Synthesis and structural characterization of dimeric phosphine ylide Cu(I) complexes: Application in Suzuki cross-coupling reactions and biological evaluation as antibacterial agents

Article abstract of DOI:10.1016/j.jorganchem.2014.03.017

In this work we report the synthesis of the complexes of the type [Cu(μ-Cl){Ph₂P(CH₂)_nPPh₂C(H)C(O) PhR}]₂ (n = 1: R = Cl (1), NO₂ (2); n = 2: R = Cl (3), NO₂ (4)) derived from the reactions of the copper(I) chloride with related phosphorus ylides in equimolar ratios using dry methanol as solvent. The identity of complex 1 was unequivocally determined by single crystal X-ray diffraction techniques, its structure consisting of five-membered rings formed by coordination of the ligands through the phosphine group and the ylidic carbon atom to the metal center. The coordination geometry around the Cu atoms in this complex can be defined as slightly distorted tetrahedral. Characterization of the obtained compounds was also performed by IR, ¹H, ³¹P and ¹³C NMR spectroscopy and analytical data indicated a 1:1 stoichiometry between the Cu(I) chloride and ylide. Well-defined phosphine bis-ylide Cu(I) complexes 1 and 3 were found to be an effective catalyst for the Suzuki coupling of various aryl halides including with 4-ethyl phenylboronic acid, giving the desired coupling products at low catalyst loading in moderate to good yields. Also, the antibacterial activities of DMSO-solved complexes were measured by disc diffusion method against 6 Gram positive and negative bacteria. All Cu(I) complexes exhibited antibacterial activities against bacteria tested especially Gram negative ones.

Full text of DOI:10.1016/j.jorganchem.2014.03.017

Journal of Organometallic Chemistry 761 (2014) 111e119
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis and structural characterization of dimeric phosphine ylide
Cu(I) complexes: Application in Suzuki cross-coupling reactions
and biological evaluation as antibacterial agents
,
a
a
a
Seyyed Javad Sabounchei a , Mahbubeh Pourshahbaz , Ali Hashemi , Mohsen Ahmadi ,
*
Roya Karamian b, Mostafa Asadbegy b, Hamid Reza Khavasi c
a Faculty of Chemistry, Bu-Ali Sina University, Hamedan 65174, Iran
b Department of Biology, Faculty of Science, Bu-Ali Sina University, Hamedan 65174, Iran
c Department of Chemistry, Shahid Beheshti University, G.C., Evin, Tehran 1983963113, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
In this work we report the synthesis of the complexes of the type [Cu(m-Cl){Ph2P(CH2)nPPh2C(H)C(O)
Received 8 October 2013
Received in revised form
1 March 2014
PhR}]2 (n ¼ 1: R ¼ Cl (1), NO2 (2); n ¼ 2: R ¼ Cl (3), NO2 (4)) derived from the reactions of the copper(I)
chloride with related phosphorus ylides in equimolar ratios using dry methanol as solvent. The identity
of complex 1 was unequivocally determined by single crystal X-ray diffraction techniques, its structure
consisting of five-membered rings formed by coordination of the ligands through the phosphine group
and the ylidic carbon atom to the metal center. The coordination geometry around the Cu atoms in this
complex can be defined as slightly distorted tetrahedral. Characterization of the obtained compounds
was also performed by IR, 1H, 31P and 13C NMR spectroscopy and analytical data indicated a 1:1 stoi-
chiometry between the Cu(I) chloride and ylide. Well-defined phosphine bis-ylide Cu(I) complexes 1 and
3 were found to be an effective catalyst for the Suzuki coupling of various aryl halides including with 4-
ethyl phenylboronic acid, giving the desired coupling products at low catalyst loading in moderate to
good yields. Also, the antibacterial activities of DMSO-solved complexes were measured by disc diffusion
method against 6 Gram positive and negative bacteria. All Cu(I) complexes exhibited antibacterial ac-
tivities against bacteria tested especially Gram negative ones.
Accepted 19 March 2014
Keywords:
Cu(I) complex
Phosphorus ylide
Crystal structure
Suzuki cross-coupling
Low catalyst loading
Antibacterial agent
Ó 2014 Published by Elsevier B.V.
Introduction
Schmidbaur reported Cu(I) complexes of phosphorus ylides of the
type (C6H5)3PCHR (R ¼ H, CH3, CH(CH3)2) [20]. In this work, we
Phosphorus ylides are important reagents in organic chemistry,
especially in the synthesis of naturally occurring products with
biological and pharmacological activities [1]. These compounds
have been used as reducing agents in coordination chemistry. The
utility of metalated phosphorus ylides in synthetic chemistry has
have now focused our attention in the study of the coordination
mode adopted by the resonance stabilized ylides when ligated to
Cu(I) (Scheme 1).
The results of these studies including the full characterization of
the obtained complexes (performed by elemental analysis, IR,
multinuclear NMR techniques and electrochemical data) are also
presented and discussed in this study. By a comparison of the data
collected and single crystal X-ray diffraction of 1, it demonstrates P,
C-coordination of the ylide to the metal.
