Palladium and platinum complexes of the new ligands containing P-N and P-O bonds

Article abstract of DOI:10.1016/j.poly.2014.06.010

A number of applications have been found for the variety complexes of Pd(II) and Pt(II) due to their marked catalytic activities. This study is intended to examine the seven and eight-membered novel complexes which have been prepared by P-N-C-C-O-P and P-

Full text of DOI:10.1016/j.poly.2014.06.010

Polyhedron 81 (2014) 203–209
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Palladium and platinum complexes of the new ligands containing P–N
and P–O bonds
a,
⇑
a
a
b
c
_
Sevil Iri ßs li , Merve Karaman , Nilgün Arda , Bircan Dindar , Orhan Büyükgüngör
a
b
c
_
Department of Inorganic Chemistry, Faculty of Science, Ege University, 35100 Bornova, Izmir, Turkey
Institute of Solar Energy, Ege University, 35100 Bornova, Izmir, Turkey
Department of Physics, Faculty of Science and Literature, Samsun, Turkey
_
a r t i c l e i n f o
a b s t r a c t
Article history:
A number of applications have been found for the variety complexes of Pd(II) and Pt(II) due to their
marked catalytic activities. This study is intended to examine the seven and eight-membered novel com-
plexes which have been prepared by P–N–C–C–O–P and P–N–C–C–C–O–P backbone ligands. The air-sta-
ble complexes [M = Pd (1a, 3a), Pt (1b, 3b)] containing aminophosphine-phosphinite metallocyclic rings
were obtained with high yields. All the compounds were characterized by P{ H}, C{ H} and H NMR
spectroscopy, FTIR spectroscopy and elemental analysis. Furthermore, the structure of complexes (1a and
Received 24 March 2014
Accepted 3 June 2014
Available online 11 June 2014
3
1
1
13
1
1
Keywords:
Aminophosphine–phosphinite
Palladium–platinum complexes
Suzuki–Miyaura C–C cross coupling
Diphosphines
3a) were determined by X-ray crystallography. The novel complexes (1a and 3a) are very effective cata-
lysts on Suzuki–Miyaura cross-coupling reactions of various aryl chlorides and aryl bromides with phen-
ylboronic acid.
X-ray
Ó 2014 Elsevier Ltd. All rights reserved.
1
. Introduction
The multidentate ligands which contain different donor atoms
stereoselectivity in hydroformylation reactions [6]. However, the
catalytic activities of such types of metal complexes in the
Suzuki–Miyaura coupling reaction have not been determined in
the literature.
such as phosphorus and nitrogen, and their transition metal com-
plexes play an important role in organic and organometallic chem-
istry, enhancing the stability of complexes and allowing the
manipulation of electronic and steric parameters which control
reactivity at the metal center [1]. The phosphorus ligands are by
far the most commonly used, because they offer many more possi-
bilities for modification of the structure (mono-, di-multidendate,
hemilabile, hybrids, etc.), the symmetry (C2, dissymmetric, etc.),
the basicity, and the chirality of the phosphorus atom [2–11]. With
regard to chelating phosphorus ligands and their complexes, the
chain lengths or the bulky substituents on phosphorus atoms are
of primary importance [12]. Furthermore, the chiral diphosphine
ligands and their ruthenium, iridium, rhodium, and palladium
complexes have also been reported and were essential for the
development of new catalytic systems exhibiting high efficiency
and enantioselectivity [13–15].
In this study we synthesized 1-(diphenylphosphino)piperidine-
3-yl diphenylphosphinite (1), 3-[(diphenylphosphino)(methyl)ami
no]propyl diphenylphosphinite (2) and [1-(diphenylphosphino)pip
eridine-3-yl]methyl diphenylphosphinite (3) ligands, and their pal-
ladium (1a and 3a) and platinum (1b and 3b) derivatives. The
structures of the complexes were characterized by using different
spectroscopic methods. The crystal structures of 1a and 3a were
established by X-ray crystallography. In particular, we demon-
strated the efficiency of such complexes for Suzuki–Miyaura C–C
cross coupling of activated aryl halides over palladium catalysts.
2. Experimental
2.1. Materials and methods
Aminophosphine–phosphinite metal complexes have been used
in catalytic asymmetric hydrogenation [2,16,17] and hydroformyl-
ation reactions [18–20]. Nevertheless, platinum complexes with
chiral chelating phosphines have been shown to have a higher
Solvents were dried on suitable drying agents and purified
under inert conditions [21]. All synthesis was carried out using
standard Schlenk tube techniques in an inert argon atmosphere.
