Design and synthesis of immobilised orthopalladated catalyst for C–C coupling

Article abstract of DOI:10.1016/j.poly.2018.09.060

The new azo ligand 2-(2-(p-tolyldiazenyl)phenylamino)acetic acid, H₂L, [formulated as H₃CC₆H₄-N = N-C₆H₄-N(H)(CH₂COOH)] was prepared. Reaction of H₂L with Na₂PdCl₄ afforded the orthopalladated mononuclear [(HL)PdCl] complexes. The uncoordinated free dangling carboxylic acid function was recognized and confirmed by X-ray crystallographic studies. The [(HL)PdCl] complex was immobilized on Merrifield resin tethering with the free carboxylic acid function of the complex. Catalytic activity of orthpalladated [(HL)PdCl] complex in homogeneous media and Merrifield supported immobilized complex in heterogeneous phase, toward Suzuki cross-coupling reactions, were examined.

Full text of DOI:10.1016/j.poly.2018.09.060

Accepted Manuscript
Design and synthesis of immobilised orthopalladated catalyst for C-C coupling
Poulami Pattanayak, Sankar Prasad Parua, Surajit Chattopadhyay
PII:
S0277-5387(18)30613-2
https://doi.org/10.1016/j.poly.2018.09.060
POLY 13459
DOI:
Reference:
Polyhedron
To appear in:
Received Date:
Accepted Date:
17 July 2018
20 September 2018
Please cite this article as: P. Pattanayak, S.P. Parua, S. Chattopadhyay, Design and synthesis of immobilised
orthopalladated catalyst for C-C coupling, Polyhedron (2018), doi: https://doi.org/10.1016/j.poly.2018.09.060
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers
we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and
review of the resulting proof before it is published in its final form. Please note that during the production process
errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Revised Mss
Ms. Ref. No.: POLY-D-18-00676
Design and synthesis of immobilised orthopalladated catalyst
for C-C coupling
Poulami Pattanayaka, Sankar Prasad Paruaa and Surajit Chattopadhyaya*
a Department of Chemistry, University of Kalyani, Kalyani 741235
Abstract
The new azo ligand 2-(2-(p-tolyldiazenyl)phenylamino)acetic acid, H2L, [formulated as
H3CC6H4-N = N-C6H4-N(H)(CH2COOH)] was prepared. Reaction of H2L with Na2PdCl4
afforded the orthopalladated mononuclear [(HL)PdCl] complexes. The uncoordinated free
dangling carboxylic acid function was recognized and confirmed by x-ray crystallographic
studies. The [(HL)PdCl] complex was immobilized on Merrifield resin tethering with the free
carboxylic acid function of the complex. Catalytic activity of orthpalladated [(HL)PdCl]
complex in homogeneous media and Merrifield supported immobilized complex in
heterogeneous phase, toward Suzuki cross-coupling reactions, were examined.
Keywords
2-(2-(p-tolyldiazenyl)phenylamino)acetic acid; Pd(II); Orthometallation; Crystal structure;
Heterogeneous catalyst; Suzuki reactions
__________________________________________________________________
*To whom corresponding should be addressed E-mail: scha8@rediffmail.com
1. Introduction
The importance and interest on the organometallic palladium complexes has grown during
the last few decades owing to their involvement in unprecedented chemical transformations,
either as reactive intermediate or as isolable stable precursor [1-8]. Further, the growing
potential of this family of compounds as catalyst for the promotion of significant chemical
reactions has been recognised as one of the fascinating area of chemical research [1-8].
1

Attempts to augment the catalytic efficiency of such orthopalladated complexes have been
continuing in current chemical research. The molecular structure of the reported polymer
anchored active catalysts had subtle uncertainty [9-13]. This work stems from our interest on
synthesis of new catalytically active orthopalladated complexes of azo ligands. Studies on
homogeneous Suzuki and Heck coupling reactions using different kinds of palladium
complexes, incorporating azo ligands, as catalyst have been reported from our research group
[14-18]. Further, we contemplated to prepare ligands and their catalytically active
orthopalladated complexes, suitable for immobilisation on polymer support to fabricate the
catalyst for exploiting those in heterogeneous phase. Polymers containing terminal halo
substituted side chain have been utilised for the purpose of immobilising the catalytically
active complexes through any one of the free - OH / -NH2 or - CO2H functional groups
present in the ligand backbone without changing the coordinating site [19-28].
The ligands were designed in such a manner so that a carboxyl group might hang about in
the ligand framework, after formation of stable orthopalladated complex, for immobilisation
on Merrifield resin as shown in Scheme 1.
Scheme 1
2

