Spectral and crystallography studies of new palladacycle complexes with P,C- and C,C-donor ligands; Application of (OAL16) to optimizing the yield of Mizoroki-Heck reaction

Article abstract of DOI:10.1002/aoc.4882

The new symmetrical diphosphonium salt [Ph₂P(CH₂)₂PPh₂(CH₂C(O)C₆H₄Br)₂] Br₂ (S) was synthesized in the reaction of 1,2-bis (diphenylphosphino) ethane (dppe) and related ketone. Further treatment with NEt₃ gave the symmetrical α-keto stabilized diphosphine ylide [Ph₂P(CH₂)₂PPh₂(CHC(O)C₆H₄Br)₂] (Y¹). The unsymmetrical α-keto stabilized diphosphine ylide [Ph₂P(CH₂)₂PPh₂(CHC(O)C₆H₄Br)] (Y²) was synthesized in the reaction of diphosphine in 1:1 ratio with 2.3′-dibromoacetophenone, then treatment with NEt_3. The reaction of dibromo (1,5-cyclooctadiene)palladium (II), [PdBr₂(COD)] with this ligand (Y¹) in equimolar ratio gave the new C,C-chelated [PdBr₂(Ph₂P(CH₂)₂PPh₂(C(H)C(O)C₆H₄Br)₂)] (1) and with unsymmetrical phosphorus ylide [Ph₂P(CH₂)₂PPh₂C(H)C(O)C₆H₄Br] (Y²) gave the new P, C-chelated palladacycle complex [PdBr₂(Ph₂P(CH₂)₂PPh₂C(H)C(O)Br)] (2). These compounds were characterized successfully by FT-IR, NMR (¹H, ¹³C and ³¹P) spectroscopic methods and the crystal structure of Y¹ and 2 were elucidated by single crystal X-ray diffraction. The results indicated that the complex 1 was C, C-chelated whereas complex 2 was P, C-chelated. These air/moisture stable complexes were employed as efficient catalysts for the Mizoroki-Heck cross-coupling reaction of several aryl chlorides, and the Taguchi method was used to optimize the yield of Mizoroki-Heck coupling. The optimum condition was found to be as followed: base; K₂CO₃, solvent; DMF and loading of catalyst; 0.005?mmol.

Full text of DOI:10.1002/aoc.4882

Received: 28 September 2018
DOI: 10.1002/aoc.4882
Revised: 18 November 2018
Accepted: 1 February 2019
F U L L P A P E R
Spectral and crystallography studies of new palladacycle
complexes with P,C‐ and C,C‐donor ligands; Application of
(OAL16) to optimizing the yield of Mizoroki‐Heck reaction
Seyyed Javad Sabounchei1
Robert W. Gable2
| Khadijeh Badpa1 | Ali Hashemi1 | Faezeh Moniriyan1 |
1 Faculty of Chemistry, Bu‐Ali Sina
University, Hamedan 65174, Iran
2 School of Chemistry, University of
Melbourne, Victoria 3010, Australia
The new symmetrical diphosphonium salt [Ph2P(CH2)2PPh2(CH2C(O)
C6H4Br)2] Br2 (S) was synthesized in the reaction of 1,2‐bis
(diphenylphosphino) ethane (dppe) and related ketone. Further treatment with
NEt3 gave the symmetrical α‐keto stabilized diphosphine ylide
[Ph2P(CH2)2PPh2(CHC(O)C6H4Br)2] (Y1). The unsymmetrical α‐keto stabilized
diphosphine ylide [Ph2P(CH2)2PPh2(CHC(O)C6H4Br)] (Y2) was synthesized in
the reaction of diphosphine in 1:1 ratio with 2.3′‐dibromoacetophenone, then
treatment with NEt3. The reaction of dibromo (1,5‐cyclooctadiene)palladium
(II), [PdBr2(COD)] with this ligand (Y1) in equimolar ratio gave the new C,C‐
chelated [PdBr2(Ph2P(CH2)2PPh2(C(H)C(O)C6H4Br)2)] (1) and with unsym-
metrical phosphorus ylide [Ph2P(CH2)2PPh2C(H)C(O)C6H4Br] (Y2) gave the
new P, C‐chelated palladacycle complex [PdBr2(Ph2P(CH2)2PPh2C(H)C(O)
Br)] (2). These compounds were characterized successfully by FT‐IR, NMR
(1H, 13C and 31P) spectroscopic methods and the crystal structure of Y1 and 2
were elucidated by single crystal X‐ray diffraction. The results indicated that
the complex 1 was C, C‐chelated whereas complex 2 was P, C‐chelated. These
air/moisture stable complexes were employed as efficient catalysts for the
Mizoroki‐Heck cross‐coupling reaction of several aryl chlorides, and the
Taguchi method was used to optimize the yield of Mizoroki‐Heck coupling.
The optimum condition was found to be as followed: base; K2CO3, solvent;
DMF and loading of catalyst; 0.005 mmol.
Correspondence
Seyyed Javad Sabounchei, Faculty of
Chemistry, Bu‐Ali Sina University,
Hamedan, 65174, Iran.
Email: jsabounchei@yahoo.co.uk
KEYWORDS
Pd ‐cyclic complexes, phosphorus ylide, symmetrical phosphorus ylide, Taguchi method,
unsymmetrical X‐ray
1 | INTRODUCTION
Furthermore, they are valuable key intermediates in
metal‐mediated organic synthesis.[4,5] Also, the basicity
Stabilized phosphorus ylides derived from diphosphines
are important reagents in organic chemistry, and have
shown more useful application in organometallic chemis-
try due to their ambidentate character as ligands.[1–3]
or steric properties of the two phosphorus atoms in these
phosphorus ylides can be different and may be used to get
different coordination modes.[6] The coordination chem-
istry of α‐keto stabilized phosphorus ylides is interesting
Appl Organometal Chem. 2019;e4882.
wileyonlinelibrary.com/journal/aoc
© 2019 John Wiley & Sons, Ltd.
1 of 14
https://doi.org/10.1002/aoc.4882