3-hydroxypiperidine, 3-(methylamino)propan-1-ol, 3-piperidine-
methanol, diphenylchlorophosphine, and triethylamine were pur-
chased from Aldrich and toluene, dichloromethane, diethylether,
and acetone were purchased from Merck. The starting complexes,
⇑
Corresponding author. Tel.: +90 232 3884000x2454; fax: +90 232 3888264.
_
E-mail address: irislisevil@hotmail.com (S. Iri ßs li).
2 2
[PdCl (COD)] and [PtCl (COD)] (COD = 1,5-cyclooctadiene), which
http://dx.doi.org/10.1016/j.poly.2014.06.010
277-5387/Ó 2014 Elsevier Ltd. All rights reserved.
0

_
2
04
S. Iri ßs li et al. / Polyhedron 81 (2014) 203–209
are used for the preparation of new phosphine complexes, were
synthesized according to the method given in the literature
(162 MHz, CDCl
3
) ppm: d = 117 (d, P–O), and d = 91.6 (d, P–N), IR,
(Pd–Cl). Anal. Calc. for C28 NOP Pd
À1
cm
(CsI): 279, 317
m
H
29Cl
2
2
[
22,23].
(MW = 634.76): C, 52.98; H, 4.60; N, 2.21. Found: C, 52.36; H,
5.01; N, 2.45%.
3
1
P{ H} NMR, H NMR and 13C NMR spectra were recorded on a
1
1
Varian AS 400 MHz spectrometer. CDCl was employed as a
3
solvent. J values are given in Hz. The IR spectra were obtained by
Perkin-Elmer FT-IR spectrometer. Melting points were determined
using electrothermal melting point detection apparatus. Elemental
2.2.4. Synthesis of 3-[(diphenylphosphino)(methyl)amino]propyl
diphenylphosphinite Pt(II) chloride (1b)
PtCl
(10 mL) and added dropwise to
0.270 mmol) dissolved in CH Cl (3.0 mL). After 24 h, the raw prod-
2
COD (0.100 g; 0.270 mmol) was dissolved in CH
2 2
Cl
_
analyses were performed by the TÜBITAK-Ankara Test and Analyse
a
mixture of (0.120 g;
1
Laboratories and Scientific Research and Analysis Center Labora-
tory of Inönü University. The yields of catalytic experiments were
measured by GS (Agilent Technologies 6890N-Thermo-Finnigan
on a HP-5 capillary column and with a FID detector). X-ray data
were measured in Ondokuz Mayis University, Turkey, by using
the STOE IPDS II diffractometer. The thermal behavior of newly
synthesized compounds was investigated using thermogravimetry
2
2
uct was concentrated with a vacuum and precipitated with hexane
(10 mL). The product was dried using a vacuum. Yield 0.12 g, 62%,
1
m.p = 186–189 °C, H NMR (400 MHz, CDCl
3
) ppm: d = 1.90 (m, 2H,
–CH
3.62–3.60 (m, 2H, –OCH
NMR (100 MHz, CDCl ) ppm: d = 36.2 (d, N–CH
49.4–49.7 (dd, –CH –N), 66.2–66.9 (dd, –CH–O), 124–138 (m, Ar),
P{ H} NMR (162 MHz, CDCl ppm: d = 88.7 (d, P–O) and
d = 63.6 (d, P–N), Anal. Calc. for C28 NOP Pt (MW = 723.47):
2
–), 2.20–2.17 (m, 3H, N–CH
–), 7.22–8.19 (m, 20H, Ar–H), C{ H}
), 32.1 (t, –CH –),
3
), 3.09–2.99 (m, 2H, –NCH –),
2
1
13
2
3
3
2
(
TGA/DTG) on Perkin Elmer Pyris 6.
2
3
1
1
3
)
2
2
.2. Synthesis of products
H29Cl
2
2
C, 46.84; H, 4.04; N, 1.94. Found: C, 47.01; H, 4.70; N, 1.06%.
.2.1. Synthesis of 3-[(diphenylphosphino)(methyl)amino]propyl
diphenylphosphinite ligand (1)
2.2.5. General procedure for the synthesis of 1-
Triethylamine (0.860 mL; 0.630 g; 6.20 mmol) in toluene
(diphenylphosphino)piperidine-3-yl diphenylphosphinite metal
complexes [Pd (3a) and Pt (3b)]
(
5.0 mL) was slowly added to a suspension of 3-(methylamino)pro-
pan-1-ol (0.300 mL; 0.280 g; 3.10 mmol) in toluene (10.0 mL).
