Aminophosphine ligands: Synthesis, coordination chemistry, and activity of their palladium(II) complexes in Heck and Suzuki cross-coupling reactions

Article abstract of DOI:10.1007/s11243-011-9497-8

The reaction of 4-aminodiphenylamine or 2-aminofluorene with two equivalents of PPh₂Cl in the presence of Et₃N gives new bis(diphenylphosphino)amines N,N-bis(diphenylphosphino)-4-aminodiphenylamine 1 and N,N-bis(diphenylphosphino)-2-

Full text of DOI:10.1007/s11243-011-9497-8

Transition Met Chem (2011) 36:513–520
DOI 10.1007/s11243-011-9497-8
Aminophosphine ligands: synthesis, coordination chemistry,
and activity of their palladium(II) complexes in Heck
and Suzuki cross-coupling reactions
•
Cezmi Kayan Nermin Biricik Murat Aydemir
•
Received: 2 March 2011 / Accepted: 20 April 2011 / Published online: 7 May 2011
Ó Springer Science+Business Media B.V. 2011
Abstract The reaction of 4-aminodiphenylamine or
2-aminofluorene with two equivalents of PPh2Cl in the
presence of Et3N gives new bis(diphenylphosphino)amines
N,N-bis(diphenylphosphino)-4-aminodiphenylamine 1 and
N,N-bis(diphenylphosphino)-2-aminofluorene 2 in good
yields. Oxidation of 1 or 2 with hydrogen peroxide, ele-
mental sulfur or gray selenium affords the corresponding
chalcogen derivatives. The palladium and platinum com-
plexes of these P–N–P donor ligands were prepared by the
reaction of the bis(phosphino)amines with MCl2(cod)
(M = Pd or Pt, cod = cycloocta-1,5-diene). All the new
compounds have been characterized by analytical and
spectroscopic methods, including 1H-31P NMR, 1H-13C
[10, 11], and hydrogenation of olefins [12, 13]. In partic-
ular, palladium complexes containing phosphine ligands
serve as highly active catalysts for the formation of car-
bon–carbon bonds [14].
In recent years, the Heck and Suzuki reactions have
found widespread applications in synthetic organic chem-
istry and materials science [15]. Their popularity stems in
part from their tolerance of many functional groups, which
allows them to be employed in the synthesis of highly
complex molecules [16]. Recently, various bulky and
electron-rich phosphanes have been developed as ligands
to promote the cross-coupling reactions [14, 17]. In our
previous papers, we have shown that aminophosphine and
bis(aminophosphine) palladium(II) complexes can be used
in Heck and Suzuki cross-coupling reactions [18, 19].
In the continuation of our interest in new ligand systems
with different spacers to control the electronic attributes
at phosphorus centers and to explore their coordination
chemistry, we report here the synthesis of two new
bis(phosphino)amine ligands. We have demonstrated that the
palladium(II) complexes of N,N-bis(diphenylphosphino)-4-
aminodiphenylamine 1 and N,N-bis(diphenylphosphino)-2-
aminofluorene 2 offer distinct advantages in catalysis of the
Suzuki and Heck cross-coupling reactions.
1
HETCOR, or H-1H COSY correlation experiments. The
Pd(II) complexes were investigated as catalysts in the
Suzuki and Heck reactions; both showed good catalytic
activity affording high yields of the desired products.
Introduction
Tertiary phosphines have long been used in the design and
synthesis of transition metal catalysts, especially with late
transition metals such as nickel, rhodium, ruthenium,
platinum, and palladium [1]. Applications of such catalysts
include allylic alkylation [2, 3], amination [4, 5], Heck
reaction [6, 7], Suzuki coupling [8, 9], hydroformylation
Results and discussion
Synthesis
Electronic supplementary material The online version of this
article (doi:10.1007/s11243-011-9497-8) contains supplementary
material, which is available to authorized users.
Aminolysis appears to be the most common method used for
the synthesis of phosphinoamines and bis(phosphino)amines
[20]. The bis(phosphino)amine ligands 1 and 2 have been
prepared by aminolysis of Ph2PCl with the commercially
available aromatic amines 4-aminodiphenylamine and
C. Kayan ꢀ N. Biricik (&) ꢀ M. Aydemir
Department of Chemistry, Dicle University,
21280 Diyarbakır, Turkey
e-mail: nbiricik@dicle.edu.tr
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Transition Met Chem (2011) 36:513–520
Scheme 1 Synthesis of the N,N-bis(diphenylphosphino)-4-aminodi-
phenylamine, [(Ph2P)2N–C6H4–NH–C6H5], 1 and N,N-bis(diphenyl-
phosphino)-2-aminofluorene, [(Ph2P)2N–C6H3–CH2–C6H4], 2 ligands
and their chalcogenides; (i) 2 equiv. Ph2PCl, 2 equiv. Et3N, thf; (ii) 2
equiv. aqueous hydrogen peroxide, elemental sulfur or gray selenium,
thf; (iii) 2 equiv. Ph2PCl, 2 equiv. Et3N, thf; (iv) 2 equiv. aqueous
hydrogen peroxide, elemental sulfur or gray selenium, thf
2-aminofluorene, respectively, in the presence of Et3N
(Scheme 1). Since the ligands are unstable and rapidly
decompose upon exposure to air or moisture, triethylamine
hydrogen chloride cannot be separated from them by our
previous method [21], which involves washing the solid
product with water. Moreover, triethylamine hydrogen chlo-