2 of 14
SABOUNCHEI ET AL.
to chemists, because of the different bonding modes upon
coordination of ylides to metal,[7–10] a) C‐coordinated
(through the Cα atom), b) O‐ coordinated (through the
O atom of the carbonyl), c) P‐ coordinated (through the
P atom of the phosphine group), and d) even situations
in which the same ylide shows a combination of bonding
modes (Scheme 1).
purification. The [PdBr2(COD)] complex was prepared
according to previously published procedures.[21] Phos-
phorus ylide Y2 was synthesized and characterized with
previously published method.[3] Toluene, n‐hexane and
chloroform were used as reagent grade and dried over
1
Na/Benzophenone and CaCl2 subsequently. The H, 13C
and 31P NMR spectra were recorded on 250 MHz Bruker
and 90 MHz Jeol spectrometers with CDCl3 as solvent at
25 °C. IR spectra were recorded with KBr pellets using a
Shimadzu 435‐U04 spectrophotometer in the region of
Additionally, Pd (II) complexes bearing phosphine
groups have been extensively applied as efficient catalysts
in some cross‐coupling reactions,[11–17] specifically, the
Mizoroki‐Heck reaction. The Mizoroki‐Heck reaction,
has emerged as the most important and reliable method
for construction of functionalized olefins, and it can be
catalyzed with the Pd (II) complexes of such phosphorus
ylides.[18,19] Palladium complexes (1 and 2) were
employed as homogeneous catalysts in C‐C coupling
reactions. There are many controlling factors such as
base, solvent, temperature, time, catalyst (mol%), etc.
The appropriate selection of conditions for cross coupling
reactions can be done with the Taguchi Method. The
Taguchi method is generally used for process optimiza-
tion, because it can noticeably reduce the time and costs
associated with achieving optimum conditions.[20] There-
fore, some of the possible analytical methods like
Taguchi, analysis of variance (ANOVA), and signal‐to‐
noise (S/N) ratio were used in this work.
4000–400 cm−1
.
2.2 | Synthesis of diphosphonium salt
2.2.1 | General procedure
A solution consisting of 1, 2‐bis (diphenylphosphino) eth-
ane (0.25 mmol) and ketone (0.5 mmol) in acetone (5 ml)
was stirred at room temperature for 24 hr. The resulting
solution was filtered off and concentrated to ca. 3 ml
under reduced pressure and then treated with diethyl
ether to precipitate the diphosphonium salt.
2.2.2 | Data for [Ph2P(CH2)2PPh2(CH2C(O)
C6H4Br)2] Br2 (S)
In this work we have focused our attention to the syn-
thesis, spectroscopic (IR and NMR) and X‐ray structural
characterization of these new complexes of phosphorus
ylide. Furthermore Pd (II) complex catalyzed Mizoroki‐
Heck coupling reaction of various aryl chlorides and ole-
fins is reported.
Yield: 0.051 g (85%), M.p. 212 °C. IR (KBr disk) ν (cm−1):
1669(C=O). H NMR (CDCl3) δH (ppm): 4.04 (br, 4H,
CH2), 6.06 (br, 2H, PCH2CO); 7.58–8.28 (m, 28H, Ph).
31P NMR (CDCl3) δP (ppm): 26.76 (s, PCH2). 13C NMR
(CDCl3) δC (ppm): 15.29(m, CH2); 32.9 (m, PCH2);
116.95–137.9 (m, Ph); 191.9 (s, CO).
1
2 | EXPERIMENTAL
2.3 | Synthesis of diphosphine ylide
2.3.1 | General procedure
2.1 | Materials and methods
All synthetic reactions were carried out under dry nitro-
gen using standard Schlenk techniques. 2‐bromo‐3′‐
bromoacetophenone, (1,5‐cyclooctadiene) (COD) and
1,2‐bis (diphenylphosphino) ethane dppe were purchased
from commercial sources and used without further
The diphosphonium salt was further treated with triethyl
amine (0.5 ml) in dry toluene. The triethylammonium
bromide was filtered off. Concentration of the toluene
layer to ca. 3 ml and subsequent addition of petroleum
ether (20 ml) resulted in the precipitation of diphosphine
ylide.
2.3.2 | Data for [Ph2P(CH2)2PPh2(CHC(O)
C6H4Br)2] (Y1)
Yield: 0.051 g (85%), M.p. 212 °C. Anal. Calcd. for
C42H34Br2O2P2 (%): C, 63.66; H, 4.32. Found: C, 63.75;
1
H, 4.43. IR (KBr disk) ν (cm−1): 1568(C=O). H NMR
SCHEME 1 The possible coordination modes of phosphine
ligands
(CDCl3) δH (ppm): 3.33 (s, 4H, CH2); 4.24 (m, 1H,