Recently, the application of copper complexes as catalyst in CeC
coupling reactions and use as antibacterial agents has been
attracting considerable attention [21e28]. The discovery of cross-
coupling reaction is one of the most striking breakthrough in
organic chemistry and it has brought a lot of benefits: (i) it has
expanded the scope for what we can synthesize and (ii) it has
changed the methodology for the retrosynthesis, enabling us to
shorten the synthetic procedures. Transition metal-catalyzed CeC
been well documented [2e7]. The a-ketostabilized ylides derived
from bisphosphines, viz., Ph2PCH2ePPh2]C(H)C(O)R and
Ph2PCH2CH2PPh2]C(H)C(O)R (R ¼ 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 be engaged in different kinds of
bonding with metal ions [8e19]. P, C-coordination mode of stabi-
lized phosphorus ylides have been previously observed for Pd(II),
Pt(II), Rh(I), Hg(II) species [8e18]. In 1975 Yamamoto and
* Corresponding author.
E-mail address: jsabounchei@yahoo.co.uk (S.J. Sabounchei).
http://dx.doi.org/10.1016/j.jorganchem.2014.03.017
0022-328X/Ó 2014 Published by Elsevier B.V.

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S.J. Sabounchei et al. / Journal of Organometallic Chemistry 761 (2014) 111e119
Scheme 1. Reaction of ylides with CuCl.
bond forming reactions are powerful synthetic tools in organic
chemistry [29]. The Suzuki reaction, a cross-coupling process in
which an organoboron reagent is reacted with an aryl halide (or
pseudohalide), has become a successful method of forming CeC
bonds [30]. The original and general Suzuki coupling procedures
involves the use of phosphine palladium complexes as catalysts
[31]. Currently, researchers around the world show interest in using
copper as an alternative of Pd in coupling reactions, because Pd is a
precious metal and the reserve is much less than Cu, so it will cost
more to use Pd. For these reasons, the copper-catalyzed Suzuki
cross-coupling reaction has received a lot of attention in the past
few years and has already been reviewed [21e24,32]. Very recently,
Gurung and coworkers published an article about the copper-
catalyzed Suzuki-Miyaura coupling of arylboronate esters and
demonstrated that in-situ generated copper complex exhibits
efficient activity toward aryl iodides [24]. The above-mentioned
findings prompted us to study whether the Suzuki cross-coupling
reaction could directly be catalyzed by more accessible copper
catalyst. Our previous research showed that symmetrical and non-
symmetrical phosphorus ylides are versatile ligands and their
palladium complexes are quite efficient cross-coupling catalysts
[33]. Excellent activities observed with Pd(II) complexes of phos-
phine ylide ligands encouraged us to explore the chemistry of
copper complexes.
As copper is well known for its biological activities [34e39], we
paid attention to the antibacterial properties of these complexes.
Indeed antibacterial resistance is becoming a global concern with a
rapid development of multidrug resistances [40]. In the present
work, we have focused our attention in the study of the coordina-
tion modes adopted by the resonance stabilized ylides when ligated
to Cu(I) (Scheme 1). Secondly, we have worked on catalytic activity
of the new copper (I) phosphine ylide complexes 1 and 3 in Suzuki
cross-coupling reactions. Finally we explored the antibacterial ac-
tivities of ligands Y1eY4 and complexes 1e4.
Preparation of [CuCl(Ph2PCH2PPh2C(H)C(O)C6H4Cl]2 (1)
To a solution of CuCl (0.049 g, 0.5 mmol) in dry methanol
(10 ml), a solution of Y1 (0.268 g, 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 dichloro-
methane. Anal. Calc. for C66H54Cl4Cu2O2P4: C, 62.32; H, 4.28.
Found: C, 62.43; H, 4.33%. Yield: 0.515 g (81%). M.p. 156e158 ꢀC. IR
absorption in KBr (cmꢁ1) 1542 (
n
C]O). 1H NMR (CDCl3) dH (ppm):
1
3.92 (dd, 2H, CH2, JPH ¼ 12.85, 12.84 Hz); 4.95 (d, 1H, PCH,
1JPH ¼ 17.41); 7.24e8.11 (m, 24H, Ph). 31P NMR (DMSO-d6) dP
(ppm): ꢁ22.24 (br, P); 22.55 (d, P^y, JPP ¼ 63.93 Hz). 13C NMR
2
1
(CDCl3) dC (ppm): 29.63 (dd, CH2, JPC ¼ 63.56, 63.09 Hz), 40.89
1
(dd, CHP, JPC ¼ 93.80, 97.67 Hz), 124.09e137.59 (Ph), 186.89
(s, CO).
Preparation of [CuCl(Ph2PCH2PPh2C(H)C(O)C6H4NO2]2 (2)
Complex 2 was prepared following the same method used for 1.
Thus, CuCl (0.049 g, 0.5 mmol) was reacted with ylide
Ph2PCH2PPh2C(H)C(O)C6H4NO2 (Y2) (0.273 g, 0.5 mmol) giving 2.
Anal. Calc. for C66H54Cl2Cu2N2O6P4: C, 61.31; H, 4.21; N, 2.17. Found:
C, 61.53; H, 4.36; N, 2.23%. Yield 0.497 g (77%). M.p. 165e167 ꢀC. IR
absorption in KBr (cmꢁ1) 1555 ( C]O). 1H NMR (DMSO-d6) dH
n
(ppm): 4.33 (br, 2H, CH2); 5.19 (d, 1H, PCH, 1JPH ¼ 15.82 HZ); 7.35e
8.20 (m, 24H, Ph). 31P NMR (DMSO-d6) dP (ppm): ꢁ20.40 (br, P);
22.20 (d, P^y, 2JPP ¼ 67.08).
