New dimeric phosphine ylide copper (I) complexes: Synthesis, coordination behavior, and application in Suzuki cross-coupling reactions

Article abstract of DOI:10.1016/j.inoche.2013.08.010

The reaction of the non-symmetric phosphorus ylides, Ph ₂P(CH₂)_nPPh₂C(H)C(O)PhR with CuCl in equimolar ratios using dry methanol as solvent give binuclear complexes of the type [Cu(μ-Cl){Ph₂P(CH₂)_nPPh ₂C(H)C(O)PhR}]₂ (n = 1: R = Br (1), OCH₃ (2); n = 2: R = Br (3), OCH₃ (4)). X-ray analyses of 1 demonstrate the Cl bridged dimeric structures with P,C-chelated ligands. Characterizations of these compounds were carried out by FT-IR and multinuclear NMR technique. Elemental analysis indicate a 1:1 stoichiometry between the ylides and the Cu(I) chloride in the four complexes. The precursor complexes 1 and 3 are found to exhibit high catalytic activity in the Cu-catalyzed Suzuki cross-coupling reactions in an air atmosphere at medium catalyst loading in DMF as a solvent. The use of 5 mol% catalyst in the presence of Cs₂CO₃ allows the coupling reaction to proceed with moderate to excellent yields.

Full text of DOI:10.1016/j.inoche.2013.08.010

Inorganic Chemistry Communications 36 (2013) 39–44
Contents lists available at ScienceDirect
Inorganic Chemistry Communications
journal homepage: www.elsevier.com/locate/inoche
New dimeric phosphine ylide copper (I) complexes: Synthesis,
coordination behavior, and application in Suzuki cross-coupling reactions
a
a
a
b
Seyyed Javad Sabounchei a, , Mahbubeh Pourshahbaz , Mohsen Ahmadi , Ali Hashemi , Hamid Reza Khavasi
⁎
a
Faculty of Chemistry, Bu-Ali Sina University, Hamedan, 65174, Iran
Department of Chemistry, Shahid Beheshti University, G.C., Evin, Tehran 1983963113, Iran
b
a r t i c l e i n f o
a b s t r a c t
Article history:
The reaction of the non-symmetric phosphorus ylides, Ph2P(CH2)nPPh2C(H)C(O)PhR with CuCl in equimolar ratios
using dry methanol as solvent give binuclear complexes of the type [Cu(μ-Cl){Ph2P(CH2)nPPh2C(H)C(O)PhR}]2
(n = 1: R = Br (1), OCH3 (2); n = 2: R = Br (3), OCH3 (4)). X-ray analyses of 1 demonstrate the Cl bridged dimer-
ic structures with P,C-chelated ligands. Characterizations of these compounds were carried out by FT-IR and multi-
nuclear NMR technique. Elemental analysis indicate a 1:1 stoichiometry between the ylides and the Cu(I) chloride in
the four complexes. The precursor complexes 1 and 3 are found to exhibit high catalytic activity in the Cu-catalyzed
Suzuki cross-coupling reactions in an air atmosphere at medium catalyst loading in DMF as a solvent. The use of 5
mol% catalyst in the presence of Cs2CO3 allows the coupling reaction to proceed with moderate to excellent yields.
© 2013 Elsevier B.V. All rights reserved.
Received 14 June 2013
Accepted 10 August 2013
Available online 19 August 2013
Keywords:
Phosphorus ylide
Cu(I) complex
X-ray crystal structure
Suzuki cross-coupling reaction
High catalytic activity
Copper-catalyzed
Phosphorus ylides are a group of very interesting ligands in organo-
metallic chemistry; these compounds are also useful intermediates in or-
ganic synthesis and have been used as reducing agents in coordination
chemistry [1–4]. The utility of metalated phosphorus ylides in synthetic
chemistry has been well documented [5–7]. The α-ketostabilized ylides
derived from bisphosphines, viz., Ph2PCH2PPh2 = C(H)C(O)R and Ph2-
PCH2CH2PPh2 = C(H)C(O)R (R = Me, Ph or OMe) [8], constitute an
important class of hybrid ligands containing both phosphine and ylide
functionalities and can exist in ylidic and enolate forms. These ligands
can therefore engage in different kinds of bonding with metal ions
[8–19]. P,C-coordination mode of stabilized phosphorus ylides have
been previously observed for Pd(II), Pt(II), Rh(I), Hg(II) species [8–18].
In 1975, Yamamoto et al. [20] reported Cu(I) complexes of phosphorus
ylides of the type (C6H5)3PCHR (R = H, CH3, CH(CH3)2). The use of cop-
per complexes in the Suzuki coupling has been studied in recent years.
Suzuki cross-coupling reactions have proven to be important transfor-
mations, as the resulting biaryl products are extremely valuable interme-
diates in organic synthesis, natural products, and biological molecules
[21–27]. The general Suzuki coupling procedures involves the use of
palladium phosphine complexes as catalysts [21–23]. Nevertheless, the
high price of Pd renders commercial processes based on Pd less attractive
unless extremely active and/or recyclable catalysts are available. For
these reasons, much recent attention has been attracted on employing
less expensive transition metal catalyst complexes, [23–33] in particular,
copper, to replace the palladium. However, only a few copper-catalyzed
Suzuki cross-coupling procedures exist [21–23,28,29,34,35]. Phosphorus
ylides as a particular ligand has been specially used in C–C coupling reac-
tions. Our previous research showed that symmetrical and non-
symmetrical phosphorus ylides are versatile ligands and their palladium
complexes are quite efficient cross-coupling catalysts [36–39]. Excellent
activities observed with Pd (II) complexes of phosphine ylide ligands
encouraged us to explore the chemistry of copper compounds. In the
first, we have now focused our attention in the study of the coordination
modes adopted by the resonance stabilized ylides when ligated to
Cu(I). Second, we have worked on catalytic activity of the new copper
(I) phosphine mono-ylide Complexes 1 and 3 in Suzuki cross-coupling
reactions.