SABOUNCHEI ET AL.
3 of 14
PCH); 7.24–8.16 (m, 28H, Ph).31P NMR (CDCl3) δP (ppm):
15.26 (s). 13C NMR (CDCl3) δC (ppm): 18.81(m, CH2);
47.9(m, PCH); 122.33–143.17 (m, Ph); 183.46 (s, CO).
hydrogen atoms were refined with anisotropic displace-
ment parameters, using all data. Hydrogen atoms were
located in ideal positions. For 2 there were two indepen-
dent molecules in the asymmetric unit, together with a
molecule of dichloromethane and a partially occupied
molecule of solvent water; the occupancy factor refined
to 0.368(13) (See supporting information).
2.4 | Synthesis of Pd complexes
2.4.1 | General procedure
To
a
dichloromethane solution of [PdBr2(COD)]
2.6 | Typical procedure for the
Mizoroki‐heck reaction
(0.5 mmol, 5 ml), a solution of ylide (0.5 mmol) (5 ml,
CH2Cl2) was added. The resulting solution was stirred
for 2 hr at room temperature and then concentrated to
a ca. 2 ml under reduced pressure and treated with n‐
hexane (5 ml) to afford a yellow precipitate of the Pd
complexes of the desired diphosphine ylide.
2.6.1 | General procedure
Palladium (II) complex 2 (0.005 mmol), olefin (0.75 mmol),
aryl chloride (0.5 mmol), K2CO3 (1 mmol) and DMF (2 ml)
were added to a small tube and the mixture was heated to
130 °C for 6 hr in the presence of air. The reactions were
monitored by thin‐layer chromatography (TLC). After
being cooled to ambient temperature, the mixture was
extracted with n‐hexane: EtOAc (8:2) filtered and purified
by recrystallization from ethanol and water or purified by
silica gel column chromatography to give a crude product
which was analyzed by 1H and 13C NMR spectroscopy.
2.4.2 | Data for [PdBr2(Ph2P
(CH2)2PPh2(C(H)C(O)C6H4‐m‐Br)2)] (1)
Yield: 0.054 g (95%), M.p. 205 °C. IR (KBr disk) ν (cm−1):
1
1634 (C=O). H NMR (CDCl3) δH (ppm): 3.7 (m, 4H,
PCH2); 6.5 (br, 1H, PCH); 7–8.6 (m, 28H, Ph). 31P NMR
2
(CDCl3) δP (ppm): 29.57 (d, PPh2, JP‐P = 4 Hz); 32.9 (d,
PCH, JP‐P = 4 Hz). 13C NMR (CDCl3) δC (ppm):
2
38.72(s, CH2); 50.81 (s, PCH); 118.78–140.87 (m, Ph);
197.99(s, CO).
2.6.2 | Data for p‐CH3‐Ph‐CH=CHCOOEt
(5a)
1H NMR (CDCl3) δH (ppm): δ = 7.66 (d, 1H, CHCO,
J = 16.21 Hz), 7.13–7.47 (m, 4H, Ph), 6.38 (d, 1H, CHPh
J = 16.03 Hz), 4.26 (q, 2H, CH2, J = 7.07 Hz), 2.37 (s,
3H, CH3), 1.33 (t, 3H, CH3 J = 6.98 Hz). 13C NMR
(ppm): δ = 167.2 (s, CO), 144.5, 140.6, 131.7, 129.6,
128.0, 117.1, 60.4 (s, CH2), 21.4 (s, CH3), 14.3 (s, CH3).
2.4.3 | Data for [PdBr2(Ph2P
(CH2)2PPh2C(H)C(O)C6H4‐m‐Br)] (2)
Yield: 0.051 g (85%), M.p. 212 °C. Anal. Calcd. for
C34H29Br3OP2Pd (%): C, 52.15; H, 5.53. Found: C, 52.23;
H, 5.64. IR (KBr disk) ν (cm−1): 1622(C=O). H NMR
1
(CDCl3) δH (ppm): 4.8 (m, 4H, PCH2P); 5.8 (s, H, PCH);
7–8.3 (m, 24H, Ph).31P NMR (CDCl3) δP (ppm): 22.54 (d,
2.6.3 | Data for p‐CHO‐Ph‐CH=CHCOOEt
(5b)
2
2
PPh2, JP‐P
=
22.22 Hz); 30.66 (d, PCH, JP‐
= 22.22 Hz). 13C NMR (CDCl3) δC (ppm): 27.94(s,
P
1H NMR (CDCl3) δH (ppm): 9.95 (s, 1H, CHCO), 7.35–7.88
(m, 5H, Ph), 6.47 (d, 1H, CHPh, J = 16.21 Hz), 4.23 (q, 2H,
CH2, J = 7.25 Hz), 1.28 (t, 3H, CH3, J = 6.98 Hz). 13C NMR
(ppm): δ = 190.4 (s, CO), 165.3 (s, CO), 141.7, 139.0, 136.0,
129.1, 127.4, 120.3, 59.7 (s, CH2), 13.2 (s, CH3).
CH2); 49 (s, PCH); 121.81–140.32 (m, Ph); 194.25(s, CO).
2.5 | Crystallography
Single crystals of Y1 and 2 were crystallized by slow evap-
oration from dichloromethane solution. A suitable crystal
was selected and mounted on a Rigaku Oxford Diffrac-
tion SuperNova, Dual, Cu at zero, Atlas diffractometer.
The crystal was kept at 130.00(10) K during data collec-
tion. Using Olex2,[22] the structure was solved with the
ShelXT[23] structure solution program using Intrinsic
Phasing and refined with the ShelXL[24] refinement pack-
age using Least Squares minimization. Gaussian absorp-
tion corrections were applied to the data. All non‐
2.6.4 | Data for p‐NO2‐Ph‐CH=CHCOOEt
(5c)
1H NMR (CDCl3) δH (ppm): 7.18–8.22 (m, 5H, Ph), 6.47
(d, 1H, CHCO, J = 16.03 Hz), 4.22 (q, 2H, CH2,
J = 7.07 Hz), 1.28 (t, 3H, CH3, J = 7.34 Hz). 13C NMR
(ppm): δ = 166.7 (s, CO), 139.5, 137.0, 130.8, 128.3,
128.0, 117.0, 60.4 (s, CH2), 14.3 (s, CH3).