Preparation of [CuCl(Ph2P(CH2)2PPh2C(H)C(O)C6H4Cl)]2 (3)
To a solution of CuCl (0.049 g, 0.5 mmol) in dry methanol
(10 ml), a solution of Y3 (0.275 g, 0.5 mmol) also in dry methanol
(10 ml) was added dropwise at 25 ꢀC and stirred for 7 h and then
concentrated to ca. 2 ml in volume and treated with n-hexane
(ca. 15 ml) to afford a yellow solid. Anal. Calc. for C68H58Cl4Cu2O2P4:
C, 62.83; H, 4.50. Found: C, 62.94; H, 4.71. Yield 0.506 g (78%). M.p.
>126 ꢀC (decomposes). IR absorption in KBr (cmꢁ1) 1516 ( C]O). 1H
n
Experimental
NMR (CDCl3) dH (ppm): 2.54 (br, 2H, CH2); 3.09 (br, 2H, CH2); 4.22
(br, 1H, PCH); 7.28e7.95 (m, 24H, Ph). 31P NMR (CDCl3) dP
(ppm): ꢁ10.26 (br. d, P); 15.40 (br. d, P^y). 13C NMR (CDCl3) dC (ppm):
29.59 (br, CH2), 124.09e139.42 (Ph), 186.89 (s, CO)(CH was not been
seen).
The starting materials were purchased from commercial sources
and used without further purification. Melting points were
measured on a SMPI apparatus. Elemental analyses for C, H and N
atoms were performed using a PerkineElmer 2400 series analyzer.
IR spectra were recorded on a Shimadzu 435-U-04 spectropho-
tometer from KBr pellets. 1H, 31P and 13C NMR spectra were recor-
ded on 300 MHz Bruker and 90 MHz Jeol spectrometer in DMSO-d6
or CDCl3 as solvent at 25 ꢀC. Chemical shifts (ppm) are reported
according to internal TMS and external 85% phosphoric acid.
Preparation of [CuCl(Ph2P(CH2)2PPh2C(H)C(O)C6H4NO2]2 (4)
Complex 4 was prepared following the same method used for 3.
Thus, CuCl (0.049 g, 0.5 mmol) was reacted with ylide
Ph2P(CH2)2PPh2C(H)C(O)C6H4NO2 (Y4) (0.280 g, 0.5 mmol) giving 4.
Anal. Calc. for C68H58Cl2Cu2N2O6P4: C, 61.82; H, 4.43; N, 2.12.
Found: C, 61.92; H, 4.61; N, 2.23%. Yield 0.495 g (75%). M.p. >129 ꢀC
Preparation of ligands
(decomposes). IR absorption in KBr (cmꢁ1) 1528 ( C]O). 1H NMR
n
The ligands [Ph2P(CH2)nPPh2C(H)C(O)C6H4R] (Y1eY2: n ¼ 1,
R ¼ Cl, NO2 and Y3eY4: n ¼ 2, R ¼ Cl, NO2) were prepared based on
the published methods (Supplementary material) [41e44].
(CDCl3) dH (ppm): 2.50 (br, 2H, CH2); 3.16 (br, 2H, CH2); 4.20 (br, 1H,
CH); 7.19e8.08 (m, 24H, Ph). 31P NMR (CDCl3) dP (ppm): ꢁ11.79
3
(br, P); 15.24 (d, P^y, JPP ¼ 50.04 Hz).

S.J. Sabounchei et al. / Journal of Organometallic Chemistry 761 (2014) 111e119
113
X-ray crystallography
Spectroscopy
The single crystal X-ray diffraction data of suitable crystals of 1
The nCO, which is sensitive to complexation, occurs around
1500 cmꢁ1 in the parent ylides [49]. Coordination of the ylide
through carbon causes an increase in the nCO, while, when O-co-
ordination occurs, a lowering in the value of the nCO would be ex-
pected [50e52]. Thus the IR absorption bands for the complexes at
higher frequencies indicate that C-coordination has occurred [15].
