Palladium and nickel complexes of (P,N)-ligands based on quinolines: Catalytic activity for polymerization and oligomerization

Article abstract of DOI:10.1016/j.jorganchem.2005.11.059

Four (P,N)-ligands (1-4) with different steric and electronic properties were synthesized. They were used to prepare the monocationic palladium complexes [Pd(P,N)(CH₃)(NCCH₃)](PF₆) (9-12). The structures of the newly prepared ligand 3 and the neutral palladium complex [Pd(P,N)(CH₃)Cl] (10) were analysed by X-ray. The catalytic activity of the palladium complexes toward the copolymerization of styrene and ethylene with CO was low or non-existent. The nickel complexes [Ni(P,N)(1-naphthyl)Cl] (13-16), modified with the ligands 1-4, were prepared and their catalytic activity toward ethylene oligomerization was studied. They showed high activity at ambient temperature and low ethylene pressure (1-12 bar) in the presence of MAO.

Full text of DOI:10.1016/j.jorganchem.2005.11.059

Journal of Organometallic Chemistry 691 (2006) 1143–1150
www.elsevier.com/locate/jorganchem
Palladium and nickel complexes of (P,N)-ligands based on
quinolines: Catalytic activity for polymerization and oligomerization
a
a,
b
Doina Sirbu , Giambattista Consiglio *, Sebastian Gischig
a
Eidgeno¨ssische Technische Hochschule, Institut fu¨r Chemie und Bioingenieurwissenschaften, Ho¨nggerberg,
Wolfgang-Pauli-Strasse 10, CH-8093 Zu¨rich, Switzerland
Eidgeno¨ssische Technische Hochschule, Laboratorium fu¨r Anorganische Chemie, Ho¨nggerberg, CH-8093 Zu¨rich, Switzerland
b
Received 13 June 2005; received in revised form 16 November 2005; accepted 17 November 2005
Available online 4 January 2006
Abstract
Four (P,N)-ligands (1–4) with different steric and electronic properties were synthesized. They were used to prepare the monocationic
palladium complexes [Pd(P,N)(CH3)(NCCH3)](PF6) (9–12). The structures of the newly prepared ligand 3 and the neutral palladium
complex [Pd(P,N)(CH3)Cl] (10) were analysed by X-ray. The catalytic activity of the palladium complexes toward the copolymerization
of styrene and ethylene with CO was low or non-existent. The nickel complexes [Ni(P,N)(1-naphthyl)Cl] (13–16), modified with the
ligands 1–4, were prepared and their catalytic activity toward ethylene oligomerization was studied. They showed high activity at ambient
temperature and low ethylene pressure (1–12 bar) in the presence of MAO.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Quinoline; (P,N)-ligands; Palladium; Nickel; Oligomerization; Ethylene
1. Introduction
we focused on the design of efficient chelating (P,N)-
ligands to modify the environment around the palladium
or nickel center, based on their electronic and steric effects
as mixed-donor ligands. We report the preparation of four
(P,N)-ligands, 1–4, based on quinoline, each having a
unique set of steric and electronic properties. Our aim
was to determine how these properties are reflected in the
activity of their palladium [Pd(P,N)(CH3)(NCCH3)](PF6)
(9–12) complexes toward copolymerization of styrene and
ethylene with CO. The nickel complexes [Ni(P,N)(1-naph-
thyl)Cl] (13–16), modified with the ligands 1–4, were also
synthesized and their activity toward the oligomerization
of ethylene was studied.
Unsymmetrical bidentate ligands with a nitrogen and
phosphorous donor atom, referred to as (P,N)-ligands,
can chelate a metal center or bridge two identical or two
different metal centers. Owing to their bonding versatility
and the relative ease with which the electronic and steric
properties of the donor atoms can be modified, (P,N)-
ligands play an important role in the coordination chemis-
try of transition metals as well as in homogeneous catalysis
[1–9]. Despite their widespread applications in asymmetric
catalysis, the (P,N)-ligands, and especially those based on
quinoline, have only recently begun to attract attention
with respect to the late-transition-metal-catalyzed oligo-
merization, polymerization and copolymerization reactions
of olefins [10–16]. These studies have demonstrated that the
architecture of the ligand plays an important role in adapt-
ing the activity of the coordinated metal center. Therefore,
2. Results and discussion
2.1. Synthesis of the (P,N)-ligands
One way of changing the properties of the (P,N)-
ligands is to change the substituents on the phosphorus
atom. Therefore, we synthesized four ligands with the
*
Corresponding author. Tel.: +41 1 63 23552; fax: +41 1 63 21162.
E-mail address: consiglio@chem.ethz.ch (G. Consiglio).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.11.059

1144
D. Sirbu et al. / Journal of Organometallic Chemistry 691 (2006) 1143–1150
N
N
P
N
N
P
O
O
P
P
O
O
N
N
N
N
3
4
2
1
Chart 1.
8-substituted quinoline as a backbone, each having a dif-
ferent set of steric and electronic properties (Chart 1).