Then the mixture was cooled to À78 °C. A solution of PPh Cl
1.03 mL; 1.37 g; 6.20 mmol) in toluene (5.0 mL) was slowly added
dropwise. After addition, the mixture was stirred at room temper-
ature for 24 h. Et
evaporated under vacuum and a light yellow oil was formed.
NMR (400 MHz, CDCl , 25 °C): d = 1.78–1.83 (m, 2H, –CH
.24–2.48 (m, 3H, N–CH ), 3.06–3.12 (m, 2H, N–CH
m, 2H, O–CH –), 7.06–7.70 (m, 20H, ArH).
100 MHz, CDCl ) ppm: d = 35.8 (d, N–CH ), 32.7 (t, –CH
9.8 (dd, –CH –N), 66.8–67.9 (dd, –CH–O), 126–140 (m, Ar–C),
P{ H} NMR (162 MHz, CDCl ): d = 113 ppm (P–O) and
d = 65.3 ppm (P–N).
To a suspension of 3-hydroxypiperidine (0.05 g; 0.53 mmol) in
2
toluene (10 mL), Et
3
N (0.200 g; 0.200 mL; 1.00 mmol) was added.
Cl
(
Then, the mixture was cooled to À78 °C. A solution of PPh
2
(0.220 g; 1.00 mmol; 0.190 mL) in toluene (10 mL) was slowly
added dropwise and stirred at À78 °C for 1 h and the temperature
was raised to 0 °C. Stirring was maintained at 0 °C for 1 h and then
at room temperature for 30 min. For reasons concerning oxidation,
3
NÁHCl was separated with canula. Toluene was
1
H
3
2
–),
2
(
(
3
2
–), 3.77–3.72
the solution was not filtered. So, MCl
2 2
(COD) (0.530 mmol of PdCl
1
3
1
2
C{ H} NMR
–), 49.3–
(COD) or PtCl (COD)) was added to the solution of in situ prepared
2
3
3
2
ligand, 1-(diphenylphosphino)piperidine-3-yl-diphenylphosphi-
nite. The reaction mixture was heated to reflux temperature and
stirred for 4 h. The solvent was removed under vacuum. The raw
4
2
3
1
1
3
2
product was washed with acetone, water and Et O, respectively.
It was possible for it to be recrystallized from the dichlorometh-
ane/ether (v:v = 1:3) system.
2
.2.2. Synthesis of [1-(diphenylphosphino)piperidine-3-yl]methyl
diphenylphosphinite ligand (2)
-piperidinemethanol (0.100 mL;0.860 mmol) was dissolved
in Et (5.0 mL) in standard Schlenk tube. Then, PPh Cl
0.240 mL;1.71 mmol) in Et N (10 mL) was added to this solution.
The mixture was heated to reflux temperature for 24 h. Et
For complex 3a: Yield: 0.25 g, 88%; m.p = 218–220 °C, 1H NMR
3
(400 MHz, CDCl
3
): d = 1.64 (dd, 2H, –CH
–, piperidine), 3.25 (q, 2H, N–CH
–N, piperidine), 4.58 (t, 1H, CH-O, piperidine), 7.19–8.07
2
–, piperidine), 2.99 (m,
3
N
a
2
2H, –CH
2H, –CH
2
2
–, piperidine), 3.60 (m,
(
3
2
1
3
1
3
NÁHCl
(m, 20H, ArH), C{ H} NMR (100 MHz, CDCl
piperidine), 28.9 (s, –CH –, piperidine), 46.5 (s, N –CH
dine), 52.1 (s, –CH –N, piperidine), 70.8 (d, –CH–O, piperidine),
3
): d = 19.3 (s, –CH
2
–,
was separated with canula. The solvent was evaporated under a
2
2
–, piperi-
vacuum and an off-white viscous film was formed. (Yield 75%)
2
31
1
1
H NMR (400 MHz, CDCl
3
, 25 °C): d = 0.84–1.23 (m, 2H, –CH
–, piperidine), 2.14–2.18
m, H, –CH–, piperidine), 2.81–2.98 (t,4H, N–CH –), 3.38–3.73
2
–,
126–134 (m, Ar), P{ H} NMR (162 MHz, CDCl
(d, P–N), 99.3 ppm (d, P–O), IR, cm (CsI): 283, 306
3
): d = 91.7 ppm
(Pd–Cl), Anal.
À1
piperidine), 1.60–1.69 (m, 2H, –CH
2
m
(
(
(
2
3
2 2
Calc. For C29H29Cl NOP Pd (MW = 646.77): C, 57.07; H, 4.62; N,
1
1
m, 2H, O–CH
162 MHz, CDCl
2
–), 7.08–7.55 (m, 20H, ArH).