The 31P chemical shift values for the complexes appear to be
shifted downfield with respect to the parent ylide, also indicating
that coordination of the ylide has occurred. In the 31P NMR spectra
the signal due to phosphonium group (P^y) appears as doublet at
22.55 (2JPP ¼ 63.93 Hz) and 22.20 (2JPP ¼ 67.08 Hz) ppm for 1 and 2,
respectively. The significant downfield shift of this signal from that
of the free ylide (Y1 11.35 (2JPP ¼ 63.82 Hz) and Y2 11.52
(2JPP ¼ 65.63 Hz) ppm, respectively) is in agreement with the C-
bonding of the ylides [15]. The coordination via the phosphine
moiety is also clearly evidenced from the strong downfield shifts of
the signal due to the PPh2 group (P) at ꢁ22.24 (br) and ꢁ20.40 (br)
ppm for 1 and 2, respectively, when compared to that of same
signal in the free ylides (Y1 ꢁ29.90 (2JPP ¼ 64.00 Hz) and Y2 ꢁ30.31
(2JPP ¼ 62.47 Hz) ppm, respectively) [15]. The identical pattern in
chemical shift values in the 31P NMR spectra of complexes 3 and 4
suggest similar structures with complexes 1 and 2. The P, C-
chelating of ligands Y1eY4 has been previously observed for mer-
cury halide and palladium complexes [41e43]. The downfield shift
and broadening of the doublet signal was observed due to the ylidic
proton in the 1H NMR spectra of complexes 1 and 2 [41]. Similar
behavior was observed earlier in the case of ylide complexes of
platinum(II) chloride [53]. In the case of complexes 3 and 4 this
signals are weak and very broad due to low solubility. The expected
lower shielding of 31P and 1H nuclei for the PC(H) group (P^y) upon
complexation in the case of C-coordination were observed in their
corresponding spectra. The upfield shift of the signals due to ylidic
carbons in the 13C NMR spectra of complexes 1 is also an evidence
was collected on a STOE IPDS-II diffractometer at 298 K, using
ꢀ
graphite monochromated Mo K
collection was performed using the
a
radiation (
u
l
¼ 0.71073 A). The data
-scan technique and using the
STOE X-AREA software package [45], while data reduction was
carried out using the program X-RED31. The crystal structures were
solved by direct methods and refined by full-matrix least-squares
on F2 using the programs SHELX and SHELXL respectively [46] and
using the X-STEP32 crystallographic software package [47]. The H
atoms were included in calculated positions and treated as riding
atoms using SHELXL [48] default parameters. Numerical absorption
corrections was applied for 1.
General procedure for Suzuki cross-coupling reactions
In a typical run, a 25 ml Schlenk tube was charged with a
mixture of an aryl halide (0.5 mmol), 4-ethyl phenylboronic acid
(0.75 mmol), catalyst (5 mol%), Cs2CO3 (1.5 mmol) and DMF (2 ml)
under nitrogen. The tube was placed in a 130 ꢀC oil bath and stirred
for 24 h. The reaction progress was monitored by thin-layer chro-
matography (TLC). The reaction mixture was then cooled to room
temperature and then 15 ml water was added, followed by
extraction with n-hexane (15 ml) The combined organic layer were
washed with brine (3 ꢂ 15 ml) and dried over CaCl2. The solvent
was evaporated and a crude product was obtained. The purified
products were identified by comparison of their 1H and 13C NMR
spectral data with the literature [33]. Yields were calculated against
consumption of the aryl halides.
Antibacterial activity
The potential antibacterial effects of the copper complexes were
investigated by disc diffusion method against 3 Gram positive
bacteria, namely Bacillus cereus (PTCC 1247), Staphylococcus aureus
(Wild), Bacillus megaterium (PTCC 1017), and 3 Gram negative
bacteria, namely Escherichia coli (Wild), Proteus vulgaris (PTCC
1079), and Serratia marcescens (PTCC 1111) [48]. The metal com-
plexes were dissolved in DMSO to a final concentration of 1 mg/ml
for C-coordination [54]. Such an upfield shift observed in [PdCl (h3
-
2-XC3H4) (C6H5)3PCHCOR] (X ¼ H, CH3; R ¼ CH3, C6H5) was
attributed to the change in hybridization of the ylidic carbon [41].
Similar upfield shifts of 2e3 ppm with reference to the parent ylide
were also observed in the case of [(C6H5)3PC5H4HgI2]2 [54]. The 13
C
NMR shift of the CO signal (w180ew187 ppm) with reference to
the parent ylide indicates a much lower shielding of the carbon of
the CO group in this complex. Because of the low solubility of the
complexes 2 and 4 it was not possible to get 13C NMR of these
compounds. Neither HeCu nor PeCu coupling was observed at
and then sterilized by filtration using 0.45 mm Millipore. All tests
were carried using 10 ml of suspension containing
1.5 ꢂ 108 bacteria/ml and spread on nutrient agar medium. Nega-
tive controls were prepared by using DMSO. Cephalexin was used
as positive reference standards. The diameters of inhibition zones
generated by the complexes were measured.
Statistical analysis
All data, for both antibacterial tests, are the average of triplicate
analysis. Analysis of variance was performed by Excel and SPSS
procedures. Statistical analysis was performed using student’s t-
test and P value <0.05 was regarded as significant.
Results and discussion
Synthesis
The reaction of CuCl with the ligands in methanol (1:1) at room
temperature yielded the binuclear complexes (see Scheme 1). X-ray
structure of complexes 1 demonstrate the five-membered chelate
ring in which the ligands were chelated to the metals through the
free phosphine group and the ylidic carbon atom.
Fig. 1. X-ray crystal structure of 1. Hydrogen atoms are omitted for clarity.

114
S.J. Sabounchei et al. / Journal of Organometallic Chemistry 761 (2014) 111e119
Table 2
room temperature in the spectra. Failure to observe NMR coupling
and broading in the above spectra is probably due to mainly the
quadrupolar moment of Cu63 or Cu65 [55,56].
ꢀ
ꢀ
Selected bond distances (A) and angles ( ) for 1.