The phosphonito,N-ligands, 8-(3,5-dioxa-4-phospha-
cyclohepta[2,1-a; 3,4-a0] dinaphtalen-4-yl)-quinoline (1)
and 8-(1,3-dioxa-2-phospha-dibenzo[a,c]cyclohepten-2-yl)-
quinoline (2), were prepared by means of one-pot two-step
synthesis [11]. The first step is the trans-metallation at
183 K of 8-bromo-quinoline with n-BuLi and subsequent
reaction with PCl(NEt2)2, leading to the key intermediate
8-(bis-diethylamino-phosphine)-quinoline. The second step
is the addition of either (R)-binaphtol or 2,20-dihydroxybi-
phenyl, leading to the ligands 1 and 2, with 76% and 57%
yield, respectively (Scheme 1).
were the lithiation of the 8-bromo-quinoline at 183 K and
the addition of the chlorophosphine derivative. The evolu-
tion of the reaction was monitorized by in situ 31P NMR
spectroscopy. After 3 h, the signal of the initial phosphine
at 163 ppm was replaced by the single resonance of the
product, observed at 77.5 ppm. The work-up procedures,
carried out in an inert atmosphere, led to a toluene solu-
tion, which contained almost exclusively compound 4
(Scheme 3). This solution was used to prepare palladium
and nickel complexes without further purification. Ligand
4 is an air- and moisture-sensitive compound and cannot
be isolated in its pure form.
The same procedure was followed for the preparation of
the ligand 3. In this case, the chlorobis(1-pyrrolyl)phos-
phane had to be synthesized, according to a published
procedure [17] (Scheme 2). The 8-(di(1H-pyrrol-1-yl) phos-
phino)quinoline (3) is a crystalline, air-stable compound,
which was purified by flash chromatography; its structure
was analysed by X-ray (Fig. 1). Table 1 gives a selection
of characteristic bond lengths and bond angles of this
structure.
2.2. Synthesis of palladium complexes modified with the
ligands 1–4 and their activity toward copolymerization of
styrene and ethylene with CO
The (P,N)-ligands 1–4 were used to prepare the mono-
cationic palladium complexes [Pd(P,N)(CH3)(NCCH3)](PF6)
(9–12) according to a two-step procedure [19] involving the
synthesis of the neutral complexes 5–8 as intermediates
(Scheme 4).
The first step in the synthesis of 8-(dipyrrolidin-1-
ylphosphino) quinoline (4) was the preparation of the
bis(N,N-pyrrolidino)chlorophosphine [18]. The next steps
The complex 6, prepared with the ligand 2, was obtained
as crystals and was analysed by X-ray (Fig. 2). Table 2
gives a selection of characteristic bond lengths and bond
N
Br
1. n-BuLi, THF, -90 oC
2. PCl(NEt2)2
N
OH
OH
P
N
O
O
P
OH
HO
O
O
N
toluene, reflux
76 %
toluene, reflux
57 %
P(NEt2)2
2
1
Scheme 1. Synthesis of phosphonito,N-ligands 1 and 2.

D. Sirbu et al. / Journal of Organometallic Chemistry 691 (2006) 1143–1150
1145
angles of this structure. As expected based on electronic
grounds, chloride is trans to the better donor, phosphorus,
while methyl is trans to the poorer donor, nitrogen.
The monocationic palladium complexes 9–12 were tested
as catalyst precursors for the copolymerization of styrene
with CO, under various reaction conditions but they were
inactive, despite the fact that with 9 and 10 there is no for-
mation of metallic palladium, at least until 200 bar carbon
monoxide. Compounds 11 and 12 were more sensitive.
The copolymerizations of ethylene with CO proved suc-
cessful only for complex 10, at 35 bar ethylene, 35 bar CO
and 80 ꢁC. The complexes were used also for the oligomer-
ization of ethylene using triisobutylaluminium (iBu3Al) at
8–60 bar and up to 80 ꢁC; they were inactive.
1. n-BuLi, THF, -90 oC
N
N
P
2.
N
N
N
Br
Cl
P
N
3, 56 %
Analysed by X-rays
NEt3
Cl
THF, 0 oC
+
2
P
N
Cl
Cl
H
Scheme 2. Synthesis of 8-(di(1H-pyrrol-1-yl)phosphino)quinoline (3).
2.3. Synthesis of the nickel complexes modified with the
ligands 1–4 and their activity toward oligomerization of
ethylene
The complexes 13 and 14, prepared with the ligands 1
and 2, proved to be paramagnetic. Therefore, their charac-
terization by NMR was impossible. The coordination of
the nitrogen heterocycle to the metal center can be verified
by infrared spectroscopy with the characteristic shift of the
m
C@C, mb(C–H) and mcycle
.
The complexes 15 and 16, prepared with the ligands 3
and 4, are diamagnetic and a full set of their NMR data
were collected. The preparation of these two complexes
was followed by in situ 31P NMR. Both reactions were very
fast and the characteristic signals of the products, appeared
almost immediately (92.1 ppm for complex 15 and
95.8 ppm for complex 16).
Fig. 1. ORTEP drawing of the compound 3.
Table 1
Relevant bond lengths (A) and angles (ꢁ) of ligand 3
˚
Very high yields of the nickel-complexes [Ni(P,N)(1-
naphthyl)Cl] (13–16) were produced following a published
procedure [20] using trans-chloro(1-naphthyl)bis (triphe-
nylphosphine) nickel (II) (Scheme 5).
P(1)–N(2)
P(1)–N(3)
P(1)–C(1)
1.720(3)
1.745(3)
1.825(3)
N(2)–C(13)
N(2)–C(10)
N(3)–C(17)
N(3)–C(14)
1.378(4)
1.383(4)
1.370(4)
1.380(4)
The nickel complexes 13–16 were tested for the oligo-
merization of ethylene using methylaluminoxane (MAO)
as cocatalyst.
N(2)–P(1)–N(3)
N(2)–P(1)–C(1)
N(3)–P(1)–C(1)
C(13)–N(2)–C(10)
C(13)–N(2)–P(1)
99.55(13)
99.72(13)
100.23(14)
108.2(3)
C(10)–N(2)–P(1)
C(17)–N(3)–C(14)
C(17)–N(3)–P(1)
C(14)–N(3)–P(1)
128.9(2)
107.4(3)
122.3(2)
130.3(2)
All catalysts were highly active at ambient temperature,
reaching values of 1.3 · 105 g C2H4/mol Ni Æ h. The cata-
lytic activity increased with increasing of the ethylene pres-
sure in all cases. The oligomerizations required low
ethylene pressure (1–12 bar) as it is shown in Table 3.
