Synthesis of new aminophosphine complexes and their catalytic activities in C-C coupling reactions

Article abstract of DOI:10.1016/j.jorganchem.2008.05.010

Two new aminophosphines, benzyl-N(Ph₂P)₂ and 2-picolyl-N(Ph₂P)₂, have been synthesized. Oxidation of the aminophosphines with either hydrogen peroxide, elemental sulfur and selenium gave the corresponding oxides

Full text of DOI:10.1016/j.jorganchem.2008.05.010

Journal of Organometallic Chemistry 693 (2008) 2693–2699
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis of new aminophosphine complexes and their catalytic activities in
C–C coupling reactions
a
a
a
b
b
Nermin Biricik a, , Feyyaz Durap , Cezmi Kayan , Bahattin Gümgüm , Nevin Gürbüz , Ismail Özdemir ,
_
*
Wee Han Ang c, Zhaofu Fei c, Rosario Scopelliti c
a Department of Chemistry, University of Dicle, 21280 Diyarbakir, Turkey
b
_
Department of Chemistry, University of Inönü, 44280 Malatya, Turkey
c Institut de Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
a r t i c l e i n f o
a b s t r a c t
Article history:
Two new aminophosphines, benzyl-N(Ph2P)2 and 2-picolyl-N(Ph2P)2, have been synthesized. Oxidation of
the aminophosphines with either hydrogen peroxide, elemental sulfur and selenium gave the corre-
sponding oxides, sulfides and selenides benzyl-N(Ph2P@E)2 and 2-picolyl-N(Ph2P@E)2, where E = O, S,
or Se. Complexes [benzyl-N(Ph2P)2]MCl2 and [2-picolyl-N(Ph2P)2]MCl2, where M = Pd, Pt, were obtained
by the reaction of the aminophosphines with MCl2(cod). The new compounds were characterised by
NMR, IR spectroscopy and microanalysis. Furthermore, representative solid-state structures of the palla-
dium and platinum complexes were determined using single crystal X-ray diffraction analysis. The pal-
ladium complexes were further investigated as potential catalysts in C–C coupling reactions.
Ó 2008 Elsevier B.V. All rights reserved.
Received 17 March 2008
Received in revised form 6 May 2008
Accepted 6 May 2008
Available online 22 May 2008
Keywords:
Aminophosphine
Synthesis
Oxidation
X-ray structures
Catalysis
1. Introduction
aminophosphine more stable against hydrolysis [12]. The substitu-
ents at the amine backbone can also play an important role in
The chemistry of aminophosphines containing direct P–N bonds
is one of the interesting and challenging areas in the main group
chemistry [1]. Among the numerous aminophosphines,
bis(diphenylphosphino)alkylamine derivatives are particularly
interesting due to their facile synthesis, relatively higher stability
and their ability to chelate transition metals such as palladium,
platinum, copper [2,3]. Functionalized aminophosphines with
additional donor groups attached onto the amine or phosphine
backbones are particularly interesting since the functional group
can be modified to tune the chemical and physical properties of
the final product. Many aminophosphine ligands and their com-
plexes have been investigated as co-catalysts in a number of cata-
lytic processes [4,5]. In addition, some aminophosphines and
derivatives have also been investigated as anticancer drugs [6],
herbicides and antimicrobial agents, as well as neuroactive agents
[7,8].
determining the outcome of the products [13]. In a recent study
[14], we found that electron-donating groups often lead to the
exclusive formation of aminophosphines [PIII–N–PIII], whereas the
electron-withdrawing groups, such as nitrile, trifluoromethyl at
the ortho-position can lead to formation of iminobiphosphine
[PIII–PV@N] species.
The palladium-catalyzed reactions of aryl chlorides with arylbo-
ronic acid (the Suzuki reaction) and with alkenes (the Heck reac-
tion) are among the most common methods for C–C bond
formation and has attracted much current interest [15,16]. Re-
cently, various bulky and electron-rich phosphanes have been
developed as ligands to promote the cross-coupling reaction [17].
The ligands may afford coordinatively unsaturated monophos-
phane-ligated complexes and accelerate the catalytic steps, that
is, oxidative addition, transmetalation, and reductive elimination.
We have shown that N,N-bis(diphenylphosphino)aniline palla-
dium(II) complexes offer distinctive advantages as possible alter-
natives for Pd/phosphine systems in the Heck coupling reactions
[18].