Bond distances
Bond angles
C(26)eCu(1)
P(1)eCu(1)
C(26)eC(27)
C(27)eO(1)
C(26)eP(2)
Cu(1)eCl(1)
Cu(1)eCl(1)#1
2.295(5)
2.1994(16)
1.432(7)
1.250(7)
1.741(6)
Cl(1)eCu(1)eC(26)
Cl(1)#1eCu(1)eC(26)
P(1)eCu(1)eC(26)
Cl(1)eCu(1)eCl(1)#1
P(1)eCu(1)eCl(1)
97.26(5)
115.67(13)
96.04(14)
97.26(5)
124.10(5)
119.69(6)
82.74(4)
X-ray crystallography
Complex 1 was recrystallized by slow evaporation over several
days from chloroform solutions. The molecular structure is shown
in Fig. 1. Relevant parameters concerning data collection and
refinement are given in Table 1 and selected bond distances and
angles are collected in Table 2. Crystallographic data for the struc-
ture in this paper can be found in the Supplementary material. The
complex consists of centrosymmetrical dimeric units with the two
chlorine atoms bridging the two copper atoms. The tetrahedral
coordination of the copper atoms is achieved by P, C chelating of the
ylide. Two ylidic ligands are respectively located on the opposite
sides to minimize the repulsion between them. The angles sub-
tended by the ligand at the Cu(I) center in 1 vary from 96.04ꢀ to
124.10ꢀ indicating a distorted tetrahedral environment. The CueP
2.3560(12)
2.3577(15)
P(1)eCu(1)eCl(1)#1
Cu(1)eCl(1)eCu(1)#1
anions and copper atoms, forming a four-membered ring. Both
copper atoms are also linked by the halide anions so that the cores
of the complexes are approximate (square planar parallelogram)
with Cu/Cu and X/X diagonals. The crystal packing of the com-
plex 1 (Fig. 3) is stabilized by intermolecular CeH/Cl and C]
O/HeC interactions (see Supplementary material Table S9).
ꢀ
bond lengths (w2.199 A) are in the usual range for similar Cu(I)
Suzuki cross-coupling reaction of aryl halides
complexes such as [Cu2(
m
-Cl)2(
k
2-P,P-dppf)2] (2.275(1) and
ꢀ
ꢀ
2.270(1) A) [57], [Cu(
[(PeN)Cu(
m
-I)(dppf)]2 (2.265(7) and 2.270(7) A) [58] and
To test the catalytic activity of Cu(I) complexes in the Suzuki
reaction, the reaction between iodobenzene and 4-ethyl phenyl-
boronic acid in presence of Cat. 1 and Cat. 3 (Scheme 2) was chosen
as model reaction. Influences of different parameters were exam-
ined to obtain the best possible combination. The parameters
included solvent, base, reaction temperature and catalyst
concentration.
ꢀ
m
-Br)2Cu(PeN)] (2.201(9) A) [59] (Fig. 2). The Cu/Cu
ꢀ
distance of 3.115 (1) A is longer than the sum of Van der Waals radii
ꢀ
for the two copper atoms (2.8 A) [60] indicating the absence of
significant bonding interactions between the Cu atoms in the mo-
lecular structures. The CueCl bond lengths 2.356 (12) and 2.358
(15) indicating an asymmetric halide bridge are in agreement to
those found in the dimeric complex, [Cu2(
m
-Cl)2(
k
2-P,P-dppf)2]
ꢀ
As shown in Table 3, the coupling reaction yields were suscep-
tible to temperature changes in the presence of 5 mol% catalyst and
DMF as solvent (Table 3, entries 3, 10 and 11). The increase of re-
action temperature up to 130 ꢀC led to good yields 81% (Table 3,
entry 3, Cat. 1) and 90% (Table 3, entry 3, Cat. 3). During the opti-
mization process, it was found that the best yields were obtained
after 24 h in the presence of 5 mol% of catalyst at 130 ꢀC (Table 3,
entry 3). Using a larger amount of catalyst was not found to be
beneficial (Table 3, entry 6). Lowering the catalyst load was found to
be highly detrimental (Table 3, entries 8 and 9). We then examined
the effect of bases and among the tested bases, Cs2CO3 was the most
effective base for the coupled product in presence of Cat. 1 and Cat.
3 (Table 3, entry 3), while other bases, such as NaOAc, K2CO3 and
Na2CO3 gave yields of 56%, 62%, 61% for Cat. 1 and 70%, 76%, 73% for
Cat. 3, respectively (Table 3, entries 1, 2 and 4). Replacement of
these bases by a tertiary amine such as Et3N afforded low product
yields (Table 3, entry 5). The next step was to optimize the condi-
tions to select the best solvent from the commonly used ones.
Notably, solvents were found to have significant effect on catalyst
where the two CueCl bond distances are at (2.358 (1) A and 2.434
ꢀ
(1) A), respectively [57]. The feature of the title this complex is a
double ring structure: the outer ring consists of a CuY1 five-
membered ring, while the inner ring consists of the two halide
Table 1
Crystal data and structure refinement.