The reaction temperature rose in all the experiments and
at higher pressures, namely 10 bar for catalysts 13 and 14
and 20 bar for the other two complexes, the reactions were
too fast to be controlled. This is why the data for the olig-
omerization reactions using the complexes 13 and 14 at 8
and 12 bar could not be collected. The optimum pressure
for the catalysts 13 and 14 was 4 bar, while for the com-
plexes 15 and 16 it was 12 bar.
122.7(2)
1. n-BuLi, THF, -90 oC
N
N
2.
N
P
Br
Cl
P
N
N
N
4
ClSiMe3
0 oC, 3h
When complexes 13 and 14 were used, the main oligo-
meric products were butenes and hexenes (C4, C6). In the
case of complex 13, hexenes usually formed, while with com-
plex 14 the butenes are predominant. The amount of hex-
enes obtained increased with increasing ethylene pressure.
PCl3
Ether, 0 oC
N
N
SiMe3
2
P
Cl
N
N
H
Scheme 3. Synthesis of 8-(dipyrrolidin-1-ylphosphino)quinoline (4).

1146
D. Sirbu et al. / Journal of Organometallic Chemistry 691 (2006) 1143–1150
(PF6)
N
N
P
N
P
Cl
NCCH3
CH3
AgPF6
Cl
CH2Cl2
RT, o.n.
Pd
+
Pd
Pd
CH2Cl2/NCCH3
CH3
CH3
P
5-8, 69-95 %
1-4
9-12, 89-97 %
Scheme 4. Synthesis of the palladium complexes [Pd(P,N)(CH3)Cl] (5–8) and [Pd(P,N)(CH3)(NCCH3)](PF6) (9–12).
Table 3
Results of the oligomerization of ethylene using nickel catalysts 13–16
Nickel
catalyst
PEt
(bar)
Activity
(g C2H4/mol Ni Æ h)
Yield of oligomers (%)
C4
C6
C8
C10
C12
13
14
15
16
1
2
4
0.28 · 105
0.8 · 105
1.29 · 105
0.17 · 105
0.3 · 105
1.3 · 105
0.14 · 105
0.48 · 105
0.96 · 105
0.04 · 105
0.50 · 105
1.11 · 105
49
42
36
51
58
64
–
–
–
–
–
–
–
–
–
1
2
4
82
76
66
18
24
34
–
–
–
–
–
–
–
–
–
2
8
12
44
43
43
43
45
46
10
11
10
3
1
1
<1
<1
<1
Fig. 2. ORTEP drawing of the complex (P,N)Pd(CH3)Cl (6).
Table 2
Relevant bond lengths (A) and angles (ꢁ) for complex 6
4
8
12
57
42
35
31
42
45
8
11
13
3
4
5
1
1
2
˚
Pd–C(1)
Pd–P
2.019(5)
2.1389(10)
2.159(3)
P–O(2)
P–O(1)
P–C(14)
O(1)–C(2)
O(2)–C(13)
1.602(3)
1.611(3)
1.801(4)
1.399(4)
1.403(5)
Oligomerization conditions: 15 lmol catalyst, 30 ml toluene, 5 ml sol.
MAO (10% MAO solution in toluene) and ambient temperature.
Pd–N
Pd–Cl(1)
2.3596(11)
C(1)–Pd–P
C(1)–Pd–N
P–Pd–N
C(1)–Pd–Cl(1)
P–Pd–Cl(1)
N–Pd–Cl(1)
O(2)–P–O(1)
O(2)–P–C(14)
90.98(17)
174.8(2)
O(1)–P–C(14)
O(2)–P–Pd
O(1)–P–Pd
C(14)–P–Pd
C(2)–O(1)–P
C(13)–O(2)–P
C(21)–N–C(22)
C(21)–N–Pd
C(22)–N–Pd
99.38(16)
114.13(11)
125.33(11)
104.63(15)
122.4(2)
122.0(2)
118.1(4)
124.6(3)
117.2(2)
3. Conclusions
83.98(10)
90.81(17)
177.95(4)
94.21(10)
102.20(14)
109.77(18)
The ligands 1–4 were synthesized in good yields and
were characterized by NMR or X-ray analysis. They were
used to prepare palladium complexes 9–12, also in good
yields, these compounds being fully characterized by
NMR. The activity of the palladium complexes was inves-
tigated toward the copolymerization of styrene and ethyl-
ene with CO. They showed no activity in the case of
styrene and only complex 10 proved useful for the copoly-
merization of ethylene with CO. Therefore, we concluded
that even though the modifications introduced in the struc-
ture of (P,N)-ligands were significant, in terms of steric and
electronic properties, they had little influence on the
catalytic activity of the palladium complexes toward
polymerizations.
N
Cl
Ni
Cl
Ph3P Ni PPh3
P
N
CH2Cl2 or Toluene
RT, 1 h
+
P
1-4
13-16, 90-95 %
The nickel complexes, modified with the ligands 1–4
were synthesized and characterized by IR, MS or NMR.
They were highly active toward the oligomerization of eth-
ylene at ambient temperature and in the presence of MAO
as the cocatalyst.
Scheme 5. Synthesis of [Ni(P,N)(1-naphtyl)Cl] (13–16) complexes.
