Aminophosphine-palladium(II) complexes: Synthsesis, structure and applications in Suzuki and Heck cross-coupling reactions

Article abstract of DOI:10.1016/j.ica.2011.07.056

Reaction of furfurylamine with 1 or 2 equivalents of PPh₂Cl in the presence of Et₃N, proceeds under anaerobic conditions in thf to give furfuryl-2-(N-diphenylphosphino)amine, Ph₂PNHCH ₂-C₄H₃

Full text of DOI:10.1016/j.ica.2011.07.056

Inorganica Chimica Acta 378 (2011) 10–18
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Inorganica Chimica Acta
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Aminophosphine–palladium(II) complexes: Synthsesis, structure and applications
in Suzuki and Heck cross-coupling reactions
a
b
a
c
Murat Aydemir a, , Akin Baysal , Ertan Sahin , Bahattin Gumgum , Saim Ozkar
⇑
a Dicle University, Department of Chemistry, TR-21280 Diyarbakır, Turkey
b Atatürk University, Department of Chemistry, TR-25240 Erzurum, Turkey
c Middle East Technical University, Department of Chemistry, TR-06531 Ankara, Turkey
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 1 April 2011
Received in revised form 27 July 2011
Accepted 30 July 2011
Available online 11 August 2011
Reaction of furfurylamine with 1 or 2 equivalents of PPh2Cl in the presence of Et3N, proceeds under
anaerobic conditions in thf to give furfuryl-2-(N-diphenylphosphino)amine, Ph2PNHCH2-C4H3O,
1
and furfuryl-2-(N,N-bis(diphenylphosphino)amine), (Ph2P)2NCH2-C4H3O, 2, respectively. The reactions
of 1 and 2 with MCl2(cod) (M = Pd, Pt; cod = 1,5-cyclooctadiene) or Pt(CH3)2(cod) yield complexes
[M(Ph2PNHCH2-C4H3O)2Cl2] (M = Pd 1a, Pt 1b), [Pt(Ph2PNHCH2-C4H3O)2(CH3)2] (1c), and [M((Ph2P)2
NCH2-C4H3O)Cl2] (M = Pd 2a, Pt 2b), [Pt((Ph2P)2NCH2-C4H3O)(CH3)2] (2c), respectively. All the com-
pounds were isolated as analytically pure substances and characterized by NMR, IR spectroscopy
and elemental analysis. Representative solid-state structures of 2a and 2b were also determined by
X-ray single crystal diffraction technique. Furthermore, the palladium complexes 1a and 2a were
tested and found to be highly active catalysts in the Suzuki coupling and Heck reaction affording
biphenyls and trans-stilbenes, respectively.
Keywords:
Aminophosphine
Furfurylamine
Palladium
Platinum
Heck reaction
Suzuki coupling
Ó 2011 Elsevier B.V. All rights reserved.
1. Introduction
and Suzuki reactions is noteworthy in this area, where significant
advances have culminated to provide an important step-change
Phosphorus–nitrogen containing ligands have particular use in
catalysis where it is necessary for part of ligand to dissociate to al-
low an organic fragment to coordinate and undergo transforma-
tions [1]. Small variations in these ligands can cause significant
changes in their coordination behavior and the structural features
of the resulting complexes. Synthesis of new aminophosphines to
stabilize transition metals in low valent states is considered to be
a most challenging task in view of their potential utility in a variety
of metal-mediated organic transformations [2–4]. To date, a num-
ber of such systems with a variety of backbone frameworks have
been synthesized and their transition metal chemistry has been ex-
plored [5–7]. Tertiary phosphines have long been used in the syn-
thesis of transition metal complexes with catalytic properties,
especially with electron-rich transition metals like nickel, palla-
dium, platinum and rhodium [8–10].
[12–15]. In addition to the high catalytic activity in these reactions,
selectivity of the catalyst, particularly chemo-, regio-, stereo- and
enantio-selectivity, is of the utmost importance [16]. Because of
their remarkable catalytic potential and their large versatility, pal-
ladium complexes have become the most popular organometallics
used in organic synthesis [17]. In particular, palladium catalysts
have been used in most of the carbon–carbon bond formation reac-
tions such as Heck and Suzuki reactions [18] which are powerful
tools for the preparation of unsymmetrical biaryl [19,20] and stil-
bene compounds [21].
Recently, various bulky and electron-rich phosphines have been
developed as ligands to promote the cross-coupling reactions [22].
We have shown that aminophosphine and bis(aminophosphine)
palladium(II) complexes offer distinct advantages for Pd/phos-
phine system in the Suzuki and Heck cross-coupling reactions
[23,24]. Extending our study to develop useful catalysts, herein,
we report the coordination chemistry of two furfurylamine-func-
tionalised aminophosphine ligands with palladium(II) and plati-
num(II) ions. The structures of all new compounds have been
elucidated by a combination of multinuclear NMR spectroscopy,
IR spectroscopy, elemental analysis and by X-ray crystallography.
In addition, we tested the catalytic activities of palladium com-
plexes in the Suzuki and Heck coupling reactions.
Transition metal catalysts have been used in a variety of syn-
thetic transformations, including the formation of carbon–carbon
and carbon-heteroatom bonds through cross-coupling [11]. The
development of highly active catalysts for Heck, Sonogashira, Stille,
⇑
Corresponding author. Tel.: +90 412 248 8550; fax: +90 412 248 8300.
E-mail address: aydemir@dicle.edu.tr (M. Aydemir).
0020-1693/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2011.07.056

M. Aydemir et al. / Inorganica Chimica Acta 378 (2011) 10–18
11
2.5. Synthesis and characterization of ligands and their complexes
2.5.1. Synthesis and characterization of ligands
2. Experimental
2.1. General
2.5.1.1. Furfuryl-(N-diphenylphosphino)amine, [Ph2PNHCH2-C4H3O],
(1). Chlorodiphenylphosphine (0.237 g, 1.02 mmol) was added
dropwise over a period of 15 min to a stirred solution of furfuryl-
amine (0.099 g, 1.02 mmol) and triethylamine (0.104 g,
1.02 mmol) in thf (40 mL) at 0 °C. The mixture was then stirred
at room temperature for 1 h and the white precipitate (triethylam-
monium chloride) was filtered under argon and the solvent was re-
moved under reduced pressure. The residue was then washed with
cold diethyl ether (2 ꢁ 10 mL) and dried in vacuo to produce a
clear, white viscous oily compound 1 (yield: 0.261 g, 91.1%); 1H
NMR (CDCl3, 400.1 MHz, Me4Si): d 7.45–7.48 (m, o-protons of
phenyls, 4H), 7.36–7.41 (m, m- and p-protons of phenyls, 6H),
7.35 (d, H-5, 1H, 3J 2.0 Hz), 6.30 (dd, H-4, 1H, 3J 2.0 and 3.2), 6.11
(d, H-3, 1H, 3J 3.2 Hz), 4.01 (dd, –CH2–, 2H, 3J 6.8 and 8.8 Hz),
Unless otherwise stated, all reactions were carried out under an
atmosphere of argon using conventional Schlenk glass-ware and
solvents were dried using established procedures and distilled un-
der argon just prior to use. Analytical grade and deuterated sol-
vents were purchased from Merck. PPh2Cl and furfurylamine
were purchased from Fluka and used as received. The starting
materials [MCl2(cod)] (M = Pd, Pt, cod = 1,5-cyclooctadiene)
[25,26] and [Pt(CH3)2(cod)] [27] were prepared according to the lit-
erature procedures. Infrared spectra were recorded from KBr pellet
in the range 4000–400 cmꢀ1 on a Mattson 1000 ATI UNICAM FT-IR
spectrometer. 1H (400.1 MHz), 13C NMR (100.6 MHz) and 31P–{1H}
NMR (162.0 MHz) spectra were recorded on a Bruker AV 400 spec-
trometer, with d referenced to external TMS and 85% H3PO4,
respectively. Elemental analysis was carried out on a Fisons EA
1108 CHNS-O instrument. Melting points were determined by
Gallenkamp Model apparatus with open capillaries.