The synthesis of bis(diphenylphosphino)alkylamine is usually
achieved in high yield via the aminolysis method, which allows
the incorporation of additional functional groups such as O- and
N-donors [9,10], or
of the bulky groups attached to the phosphorus center renders the
p
-donors such as ally group [11]. The presence
Herein, we describe the synthesis of new aminophosphines and
corresponding oxides and complexes with selected transition met-
als (Pd,Pt). The compounds were fully characterized using multi-
nuclear NMR spectroscopic methods and the solid-state structure
of the metal complexes was established by single crystal X-ray
* Corresponding author.
E-mail address: nbiricik@dicle.edu.tr (N. Biricik).
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.05.010

2694
N. Biricik et al. / Journal of Organometallic Chemistry 693 (2008) 2693–2699
diffraction analyses. With a view to develop useful catalysts for
C–C coupling reactions, the palladium complexes were further
investigated as potential catalyst precursor for Suzuki-Heck type
coupling reactions.
amine yielded products with single resonances d 62.6 ppm for 1a
and 60.2 ppm for 1b, respectively in their 31P NMR spectra in high
yield. No formation of iminobiphosphine species (Ph2P–
PPh2@NC5H4X, where X = N, CH) was observed. The chemical shift
of compound 1a is shifted downfield with respect to compound 1b,
although they both lie in the expected region of 60–70 ppm [20]. In
the 1H NMR spectra, the aminophosphines displayed overlapped
multiplets in the region of 6.70–8.10 ppm for the aromatic
H-atoms, whereas the CH2 groups lie at 4.69 ppm for 1a and
4.51 ppm for 1b, respectively. Both compounds 1a and 1b are sta-
ble in air, presumably due to the presence of bulky phenyl groups,
and can be washed with water to remove traces of Et3N ꢀ HCl
byproduct. However, in solution, they undergo decomposition in
time.
2. Results and discussions
The new aminophosphines 1a and 1b were prepared from the
commercially available amines via the classical aminolysis reaction
with diphenylphosphine chloride in dichloromethane (see Scheme
1) [19]. The reaction of Ph2PCl with 2-picolylamine and benzyl-
Oxidation of 1a and 1b with either hydrogen peroxide, elemen-
tal sulfur and selenium gave the corresponding oxides 2a and 2b,
sulfides 3a and 3b and selenides 4a and 4b (Scheme 1). As ex-
pected, the oxidation reaction using aqueous H2O2 was very rapid
for both complexes and took place at ambient conditions sponta-
neously, with a small amount of hydrolysis product formed as evi-
denced by the signal at about 20.0 ppm for the Ph2P(O)H in the
31P–{1H} NMR spectra. In contrast, oxidation with sulfur or sele-
nium had to be carried out at elevated temperatures and a step-
wise oxidation process was further observed. For example, in the
sulfurization of 1a, resonances due the starting compound 1a
(62.6 ppm), the mono-oxidized intermediate (62.5 ppm and
72.4 ppm) and the desired product 3a (72.3 ppm) were observed
at the beginning of the reaction. This is not surprising since ele-
mental sulfur and selenium are weaker oxidizing agents than
hydrogen peroxide and that the phosphorous atoms are rendered
less reactive due to the bulky phenyl groups [21,22]. After the com-
pletion of the reaction, the signals of the starting compound 1a and
the mono-oxidized intermediate disappeared leaving the reso-
nance at 72.3 ppm due to the desired product 3a. Attempts to con-
trol the reaction conditions to yield the mono-oxidized
intermediates were unsuccessful.
The 31P NMR spectra of 2a and 2b displayed singlets at
30.6 ppm and 30.3 ppm, respectively, suggesting both phosphorus
atoms are chemically-equivalent in the solution. Similarly, single
resonances were also found in the 31P NMR spectra of 3a and 3b,
at 72.3 ppm and 71.8 ppm, and in those of 4a and 4b, at
71.9 ppm and 72.3 ppm, respectively. The structures of the oxi-
dized derivatives 2a and 2b, sulfides 3a and 3b and selenides 4a
and 4b were further confirmed by using microanalysis and IR spec-
troscopy, and found to be in good agreement with the theoretical
values [23]. It is interesting to note that the 31P NMR chemical shift
of 1a is nearly no different from that of the compound 1b despite
Scheme 1. Synthetic route of N,N-bis(diphenylphosphino)anilines by the aminol-
ysis reaction of H2N–CH2–C5H4X (X = N, CH) with Ph2PCl, and their oxidation and
complexation reactions.