ride is soluble in dichloromethane, rendering this solvent
unsuitable for the present case. The reactions proceeded very
slowly in diethyl ether or toluene, but were complete within
1 h in thf, so we preferred thf as the solvent. The 31P{1H}
NMR spectra of the reaction mixtures of 1 and 2 each display
singlets, at 69.3 and 68.4 ppm, respectively, which were
attributedtotheexpectedbis(phosphino)amines,similartothe
sulfides, and the ones at around 50–51 ppm disappeared
after reflux for 1–2 h, so they were thought to be an
intermediate. The remaining resonances at 68.4 and
68.8 ppm were assigned to the sulfide derivatives of 1b and
2b, respectively. The 31P{1H} NMR spectra of the reaction
mixtures of the selenides also show two singlets; those
at 47–48 ppm disappeared after reflux for 1–2 h, so the
oxidation is a stepwise process. The signals at 69.3 and
69.7 ppm were attributed to the selenide derivatives 1c and
2c, respectively. The 31P{1H} NMR resonances of these
chalcogenides are within the range for similar compounds
[27], and furthermore, in the case of the selenides, there are
1
selenium satellites with a JP–Se of *800 Hz. The P=O
structurally related compounds [22]. The H and 13C{1H}
bonds in 1a and 2a are observed at ca. 1,200 cm-1, while
bands at ca. 650–651 cm-1 are characteristic of the P=S
bonds in 1b and 2b, and bands at 566–567 cm-1 can be
ascribed to the P=Se bond in 1c and 2c. The structures of
1
NMR spectra are also in agreement with the proposed struc-
31Pꢁ
tures. CharacteristicJ 13C couplingconstants of the carbons
of the phenyls rings were observed in the 13C NMR spectra,
consistent with the literature values [23, 24]. The IR spectra
of 1 and 2 display absorptions at around 800–900 cm-1
characteristic of the P–N–P moiety. The absorptions at around
3,300 cm-1 in the IR spectra of 1 and its derivatives are
attributed to N–H bonds. Other pertinent spectroscopic and
analytical data are given in the ‘‘Experimental’’ section.
Oxidation of 1 or 2 with aqueous hydrogen peroxide,
elemental sulfur, or gray selenium in thf gave the corre-
sponding oxides (1a–2a), sulfides (1b–2b), and selenides
(1c–2c), which were characterized by analytical and
spectroscopic methods (Scheme 1). Oxidation of the
ligands with hydrogen peroxide was rapid at ambient
temperature. However, the reaction with elemental sulfur
or gray selenium had to be carried out at elevated tem-
perature since sulfur and selenium are weaker oxidizing
agents than hydrogen peroxide, especially toward phos-
phorus atoms with phenyl groups [25, 26]. The 31P{1H}
NMR spectra of the oxides 1a and 2a display singlets at
23.8 and 24.5 ppm, respectively. There were two singlets
in the 31P{1H} NMR spectra of the reaction media of the
1
the oxidized derivatives were further confirmed by H and
13C{1H} NMR and elemental analysis. The selenium
compounds are liable to decompose, upon exposure to air
[20]; therefore, they were stored under argon.
The coordination chemistry of 1 and 2 with Pd and Pt was
explored. Reaction of 1 and 2 with MCl2(cod) (M = Pd or
Pt, cod = cycloocta-1,5-diene) gave the respective palla-
dium(II) and platinum(II) complexes in high yields
(Scheme 2). The 31P{1H} NMR spectra of the palladium
complexes 1d and 2d display singlets at 35.9 and 35.4 ppm,
respectively, which are shifted to lower frequencies by ca.
33 ppm compared with the free ligand. The 31P{1H} NMR
spectra of the platinum complexes 1e and 2e exhibit singlets
at 21.2 and 21.3 ppm, respectively, accompanied by the
platinum satellites (3335.8 and 3337.1 Hz for 1e and 2e,
respectively), indicative of cis geometry [28, 29]. The
31P{1H} NMR chemical shifts of the complexes are within
the range observed for structurally similar complexes [30].
The IR spectra and microanalyses of the complexes were
also in good agreement with the proposed formulae.
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Transition Met Chem (2011) 36:513–520
515
Scheme 2 Synthesis of metal
complexes of N,N-
bis(diphenylphosphino)-4-
aminodiphenylamine,
[(Ph2P)2N–C6H4–NH–C6H5],
1 and N,N-bis(diphenylph-
osphino)-2-aminofluorene,
[(Ph2P)2N–C6H3–CH2–C6H4],
2; (i) 1 equiv. [MCl2[cod)]
(M = Pd or Pt), thf; (ii) 1 equiv.
[MCl2[cod)] (M = Pd or Pt), thf
Table 1 The Suzuki coupling reactions of aryl bromides with phenylboronic acid
1d or 2d
R
B(OH)2
Br
R
Cs2CO3 (2 equiv.)
Entry
1
R
Cat
Product
Conv.(%)
Yield(%) TOF(h-1
)
1d
2d
1d
2d
1d
2d
46
44
46
45
37
38
98.5
96.2
91.5
88.7
4-CH3C(O)-
4-CH(O)-
C(O)CH3
99.8
98.1
92.5
90.1
2
3
C(O)H
H
75.9
81.9
73.6
75.7
4-H
Reaction conditions: 1.0 mmol of p-R-C6H4Br aryl bromide, 1.5 mmol of phenylboronic acid, 2.0 mmol, Cs2CO3, 0.01 mmol (1%) Pd, dioxane
1
(3.0 mL). Purity of compounds was checked by H NMR, and yields are based on aryl bromide. All reactions were monitored by GC: 80 °C,
2.0 h. TOF = (mol product/mol Cat) 9 h-1. GC-yield using diethyleneglycol-di-n-butylether as internal standard
The Suzuki coupling
phenylboronic acid to give good yields of the expected
products (Table 1).