Herein we describe the synthesis, characterization and structure of H2L, 1, ligand and its
orthopalladated complex. Immobilization of the new palladium complex on Merrifield resin
and studies on the catalytic behaviour of the new palladium complex in homogeneous and
heterogeneous phases toward C-C coupling reactions have been described in this paper.
2. Experimental
2.1. General consideration
All commercially available chemicals and solvents, utilized in the present work, were of
analytical grade and in most cases these were used as obtained. 2-(p-tolyldiazenyl)aniline
was prepared according to the reported procedure [29]. Ethyl bromoacetate, K2CO3, KOH
were purchased from Sisco Research Laboratories (SRL), India. Chloromethylated
polystyrene was purchased from Aldrich.
Microanalysis (C, H, N) was performed using a Perkin-Elmer 2400 C, H, N, S / O series II
elemental analyzer. Infrared spectra were recorded on a Parkin-Elmer L120-00A FT-IR
spectrometer with the samples prepared as KBr pellets. Electronic spectra were recorded on a
1
Shimadzu UV- 1800 PC spectrophotometer. H NMR spectra were obtained on Brucker 400
NMR spectrometers in CDCl3 using TMS as the internal standard. Surface morphology of
functionalized polystyrene ligand and metal complex were analyzed using a scanning
electron microscope (ZEISS EVO40, England) equipped with EDX facility.
2.2. Synthesis of Ligands
2.2.1. ethyl 2-(2-(p-tolyldiazenyl)phenylamino)acetate
To a solution of the 2-(p-tolyldiazenyl)aniline (2 g, 0.01 mol) in dry acetonitrile (30 mL),
anhydrous K2CO3 (3.45 g, 0.025 mol) and ethyl bromoacetate (1.7g, 0.011 mol) were added.
The mixture was refluxed for 8 h. The progress of the reaction was monitored by TLC. After
filtering the mixture, the solvent of filtrate was removed under reduced pressure and the
orange semi-solid residue was separated by column chromatography on silica gel (60 -120
3

mesh). The eluent was benzene-petroleum ether (8:2). Rf : 0.83. Upon evaporation of the
solvent, the orange solid of pure ligand was obtained. Yield: 2.2g (82%). C17H19N3O2 (297):
calcd.: C 68.67, H 6.44, N 14.13; found: C 68.62, H 6.40, N 14.06. Melting point: 780C. IR
1
(KBr) ν = 3458 (NH), 1465 (N=N), 1740 (C=O). H NMR (400MHz, CDCl3): δ= 9.07 (s,
1H), 7.88-7.81 (m, 3H), 7.30 (d, 3H, J= 8), 6.84 (t, 1H, J=7.4), 6.64 (d, 1H, J=8), 4.31 (q, 2H),
4.08 (d, 2H, J=5.2), 2.42 (s, 3H), 1.33 (t, 3H, J= 7.2). 13C NMR (400MHz, CDCl3): δ 170.31
(s,1C), 150.71 (s,1C), 142.14 (s,1C), 140.35 (s,1C), 136.75 (s, 1C), 132.29 (s,1C), 129.93 (s,1C),
129.75 (s,1C), 122.17 (s,1C), 116.58 (s,1C), 111.64 (s, 1C), 61.48 (s,1C), 45.09 (s, 1C), 21.46 (s,1C),
14.26 (s, 1C). UV-Vis (CH2Cl2): λmax (є, M-1cm-1)= 432 (15099), 322 (24211), 222 (31546).
2.2.2. 2-(2-(p-tolyldiazenyl)phenylamino)acetic acid; H2L, 1
1 g (3.36x10-3 mol) of ethyl 2-(2-(p-tolyldiazenyl)phenylamino)acetate in 25 mL of ethanol
was placed in a 100 ml round-bottomed flask mounted on a magnetic stirrer and the
temperature was maintained at 35oC. 5 mL 1.4(M) KOH solution was added and stirring was
continued. The reaction was quenched after 1h by addition of 50 ml of water. Unreacted ethyl
2-(2-(p-tolyldiazenyl)phenylamino)acetate was removed by ether extraction (225mL) and
the aqueous part was acidified with 2(N) hydrochloric acid to bring the pH near 6. The H2L
ligand precipitated on standing and collected by filtration, dried under vacuum and
recrystallised from ethanol. Yield: 0.75g (83%) C15H15N3O2 (269): calcd: C 66.90, H 5.16, N
15.60; found: C 66.85, H 5.65, N 15.65. Melting point: 1030C. IR (KBr) ν = 1470 (N=N),
1721(C=O). 1H NMR (400MHz, DMSO d6): δ= 8.67 (s, 1H), 7.83 (d, 2H, J= 8.4), 7.71 (d,
1H, J= 7.2), 7.38 (d, 2H, J=8), 7.32-7.28 (m, 1H), 6.77- 6.7 (m, 2H), 4.03 (s, 2H), 2.34 (s,
3H). 13C NMR (400MHz, DMSO d6): 150.65 (s,1C), 142.99 (s,1C), 140.26 (s, 1C), 135.88 (s,1C),
133.18 (s,1C), 130.25 (s,1C), 129.24 (s,1C), 122.17 (s,1C), 115.11 (s,1C), 114.33(s, 1C), 113.09
(s,1C), 70.17 (s, 1C), 21.39 (s, 1C). UV-Vis spectrum (CH2Cl2) λmax (є, M-1cm-1): 424 (9677),
323 (17460), 242 (15154).
4