Fig. 1. Ball and stick representation of 5a (left) and 5b (right); atoms of spheres of arbitrary radii. Dichloromethane solvent molecules are omitted for clarity.

N. Biricik et al. / Journal of Organometallic Chemistry 693 (2008) 2693–2699
2695
Fig. 2. Ball and stick representation of 6a (left) and 6b (right); atoms of spheres of arbitrary radii. Dichloromethane solvent molecules are omitted for clarity.
the presence of the pyridyl group in the former. This indicates that
the pyridyl group has little or no electronic influence on the phos-
phorus centre. Same trends were also observed in 2a and 2b, 3a
and 3b, and 4a and 4b.
CH2 groups lie at d 4.30 and 4.24 ppm, slightly upfield (4.69,4.51)
with respect to aminophosphines 1a and 1b.
Single crystals of 5a–6b suitable for X-ray diffraction analysis
were obtained by slow diffusion of diethyl ether into dichloro-
methane solutions of the respective complexes (see Figs. 1 and
2). The crystallographic data are listed in Table 1 and key bond
parameters are given in Table 2. In general, the bond distances
and angles between 5a and 5b and between 6a and 6b in the solid
state are very similar, with minimal structural differences due to
the replacement of the pyridyl group with the phenyl group. Sim-
ilarly, their P–N bond distances are within expected values in com-
parison to similar aminophosphine-transition metal structures
[11–15].
Reactions of 1a and 1b with MCl2(cod) (where M = Pd, Pt;
cod = cyclooctadiene) in dichloromethane gave the corresponding
complexes 5a–6b (see Scheme 1). In both complexes 5a and 6a,
the nitrogen atoms in the pyridyl group were not involved in any
coordination to the metal centres because the phosphorus atoms
in the aminophosphine ligand are much stronger donor centres
and thus, coordination to the metal centre take place preferentially
at the phosphorus atoms.
In the 31P NMR spectra, the chemical shifts of 5a and 5b
34.2 ppm and 34.3 ppm, respectively, are similar and within the
expected range of other reported structurally similar complexes,
where an electron-withdrawing group is attached to the aniline
ring [13–15]. In the 1H NMR spectra, the chemical shifts of the
All 5a–6b complexes form metallacycles, with the aminophos-
phine ligands chelating the metal centre at both phosphine posi-
tions. The metallacycles are nearly planar with P(1)–Pd(1)–P(2)–
N(1) torsion angles of ꢁ4.44(7)° and ꢁ2.57(11)° in 5a and 5b,
Table 1
Crystallographic data for 5a–6b
Chemical formula
5a ꢀ C30H26Cl2N2P2Pd 5b ꢀ 0.5C4H10OC31H27Cl2NP2Pd ꢀ 0.5C4H10
O
6a ꢀ CH2Cl2C30H26Cl2N2P2Pt ꢀ CH2Cl2 6b ꢀ CH2Cl2C31H27Cl2NP2Pt ꢀ CH2Cl2
Formula weight
Crystal system
Space group
A (Å)
B (Å)
C (Å)
653.77
Monoclinic
P21/n
11.9233(17)
18.3698(19)
13.3486(11)
90
108.944(8)
90
2765.4(5)
4
689.84
Monoclinic
P21/n
11.0527(13)
18.3272(12)
15.5888(11)
90
93.534(7)
90
3151.7(5)
4
827.38
Monoclinic
P21/c
9.7892(8)
18.3095(16)
17.9375(11)
90
98.485(6)
90
3179.8(4)
4
826.39
Monoclinic
P21/n
11.0779(9)
18.3443(9)
15.5624(12)
90
94.266(7)
90
3153.8(4)
4
a
(°)
b (°)
(°)
c
Volume (Å3)
Z
Dcalc (g cmꢁ3
F(000)
)
1.570
1320
1.003
1.454
1404
0.885
1.728
1616
4.874
1.740
1616
4.913
l
mmꢁ1
)
T (K)
Wavelength (Å)
Measured reflections
Unique reflections
Unique reflections
100(2)
0.71073
50239
4861
4220
100(2)
0.71073
62809
5548
4360
140(2)
0.71073
18358
5338
140(2)
0.71073
22484
7560
3809
5429
[I > 2r(I)]
No. of data/restraints/
4861/0/334
5548/43/379
5338/0/361
7560/48/361
parameters
Ra[I > 2
r
(I)]
0.0255
0.0509
1.163
0.0396
0.0888
1.127
0.0561
0.1229
1.042
0.0990
0.2059
1.279
a
wR2 (all data)
Goodness-of-fit (GoF)b
P
P
P
P
2
2
1=2
R = jjFoj ꢁ jFcjj/ jFoj, wR2 = f ½wðF2o ꢁ Fc2Þ ꢂ= ½wðFo2Þ ꢂg
.
