Synthesis, characterization and catalytic behaviors of neutral nickel complexes: Arylnickel N-alkyl-6-(1-(arylimino)ethyl)picolinamide

Article abstract of DOI:10.1016/j.jorganchem.2008.01.004

A series of novel neutral nickel complexes, aryl (phenyl or naphthyl) nickel N-alkyl-6-(1-(arylimino)ethyl)picolinamides, were synthesized and characterized by NMR and IR spectroscopy and elemental analysis. Single-crystal X-ray diffraction analyses of the complexes C2, C3 and C7 reveal distorted square-planar geometry along with the molecular structure of one free ligand L1. On activation with diethylaluminum chloride (Et₂AlCl), the nickel complexes exhibited moderate catalytic activities for ethylene oligomerization, and the catalytic activity was up to 2.45 × 10⁵ g mol^-1(Ni) h^-1 in the presence of 1 equiv. PPh₃. Moreover, these complexes also exhibit moderate activities for Kumada-Corriu reaction and polymerization of methyl methacrylate.

Full text of DOI:10.1016/j.jorganchem.2008.01.004

Available online at www.sciencedirect.com
Journal of Organometallic Chemistry 693 (2008) 1683–1695
www.elsevier.com/locate/jorganchem
Synthesis, characterization and catalytic behaviors of neutral
nickel complexes: Arylnickel N-alkyl-6-(1-(arylimino)ethyl)picolinamide
Miao Shen, Peng Hao, Wen-Hua Sun *
Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Sciences, Institute of Chemistry,
Chinese Academy of Sciences, Beijing 100080, China
Received 20 December 2007; received in revised form 3 January 2008; accepted 3 January 2008
Available online 15 January 2008
In memorial of the late Professor Dr. F. Albert Cotton, Texas A&M University.
Abstract
A series of novel neutral nickel complexes, aryl (phenyl or naphthyl) nickel N-alkyl-6-(1-(arylimino)ethyl)picolinamides, were synthe-
sized and characterized by NMR and IR spectroscopy and elemental analysis. Single-crystal X-ray diffraction analyses of the complexes
C2, C3 and C7 reveal distorted square-planar geometry along with the molecular structure of one free ligand L1. On activation with
diethylaluminum chloride (Et2AlCl), the nickel complexes exhibited moderate catalytic activities for ethylene oligomerization, and the
catalytic activity was up to 2.45 Â 105 g molÀ1(Ni) hÀ1 in the presence of 1 equiv. PPh3. Moreover, these complexes also exhibit moderate
activities for Kumada–Corriu reaction and polymerization of methyl methacrylate.
Ó 2008 Elsevier B.V. All rights reserved.
Keywords: N-Alkyl-6-(1-(arylimino)ethyl)picolinamide; Neutral nickel complex; Ethylene oligomerization; Kumada–Corriu reaction; Polymerization of
methyl methacrylate
1. Introduction
or neutral nickel catalysts designed by Grubbs and cowork-
ers [10]. Neutral nickel catalysts are less electrophilic than
those of the cationic family, and this property has been
used to produce copolymerization of olefins containing
polar functional groups [10].
In the past decade, late-transition metal complexes
including nickel complexes have attracted great attention
in both academic and industrial researches of catalytic
chemistry [1]. Two main kinds of nickel complexes: neutral
and cationic complexes have been recognized according to
the nature of ligands and their bonding around the nickel
atom. The cationic nickel complexes are commonly four-
coordinated nickel halides containing bidentate ligands
such as P^O [2], P^P [3], and N^N [4], and also some of
the five-coordinated nickel halides incorporating tridentate
ligands of N^N^O [5], N^P^N [6], P^N^P [7], P^N^N [7], and
N^N^N [8]. The neutral nickel complexes are nickel
coordinated with anionic ligands and alkyl or aryl groups
such as SHOP precursor of bis(P–O) nickel complexes [9]
A series of nickel halide complexes containing tridentate
N^N^N ligands have been the focus of our group [8a,8d,11].
These complexes exhibit good to high activities towards
ethylene reactivity. Inspired by the unique properties of
neutral nickel complexes, we have prepared some new
anionic organic compounds for use as ligands in the
preparation some neutral nickel complexes. Some ligands
developed by our group, for example, the 2-(ethylcarboxy-
lato)-6-imino pyridines were used in forming cationic com-
plexes of iron [12], cobalt [12], nickel [5b] and palladium
[13]. These could also be used to construct tridentate anio-
nic ligands through facile transformations of the N-alkyl-
6-(1-(arylimino)ethyl)picolinamides. Further reactions
with trans-[NiCl(Ph)(PPh3)2] or trans-[NiCl(Naph)(PPh3)2]
*
Corresponding author. Tel.: +86 10 62557955; fax: +86 10 62618239.
E-mail address: whsun@iccas.ac.cn (W.-H. Sun).
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.01.004