P{ H} NMR
2.29. Found: C, 57.76; H, 4.68; N, 2.35%.
3
): d = 113 ppm (P–O) and d = 64.1 ppm (P–N).
For complex 3b: Yield: 0.23 g; 87%; m.p = 184–185 °C, 1H NMR
(
400 MHz, CDCl
2H, –CH –, piperidine), d = 3.16 (q, 2H, N–CH
(m, 2H, –CH –N, piperidine), 5.03 (t, 1H, CH–O, piperidine),
7.23–8.21 (m, 20H, ArH), C NMR (100 MHz, CDCl
(s, –CH –, piperidine), 29.1 (s, –CH –, piperidine), 44.9 (s, N –CH
piperidine), 51.9 (s, –CH
dine), 127–134 (m, Ar–C),
3
): d = 1.93 (dd, 2H, –CH
2
–, piperidine), 2.99 (m,
2
.2.3. Synthesis of 3-[(diphenylphosphino)(methyl)amino]propyl
diphenylphosphinite Pd(II) chloride (1a)
PdCl COD (0.080 g; 0.280 mmol) in CH
to the stirred solution in CH Cl (5.0 mL) of ligand 1 (0.130 g;
.280 mmol) dropwise at room temperature. The color turned from
yellow to orange. After stirring for 24 h, CH Cl was removed under
2
2
–, piperidine), 3.69
2
1
3
2
2
Cl
2
(10 mL) was added
3
): d = 19.1
–,
2
2
2
2
2
0
2
–N, piperidine), 70.5 (d, –CH–O, piperi-
3
1
1
2
2
P{ H} NMR (162 MHz, CDCl
3
):
À1
vacuum. The crude product was washed with hexane (3.0 mL) and
acetone (2.0 mL), and then dried using a vacuum. Yellow solid was
d = 65.5 ppm (P–N), 72.0 ppm (P–O), IR, cm
309 (Pt–Cl), Anal. Calc. For C29 NOP
(CsI): 285,
m
H29Cl
2
2
Pt (MW = 735.47): C,
1
obtained. Yield 0.18 g, 72%, m.p = 174 °C (decomposed), H NMR
47.36; H, 3.97; N, 1.90. Found: C, 46.11; H, 4.19; N, 2.13%.
(
3
400 MHz, CDCl
H, N–CH ), 3.05–2.96 (m, 2H, –NCH
OCH –), 7.19–8.18 (m, 20H, ArH), C{ H} NMR (100 MHz, CDCl
ppm: d = 36.7 (d, N–CH ), 31.4 (t, –CH –), 49.5–49.9 (dd, –CH
N), 67.2–67.5 (dd, –CH–O), 125–138 (m, Ar–C), P{ H} NMR
3
) ppm: d = 1.81 (m, 2H, –CH
2
–), 2.18–2.16 (m,
3
2
–), 3.63–3.58 (m, 2H, –
2.3. General procedure for the Suzuki–Miyaura coupling reactions
13
1
2
3
)
3
2
2
–
In a typical run, a two-necked 25 mL flask fitted with a reflux
condenser and septum was charged with aryl halide (1.00 mmol).
31
1

_
S. Iri ßs li et al. / Polyhedron 81 (2014) 203–209
205
Phenylboronic acid (1.50 mmol), Cs
diethyleneglycol di-n-butyl ether (0.6 mmol, internal standard)
2
CO
3
or K
2
CO
3
(1.50 mmol),
same reaction pathway from 3-hydoxypiperidine and diphenyl-
chlorophosphine but not isolated.
and the palladium–phosphine catalyst (0.1 mmol%) in DMF
For reasons related to oxidation, 1-(diphenylphosphino) piperi-
dine-3-yl diphenyl phosphinite ligand could not be isolated as a
pure product. All the isolation and purification studies failed. Also,
when the solvent was removed by vacuum, the ligand was
oxidized. Because of this, there were lots of complicated peaks in
(
3.0 ml) were added, in that order. The flask was placed in a pre-
heated oil bath (100 °C) under an argon atmosphere. The conver-
sion was monitored using gas chromatography.
3
1
1
the P{ H} NMR spectrum of this mixture and it could not be char-
acterized using any spectroscopic methods. So, the metal com-
plexes, 3a and 3b were synthesized without isolation of ligand 3
according to one-pot method described in the literature [25,26].
2.4. Thermal Stability (TGA) of 1a and 3a
The thermal stability of complexes (1a and 3a) was investigated
using the method of TGA-DTG.
3
1
1
1
and 2 ligands were isolated and analyzed with P{ H} NMR.