Reaction of the ligands with CuCl in methanol (1:1) yielded the
binuclear complexes [40]. The X-ray structure of complex 1 demon-
strates the five-membered chelate ring in which the ligands were che-
lated to the metals through the free phosphine group and the ylidic
carbon atom. The 31P NMR spectra of complexes 1 and 2 show two dou-
blets that indicate the presence of the PCH and PPh2 groups in these
molecules (see Supplementary material). The significant downfield
shift of the signals due to PCH groups indicates C-coordination of the li-
gand to Cu center [15]. The strong downfield shifting and broadening of
doublets of PPh2 groups due to rapid equilibrium with non-coordinated
forms is other clear evidence for P-coordinating of the ligands [15]. The
identical pattern in chemical shift values in the 31P NMR spectra of com-
plexes 3 and 4 suggest similar structures with complexes 1 and 2. The P,
C-chelation of ligands has been previously observed for mercury halide
and palladium complexes [41–43]. The downfield shift and broadening
of the doublet signal was observed due to methinic (PCH) group in the
1H NMR spectra of complexes 1 and 2 [41]. Similar behavior was ob-
served earlier in the case of ylide complexes of platinum(II) chloride
⁎
Corresponding author. Tel: +98 811 8282807; fax: +98 811 8380709.
E-mail address: jsabounchei@yahoo.co.uk (S.J. Sabounchei).
1387-7003/$ – see front matter © 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.inoche.2013.08.010

40
S.J. Sabounchei et al. / Inorganic Chemistry Communications 36 (2013) 39–44
Two ylidic ligands are, respectively, located on the opposite sides to
minimize the repulsion between them. The angles subtended by the li-
gand at the Cu(I) center in 1 vary from 93.48 to 126.11, indicating a
distorted tetrahedral environment. The Cu–P bond lengths (~2.19 Å)
are in the usual range for Cu(I) complexes. The Cu · · · Cu distance of
3.115 Å (1) is longer than two van der Waals radii for copper (2.8 Å)
[51], indicating the absence of significant bonding interactions between
the Cu atoms in the molecular structures (see Fig. 2). The non-classical
C–H…Cl and C = O…H–C hydrogen bonds determine the structural as-
sembly in this compounds and are shown in supplementary material
(Fig. S1).
It is well established that palladium complexes containing phosphine
ligands, which combines both good donor strength and π-accepting ca-
pacity, always have a high catalytic activity in Suzuki cross-coupling
reactions [52–55]. The copper-catalyzed Suzuki cross-coupling reac-
tion has received a lot of attention in the past few years and has al-
ready been reviewed [28,34,56–60]. Based on these prior examples,
our group began a study of using phosphine mono-ylide copper (I)
complexes 1 and 3 for Suzuki cross-coupling reactions in the first
time. These copper complexes are soluble in a variety of organic sol-
vents that have been shown to be effective as additives in the modern
copper-catalyzed cross-coupling reactions. These reactions are general,
tolerate a variety of functional groups and substrates, avoid the use of
expensive and/or air-sensitive additives and overcome some of the
limitations of the palladium-catalyzed analogues. The model reaction
of iodobenzene with phenylboranic acid achieved maximum yields
when Cs2CO3 was used as a base, DMF as a solvent, and the reaction
occurred at 130 °C under aerobic conditions (see Ref. [36,37,39]).
Catalyst loading tests were performed to determine the catalytic effi-
ciency of the catalyst in the presence of DMF and Cs2CO3. In order to op-
timize the reaction condition for the coupling reactions, different
amounts of catalyst (mol%) were taken and the results are summarized
in Table S3 (see supplementary material). Various catalyst concentra-
tions were also tested and 5 mol% gave the best result. These are the in-
dications of an effective catalytic system that merits more downstream
explorations.
Fig. 1. X-ray crystal structure of 1. Hydrogen atoms are omitted for clarity.
[44]. In the case of complexes 3 and 4, these signals are weak and broad
due to low solubility in common solvents. The up-field shift of the sig-
nals due to ylidic carbons in the 13C NMR spectra of complexes 1 and
2 also are an evidence for C-coordination [45,46]. The 13C NMR shift of
the CO signal (180 to 187 ppm) with reference to the parent ylides in-
dicates a much lower shielding of the carbon of the CO group in these
complexes. Neither H-Cu nor P-Cu coupling was observed at room
temperature in the spectra; possibly a fast equilibrium between the
complexes and the free ylides is responsible for the failure to observe
NMR coupling or two diastereoisomers. The ν CO for ylides are observed
in lower frequencies than those of the related phosphonium salts as in
the case of other resonance stabilized ylides [47], suggesting some re-
moval of electron density in the C = O bond. As noted previously
[48–50], the coordination of the ylide through carbon or oxygen causes
a significant increase or decrease, respectively, in the ν (CO) frequency.
The infrared absorption bands observed for these complexes around
1540 cm−1 indicate coordination of the ylide through ylidic carbon
atom [15].
The crystals of complex 1 were grown by the slow evaporation of the
chloroform solution. An ORTEP diagram of the complex with atomic
numbering scheme is shown in Fig. 1. Relevant parameters concerning
data collection and refinement are given in supplementary material
and selected bond distances, and angles are collected in Table S1 and
Table S2, respectively.
The complex consists of centrosymmetrical dimeric units with the
two chlorine atoms bridging the two copper atoms. The tetrahedral co-
ordination of the copper atoms is achieved by P,C-chelating the ylide.
In the first, the four copper(I) complexes has been observed to
catalyze the targeted coupling reactions, but because of their similar
structural and catalytic efficiency, we have investigated the catalytic ac-
tivity of complex 1 and 3 in this work. These Cu(I) complexes were used
for the first time in Suzuki cross-coupling reactions.
Under above conditions (base: Cs2CO3; solvent: DMF; temperature:
130 °C), we examined the scope of the reaction of phenylboranic acid
with various aryl halides bearing electron-donating and electron-
withdrawing groups in the presence of 5 mol% of catalyst 1 and the
results are shown in Table 1. A number of aryl iodides, bromides, and
Fig. 2. Selected bond lengths and bond angles for 1.