Compound
1
Empirical formula
Formula weight
T (K)
C66H54Cl4Cu2O2P4, 4 (CHCl3)
1749.34
120(2)
0.71073
Trigonal
R-3
ꢀ
Wavelength (A)
Crystal system
Space group
Unit cell dimensions
ꢀ
a (A)
33.738(5)
33.738(5)
16.897(3)
90.00
90.00
120.00
16,656(5)
ꢀ
b (A)
ꢀ
c (A)
a
b
g
(ꢀ)
(ꢀ)
(ꢀ)
3
ꢀ
V (A )
Z
9
Calculated density(mg/m3)
Absorption coefficient (mmꢁ1
F (0 0 0)
1.570
1.284
7956
)
Crystal size (mm)
q
0.48 ꢂ 0.49 ꢂ 0.50
Range for data collection (ꢀ)
2.41e26.00
Limiting indices
ꢁ41 ꢃ h ꢃ 41,
ꢁ23 ꢃ k ꢃ 41,
ꢁ20 ꢃ l ꢃ 19
13,654/7267, [Rint ¼ 0.039]
Numerical
Reflections collected/unique
Absorption correction
Maximum and minimum transmission
Refinement method
0.650 and 0.560
Full-matrix least-squares on F2
6793/0/388
0.961
Data/restraints/parameters
Goodness-of-fit (GOF) on F2
Final R indices [I > 2
R indices (all data)
Largest difference in peak and hole (e A
s
(I)]
R1 ¼ 0.0646, wR2 ¼ 0.1820
R1 ¼ 0.0685, wR2 ¼ 0.1724
ꢁ2.44 and 2.98
ꢀꢁ3
)
Fig. 2. Important bond lengths and bond angles for 1.

S.J. Sabounchei et al. / Journal of Organometallic Chemistry 761 (2014) 111e119
115
Table 3
Optimization of the reaction conditions.a
Entry Catalyst (mol%) Solvent
Base
Temp. (ꢀC) Yield (%)b
1(61%), 3(73%)
1
2
5
5
DMF
DMF
Na2CO3 130
K2CO3
Cs2CO3
NaOAc
Et3N
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
130
130
130
130
130
130
130
130
80
1(62%), 3(76%)
1(81%), 3(90%)
1(56%), 3(70%)
1(24%), 3(37%)
1(83%), 3(91%)
1(35%), 3(52%)
1(10%), 3(16%)
Trace
1(45%), 3(60%)
1(68%), 3(83%)
1(72%), 3(80%)
1(67%), 3(76%)
1(45%), 3(58%)
1(34%), 3(49%)
Trace
3
5
DMF
4
5
DMF
5
5
DMF
6
7
10
1
DMF
DMF
8
0.1
DMF
9
0.01
5
5
5
5
5
5
5
DMF
DMF
DMF
10
11
11
12
13
14
15
100
80
100
75
Dioxane
Toluene
Ethanol
Methanol Cs2CO3
H2O Cs2CO3
65
100
a
Reaction condition: iodobenzene (0.5 mmol), 4-ethyl phenylboronic acid
(0.75 mmol), base (1.0 mmol), solvent (2 ml), Cu(I) catalysts (0.01e10 mol%), and
60e130 ꢀC, under N2.
Fig. 3. A representation of part of the unit cell contents of 1. Intermolecular CeH/Cl
and C]O/HeC interactions are shown. Different colors show adjacent molecules. (For
interpretation of the references to color in this figure legend, the reader is referred to
the web version of this article.)
b
Isolated yield.
couplings of aryl chlorides were studied. For activated chloride such
as 40-chloroacetophenone, the yield could be reached 48% (Table 4,
entry 11, Cat. 1) and 61% (Table 4, entry 11, Cat. 3) (Table 4, entry 11).
In the case of chlorotoluene and chlorobenzene, the yield was
decreased to 38% (Table 4, entry 10, Cat. 1), 53% (Table 4, entry 10,
Cat. 3) and 39% (Table 4, entry 9, Cat.1), 55% (Table 4, entry 9, Cat. 3),
respectively.
The observed catalytic activity of Cat. 1 and Cat. 3, though not
remarkably high, are found to be comparable to those found in the
literature for similar Cu(I) catalyzed Suzuki coupling reactions [21e
24,32]. Cat. 3 is more efficient than Cat. 1. This might arise from the
steric hindrance of the six membered ring in Cat. 3 compared with
the five-membered ring in Cat. 1. Table 5 shows a comparison be-
tween the catalytic efficiencies of our catalytic systems and data
from the literature. It evidences that our original catalysts achieve
interesting activities at percent amount of catalyst loading.
activity. Aprotic polar or nonpolar solvents such as N,N-dime-
thylformamide (DMF), dioxane and toluene were found to be more
active than the other protic solvents, such as ethanol, methanol and
water (Table 3, entries 3 and 11e15). DMF was identified as the best
solvent for the reaction (Table 4, entry 3, 81% for Cat. 1 and 90% for
Cat. 3).
Under the optimized reaction conditions, the scope of the re-
action was explored with various aryl halides and 4-ethyl phenyl-
boronic acid. As shown in Table 4, the coupling of aryl bromides
proceeded smoothly at 130 ꢀC and the corresponding products
were obtained in high yields (entries 1e8). In the following ex-
periments, the Suzuki coupling of a variety of electronically and
structurally diverse aryl halides (electron-donating and electron-
withdrawing substitutes) was investigated under the same reac-
tion conditions (see Table 4). As expected, (i) high yields were
achieved from electron deficient aryl bromides (Table 4, entries 3e
6); and (ii) only moderate to good yields were achieved from
electron rich aryl bromides (Table 4, entries 2 and 7).