2.38 (dt, –NH–, 1H,
J
6.8 and 13.2 Hz); 13C NMR (CDCl3,
100.6 MHz, Me4Si): d 154.95 (d, C-2, 3J(31P–13C) 6.0 Hz), 141.71
(d, C-5), 140.95 ppm (d, i-carbons of phenyls, 1J(31P–13C)
12.1 Hz), 131.44 (d, o-carbons of phenyls, 2J(31P–13C) 19.0 Hz),
128.58 (s, p-carbons of phenyls), 128.30 (d, m-carbons of phenyls,
3J(31P–13C) 6.3 Hz), 110.26 (C-4), 106.27 (C-3), 43.09 (–CH2–);
assignment was based on the 1H–13C HETCOR and 1H–1H COSY
spectra; 31P–{1H} NMR (CDCl3, 162.0 MHz, 85% H3PO4): d 42.71
2.2. GC analysis
GC analyses were performed on a HP 6890N instrument
equipped with a capillary column (5% biphenyl, 95% dimethylsilox-
(s); selected IR (KBr pellet, in cmꢀ1):
(N–H) 3383; Anal. Calc. for C17H16ONP (mw: 281.3 g/mol): C,
m(P–N) 804, m(P–Ph) 1434,
m
ane; 30 m ꢁ 0.32 mm i.d. ꢁ 0.25
lm film thickness). The GC
72.59; H, 5.73; N, 4.98. Found: C, 72.49; H, 5.64; N, 4.95%.
parameters for Suzuki coupling reactions were as follows: initial
temperature, 50 °C; initial time, 1 min; solvent delay, 3.70 min;
temperature ramp 1, 10 °C/min; final temperature, 150 °C; temper-
ature ramp 2, 15 °C/min; final temperature, 250 °C; final time,
20.67 min; injector port temperature, 250 °C; detector tempera-
2.5.1.2. Furfuryl-(N,N-bis(diphenylphosphino))amine, [(Ph2P)2NCH2-
C4H3O], (2). Chlorodiphenylphosphine (0.4734 g, 2.04 mmol) was
added to a solution of furfurylamine (0.099 g, 1.02 mmol) and tri-
ethylamine (0.200 g, 2.04 mmol) in thf (50 mL) at 0 °C with vigor-
ous stirring. The mixture was then stirred at room temperature for
2 h and the white precipitate (triethylammonium chloride) was fil-
tered under argon and the solvent was removed under reduced
pressure. The residue was then washed with cold diethyl ether
(2 ꢁ 15 mL) and dried in vacuo to produce a yellow viscous oily
compound 2 [28] (yield: 0.215 g, 88.8%). 1H NMR (d in ppm rel.
to TMS, J Hz, in CDCl3): d 7.37–7.44 (o-protons of phenyls, 8H),
7.28–7.33 (m, m and p-protons of phenyls, 12H), 7.13 (br, H-5,
1H), 6.11 (br, H-4, 1H), 5.48 (br, H-3, 1H), 4.34 (t, –CH2–, 2H, 3J
8.6 Hz); 13C NMR (d in ppm rel. to TMS, J Hz, in CDCl3): d 153.50
(C-2), 141.34 (C-5), 139.02 ppm (d, i-carbons of phenyls,
1J(31P–13C) 5.94 Hz), 132.76 (t, o-carbons of phenyls, 2J(31P–13C)
11.1 Hz), 128.75 (s, p-carbons of phenyls), 128.10 (d, m-carbons
of phenyls, 3J(31P–13C) 3.0 Hz), 110.28 (C-4), 108.24 (C-3), 47.83
(–CH2–); assignment was based on the 1H–13C HETCOR and
1H–1H COSY spectra; 31P NMR (d in ppm rel. to H3PO4, in CDCl3):
ture, 250 °C, injection volume, 2.0 lL; for Heck coupling reactions,
initial temperature, 50 °C; initial time, 1 min; solvent delay,
3.53 min; temperature ramp, 13 °C/min; final temperature,
300 °C; final time, 40.46 min; injector port temperature, 250 °C;
detector temperature, 250 °C, injection volume, 2.0 lL.
2.3. General procedure for the Suzuki coupling reaction
Aminophosphine- or bis(phosphino)amine-palladium(II) com-
plexes (1a–2a, 0.01 mmol), aryl bromide (1.0 mmol), phenylbo-
ronic acid (1.5 mmol), Cs2CO3 (2 mmol) and dioxane (3 mL) were
added to a Schlenk tube under argon atmosphere and the mixture
was heated at 60 °C. After completion of the reaction, the mixture
was cooled, extracted with ethyl acetate/hexane (1:5), filtered
through a pad of silica gel with copious washing, concentrated
and purified by flash chromatography on silica gel. The purity of
the compounds was checked immediately by GC and NMR and
yields are based on aryl bromide.
d 62.54 (s); selected IR (KBr pellet, in cmꢀ1):
Ph) 1434; Anal. Calc. for 29H25ONP2 (mw: 465.5 g/mol): C,
m(P–N–P) 921, m(P–
C
74.83; H, 5.41; N, 3.01. Found: C, 74.72; H, 5.38; N, 3.00%.