a
P
GoF ¼ f ½wðF2o ꢁ F2c Þ ꢂ=ðn ꢁ pÞg1=2, where n is the number of data and p is the number of parameters refined.
2
b

2696
N. Biricik et al. / Journal of Organometallic Chemistry 693 (2008) 2693–2699
Table 2
plexes are prepared using bulky phosphine ligands. Since both
Key bond distances (Å) and angles (°) for 5a–6b
complexes 5a and 5b are structurally very similar, it is interest-
ing to compare their catalytical activities in C–C coupling
reactions.
5a
5b
6a
6b
a
M–Pave
2.228
2.365
1.705
2.6146(10)
1.482(3)
71.85(2)
93.88(3)
100.17(11)
ꢁ4.44(7)
2.218
2.370
1.706
2.5920(14)
1.495(5)
71.49(4)
96.75(4)
98.93(17)
ꢁ2.57(11)
2.208
2.360
1.717
2.618(3)
1.475(10)
72.71(9)
92.88(9)
99.4(4)
1.0(3)
2.202
2.358
1.706
2.605(5)
1.492(17)
72.54(13)
92.50(14)
99.6(6)
0.6(4)
a
The Heck reaction has shown to be very useful for the prepara-
tion of disubstituted olefins. The rate of coupling depends on a
variety of parameters such as temperature, solvent, base and cata-
lyst loading. Use of 0.01 mmol, 1% palladium complex, 2 mmol
K2CO3 in dioxane at 80 °C led to the best conversion within 6 h.
We initially evaluated the catalytic activity of palladium com-
plexes for the coupling of 4-bromoacetophenone with styrene (Ta-
ble 3, entry 1). Control experiments indicate that the coupling
reaction did not occur in the absence of 5a or 5b. Under these reac-
tion conditions a wide range of aryl bromides bearing electron-
donating or electron-withdrawing groups react with styrene
affording the coupled products in optimum yields 84–95% (Table
3, entries 1, 2 and 4). Enhancements in activity, although less
significant, are also observed employing 4-bromobenzaldehyde
instead of 4-bromoacetophenone (entries 1, 2).
M–Clave
P–Nave
P(1)–P(2)
N(1)–C(1)
P(1)–M–P(2)a
Cl(1)–M–Cl(2)a
P(1)–N(1)–P(2)
P(1)–M–P(2)–N(1)a
a
M = Pd for 5a and 5b; M = Pt for 6a and 6b.
and P(1)–Pt(1)–P(2)–N(1) torsion angles of 1.0(3)° and 0.6(4)° in 6a
and 6b, respectively. The P–Pd–P angles in 5a and 5b of 71.85(2)°
and 71.48(3)° are slightly smaller than that of P–Pt–P angles in 6a
and 6b of 72.71(9)° and 72.54(13)°, presumably due to the smaller
size of the palladium atom compared to that of the platinum.
In order to survey the parameters for the Suzuki reaction, we
chose to examine Cs2CO3, K2CO3, and K3PO4 as base and dioxane
as the solvent, found that the reactions performed in dioxane with
Cs2CO3 at 80 °C appeared to be best. We started our investigation
with the coupling of 4-bromooacetophenone and phenylboronic
acid, in the presence of complexes (5a, 5b). Table 4 summarizes
the results obtained in the presence of 5a, 5b (Table 4, entries
1–4). The scope of the cross-coupling reaction with respect to the
aryl bromide component was also investigated. It can be seen that
5b is an effective complex for the coupling of unactivated, acti-
vated and deactivated bromides.