4 of 14
SABOUNCHEI ET AL.
2.6.5 | Data for Ph‐CH=CHCOOEt (5d)
1H NMR (CDCl3) δH (ppm):7.56 (d, 1H, CHCO,
J = 16.10 Hz), 7.24–7.65 (m, 5H, Ph), 6.30 (d, 1H, CHPh,
J = 16.03 Hz), 4.13 (q, 2H, CH2, J = 6.98 Hz), 1.20 (t, 3H,
CH3, J = 6.98 Hz). 13C NMR (ppm): δ = 165.8 (s, CO),
143.4, 133.3, 129.1, 127.8, 126.9, 117.1, 59.3 (s, CH2),
13.2 (s, CH3).
2.6.6 | Data for p‐CH3OC‐Ph‐
CH=CHCOOEt (5e)
1H NMR (CDCl3) δH (ppm):7.77 (d, 1H, CHCO,
J = 15.68 Hz), 6.99–7.37 (m, 4H, ph), 6.22 (d, 1H, CHPh,
J = 15.77 Hz), 4.23 (q, 2H, CH2, J = 7.07 Hz), 2.56 (s, 3H,
CH3), 1.31 (t, 3H, CH3O, J = 7.16 Hz). 13C NMR (ppm):
δ = 197.2 (s, CO), 166.7 (s, CO), 138.5, 137.0, 130.8,
128.3, 128.1, 117.0, 60.6 (s, CH2), 14.2 (s, CH3).
SCHEME 2 Synthesis of palladacycle complexes 1, 2
3 | RESULTS AND DISCUSSION
3.1 | Synthesis
TABLE 1 Spectroscopic data for compounds S, Y1, Y2, 1 and 2
IR; ν 1H NMR; δ 13C NMR; 31P NMR; δ
Diphosphine Ph2P(CH2)2PPh2 reacts in 1:2 ratio with
2.3′‐dibromoacetophenone
forming
the
new
(CO) (PCHor
δ (CO)
(PCH) and
(PPh2) ppm
Compound cm−1 PCH2) ppm ppm
diphosphonium salt S in 90–95% yields. Further treat-
ment of this salt with triethyl amine leads to elimination
of HBr, giving the new symmetrical diphosphine ylide Y1
in 80–85% yields. The reaction of [PdBr2(COD)] with this
ligand (Y1) in equimolar ratio gave the new C,C‐chelated
[PdBr2(Ph2P(CH2)2PPh2(C(H)C(O)C6H4Br)2)] (1) and
with the unsymmetrical phosphorus ylide [Ph2P(CH2)2
PPh2C(H)C(O)C6H4Br] (Y2) gave the P, C‐chelated
palladacycle complex [PdBr2(Ph2P(CH2)2PPh2C(H)C(O)
Br)] (2) (Scheme 2). All complexes are moderately soluble
in dichloromethane and insoluble in non‐polar solvents,
such as n‐hexane.
S
1669 6.06
1568 4.24
1571 4.08
1634 6.33
1622 6.41
191.9
26.76
Y1
Y2
1
183.46
183.36
197.99
194.25
15.26
14.45, −15.63
32.9, 29.57
30.66, 22.54
2
a significant increase in the ν CO frequency. IR spectra
of complexes 1 and 2 show a significantly frequency shift
of ν (CO) than those of the related phosphorus ylides Y1
and Y2. These observations are in agreement with the
chelating of ylide Y1 through two Cα atoms and ylide
Y2 through the P and Cα atoms. Presence of ν CO bands
around 1634–1622 cm−1 in the IR spectra of these com-
plexes indicates that products (C, C and P, C‐chelated
complexes) were formed.
3.2 | Characterization
1
The structure of products was characterized by IR, H,
13C and 31P NMR spectroscopic methods; Table 1 shows
important details.
3.2.1 | Infra‐red spectra
3.2.2 | NMR
The ν (CO) in the IR spectra of phosphorus ylide Y1 was
observed in lower frequencies than those of the related
phosphonium salt S, suggesting some lowering of elec-
tron density in the C=O bond. As noted in the litera-
ture,[25] coordination of ylide through the carbon, causes
The 31P NMR spectra of phosphonium salt S shows a sin-
glet around 26.76 ppm, due to the PPh2 groups, which
indicates that the two phosphorus atoms are equivalent,
this peak shifted to around 15.26 ppm in spectra of ylide

SABOUNCHEI ET AL.
5 of 14
Y1, and show upfield shift compared to that of parent
phosphonium salt, suggesting some electron density
increase in the P–C bond. The 31P chemical shift values
for complexes 1 and 2 appear to be shifted downfield with
respect to parent ylides Y1 and Y2, indicating that coordi-
nation of the ylide has occurred. Coordination of phos-
phorus ylides as C, C‐chelated and P, C‐chelated forms
can make a large chemical shift for both free (PPh2) and
bonded (PCH) phosphorus atoms. While, in P, P‐ coordi-
nated form only the signal of PPh2 moiety was shifted to
higher frequencies. The 31P NMR spectrum of the com-
plex 1 features two doublets around 29.57, 32.9 ppm,
shifted downfield compared with that of the phosphorus
ylide (around 15.26 ppm), due to the coordination of the
ylide to palladium through the carbon atoms (ylidic car-
bon).[26] The 31P NMR spectrum of complex 2 shows
two doublet peaks around δ = 22.54, 30.66 ppm which
are assigned to PPh2 and PCH, respectively.
has occurred through two Cα atoms and in complex 2 of
the ylide Y2 through P and Cα atoms.
In the 13C NMR spectra of complexes 1 and 2, most of
the expected resonances are visible and characteristic
peaks of carbonyl, methinic and methanediyl groups in
complexes 1 and 2 show downfield shift respect to the
parent ylide Y1 and Y2. Furthermore, strong deshielding
in resonance value was observed for the CH2 after com-
plexation (around 10 ppm), which is in agreement with
the C,C‐ coordination character of the ylide in complex
1. These observations also confirmed that coordination
of ylides Y2 has occurred through P and Cα atoms and
ylide Y1 has occurred through the two Cα atoms.
3.3 | Crystallography
Suitable single crystals of Y1 and 2 were grown by slow
evaporation from dichloromethane solution. The molecu-
lar structures of Y1 and 2 are shown in Figure 1 and
Figure 2, respectively. Relevant parameters concerning
data collection and refinement are given in Table 2.
Selected bond distances and angles for the unit cells of
Y1 and 2 are displayed in Table 3.
1
The H NMR spectra of the ylide Y1 shows an upfield
shift in the CH signals compared to those of the phospho-
nium salt S. These observations were related to the
increasing of the electron density in the P‐C bonds. The
1H NMR spectra of complexes 1 and 2 exhibit characteris-
tic shifts in the methinic proton signals. This is interest-
ing, because complexation of the ylides (Y1/Y2) to Pd
through free phosphorus atom did not significantly
change the chemical shift values of 1H NMR. While, coor-
dination through carbanion causes to shift of PCH peaks
to higher frequency around 6.33–6.41 ppm. The 1H chem-
ical shift values for these complexes appeared to be
shifted downfield with respect to the parent ylide, indicat-
ing also that the coordination of the ylide Y1 in complex 1
3.3.1 | Crystal structures of Y1
The molecule lies on a center of symmetry. The phospho-
rous atom is coplanar with the keto group, the dihedral
angle between these atoms and the aromatic ring is
21.08(9)° while the Br atom on the attached aromatic ring
is oriented away from the carbonyl oxygen, the Br1‐C5 …
FIGURE 1 ORTEP view of X‐ray
crystal structure Y1