2.4. General procedure for the Heck coupling reaction
2.5.2. Synthesis of metal [Pd(II), Pt(II)] complexes
2.5.2.1. Synthesis of
cis-dichlorobis(furfuryl-(N-diphenylphos-
Aminophosphine- or bis(phosphino)amine-palladium(II) com-
plexes (1a–2a, 0.01 mmol), aryl bromide (1.0 mmol), styrene
(1.5 mmol), K2CO3 (2 mmol), DMF (3 mL) for 1a and dioxane
(3 mL) for 2a were added to a Schlenk tube under argon atmo-
sphere and the mixture was heated to 100 °C. After completion
of the reaction, the mixture was cooled, extracted with ethyl
acetate/hexane (1:5), filtered through a pad of silica gel with
copious washing, concentrated and purified by flash chromatog-
raphy on silica gel. The purity of the compounds was checked
immediately by GC and NMR and yields are based on aryl
bromide.
phino)methylamine)palladium(II) (1a). A solution of [PdCl2(cod)]
(0.145 g, 0.51 mmol) and furfuryl-(N-diphenylphosphino)amine,
1, (0.287 g, 1.02 mmol) in thf (25 mL) was stirred for 1.5 h at room
temperature. The volume was concentrated in vacuum to ca. 1–
2 mL and addition of diethyl ether (15 mL) gave 1a as yellow solid
which was collected by filtration and dried in vacuum (yield:
0.324 g, 85.9%, mp 195–197 °C). 1H NMR (CDCl3, 400.1 MHz,
Me4Si): d 7.38–7.83 (8H, br, o-protons of phenyls), 7.38–7.83
(12H, m, m- and p-protons of phenyls), 7.23 (s, H-5, 2H), 6.21 (br,
H-4, 2H), 6.11 (br, H-3, 2H), 4.36 (s, –NH–, 2H), 3.12 (br, –CH2–,
4H); 13C NMR (CDCl3, 100.6 MHz, Me4Si): d 152.82 (C-2), 142.56

12
M. Aydemir et al. / Inorganica Chimica Acta 378 (2011) 10–18
(C-5), 133.61 (o-carbons of phenyls), 130.89 (p-carbons of phen-
yls), 129.24 ppm (i-carbons of phenyls), 128.23 (m-carbons of
phenyls), 112.45 (C-4), 105.34 (C-3), 43.09 (–CH2–); assignment
was based on the 1H–13C HETCOR and 1H–1H COSY spectra; 31P–
{1H} NMR (CDCl3, 162.0 MHz, 85% H3PO4): d 46.05 (s, NH–P–
1H NMR (DMSO, 400.1 MHz, Me4Si): d 7.84 (dd, o-hydrogen of
phenyls, 8H, 3J 7.50 and 13.50 Hz), 7.64 (t, p-hydrogen of phenyls,
4H, 3J 3.67), 7.53 (t, m-hydrogen of phenyls, 8H, 3J 7.26), 7.01 (br,
H-5, 1H), 6.11 (br, H-4, 1H), 5.79 (d, H-3, 1H, 3J 2.89 Hz), 3.95 (t,
–CH2–, 2H, 3J 11.90 Hz); 13C NMR (d in ppm rel. to TMS, J Hz, in
CDCl3): d 147.49 (C-2), 143.14 (C-5), 133.47 (t, o-carbons of phen-
yls, 2J(31P–13C) 7.65 Hz), 133.07 (s, p-carbons of phenyls), 129.22
(d, m-carbons of phenyls, 3J(31P–13C) 6.25 Hz), 134.45 ppm (d, i-
carbons of phenyls, 1J(31P–13C) 66.80 Hz), 110.80 (C-4), 110.78
(C-3), 44.82 (–CH2–); assignment was based on the 1H–13C HET-
COR and 1H–1H COSY spectra; 31P–{1H} NMR (DMSO, 162.0 MHz,
(C6H5)2); selected IR (KBr pellet, in cmꢀ1):
1437,
m(P–N) 813,
m(P–Ph)
m(N–H) 3335; Anal. Calc. for C34H32N2O2P2PdCl2 (mw:
730.91 g/mol): C, 55.19; H, 4.36; N, 3.79. Found: C, 55.02; H,
4.29; N, 3.71%.
2.5.2.2. Synthesis of cis-dichloro(furfuryl-2-(N,N -bis(diphenylphos-
phino))amine)palladium(II) (2a). A solution of [PdCl2(cod)]
1
85% H3PO4): d 19.32, (s, N–(P–(C6H5)2)2, J(PtP): 3300.84 Hz); se-
(0.291 g,
1.02 mmol)
and
furfuryl-(N,N-bis(diphenylphos-
lected IR (KBr pellet, in cmꢀ1):
m(P–N–P) 809, m(P–Ph) 1436; Anal.
phino))amine, 2, (0.475 g, 1.02 mmol) in thf (25 mL) was stirred
for 2 h at room temperature. The volume was concentrated in vac-
uum to ca. 1–2 mL and addition of diethyl ether (15 mL) gave 2a as
bright yellow solid which was collected by filtration and dried in
vacuum (yield: 0.621 g, 94.8%, mp 229–231 °C). 1H NMR (DMSO,
400.1 MHz, Me4Si): d 7.87 (dd, o-hydrogen of phenyls, 8H, 3J 6.78
and 12.42 Hz), 7.66 (t, p-hydrogen of phenyls, 4H, 3J 6.76), 7.55
(t, m-hydrogen of phenyls, 8H, 3J 6.46), 7.02 (br, H-5, 1H), 6.12
(br, H-4, 1H), 5.81 (d, H-3, 1H, 3J 3.52 Hz), 4.06 (t, –CH2–, 2H, 3J
11.80 Hz); 13C NMR (d in ppm rel. to TMS, J Hz, in CDCl3): d
147.06 (C-2), 143.17 (C-5), 133.62 (t, o-carbons of phenyls,
2J(31P–13C) 6.54 Hz), 133.27 (s, p-carbons of phenyls), 129.44 (d,
m-carbons of phenyls, 3J(31P–13C) 6.04 Hz), 126.53 ppm (d, i-car-
bons of phenyls, 1J(31P–13C) 58.35 Hz), 111.32 (C-4), 110.90
(C-3), 44.01 (–CH2–); assignment was based on the 1H–13C HET-
COR and 1H–1H COSY spectra; 31P–{1H} NMR (DMSO, 162.0 MHz,
85% H3PO4): d 33.17 (s, N–(P–(C6H5)2)2); selected IR (KBr pellet,
Calc. for C29H25ONP2PtCl2 (mw: 731.46 g/mol): C, 47.62; H, 3.45;
N, 1.92. Found: C, 47.54; H, 3.38; N, 1.90%.