When the catalysts 15 and 16 were tested, the oligomeric
products contained 10–15% C8–C12 fractions. With com-
plex 15, the activity increased with increasing ethylene pres-
sure, but the oligomeric composition was hardly influenced.
In the case of complex 16, the amount of the higher frac-
tions increased with increasing ethylene pressure.
4. Experimental
4.1. General data
At the same pressure, complexes 13 and 14 showed
much higher activity in comparison with the complexes
15 and 16. This is probably due to the greater steric bulk-
iness around the nickel atom.
All the reactions were carried out in nitrogen atmosphere
by means of Schlenk techniques. CP grade chemicals were
used as received. Solvents were dried by standard methods

D. Sirbu et al. / Journal of Organometallic Chemistry 691 (2006) 1143–1150
1147
and freshly distilled under nitrogen. Carbon monoxide (CP
grade, 99.5%) was supplied by AGA. One and two-dimen-
sional NMR spectra were measured on Bruker instruments
(AC 200, AVANCE 400 and AMX 500) at ambient temper-
ature. The MS spectra were measured by MALDI-FT-ICR
in the positive mode on an IonSpec Ultima instrument. Our
microanalytical laboratory performed elemental analyses.
The IR spectra were recorded on a Bio-Rad Excalibur Ser-
ies FT-IR Spectrometer.
(40 ml) of 8-bromo-quinoline (1 g, 4.8 mmol) at ꢀ90 ꢁC.
The reaction temperature was increased to ꢀ78 ꢁC where
it remained for 5 min, when an equimolecular amount of
chloro-bis(1-pyrrolyl) phosphane [2] (955 mg, 4.8 mmol)
was added (the solution became colorless). The reaction
mixture was allowed to warm up to room temperature
and stirred for 4–5 h (pale yellow solution). The volatiles
were removed in vacuo and the product purified by flash
chromatography using 3% triethylamine in a mixture of
hexane:ethylacetate, 4:1. A crystalline pale green product
(700 mg) was obtained (50%). Single crystals of complex
4.2. 8-(3,5-Dioxa-4-phospha-cyclohepta[2,1-a; 3,4-a0]-
dinaphthalen-4yl)-quinoline (1)
1
3 were investigated by X-ray analysis. H NMR (CDCl3)
3
4
3
d 8.80 (dd, J 5.8, J 1.6, 1H, CH@N); 8.15 (dd, J 9.7,
3
4
In a Schlenk flask, a precooled solution of n-BuLi
(3.0 ml, 1.6 M in hexane) was added to a THF solution
(40 ml) of 8-bromo-quinoline (1 g, 4.8 mmol) at ꢀ90 ꢁC.
The reaction temperature was increased to ꢀ78 ꢁC, where
it remained for 5 min (the color of the solution turned from
light yellow to dark orange). Then, an equimolecular
amount of PCl(NEt2)2 (1 g, 4.8 mmol) was added. The reac-
tion mixture was allowed to warm up to room temperature
and was stirred for 4–5 h (the solution turned yellow). The
volatiles were removed in vacuo, toluene was added and the
solution was filtered through a pad of Celite. 8-(Bis-dieth-
ylaminophosphine)-quinoline was obtained and its presence
was confirmed by 31P NMR of the crude product, the spec-
tra showing a single resonance at d 96.5 ppm. An equimolar
amount of (R)-binaphtol (1.373 g, 4.8 mmol) was then
added and the reaction mixture was heated under reflux in
toluene for 24 h. After cooling to room temperature, the
solvent was removed and the residue was washed twice with
pentane and diethyl ether; the product was dried under high
vacuum. A pale yellow solid (1.6 g) was obtained (76%). 1H
NMR (CD2Cl2) d 9.09 (dd, 3J 4.1, 4J 1.9, 1H, CH@N); 8.21
(d, J 8.3, 1H); 8.04 (d, J 8.7, 1H); 7.95 (d, J 8.2, 1H); 7.84 (d,
J 8.0, 1H); 7.73 (d, J 8.0, 1H); 7.64 (t, 2H); 7.50 (q, 1H);
7.51–7.26 (m, 9H), 6.29 (d, J 8.7, 1H). 31P NMR: d 183.1.
Calc. for C29H18NO2P (443.43): C, 78.55; H, 4.09; N,
3.16. Found: C, 78.67; H, 4.12; N, 3.23%.
4J 1.5, 1H); 7.91 (d, J 8.1, 1H); 7.51 (dt, J 15.2, J 1.1,
1H); 7.40 (q, J 4.2, 1H); 7.04–7.01 (m, 1 H); 6.85–6.78
(m, 4H, CH@); 6.31–6.30 (m, 4H, CH@). 13C NMR d
150.1, 148.5 (d), 136.08, 135.7 (d), 132.3 (d), 130.7,
127.6, 126.6, 121.8 (Ar); 124.4, 124.3 (NCH@); 111.77,
111.74 (CH@). 31P NMR: d 68.2. Calc. for C17H14N3P:
C, 70.10; H, 4.84; N, 14.43. Found: C 69.93; H, 4.93;
N, 14.07%. HRMS: Found, 291.0918; calc. for C17H14-
N3P, 291.0929.
4.5. 8-(Dipyrrolidin-1-ylphosphino)-quinoline (4)
In a Schlenk flask, a precooled solution of n-BuLi
(3.0 ml, 1.6 M in hexane) was added to a THF solution
(40 ml) of 8-bromo-quinoline (1 g, 4.8 mmol) cooled at
ꢀ90 ꢁC. The reaction temperature was increased to
ꢀ78 ꢁC and remained at this temperature for 5 min, when
an equimolecular amount of bis(N,N-pyrrolidino) chloro-
phosphine [3] (955 mg, 4.8 mmol) was added. The reaction
mixture was stirred for 3 h, while it warmed up to ambient
temperature. The process was followed by in situ 31P
NMR. After 3 h, the signal of the initial phosphine at
163 ppm was replaced by the single resonance of the prod-
uct observed at 77.5 ppm. The volatiles were removed in
vacuo, toluene was added and the resulting mixture was fil-
tered under nitrogen. A clear yellow toluene solution was
obtained, which contained almost exclusively the com-
pound 4. This solution was used to prepare palladium
and nickel complexes without further purification.