S.J. Sabounchei et al. / Inorganic Chemistry Communications 36 (2013) 39–44
41
chlorides have been successfully coupled with phenylboranic acid.
Electron-donating groups (Table 1, 3a, 11a and 13a) and electron-
withdrawing groups (Table 1, 1a, 2a, 6a, 8a and 10a) were successfully
coupled to phenylboranic acid in moderate to good yields. Moderate
yields are realized for the coupling of electronically deactivated
4-methyl bromobenzene with phenylboronic acid (Table 1, 3a, 62%).
This condition also allows for the coupling of 2-bromothiophene as
a heterocyclic substrate (Table 1, 7a, 60%). It is notable that the use
of deactivated aryl bromides (Table 1, 3a) as well as activated or
electron-poor ones (Table 3, 1a, 2a and 8a) also resulted in good yields.
However, the coupling of neutral bromobenzene with phenylboronic
acid resulted in coupling with good yield (Table 1, 5a, 63%). As expected,
satisfactory results were obtained with the 1-bromonaphthalene of
the phenylboronic acid (Table 1, 4a, 62%). Then, we tried to examine
whether aryl chlorides were active for the Suzuki reaction. Generally,
it is difficult to activate C–Cl bonds because of their relative inertness
[61–63]. Despite the economical advantages of employing aryl chlorides
in the Suzuki reaction, an electron neutral chlorobenzene resulted in a
41 % yield (Table 1, 9a), and a moderate yield was obtained with an ac-
tivated chloroarenes (Table 1, 10a, 50%). The reaction of chlorotoluene
proceeded smoothly to provide the desired product in poor yield
(Table 1, 11a, 40%). The experimental data showed that the order of re-
activity of the phenyl halides is PhI N PhBr N PhCl with the iodobenzene
being most active toward coupling reactions (Table 1, 12a, 82%). It
was gratifying to note that 4-methyl iodobenzene underwent coupling
reaction with phenylboronic acid to afford high yield of desired products
under similar condition (Table 1, 13a, 83%). The efficiency of Cu(I)
phosphine catalyst precursor relative to Pd(II) catalysts is attributed
to the electronic modification of the coordinated phosphorus ylides
and bulkiness of the phosphine ligands [64,65].
The catalytic activity of 3 was then evaluated for the Suzuki cross-
coupling reaction. In an effort to understand how the complexes 1
(containing five-membered P,C-chelate ring) and 3 (six-membered
P,C-chelate ring) could promote the Suzuki cross-coupling reaction
most efficiently, different steric properties of phosphine moieties
and backbones (derived from dppm or dppe) were examined under
similar reaction conditions. The complexes of bulky phosphine li-
gands is presumed to be able to accelerate the reaction rate and per-
ceived as a potential candidate for an effectively catalytic performance
[64–67].
Therefore, we have checked the six-member ring catalyst precursor
3 in Suzuki cross-coupling reaction. Using the available optimal con-
ditions, the scope of the Suzuki cross-coupling reaction was investi-
gated. High catalytic efficiencies were observed for the coupling of a
variety of aryl halides with phenylboronic acid (see Table 1). As can
be seen in Table 3, the electron-withdrawing groups (Table 1, 1a
(85%), 2a (80%), 8a (85%), and 10a (63%)) and electron-donating
groups (Table 1, 3a (82%), 11a (61%)) were successfully coupled to
phenylboronic acid in good to excellent yields. For instance, the reactions
between 4-bromonitrobanzene and phenylboronic acid can be carried
out using 5 mol% of 3 in 24 h at 130 °C to give the corresponding of the
products (Table 1, 1a (85%)). The products obtained from the coupling
of 1-bromonaphthalene and 2-bromothiophene with phenylboronic
acid resulted in 80% and 77% yield, respectively (Table 1, 4a and 7a).
We further investigated the catalytic activity for the coupling of aryl
chloride and their derivatives efficiently reacted with phenylboronic
Table 1
Suzuki cross-coupling reaction of various aryl halides with phenyl boronic acid catalyzed by Cu (I) complexes 1 and 3.a
B(OH)2
X
+
Cs2CO3, DMF
5 mol% cat.
R
R
1a-13a
Br
Cl
Br
O
O
Ph
Ph
Cl
Ph
P
Ph
P
Cu
Ph
Cu
P
2
P
2
Ph
Ph
Ph
Cat. 1
Cat. 3
Ar-X
p-O2N-Ph-Ph
Product no.
Catalysts (yield %)c
p-O2N-Ph-Br
p-OHC-Ph-Br
p-Me-Ph-Br
C10H7-Brd
Ph-Br
p-OHC-Ph-Ph
p-Me-Ph-Ph
C10H7-Ph
Ph-Ph
p-HO2C-Ph-Ph
C4H3S-Ph
C4H3S-Ph
p-CH3OC-Ph- Ph
Ph-Ph
p-CH3OC-Ph- Ph
p-Me-Ph-Ph
Ph-Ph
1a
2a
3a
4a
5a
6a
7a
8a
1 (64), 3 (85)
1 (61), 3 (80)
1 (62), 3 (82)
1 (62), 3 (80)
1 (63), 3 (83)
1 (67), 3 (85)
1 (60), 3 (77)
1 (65), 3 (85)
1 (41), 3 (57)
1 (50), 3 (63)
1 (40), 3 (61)
1 (82), 3 (91)
1 (83), 3 (93)
p-Br-Ph-CO2H
C4H3SBre
p-CH3OC-Ph-Br
Ph-Cl
p-CH3OC-Ph-Cl
p-Me-Ph-Cl
Ph-I
9a
10a
11a
12a
13a
p-Me-Ph-I
p-Me-Ph-Ph
aReaction conditions: aryl halide (0.5 mmol), phenylboronic acid (0.75 mmol), Cs2CO3 (1.5 mmol), DMF (2 ml), catalyst (5 mol%), 130 °C, 24 h, under air.
bProducts were identified by comparison of their 1H and 13C NMR spectral data those reported in the literature (see Ref. [36,37]).
c Isolated yields.
d 1-Bromonaphthalene.
e2-Bromothiophene.