The palladium complexes 1d and 2d were investigated as
catalysts in the Suzuki reactions between aryl and vinyl
halides with boronic acid. In order to survey the reaction
parameters for the Suzuki reaction, we examined Cs2CO3,
K2CO3, and KtOBu as bases and DMF and dioxane as
solvents. Following optimization experiments, we found
that the reaction performed in dioxane, with Cs2CO3 as
the base at 80 °C appeared to be best. We initially tested
the catalytic activity of the complexes for the coupling of
p-bromoacetophenone with phenylboronic acid. Control
experiments showed that the coupling reaction did not
occur in the absence of the palladium complexes. However,
when the catalyst was added, p-bromoacetophenone,
p-bromobenzaldehyde, and p-bromobenzene reacted with
The Heck coupling
The palladium complexes 1d and 2d were also studied as
catalysts in the palladium-catalyzed coupling of aryl/vinyl
halides with olefins. Generally, when the Heck reaction
is conducted with tertiary phosphine or aminophosphine
complexes, high temperatures ([120 °C) and polar sol-
vents are required. For the choice of base, we surveyed
Cs2CO3, K2CO3, and KtOBu. After screening experiments,
we found that the use of 0.01 mmol (1%) of 1d or 2d
and 2 equivalents of K2CO3 in DMF at 120 °C led to the
best conversion within 1.5 h. We initially tested the
catalytic activity of both complexes for the coupling of
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Transition Met Chem (2011) 36:513–520
Table 2 The Heck coupling reactions of aryl bromides with styrene
1d or 2d
Br
R
+
R
K CO (2 equiv.)
2
3
-1
Entry
1
R
Cat
Product
Conv.(%)
Yield(%) TOF(h
)
1d
2d
1d
2d
1d
2d
62
61
95.1
93.7
91.6
4-CH C(O)-
3
C(O)CH
C(O)H
H
3
92.9
96.6
97.1
94.2
94.7
63
63
53
49
4-CH(O)-
4-H
2
3
79.3
72.9
81.7
78.5
Reaction conditions: 1.0 mmol of p-R-C6H4Br aryl bromide, 1.5 mmol of styrene, 2.0 mmol K2CO3, 0.01 mmol (1%) Pd, DMF (3.0 mL). Purity
of compounds was checked by 1H NMR, and yields are based on arylbromide. All reactions were monitored by GC: 120 °C, 1.5 h. TOF = (mol
product/mol Cat) 9 h-1. GC-yield using diethyleneglycol-di-n-butylether as internal standard
p-bromoacetophenone with styrene. Control experiments
indicated that the coupling reaction did not occur in the
absence of catalyst. Under the determined reaction condi-
tions, several aryl bromides were reacted with styrene,
affording the coupled products in excellent yields. As
expected, electron-deficient bromides were beneficial for
the conversions (Table 2).
i.d. 9 0.25 lm film thickness). The GC parameters were as
follows for the Suzuki reactions: initial temperature, 50 °C;
initial time, hold time (1), 1 min; solvent delay, 3.70 min;
temperature ramp 1, 10 °C/min; final temperature, 150 °C;
hold time (2), 0; temperature ramp 2, 15 °C/min; final tem-
perature, 250 °C; hold time (3), 3; final time, 20.67 min;
injector port temperature, 250 °C; detector temperature,
250 °C; and injection volume, 2.0 lL. The GC parameters
were as follows for the Heck reactions: initial temperature,
50 °C; initial time, hold time (1), 1 min; solvent delay,
5.93 min; temperature ramp 1, 13 °C/min; final temperature,
300 °C; hold time (2), 20.23 min; final time, 40.46 min;
injector port temperature, 250 °C; detector temperature,
250 °C; and injection volume, 2.0 lL.
Experimental
All manipulationswere performed under an inert atmosphere
of dry argon. Solvents were dried using the appropriate
reagents and distilled prior to use. The starting materials
[MCl2(cod)] (M = Pt, Pd) were prepared according to lit-
erature procedures [1, 2]. Other starting materials were
obtained commercially and used as received.
Synthesis of N,N-bis(diphenylphosphino)-4-
aminodiphenylamine, (1)
NMR spectra were obtained on a Bruker Avance 400
spectrometer operating at the appropriate frequencies using
SiMe4 as internal standard for 1H and 13C and 85% H3PO4 as
external standard for 31P spectra. IR spectra were recorded on
a Mattson 1000 ATI UNICAM FTIR spectrometer in the
range 4,000–400 cm-1 in KBr matrix. Elemental analyses
werecarried out usinga Fisons EA 1108CHNS-Oinstrument.
GC analyses were performed on a Hewlett-Packard
6890N gas chromatograph equipped with capillary column
(5% biphenyl, 95% dimethylsiloxane) (30 m 9 0.32 mm 9
0.25 lm). Melting points were determined in capillary tubes
using a Gallenkamp MID 350 BM 2.5 apparatus.
Ph2PCl (1.26 g, 5.42 mmol) was added dropwise to a
solution of 4-aminodiphenylamine (0.50 g, 2.71 mmol)
and Et3N (0.55 g, 5.42 mmol) in thf (25 mL) at room
temperature with vigorous stirring. The reaction mixture
was stirred at room temperature for 1 h, and then, the white
precipitate of Et3N.HCl was filtered off under argon, and
the solvent was removed in vacuum. The light blue solid
residue was washed with cold diethyl ether (5 mL) and
dried in vacuum. Yield: 0.81 g (54. %), mp: 117–119 °C.