2.5.2.5. Synthesis of cis-dimethylbis(furfuryl-(N-diphenylphosphino)
amine)platinum (1c). A solution of [Pt(CH3)2(cod)] (0.100 g,
0.25 mmol) and furfuryl-(N-diphenylphosphino)amine, 1, (0.150 g,
0.51 mmol) in thf (25 mL) was stirred for 1 h. The volume was con-
centrated in vacuum to ca. 1–2 mL and addition of diethyl ether
(15 mL) gave 1c as white solid which was collected by filtration
and dried in vacuum (yield: 0.190 g, 87.5%, mp 64–65 °C). 1H
NMR (CDCl3, 400.1 MHz, Me4Si): d 7.52 (dd, o-hydrogen of phenyls,
8H, 3J 8.00 and 12.40 Hz), 7.44 (t, p-hydrogen of phenyls, 4H, 3J
7.20), 7.32 (t, m-hydrogen of phenyls, 8H, 3J 8.16), 7.20 (d, H-5,
2H, 3J 3.20 Hz), 6.22 (dd, H-4, 2H, 3J 2.46 and 3.20), 5.86 (d, H-3,
2H, 3J 2.46 Hz), 4.31 (m, –NH–, 2H); 3.52 (br, –CH2–, 4H), 1.32
2
(m, –CH3, 6H, J(PtH) 63.50 Hz); 13C NMR (d in ppm rel. to TMS, J
Hz, in CDCl3): d 151.79 (d, C-2, 3J(31P–13C) 4.00 Hz), 141.99 (C-5),
133.37 (t, o-carbons of phenyls, 2J(31P–13C) 6.04 Hz), 131.47 (s,
p-carbons of phenyls), 129.65 ppm (d, i-carbons of phenyls,
1J(31P–13C) 74.07 Hz), 128.34 (d, m-carbons of phenyls,
3J(31P–13C) 5.53 Hz), 111.02 (C-4), 107.78 (C-3), 40.09 (–CH2–),
28.78 (–CH3); assignment was based on the 1H–13C HETCOR and
1H–1H COSY spectra; 31P–{1H} NMR (CDCl3, 162.0 MHz, 85%
in cmꢀ1):
29H25ONP2PdCl2 (mw: 642.79 g/mol): C, 54.19; H, 3.92; N, 2.18.
Found: C, 54.07; H, 3.88; N, 2.15%.
m(P–N–P) 824, m(P–Ph) 1436; Anal. Calc. for
C
2.5.2.3. Synthesis of
cis-dichlorobis(furfuryl-(N-diphenylphos-
phino)amine)platinum(II) (1b). A solution of [PtCl2(cod)] (0.191 g,
0.51 mmol)
and
furfuryl-(N-diphenylphosphino)amine,
1,
1
H3PO4): d 60.07 (s, NH–P–(C6H5)2, J(PtP): 2042.49 Hz); selected IR
(0.287 g, 1.02 mmol) in thf (25 mL) was stirred for 1.5 h. The vol-
ume was concentrated in vacuum to ca. 1–2 mL and addition of
diethyl ether (15 mL) gave 1b as white solid which was collected
by filtration and dried in vacuum (yield: 0.391 g, 92.7%, mp 96–
98 °C). 1H NMR (CDCl3, 400.1 MHz, Me4Si): d 7.55 (dd, o-hydrogen
of phenyls, 8H, 3J 8.00 and 12.00 Hz), 7.45 (t, p-hydrogen of phen-
yls, 4H, 3J 7.00), 7.31 (t, m-hydrogen of phenyls, 8H, 3J 8.16), 7.24
(d, H-5, 2H, 3J 3.40 Hz), 6.21 (dd, H-4, 2H, 3J 2.52 and 3.40), 5.89
(d, H-3, 2H, 3J 2.52 Hz), 4.30 (m, –NH–, 2H); 3.52 (br, –CH2–, 4H);
13C NMR (d in ppm rel. to TMS, J Hz, in CDCl3): d 151.77 (d, C-2,
3J(31P–13C) 4.00 Hz), 141.98 (C-5), 133.37 (t, o-carbons of phenyls,
2J(31P–13C) 6.04 Hz), 131.47 (s, p-carbons of phenyls), 129.65 ppm
(d, i-carbons of phenyls, 1J(31P–13C) 75.45 Hz), 128.34 (d,
m-carbons of phenyls, 3J(31P–13C) 5.53 Hz), 110.28 (C-4), 107.04
(C-3), 40.09 (–CH2–); assignment was based on the 1H–13C
(KBr pellet, in cmꢀ1):
m(P–N) 854, m(P–Ph) 1435, m(N–H) 3227; Anal.
Calc. for C34H32N2O2P2Pt(CH3)2 (mw: 787.736 g/mol): C, 54.89; H,
4.86; N, 3.56. Found: C, 54.76; H, 4.80; N, 3.53%.
2.5.2.6. Synthesis of cis-dimethyl(furfuryl-(N,N-bis(diphenylphos-
phino))amine)platinum (2c). A solution of [Pt(CH3)2(cod)] (0.340 g,
1.02 mmol) and furfuryl-(N,N-bis(diphenylphosphino))amine, 2,
(0.475 g, 1.02 mmol) in thf (25 mL) was stirred for 2 h. The volume
was concentrated in vacuum to ca. 1–2 mL and addition of diethyl
ether (15 mL) gave 2c as white solid which was collected by filtra-
tion and dried in vacuum (yield: 0.622 g, 88.4%, mp 132–134 °C).
1H NMR (DMSO, 400.1 MHz, Me4Si): 1H NMR (d in ppm rel. to
TMS, J Hz, in CDCl3): d 7.86 (dd, o-hydrogen of phenyls, 8H, 3J
6.40 and 12.26 Hz), 7.66 (t, p-hydrogen of phenyls, 4H, 3J 3.54),
7.57 (t, m-hydrogen of phenyls, 8H, 3J 7.00), 7.01 (br, H-5, 1H),
6.11 (br, H-4, 1H), 5.81 (d, H-3, 1H, 3J 2.89 Hz), 3.95 (t, –CH2–,
HETCOR and 1H–1H COSY spectra; 31P–{1H} NMR (CDCl3,
1
162.0 MHz, 85% H3PO4):
3946.26 Hz); selected IR (KBr pellet, in cmꢀ1):
Ph) 1436, (N–H) 3292; Anal. Calc. for C34H32N2O2P2PtCl2 (mw:
d
34.45, (s, NH–P–(C6H5)2, J(PtP)
:
2
m
(P–N) 811,
m(P–
2H, 3J 11.90 Hz), 0.95 (m, –CH3, 6H, J(PtH) 67.90 Hz); 13C NMR (d
m
in ppm rel. to TMS, J Hz, in CDCl3): d 148.67 (C-2), 143.14 (C-5),
133.58 (t, o-carbons of phenyls, 2J(31P–13C) 6.54 Hz), 133.27 (s,
p-carbons of phenyls), 129.42 (d, m-carbons of phenyls,
3J(31P–13C) 10.56 Hz), 126.47 ppm (d, i-carbons of phenyls,
1J(31P–13C) 58.35 Hz), 111.26 (C-4), 110.87 (C-3), 43.87 (–CH2–),
29.28 (–CH3); assignment was based on the 1H–13C HETCOR and
1H–1H COSY spectra; 31P–{1H} NMR (DMSO, 162.0 MHz, 85%
H3PO4): d 50.59, (s, N–(P–(C6H5)2)2, J(PtP): 1546.26 Hz); selected
828.5726 g/mol): C, 49.29; H, 3.89; N, 3.38. Found: C, 49.12; H,
3.85; N, 3.35%.