1684
M. Shen et al. / Journal of Organometallic Chemistry 693 (2008) 1683–1695
yielded their neutral nickel complexes. In the presence of
diethylaluminum chloride (Et2AlCl), all the nickel
complexes performed moderate activities toward ethylene
oligomerization, and such activity was up to 2.45 Â
105 g molÀ1(Ni) hÀ1 in the presence of 1 equiv. PPh3.
Under proper conditions, these complexes also exhibit
moderate activities toward the Kumada–Corriu reaction
and polymerization of methyl methacrylate. Herein, the
synthesis and characterization of these new neutral nickel
complexes are reported along with their catalytic behaviors
towards ethylene oligomerization, the Kumada–Corriu
reaction and polymerization of methyl methacrylate.
2. Results and discussion
Fig. 1. Molecular structure of L1. Thermal ellipsoids are shown at 30%
probability.
2.1. Synthesis and characterization of ligands L1–L8
The ester-substituted pyridylimine compounds used in
the following were prepared according to the previously
reported procedures [12,13b]. The direct reactions of
ethyl-6-(1-(arylimino)ethyl)picolinate with butylamine or
octylamine or phenylmethanamine gave the (E)-N-akyl-6-
(1-(arylimino)ethyl)picolinamide derivatives in good yields
(Scheme 1). Solvents such as MeOH, EtOH, pyridine and
toluene, MeOH was found to be the most efficient one.
The organic compounds L1–L8 were routinely character-
ized with elemental analysis, IR spectroscopic and NMR
analysis. L1 was further characterized by the single-crystal
X-ray diffraction analysis (Fig. 1).
Hydrogen atoms have been omitted for clarity. Selected
bond distances (A) and angles (°) are as follows: N(2)–
C(10), 1.351(3); N(3)–C(11), 1.274(3); N(3)–C(13),
1.425(4); O–C(5), 1.224(3); N(1)–C(5), 1.315(4); N(1)–C(4),
1.443(4); C(11)–N(3)–C(13), 121.2(3); C(5)–N(1)–C(4),
124.0(3); O–C(5)–N(1), 123.7(3); N(1)–C(5)–C(6), 116.5(3).
˚
2.2. Synthesis and characterization of neutral nickel
complexes C1–C10
The nickel complexes C1–C10 were prepared according
to a modified procedure (Scheme 2) [10a,14,15]. The
3 equiv. NaH was added into the THF solution of the cor-
responding ligands. Gas evolved and the solution color
changed to orange in 1 h. Then the resultant solution was
filtered, and the filtrate was dried under vacuum to yield
the sodium salt, which was combined with trans-[NiCl-
(Naph)(PPh3)2] or trans-[NiCl(Ph)(PPh3)2] in toluene. The
mixture was then stirred at room temperature for 12 h to
yield a deep brown solution. After filtration, concentration
and then precipitation by layering with pentane, the crude
product was obtained in satisfactory yields (43–61%).
Single crystals of L1 suitable for X-ray diffraction anal-
ysis were obtained by slow evaporation of solvent from
solutions in diethyl ether. The molecular structure revealed
its E conformation at the C@N bonds of pyridyl group
with aryl or alkyl groups, which minimizes steric con-
straints in the free molecule. In addition, the dihedral angle
between phenyl ring and pyridyl ring is 93.4°. The imino
˚
group with a bond length of 1.274(3) A is in typical range
of the C@N length. Selected bond lengths and angles are
listed below, see Fig. 1.
H
N
O
R1
R1
N
R3
N
Et
H2N R3
MeOH
i) NaH
N
O
N
O
ii) NiCl(R)(PPh3)2
R2
R1
R2
R1
H
N
R1
N
R3
O
R1
N
N
O
N
N
R3
Ni
R2
R1
R
R2
R1
L1 L2 L3 L4
Me Et i-Pr Me
L5
Me
H
L6 L7 L8
Me i-Pr Me
R1
R2
R3
R = Naph Ln Cn
H
H
H
H
H
H
Me
R = Ph
R = Ph
L1 C9
n-Bu n-Bu n-Bu n-C8H15 n-C8H15 Bn Bn n-Bu
L3 C10
Scheme 1. Synthesis of L1–L8.
Scheme 2. Synthesis of nickel complexes C1–C10.