2.3.Syntheses of Complexes
2.3.1. Synthesis of [(HL)PdCl] complex, 2
The H2L (100 mg, 0.37 mmol) ligand was taken in round bottom flask in 10 mL methanol
and acidified with 0.3 mL 2(N) aqueous solution of HCl with stirring. The 5 mL methanolic
solution of Na2PdCl4 (108 mg, 0.37 mmol) was added drop wise into the acidified solution of
H2L. The color of the solution changed from light orange to brown. The mixture was stirred
for 4h and kept standing for 24 hours. The crystalline product of [(HL)PdCl] was collected
and further recrystallised from acetonitrile-dichlomethane mixture to obtain the crystals of
pure product. Yield: 85 mg (56%). C15H13ClN3O2Pd, 0.5 CH2Cl2 (451): calcd. for C 41.27, H
3.10, N 9.32; found: C 41.20, H 3.05, N 9.25. Melting point: 2330C. IR (KBr) ν = 3405 (NH),
1432 (N=N), 1720(C=O). 1H NMR (400MHz, DMSO d6): δ = 7.88 (d, 1H, J= 8), 7.75 (d, 1H, J=
8), 7.64-7.57 (m, 2H), 7.39 (t, 1H, J= 7.6 ), 7.23 (t, 1H, J= 18), 7.04 (d, 1H, J=8), 6.62 (s, 1H), 4.31
13
(d, 2H), 2.19 (s, 3H). C NMR (400 MHz, DMSO d6): δ 165.39 (s,1C), 159.63 (s,1C), 151.70
(s,1C), 147.17 (s,1C), 143.53 (s, 1C), 136.17 (s,1C), 134.58 (s,1C), 130.03 (s,1C), 128.79 (s,1C),
128.30 (s,1C), 128.05 (s, 1C), 127.05 (s,1C), 117.81(s, 1C), 82.28 (s,1C), 22.48 (s, 1C). UV-Vis
spectrum (CH2Cl2) λmax (є, M-1cm-1): 506(4267), 406(7209), 365(9982), 249(12364),
230(14681).
2.4. Immobilization of [(HL)PdCl] on Merrifield resin, 3
The [(HL)PdCl] complex (0.25 g) was dissolved in DMF (10 mL) and refluxed with
Merrifield resin beads (0.5 g) for 10 h in presence of K2CO3. After that the resin was filtered
and washed with large quantities of H2O, methanol, ethanol, dichloromethane until the
filtrate was colorless. The very dark brown beads were obtained after dried.
2.5. General experimental procedure for Suzuki cross-coupling reaction using [(HL)PdCl] in
homogeneous media
5