42
S.J. Sabounchei et al. / Inorganic Chemistry Communications 36 (2013) 39–44
Table 2
Compression with other catalytic system catalyzed with Cu(I) complexes.
Cu catalyst
X +
B(OH)2
R1
R1
Entry
Aryl halide
[Cu] catalyst
Cu colloid
mol%
Conditions
Yield (%)
Ref.
1
2
3
4
5
p-Me-Ph-I
p-OHC-Ph-Br
p-O2N-Ph-Br
p-I-Ph-I
Ph-Br
Ph-I
Ph-Br
p-Me-Ph-I
Ph-Br
2
5
K2CO3, DMF, 110 °C, 8 h
Cs2CO3, PEGa, 120 °C, 24 h
Cs2CO3, DMF, 130 °C, 24 h
Cs2CO3, DMF, 130 °C, 24 h
K2CO3, PEG, 140 °C, 36 h
K2CO3, PEG, 110 °C, 12 h
Cs2CO3, DMF, 130 °C, 24 h
100
90
28
80
91
99
63
83
83
93
[28]
[35]
[58]
[59]
[75]
[75]
This work
[{Cu(N-(aryl)pyridine-2-aldimines)I}2]
CuI/DABCO b
10
10
10
10
5
CuI/DABCO/TBAB c
Cu powder/I2
Cu powder
[Cu(μ-Cl){Ph2PCH2 Ph2C(H)C(O)PhBr}]2
6
7
[Cu(μ-Cl){Ph2P(CH2
CH2PPh2C(H)C(O)PhBr}]2
5
Cs2CO3, DMF, 130 °C, 24 h
This work
p-Me-Ph-I
aPolyethyleneglycol.
b1,4-Diaza-bicyclo[2.2.2]octane.
cn-Bu4NBr.
acid to yield biphenyls in good yields (Table 1, 9a–11a). The aryl iodides
bearing an electron-donating or neutral were obtained good yields
(Table 1, 12a (91%) and 13a (93%)).
concentration and selected 31P, 13C and 1H NMR spectra of some com-
pounds can be found in the online version. A representation of part of
the unit cell contents of 1 and crystal data and structure refinement
are presented supplementary material. The crystallographic data for
the structural analysis of 1 have been deposited with Cambridge crystal-
lographic center, CCDC No. 864861 Copies of this information may be
obtained free of charge from The Director, CCDC, 12 Union roads,
Cambridge.CB2 1EZ, UK (e-mail: deposit@ccdc.cam.ac.uk). Supplemen-
tary data to this article can be found online at http://dx.doi.org/10.1016/
j.inoche.2013.08.010.
As can be seen in Table 1, the reaction of aryl bromide with electron
donating group, catalyst 1 gave moderate yields of corresponding
products, whereas catalyst 3 further increased the yield (Table 1, 3a
(cat. 1, 62%, cat. 3, 82%) and 11a (cat. 1, 40%, cat. 3, 61%)). Comparatively,
catalyst 3 bears dppe groups on the backbone (forming of six-
membered ring) and thus could exhibit a certain steric hindrance on
the catalytic center. Similar to previous reports about bulky phosphine
ligands [68–71], the bulkier phosphine Cu(I) complex 3 showed higher
activities than their analogues 1. For example, catalyst 1 gave moderate
yield with neutral aryl halides (Table 1, 5a, 9a and 12a), which was
much less effective than that of catalyst 3. These results can be ascribed
to the increase in steric hindrance of the catalysts, leading to an increase
in the rate of the elimination process [72].
According to the literature [64–67,73–75], the best results for Suzuki
coupling of aryl halides were achieved with phosphorus-containing
complexes or with palladacycles modified by carbenes. A comparison
of catalytic efficiency among the most active Cu complexes known to
catalyze the Suzuki coupling of aryl halides with phenylboronic acid is
discussed in the Table 2. The catalyst precursors 1 and 2 were the first
examples of a unsymmetrical phosphine mono-ylide Cu(I) complexes
while allowing the use of various aryl halides in Suzuki coupling.
The present study describes the synthesis and characterization of first
Cu(I) complexes with stabilized phosphorus ylides. On the basis of the
physico-chemical and spectroscopic data, we propose P,C-coordination
to the metal, which is further confirmed by the X-ray crystal structures.
However, all previous studies focused on Pd(II) systems and no study
on the use of dinuclear phosphine mono-ylide Cu(I) complexes as
pre-catalysts in Suzuki reactions have been reported to date. The Cu(I)
complexes were found to be a highly active catalyst for the Suzuki
cross-coupling of a range of various aryl halides with phenylboronic
acid.
References
[1] C.G. Kokotos, V.K. Aggarwal, Aminals as substrates for sulfur ylides: a synthesis of
functionalized aziridines and N-heterocycles, Org. Lett. 9 (2007) 2099–2102.
[2] D. Janardanan, R.B. Sunoj, Computational Investigations on the general reaction pro-
file and diastereoselection in sulfur ylide promoted aziridinations, Chem. Eur. J. 13
(2007) 4805–4815.
[3] J. Heinicke, N. Peulecke, M. Kohler, M. He, W. Keim, Tuning of nickel
2-phosphinophenolates catalysts for oligomerization and polymerization of
ethylene, J. Organomet. Chem. 690 (2005) 2449–2457.
[4] O.I. Kolodiazhnyi, C-element-substituted phosphorus ylids, Tetrahedron 52 (1996)
1855–1929.
[5] G. Wagner, T.B. Pakhomova, N.A. Bokach, Reduction of (imine)Pt(IV) to (imine)
Pt(II) complexes with carbonyl-stabilized phosphorus ylides, Inorg. Chem. 40 (2001)
1683–1689.