1H NMR (ppm, CDCl3): d 6.58 (d, 2H, 3J = 8.6 Hz, H-2),
3
GC analyses were performed on a Hewlett-Packard
6890N instrument equipped with a capillary column
(5% biphenyl, 95% dimethylsiloxane) (30 m 9 0.32 mm
6.70 (d, 2H, J = 8.7 Hz, H-6), 6.91–7.88 (m, 25H, H-3,
H-7, H-8 and o-, m-, p-hydrogens of phenyls), 5.70 (br, 1H,
NH). 13C{1H} NMR (ppm, CDCl3): d 145.6 (C-1), 143.5
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Transition Met Chem (2011) 36:513–520
517
(C-4), 142.0 (d, i-carbons of phenyls, 1J
m-, p-hydrogens of phenyls), 7.85–7.90 (dd, 8H, o-hydro-
gens of phenyls, 3J = 7.6 and 11.4 Hz), 4.07 (br, 1H, NH).
13C{1H} NMR (ppm, CDCl3): d 142.7 (C-1), 141.5 (C-4),
31Pꢁ13C
= 17.5 Hz),
= 11.4 Hz), 131.4
133.4 (t, o-carbons of phenyls, 2J
(s, p-carbons of phenyls), 130.2 (C-5), 129.2 (C-7), 129.7
31Pꢁ13C
140.4 (d, i-carbons of phenyls, 1Jð31
= 127.3 Hz),
132.7 (t, o-carbons of phenyls, 2Jð31
(C-5), 131.4 (s, p-carbons of phenyls), 130.8 (C-7), 129.2
(C-3), 128.0 (t, m-carbons of phenyls, 3J
= 3.1 Hz),
Pꢁ13CÞ
31Pꢁ13C
120.5 (C-8), 117.9 (C-6), 115.4 (C-2), assignment
was based on the 1H-13C HETCOR and 1H-1H COSY
spectra. 31P{1H} NMR (ppm, CDCl3): d 69.3 (s). Selected
IR (t, cm-1): 893 (P–N–P), 1,439 (P–Ph), 3,391 (N–H).
C36H30N2P2 (mw: 552.6 g/mol): calcd. C, 78.3; H, 5.5; N,
5.1; found C, 77.9; H, 5.3; N, 4.9%.
= 4.8 Hz), 132.0
Pꢁ13CÞ
(C-3), 127.8 (t, m-carbons of phenyls, 3Jð31
= 6.6 Hz),
Pꢁ13CÞ
121.0 (C-8), 117.6 (C-6), 117.5 (C-2), assignment was based
on the 1H–13C HETCOR and 1H-1H COSY spectra. 31P{1H}
NMR (ppm, CDCl3): d 23.8 (s). Selected IR (t, cm-1):
895 (P–N–P), 1209 (P=O), 1446 (P–Ph), 3295 (N–H).
C36H30N2P2O2(mw: 584.6 g/mol): calcd. C, 74;0 H, 5.2; N,
4.8; found C, 73.7; H, 5; N 4.6%.
Synthesis of N,N-bis(diphenylphosphino)-2-
aminofluorene, (2)
Ph2PCl (1.28 g, 5.52 mmol) was added dropwise to a
solution of 2-aminofluorene (0.50 g, 2.76 mmol) and Et3N
(0.56 g, 5.52 mmol) in thf (15 mL) at room temperature
with vigorous stirring. The mixture was stirred at room
temperature for 1 h, and then, the white precipitate of
Et3NꢀHCl was filtered off under argon, and the solvent
removed in vacuum. The white solid was washed with cold
diethyl ether (5 mL) and dried in vacuum. Yield: 1.03 g
Synthesis of N,N-bis(diphenyloxophosphino)-2-
aminofluorene, (2a)
Aqueous H2O2 (30%, w/w, 0.04 g, 0.36 mmol) was added
dropwise to a suspension of (2) (0.10 g, 0.18 mmol) in thf
(10 ml), and the mixture was stirred for 2 h at room tem-
perature. The solution was concentrated in vacuum to ca.
1–2 mL, and addition of n-hexane (15 mL) gave 2a as a
light yellow solid which was filtered off and dried in
1
(68%), mp: 123–125 °C. H NMR (ppm, CDCl3): d 6.70–
7.68 (m, 27H, aromatic hydrogens and o-, m-, p-hydrogens
of phenyls), 3.59 (s, 2H, CH2). 13C{1H} NMR (ppm,
1
vacuum. Yield: 0.07 g (64%), mp: 235–237 °C. H NMR
(ppm, CDCl3): d 7.14–7.62 (m, 19H, aromatic hydrogens
and m-,p-hydrogens of phenyls), 7.86 (br, 8H, o-hydrogens
of phenyls), 3.60 (s, 2H, CH2). 13C{1H} NMR (ppm, CDCl3):
d {143.4, 140.8, 139.9, 137.2, 131.4, 126.7, 127.3, 126.7,
125.3, 124.9, 119.9, 119.6 ((C1)-(C11), C13)}, 36.6 (CH2),
2
ð
CDCl3): d 144.9 (d, C-2, J 31Pꢁ13CÞ
= 16.9 Hz), {144.0,
141.4, 140.9, 131.5, 125.5, 124.1, 123.7, 119.4, 118.6
((C-4)-(C-11), C-13)}, 114.0 (d, C-3, 3Jð31
=
Pꢁ13CÞ
= 14.0 Hz), 35.8
11.8 Hz), 111.4 (d, C-1, 3Jð31
Pꢁ13CÞ
= 12.7 Hz, i-carbons of phen-
138.3 (d, 1Jð31
= 129.4 Hz, i-carbons of phenyls),
Pꢁ13CÞ
132.6 (br, o-carbons of phenyls), 131.6 (s, p-carbons of
1
ð
(CH2), 139.0 (d, J 31Pꢁ13CÞ
2
yls), 130.2 (t, Jð31Pꢁ13CÞ
= 7.4 Hz, o-carbons of phenyls),
130.0 (s, p-carbons of phenyls), 127.5 (t, 3Jð31
phenyls), 127.9 (d, 3Jð31
= 6.6 Hz, m-carbons of
Pꢁ13CÞ
=
Pꢁ13CÞ
phenyls), assignment was based on the 1H-13C HETCOR and
1H–1H COSY spectra. 31P{1H} NMR (ppm, CDCl3): d 24.5
(s). Selected IR (t, cm-1): 939 (P–N–P), 1,215 (P=O), 1,440
(P–Ph). C37H29NP2O2 (mw: 581.6 g/mol): calcd. C, 76.4; H
5.0; N, 2.4; found C, 76.0; H, 4.8; N, 2.2%.