A mixture of aryl halide (1.0 mmol), phenylboronic acid (1.5 mmol), K2CO3 (2.0 mmol),
THF (6.0 ml) and 0.5 mol% of Pd catalyst, [(HL)PdCl] was refluxed. To study the progress
of the reaction the reaction mixtures were collected at different time interval and examined
by TLC. At the end of the reaction, the solvent was evaporated and the residue was purified
by chromatography on silica gel. The product was analyzed by 1HNMR.
2.6. General experimental procedure for Suzuki cross-coupling reaction using
P~[(L)PdCl]in heterogeneous phase
A mixture of aryl halide (1.0 mmol), phenylboronic acid (1.5 mmol), K2CO3 (2.0 mmol),
THF (6.0 ml) and 2.26 mg of P~[(L)PdCl] catalyst was refluxed. To study the progress of the
reaction, the reaction mixtures were collected at different time interval and examined by
TLC. At the end of the reaction, the catalyst was separated by simple filtration. After
evaporation of the solvent the residue was purified by chromatography on silica gel. The
product was analyzed by 1HNMR spectroscopy.
2.7. X-ray structure determination of [(HL)PdCl]
Single Crystal of [(HL)PdCl]
was grown by slow evaporation of acetonitrile-
dichlomethane mixture at 298 K. Data were collected on a Bruker SMART CCD
diffractometer using Mo-Kα monochromator (λ=0.71073). Structure solutions were
performed using SHELXTL V 6.14 program package. [30]. Full matrix least square
refinements on F2 were performed using SHELXTL V 6.14 program package. [30]. All the
non-hydrogen atoms were refined anisotropically using full-matrix least squares method.
Hydrogen atoms were included for structure factor calculations after placing them at
calculated positions. Atomic coordinates and isotropic thermal parameters are of [(HL)PdCl]
are given in Table 1
6

Table 1. Crystal data collection and structure refinement parameter for [(HL)PdCl]
Chemical formula
Formula weight
Crystal system
space group
a/Å
(C15H12ClN3O2Pd),0.5CH2Cl2
451
monoclinic
P21/c(No. 14)
11.0247(17)
17.669(3)
18.167(3)
90
b/Å
c/Å
/deg
98.699(4)
90
/deg
/deg
0.71073
3498.1(10)
1784
 /Å
V /Å3
F(000)
Z
4
T/K
296
D/mg/m-3
 /mm-1
R1(all data)
wR2[I > 2(I)]
GOF
1.711
1.378
0.0363
0.0910
1.05
3. Results and Discussion
3.1. Synthesis of H2L and [(HL)PdCl]
The newly designed ligand system, H2L, 1, was synthesized in two steps, starting from 2-
(arylazo)aniline. In the first step ethyl-2-bromoacetate was treated with 2-(Arylazo)aniline in
presence of anhydrous K2CO3 to obtain the new compound ethyl 2-(2-(aryldiazenyl)
phenylamino) ethanoate, in excellent yield (Scheme 2). The desired ligand, H2L, 1, was
obtained, in the second step, by alkaline hydrolysis of ethyl 2-(2-(aryldiazenyl) phenylamino)
7

ethanoate followed by acidification (Scheme 2). The H2L ligand was characterized by
spectroscopic studies (see below).
Scheme 2
The orthopalladated complex, [(HL)PdCl], 2, was prepared by the reaction of
Na2PdCl4 with acidified methanolic solution of H2L ligand (Scheme 2). Crystalline crude
product was isolated upon standing the reactions mixture for 36 hours at 280C. The crystals of
pure complex were isolated by recrystallisation. Acetonitrile-dichlomethane mixed solvent
was used for recrystallisation.
3.2. Characterization
The 2-(2-(p-tolyldiazenyl)phenylamino)ethanoic acid, H2L, 1, ligand display characteristic
UV-Vis spectra. The transition in the visible region near 425 nm for H2L was assigned for n
→ π* transition [29,31,32]. The electronic spectrum of [(HL)PdCl], 2 was distinctly different
from the corresponding ligand (Figure 1). The lowest energy absorption bands for
[(HL)PdCl] was observed near 505 nm. Relevant data are collected in experimental section.
8

Figure 1. UV-Vis spectra of H2L (▬, 1.75x10-5m) and [(HL)PdCl] (▬, 1.2x10-5m) in
dichloromethane.
The IR spectra of all new compounds were recorded using KBr pellet. The 2-(2-(p-
tolyldiazenyl) phenylamino) ethanoic acid, H2L ligand displayed a single band near 1470 cm-
1
for νN=N which shifted to 1432 cm-1 in [(HL)PdCl] indicating metal coordination to the azo
nitrogen. The characteristic νC=O and νC-OH of carboxylic group for H2L appeared at 1720
cm-1 and 1250 cm-1 respectively, did not disappear or shift in considerable extent for [(HL)-
PdCl] (1720 cm-1 and 1240 cm-1) signifying no interaction with the metal centre. Although the
νNH of H2L did not appear distinctly due to broad overlapping band of νOH of carboxyl group
but the νNH of the complex[(HL)PdCl] appeared distinctly at 3405 cm-1 [32].
The H2L, 1, ligand, atom numbering scheme is shown in Figure 2, displayed a well
1
resolved H-NMR spectrum. The N-H protons appeared at δ 8.67 for one equivalent proton
[32]. The aromatic proton resonances were observed within δ 6.72 to δ 7.83. The methylene
proton of C(14) appeared as doublet (due to coupling with N-H proton) at δ 4.03. The two
doublets, at δ 7.38 and δ 7.83, each of two equivalent protons for C(3);C(5) and C(2);C(6) of
1
H2L were recognized in the H-NMR spectra. The two doublets for C(9) and C(12) protons
9