The thermal stabilities of these complexes were also fulfilled by
a Perkin Elmer Pyris 6 TGA instrument. The analysis was carried
out using around 3.0 mg of the dry samples directly weighed on
the pans. The temperature progressed from 50 to 900 °C and its
3
1
1
Both of them were overly sensitive to air. The P{ H} NMR spectra
of 1 and 2 show two single resonances at 113 ppm (P–O) 65.3 ppm
(
P–N) and 113 ppm (P–O) 64.1 ppm (P–N), respectively. Phospho-
À1
rus–phosphorus couplings were not observed.
heating rate was 20 °C min . The measurements were performed
2
The reaction of 1 with 1:1 mole ratio proportion of PdCl COD in
dichloromethane affords the chelate complex 1a in good yield. The
complex 1b was synthesized in a similar way to 1a with ligand 1
under nitrogen continuous flow (100 mL/min) in the temperature
range.
2
and PtCl COD (Scheme 2).
2.5. X-ray crystal structures of complex 1a and 3a
Complexes 3a and 3b were obtained in the reaction medium
(
Scheme 3). In contrast to these free ligands, which are quite sen-
Light yellow, single crystals of compound 1a and 3a were
obtained by a slow diffussion of a 1:3 dichloromethane/diethyl-
ether system at room temperature. The crystal dimensions of 1a
sitive to air, complexes (1a, 1b, 3a and 3b) are stable against air
and water, and can be stored in air over long periods of time. The
resulting complexes 1a, 1b, 3a and 3b were fully characterized
using multinuclear NMR techniques ( P{ H} NMR, H NMR,
NMR), FT-IR and elemental analysis.
0
.34 Â 0.26 Â 0.10 mm and 3a 0.47 Â 0.25 Â 0.04 mm were used
for data collection. Intensity data for complexes 1a and 3a were
collected on STOE IPDS II diffractometer using graphite-
monochromated Mo K radiation (k = 0.71073 Å) at 296 K. A total
of 8224 and 4821 reflections that had I > 2 (I) were regarded as
31
1
1
13
C
a
2
For the complex 1a, the –NPPh resonance is 25.7 ppm down-
a
field (d 91.6 ppm) from that of the free ligand, similarly the –OPPh
2
r
31
1
signal shifted only 4 ppm downfield (d 117 ppm). P{ H} NMR
spectrum of complex 3a, revealed significant shifts of the doublets
at 91.7 ppm, P(N) and 99.3 ppm, P(O) assigned to the diphenyl-
phosphino groups coordinated to nitrogen and oxygen [17]. Thus,
it is confirmed that the two phosphorus atoms are not magneti-
cally equivalent and that the structure is not symmetric in the
complexes 1a and 3a.
observed and used for complexes 1a and 3a, in the structure anal-
ysis. All positional and thermal parameters were refined using the
SHELXL-97 program [24]. The hydrogen atoms were identified in the
difference Fourier map and were included in the refinement pro-
cess as fixed contributions. Atomic coordinates, bond lengths and
angles were deposited with the Cambridge Crystallographic Data
Center, 12 Union Road, Cambridge CB2 1EZ, UK.
31
1
For the platinum complex 1b, the P{ H} NMR spectrum shows
two signals as doublets for 63.6 and 88.7 ppm for the –NPPh and –
resonances whose Pt satellites are 4037 Hz ( JPt–P(N)) and
2
1
95
1
3
. Results and discussion
OPPh
205 Hz ( JPt–P(O)) and for 3b, 65.5 ppm and 72.0 ppm for the –
2
1
4
1
95
3
.1. Synthesis
NPPh
2
and –OPPh
2
resonances whose
Pt satellites are 4204 Hz
1
1
(
JPt, P(N)) and 4050 Hz ( JPt, P(O)), respectively. These values of
The new type of aminophosphine-phosphinite ligands (1 and 2)
the signals are harmonious with seven-membered aminophos-
phine-phosphinite ligands with platinum complexes in the litera-
ture [27,28].
were synthesized from the commercially available 3-piperidine-
methanol and 3-(methylamino) propan-1-ol. These compounds
and diphenylchlorophosphine reacted with triethylamine as a base
for tearing hydrogen (Scheme 1). Ligand 3 was synthesized as the
IR spectra (CsI, pellet) show two distinct M–Cl stretching vibra-
À1
tions. These values are
m
(Pd–Cl) at 279 and 317 cm (1a),
m(Pd–Cl)
C H CH
6
5
3
O
N
2
PPh Cl
2Et N
3
N
H
2
HO
o
-78 C 1h,
r.t 24h
PPh2
PPh2
Ligand 1
OH
Et N
3
O
2
PPh Cl
2
N
H
reflux, 24h
PPh
2
N
PPh2
Ligand 2
Scheme 1. Synthesis of the ligands.