8.1 Hz, m-carbons of phenyls), assignment was based on
1
1
the H–13C HETCOR and H–1H COSY spectra. 31P{1H}
NMR (ppm, CDCl3): d 68.4 (s). Selected IR (t, cm-1): 901
(P–N–P), 1,433 (P–Ph). C37H29NP2 (mw: 549.6 g/mol):
calcd. C, 80.9; H, 5.3; N, 2.6; found C, 80.5; H, 5.1; N,
2.4%.
Synthesis of N,N-bis(diphenylthiophosphino)-4-
aminodiphenylamine, (1b)
Synthesis of N,N-bis(diphenyloxophosphino)-4-
aminodiphenylamine, (1a)
A mixture of (1) (0.10 g, 0.18 mmol) and S8 (0.01 g,
0.36 mmol) in thf (15 mL) was refluxed for 5 h. After
cooling, the gray solid was filtered off and dried in vacuum.
Aqueous H2O2 (30%, w/w, 0.04 g, 0.36 mmol) was added
dropwise to a suspension of (1) (0.10 g, 0.18 mmol) in thf,
and the mixture was stirred for 2 h at room temperature. The
solution was concentrated in vacuum to ca. 1–2 mL, and
addition of n-hexane (15 mL) gave 2a as a gray solid, which
was collected by filtration and dried in vacuum. Yield: 0.08 g
(73%), mp: 195–197 °C. 1H NMR (ppm, CDCl3): d 6.63 (d,
2H, 3J = 8.6 Hz, H-2), 6.80 (d, 2H, 3J = 8.2 Hz, H-6), 6.90
(t, 1H, 3J = 7.2 Hz, H-8), 7.18–7.32 (m, 16H, H-3, H-7 and
1
Yield: 0.06 g (55. %), mp: 177–179 °C. H NMR (ppm,
3
CDCl3): d 6.46 (d, 2H, J = 8.4 Hz, H-2), 6.70 (d, 2H,
J = 7.8 Hz, H-6), 6.80 (t, 1H, J = 6.1 Hz, H-8), 6.94–
3
7.43 (m, 16H, H-3, H-7 and m-, p-hydrogens of phenyls),
8.0 (dd, 8H, o-hydrogens of phenyls, 2J = 7.6 Hz and
12.9 Hz), 5.27 (br, 1H, NH). 13C{1H} NMR (ppm, CDCl3):
d 141.4 (C-1), 140.7 (C-4), 132.6 (t, o-carbons of phenyls,
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Transition Met Chem (2011) 36:513–520
116.4 (C-2), assignment was based on the 1H-13C HETCOR
and 1H-1H COSY spectra. 31P{1H} NMR (ppm, CDCl3): d
69.3 (s, 1JP–Se: 794.9 Hz). Selected IR (t, cm-1): 566 (P=Se),
875 (P–N–P), 1,440 (P–Ph), 3314 (N–H). C36H30N2P2Se2
(mw: 710.5 g/mol): calcd. C, 60.9; H, 4.3; N, 3.9; found C,
60.5; H, 4.1; N, 3.7%.
1
2Jð31
carbons of phenyls), 130.3 (s, p-carbons of phenyls), 128.5
= 101.6 Hz, i-
Pꢁ13CÞ = 5.5 Hz), 130.9 (d, Jð31Pꢁ13CÞ
(C-5), 128.2 (C-7), 127.8 (C-3), 126.5 (t, m-carbons of
phenyls, 3Jð31
= 6.7 Hz), 120.3 (C-8), 116.8 (C-6),
Pꢁ13CÞ
115.8 (C-2), assignment was based on the H–13C HET-
COR and 1H-1H COSY spectra. 31P{1H} NMR (ppm,
CDCl3): d 68.4 (s). Selected IR (t, cm-1): 650 (P=S), 875
(P–N-P), 1,440 (P–Ph), 3313 (N–H). C36H30N2P2S2 (mw:
616.7 g/mol): calcd. C, 70.1; H, 4.9; N, 4.5; found C, 69.8;
H, 4.7; N, 4.4%.
1
Synthesis of N,N-bis(diphenylselenophosphino)-2-
aminofluorene, (2c)
A mixture of (2) (0.10 g, 0.18 mmol) and Se (0.03 g,
0.36 mmol) in thf (15 mL) was refluxed for 5 h. After cool-
ing, the gray solid was filtered off and dried in vacuum. Yield:
Synthesis of N,N-bis(diphenylthiophosphino)-2-
aminofluorene, (2b)
1
0.10 g (77%), mp: 187–190 °C. H NMR (ppm, CDCl3): d
7.17–7.78 (m, 19H, aromatic hydrogens and m-, p-hydrogens
of phenyls), 8.14–8.22 (dd, 8H, o-hydrogens of phenyls,
3J = 12.4 Hz and 19.8 Hz), 3.54 (s, 2H, CH2). 13C{1H}
NMR (ppm, CDCl3): d {143.6, 142.5, 140.7, 140.4, 137.0,
129.9, 126.8, 126.7, 124.9, 120.1, 118.9, 116.1 ((C-1)-(C-11),
A mixture of (2) (0.10 g, 0.18 mmol) and S8 (0.01 g,
0.36 mmol) in thf (15 mL) was refluxed for 5 h. After
cooling, the light yellow solid was filtered off and dried in
1
vacuum. Yield: 0.07 g (64.%), mp: 184–187 °C. H NMR
(ppm, CDCl3):d7.15–7.79 (m, 19H, aromatic hydrogens and
m-, p-hydrogens of phenyls), 8.15 (dd, 8H, o-hydrogens of
phenyls, 3J = 6.8 Hz and 13.4 Hz), 3.60 (s, 2H, CH2).