appeared at δ 7.71 and δ 6.73 whereas two triplets for C(10) and C(11) protons were observed
at δ 7.28 and δ 6.75.
Figure 2: Structural formula of H2L
1
The [(HL)PdCl] complex i.e. the palladium complex of H2L exhibited well resolved H-
NMR spectrum. The methylene proton of C(14) appeared as doublet at δ 4.25 and the –NH-
proton appeared as a broad band at δ 6.42 indicating coordination of amino nitrogen without
dissociation of amino proton of the ligand [29]. The [(HL)PdCl] complex displayed a singlet
1
at δ 7.23 assigned for C(3). In addition to that the of the H-NMR spectrum exhibited three
doublets (δ 7.88, 7.75 and 7.04) for one equivalent proton each, a triplet (at δ 7.39) for one
equivalent proton and a quintet at (7.61) for two equivalent protons. The quintet has been
attributed to a doublet and a triplet. Thus the pattern and the proton count is consistent with
that of C(4), C(5), C(9), C(10), C(11), C(12) protons. The methyl proton of C(13) was
observed at δ 2.19. The molecular structure of [(HL)PdCl] was confirmed by x-ray studies
13
(see below). The C NMR spectra of the ligand H2L and complex [(HL)PdCl] displayed
thirteen and fifteen aromatic carbon resonances in the range δ 150.65 -21.39 and δ 165.39 –
22.48 respectively, consistent with the structural compositions of ligand H2L and complex
13
[(HL)PdCl]. 1H and C NMR data are given in Section 2. However, the prton resonance for
carboxyl group could not be obtained after repetitive experiments, may be due to
contaminated water in the DMSO-d6 solvent [33]. The broad signal of very high intensity
near δ 3.5 indicated the water contamination.
10

3.3. X-ray structure
The x-ray structure of [(HL)PdCl] complex, 2 was determined for unequivocal
characterization. The asymmetric unit consists of two [(HL)PdCl] complexes and one solvent
(dichloromethane) molecule. The bond parameters of two palladium complexes of
asymmetric unit are very close to infer that those are same. The perspective view of the
molecule has been shown in Figure 3. Selected bond distances and angles are collected in
Table 2.
Figure 3. Crystal structure of [(HL)PdCl] (2). Hydrogen atoms and solvent molecule are
omitted for clarity
Table 2. Selected Bond Distances (Å) and Angles (deg) for Compound [(HL)PdCl]
Bond Distances
Pd1-Cl1
Pd1-N1
Pd1-N2
Pd1-C12
N1-C1
N1-C13
N2-N3
N2-C2
2.329(3)
2.191(7)
1.937(7)
1.960(9)
1.456(12)
1.476(12)
1.275(10)
1.410(11)
N3-C7
C1-C2
C7-C8
C7-C12
C13-C14
O1-C14
O2-C14
1.398(12)
1.393(15)
1.379(15)
1.415(14)
1.508(14)
1.183(14)
1.315(13)
Bond Angles
N2-C2-C3
Cl1-Pd1-N1
99.3(2)
122.4(9)
11