3. Catalysis
Palladium complexes in general can be used as catalyst-pre-
cursors in a number of C–C coupling reactions [24,25]. In a real
catalytic process, the palladium complexes are believed to be re-
duced to zero-valent palladium which in many cased are nano-
sized particles that can direct interact with the substrate [26].
The catalytic activities of the complexes depend largely on the
ability of the ligands to activate and stabilize the zero-valent pal-
ladium nanoparticles. For this purpose, many palladium com-
Table 3
Catalytic activity of palladium complex in C–C coupling reactionsa
Entry
R
Yield (%)
5a
5b
1
2
3
4
5
COCH3
CHO
H
OCH3
CH3
41
39
31
37
9
95
84
55
85
17
a
Reaction conditions: 1.0 mmol of R-C6H4X-p, 1.5 mmol of styrene, 2 mmol K2CO3, 1 mmol% Pd complex, dioxane (3 mL) at 80 °C. Reaction time was 6 h with the exception
of entry 4 which was 16 h. Reactions were monitored by GC. Purity of compounds was checked by NMR and yields are based on aryl bromide.
Table 4
Catalytic activity of palladium complex in C–C coupling reactionsa
Entry
R
Yield (%)
5a
5b
1
2
3
4
COCH3
CHO
OCH3
H
94
74
94
88
93
86
89
90
a
Reaction conditions: 1.0 mmol of R-C6H4Br-p, 1.5 mmol of phenylboronic acid, 2 mmol Cs2CO3, 1 mmol% Pd complex, dioxane (3 mL) at 80 °C, 2 h. Purity of compounds
was checked by NMR and yields are based on aryl bromide. All reactions were monitored by GC.

N. Biricik et al. / Journal of Organometallic Chemistry 693 (2008) 2693–2699
2697
The solution was evaporated to dryness under reduced pressure to
yield 3a as a white solid (yield: 0.09 g, 43%; m.p.: 115–117 °C). 1H
NMR (CDCl3) d (ppm): 6.99–7.83 (m, 24H, ArH); 4.64 (s, 2H, CH2);
4. Conclusion
In conclusion, we have prepared two aminophosphines and
their derivatives including oxides, sulfides, selenides, as well as
transition–metal complexes containing Pd, Pt centres. All these
new compounds were characterized using NMR and IR spectros-
copy, with two representative structures studied by single crystal
X-ray diffraction analysis. Although the substituents on the amines
are different, they exhibit similar reactivities towards different oxi-
dants due to the presence of the bulky diphenyl groups at the
phosphorus atom. In addition, they also show similar coordination
properties towards Pd and Pt. However, they show different cata-
lytic activities in C–C coupling reactions. The palladium complexes
exhibit high catalytic activity in the C–C coupling reactions. The
procedure is simple and efficient towards various aryl bromides
and does not require induction period.
31P–{1H} NMR (CDCl3) d (ppm): 30.6 (s). Selected IR,
m
(cmꢁ1): 861
(P–N–P), 1201 (P@O). Anal. Calc. for C30H26N2P2 O2: C, 70.86; H,
5.15; N, 5.51. Found: C, 70.66; H, 5.48; N, 5.23%.
5.4. Synthesis of 2b
A thf solution (10 mL) of 1b (0.20 g, 0.421 mmol) and aqueous
H2O2 (30% w/w, 0,085 mL) was stirred for 2 h at room temperature.
The solution was evaporated to dryness under reduced pressure to
yield 2b as a white solid (yield: 0.082 g, 41%; m.p.: 118–119 °C). 1H
NMR (CDCl3) d (ppm): 7.09–7.79 (m, 25H, ArH); 4.44 (s, 2H, CH2);
31P–{1H} NMR (CDCl3) d (ppm): 30.3 (s). Selected IR,
m
(cmꢁ1): 843
(P–N–P), 1206 (P@O). Anal. Calc. for C31H27NP2O2: C, 73.37; H,
5.36; N, 2.76. Found: C, 73.68; H, 5.86; N, 2.35%.