[6] N.A. Bokach, V.Y. Kukushkin, M. Haukka, Pop-the-cork strategy in synthetic utiliza-
tion of imines: stabilization by complexation and activation via liberation of the li-
gated species, Inorg. Chem. 42 (2003) 3602–3608.
[7] H.J. Christau, Synthetic applications of metalated phosphonium ylides, Chem. Rev.
94 (1994) 1299–1313.
[8] Y. Oosawa, H. Urabe, T. Saito, Y. Sasaki, Preparation of chelate ylide ligands and their
palladium(II) and platinum(II) halide complexes, J. Organomet. Chem. 122 (1976)
113–121.
[9] A. Spannenberg, W. Baumann, U. Rosenthal, Palladium(II) complexes of α-stabilized
phosphorus ylides, Organometallics 19 (2000) 3991–3993.
[10] R. Uson, J. Fornies, R. Navarro, A.M. Ortega, Perhalophenyl complexes of palladium(II)
containing keto-stabilized phosphorus ylides of the type Ph2P(CH2)nPPh2CHC(O)R, J.
Organomet. Chem. 334 (1987) 389–397.
[11] I.J.B. Lin, H.C. Shy, C.W. Liu, L.-K. Liu, S.-K. Yeh, Mixed sulphur and phosphorus ylide
complexes of palladium formed by phase-transfer catalysis. X-Ray crystal structure
of [Pd{(CH2)2S(O)Me}{Ph2PCH2PPh2CHC(O)Ph}]I · CH2Cl2 · H2O, J. Chem. Soc.
Dalton Trans. (1990) 2509–2514.
Acknowledgements
[12] D. Saravanabharathi, T.S. Venkatakrishnan, M. Nethaji, S.S. Krishnamurthy, Rhodium(I)
complexes of a-keto-stabilised 1,2-bis(diphenylphosphino)alkane mono ylides, Proc.
Ind. Acad. Sci. (Chem. Sci.) 115 (2003) 741–749.
[13] L.R. Falvello, S. Fernandez, R. Navarro, E.P. Urriolabeitia, Reactivity of Pd(0) com-
plexes with the phosphino ylide [Ph2PCH2PPh2C(H)C(O)Me]. Molecular structure
of [Pd(PPh2CHPPh2C(H)C(O)Me)2], Inorg. Chem. 39 (2000) 2957–2960.
[14] H. Takahashi, Y. Oosawa, A. Kobayashi, T. Saito, Y. Sasaki, Crystal and molecular
structure of a chelating ylide complex of palladium [(benzoylmethylene)diphenyl-
2-(diphenylphosphino)-ethylphosphorane–dichloropalladium (II) toluene solvate,
Bull. Chem. Soc. Jpn. 50 (1977) 1771–1775.
We are grateful to the Bu-Ali Sina University for a grant and Mr.
Zebarjadian for recording the NMR spectra.
Appendix A. Supplementary material
The ligand preparation methods, materials and physical measure-
ments, X-ray crystallography data, determination of catalyst

S.J. Sabounchei et al. / Inorganic Chemistry Communications 36 (2013) 39–44
43
[15] M.M. Ebrahima, K. Panchanatheswaran, A. Neels, H. Evans, Mercury(II) complexes of
stabilized phosphine–phosphonium ylide derived from bis(diphenylphosphino)
methane: synthesis, spectra and crystal structures, J. Organomet. Chem. 694 (2009)
643–648.
[16] S.M. Sbovata, A. Tassan, G. Facchin, Synthesis and coordination of the
bifunctionalized ylides Ph2P(CH2)n(Ph)2P = CHCOOMe (n = 1, 2) and ketenylidene
Ph2P(CH2)2(Ph)2P = C = O to Pd and Pt complexes, Inorg. Chim. Acta 361 (2008)
3177–3183.
[17] M.M. Ebrahim, H. Evans, K. Panchanatheswaran, Reactivity of mercury(II) halides
with the unsymmetrical phosphorus ylide Ph2PCH2CH2PPh2 = (H)C(O)Ph:
crystal structure of {HgI2[PPh2CH2CH2PPh2 = C(H)C(O)Ph]}n, Polyhedron 26 (2007)
3491–3495.
[18] H. Takahashi, Y. Oosawa, A. Kobayashi, T. Saito, Y. Sasaki, Structure of a Chelate Ylide
Complex: dichloro(Benzoylmethylene-Diphenyl-2- Diphenylphosphinoethylphos
phorane)palladium, Chem. Lett. 5 (1976) 15–16.
113.22–161.96 (Ph), 188.09 (s, CO). General procedure for complexes 3–4: To a so-
lution of CuCl (0.5 mmol) in dry methanol (10 ml), a solution of phosphorus ylide
(0.5 mmol) also in dry methanol (10 ml) was added drop wise at 25 °C and stirred
for 7 h and then concentrated to a ca. 2 ml in volume and treated with n-hexane (ca.
15 ml) to afford a yellow solid. (3): Yield: 0.562 g (81 %). M.p. 125 °C (decom-
poses). Anal. Calc. for C68H58Br2Cl2Cu2O2P4: C, 58.81; H, 4.21. Found: C, 58.96; H,
4.46 %. IR (KBr, cm−1): 1513 (CO). 1H NMR (CDCl3): δH (ppm): 2.54 (br, 2H, CH2),
3.12 (br, 2H, CH2), 4.26 (br, 1H, PCH); 6.92–8.23 (m, 24H, Ph). 31P NMR (CDCl3):
3
δp (ppm): -10.42 (br, –PPh2), 15.46 (d, –PC(H), JP-P = 61.2 Hz). (4) Yield:
0.529 g (82 %). M.p. 110 °C (decomposes). Anal. Calc. for C70H64Cl2Cu2O4P4: C,
65.12; H, 5.00. Found: C, 65.41; H, 5.26 %. IR (KBr, cm−1): 1663 (CO). 1H NMR
(CDCl3): δH (ppm): 2.05 (br, 2H, CH2), 3.57 (br, 2H, CH2), 3.80 (s, 3H, OCH3), 5.60
(br, 1H, PCH), 6.71–7.98 (m, 24H, Ph). 31P NMR (CDCl3): δp (ppm): -10.58 (br. d,
–PPh,23JP-P = 55.0 Hz), 15.22 (d, –PC(H), 3JP-P = 59.3 Hz).