4.3. 8-(1,3-Dioxa-2-phospha-dibenzo[a,c]cyclohepten-2-
yl)-quinoline (2)
Following the procedure used to prepare compound 1
but using the 2,20-dihydroxydiphenyl (893 mg, 4.8 mmol)
in the second step, the title compound was obtained as a
4.6. General procedure for the preparation of the chloro-
(methyl)palladium complexes 5–8
1
white powder (940 mg, 57% yield). H NMR (CD2Cl2) d
The ligands (0.8 mmol) were dissolved in 3 ml dichloro-
methane andaddedby a syringeto asolution of(g2,g2-cyclo-
octa-1,5-dien)chloro(methyl)palladium ((COD)Pd(Me)Cl)
[21] (212 mg, 0.80 mmol) and 3 ml dichloromethane. The
mixture was stirred for 1–3 d under argon at ambient temper-
ature. The solution was then filtered through Celite and the
solvent evaporated; yellow oil was obtained. This was
washed with hexane (3·), redissolved in dichloromethane
and cooled; the products were precipitated by the addition
of hexane. Each complex was isolated by filtration and then
dried under high vacuum.
3
4
3
4
9.09 (dd, J 5.5, J 1.5, 1H, CH@N); 8.29 (dd, J 9.7, J
1.5, 1H); 7.94 (d, J 8.0, 1H); 7.82 (d, J 7.0, 1H); 7.56 (q,
1H); 7.49–7.43 (m, 3H); 7.26 (t, J 7.3, 2H); 7.18 (t, J 7.5,
2H); 6.74 (d, J 7.9, 2H). 31P NMR: d 185.9. HRMS:
Found, 344.0834; calc. for C21H14NO2P, 344.0823.
4.4. 8-(Di(1H-pyrrol-1-yl)phosphino)-quinoline (3)
In a Schlenk flask, a precooled solution of n-BuLi
(3.0 ml, 1.6 M in hexane) was added to a THF solution

1148
D. Sirbu et al. / Journal of Organometallic Chemistry 691 (2006) 1143–1150
4.6.1. {8-(3,5-Dioxa-4-phospha-cyclohepta[2,1-a; 3,4-a0]
dinaphthalen-4yl)-quinoline}chloro(methyl)palladium (5)
360 mg (75%) white solid were obtained. 1H NMR
(CDCl3) d 10.03 (d, J 3.5, 1H, CH@N); 8.41 (d, J 8.35,
1H); 8.11 (d, J 8.05, 1H); 8.06 (d, J 8.85, 1H); 8.01–7.95
(m, 3H); 7.70–7.68 (m, 1H); 7.65 (d, J 8.85, 1H); 7.55–
7.51 (m, 2H); 7.45–7.42 (m, 2H); 7.38–7.32 (m, 3H); 7.18
(t, J 8.05, 1H); 7.12 (d, J 8.85, 1H); 0.69 (s, 3H, Pd–
CH3). 31P NMR: d 163.7. HRMS: Found, 564.8768
(M+ꢀCl); calc. for C30H21NO2PPd, 564.8773.
chloride. The pale yellow filtrate was evaporated under
vacuum and yellow oil was obtained; upon treatment with
hexane (3 · 3 ml) and drying under vacuum, the complexes
9–12 were obtained as powders (89–97% yield).
4.7.1. (Acetonitril-jN){8-(3,5-dioxa-4-phospha-cyclo-
hepta[2,1-a; 3,4-a0]dinaphthalen-4yl)-quinoline}methyl
palladium(+) hexafluoro phosphate (9)
A beige powder (316 mg) was obtained (96%). 1H NMR
(CD2Cl2) d 9.24 (s, 1H, CH@N); 8.61 (d, J 7.73, 1H); 8.26
(d, J 8.02, 1H); 8.15 (d, J 8.80, 1H); 8.09–8.05 (m, 3H); 7.66
(d, J 8.82, 1H); 7.61–7.57 (m, 2H); 7.52 (t, J 7.1, 1H); 7.42–
7.37 (m, 5H); 7.22 (t, J 10.0, 1H); 7.16 (d, J 8.82, 1H); 2.22
(s, 3H, NCCH3); 0.46 (s, 3H, PdCH3). 31P NMR: d 164.3,
ꢀ143.1 (PF6). 19F NMR: d ꢀ73 (d). HRMS: Found,
564.8765 (M+ꢀNCCH3ꢀPF6); calc. for C30H21NO2PPd,
564.8773.
4.6.2. {8-(1,3-Dioxa-2-phospha-benzo[a,c]cyclohepten-2-
yl)-quinoline}chloro(methyl)palladium (6)
Yellow crystals (276 mg, 69%) were obtained and were
1
analyzed by X-ray. H NMR (CDCl3) d 10.01 (d, J 4.05,
1H, CH@N); 8.42 (d, J 8.25, 1H); 8.15 (d, J 6.05, 1H);
7.67 (q, J 8.25, J 4.85, 1H); 7.60 (t, J 4.15, 2H, Ph); 7.54
(t, J 3.55, 2H, Ph); 7.44–7.40 (m, 4H, Ph); 7.15 (d, J 7.60,
2H); 0.82 (s, 3H, Pd–CH3). 31P NMR: d 162.2. HRMS:
Found, 464.0033 (M+ꢀCl); calc. for C22H17NO2PPd,
464.0026.