5. Experimental
5.5. Synthesis of 3a
All reactions were performed under argon unless otherwise sta-
ted. Ph2PCl, 2-picolylamine and benzylamine were purchased from
Fluka and used directly without further purification. PdCl2(cod)
and PtCl2(cod) were prepared according to literature procedures
[27,28]. Solvents were dried using the appropriate reagents and
distilled prior to use. Infrared spectra were recorded as KBr pellet
in the range 4000–400 cmꢁ1 on a Mattson 1000 ATI UNICAM FT-
IR spectrometer. 1H NMR spectra (400 MHz) and 31P–{1H} NMR
spectra (162 MHz) on a Bruker Avance 400 spectrometer. The 1H
NMR spectra were calibrated using residual undeuterated solvent
peaks whereas the 31P–{1H} NMR spectra were externally cali-
brated using 85% H3PO4 solution. Microanalysis was carried out
on a Fisons EA 1108 CHNS-O instrument.
Ligand 1a (0.20 g, 0.420 mmol) and S8 (0.027 g, 0.840 mmol)
were refluxed in thf (20 mL) for 6 h. The reaction mixture was con-
centrated to ca. 1–2 mL in vacuo and n-hexane (20 mL) was added.
The precipitate was filtered and dried in air to yield 3a as a white
solid (yield: 0.1 g, 46%; m.p.: 147–148 °C). 1H NMR (CDCl3) d
(ppm): 6.89–8.06 (m, 24 H, Ar H); 4.72 (s, 2H, CH2); 31P–{1H}
NMR (CDCl3) d (ppm): 72.3 (s). Selected IR,
P), 650 (P–S). Anal. Calc. for C30H26N2P2 S2: C, 66.65; H, 4.81; N,
5.18; S, 11.86. Found: C, 66.43; H, 5.44; N, 5.46; S, 11.08%.
m
(cmꢁ1): 822 (P–N–
5.6. Synthesis of 3b
5.1. Synthesis of 1a
Ligand 1b (0.20 g, 0.421 mmol) and S8 (0.027 g, 0.842 mmol)
were refluxed in thf (20 mL) for 6 h. The reaction mixture was con-
centrated to ca. 1–2 mL in vacuo and n-hexane (20 mL) was added.
The precipitate was filtered and dried in air to yield 3b as a white
solid (yield: 0.17 g, 75%; m.p.: 99–100 °C). 1H NMR (CDCl3) d
(ppm): 6.96–8.01 (m, 25 H, Ar H); 4.62 (s, 2H, CH2); 31P–{1H}
NMR (CDCl3) d (ppm): 71.8 (s). Selected IR,
P), 650 (P–S). Anal. Calc. for C31H27NP2S2: C, 69.00; H, 5.04; N,
2.60; S, 11.88. Found: C, 69.43; H, 5.13; N, 2.49; S, 11.12%.
Ph2PCl (4.10 g, 18.5 mmol) was added slowly to a solution of 2-
picolylamine (1.00 g, 9.25 mmol) and Et3N (1.867 g, 18.5 mmol) in
CH2C12 (30 mL) at 0 °C. The resulting white suspension was stirred
for 3 h, and the solvent was removed under reduced pressure. The
solid was washed with degassed water (3 ꢃ 10 mL) and dried in air
to yield 1a as a white solid (yield: 4.30 g, 98%; m.p.: 160–162 °C).
1H NMR (CDCl3) d (ppm): 6.66–8.41 (m, 24H, Ar–H), 4.69 (s, 2H,
CH2). 13C{1H} NMR (CDCl3) d (ppm): (CArm, 159.8; 148.6; 139.2;
m
(cmꢁ1): 822 (P–N–
135.7; 132.8; 128.8; 128.1; 121.5), (CCH , 57.9). 31P–{1H} NMR
(CDCl3) d (ppm): 62.6 (s). Selected IR,
2
5.7. Synthesis of 4a
m
(cmꢁ1): 855 (P–N–P). Anal.
Calc. for C30H26N2P2: C, 75.62; H, 5.5; N, 5.88. Found: C, 75.46; H,
5.25; N, 5.31%.
Ligand 1a (0.20 g, 0.420 mmol) and elemental Se (0.066 g,
0.840 mmol) were refluxed in thf (20 mL) for 6 h. The reaction mix-
ture was concentrated to ca. 1–2 mL in vacuo and n-hexane (20 mL)
was added. The precipitate was filtered and dried in air to yield 4a
as a white solid (yield: 0.123 g, 45%; m.p.: 283–285 °C). 1H NMR
(CDCl3) d (ppm): 6.89–7.79 (m, 24 H, Ar H); 4.81 (s, 2H, CH2);
5.2. Synthesis of 1b
Ph2PCl (4.10 g, 18.5 mmol) was added slowly to a solution of
benzyl amine (1.00 g, 9.33 mmol) and Et3N (1.867 g, 18.5 mmol)
in CH2C12 (30 mL) at 0 °C. The resulting white suspension was stir-
red for 1 h, and the solvent was removed under reduced pressure.