Cl1-Pd1-N2
Cl1-Pd1-C12
N1-Pd1-N2
N1-Pd1-C12
N2-Pd1-C12
N1-C1-C6
177.6(2)
100.0(3)
81.3(3)
160.2(3)
79.3(3)
N2-C2-C1
N3-C7-C12
N3-C7-C8
Pd1-C12-C7
Pd1-C12-C11
115.7(8)
117.0(9)
121.1(9)
111.4(6)
132.9(7)
123.7(9)
The molecular structure confirmed orthopalladation and tridentate (C,N,N) binding mode of
monoanionic ligand (HL)-. In addition, a chloride ligand satisfied the tetra coordination about
palladium (II) centre and the geometry of the coordination sphere was distorted square planar.
Further, the x-ray structure confirmed the presence of uncoordinated free dangling carboxyl
group. The Pd-C and Pd-Cl distances are within the normal range whereas Pd-N1 distance
(2.191 Å) is longer than the Pd-N2 distance (1.937 Å) as a result of stronger trans effect of
aryl carbon atom ( C(12)) [29]. The molecules of [(HL)PdCl] complex form infinite array of
hydrogen bonded tetrameric units via hydrogen bonded carboxylic acid function. In each unit
of the array, the tetramers are held together through N…Cl…O hydrogen bonds [34,35]. A
part of the infinite array is shown in Figure 4 where the tetrameric unit has been shown in the
box.
Figure 4. The hydrogen bonded (ـ ـ ـ) array of [(HL)PdCl] in the crystal
3.4. Homogeneous catalysis
The catalytic activity of [(HL)PdCl] toward C-C coupling reactions in homogeneous media
was necessary to be examined before immobilization on polymer support. Therefore, this
12

complex was used as catalyst for Suzuki coupling reactions in homogeneous media i.e. in
THF (Scheme 3) under usual atmospheric condition.
Scheme 3
The complex exhibited fairly good efficacy as catalyst for Suzuki coupling reactions.
The isolated yields, reaction time and amount of catalyst used are given in Table 3.
3.5. Immobilization of [(HL)PdCl] in Merrifield resin and characterization
The chemical composition of Merrifield resin bead is chloromethylated polystyrene,
formulated as
. Although, tethering of carboxyl group with
[ CH2-CH(C6H4-CH2Cl) ]
n
the Merrifield Resin is well known but scarcely utilized for the immobilization of ligands or
complexes to prepare heterogeneous catalysts [13, 37-41]. Binding of carboxylic acid
function of the amino acid on the resin bead during solid phase peptide synthesis encouraged
us to utilize the free carboxylic acid function of [(HL)PdCl] for anchoring with the Merrifield
resin by forming C-O bond formation. Thus, the [(HL)PdCl], 2, complex was refluxed with
Merrifield resin beads in DMF solvent in presence of K2CO3 to obtain the immobilised
catalyst P~[(L)PdCl], 3 (Scheme 4). Absence of sharp band at 1240 cm-1 of free [(HL)PdCl]
for νCOO- and 1264 cm-1 for νC-Cl of Merrifield resin
Scheme 4
13

in the P~[(L)PdCl], 3 indicated the formation P~[(L)PdCl]. The SEM images and EDX
spectrum of P~[(L)PdCl] have been shown in Figure 4 and Figure 5. The morphological
changes are visible in the SEM image and the EDX shows the presence of palladium which
are consistent with the formation of P~[(L)PdCl], 3.
Figure 4. SEM images of Merrifield resin (A) and P~[(L)PdCl] complex (B)
Figure 5. EDX spectra of P~[(L)PdCl] complex
3.6. Heterogeneous catalysis
Keeping in view the application and interest on palladium based heterogeneous catalysts in
academia and industry, there is a need to design and develop active, re-usable and easily
recoverable chemically supported heterogeneous palladium catalysts [13,38,42-46]. The P~
[(L)PdCl] has been used as catalyst for Suzuki cross coupling reactions and it was found that
this heterogeneous catalyst was efficient for such catalysis (results are collected in Table 3).
14

Although the inclusion of [(HL)PdCl] in Merrifield resin could be detected by EDX but the
loading of catalyst could not be determined quantitatively. For each reaction in heterogeneous
phase weighted amount of P~ [(L)PdCl] beads were added as catalyst.
Table 3. Assessment of catalytic activity in Suzuki cross coupling reaction catalysed by P~
[(L)PdCl], 3 and [(HL)PdCl], 2
Further, the P~ [(L)PdCl] species could be reused as catalyst (up to three times were
checked) without much difference in isolated yields. However, the higher yield than the
homogenous process is attributed to ease of isolation of products.
4. Conclusions
New azo ligand with free carboxylic acid function has been synthesized and form that the
new orthometallated palladium complex has been prepared. The newly synthesized
orthopalladated complex contains uncoordinated pendant carboxylic acid function. The new
15