4.7.2. (Acetonitril-jN){8-(1,3-dioxa-2-phospha-dibenzo-
[a,c]cyclohepten-2-yl)-quinoline}methylpalladium(+)
hexafluoro phosphate (10)
A beige powder (277 mg) was obtained (97%). 1H NMR
(CD2Cl2) d 9.24 (s, 1H, CH@N); 8.62 (d, J 7.97, 1H); 8.31
(d, J 7.97, 1H); 7.92 (s, 1H); 7.74–7.64 (m, 3H, Ph); 7.57–
7.45 (m, 5H, Ph); 7.19 (d, J 7.08, 2H); 2.47 (s, 3H,
NCCH3); 0.63 (s, 3H, PdCH3). 31P NMR: d 162.9,
ꢀ143.1 (PF6). HRMS: Found, 464.0033 (M+ꢀNCCH3ꢀ
PF6); calc. for C22H17NO2PPd, 464.0026.
4.6.3. {8-(Di(1H-pyrrol-1-l)phosphino)-quinoline}chloro-
(methyl)palladium (7)
1
A yellow solid (280 mg, 78%) was obtained. H NMR
3
4
(CDCl3) d 9.95 (dd, J 4.83, J 1.56, 1H, CH@N); 8.44
3
4
3
(dt, J 8.34, J 1.83, 1H); 8.19 (d, J 8.08, 1H); 8.13 (q, J
4
3
4
9.74, J 7.20, 1H); 7.77 (t, J 8.27, 1H); 7.68 (q, J 6.57, J
4.84, 1H); 6.98 (s, 4H, CH@); 6.40 (s, 4H, CH@); 1.13
(d, J 2.17, 3H, Pd–CH3). 31P NMR: d 94.6. HRMS: Found,
412.7269 (M+ꢀCl); calc. for C18H17N3PPd, 412.7279.
4.7.3. (Acetonitril-jN){8-(di(1H-pyrrol-1-yl)phosphino)-
quinoline}methylpalladium(+) hexafluoro phosphate (11)
A light brown powder (242 mg) was obtained (92%). 1H
4.6.4. {8-(Dipyrrolidin-1-ylphosphino)quinoline}chloro-
(methyl)palladium (8)
3
4
NMR (CD2Cl2) d 9.25 (dd, J 4.74, J 1.45, 1H, CH@N);
1
A yellow solid 346 mg was obtained (95%). H NMR
3
8.62 (d, J 8.38, 1H); 8.33 (d, J 8.10, 1H); 8.23 (q, J 9.44,
3
4
(CDCl3) d 9.93 (s, 1H, CH@N); 8.34 (dt, J 8.29, J 1.72,
3
4
3
4J 6.71, 1H); 7.96 (q, J 6.62, J 4.80, 1H); 7.87 (dt, J
8.35, 4J 1.34, 1H); 7.01 (m, 4H, CH@); 6.52 (m, 4H,
CH@); 2.43 (s, 3H, NCCH3); 0.94 (s, 3H, Pd–CH3). 31P
NMR: d 97.76, ꢀ143.1 (PF6). HRMS: Found, 598.7443;
calc. for C20H20F6N4P2Pd, 598.7448.
3
1H); 8.04–8.00 (m, 2H); 7.69 (t, J 8.01, 1H); 7.57 (q, J
4
6.55, J 4.84, 1H); 3.25–3.17 (m, 8H, CH2); 1.89–1.79 (m,
8H, CH2); 0.85 (s, 3H, PdCH3). 31P NMR: d 95.5. 13C
NMR d 153.0, 149.1 (d), 138.0, 136.9 (d), 132.8, 131.3,
129.3 (d), 128.2, 127.0 (d), 122.6 (Ar); 48.2 (d, CH2);
26.1(d, CH2); 0.002 (PdCH3). HRMS: Found, 420.7912
(M+ꢀCl); calc. for C18H25N3PPd, 420.7919.
4.7.4. (Acetonitril-jN){8-(dipyrrolidin-1-ylphosphino)-
quinoline}methylpalladium (+) hexafluoro phosphate (12)
1
A pale yellow powder (237 mg) was obtained (89%). H
4.7. General procedure for the preparation of the methyl-
(acetonitrile)palladium complexes 9–12
NMR (CD2Cl2) d 9.25 (s, 1H, CH@N); 8.45 (dt, 3J 8.36, 4J
3
4
1.60, 1H); 8.10 (d, J 8.0, 1H); 8.05 (q, J 13.1, J 9.0, 1H);
7.88–7.85 (m, 1H); 7.76 (t, J 8.15, 1H); 3.23–3.14 (m, 8H,
CH2); 2.5 (s, 3H, CNCH3), 1.91–1.81 (m, 8H, CH2); 0.57
(s, 3H, Pd–CH3). 31P NMR: d 94.67, ꢀ143.1 (PF6). 13C
NMR d 153.5, 148.3 (d), 139.0, 135.8 (d), 133.3, 132.2
(d), 129.5 (d), 127.5 (d), 123.9 (Ar), 120.5 (CNCH3), 48.3
(d, CH2), 26.1 (d, CH2), 2.64 (CNCH3), ꢀ1.4 (PdCH3).
HRMS: Found, 420.7915 (M+ꢀNCCH3ꢀPF6); calc. for
C18H25N3PPd, 420.7919. Calc. for C20H28N4F6P2Pd
(606.83): C, 39.59; H, 4.65; N, 9.23. Found: C, 40.00; H,
4.99; N, 8.90%.