[41] S.J. Sabounchei, S. Samiee, D. Nematollahi, A. Naghipour, D. Morales-Morales,
Synthesis, characterization and structural studies of new palladium(II) com-
plexes including non-symmetric phosphorus ylides, Inorg. Chim. Acta 363 (2010)
3973–3980.
[42] S.J. Sabounchei, S. Samiee, S. Salehzadeha, Z.B. Nojini, E. Irran, Four-coordinate and
pseudo five-coordinate Hg(II) complexes of a new bidentate phosphorus ylide:
X-ray crystal structure and spectral characterization, J. Organomet. Chem. 695
(2010) 1441–1450.
[19] L.R. Falvello, M.E. Margalejo, R. Navarro, E.P. Urriolabeitia, Synthesis and characteriza-
tion of PdII complexes containing cyclic bis-ylides, Inorg. Chim. Acta 347 (2003) 75–85.
[20] Y. Yamamoto, H. Schmidbaur, Alkylidentriphenylphosphoran-komplexe von
kupper(I)- und silber(I)-chlorid: I. 21 komplexe, J. Organomet. Chem. 96 (1975)
133–138.
[21] N. Miyaura, A. Suzuki, Palladium-Catalyzed Cross-Coupling Reactions of Organoboron
Compounds, Chem. Rev. 95 (1995) 2457–2483.
[22] N. Miyaura, Cross-Coupling Reaction, Springer, Berlin, 2002.
[23] A. de Meijere, F. Diederich, Metal-Catalyzed Cross-Coupling Reactions, Wiley-VCH,
Weinheim, 2004.
[24] P. Siemsen, R.C. Livingston, F. Diederich, Acetylenic coupling: a powerful tool in mo-
lecular construction, Angew. Chem. Int. Ed. 39 (2000) 2632–2657.
[25] J. Hassan, M. Sevignon, C. Gozzi, E. Schulz, M. Lemaire, Aryl–aryl bond formation
one century after the discovery of the Ullmann reaction, Chem. Rev. 102 (2002)
1359–1470.
[43] S.J. Sabounchei, S. Samiee, S. Salehzadeha, Z.B. Nojini, E. Irran, M. Borowski, New
mononuclear mercury(II) complexes of a bifunctionalized ylide containing five-
membered chelate ring: spectral and structural characterization, Inorg. Chim. Acta
363 (2010) 3654–3661.
[44] J.A. Teagle, J.L. Burmeister, Synthesis of ortho-metalated palladium(II) and
platinum(II) complexes of phosphonium, arsonium and sulfonium ylids, Inorg.
Chim. Acta 118 (1986) 65–72.
[45] G. Facchin, R. Bertani, M. Calligaris, G. Nardin, M. Mari, Synthesis and character-
ization of palladium(II)-η3-allyl–ylide complexes. X-Ray crystal structure of
[PdCl(η3-2-MeC3H4){Ph3PC(H)COMe}], J. Chem. Soc. Dalton Trans. 6 (1987)
1381–1387.
[26] S.V. Ley, A.W. Thomas, Modern synthetic methods for copper-mediated C(aryl)–O,
C(aryl)–N, and C(aryl)–S bond formation, Angew. Chem. Int. Ed. 42 (2003)
5400–5449.
[27] I.P. Beletskaya, A.V. Cheprakov, Copper in cross-coupling reactions. The
post-Ullmann chemistry, Coord. Chem. Rev. 248 (2004) 2337–2364.
[28] M.B. Thathagar, J. Beckers, G. Rothenberg, Copper-catalyzed Suzuki cross-coupling
using mixed nanocluster catalysts, J. Am. Chem. Soc. 124 (2002) 11858–11859.
[29] S. Gu, J. Huang, X. Liu, H. Liu, Y. Zhou, W. Xu, Macrocyclic tetranuclear copper (I)
complex bearing a N-heterocyclic carbene ligand: synthesis, structure, and catalytic
properties, Inorg. Chem. Commun. 21 (2012) 168–172.
[30] D. Zim, V.R. Lando, J. Dupond, A.L. Monteiro, NiCl2(PCy3)2: a simple and efficient
catalyst precursor for the Suzuki cross-coupling of aryl tosylates and arylboronic
acids, Org. Lett. 3 (2001) 3049–3051.
[31] V. Percec, G.M. Golding, J. Smidrkal, O. Weichold, NiCl2(dppe)-catalyzed
cross-coupling of aryl mesylates, arenesulfonates and halides with arylboronic
acids, J. Org. Chem. 69 (2004) 3447–3452.
[32] T. Hatakeyama, T. Hashimoto, Y. Kondo, Y. Fujiwara, H. Seike, H. Takaya, Y. Tamada,
T. Ono, M. Nakamura, Iron-catalyzed Suzuki–Miyaura coupling of alkyl halides,
J. Am. Chem. Soc. 132 (2010) 10674–10676.
[46] N.L. Holy, N.C. Baenziger, R.M. Flynn, D.C. Swenson, The synthesis and structure of
mercuric halide complexes of triphenylphosphonium cyclopentadienylide. The first
x-ray structure of
a mercury cyclopentadienyl, J. Am. Chem. Soc. 98 (1976)
7823–7824.
[47] J. Vicente, M.T. Chicote, M.C. Lagunas, P.G. Jones, Synthesis and structural character-
ization of gold-(I), -(III) and silver(I) complexes of the ylide ligand Ph3P[double
bond, length as m-dash]CHC(O)NMe2. Crystal structure of [(AuPPh3)2{μ-C(PPh3)
C(O)NMe2}]ClO4, J. Chem. Soc. Dalton Trans. 10 (1991) 2579–2583.