The residue was washed with degassed water (3 ꢃ 10 mL) and
dried in air to yield 1b as a white solid (yield: 3.67 g, 82%; m.p.:
144–146 °C). 1H NMR (CDCl3) d (ppm): 6.78–7.40 (m, 25H, Ar H),
4.51 (s, 2H, CH2). 13C NMR (CDCl3)d (ppm): (CArm, 139.8; 139.5;
139.3; 132.9; 132.8; 128.8; 128.1; 127.9), (CCH2, 56.1). 31P–{1H}
31P–{1H} NMR (CDCl3) d (ppm): 72, J(PSe): 776 Hz. Selected IR,
m
(cmꢁ1): 817 (P–N–P), 566 (P@Se). Anal. Calc. for C30H26N2P2 Se2:
C, 56.8; H, 4.13; N, 4.42. Found: C, 56.39; H, 4.36; N, 4.31%.
5.8. Synthesis of 4b
Ligand 1b (0.20 g, 0.421 mmol) and elemental Se (0.064 g,
0.842 mmol) were refluxed in thf (20 mL) for 6 h. The reaction mix-
ture was concentrated to ca. 1–2 mL in vacuo and n-hexane (20 mL)
was added. The precipitate was filtered and dried in air to yield 4b
as a white solid (yield: 0.14 g, 53%; m.p.: 151–153 °C). 1H NMR
(CDCl3) d (ppm): 6.95–8.07 (m, 25 H, Ar H); 4.73 (s, 2H, CH2);
31P–{1H} NMR (CDCl3) d (ppm): 72.34, J(PSe): 772 Hz. Selected IR,
NMR (CDCl3) d (ppm): 60.2 (s). Selected IR,
m
(cmꢁ1): 835 (P–N–
P). Anal. Calc. for C31H27NP2: C, 78.32; H, 5.72; N, 2.95. Found: C,
78.61; H, 5.76; N, 3.11%.
5.3. Synthesis of 2a
m
(cmꢁ1): 822 (P–N–P), 522 (P–Se). Anal. Calc. for C31H27NP2Se2:
C, 58.78; H, 4.30; N, 2.21. Found: C, 58.01; H, 4.34; N, 2.33%.
A thf solution (10 mL) of 1a (0.20 g, 0.420 mmol) and aqueous
H2O2 (30% w/w, 0.085 mL) was stirred for 2 h at room temperature.

2698
N. Biricik et al. / Journal of Organometallic Chemistry 693 (2008) 2693–2699
5.9. Synthesis of 5a
7. General procedure for the Suzuki coupling reaction
A
solution of [PdCl2(cod)] (0.050 g, 0.175 mmol) and 1a
Aminophosphine–palladium complexes (5a, 5b, 0.01 mmol, 1%),
aryl bromide (1.0 mmol), phenylboronic acid (1.5 mmol), Cs2CO3
(2 mmol), dioxane (3 mL) were added to a small Schlenk tube in
air and the mixture was heated to 80 °C for 2 h. At the completion
of the reaction, the mixture was cooled, extracted with ethyl ace-
tate/hexane (1:5), filtered through a pad of silicagel with copious
washings, concentrated and purified by flash chromatography on
silica gel. The purity of the compounds was checked by GC and
NMR and yields are based on aryl chloride.
(0.083 g, 0.175 mmol) in CH2Cl2 (10 mL) was stirred for 1.5 h.
The reaction mixture was concentrated to ca. 1–2 mL in vacuo
and diethyl ether (20 mL) was added. The yellow precipitate
was filtered and dried in vacuo to give 5a (yield: 0.082 g, 75%;
m.p.: >300 °C). 1H NMR (CDCl3) d (ppm): 6.31–8.09 (m, 24 H,
Ar H); 4.30 (s, 2H, CH2); 31P–{1H} NMR (CDCl3) d (ppm): 34.2
(s). Selected IR,
30H26N2P2 PdCl2: C, 55.11; H, 4.01; N, 4.28. Found: C, 55.56;
m
(cmꢁ1): 817 (P–N–P). Anal. Calc. for
C
H, 4.27; N, 4.48%.