In a two-neck, 50-ml flask covered with aluminum foil,
chloro(methyl)palladium complexes 5–8 (0.44 mmol) were
dissolved in 5 ml of a mixture of dichloromethane/acetoni-
trile (5:1, v/v) under argon and cooled to 0 ꢁC. The AgPF6
(0.44 mmol), dissolved in a 3-ml solution of dichlorometh-
ane/acetonitrile (5:1, v/v), was added to the mixture
through a dropping funnel. The reaction mixture was stir-
red for 1 h at 0 ꢁC and was warmed to ambient tempera-
ture, at which it was maintained for another hour.
Filtration through Celite removed the precipitated silver

D. Sirbu et al. / Journal of Organometallic Chemistry 691 (2006) 1143–1150
1149
Table 4
4.8. General procedure for the preparation of the nickel
complexes 13–16
Crystal data and structure refinement of ligand 3
Empirical formula
Formula weight
T (K)
k (A)
Crystal system
Space group
C17H14N3P
291.28
298(2)
0.71073
Triclinic
Asolutionofeachoftheligands1–4(0.5 mmol)inCH2Cl2
(3 ml) was added to a solution of trans-chloro(1-naph-
thyl)bis(triphenylphosphyne)nickel (II) (372 mg, 0.5 mmol)
in CH2Cl2 (10 ml) and the reaction mixture was stirred for
1 h. The resultant solution was concentrated to about 5 ml
and hexane (5 ml) was added to completely precipitate the
nickel complexes 13–16, which were isolated by filtration
and dried under high vacuum.
˚
ꢀ
P1
Unit cell dimensions
˚
a (A)
9.1647(16)
11.852(2)
15.069(3)
73
78.866(3)
75
1501.3(5)
4
1.289
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
4.8.1. Chloro(1-naphthyl){8-(3,5-dioxa-4-phosphacyclo-
hepta[2,1-a; 3,4-a0]dinaphthalen-4yl)-quinoline}nickel (II)
(13)
A beige powder (312 mg) was obtained (94%). Paramag-
netic compound. HRMS: Found, 628.0973 (M+ꢀCl); calc.
for C39H25NO2PNi, 628.09709. IR (KBr) cmꢀ1: 1622m
(mC@C); 1157m (mb(C–H)); 1030, 1000s (mcycle).
3
˚
V (A )
Z
Dcalc (g cmꢀ3
)
Absorption coefficient (mmꢀ1
Crystal size (mm)
)
0.179
0.57 · 0.37 · 0.25
13193, 6091
0.0372
Full-matrix least-squares
on F2
Reflections collected, unique
Rint
Refinement method
4.8.2. Chloro(1-naphthyl){8-(1,3-dioxa-2-phosphadibenzo-
[a,c]cyclohepten-2-yl)quinoline}nickel (II) (14)
A beige powder (268 mg) was obtained (95%). Paramag-
netic compound. HRMS: Found, 470.1307 (M+ꢀNiꢀCl);
calc. for C31H21NO2P, 470.13044. IR (KBr) cmꢀ1: 1601m
(mC@C); 1158m (mb(C–H)); 1051, 1000m (mcycle).
Data, restraints, parameters
Goodness-of-fit
R, Rw
6091, 0, 379
1.101
0.0835, 0.1907
0.728/ꢀ0.257
ꢀ3
˚
Minimum/maximum residual density (e A
)
Table 5
Crystal data and structure refinement of complex [Pd(P,N)(CH3)Cl] (10)
4.8.3. Chloro(1-naphthyl){8-(di(1H-pyrrol-1-yl)-
phosphino)quinoline}nickel (II) (15)
Empirical formula
Formula weight
T (K)
C22H17ClNO2PPd
499.5
293(2)
A yellow powder (238 mg) was obtained (93%). 1H
NMR (500 MHz, CDCl3): d 10.1 (s, 1H, CH@N); 9.02
(d, 1H, NiCCH); 8.52 (d, 1H); 8.22 (d, 1H); 8.07 (s, 1H);
7.76 (s, 2H), 7.53 (d, 1H); 7.35 (m, 3H); 7.25 (s, 2H); 7.12
(s, 1H); 7.00 (s, 1H); 6.41 (s, 2H); 6.14 (s, 2H); 5.79 (s,
˚
k (A)
0.71073
Orthorombic
P/bca
Crystal system
Space group
Unit cell dimensions
2H). 31P NMR:
d 92.1. HRMS: Found, 477.1673
˚
a (A)
11.5030(8)
14.1591(9)
29.903(2)
(M+ꢀCl); calc. for C27H21N3NiP, 477.1689. IR (KBr)
cmꢀ1: 1606m (mC@C); 1151w (mb(C–H)); 1039, 1017s (mcycle).
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
90
90
90
4870.3(6)
6
1.690
0.288
0.39 · 0.22 · 0.17
30317, 4975
0.0315
4.8.4. Chloro(1-naphthyl){8-(dipyrrolidin-1-
ylphosphino)quinoline}nickel (II) (16)
3
˚
V (A )
1
Z
A red powder (234 mg) was obtained (90%). H NMR
Dcalc (g cmꢀ3
)
(500 MHz, CDCl3): d 10.08 (s, 1H, CH@N); 9.70 (s, 1H,
NiCCH); 8.30 (s, 1H); 7.98 (s, 1H); 7.72–7.24 (m, 8H);
7.05 (s, 1H); 3.67 (s, 2H, CH2); 3.38–3.14 (m, 4H, CH2);
2.64 (s, 2H, CH2); 1.98–1.57 (m, 8H, CH2). 31P NMR: d
95.8. HRMS: Found, 485.2373 (M+ꢀCl); calc. for
C27H29N3NiP, 485.2329. IR (KBr) cmꢀ1: 1604w (mC@C);
1152m (mb(C–H)); 954, 915m (mcycle).