2.5.2.4. Synthesis of cis-dichloro(furfuryl-(N,N-bis(diphenylphos-
phino))amine)platinum (2b). A solution of [PtCl2(cod)] (0.382 g,
1.02 mmol) and furfuryl-(N,N-bis(diphenylphosphino))amine, 2,
(0.475 g, 1.02 mmol) in thf (25 mL) was stirred for 2 h. The volume
was concentrated in vacuum to ca. 1–2 mL and addition of diethyl
ether (15 mL) gave 2b as pale green which was collected by filtra-
tion and dried in vacuum (yield: 0.680 g, 91.2%, mp 201–203 °C).
IR (KBr pellet, in cmꢀ1):
m(P–N–P) 816, m(P–Ph) 1434; Anal. Calc.
for C29H25ONP2Pt(CH3)2 (mw: 731.46 g/mol): C, 53.91; H, 4.52; N,
2.03. Found: C, 53.77; H, 4.48; N, 2.00%.

M. Aydemir et al. / Inorganica Chimica Acta 378 (2011) 10–18
13
2.5.3. X-ray diffraction analysis
of the P–N bonds in these ligands [31–33]. Furfuryl-2-(N-diphenyl-
phosphino)amine, 1 and furfuryl-2-(N,N-bis(diphenylphosphino)
amine), 2 were prepared from the commercially available starting
materials furfurylamine and 1 or 2 equivalents of Ph2PCl in the pres-
ence of triethylamine by aminolysis [34–37] in thf at 0 °C, respec-
tively (Scheme 1). Compounds 1 and 2 were fully characterized by
multinuclear NMR, infrared spectroscopy and microanalysis. All
the compounds gave reasonable microanalyses results. The 31P–
{1H} NMR spectra of 1 and 2 showed single resonances at d(P)
42.71 and 62.54 ppm, respectively, similar to those found for closely
related compounds [38–40]. Compounds 1 and 2 are not stable and
decompose rapidly on exposure to air or moisture. When the reac-
tions were monitored by 31P NMR spectroscopy, the formation of
P(O)Ph2PPh2 was observed, as indicated by signals at d 35.20 (d)
ppm and d ꢀ25.10 (d) ppm, {1J(PP) 224 Hz}[41–43]. In the 1H NMR
spectrum, the NH resonance of 1 is observed as slightly broad dou-
For the crystal structure determination, the single-crystals of
the complexes 2a and 2b were used for data collection on a four-
circle Rigaku R-AXIS RAPID-S diffractometer (equipped with a
two-dimensional area IP detector). The graphite-monochromated
Mo Ka
radiation (k = 0.71073 Å) and oscillation scans technique
with
D
x = 5° for one image were used for data collection. The lat-
tice parameters were determined by the least-squares methods on
the basis of all reflections with F2 > 2 (F2). H atoms were posi-
r
tioned geometrically and refined using a riding model. Integration
of the intensities, correction for Lorentz and polarization effects
and cell refinement was performed using CrystalClear software
[29]. The structures were solved by direct methods using SHELXS
-
97 and refined by a full-matrix least-squares procedure using the
program SHELXL-97 [30]. The final difference Fourier maps showed
no peaks of chemical significance. Details of the crystal parameters,
data collection and refinement are summarized in Table 1.
blet of triplets at 2.38 ppm due to the multiple coupling of 3JðCH
2NHÞ
2
and J(NHP) and was confirmed by H/D exchange experiments. In
addition, the methylene groups give doublet of doublet at
4.01 ppm (3J 6.80 and 8.80 Hz) and triplet at 4.34 ppm (3J 8.60 Hz)
for 1 and 2, respectively. Furthermore, characteristic J(31P–13C) cou-
pling constants of the carbons of the phenyl rings are observed in the
13C NMR spectra (including i-, o-, m-, p-carbons of phenyl rings, for
details see Section 2), which are consistent with the literature values
[44,45].
3. Results and discussion
3.1. Synthesis and characterization
Although aminolysis of chlorophosphines is an efficient method
for preparing R2PN(H)R0 or (R2P)2NR0 it has not widely been
exploited yet, in part possibly because of the associated instability
The coordination chemistry of the ligands Ph2PNHCH2-C4H3O, 1
and (Ph2P)2NCH2-C4H3O, 2 was studied by forming their palladium
and platinum complexes. Reaction of 1 or 2 with [Pd(cod)Cl2]
(cod = 1,5-cyclooctadiene) give the corresponding Pd(II) complexes
1a and 2a in high yields (ca. 90%). Both of the isolated dichloropal-
ladium(II) complexes 1a and 2a were found to have the cis-configra-
tion, characteristic of phosphines having mutually cis-arrangement
[46–49] (Scheme 1). In the 31P–{1H} NMR spectrum, each of 1a
and 2a gives one signal at 46.05 and 33.17 ppm, respectively,
which are within the expected range of other reported structurally
similar complexes [50–52]. The 13C–{1H} NMR spectrum displays
well-resolved signals for the phenyls carbons [53]. Furthermore,
1H NMR spectral data of the complexes 1a and 2a are consistent
with the structures proposed and the compositions of the two
complexes have been confirmed by elemental analysis. In the IR
spectra, one observes very strong absorption bands at ca. 813 for
Table 1
Details of the crystal parameters, data collection and refinement for complexes 2a and
2b.
Crystal data
2a
2b
Empirical formula
Formula weight
T (K)
[C29H25NP2Cl2Pd]ꢂCH2Cl2 [C29H25NP2Cl2Pt]ꢂCH2Cl2
727.7
816.4
293(2)
0.71073
monoclinic
P21/n
293(2)
Wavelength (Å)
Crystal system
Space group
Unit cell dimensions
a (Å)
0.71073
monoclinic
P21/n
13.2262(2)
12.4866(3)
19.1989(4)
90
13.2659(4)
12.5326(2)
19.2205(6)
90
101.31(3)
90
3133.5(2)
4
1.73
b (Å)
c (Å)
a
(°)
b (°)
101.06(3)
90
3111.8(1)
4
1a and 824 cmꢀ1 for 2a due to the
m(P–N) stretching. In addition,
single crystal of [Pd((Ph2P)2NCH2-C4H3O)Cl2], 2a suitable for X-ray
diffraction study was obtained by slow diffusion of diethyl ether
into solution of the compound in dichloromethane.