M. Shen et al. / Journal of Organometallic Chemistry 693 (2008) 1683–1695
1685
Table 1
Complexes C1–C10 are all air-stable deep brown powders
˚
Selected bond lengths (A) and angles (°) for complexes C2 and C3
C2 C3
and highly soluble in toluene, diethyl ether, CH2Cl2 and
CHCl3, but insoluble in alkanes. The naphthyl-containing
complexes C1–C8 are stable in solution and in the solid
state, however, the phenyl-containing complexes C9 and
C10 slowly decompose in solution after several days. All
the complexes were carefully characterized by elemental
analysis, IR spectroscopic and NMR analysis. According
to the NMR spectra, the diamagnetic Ni(II) complexes
adopt square-planar geometry. In addition, complexes
C2, C3 and C7 were further characterized by single-crystal
X-ray diffraction analysis. These complexes show new
molecular structures of the nickel complexes.
Bond lengths
Ni(1)–N(1)
Ni(1)–N(2)
Ni(1)–N(3)
Ni(1)–C(19)
N(1)–C(4)
N(1)–C(5)
N(3)–C(11)
N(3)–C(13)
O(1)–C(5)
1.887(4)
1.891(3)
1.851(3)
1.947(3)
1.896(4)
1.506(5)
1.338(5)
1.297(4)
1.461(4)
1.247(4)
1.863(4)
1.932(3)
1.914(5)
1.458(9)
1.330(7)
1.302(5)
1.444(6)
1.255(6)
Bond angles
N(2)–Ni(1)–N(1)
N(2)–Ni(1)–C(19)
N(1)–Ni(1)–C(19)
N(2)–Ni(1)–N(3)
N(1)–Ni(1)–N(3)
C(19)–Ni(1)–N(3)
82.63(2)
176.93(2)
99.5(2)
80.58(2)
163.21(2)
97.27(2)
82.13(1)
175.83(2)
96.26(1)
80.87(1)
162.89(1)
100.83(1)
Crystals of C2 suitable for single-crystal X-ray analysis
were obtained by slow evaporation of its diethyl ether
solution. The molecular structure of C2 is shown in
Fig. 2, and selected bond lengths and angles are listed in
Table 1. In the solid state, the molecule adopts distorted
square-planar geometry around the central nickel atom.
˚
The nickel center slightly deviates by 0.021 A from the
Crystals of complex C3 were grown from a mixed solu-
tion of diethyl ether and hexane. The molecular structure
of C3 is shown in Fig. 3. In complex C3, the nickel center
coplanar plane formed by N(1), N(2), N(3) and C(19).
The N(1)–Ni(1)–N(3) angle is 163.21(2)°, and the corre-
sponding N(2)–Ni(1)–C(19) angle is even much closer to
linear at 176.93(2)°. The ‘‘intra-chelate angles” at Ni are
80.58(2)° (N(2)–Ni(1)–N(3)) and 82.63(2)° (N(2)–Ni(1)–
N(1)) respectively, whereas the remaining pair of ligand
angles at nickel are 99.5(2)° (N(1)–Ni(1)–C(19)) and
97.27(2)° (C(19)–Ni(1)–N(3)). The plane of the naphthyl
ring is rotated from the coordination plane by 77.6°. The
imino-N phenyl ring is nearly perpendicular to the coordi-
nation plane with the dihedral angle of 86.1°. The Ni–N
˚
deviates by 0.020 A from the plane formed by N(1), N(2),
N(3) and C(19), the four chelate angles are 80.87(1)°
(N(2)–Ni(1)–N(3)), 82.13(1)° (N(2)–Ni(1)–N(1)), 96.26(1)°
(N(1)–Ni(1)–C(19)) and 100.83(1)° (C(19)–Ni(1)–N(3)),
respectively. The structure is similar to that of C2. The
similarities include the shortest Ni(1)–N(2) (pyridyl)
˚
˚
(1.851(3) A) compared with Ni–N(1) (1.891(3) A) bond
˚
and Ni–N(3) (imino) (1.947(3) A) bond. The most notice-
˚
able differences are the dihedral angles (75.9°) between the
coordination plane and the naphthyl plane and (86.9°)
between phenyl ring at the imino-N and coordination plane.
The differences are probably due to the more bulky groups
at the ortho-positions of the imino-N aryl ring.
and Ni(1)–C19 bonds are around 1.9 A which are similar
to those known for nickel complexes [10]. However, the
˚
˚
Ni(1)–N(2) distance (1.862(4) A) is about 0.10 A shorter
˚
than the bond length of Ni(1)–N(3) (1.933(3) A) and only
slightly shorter than that of Ni(1)–N(1) (1.887(4) A).
˚
Fig. 2. Molecular structure of complex C2. Thermal ellipsoids are shown
Fig. 3. Molecular structure of complex C3. Thermal ellipsoids are shown
at 30% probability. Hydrogen atoms have been omitted for clarity.
at 30% probability. Hydrogen atoms have been omitted for clarity.