6 of 14
SABOUNCHEI ET AL.
FIGURE 2 ORTEP view of X‐ray crystal structure of molecules 1 and 2
C2‐O1 torsion angle being −154.77(16)°. The structure has
(sp3)) bonds, 1.800 Å and 1.511 Å, respectively,[27] while
the C‐O bond length is significantly longer than the nor-
mal value of 1.210 Å. This has been attributed to the
ylidic resonance involving electron delocalization over
the P1‐C1–C2–O1 moiety.[12,27] One main difference
between the two structures, however, is that the dihedral
some
similarities
to
2,2′‐(ethane‐1,2‐diylbis
(diphenylphosphoranylylidene))bis(1‐(2,4‐
dichlorophenyl)ethanone),[12] in particular the observa-
tion that the P1‐C1 and C1–C2 bond lengths are shorter
than the normal values found for (P+–C (sp3)) and (C–C
TABLE 2 Crystal data and structure refinement for Y1 and 2
Compound Y1
Compound 2
Empirical formula
Formula weight
T [K]
C42H34O2P2Br2
792.45
C69H60.74Br6Cl2O2.37P4Pd2
1814.83
130.00(10)
orthorhombic
Pbca
130.00(10)
monoclinic
P21/c
Crystal system
Space group
a [Å]
15.72121(12)
8.79483(9)
25.5658(2)
90
21.2364(2)
19.1159(2)
16.81993(16)
90
b [Å]
c [Å]
α [°]
β [°]
90
99.6027(10)
90
γ [°]
90
V [Å3]
3534.86(6)
4
6732.43(13)
4
Z
ρ
calcg/cm3
1.489
1.790
μ [mm ¯1]
4.047
10.467
F(000)
1608.0
3558.7
2θ range [°]
6.91 to 154.23
7.056 to 154.232
Index ranges
−11 ≤ h ≤ 19, −11 ≤ k ≤ 10, −31 ≤ l ≤ 32
3733 [Rint = 0.0282, Rsigma = 0.0121]
3733/0/218
−26 ≤ h ≤ 23, −18 ≤ k ≤ 24, −20 ≤ l ≤ 21
14063 [Rint = 0.0437, Rsigma = 0.0370]
14063/4/782
Independent reflections
Data/restr./param.
Goodness‐of‐fit on F2
R1/wR2[I > 2σ(I)]
1.031
1.055
R1 = 0.0286, wR2 = 0.0710
R1 = 0.0452, wR2 = 0.1242

SABOUNCHEI ET AL.
7 of 14
TABLE 3 Selected bond lengths [Å] and bond angles [°] for Y1 and 2
Compound 2
Compound Y1
Mol 1
Mol 2
Bond distances
Br1–C5
1.9042(19)
1.260(2)
Pd1‐Br1
Pd1‐Br2
Pd1‐P1
Pd1‐C1
O1‐C2
2.4796(5)
2.5056(5)
2.2321(10)
2.139(4)
1.227(6)
1.497(6)
1.806(4)
1.795(4)
Pd2‐Br4
Pd2‐Br5
Pd2‐P3
Pd2‐C35
O2‐C36
C35‐C36
P4‐C55
2.4675(5)
O1–C2
2.4923(5)
2.2500(10)
2.122(4)
1.228(5)
1.485(6)
1.806(4)
1.808(4)
C1–C2
1.396(2)
P1‐C1
1.7203(15)
1.8148(16)
1.8071(16)
1.8090(16)
1.528(3)
P1‐C9
P1‐C10
C1‐C2
P1‐C16
P2‐C21
P1‐C29
C9‐C9i
P3‐C63
Bond angles
C1–P1–C9
C2–C1–P1
O1–C2–C1
C4–C5–Br1
P1‐C9‐C9i
113.41(7)
Br2‐Pd1‐Br1
C1‐Pd1‐P1
C1‐Pd1‐Br1
P1‐Pd1‐Br1
P1‐Pd1‐Br2
90.076(17)
95.88(11)
167.42(12)
86.57(3)
Br4‐Pd2‐Br5
C35‐Pd2‐P3
C35‐Pd2‐Br4
P3‐Pd2‐Br4
P3‐Pd2‐Br5
90.640(16)
93.76(11)
171.44(11)
87.78(3)
114.90(12)
122.17(15)
117.95(14)
111.25(14)
166.06(3)
175.27(3)
Symmetry Code: i 1‐x,1‐y,1‐z
angle between the keto group and the attached chlori-
nated aromatic ring in this latter compound is 59.9° for
molecule 1 and 61.9° for molecule 2.
The carbonyl oxygen is involved in two weak C‐H...O
hydrogen bonds, an intramolecular interaction between
the carbonyl oxygen and a methylene H‐atom, and an
intermolecular C‐H...O interaction that links the mole-
cules into a chain lying along the b‐axis.
angle between the bromo‐substituted aromatic ring and
the keto group is 23.1(2)°. The main difference between
the two molecules is in the conformation of the six‐
membered palladacycle rings. For molecule 2–1, the ring
is in a chair conformation (P1, C22, P2, C1 lying in the
equatorial plane, with the rms deviation being 0.005 Å,
and with Pd1 and C21 in the axial positions), while for
molecule 2–2, the ring is in a highly distorted boat confor-
mation (Pd2, P4, C55, P3 lying in the equatorial plane, with
the rms deviation being 0.281 Å, and with C35 and C56 in
the axial positions).
3.3.2 | Crystal structures of 2
Both molecules show weak intermolecular and intra-
molecular and C‐H … O and C‐H … Br hydrogen bonds,
the intermolecular C‐H … Br hydrogen bonds link the
molecules along the c‐axis (see Figure 3).
There are two crystallographically independent molecules
in the asymmetric unit. For molecule 2–1 the Pd is in a
slightly tetrahedrally distorted square planar environ-
ment, comprising two cis‐coordinating Br atoms, one
phosphorous atom and an ylid carbon; the rms deviation
of the four coordinating atoms, for molecule 2–1 is
0.260 Å, with Pd1 lying 0.0094(13) Å out of the least
squares plane. The keto oxygen is oriented away from
the Pd atom, the torsion angle Pd1 ‐ C1 ‐ C2 ‐ O1 being
99.4(4)°, while the dihedral angle between the bromo‐
substituted aromatic ring and the keto group is 7.3(4)°.
For molecule 2–2 the distortion from ideal square planar
geometry is somewhat greater; the rms deviation of the
four coordinating atoms is 0.415 Å, with Pd2 lying
0.1697(9) Å out of the least squares plane. The keto oxy-
gen is oriented away from the Pd atom, the torsion angle
Pd2 ‐ C35 ‐ C36 ‐ O2 being 96.9(4)°, while the dihedral
3.4 | Catalytic activity
3.4.1 | Optimization of reaction using
Taguchi method
The catalytic activity of complexes 1 and 2 in the
Mizoroki‐Heck coupling reaction of aryl chlorides with
ethyl acrylate was examined. The Taguchi method is a
statistical approach to optimize the process parameters
and can be expanded to improve the performance of total
quality control[28] and involves identification of the
appropriate control factors to obtain the optimum results