_
2
06
S. Iri ßs li et al. / Polyhedron 81 (2014) 203–209
O
N
CH Cl
2 2
O
N
MCl COD
2
r.t, 24h
PPh2
PPh2
Ph2P
PPh2
M
Cl
Cl
1
M=Pd:1a; M=Pt:1b
Scheme 2. Synthesis of the complexes 1a and 1b.
Table 1
O
Crystal data, data collection and structure-refinement parameters for complex 1a and
a.
OH
3
PPh Cl, MCl COD
2
2
PPh2
1a
3a
Et N, C H CH ,
reflux, 4h
3
6
5
3
N
H
N
Empirical formula
Formula weight
Crystal color
Crystal size (mm)
T (K)
C
28
H
29Cl
2
NOP
2
Pd
C
29
H
29Cl
646.77
light yellow
2 2
NOP Pd
M
Cl
Cl
634.76
light yellow
P
Ph
0.34 Â 0.26 Â 0.10 0.47 Â 0.25 Â 0.04
2
296
296
k (Å)
0.71073
monoclinic
P21/c
0.71073
monoclinic
P21/c
Crystal system
Space group
Description
Unit cell dimension
a (Å)
M=Pd:3a; M=Pt:3b
prism
prism
Scheme 3. Synthesis of the complexes 3a and 3b.
8.9898(3)
14.4971(6)
21.9507(7)
90.00
106.303(2)
90.00
20.5304(12)
14.4110(5)
22.1063(15)
90.00
120.557(4)
90.00°
b (Å)
c (Å)
À1
À1
at 283 and 306 cm
m
(3a),
m
(Pt–Cl) at 318 and 337 cm
(1b),
À1
a
(°)
b (°)
(°)
(Pt–Cl) at 285 and 309 cm
(3b) consistent with a cis-MCl
2
geometry. Additionally, this structure was also supported with
c
events of elemental analysis.
Z
4
8
À1
Absorption coefficient (mm
D
V (Å )
Theta range (°)
Index ranges
)
1.009
1.536
0.986
1.526
It was attempted to synthesize the pincer complexes of
palladium and platinum by use of ligand 1 and ligand 3. For this
purpose, we changed lots of parameters such as different
solvents (toluene, THF, dichloromethane, pentanol, chloroform–
3
calc (Mg/m )
3
2745.72(17)
1.71–28.07
À11 < h < 11,
À18 < k < 18,
À27 < l < 27
1288
5632.1(5)
1.41–27.33
À25 < h < 25,
À17 < k < 18,
À27 < l < 27
2624
3
trichloroaceticacid), several bases (BuLi, Et N, dimethylaminopyri-
dine) and varied temperatures. But there was no result from these
experiments. Also, when synthesizing of the platinum and
palladium complexes of the ligand 2, the reaction conditions (sol-
vent, temperature) were changed but we were unable to achieve
pure products.
F(000)
Measured reflections
Independent reflections (Rint
Absorption correction
29374
76053
11668 (0.0688)
)
5698 (0.0399)
integration Stoe
X-RED32 [29]
0.0679
0.0648
1.02
Final R indices (all data) R
, [I > 2 (I)]
Goodness-of-fit (GOF) on F
Maximum/minimum trans. (e Å
1
,
0.0866
0.0514
1.07
R
1
r
2
3.2. X-ray crystal structures of complexes 3-
À3
)
0.91/0.72
0.87/0.70
[(diphenylphosphino)(methyl)amino]propyl diphenylphosphinite
Pd(II) chloride (1a) and 1-(diphenylphosphino)piperidine-3-yl
diphenylphosphinite Pd(II)chloride (3a)
Cl(1)–Pd(1)–P(1) and 98.99(4)° for P(1)–Pd(1)–P(2); 84.78(4)° for
P(2)–Pd(1)–Cl(2); 92.84(4)° for Cl(2)–Pd(1)–Cl(1); 84.72(4)°
for Cl(1)–Pd(1)–P(1), respectively. Due to these steric effects, the
P–Pd–P and Cl–Pd–Cl angles around the Pd center are opened up
and are significantly larger than 90°.
The light yellow crystals of 1a and 3a were grown by a slow dif-
fusion technic from a dichloromethane-diethylether (v:v = 1:3)
solvent system in diffusion at room temperature. The details of
the structure determinations are given in Table 1 and selected
bond lengths and angles are listed in Table 2. Views of the mole-
cules 1a and 3a are depicted in Fig. 1 and Fig. 2, respectively,
together with the numbering scheme adopted. They have seven-
membered and eight-membered macrocyclic units, respectively.
