol as

JOURNAL OF COORDINATION CHEMISTRY
7
1
Table 2. The H-NMR spectral data of Pd(II) 2-(arylazo)naphtholate complexes.
Complexes
1H-NMR data (d; ppm)
[PdCl(PPh3)(L1)] (1)
[PdCl(PPh3)(L2)] (2)
[PdCl(PPh3)(L3)] (3)
[PdCl(PPh3)(L4)] (4)
[PdCl(PPh3)(L5)] (5)
7.06–8.36(Ar, m)
6.61–8.44(Ar, m), 2.49(CH3, s)
6.66–8.43(Ar, m), 3.93(OCH3, s)
6.23–8.36(Ar, m)
6.53–8.23(Ar, m)
Figure 2. 1H-NMR spectrum of [PdCl(PPh3)(L2)] (2).
solvent. The obtained results were promising and all the complexes have
good activity.
To optimize the catalyst loading, it is preferable to use a small amount of catalyst and
achieve a high yield in the Suzuki cross coupling reactions. Recently, it was reported that
high catalyst loading leads to active black Pd formation and also inhibits catalytic cycles.
Our reaction worked well with different catalyst ratios and the reaction of bromobenzene
with phenyl boronic acid furnished good yield when 1 mol% of catalyst was loaded. We
have chosen (1 mol %) catalyst [PdCl(PPh3)(L1) loading as the best conditions for further
coupling reactions (see Supporting Information: effect of catalyst loading Table S1, in sup-
plementary materials). To select the most suitable solvents in our catalytic system, we
chose the reaction between bromobenzene with boronic acid in the presence of various
solvents MeOH, CH3CN, DMF/H2O (2:1) and (1:2), CH2Cl2 and ethanol. Methanol gives an
excellent yield of 82% and the poor one is acetonitrile with yield of 52%. In DMF/H2O (2:1),
MeOH/H2O (2:1), CH2Cl2 and ethanol, the yields are 79%, 81%, 54%, and 70%, respectively.
The catalytic activity of the Pd(II) 2-(arylazo)naphtholate complexes were investi-
gated under the same reaction conditions. To survey the generality of the catalytic
protocol, we investigated the reaction using various aryl halides coupled with

8
M. SATHYA ET AL.
Table 3. Suzuki carbon–carbon coupling reaction of aryl bromides with phenylboronic acida.
Pd(II) Complexes (1-5)
1 mol%
+
R
Br
B(OH)2
R
K2CO3, MeOH / reflux / 2h
R= H, CH3, OCH3, NO2, OH, CN
R= H, CH3, OCH3, NO2, OH, CN
Complexes (catalyst)
1
2
3
4
5
Entry
1
Aryl halide
Yield (%)b
82
79
76
59
71
50
54
63
76
2
3
4
5
66
71
56
58
78
72
60
60
78
73
30
61
61
67
60
55
6
7
8
9
86
76
38
88
82
64
45
83
89
55
39
78
92
67
41
82
90
50
37
91
aReaction conditions: 0.5 mmol of bromobenzene, 0.75 mmol of phenylboronic acid, 1 mmol of K2CO3, 1 mol%
of catalyst.
bIsolated yield after column chromatography.
arylboronic acids under the optimized conditions. The results are summarized in Table
3. When benzene boronic acid was coupled with aryl bromides containing both elec-
tron-donating and electron-withdrawing groups in the para position, the correspond-
ing products were obtained in moderate yields. The ortho substituted aryl bromide (2-