8 of 14
SABOUNCHEI ET AL.
FIGURE 3 Intramolecular interaction between of the molecules 2–1 and 2–2
of the process. Initially, we set up a systematic optimiza-
TABLE 5 L16 orthogonal array and experimental results
tion of reaction conditions using the Taguchi L16 experi-
mental design. Orthogonal Arrays (OA) are used to
conduct a set of experiments. In this work, the orthogonal
array (OA), signal‐to‐noise ratio and the analysis of vari-
ance are employed to study the performance characteris-
tics on response.[29] To select an appropriate orthogonal
array for conducting the experiments, the degrees of free-
dom are to be computed. The three selected factors,
including the base (B), solvent (S) and catalyst loading
(C), were used with their levels (Table 4).[30]
The most suitable orthogonal array for experimenta-
tion is L16 array as shown in Table 5. Therefore, a total
16 experiments are to be carried out. Whereas, the full
factorial experimental design requires 34 = 81 different
experiments to evaluate the influencing factors. Results
of these experiments are used to analyze the data and pre-
dict the quality of components produced. Table 5 presents
the required experiments to optimize the batch system
which were designed using Taguchi method. Initially,
we carried out a model reaction to optimize the reaction
conditions including solvent, base and catalyst loading.
In each run, commonly used bases and solvents,
Factor
B
Yield (%) S/N ratio
Run
S
C
1
K2CO3
K3PO4
DMF
DMF
0.0050 88
0.0100 73
0.0010 60
0.0005 43
38.8897
37.2665
35.5630
32.6694
36.6502
35.9868
35.5630
34.4855
34.8073
33.9794
36.5215
35.5630
34.4855
35.2686
33.0643
33.6248
2
3
NaOAC DMF
4
NEt3
DMF
5
K2CO3
K3PO4
DMF/Water 0.0010 68
DMF/Water 0.0005 63
6
7
NaOAC DMF/Water 0.0050 60
8
NEt3
DMF/Water 0.0100 53
9
K2CO3
K3PO4
Ethanol
Ethanol
0.0005 55
0.0010 50
0.0100 67
0.0050 60
0.0100 53
0.0050 58
0.0005 45
0.0010 48
10
11
12
13
14
15
16
NaOAC Ethanol
NEt3
Ethanol
Water
K2CO3
K3PO4
Water
NaOAC Water
NEt3 Water
TABLE 4 Controllable factors and their levels
Factor Description Level 1 Level 2
Level 3 Level 4
B
S
Base
K2CO3 K3PO4
NaOAC NEt3
Solvent
Catalyst
DMF
0.01
DMF/Water Ethanol Water
0.001 0.005 0.0005
including organic and inorganic bases and polar protic
solvents to non‐polar aprotic solvents were tested. Also,
different amounts of catalyst loadings (mol %) were used
C
(mol %)

SABOUNCHEI ET AL.
9 of 14
in different temperatures to find optimum reaction condi-
tions. All experiments were repeated, and the yield per-
centage of reaction was calculated for each
experiment.[31]
orthogonal experiment. To conclude the optimum condi-
tions for yield of experiments, we used the relationship
between each parameter and their percentage contribu-
tion ρand the analysis of variance (ANOVA).[33–35] F‐
Statistics also illustrates the significance of each factor
on the response quality.
The contribution percentage of each factor was shown
in Figure 5 while Table 6 shows the ANOVA results
obtained from the experimental data; the factors with
highest F‐value have highest contribution percentage on
the yield. Based on Table 6, it is clear that all three factors
make an equally important contribution to the yield from
the Mizoroki‐Heck coupling reaction. A comparison of
the experimental and the predicted yield of the reaction
We applied the signal‐to‐noise (S/N) ratio to evaluate
the experimental data, the S/N ratio analysis chosen was
the larger‐the‐better.[32] According the values of mean
S/N ratio is shown in Table 5 and the optimum level of
each factor was determined from the highest value of
S/N ratio revealed in Figure 4. The optimum condition
was found to be base: K2CO3, K3PO4, solvent: DMF,
DMF/Water and catalyst loading (mol %): 0.005, 0.01.
Analysis of variance (ANOVA) is used to evaluate the
response magnitude in (%) of each parameter in the
FIGURE 4 Main effect of each factor by S/N ratios
FIGURE 5 Contribution percentage of
factors for yield of Suzuki coupling
reaction

10 of 14
SABOUNCHEI ET AL.
TABLE 6 Results of the analysis of variance (ANOVA)
have shown in Figure 6 and the variation of the mean
yield values against various extraction parameters shown
in Figure 7.
Source DFa Seq. SSb Adj. SSc Adj. MSd Fe ρ(%)
S
3
472
472
500
0
472
472
500
0
157.333
157.333
166.667
0.000
*
*
*
24.28
24.28
25.72
The surface plots shown in Figure 8 helps to better dis-
play the effects of the experimental factors on the per-
centage yield. The effects of solvent and base, as shown in
Figure 8a, indicate that polar solvents such as DMF and
DMF/Water were more efficient in increasing the yield
of the products, to 88%. However, the reactions in ethanol
and water did not proceed even after prolonged stirring at
reflux temperature, probably due to the low solubility of
the complexes in this protic solvent. The effect of differ-
ent mineral bases on this reaction was investigated by
using the coupling of p‐CHO‐Ph‐Cl with ethyl acrylate
B
3
C
3
Error
Total
3
15
1944
aDF: degree of freedom.
bSeq.SS: sequential sum of squares.
cAdj.SS: adjusted sum of squares.
dAdj.MS: adjusted mean of squares.
eF: variance ratio.
FIGURE 6 Comparison of experimental and predicted yield of reaction
FIGURE 7 The response graph illustrates the variation of the mean yield values plotted against various extraction parameters