c
(°)
V (Å3)
Z
Density (calculated)
1.55
(Mg/m3)
Absorption coefficient
1.068
4.946
The reaction of [Pt(cod)X2] (cod = 1,5-cyclooctadiene; X = Cl,
CH3) with 2 equivalents of 1 affords the formation of complexes
[Pt(Ph2PNHCH2-C4H3O)2X2], (X = Cl 1b, X = CH3 1c), in high yields
as the main products. In both complexes, 1 binds the metal center
as monodentate ligand. The formation of compounds 1b and 1c
was followed by recording the 31P–{1H} NMR spectra giving single
resonances at d 34.45 and 60.07 ppm, respectively, consistent with
the structures of the complexes [54]. The complexes 1b and 1c show
large 1JPtP coupling 3946 and 2042 Hz, respectively, which are char-
acteristic of phosphines having mutually cis-arrangement [55]
(Fig. 1). 1H NMR spectral data of 1b and 1c are consistent with the
structures proposed. Furthermore, in the 13C–{1H} NMR spectra of
1b and 1c, J(31P–13C) coupling constants are measured for the car-
bons of the phenyl rings and they are consistent with the literature
values [56,57]. The IR spectra of 1b and 1c show very strong absorp-
(mmꢀ1
)
F(0 0 0)
Crystal
1464
1592
block; pale green
0.13 ꢁ 0.14 ꢁ 0.21
2.1–26.5
block; pale green
0.10 ꢁ 0.13 ꢁ 0.21
2.3–26.4
Crystal size (mm3)
h-Range for data
collection (°)
Index ranges
ꢀ16 6 h 6 16,
ꢀ15 6 k 6 15,
ꢀ23 6 l 6 23
67 151
ꢀ16 6 h 6 16,
ꢀ15 6 k 6 15,
ꢀ24 6 l 6 22
53 382
Reflections collected
Independent
6401 (0.086)
6420 (0.075)
reflections (Rint
)
Refinement method
full-matrix least-squares full-matrix least-
on F2
squares on F2
5197/353
1.103
Data/parameters
Goodness-of-fit (GOF)
on F2
4280/352
1.034
Final R indices
R1 = 0.065, wR2 = 0.122
R1 = 0.041, wR2 = 0.093
tion bands at ca. 811 and 854 cmꢀ1, respectively, due to
m(PN)
[F2 > 2 (F2)]
r
stretching. PN stretching frequencies are shifted to lower values
compared to that of the free molecule (804 cmꢀ1 for 1). The compo-
sitions of two complexes were also confirmed by elemental analysis.
In the reaction of [Pt(cod)X2] (cod = 1,5-cyclooctadiene; X = Cl,
CH3) with 1 equivalent of 2 in thf solution, cod is replaced by the
R indices (all data)
Extinction coefficient
Largest difference in
peak and hole
R1 = 0.109, wR2 = 0.137
0.00
0.604 and ꢀ0.792
R1 = 0.055, wR2 = 0.107
0.0009
1.938 and ꢀ0.946
(e Åꢀ3
)

14
M. Aydemir et al. / Inorganica Chimica Acta 378 (2011) 10–18
Scheme 1. Synthesis of furfuryl-2-(N-diphenylphosphino)amine, 1 and furfuryl-2-(N,N-bis(diphenylphosphino)amine), 2 and their metal complexes (i) 1 equivalent Ph2PCl,
1 equivalent Et3N, thf; (ii) 2 equivalents Ph2PCl, 2 equivalents Et3N, thf; (iii) 1/2 equivalents [MCl2(cod)]: (M = Pd, 1a or Pt, 1b) or [Pt(CH3)2(cod)]: 1c, thf; (iv) 1 equivalent
[MCl2(cod)]: (M = Pd, 2a or Pt, 2b) or [Pt(CH3)2(cod)]: 2c, thf.
furfuryl-2-(N,N-bis(diphenylphosphino)amine), 2, as bidentate li-
gand yielding the respective [Pt((Ph2P)2NCH2-C4H3O)X2], (X = Cl
2b, X = CH3 2c), complexes 2b and 2c, respectively. 31P–{1H} NMR
spectra of complexes 2b and 2c show singlets at d 19.32 and
50.59 ppm, respectively [58–60]. The large 1J(195Pt–31P) coupling
constants of 3300.84 Hz for 2b and 1546.26 Hz for 2c are indicative
of a cis-arrangement of phosphines around a platinum(II) centers
[61–63] (Fig. 2). As expected, the 1J(195Pt–31P) coupling constant
value of 2c is much lower than that of 2b [62]. The IR spectra show
the atoms Cl(1), Cl(2), P(1), P(2). The MP2Cl2 squares adopt a
cis-configuration, which is consistent with preparation method.
The angles around Pd and Pt atoms (Table 2) deviate significantly
from the values for a regular square-planar coordination mode.
The formation of four-membered chelate ring imposes a consider-
able distortion around the palladium and platinum atoms. The
P(1)–Pt–P(2) angle [72.8(2)°] is acute, whereas the Cl(1)–Pt–Cl(2)
angle is obtuse by more than 3° [93.8(2)°] (see Table 2 for 2a).
The corresponding M–P and M–Cl bond distances (Table 2) are al-
most equal to our previously reported isomorphous [M{(Ph2P)2N-
C6H4-2-CH(CH3)2}Cl2], where M = Pd and Pt)] [58] structures, but
d(Pd–P) bond distances are shorter than the values of complex
[PdLCl2)] [64] (the molecule has crystallographic m symmetry,
with d(Pd–P) = 2.2572(11) and d(Pd–Cl) = 2.3536 Å).
Analysis of the geometric parameters indicates that the coordi-
nation around P atoms are distorted tetrahedral in each of two
structures, with the angles varying from 93.3(2)° to 119.8(2)°.
The spatial requirements of the substituted moieties and the pres-
ence of the chelate ring have an influence on the angular deforma-
tions of these tetrahedrons. Especially, the different orientations of
adsorption bands at 809 for
m
(PNP) and 1436 cmꢀ1 for
(PPh) in 2c. Characteris-
m(PPh) in 2b
and at 816 for
m
(PNP) and 1434 cmꢀ1 for
m
tic JPC coupling constants were observed in the 13C NMR spectra,
which are consistent with the literature values [63]. 1H NMR spec-
tra of the compounds, 2b and 2c, are consistent with the structural
compositions. These complexes could be isolated as analytically
pure solid materials and characterized by elemental analysis. Fur-
thermore, the crystal structure of complex [Pd((Ph2P)2NCH2-
C4H3O)Cl2], 2b was further confirmed by single crystal X-ray
diffraction.
Single crystal X-ray diffraction studies of compounds
[M((Ph2P)2NCH2-C4H3O)Cl2], M = Pd (2a), Pt (2b) were undertaken
to elucidate the coordination sphere of palladium(II) and platini-
um(II) atoms. The molecular structures of palladium(II) and plati-
num(II) complexes with the atomic numbering scheme are
shown in Fig. 3 and selected bond lengths and angles are given
in Table 2. Both complexes crystallize in the monoclinic space
group P21/n containing four formula units and the disordered sol-
vent CH2Cl2 in the unit cell. Structures of complexes 2a and 2b in
the solid state are given Fig. 3. The key bond lengths and angles
of complexes 2a and 2b in the solid state are very similar (see
Table 2).
phenyl rings do not permit the intermolecular
p p stacking inter-
ꢂ ꢂ ꢂ
actions, but the C–Hꢂ ꢂ ꢂ
p
(furan) and C–Hꢂ ꢂ ꢂCl interactions help to
consolidate the packing (details in Table. 3), which are similar to
reported [Pt(CH3)Cl(C25H23N2P)2] structure [65].