Antibacterial activity
Results from antibacterial assessment of the samples are pre-
sented in Table 6 and Fig. 4. In general, copper complexes show
antibacterial activity against both of Gram positive and negative
bacteria, with a slightly higher effect on Gram negative ones
[34,61]. According to our results, free ligands, copper atoms (Cu(I)
and Cu(II)) and also metal complexes represented activity espe-
cially on Gram negative bacteria (Table 6). The metal complexes
exhibited activities only slightly higher than the free ligands and
copper (Table 6 and Fig. 4). Although S. aureus (þ) and S. marcescens
(ꢁ) are resistant to cephalexin, the effects of metal complexes were
higher than this antibiotic (Fig. 4). However, further studies are
needed to evaluate the in vivo potential of these compounds in
animal models.
Interestingly, reactions of aryl iodides such as iodobenzene and
iodotoluene gave higher yields than other aryl halides. The yields
achieved with iodobenzene were 81% (Table 4, entry 12, Cat. 1) and
91% (Table 4, entry 12, Cat. 3). Unlike cross coupling reactions
involving aryl bromides (Table 4, entries 1e8), the electron
donating group on aryl iodides did not affect significantly on the
yields variations and the coupling reactions of iodotoluene gave
high yields (Table 4, entry 13, Cat. 1 and Cat. 3). Finally, the
Cl
Cl
O
O
Ph
Ph
Ph
Cl
Conclusion
Cl
P
Ph
P
Cu
Ph
Cu
The present study describes the synthesis and characterization
of new 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. Also, the results reported in this paper are the
examples of practical and easily available phosphine bis-ylide Cu(I)
complexes that can catalyze the Suzuki coupling of aryl halides
P
2
P
2
Ph
Ph
Ph
Cat. 1
Cat. 3
Scheme 2. Cu (I) catalyst precursors 1 and 3.

116
S.J. Sabounchei et al. / Journal of Organometallic Chemistry 761 (2014) 111e119
Table 4
The Suzuki reaction of aryl halides with 4-ethyl phenylboronic acid using catalysts 1 and 3.a
Entry
1
Aryl halides
Productsb
Yield (%)c
1(54%), 3(76%)
2
3
1(52%), 3(73%)
1(58%), 3(79%)
4
5
1(61%), 3(81%)
1(65%), 3(83%)
6
7
1(62%), 3(83%)
1(57%), 3(75%)
8
1(49%), 3(70%)
9
1(39%), 3(55%)
1(38%), 3(53%)
10
11
1(48%), 3(61%)

S.J. Sabounchei et al. / Journal of Organometallic Chemistry 761 (2014) 111e119
117
Table 4 (continued )
Entry
Aryl halides
Productsb
Yield (%)c
12
1(81%), 3(91%)
1(80%), 3(89%)
13
a
Reaction conditions: aryl halide (0.5 mmol), 4-ethyl phenylboronic acid (0.75 mmol), Cs2CO3 (1.5 mmol), DMF (2 ml), catalyst (5 mol%), 130 ꢀC, 24 h, under N2.
Products were identified by comparison of their 1H and 13C NMR spectral data those reported in the literature (see Ref. [33]).
Isolated yield.
b
c
Table 5
Compression with other catalytic system catalyzed with Cu(I) complexes.
Entry
Aryl halide
R2
[Cu] catalyst
mol%
Conditions
Yield (%)
Ref.
1
2
3
4
5
6
7
p-MeePheI
p-OHCePheBr
p-O2NePheBr
p-IePheI
PheBr
PheI
PheBr
p-MeePheI
PheBr
p-MeePheI
H
H
H
H
H
H
Et
Cu colloid
2
5
K2CO3, DMF, 110 ꢀC, 8 h
Cs2CO3, PEG,a 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
54
80
76
89
[32f]
[21]
[23]
[22]
[32g]
[32g]
This work
[{Cu(N-(aryl)pyridine-2-aldimines)I}2]
CuI/DABCOb
10
10
10
10
5
CuI/DABCO/TBABc
Cu powder/I2
Cu powder
[Cu(
[Cu(
m
m
-Cl){Ph2PCH2 Ph2C(H)C(O)PhBr}]2
8
Et
-Cl){Ph2PCH2CH2PPh2C(H)C(O)PhBr}]2
5
Cs2CO3, DMF, 130 ꢀC, 24 h
This work
a
Polyethyleneglycol.
1,4-Diaza-bicyclo[2.2.2]octane.
n-Bu4NBr.
b
c
Table 6
Antibacterial activities of ligands (Y1eY4) and complexes (1e4).