SABOUNCHEI ET AL.
11 of 14
FIGURE 8 Response surface plots for
the interaction between factors

12 of 14
SABOUNCHEI ET AL.
TABLE 7 Mizoroki‐Heck coupling reaction of aryl chlorides cat-
alyzed by complexes 1 and 2a
3.4.2 | Mizoroki‐heck coupling reaction of
functionalized aryl chlorides
Using the optimized reaction conditions, complexes 1 and
2 were applied in the reaction of various functionalized
aryl chlorides bearing both electron‐donating to
electron‐withdrawing groups with olefin. Aryl chlorides
were converted into the corresponding coupled products
in high to excellent yields (Table 7).
Yield
Entry R
Catalyst Product
(%)b
1
2
CH3
CH3
1
2
84
88
(5a)
(5b)
(5c)
A comparison between the catalytic activities of pre-
sented complexes and other Pd catalysts having different
ancillary ligands in Suzuki‐Miyaura reaction was carried
out. The results indicated that the differences in catalytic
behavior demonstrated in Table 8 should be ascribed not
only to the differences in the experimental conditions (e.
g. effects of solvent, base, and catalyst loading), but
mainly attributed to the characteristic differences in the
Pd content. The donor atoms of ligand have substantial
effect on stabilization and consequently performance of
Pd catalyst and the ligand‐controlling conditions is
clearly obvious in such catalytic reactions carried out
under similar experimental conditions. Compound 2
seems to give the best results in accordance with
Table 8.
3
4
CHO
CHO
1
2
95
98
5
6
NO2
NO2
1
2
93
95
7
8
H
H
1
2
84
88
(5d)
9
10
COCH3
COCH3
1
2
88
90
(5e)
aReaction conditions for Mizoroki‐Heck coupling reaction: aryl chloride
(0.5 mmol), olefin (0.75 mmol), K2CO3 (1 mmol), DMF (2 ml), catalyst
1and 2 (0.005 mmol), in air.
bIsolated yield.
4 | CONCLUSIONS
as a test case. K2CO3 and K3PO4 were the best choice of
base and the yield of product could be increased to 88%.
The interaction surface plot of the catalyst loading
(mol%) and solvent, as shown in Figure 8b indicate that
the percentage yield is higher in DMF and DMF/Water,
and with a catalyst loading (mol%) of 0.005. The effects
of solvent, base and catalyst loading (mol %), as shown in
Figure 6c, and confirm above results.
The present study describes the synthesis and characteri-
zation of new diphosphinium salt S diphosphine ylide Y1
and complexes 1 and 2 derived from PdBr2COD and
bifunctionalized phosphorus ylides (Y1 and Y2) by simple
and convenient synthetic methods in satisfactory yields.
These compounds were characterized using FT‐IR, and
NMR (1H, 13C and 31P) analyses as well as X‐ray struc-
tural analyses. The catalytic activity of complexes 1 and
TABLE 8 Comparison of Mizoroki‐Heck coupling reaction of p‐nitrochlorobenzene and ethyl acrylate using palladacycle 2 and other
catalytic system
Catalyst loading
(mmol)
Yield
(%)
Entry Pd source
Condition
Ref.
1
2
Pd (II)‐NHC complexes
0.5
0.1
K3PO4, DMA, 110 °C, 5 hr 52–90
36
37
[(C3H5)PdCl]2‐N,N,N′,N′‐tetra (diphenylphosphinomethyl)‐
1,2‐ethylenediamine
NaHCO3, DMF:
96
DMA,120 °C, 20 hr
3
4
5
Oxime‐Derived Palladium Complexes
PdCl2(MeCN)2
0.5
K2CO3, DMF, 130 °C, 5 hr 77
K3PO4, DMF, 130 °C, 24 hr 69
K2CO3, DMF, 130 °C, 6 hr 95
38
0.05
0.005
39
P, C‐chelated phosphorus ylide Pd (II)
This
work