8. Structure determination in the solid-state
5.10. Synthesis of 5b
Relevant details on the structural refinement are given in Table
1. Data collection for 5a and 5b was performed a Bruker Nonius
APEX II CCD at 100(2) K and data reduction using EvalCCD, while
data for 6a and 6b was collected on a four-circle Kappa goniometer
equipped with an Oxford Diffraction KM4 Sapphire CCD at 140(2) K
and data reduction performed using CRYSALIS RED [29]. Structural
solution was performed using SIR97 [30], structural refinement
using the SHELXTL software package [31], and graphical representa-
tions of the structures were made with Diamond [32]. The struc-
tures were solved by Direct methods and refined by full-matrix
least-squares refinement (against F2), with all non-hydrogen atoms
refined anisotropically. The hydrogen atoms were placed in their
geometrically generated positions using the riding model and re-
fined isotropically. Empirical absorption corrections for 5a and
5b were applied using SADABS and for 6a and 6b using DELABS [33]. Re-
straints were applied on the disordered diethyl ether solvent mol-
ecule in 5b and the phenyl rings in 6b using the SIMU and DELU
A
solution of [PdCl2(cod)] (0.050 g, 0.175 mmol) and 1b
(0.083 g, 0.175 mmol) in CH2Cl2 (10 mL) was stirred for 1.5 h. The
reaction mixture was concentrated to ca. 1–2 mL in vacuo and
diethyl ether (20 mL) was added. The yellow precipitate was fil-
tered and dried in vacuo to give 5b (yield: 0.090 g, 82%; m.p.:
293-295 °C). 1H NMR (CDCl3) d (ppm): 6.50–7.85 (m, 25 H, Ar H);
4.24 (s, 2H, CH2); 31P–{1H} NMR (CDCl3) d (ppm): 34.3 (s). Selected
IR, m
(cmꢁ1): 803 (P–N–P). Anal. Calc. for C31H27NP2PdCl2: C, 57.03;
H, 4.17; N, 2.15. Found: C, 57.37; H, 4.28; N, 2.00%.
5.11. Synthesis of 6a
A
solution of [PtCl2(cod)] (0.032 g, 0.0860 mmol) and 1a
(0.041 g, 0.0860 mmol) in CH2Cl2 (10 mL) was stirred for 1.5 h.
The reaction mixture was concentrated to ca. 1–2 mL in vacuo
and diethyl ether (20 mL) was added. The white precipitate
was filtered and dried in vacuo to give 6a (yield: 0.053 g, 83%;
m.p.: >300 °C). 1H NMR (CDCl3) d (ppm): 6.94–8.11 (m, 24H, Ar
H); 4.23 (s, 2H, CH2); 31P–{1H} NMR (CDCl3) d (ppm): 20.2,
commands implemented in SHELXTL
.
Acknowledgement
J(PtP): 3308 Hz. Selected IR,
for 30H26N2P2 PtCl2: C, 48.53; H, 3.53; N, 3.77. Found: C,
m
(cmꢁ1): 810 (P–N–P). Anal. Calc.
C
We would like to thank Dicle University Reasearch Fund (Pro-
ject no: DÜAPK-05-FF-19 and DÜBAP-06-FF-07) for financial
support.
48.45; H, 3.67; N, 3.88%. Slow diffusion of diethyl ether into a
CH2Cl2 solution of 6a over 48 h gave crystals suitable for X-ray
crystallography.
Appendix A. Supplementary material
5.12. Synthesis of 6b
CCDC 651937, 651938, 651939, and 651940 contains the sup-
plementary crystallographic data for this paper. These data can
be obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
A
solution of [PtCl2(cod)] (0.032 g, 0.0860 mmol) and 1b
(0.041 g, 0.0860 mmol) in CH2Cl2 (10 mL) was stirred for 1.5 h.
The reaction mixture was concentrated to ca. 1-2 mL in vacuo
and diethyl ether (20 mL) was added. The white precipitate was fil-
tered and dried in vacuo to give 6b (yield: 0.048 g, 76%; mp:
>300 °C). 1H NMR (CDCl3) d (ppm): 6.51–0.83 (m, 25H, Ar H);
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