complex was efficient catalyst for Suzuki C-C coupling reactions in homogeneous media.
The free pendant carboxylic acid function of palladium complex has been utilized to
immobilize the palladium complex on Merrifield resin. The immobilized catalyst exhibited
catalytic efficacy toward Suzuki C-C coupling reactions keeping it in heterogeneous media.
Acknowledgments
Author P.P. is thankful to the DST (New Delhi) for funding under DST-WOS-A project
(No.SR/WOS-A/CS-4/2017). The necessary laboratory and infrastructural facility are
provided by the Dept. of Chemistry, University of Kalyani. The support of DST under FIST
and UGC -SAP program to the Department of Chemistry, and PURSE to the University of
Kalyani is acknowledged.
Appendix A. Supplementary materials
CCDC 1012256 for 2 contains the supplementary crystallographic data. Figures S1-S13
13
represents the UV-Vis; IR, 1H NMR and C NMR spectra of ligand and complexes. These
data can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or
from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ,
UK; fax: +44 1223 336 033; or e-mail: deposit@ccdc.cam.ac.uk. Supplementary data
associated with this article can be found, in the online version, at http://..
References
[1] M. Carreira, R. Calvo-Sanjuán, M. Sanaú, I. Marzo, M. Contel, Organometallics 31
(2012) 5772–5781.
[2] U. Christmann, R. Vilar, Angew. Chem. Int. Ed., 44 (2005) 366 –374.
[3] M. Albrecht, B. M. Kocks, A. L. Spek, G. van Koten, J. Mol. Catal. A: Chem., 276 (2007)
219–225.
[4] J. Vicente, A. Arcas, D. Bautista, Organometallics 16 (1997) 2127–2138.
16

[5] F. McLachlan, C. J. Mathews, P. J. Smith, T. Elton, Organometallics 22 (2003) 5350–
5357.
[6] J. Vicente, I. Saura-Llamas, C. Grünwald, C. Alcaraz, P. G. Jones, D. Bautista
Organometallics 21 (2002) 3587–3595.
[7] J. Luan, L. Zhang, Z. Hu, Molecules 16 (2011) 4191-4230.
[8] O. V. Gusev, T. A. Peganova, A. M. Kalsin, N. V. Vologdin, P. V. Petrovskii, K. A.
Lyssenko, A. V. Tsvetkov, I. P. Beletskaya, Organometallics 25 (2006) 2750–2760.
[9] M. Islam, P. Mondal, K. Tuhina; A. Singha Roy, S. Mondal, D. Hossain, Tetr. Lett., 51
(2010) 2067–2070.
[10] N. Selander, K. J. Szab’o, Chem. Rev. 111 (2011) 2048–2076.
[11] D. Wang, A. B. Weinstein, P. B. White, S. S. Stahl, Chem. Rev., 118 (2018) 2636−2679.
[12] T. W. Lyons, M. S. Sanford, Chem. Rev., 110 (2010) 1147–1169.
[13] J. He, M. Wasa, K. S. L. Chan, Q. Shao, J. Q. Yu, Chem. Rev. 117 (2017) 8754−8786.
[14] P. Pattanayak, J.L. Pratihar, D. Patra, C. -H. Lin. S. Chattopadhyay, Polyhedron
63 (2013) 133–138.
[15] J. L. Pratihar, P. Pattanayak, D. Patra, C. -H. Lin, S. Chattopadhyay, Polyhedron 33
(2012) 67–73.
[16] P. Pattanayak, J. L. Pratihar, D. Patra, P. Brandão, V. Felix, S. Chattopadhyay
Polyhedron 79 (2014) 43–51.
[17] D. Patra, C. -K. Lai, P. Brandão, V. Felix, S. Chattopadhyay, Inorg. Chim. Act., 429
(2015)122–131.
[18] U. Das, P. Pattanayak, D. Patra, C. -K. Lai, P. Brandão, V. Felix, S. Chattopadhyay,
Polyhedron 110 (2016)165–171.
[19] V. Lapinte, V´. Montembault, A. Houdayer, L. Fontaine, J. Mol. Catal. A: Chem., 276
(2007) 219–225.
[20] D. A. Annis and E. N. Jacobsen, J. Am. Chem. Soc., 121 (1999) 4147-4154.
17