Absorption coefficient (mmꢀ1
Crystal size (mm)
)
Reflections collected, unique
Rint
Refinement method
Full-matrix least-squares
on F2
Data, restraints, parameters
Goodness-of-fit
R, Rw
4975, 0, 298
1.116
0.0465, 0.1076
0.726/ꢀ0.384
ꢀ3
˚
4.9. General procedure for ethylene oligomerization
Minimum/maximum residual density (e A
)
A Medimex autoclave (100 ml) was loaded with 15 lmol
of each of the nickel complexes 13–16 and 30 ml toluene.
The autoclave was connected to an ethylene source through
a Buchi-bpc gas-flow controller, which maintained a con-
stant ethylene pressure. It also enabled the monitoring of
the ethylene consumption. The mixture was stirred for
10 min; 5 ml of MAO (10% solution in toluene) were then
added by a syringe. The autoclave was kept at the same
pressure for a limited period of time; the catalytic reaction
was terminated by adding acidified water. An aliquot of the
organic layer was analyzed by GC and GC–MS.

1150
D. Sirbu et al. / Journal of Organometallic Chemistry 691 (2006) 1143–1150
4.10. Structure determination
00196 and Swiss Research Council (BBW) is gratefully
acknowledged.
X-ray structural measurements of the ligand 3 and the
complex [Pd(P,N)(CH3)Cl] (10) were carried out on a Bru-
ker CCD diffractometer (SMART PLATFORM, with
CCD detector, graphite monochromator, Mo Ka radia-
tion). The program SMART was used for data collection.
Integration was performed with SAINT. The structure solu-
tion (Patterson method) and refinement on F2 were accom-
plished with SHELXTL-97. Model plots were made with
ORTEP32. All non-hydrogen atoms were refined freely
with anisotropic displacement parameters. The hydrogen
atoms were refined at calculated positions riding on their
carrier atoms. Weights were optimized in the final refine-
ment cycles. Tables 4 and 5 give the crystallographic data
for the compounds 3 and 10.
References
[1] G.R. Newkome, Chem. Rev. 93 (1993) 2067.
[2] Z.Z. Zhang, H. Cheng, Coord. Chem. Rev. 1 (1996) 147.
[3] P. Espinet, K. Soulantica, Coord. Chem. Rev. 499 (1999) 193.
[4] M. Gomez, G. Muller, M. Rocamora, Coord. Chem. Rev. 769 (1999)
193.
[5] C.S. Slone, D.A. Weinberger, C.A. Mirkin, Prog. Inorg. Chem. 48
(1999) 233.
[6] G. Helmchen, A. Pfaltz, Acc. Chem. Res. 33 (2000) 336.
[7] P. Braunstein, F. Naud, Angew. Chem. Int. Ed. 40 (2001) 680.
[8] F. Speiser, P. Braunstein, L. Saussine, R. Welter, Organometallics 23
(2004) 2613.
[9] F. Speiser, P. Braunstein, L. Saussine, Organometallics 23 (2004) 2633.
[10] G. Delapierre, M. Achard, G. Buono, Tetrahedron Lett. 43 (2002)
4025–4028.
[11] G. Francio, D. Drommi, C. Graiff, F. Faraone, A. Tiripicchio,
Inorg. Chim. Acta 338 (2002) 59–68.
5. Supplementary material
[12] W.H. Sun, Z. Li, H. Hu, B. Wu, H. Yang, N. Zhu, X. Leng, H.
Wang, New J. Chem. 26 (2002) 1474–1478.
[13] O. Daugulis, M. Brookhart, Organometallics 21 (2002) 5926.
[14] H.P. Chen, Y.H. Liu, S.M. Peng, S.T. Liu, Organometallics 22
(2003) 4893.
[15] W.H. Sun, W. Zang, T. Gao, X. Tang, L. Chen, Y. Li, X. Jin, J.
Organomet. Chem. 689 (2004) 917.
[16] M.E. Bluhm, c. Folli, O. Walter, M. Doring, J. Mol. Catal. 229
(2005) 177.
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic Data
Centre, CCDC Nos. 270149 and 270150. These data can be
obtained free of charge via www.ccdc.cam.ac.uk/data_re-
quest/cif, by e-mailing to data_request@ccdc.cam.ac.uk,
or by contacting The Cambridge Crystallographic Data
Centre, 12, Union Road, Cambridge CB2 1EZ, UK; fax:
+44 1223 336033.
[17] R. Jackstell, H. Klein, M. Beller, K.-D. Wiese, D. Rottger, Eur. J.
Chem. (2001) 3871–3877.
[18] W.K.D. Brill, J. Nielsen, M.H. Caruthers, J. Am. Chem. Soc. 113
(1991) 3972–3980.
[19] R.E. Rulke, J.M. Ernsting, A.L. Spek, C.J. Elsevier, P.W.N.M. van
Leeuwen, K. Vrieze, Inorg. Chem. 32 (1993) 5769.
[20] W. Sun, Z. Li, H. Hu, B. Wu, H. Yang, N. Zhu, X. Leng, H. Wang,
New J. Chem. 26 (2002) 1474–1478.
Acknowledgements
Financial support from European Network Palladium
5th Framework Program, Contract No. HPRN-CT-2002-
[21] M. Sperrle, G. Consiglio, J. Am. Chem. Soc. 117 (1995) 12130.