3.2. The Suzuki coupling reactions
The palladium-catalyzed cross-coupling of aryl halides with
aryl boronic acids (Suzuki reaction) is one of the most powerful
and popular methods for the construction of unsymmetrical biar-
yls, which are widely used for the synthesis of valuable organic
compounds such as pharmaceuticals and agrochemicals [66].
Although several other cross-coupling reactions are available to
produce biaryls, the Suzuki reaction has widely been used over
the course of the last few years, since it has several advantages
The coordination environments of palladium(II) and plati-
num(II) ions are distorted square-planar, formed by two P atoms
and two Cl atoms. The Pd and Pt atoms are at distance of 0.0375(5)
and 0.0239(4) Å, respectively, from the basal plane defined by

M. Aydemir et al. / Inorganica Chimica Acta 378 (2011) 10–18
15
Fig. 1. The 31P–{1H} NMR spectra of complexes; 1b: cis-dichlorobis(furfuryl-(N-diphenylphosphino)amine)platinum(II), 1c: cis-dimethylbis(furfuryl-(N-diphenylphosphino)-
amine)platinum(II).
Fig. 2. The 31P–{1H} NMR spectra of complexes; 2b: cis-dichloro(furfuryl-(N,N-bis(diphenylphosphino))amine)platinum(II). 2c: cis-dimethyl(furfuryl-(N,N-bis(diphenyl-
phos-phino))amine)platinum(II).
compared with other available methods. One particular advantage
of this reaction is that it can be performed under mild conditions in
aqueous solutions that tolerates a broad range of functional groups
[67]. Boronic acids are generally nontoxic, stable, and environmen-
tally benign, and the boron containing by-products can easily be
removed from the reaction medium after the reaction [68,69].
The palladium complexes 1a and 2a were tested as catalysts in
the Suzuki reaction of aryl bromides with boronic acid [70]. Fol-
lowing optimization experiments we found that the use of
0.01 mmol the palladium complexes (1a, 2a) with Cs2CO3 as the
base at 60 °C in dioxane appeared to be best. We initially tested
the catalytic activity of the complexes (1a, 2a) for the coupling of
p-bromoacetophenone with phenylboronic acid and the control
experiments showed that the coupling reaction does not occur in
the absence of the catalyst. Under these conditions, p-bromoaceto-
phenone, p-bromobenzaldehyde, p-bromobenzene, p-bromoani-
sole and p-bromotoluene react cleanly with phenylboronic acid
in high yields (Table 4).

16
M. Aydemir et al. / Inorganica Chimica Acta 378 (2011) 10–18
Fig. 3. Structures of palladium(II) (2a) and platinum(II) (2b) complexes. Note that both molecules in structures 2a and 2b are asymmetric.
Table 2
Selected bond lengths (Å), bond and torsion angles (°) for the structures of asymmetric 2a and 2b complexes (M = Pd and Pt, respectively).
2a
2b
2a
2b
M–CL(2)
M–P(2)
P(1)–N(1)
P(1)–C(24)
P(2)–C(13)
P(1)ꢂ ꢂ ꢂP(2)
2.357(2)
2.208(3)
1.702(4)
1.798(6)
1.791(6)
2.608(4)
2.357(2)
2.203(2)
1.708(6)
1.804(5)
1.789(6)
2.616(4)
M–P(1)
2.214(2)
2.354(2)
1.789(6)
1.689(5)
1.800(6)
2.203(2)
2.349(2)
1.805(6)
1.699(6)
1.792(7)
M–CL(1)
P(1)–C(2)
P(2)–N(1)
P(2)–C(12)
P(1)–M–CL(2)
P(1)–M–CL(1)
CL(2)–M–CL(1)
M–P(1)–N(1)
M–P(1)–C(2)
N(1)–P(1)–C(2)
M–P(2)–N(1)
93.8(1)
167.3(1)
98.2(1)
93.3(2)
117.9(2)
111.1(3)
93.8(2)
95.9(1)
169.7(1)
93.8(1)
93.3(2)
118.2(3)
110.1(3)
93.6(2)
P(1)–M–P(2)
72.3(1)
166.1(1)
95.7(1)
115.5(2)
111.0(3)
107.4(3)
119.8(2)
72.8(1)
168.7(1)
97.5(1)
116.1(3)
111.4(3)
107.0(4)
119.2(3)
CL(2)–M–P(2)
P(2)–M–CL(1)
M–P(1)–C(24)
N(1)–P(1)–C(24)
C(24)–P(1)–C(2)
M–P(2)–C(12)
Torsion angles (°)
CL(2)–Pd–P(1)–N(1)
CL(2)–Pd–P(1)–C(2)
P(1)–Pd–P(2)–N(1)
P(1)–PD–P(2)–C(12)
178.4
62.4
0.7
CL(2)–Pd–P(1)–C(24)
P(2)–Pd–P(1)–N(1)
P(2)–Pd–P(1)–C(24)
ꢀ66.5
ꢀ0.7
114.5
112.8
CL(2)–Pt–P(1)–N(1)
CL(2)–Pt–P(1)–C(2)
P(1)–Pt–P(2)–N(1)
P(1)–Pt–P(2)–C(12)
ꢀ178.1
ꢀ63.2
ꢀ0.9
CL(2)–Pt–P(1)–C(24)
P(2)–Pt–P(1)–N(1)
P(2)–Pt–P(1)–C(24)
66.1
0.9
ꢀ115.0
ꢀ112.5
Table 3
Hydrogen-bond geometry (Å, °). Cg(1) is the centroid of the furan ring.
D–Hꢂ ꢂ ꢂA
D–H
Hꢂ ꢂ ꢂA
Dꢂ ꢂ ꢂA
<D–Hꢂ ꢂ ꢂA
2a
C(19)–H(19A)ꢂ ꢂ ꢂCg(1)i
0.97
2.76
3.665(7)
155
Symmetry codes: (i) 1 ꢀ x, ꢀy, 1 ꢀ z
2a
C8–H8ꢂ ꢂ ꢂCl(1)i
C10–H10ꢂ ꢂ ꢂCl(2)ii
C30–H30Bꢂ ꢂ ꢂCl(1)i
0.93
0.93
0.97
2.79
2.79
2.78
3.558(6)
3.634(6)
3.647(10)
140
151
149
Symmetry codes: (i) 3/2 ꢀ x, ꢀ1/2 + y, 1/2 ꢀ z; (ii) 1/2 + x, 1/2 ꢀ y, 1/2 + z
2b
C(19)–H(19A)ꢂ ꢂ ꢂCg(1)i
0.97
2.76
3.658(9)
153
Symmetry codes: (i) 1 ꢀ x, 1 ꢀ y, ꢀz
2b
C(8)–H(8)ꢂ ꢂ ꢂCl(1)i
C(10)–H(10)ꢂ ꢂ ꢂCl(2)ii
C(30)–H(30B)ꢂ ꢂ ꢂCl(1)i
0.93
0.93
0.97
2.82
2.80
2.81
3.579(8)
3.656(8)
3.654(13)
140
153
146
Symmetry codes: (i) 1/2 ꢀ x, 1/2 + y, 1/2 ꢀ z; (ii) ꢀ1/2 + x, 1/2 ꢀ y, ꢀ1/2 + z

M. Aydemir et al. / Inorganica Chimica Acta 378 (2011) 10–18
17
Table 4
The Suzuki coupling reactions of aryl bromides with phenylboronic acid.