JOURNAL OF COORDINATION CHEMISTRY
9
Pd(+2)
16e-ns
Pd(0)
14e-ns
=
=
Pd(+2)
16e-ns
Pd(0)
14e-ns
O
N
PPh3
Cl
Pd
Br
N
Oxidative
addition
Reductive
elimination
R
O
N
PPh3
O
N
PPh3
Cl
Pd
Pd
Cl
N
Br
N
Transmetallation
R
R
Ar, B(OH)3
Br, B(OH)3
Scheme 3. Probable mechanism for the observed Suzuki cross coupling reaction by [PdCl(PPh3)(L)].
Table 4. Optimization of reaction conditionsa.
Complex 2
+
Br
Solvent, Base
Entry
Solvent
Base
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
Et3N
K2CO3
Pyrolidine
K2CO3
K2CO3
Temp. ꢁC
Catalyst loading (complex mol%)
Time (h)
Yieldb (%)
1
2
3
4
5
6
7
8
9
Toluene
Acetone
MeCN
DMSO
DMF
Ethanol
Ethanol
Ethanol
Ethanol
Ethanol
80
100
80
100
78
78
80
80
78
78
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.2
0.1
0.4
9
8
10
8
8
6
6
6
6
35
46
40
58
66
70
85
64
79
92
10
6
aReaction conditions: bromobenzene (0.5 mmol), phenylacetylene (0.75 mmol), base (1.25 mmol), solvent (5 ml), cata-
lyst (0.3 mol%), temperature (80 ꢁC).
bIsolated yield after column chromatography.
bromotoluene, Table 3; entry 5) gave the corresponding products in slightly lower
yield, perhaps due to steric effects.
The coupling reactions of two electron rich arylboronic acids with various aryl bro-
mides (Table 3, entries 1–4) afforded the corresponding products in lower yields than

10
M. SATHYA ET AL.
Table 5. Sonogashira reaction of aryl bromide with phenylacetylenea.
Complex 2
Br
+
Ethanol, K2CO3
R
R
Entry
1
Aryl halides
Product
Yieldb (%)
85
2
3
4
5
6
7
93
74
69
87
75
82
aAryl bromide (0.5 mmol), phenylacetylene (0.75 mmol), catalyst complex 2 (0.3 mol%), ethanol (5 mL), K2CO3
(1.25 mmol), temperature 80 ꢁC.
bIsolated yield based on column chromatography.
those of the benzene boronic acid. Also, coupling reactions of aryl chlorides with ben-
zene boronic acid gave good conversions for all the substrates in 2 h. As expected, sat-
isfactory results were obtained for all electron deficient substrates in the boronic acid
(entry 6). Further, chlorobenzonitrile can also react with phenylboronic acid with good
conversions. The catalytic activity of the present complexes is good and although sev-
eral catalytic systems have been reported, a catalyst of this type is new for its biden-
tate O, N-donor environment with the palladium center (Scheme 3).
3.5. Catalytic Sonogashira cross coupling reactions
Our first approach was to optimize reaction conditions for the reaction between bro-
mobenzene and phenylacetylene as a model reaction. The results are summarized in
Table 4. We used a variety of solvents (Table 4, entries 1–6). All the solvents gave
good conversion but excellent results were obtained with ethanol.
Ethanol also helped in decreasing the leaching of 2 (Table 4, entry 7). Toluene or
acetonitrile gave lower product yields (Table 4, entries 1–3). Sonogashira coupling is
strongly influenced by the nature of the base. We applied several bases (Table 4)
among which K2CO3 gave maximum conversion and selectivity (Table 4, entry 7).
Increase in Pd content from 0.3 mol% to 0.4 mol% did not show any significant

JOURNAL OF COORDINATION CHEMISTRY
11
increase in product yield (Table 4, entries 7 and 10). Therefore, 0.3 mol% Pd loading at
80 ꢁC for 6 h were the optimized reaction parameters for the model reaction (Table 4,
entry 7).
Under these optimized conditions, we carried out substrate study using various
substituted bromobenzene derivatives and phenylacetylene as starting materials. We
tried reaction of both electron-donating as well as electron-withdrawing substituents
of bromobenzene with substituted phenylacetylene which exhibits excellent reactivity
towards 2. The electron-withdrawing substituents (Table 5, entries 2, 5, and 7) gave
greater yield compared to electron-donating groups (Table 5, entries 3, 4, and 6). The
electron-withdrawing groups facilitate the removal of bromo group. The catalyst
showed good activity for electron-donating groups compared to electron-withdrawing
groups (Table 5, Entries 1–7).
4. Conclusion
The present work describes a simple and convenient route to synthesize a new family
of palladium(II) complexes incorporating O, N donors of 2-(arylazo)naphtholate ligands.
The prepared compounds have been characterized by spectroscopic techniques. All
the complexes catalyze Suzuki and Sonogashira type C–C cross coupling reactions of
aryl halides with phenyl boronic acid and phenylacetylene. All the catalytic reactions
proceed under ligand free conditions.
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