13C{1H} NMR (ppm, CDCl3): d {144.5, 143.5, 142.7, 137.6,
131.3, 126.7, 125.9, 124.9, 120.0, 119.2 (C-2, (C-4)-(C-11),
C-13)}, 118.0 (d, C-3, 3J = 7.1 Hz), 115.9 (d, C-1,
C-13)}, 36.60 (CH2), 136.5 (d, 1Jð31
= 92.2 Hz, i-car-
bons of phenyls), 134.3 (d, 3Jð31
of phenyls), 131.6 (s, p-carbons of phenyls), 127.5 (d,
Pꢁ13CÞ
= 11.7 Hz, o-carbons
Pꢁ13CÞ
3Jð
= 13.9 Hz, m-carbons of phenyls), assignment
was based onthe 1H-13C HETCOR and 1H–1H COSY spectra.
31Pꢁ13CÞ
3J = 6.8 Hz), 36.6 (CH2), 136.5 (d, 1Jð31
i-carbons of phenyls), 133.6 (d, Jð31Pꢁ13CÞ
carbons of phenyls), 128.9 (s, p-carbons of phenyls), 127.5
= 100.5 Hz,
31P{1H} NMR (ppm, CDCl3): d 69.7 (s, JP–Se: 796.0 Hz).
1
Pꢁ13CÞ
Selected IR (t, cm-1): 567 (P=Se), 912 (P–N–P), 1,439
(P–Ph). C37H29NP2Se2 (mw: 707.5 g/mol): calcd. C, 62.8; H,
4.1; N, 1.9; found C, 62.5; H, 3.9; N, 1.8%.
3
= 12.2 Hz, o-
(d, 3Jð31
= 13.8 Hz, m-carbons of phenyls), assign-
Pꢁ13CÞ
ment was based on the 1H-13C HETCOR and 1H-1H COSY
spectra. 31P{1H} NMR (ppm, CDCl3): d 68.8 (s). Selected
IR (t, cm-1): 651 (P=S), 920 (P–N–P), 1,440 (P–Ph).
C37H29NP2S2 (mw: 613.7 g/mol): calcd. C, 72.4; H, 4.8; N,
2.3; found C, 72.0; H, 4.5; N, 2.1%.
Synthesis of dichloro{N,N-bis(diphenylphosphino)-4-
aminodiphenylamine}palladium(II), (1d)
A solution of [Pd(cod)Cl2] (0.05 g, 0.18 mmol) and (1)
(0.10 g, 0.18 mmol) in thf (15 mL) was stirred for 1 h at
room temperature. The volume was reduced to ca. 1–2 mL
under reduced pressure, and addition of diethyl ether
(15 mL) gave 1d as a light brown solid, which was filtered
off and dried in vacuum. Yield: 0.10 g (77%), mp: 279–
281 °C (dec.). 1H NMR (ppm, CDCl3): d 6.31 (d, 2H,
3J = 8.6 Hz, H-3), 6.70 (d, 2H, 3J = 8.8 Hz, H-2), 6.87 (t,
Synthesis of N,N-bis(diphenylselenophosphino)-4-
aminodiphenylamine, (1c)
A mixture of (1) (0.10 g, 0.18 mmol) and Se (0.03 g,
0.36 mmol) in thf (15 mL) was refluxed for 5 h. After
cooling, the gray solid was filtered off and dried in vacuum.
3
3
1H, J = 7.3 Hz, H-8), 7.00 (d, 2H, J = 7.89 Hz, H-6),
7.21 (t, 2H, 3J = 7.8 Hz, H-7), 7.67 (t, 8H, 3J = 6.9 Hz, m-
1
Yield: 0.07 g (54. %), mp: 191–194 °C. H NMR (ppm,
CDCl3): d 6.56 (d, 2H, 3J = 8.7 Hz, H-2), 6.8 (d, 2H,
3
hydrogens of phenyls), 7.78 (t, 4H, J = 7.3 Hz, p-hydro-
3
3J = 8.5 Hz, H-6), 6.91 (t, 1H, J = 7.9 Hz, H-8), 7.06–
7.53 (m, 16H, H-3, H-7 and m-, p-hydrogens of phenyls),
gens of phenyls), 7.84 (dd, 8H, o-hydrogens of phenyls,
3J = 7.6 Hz and 12.6 Hz), 8.36 (br, 1H, NH). 13C{1H}
NMR (ppm, CDCl3): d 144.3 (C-1), 142.2 (C-4), 136.8
3
8.16–8.21 (dd, 8H, o-hydrogens of phenyls, J = 7.9 and
13.8 Hz), 5.45 (br, 1H, NH). 13C{1H} NMR (ppm, CDCl3):
(d, 1Jð31
= 17.0 Hz, i-carbons of phenyls), 134.3 (s, p-
Pꢁ13CÞ
carbons of phenyls), 134.0 (t, o-carbons of phenyls,
d 142.3 (C-1), 141.9 (C-4), 136.3 (d, 1Jð31
i-carbons of phenyls), 134.3 (t, o-carbons of phenyls,
= 92.0 Hz,
Pꢁ13CÞ
2Jð31
= 6.3 Hz), 130.1 (t, m-carbons of phenyls,
= 5.8 Hz), 129.7 (C-7), 128.8 (C-3), 126.9 (C-5),
Pꢁ13CÞ
Pꢁ13CÞ
2Jð31
130.7 (C-5), 129.2 (C-7), 128.6 (C-3), 127.5 (t, m-carbons of
= 11.6 Hz), 131.5 (s, p-carbons of phenyls),
Pꢁ13CÞ
3Jð31
121.6 (C-8), 118.8 (C-6), 115.7 (C-2), assignment was based
3
phenyls, Jð31Pꢁ13CÞ
= 13.7 Hz), 121.4 (C-8), 118.1 (C-6),
123

Transition Met Chem (2011) 36:513–520
519
on the 1H-13C HETCOR and 1H-1H COSY spectra. 31P{1H}
NMR (ppm, CDCl3): d 35.9 (s). Selected IR (t, cm-1): 906
(P–N–P), 1,439 (P–Ph), 3,300 (N–H). C36H30N2P2PdCl2
(mw: 729.9 g/mol): calcd. C, 59.2; H, 4.1; N, 3.8; found C,
58.9; H, 4; N, 3.7%.