[48] S.J. Sabounchei, H. Nemattalab, S. Salehzadeh, M. Bayat, H.R. Khavasi, H.J. Adams,
New mono and binuclear mercury(II) complexes of phosphorus ylides containing
DMSO as ligand: spectral and structural characterization, Organomet. Chem. 693
(2008) 1975–1985.
[49] S.J. Sabounchei, H. Nemattalab, S. Salehzadeh, S. Khani, M. Bayat, H. Adams, M.D.
Ward, Synthesis and characterization of binuclear mercury(II) complexes of phos-
phorus ylides, X-ray analysis and multinuclear NMR measurements, Inorg. Chim.
Acta 362 (2009) 105–112.
[33] M. Tobisu, T. Xu, T. Shimasaki, N. Chatani, Nickel-catalyzed Suzuki–Miyaura reaction
of aryl fluorides, J. Am. Chem. Soc. 133 (2011) 19505–19511.
[34] M.B. Thathagar, J. Beckers, G. Rothenberg, Combinatorial design of copper-based
mixed nanoclusters: new catalysts for Suzuki cross-coupling, Adv. Synth.
Catal. 345 (2003) 979–985.
[35] D.K. Seth, S. Bhattacharya, Copper(I) complexes of N-(aryl)pyridine-2-aldimines:
spectral, electrochemical and catalytic properties, Polyhedron 30 (2011)
2438–2443.
[36] S.J. Sabounchei, M. Ahmadi, Z. Nasri, Five-membered cyclopalladated complex con-
taining bidentate phosphine ligands: synthesis, characterization, and highly efficient
Suzuki cross-coupling reactions, J. Coord. Chem. 66 (2013) 411–423.
[37] S.J. Sabounchei, M. Panahimehr, M. Ahmadi, Z. Nasri, H.R. Khavasi, Four-coordinate
Pd(II) complexes containing non-symmetric phosphorus ylides: synthesis,
characterization, and catalytic behavior towards Suzuki reaction, J. Organomet.
Chem. 723 (2013) 207–213.
[50] S.J. Sabounchei, A. Dadrass, M. Jafarzadeh, S. Salehzadeh, H.R. Khavasi, Synthesis of a
new carbbenzyloxymethylenetriparatolylphosphorane ylide and study of its reac-
tion with mercury(II) halides: spectral and structural characterization, J. Organomet.
Chem. 692 (2007) 2500–2507.
[51] J.C. Slater, Atomic radii in crystals, J. Chem. Phys. 41 (1964) 3199–3204.
[52] K. Karami, C. Rizzoli, M.M. Salah, Synthesis and application of ortho-palladated
complex of (4-phenylbenzoylmethylene)triphenylphosphorane as
a highly
active catalyst in the Suzuki cross-coupling reaction, J. Organomet. Chem. 696
(2011) 940–945.
[53] G.A. Molander, M.R. Rivero, Suzuki cross-coupling reactions of potassium
alkenyltrifluoroborates, Org. Lett. 4 (2002) 107–109.
[54] J.P. Wolfe, R.A. Singer, B.H. Yang, S.L. Buchwald, Highly active palladium catalysts for
Suzuki coupling reactions, J. Am. Chem. Soc. 121 (1999) 9550–9561.
[55] L.-C. Liang, P.-S. Chien, M.-H. Huang, Catalytic Suzuki coupling reactions by amido
phosphine complexes of palladium, Organometallics 24 (2005) 353–357.
[56] R. Gujadhur, D. Venkataraman, J.T. Kintigh, Formation of aryl-nitrogen bonds using a
soluble copper(I) catalyst, Tetrahedron Lett. 42 (2001) 4791–4793.
[57] A.S. Demir, O. Reis, M. Emrullahoglu, Role of copper species in the oxidative dimeriza-
tion of arylboronic acids: synthesis of symmetrical biaryls, J. Org. Chem. 68 (2003)
10130–10134.
[58] J.-H. Li, D.-P. Wang, CuI/DABCO-catalyzed cross-coupling reactions of aryl halides
with arylboronic acids, Eur. J. Org. Chem. 9 (2006) 2063–2066.
[59] J.-H. Li, J.-L. Li, D.-P. Wang, S.-F. Pi, Y.-X. Xie, M.-B. Zhang, X.-C. Hu, CuI-catalyzed
Suzuki–Miyaura and Sonogashira cross-coupling reactions using DABCO as ligand,
J. Org. Chem. 72 (2007) 2053–2057.
[60] J. Liu, F. Dai, Z. Yang, S. Wang, K. Xie, A. Wang, X. Chen, Z. Tan, Synthesis of
1,2-disubstituted acetylenes via copper-catalyzed Suzuki coupling of organoboronic
acids with 1,1-dibromo-1-alkenes, Tetrahedron Lett. 53 (2012) 5678–5683.
[61] J. Zhou, X. Guo, C. Tu, X. Li, H. Sun, Aqueous Suzuki coupling reaction catalyzed by
water-soluble diimine/Pd(II) systems, J. Organomet. Chem. 694 (2009) 697–702.
[62] M. Non-nenmacher, D. Kunz, F. Rominger, T. Oeser, Palladium(II) complexes bearing
methylene and ethylene bridged pyrido-annelated N-heterocyclic carbene ligands
as active catalysts for Heck and Suzuki–Miyaura cross-coupling reactions,
J. Organomet. Chem. 692 (2007) 2554–2563.
[38] S.J. Sabounchei, M. Ahmadi, An efficient protocol for copper- and amine-free
Sonogashira reactions catalyzed by mononuclear palladacycle complexes containing
bidentate phosphine ligands, Catal. Commun. 37 (2013) 114–121.
[39] S.J. Sabounchei, M. Ahmadi, Palladacycle phosphine complexes as homogeneous
catalysts for the Heck cross-coupling reaction at low catalyst loading under aerobic
conditions, Inorg. Chim. Acta 405 (2013) 15–23.