SABOUNCHEI ET AL.
13 of 14
[8] R. E. Cramer, S. Roth, F. Edelmann, M. A. Bruck, K. C. Cohn,
2 toward Mizoroki‐Heck cross‐coupling reaction has been
investigated while the Taguchi method has been used to
optimize the yield of the products of the Mizoroki‐Heck
coupling reaction. The results also indicate that utiliza-
tion of the Taguchi method gives a suitable approach
for optimization of the yield of the Mizoroki‐Heck cou-
pling. The effect of each factor was estimated using indi-
vidual contributions as response functions. The results of
ANOVA showed that the all factors (solvent, base and
catalyst (mol%) have significant effect on the yield and
have highest F and high contribution percentage on the
yield of Mizoroki‐Heck coupling process.
J. W. Gilje, Organometallics 1989, 8, 1192.
[9] M. M. Ebrahim, H. Stoeckli‐Evans, K. Panchanatheswaran,
Polyhedron 2007, 26, 3491.
[10] E. C. Spencer, M. B. Mariyatra, J. A. K. Howard, A. M.
Kenwright, K. Panchanatheswaran, J. Organomet. Chem.
2007, 692, 1081.
[11] S. J. Sabounchei, M. Panahimehr, M. Ahmadi, Z. Nasri, H. R.
Khavasi, J. Organomet. Chem. 2013, 723, 207.
[12] S. J. Sabounchei, M. Panahimehr, M. Ahmadi, F. Akhlaghia, C.
Boscovic, C. R. Chim. 2014, 17, 81.
[13] S. J. Sabounchei, M. Ahmadi, Z. Nasri, E. Shams, S.
Salehzadeh, Y. Gholiee, R. Karamian, M. Asadbegy, S. Samiee,
C. R. Chim. 2013, 16, 159.
[14] B. L. Shaw, S. D. Perera, Chem. Commun. 1998, 17, 1863.
ACKNOWLEDGEMENTS
[15] L. D. Deborah, D. K. B. Maarten, P. F. Gino, G. V. Johannes, W.
Funding of our research from the Bu‐Ali Sina University
is gratefully acknowledged.
N. M. Piet, C. J. K. Paul, Eur. J. Inorg. Chem. 2012, 10, 1660.
[16] A. Ghorbani‐Choghamarani, A. Naghipour, H. Babaee, B.
Notash, Polyhedron 2016, 119, 517.
[17] S. J. Sabounchei, M. Ahmadi, Cat. Com. 2013, 37, 114.
SUPPLEMENTARY MATERIAL
[18] S. J. Sabounchei, A. Sedghi, A. Hashemi, M. Hosseinzadeh, M.
Physical measurements and selected 31P, 13C and 1H
NMR spectra of some compounds can be found in the
online version. CCDC 1431939 and 1812607 contains
the supplementary crystallographic data for the com-
plexes 1 and 2, respectively. These data can be obtained
free of charge via www.ccdc.cam.ac.uk/data_request/cif
or from the Cambridge Crystallographic Data Center,
12, Union Road, Cambridge CB2 1EZ, UK. Tel.: +44 0
1223 762911; or deposit@ccdc.cam.ac.uk.
Bayat, R. W. Gable, Appl. Organomet. Chem. 2017, 31, 3850.
[19] S. J. Sabounchei, A. Hashemi, M. Hosseinzadeh, S. Salehzadeh,
F. Maleki, Catal. Lett. 2017, 147, 2319.
[20] H. Yuan Yen, J. Yan Li, J. Environ. Manage. 2015, 161, 344.
[21] D. Drew, J. R. Doyle, A. G. Shaver, Inorg. Synth. 1972, 13, 47.
[22] O. V. Dolomanov, L. J. Bourhis, R. W. Grosse‐Kunstleve, P. D.
Adams, R. J. Gildea, J. A. K. Howard, H. Puschmann, J. Appl.
Crystallogr. 2011, 44, 1259.
[23] G. M. Sheldrick, Acta Crystallogr. A 2015, C71, 3.
[24] G. M. Sheldrick, Acta Crystallogr. 2015, A71, 3.
[25] M. Carbo, N. Marin, R. Navarro, T. Soler, E. P. Urriolabeitia,
ORCID
Eur. J. Inorg. Chem. 2006, 2006, 4629.
Seyyed Javad Sabounchei
9000-5304
https://orcid.org/0000-0001-
[26] S. J. Sabounchei, S. Samiee, D. Nematollahi, A. Naghipour, D.
M. Morales, Inorg. Chim. Acta 2010, 363, 3973.
[27] S. J. Sabounchei, H. Nemattalab, H. R. Khavasi, X‐Ray Struct.
Anal. Online 2010, 26, 35.
REFERENCES
[28] P. J. Ross, Taguchi techniques for quality engineering, McGraw‐
Hill, Singapore 1996.
[1] E. C. Spencer, M. B. Mariyatra, J. A. K. Howard, A. M.
Kenwrigh, K. J. Panchanatheswaran, Organomet. Chem. 2007,
5, 1081.
[29] M. A. Schoonen, J. M. T. Schoonen, J. Colloid Interface Sci.
2014, 422, 1.
[2] S. J. Sabounchei, M. Ahmadi, F. AkhlaghiBagherjeri, H. R.
[30] M. P. Elizalde‐González, L. E. Garcia‐Diaz, Chem. Eng. J. 2010,
163, 55.
Khavasi, J. Chem. Sci. 2013, 3, 653.
[3] S. J. Sabounchei, A. Hashemi, A. Yousefi, P. Gohari
Derakhshandeh, R. Karamian, M. Asadbegy, K. Van Hecke,
Polyhedron 2017, 135, 1.
[31] J. Zolgharnein, N. Asanjarani, T. Shariatmanesh, Int.
Biodeterior. Biodegrad. 2013, 85, 66.
[32] B. Ramavandi, G. Asgari, J. Faradmal, S. Sahebi, B. Roshani,
[4] D. Aguilar, M. A. Aragues, R. Bielsa, E. Serrano, T. Soler, L. R.
Korean J. Chem. Eng. 2014, 31, 2207.
Navarro, E. P. Urriolabeitia, J. Organomet. Chem. 2008, 3, 417.
[33] S. Athreya, Y. D. Venkatesh, Int. Refereed J. Eng. Sci. 2012,
1, 13.
[5] A. Spannenberg, W. Baumann, U. Rosenthal, Organometallics
2000, 19, 3991.
[34] C. S. Chou, R. Y. Yang, J. H. Chen, S. W. Chou, Powder
Technol. 2010, 199, 264.
[6] S. J. Sabounchei, M. Hosseinzadeh, S. Salehzadeh, F. Maleki, R.
W. Gable, Inorg. Chem. Front. 2017, 2017, 4.
[35] N. J. Cox, J. Warburton, A. Armstrong, V. J. Holliday, Earth
Surf. Process. Landf. 2008, 33, 25.
[7] E. C. Spencer, B. Kalyanasundari, M. Baby Mariyatra, J. A. K.
Howard, K. Panchanatheswaran, Inorg. Chim. Acta 2006,
359, 35.
[36] K. R. Balinge, P. R. Bhagat, C. R. Chim. 2017, 20, 773.

14 of 14
SABOUNCHEI ET AL.
[37] X.‐J. Yu, R. Zhou, Y. Zhang, H. Yan Fu, R. Xiang Li, H. Chen,
X. Jun Li, Cat. Com. 2010, 12, 222.
How to cite this article: Sabounchei SJ, Badpa
[38] D. A. Alonso, C. Najera, M. C. Pacheco, Adv. Synth. Catal. 2002,
67, 5588.
K, Hashemi A, Moniriyan F, Gable RW. Spectral
and crystallography studies of new palladacycle
complexes with P,C‐ and C,C‐donor ligands;
Application of (OAL16) to optimizing the yield of
Mizoroki‐Heck reaction. Appl Organometal Chem.
2019;e4882. https://doi.org/10.1002/aoc.4882
[39] T. Mino, Y. Shirae, Y. Sasai, M. Sakamoto, T. Fujita, J. Org.
Chem. 2006, 71, 6834.
SUPPORTING INFORMATION
Additional supporting information may be found online
in the Supporting Information section at the end of the
article.