3335.8 Hz). Selected IR (t, cm-1): 894 (P–N–P), 1,440 (P–
Ph), 3,326 (N–H). C36H30N2P2PtCl2 (mw: 818.6 g/mol):
calcd. C, 52.8; H, 3.7; N, 3.4; found C, 52.7; H, 3.5; N, 3.2%.
Synthesis of dichloro{N,N-bis(diphenylphosphino)-2-
aminofluorene}platinum(II), (2e)
Synthesis of dichloro{N,N-bis(diphenylphosphino)-2-
aminofluorene}palladium(II), (2d)
A solution of [Pt(cod)Cl2] (0.07 g, 0.18 mmol) and (2)
(0.10 g, 0.18 mmol) in thf (15 mL) was stirred for 1 h at
room temperature. The volume was reduced to ca. 1–2 mL
under reduced pressure, and addition of diethyl ether
(15 mL) gave 2e as a white solid which was filtered off and
dried in vacuum. Yield: 0.08 g (53. %), mp: 251–253 °C
A solution of [Pd(cod)Cl2] (0.05 g, 0.18 mmol) and (2)
(0.10 g, 0.18 mmol) inthf (15 mL) was stirred for 1 h atroom
temperature. The volume was reduced to ca. 1–2 mL under
reduced pressure, and addition of diethyl ether (15 mL) gave
2d asayellowsolidwhichwascollectedbyfiltrationanddried
in vacuum. Yield: 0.09 g (69%), mp: 255–258 °C (dec.). 1H
NMR (ppm, CDCl3): d {6.30 (s, 1H), 6.55 (s, 2H), 7.28–7.67
(m, 16H, aromatic hydrogens and m-, p-hydrogens of phen-
yls}, 7.94 (br, 8H, o-hydrogens of phenyls), 3.62(s, 2H, CH2).
13C{1H} NMR (ppm, CDCl3): d {144.5, 143.2, 141.6, 139.9,
138.3, 127.2, 125.1, 124.3, 123.6, 120.6, 120.2, 116.8 ((C-1)-
1
(dec.). H NMR (ppm, CDCl3): d 7.29–7.68 (m, 19H, aro-
matic hydrogens and m-, p-hydrogens of phenyls), 8.04 (br,
8H, o-hydrogens of phenyls), 3.62 (s, 2H, CH2). 13C{1H}
NMR (ppm, CDCl3): d {144.4, 143.3, 141.5, 140.1, 139.4,
131.2, 127.2, 126.1, 125.1, 124.1, 120.5, 120.2 ((C-1)-(C-
1
11), C-13)}, 136.5 (d, Jð31Pꢁ13CÞ
= 15.6 Hz, i-carbons of
3
= 6.4 Hz, o-car-
ð
phenyls), 36.6 (CH2), 133.8 (t, J 31Pꢁ13CÞ
bons of phenyls), 133.3 (s, p-carbons of phenyls), 129.2 (t,
(C-11), C-13)}, 36.9 (CH2), 137.2 (d, 1Jð31
i-carbons of phenyls), 134.0 (t, Jð31Pꢁ13CÞ
bons of phenyls), 133.5 (s, p-carbons of phenyls), 129.4 (t,
= 14.2 Hz,
Pꢁ13CÞ
= 6.6 Hz, o-car-
3
3Jð31
= 6.3 Hz, m-carbons of phenyls), assignment
was based on the 1H-13C HETCOR and 1H–1H COSY
Pꢁ13CÞ
3Jð31
= 6.3 Hz, m-carbons of phenyls), assignment was
spectra. 31P{1H} NMR (ppm, CDCl3): d 21.3 (s, JPt–P
:
1
Pꢁ13CÞ
1
1
based on the H-13C HETCOR and H-1H COSY spectra.
31P{1H} NMR (ppm, CDCl3): d 35.4 (s). Selected IR (t,
cm-1): 910 (P–N–P), 1,434 (P–Ph). C37H29NP2PdCl2 (mw:
726.9 g/mol): calcd. C, 61.1; H,4.0; N, 1.9; found C, 60.6; H,
3.8; N, 1.7%.
3337.1 Hz). Selected IR (t, cm-1): 903 (P–N–P), 1435 (P–
Ph). C37H29NP2PtCl2 (mw: 815.6 g/mol): calcd. C, 54.5; H
3.6; N 1.7; found C, 54.0; H 3.4; N 1.6%.