[40] The copper complexes 1–2 were synthesized by the following procedures: To a so-
lution of CuCl (0.5 mmol) in dry methanol (10 ml), a solution of phosphorus ylide
(0.5 mmol) also in dry methanol (10 ml) was added dropwise at 25 °C and stirred
for 4 h. The separated solid was filtered, and recrystallized in dichloromethane. (1):
Yield: 0.564 g (83 %). M.p. 155–158 °C. Anal. Calc. for C66H54Br2Cl2Cu2O2P4: C, 58.25;
H, 4.00. Found: C, 58.48; H, 4.13 %. IR (KBr, cm−1): 1533 (CO). 1H NMR (CDCl3) δH
1
1
(ppm): 3.99 (dd, 2H, CH2, JPH = 12.8 Hz), 4.95 (dd, 1H, PCH, JPH = 17.4 Hz),
7.24–8.05 (m, 24H, Ph). 31P NMR (CDCl3) δp (ppm): -17.72 (br, –PPh21), 20.60 (d,
–PC(H), JP-P = 67.7 Hz). 13C NMR (CDCl3) δC (ppm): 29.63 (dd, CH2, JPC = 63.2
2
1
Hz), 40.93 (dd, CHP, JPC = 92.6 Hz), 124.02–137.96 (Ph), 187.04 (s, CO). (2)
Yield: 0.505 g (80 %). M.p. 156–157 °C. Anal. Calc. for C68H60Cl2Cu2O4P4: C, 64.66;
H, 4.79. Found: C, 64.93; H, 4.95%. IR (KBr, cm−1): 1531 (C = O). 1H NMR (CDCl3)
1
δH (ppm): 4.01 (dd, 2H, CH2, JPH = 12.8 Hz), 3.81 (s, 3H, OCH3), 4.95 (dd, 1H,
1
PCH, JPH = 17.2 Hz), 6.90–8.18 (m, 24H, Ph). 31P NMR (DMSO-d6) δp (ppm):
[63] H. Yang, X. Han, Z. Ma, R. Wang, J. Liu, X. Ji, Palladium-guanidine complex
immobilized on SBA-16: a highly active and recyclable catalyst for Suzuki cou-
pling and alcohol oxidation, Green Chem. 12 (2010) 441–451.
2
-21.42 (br, –PPh2), 23.93 (d, –PC(H), JP-P = 71.0 Hz).13C NMR (CDCl3) δC(ppm):
1
1
30.07 (dd, CH2, JPC = 66.0 Hz), 38.88 (dd, CHP, JPC = 90.8 Hz), 55.31 (s, OCH3),

44
S.J. Sabounchei et al. / Inorganic Chemistry Communications 36 (2013) 39–44
[64] S.R. Chemler, D. Trauner, S.J. Danishefsky, The B-alkyl Suzuki–Miyaura cross-coupling
reaction: development, mechanistic study, and applications in natural product synthe-
sis, Angew. Chem. Int. Ed. 40 (2001) 4544–4568.
[65] J.P. Wolfe, H. Tomori, J.P. Sadighi, J. Yin, S.L. Buchwald, Simple, efficient catalyst sys-
tem for the palladium-catalyzed amination of aryl chlorides, bromides, and triflates,
J. Org. Chem. 65 (2000) 1158–1174.
[66] A.F. Littke, G.C. Fu, A convenient and general method for Pd-catalyzed suzuki
cross-couplings of aryl chlorides and arylboronic acids, Angew. Chem. Int. Ed. 37
(1998) 3387–3388.
[67] A. Zapf, M. Beller, Palladium/phosphite catalyst systems for efficient cross coupling
of aryl bromides and chlorides with phenylboronic acid, Chem. Eur. J. 6 (2000)
1830–1833.
[68] J.-C. Hierso, A. Fihri, R. Amardeil, P. Meunier, H. Doucet, M. Santelli, Use of a bulky
phosphine of weak σ-donicity with palladium as a versatile and highly-active cata-
lytic system: allylation and arylation coupling reactions at 10−1–10−4 mol% catalyst
loadings of ferrocenyl bis(difurylphosphine)/Pd, Tetrahedron 61 (2005) 9759–9766.
[69] T.E. Barder, S.D. Walker, J.R. Martinelli, S.L. Buchwald, Catalysts for Suzuki—Miyaura
coupling processes: scope and studies of the effect of ligand structure, J. Am. Chem.
Soc. 127 (2005) 4685–4696.
[70] K.W. Anderson, S.L. Buchwald, General catalysts for the Suzuki–Miyaura and
Sonogashira coupling reactions of aryl chlorides and for the coupling of challenging
substrate combinations in water, Angew. Chem. Int. Ed. 44 (2005) 6173–6177.
[71] C.J. Rodriguez, D.F. Foster, G.R. Eastham, D.J. Cole-Hamilton, Highly selective forma-
tion of linear esters from terminal and internal alkenes catalysed by palladium com-
plexes of bis-(di-tert-butylphosphinomethyl)benzene, Chem. Commun. 15 (2004)
1720–1721.
[72] J. Hassan, M. Sévignon, C. Gozzi, E. Schulz, M. Lemaire, Metal Unsaturation and Ligand
Hemilability in Suzuki Coupling, Acc. Chem. Res. 40 (2007) 676–684.
[73] B. Punji, J.T. Mague, M.S. Balakrishna, Thioether-functionalized ferrocenyl-
bis(phosphonite), Fe{(C5H4)P(-OC10H6(μ-S)C10H6O-)}2: synthesis, coordination be-
havior and application in Suzuki cross-coupling reactions, Inorg. Chem. 46 (2007)
10268–10275.
[74] B. Karimi, P. Fadavi Akhavan,
A study on applications of N-substituted
main-chain NHC-palladium polymers as recyclable self-supported catalysts for
the Suzuki–Miyaura coupling of Aryl chlorides in water, Inorg. Chem. 50
(2011) 6063–6072.
[75] J. Mao, J. Guo, F. Fang, S.-J. Ji, Highly efficient copper(0)-catalyzed Suzuki–Miyaura
cross-coupling reactions in reusable PEG-400, Tetrahedron 64 (2008) 3905–3911.