[21] A. Bukowska, W. Bukowski, Reac & Func. Pol., 68 (2008) 657–670.
[22] S. M. Islam, P. Mondal, A. Singha Roy, S. Mondal, D. Hossain, Tetr. Lett., 51 (2010)
2067–2070.
[23] V. Pozsgay, Org. Lett., 1 (1999) 477-479.
[24] J. Gustavo Avila-Za rraga, R. Martı´nez, Synth. Comun., 31 (2001) 2177–2183.
[25] J. Alvim Jr., R.L. A. Diasa, M. S. Castilhob, G. Olivab, A. G. Corrêa, J. Braz. Chem.
Soc.,16 (2005) 763-773.
[26] G. Lamoureux, C. Agüero. Arkivoc 1 (2009) 251-264.
[27] T. Ooi, H. Sugimoto, K. Doda, K. Maruoka, Tetr. Lett., 429 (2001)245–9248.
[28] L. Brinchi, R. Germani, G. Savelli, Tetr. Lett., 44 (2003) 2027–2029.
[29] N. Maiti, S. Pal, S. Chattopadhyay, Inorg. Chem., 40 (2001) 2204-2005.
[30] 36 G. M. Sheldrick, SHELXTL, v. 6.14, Bruker AXS Inc., Madison, WI, 2003.
[31] N. Maiti, B.K. Dirghangi, S. Chattopadhyay, Polyhedron 22 (2003) 3109-3113.
[32] J. L. Pratihar, N. Maiti, P. Pattanayak, S. Chattopadhyay, Polyhedron 24 (2005) 1953–
1960.
[33] P. Charisiadis, V. G. Kontogianni, C. G. Tsiafoulis, A. G. Tzakos, M. Siskos, I. P.
Gerothanassis, Molecules 19 (2014) 13643-13682.
[34] U. Turi, J. J. Dannenberg, J. Phys. Chem., 97 (1993) 12197-12204.
[35] A. M. Beatty. Coord. Chem. Rev., 246 (2003) 131–143.
[36] B. R. Bhogala, S. Basavoju, A. Nangia, Cryst. Eng. Comm., 7 (2005) 551–562.
[37] Z. Qin, M.C. Jennings, R. J. Puddephatt, Inorg. Chem., 41 (2002) 5174-5186.
[38] S. A. Patel, K. N. Patel, S. Sinha, B.V. Kamath, A.V. Bedekar, J. Mol. Catal. A: Chem.,
332 (2010) 70–75.
[39] B. Yan, J. B. Fell, G. Kumaravel, J. Org. Chem., 61 (1996) 7467-7472.
[40] Y. Liu, J. C. Vederas, J. Org. Chem., 61 (1996) 7856-7859.
18

[41] V. Lapinte, V. Montembault, A. Houdayer, L. Fontaine, J. Mol. Catal. A: Chem., 276
(2007) 219–225.
[42] R. B. Merrifield, J. Am. Chem. Soc., 8 (1963) 2149.
[43] W. Gil, K. Boczon, A. M. Trzeciaka, J. J. Ziołkowski, E. G.-Verdugo, S. V. Luis, V.
Sans. J. Mol. Catal. A: Chem., 309 (2009) 131–136.
[44] N. T. S. Phan, H. V. Le, J. Mol. Catal A: Chem., 334 (2011)130–138.
[45] P. Karthikeyan, A. Vanitha, P. Radhika, K.Suresh, A. Sugumaran, Tetr. Lett., 54 (2013)
7193–7197.
[46] N.T. S. Phan, D. H. Browna, P. Styring, Tetr. Lett., 45 (2004) 7915–7919.
19

Design and synthesis of immobilised orthopalladated catalyst
for C-C coupling
Poulami Pattanayaka, Sankar Prasad Paruaa and Surajit Chattopadhyaya*
a Department of Chemistry, University of Kalyani, Kalyani 741235
OH
Cl
B
X
+
R
Pd
N
O
R
OH
N
N
O
H
Merrifield
Resin
Heterogeneous
Suzuki
Homogeneous
Suzuki
Merrifield
Resin
OH
OH
R
B
X
+
R
20

Graphical Abstract Synopsis
Design and synthesis of immobilised orthopalladated catalyst
for C-C coupling
Poulami Pattanayaka, Sankar Prasad Paruaa and Surajit Chattopadhyaya*
a Department of Chemistry, University of Kalyani, Kalyani 741235
OH
Cl
B
X
+
R
Pd
N
O
R
OH
N
N
O
H
Merrifield
Resin
Heterogeneous
Suzuki
Homogeneous
Suzuki
Merrifield
Resin
OH
OH
R
B
X
+
R
21

New orthopalladated complex was synthesized and characterized unequivocally prior to
immobilization on polymer support through the free carboxylic acid function. The newly synthesized
palladium complex was active as catalyst for C-C coupling reactions in homogeneous media. Thus it
was anchored on Merrifield resin. This polymer supported catalyst exhibited good efficacy as
catalyst toward C-C coupling reactions.
22