Palladacycles 1a and 3a both crystallized in the monoclinic P21/
c, space group. The X-ray crystal data demonstrate that each palla-
dium metal is located in a distorted square-planar geometry sur-
rounded by a chelating aminophosphine–phosphinite ligand and
chloride anions. The assymetric unit of the structure of compound
The metal–phosphorus bond lengths, Pd–P(O) and Pd–P(N), are
slightly different from each other in complex 1a and 3a. As
expected, the Pd–Cl bond lengths trans to –OPPh
2
groups are
slightly shorter than the Pd–Cl bond lengths trans to –NPPh
2
groups due to the trans effect. The six-membered piperidine rings
in the two molecules of complex 3a are chair conformations.
3.3. Catalysis
3
a contains two crystallographically independent molecules.
Analysis of 1a and 3a reveals the palladium centers to be
The palladium-catalyzed cross-coupling of arylboronic acids
with aryl halides (bromoacetophenone, chloroacetophenone,
bromoanisole, chloroanisole) has been shown to proceed under a
variety of conditions; a wide range of bases and solvents, as well
located into
a slightly distorted square planar environment
with angles of 97.24(2)° for P(1)–Pd(1)–P(2); 85.43(2)° for P(2)–
Pd(1)–Cl(2); 90.61(3)° for Cl(2)–Pd(1)–Cl(1); 86.78(2)° for

_
S. Iri ßs li et al. / Polyhedron 81 (2014) 203–209
207
Table 2
Until now, various metal complexes of aminophosphine–
phosphinites have been investigated for the asymmetric allylic
alkylation, hydroformylation, and hydrogenation [6,20,31,32].
However, there is no literature concerning the catalytic activity
of aminophosphine-phosphinite type palladium complexes in
cross coupling reactions. So we have investigated the activity of
complexes 1a and 3a as catalysts for the coupling of various aryl
bromides and chlorides with phenyl boronic acid. The results of
this study are summarized in Table 3. The conditions employed
for the catalytic experiments are depicted on Scheme 4. Better per-
formances can be obtained by changing the reaction conditions.
Observations on these catalysis reactions are consistent with a
classical Pd(0)/Pd(II) catalytic cycle. Reaction mixtures begin turn-
ing yellow fairly soon after being heated in an oil bath. At 100 °C,
color changes became evident within about 1 min. Reaction mix-
tures involving aryl chlorides slowly turned yellow at 100 °C, but
no black precipitate was evident [33].
Selected bond distances (Å) and angles (°) for complex 1a and 3a.
1
a
3a
Bond distances
P1–Pd1
P2–Pd1
Cl1–Pd1
Cl2–Pd1
N1–P2
2.2368(6)
2.2652(6)
2.3694(6)
2.3516(7)
1.6704(19)
1.5947(15)
1.446(3)
P1–Pd1
P2–Pd1
Cl1–Pd1
Cl2–Pd1
N1–P2
2.2427(11)
2.2489(12)
2.3750(12)
2.3499(11)
1.666(4)
O1–P1
O1–C1
O1–P1
O1–C28
1.611(3)
1.460(5)
Bond angles
O1–P1–Pd1
N1–P2–Pd1
P1–Pd1–P2
P2–Pd1–Cl2
P1–Pd1–Cl1
Cl2–Pd1–Cl1
118.58(6)
123.99(8)
97.24(2)
85.43(2)
86.78(2)
90.61(3)
O1–P1–Pd1
N1–P2–Pd1
P1–Pd1–P2
P2–Pd1–Cl2
P1–Pd1–Cl1
Cl2–Pd1–Cl1
119.52(12)
117.16(14)
98.99(4)
84.78(4)
84.72(4)
92.84(4)
The complexes 1a and 3a were active catalysts for the Suzuki–
Miyaura cross coupling reaction with tolerable yields and TON val-
ues. For catalysts of 1a and 3a, the coupling of 4-bromoacetophe-
none with phenylboronic acid proceeds with a 99% isolated
yield with a catalyst loading of 0.1 mmol%, while electronically
as catalysis [30]. The reactions are usually carried out homoge-
neously in the presence of a base in an inert atmosphere. The reac-
tivity of the aryl halide component decreases drastically in the
order X = Br > Cl. This optimized set of coupling reaction conditions
is used for catalytic experiments.
Fig. 1. Molecular structure of complex 1a with 30% probability level ellipsoids. Hydrogen atoms are omitted for clarity.