General procedure for Suzuki coupling reactions
Synthesis of dichloro{N,N-bis(diphenylphosphino)-4-
aminodiphenylamine} platinum(II), (1e)
Complex (1d) or (2d), (0.01 mmol), aryl bromide
(1.0 mmol), phenylboronic acid (1.5 mmol), Cs2CO3
(2 mmol) and dioxane (3 mL) were placed in a Schlenk
tube under argon, and the mixture was heated at 80 °C for
2.0 h. After the completion of the reaction, the mixture was
cooled and extracted with ethyl acetate/hexane (1:5). The
extract was filtered through a pad of silica gel with copious
washing, concentrated, and purified by flash chromatogra-
phy on silica gel. The purity of the compounds was
A solution of [Pt(cod)Cl2] (0.07 g, 0.18 mmol) and (1)
(0.10 g, 0.18 mmol) in thf (15 mL) was stirred for 1 h at
room temperature. The volume was reduced to ca. 1–2 mL
under reduced pressure, and addition of diethyl ether
(15 mL) gave 1e as a light blue solid which was filtered off
and dried in vacuum. Yield: 0.10 g (67%), mp: [300 °C
(dec.). 1H NMR (ppm, CDCl3): d 6.25 (d, 2H, 3J = 8.0 Hz,
H-6), 6.72 (d, 2H, 3J = 8.2 Hz, H-2), 6.91 (t, 1H,
3J = 7.2 Hz, H-8), 7.00 (d, 2H, 3J = 7.7 Hz, H-3), 7.21 (t,
1
checked by GC and H NMR, and yields are based on the
aryl bromide.
3
2H, J = 7.4 Hz, H-7), 7.66–7.79 (m, 20H), 8.35 (br, 1H,
NH). 13C{1H} NMR (ppm, CDCl3): d 144.2 (C-1), 142.2 (C-
General procedure for Heck reactions
1
Complex (1d) or (2d), (0.01 mmol), aryl bromide
(1.0 mmol), styrene (1.5 mmol), K2CO3 (2 mmol), and
DMF (3 mL) were placed in a Schlenk tube under argon,
and the mixture was heated at 120 °C for 1.5 h. After
completion of the reaction, the mixture was cooled and
extracted with ethyl acetate/hexane (1:5). The extract was
filtered through a pad of silica gel with copious washing,
concentrated, and purified by flash chromatography on
4), 134.5 (d, Jð31Pꢁ13CÞ
134.1 (s, p-carbons of phenyls), 133.8 (t, o-carbons of
= 17.0 Hz, i-carbons of phenyls),
phenyls, 2Jð31
= 6.2 Hz), 129.9 (t, m-carbons of
= 6.0 Hz), 129.7 (C-5), 129.1 (C-7),
Pꢁ13CÞ
phenyls, 3Jð31
127.8 (C-6), 121.5 (C-8), 118.7 (C-3), 115.8 (C-2), assign-
Pꢁ13CÞ
ment was based on the 1H-13C HETCOR and 1H-1H COSY
spectra. 31P{1H} NMR (ppm, CDCl3): d 21.2 (s, JPt–P
1
:
123

520
Transition Met Chem (2011) 36:513–520
2. Wang Y, Guo H, Ding KL (2000) Tetrahedron Asymmetr 11(20):
4153–4162
silica gel. The purity of the compounds was checked by GC
1
and H NMR, and yields are based on the aryl bromide.
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3009–3066
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11. Andrew J, Richard P, Camus JM, Poli R (2002) Inorg Chem
41(15):3876–3885
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tallics 23(23):5524–5529
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14. Punji B, Ganesamoorthy G, Balakrishna MS (2006) J Mol Cat A
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In conclusion, we have synthesized two new bis(phos-
phino)amines and their derivatives including oxides, sul-
fides, selenides, as well as transition metal complexes. The
ligands coordinate in a cis-fashion to both Pd(II) and Pt(II),
as indicated by 31P{1H} NMR spectroscopy. Furthermore,
we have investigated the application of these complexes in
the Suzuki and Heck coupling of aryl bromides. The two
platinum complexes showed no catalytic activity, probably
due to strong Pt–C bonds. In contrast, both palladium
complexes were active catalysts for the Suzuki and Heck
reactions. In both cases, the catalytic activities were higher
in reactions of aryl bromides with electron-withdrawing
substituents than those with electron-releasing substituents.
Following our previous studies that have shown Pd com-
plexes of ether-derivatized aminophosphines to be highly
effective catalysts for C–C cross-coupling reactions [18,
19], we decided to compare catalytic activities of these Pd
complexes with those of the present bis(diphenylphos-
phino)amines (1) and (2). Higher yields of biphenyl were
obtained with 1d and 2d as compared with the other pal-
ladium-bis(phosphino)amine complexes, possessing elec-
tron-donating methoxy substituents. Although the present
ligands are unstable, they can be handled in air. The pal-
ladium and platinum complexes described in this paper are
air-stable, both in the solid state and in solution. All
materials could be handled in air although the coupling
reactions were conducted under an inert atmosphere. In
summary, we have shown that new P–N–P ligands and
their palladium complexes have various advantages, as
follows: (1) the ligands are easily prepared from com-
mercially available and inexpensive starting materials; (2)
the catalysts can be handled in air; (3) reaction times are
reduced and do not require an induction period.
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Gu¨rbu¨z N, Ozdemir I (2010) Inorg Chim Acta 363(5):1039–1047
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Chem 18(6):613–616
22. Burrows AD, Mahon MF, Palmer MT (2000) J Chem Soc Dalton
Trans 1669–1677
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Angew Chem Int Ed 42:783–787
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Acknowledgments Partial support from Dicle University Research
Fund (Project number: DUBAP-06-FF-07) is gratefully acknowledged.
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