Compounds
Ligand Y1
Ligand Y2
Ligand Y3
Ligand Y4
Complex 1
Complex 2
Complex 3
Complex 4
Concentration
Inhibition zone (mm)
P. vulgaris (ꢁ)
E. coli (ꢁ)
B. cereus (þ)
S. aureus (þ)
B. megaterium (þ)
S. marcescens (ꢁ)
1 (mg/ml)
13 ꢄ 0.42a
10 ꢄ 0.24b
7 ꢄ 0.00c
10 ꢄ 0.16a
8 ꢄ 0.15b
Na
10 ꢄ 0.18a
8 ꢄ 0.15b
Na
8 ꢄ 0.00
10 ꢄ 0.11a
7 ꢄ 0.18b
Na
11 ꢄ 0.33a
8 ꢄ 0.28b
7 ꢄ 0.24c
8 ꢄ 0.22a
7 ꢄ 0.15b
Na
14 ꢄ 0.54a
10 ꢄ 0.14b
7 ꢄ 0.28c
13 ꢄ 0.66a
11 ꢄ 0.27b
7 ꢄ 0.10c
14 ꢄ 0.46a
10 ꢄ 0.11b
8 ꢄ 0.22c
11 ꢄ 0.26a
9 ꢄ 0.27b
Na
0.1 (mg/ml)
0.01 (mg/ml)
1 (mg/ml)
0.1 (mg/ml)
0.01 (mg/ml)
1 (mg/ml)
0.01 (mg/ml)
0.01 (mg/ml)
1 (mg/ml)
0.1 (mg/ml)
0.01 (mg/ml)
1 (mg/ml)
0.1 (mg/ml)
0.01 (mg/ml)
1 (mg/ml)
0.1 (mg/ml)
0.01 (mg/ml)
1 (mg/ml)
0.1 (mg/ml)
0.01 (mg/ml)
1 (mg/ml)
0.1 (mg/ml)
0.01 (mg/ml)
Na
Na
7 ꢄ 0.11
8 ꢄ 0.15a
7 ꢄ 0.25b
Na
9 ꢄ 0.34a
7 ꢄ 0.16b
Na
Na
Na
12 ꢄ 0.42a
11 ꢄ 0.24b
8 ꢄ 0.00c
10 ꢄ 0.96a
9 ꢄ 0.28b
Na
8 ꢄ 0.45a
8 ꢄ 0.33a
Na
8 ꢄ 0.26a
7 ꢄ 0.00b
Na
7 ꢄ 0.25
8 ꢄ 0.13a
7 ꢄ 0.28b
Na
Na
Na
Na
Na
Na
8 ꢄ 0.58a
9 ꢄ 0.24a
7 ꢄ 0.00b
Na
7 ꢄ 0.00a
7 ꢄ 0.15a
Na
Na
Na
15 ꢄ 0.25a
14 ꢄ 0.13b
9 ꢄ 0.16c
16 ꢄ 0.16a
14 ꢄ 0.24b
9 ꢄ 0.11c
16 ꢄ 0.12a
13 ꢄ 0.14b
9 ꢄ 0.45c
15 ꢄ 0.33a
11 ꢄ 0.14b
8 ꢄ 0.25c
15 ꢄ 0.14a
13 ꢄ 0.22b
11 ꢄ 0.17c
15 ꢄ 0.33a
14 ꢄ 0.25b
9 ꢄ 0.00c
14 ꢄ 0.18a
12 ꢄ 0.35b
10 ꢄ 0.15c
15 ꢄ 0.24a
12 ꢄ 0.11b
9 ꢄ 0.18c
13 ꢄ 0.27a
10 ꢄ 0.22b
8 ꢄ 0.12c
12 ꢄ 0.56a
10 ꢄ 0.45b
7 ꢄ 0.34c
13 ꢄ 0.17a
9 ꢄ 0.15b
7 ꢄ 0.33c
11 ꢄ 0.26a
8 ꢄ 0.35b
7 ꢄ 0.00c
18 ꢄ 0.25a
15 ꢄ 0.24b
12 ꢄ 0.34c
17 ꢄ 0.25a
13 ꢄ 0.10b
8 ꢄ 0.14c
17 ꢄ 0.34a
14 ꢄ 0.11b
10 ꢄ 0.11c
17 ꢄ 0.33a
13 ꢄ 0.13b
10 ꢄ 0.00c
12 ꢄ 0.15a
8 ꢄ 0.14b
7 ꢄ 0.00c
11 ꢄ 0.64a
8 ꢄ 0.26b
Na
14 ꢄ 0.18a
11 ꢄ 0.23b
7 ꢄ 0.10c
14 ꢄ 0.24a
10 ꢄ 0.21b
8 ꢄ 0.15c
13 ꢄ 0.28a
10 ꢄ 0.13b
7 ꢄ 0.15c
14 ꢄ 0.34a
11 ꢄ 0.21b
7 ꢄ 0.00c
11 ꢄ 0.13a
9 ꢄ 0.16b
7 ꢄ 0.27c
10 ꢄ 0.16a
7 ꢄ 0.23b
Na
Experiment was performed in triplicate and expressed as mean ꢄ SD. Values with different superscripts within each column (for any bacteria in different concentrations) are
significantly different (P < 0.05).
Na: no active.

118
S.J. Sabounchei et al. / Journal of Organometallic Chemistry 761 (2014) 111e119
Fig. 4. Comparison of antibacterial activities of the studied metal complexes 1e4 (at 1 mg/ml concentration), negative control (Cu(I), Cu(II) and DMSO), and positive control
(cephalexin). Values with different superscripts (for effect of metal complexes on the each bacterium) are significantly different (P < 0.05).
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Acknowledgments
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We are grateful to the Bu-Ali Sina University for a grant.
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Appendix A. Supplementary material
CCDC 901625 contains the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
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