1a and 2a (0.01 mmol)
B(OH)2
Br
R
R
Cs2CO3 (2 equiv.)
Entry
R
Catalyst
Product
Time
Conversion (%)
Yield (%)
TOF (hꢀ1
)
1
2
4-CH3C(O)–
1a
2a
10 min
10 min
97.2
99.9
96.1
98.7
577
592
C(O)CH3
C(O)H
H
3
4
4-CH(O)–
4-H
1a
2a
10 min
10 min
97.7
99.6
96.0
98.2
576
598
5
6
1a
2a
30 min
30 min
86.4
89.9
84.3
88.0
169
176
7
8
4-CH3O–
4-CH3–
1a
2a
1 h
1 h
66.3
73.1
60.7
65.4
61
65
OCH3
CH3
9
10
1a
2a
1 h
1 h
60.7
65.1
53.9
58.5
54
59
Reaction conditions: 1.0 mmol of p-R-C6H4Br aryl bromide, 1.5 mmol of phenylboronic acid, 2.0 mmol Cs2CO3, 1.0 mmol cat., dioxane 3.0 (mL). Purity of compounds was
checked by NMR and yields are based on arylbromide. All reactions were monitored by GC; 60 °C. for 1a and 2a. TOF = (mol product/mol cat.) ꢁ hꢀ1
.
Table 5
The Heck coupling reactions of aryl bromides with styrene.
1a and 2a (0.01 mmol)
Br
R
+
R
K2CO3 (2 equiv.)
Entry
R
Catalyst
Product
Time
Conversion (%)
Yield (%)
TOF (hꢀ1
)
1
2
4-CH3C(O)–
1a
2a
15 min
15 min
95.2
97.2
93.9
96.4
376
386
C(O)CH3
3
4
4-CH(O)–
4-H
1a
2a
15 min
15 min
94.9
98.6
92.3
96.0
369
384
C(O)H
H
5
6
1a
2a
30 min
30 min
77.5
82.4
75.2
80.8
150
162
7
8
4-CH3O–
4-CH3–
1a
2a
1 h
1 h
60.4
64.0
54.5
58.7
54
59
OCH3
CH3
9
10
1a
2a
1 h
1 h
55.5
59.2
50.2
53.4
50
53
Reaction conditions: 1.0 mmol of p-R-C6H4Br aryl bromide, 1.5 mmol of styrene, 2.0 mmol K2CO3, 1.0 mmol% cat., DMF 3.0 (mL) for 1–2a. Purity of compounds was checked by
NMR and yields are based on arylbromide. All reactions were monitored by GC; 100 °C for 1a and 2a. TOF = (mol product/mol cat.) ꢁ hꢀ1
.
3.3. The Heck coupling reactions
polyfunctional compounds, e.g., dienes, cinnamic esters, and other
variously substituted olefinic compounds, which are primarily ap-
plied as dyes, UV absorbers, and intermediates for pharmaceuti-
cals, agrochemicals, and fragrances [75,76]. The rate of coupling
is dependent on a variety of parameters such as temperature, sol-
vent, base and catalyst loading. Generally, the Heck reaction con-
ducted with tertiary phosphine complexes require high
temperatures (higher than 120 °C) and polar solvents. For the
choice of base, we surveyed Cs2CO3, K2CO3 and KtOBu. Finally,
we found that use of 0.01 mmol cat, 2 equivalents K2CO3 in
DMF at 100 °C for 1a and 2a led to the best conversions. We ini-
tially tested the catalytic activities of 1a and 2a for the coupling
of p-bromoacetophenone with styrene.
The reactions involved in forming carbon–carbon bonds are
unquestionably the most important processes in organic chemis-
try, as they present key steps in the building of more complex
molecules from simple precursors. Among the different methods
used to form carbon–carbon bonds, Pd(0)-mediated reactions
have been widely used because of their selective and versatile
applications [71]. The Pd(0)-catalyzed Heck reaction has been
called ‘one of the true power tools of contemporary organic syn-
thesis’ because of its versatility and broad tolerance of functional
groups [72]. The Pd-catalyzed arylation or vinylation of olefins,
universally referred to as the ‘‘Heck reaction’’, has received
increasing attention in the last decade, as it is a selective method
to form new C–C bonds in a single operational step [73,74]. It
constitutes a powerful and versatile method for the synthesis of
A control experiment indicated that the coupling reaction did
not occur in the absence of 1a and 2a. Under the determined
reaction conditions,
a wide range of aryl bromides bearing

18
M. Aydemir et al. / Inorganica Chimica Acta 378 (2011) 10–18
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electron-donating and electron-withdrawing groups reacted with
styrene, affording the coupled products in good yields. As expected,
electron-deficient bromides were beneficial for the conversions
(Table 5). Using aryl chlorides instead of aryl bromides yielded only
small amount of stilbene derivatives under the conditions em-
ployed to bromides.
4. Conclusion
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In summary, the coordination behavior of ligands 1 and 2 to-
wards palladium(II) and platinum(II) were described. We also
demonstrated the application of palladium complexes of these
aminophosphine ligands as pre-catalyst in the Suzuki coupling
and Heck reactions of aryl halides. Because of the strength of the
Pt–C bonds, Pt(II)-bis(phosphino)amine 1b–c and 2b–c system
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were found to show catalytic activity in both the Suzuki and Heck
coupling reactions of aryl bromides. In both cases, the catalytic
activities of complexes 1a and 2a were found to be higher in reac-
tions of aryl bromides with electron-withdrawing substituent than
those with electron-releasing substituent. The procedure is quite
simple and efficient towards various aryl bromides and does not
require an induction period.
Acknowledgments
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Partial support from Dicle University (Project No.: DÜAPK 05-
FF-27) and Turkish Academy of Sciences is gratefully
acknowledged.
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Appendix A. Supplementary material
CCDC 815246 contains the supplementary crystallographic data
for 2a and 2b. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif. Supplementary data associated with this article
can be found, in the online version, at doi:10.1016/
j.ica.2011.07.056.
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