Fig. 2. Molecular structure of complex 3a with 30% probability level ellipsoids. Hydrogen atoms and the second molecule are omitted for clarity.

_
2
08
S. Iri ßs li et al. / Polyhedron 81 (2014) 203–209
Table 3
The Suzuki coupling reaction of aryl halides with phenylboronic acid of catalysts 1a and 3a (in DMF).
Entry
Catalyst
Substrat
Base
Time
% Yield
TON
1
2
3
4
5
6
7
8
1a
1a
1a
1a
3a
3a
3a
3a
4-bromoacetophenone
4-chloroacetophenone
4-bromoanisole
Cs
Cs
Cs
Cs
2
2
2
2
CO
CO
CO
CO
3
3
3
3
0.13
10
6
24
1
24
2
24
>99
>99
97
2.5
>99
53
>990000
>990000
970000
25000
>990000
530000
890000
410000
4-chloroanisole
4-bromoacetophenone
4-chloroacetophenone
4-bromoanisole
K
2
K
2
K
2
K
2
CO
CO
CO
CO
3
3
3
3
89
41
4-chloroanisole
loss) for the 1a and 3a complexes, respectively. The remaining
5% should correspond to the mass of PdCl
B(OH)2
X
R
2
2
.
%
0.1mmol catalyst
R
Cs CO /K CO
2
4. Conclusion
3
2
3
o
DMF 100 C
Aminophosphine-phosphinite type ligands (1 and 2) and their
chelated Palladium (1a and 3a) and Platinum (1b and 3b) com-
plexes were synthesized. The crystal structures of 1a and 3a were
determined through X-ray crystallographic studies. 1a and 3a com-
plexes were found to be active catalysts on Suzuki–Miyaura C-C
cross coupling reactions between 4-bromoacetophenone, 4-chloro-
acetophenone, 4-bromoanisole and phenylboronic acid.
R=COCH
X=Cl,Br
3 3
, OCH
Scheme 4. The mechanism of Suzuki–Miyaura coupling reaction.
deactivated. Thus, the more challenging substrate 4-bromoanisole
can be efficiently coupled with 89% and 97% isolated yield with a
catalyst loading of 0.1 mmol%, while the catalysts, 1a and 3a, are
said to be more active compared with the amido phosphine palla-
dium complex [34].
The catalytic activities of 1a and 3a, were seen to decrease from
p-bromoacetophenone to p-bromoanisole. This is ascribed to the
presence of the electron donating metoxy group which makes
the substrate less reactive in the rate determining step of the cat-
alytic cycle [35]. The complex 1a efficiently catalyzes the Suzuki
cross-couplings of a range of aryl boronic acid and 4-chloroaceto-
phenone, affording high isolated yields at a low catalyst load
Acknowledgements
_
We are grateful to the TÜBITAK with science Project 110T786.
Ege University/TURKEY (2009 FEN 091 and 2012 FEN 048) for
_
financial support. We also wish to thank the EBILTEM/TURKEY
for equipment grants. The authors acknowledge the Faculty of Arts
and Sciences, Ondokuz Mayis University, Turkey, for the use of the
STOE IPDS II diffractometer (purchased under Grant F.279 of the
University Research Fund/TURKEY).
(
0.1 mmol% 1a) to give 1-biphenyl-4-ylethanone in a good TON
Appendix A. Supplementary data
of >99 0000 [36].
The activity of 1a is comparable to that of some Palladium com-
plexes, which catalyzed the Suzuki coupling of 4-chloroacetophe-
none with phenylboronic acid, giving up to 99% yield at
CCDC 920704 and 977709 contain the supplementary crystallo-
graphic data for compounds 1a and 3a, respectively. These data can
be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/
retrieving.html, or from the Cambridge Crystallographic Data
Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223
336 033; or e-mail: deposit@ccdc.cam.ac.uk.
0
.1 mmol% of 1a under ambient conditions [33,37].
Van Leeuwen and co-workers performed a study on the effect of
the bite angle of chelating diphosphines on the activity and selec-
tivity in the palladium-catalyzed cross-coupling reactions. Increas-
ing the P–M–P angle of the diphosphine to even larger values
resulted in a decrease of catalyst activity and also selectivity. So,
the high catalytic activities for 1a and 3a can be explained by the
small P–Pd–P bite angles [38–40].
Finally, complexes 1a and 3a are ideal to catalyze the coupling
of electronically deactivated substrate and aryl bromides or chlo-
rides as they are comparatively inexpensive and can be used to
give high conversion at low concentrations of catalysts.
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