1686
M. Shen et al. / Journal of Organometallic Chemistry 693 (2008) 1683–1695
In the structure of complex C7, there are two indepen-
dent molecules that have slightly different bond lengths
and bond angles (Table 2). In molecule (a), the average
deviation from the plane of Ni(1), N(1), N(2), N(3),
˚
˚
C(19) is 0.1001 A while this deviation is 0.0989 A in mole-
cule (b). Furthermore, differences are observed for the dihe-
dral angles between the naphthyl plane and the
coordination plane, and between the phenyl ring attached
to the imino-N and the coordination plane (110.2° and
100.2° in (a), 108.4° and 82.0° in (b), respectively). Simi-
larly, in both of the molecules, the Ni–N distances and
the imino C@N distance are nearly identical and the Ni–
N (pyridyl) bond is shorter than that of the other two
Ni–N bonds in each molecule, which is also similar to the
case in the complexes C2 and C3. All the Ni–N bonds of
these three complexes (C2, C3, C7) are obviously shorter
than the Ni–N bond of the cationic nickel complexes bear-
ing 2-(ethylcarboxylato)-6-iminopyridyl ligand [14] (see
Fig. 4).
2.3. Ethylene oligomerization
The titled nickel complexes were initially investigated
toward ethylene reactivity with promotion by various
cocatalysts including MAO, MMAO, Et2AlCl and AlEt3.
Basically all systems are active for ethylene oligomerization
according to the data observed with C1 (entries 1–4 in
Table 3). The best cocatalyst is Et2AlCl. Therefore, further
studies of all the nickel complexes for ethylene oligomeriza-
tion were carried out with Et2AlCl as cocatalyst, and vari-
ous reaction parameters were investigated for their
catalytic performances (Table 3).
Fig. 4. Molecular structure of complex C7. Thermal ellipsoids are shown
at 30% probability. Hydrogen atoms have been omitted for clarity.
2.3.1. Effects of reaction parameters
The catalytic system of C1/Et2AlCl was typically inves-
tigated with various reaction conditions, such as the molar
ratio of Al/Ni, reaction temperature and ethylene pressure.
The amount of Et2AlCl played an important role on the
catalytic properties of the system. When the Al/Ni molar
ratio was changed in the range of 100–500 (entries 4–8 in
Table 3), the highest activity was observed at the Al/Ni
ratio of 200 with 7.86 Â 104 g molÀ1(Ni) hÀ1 (entry 5 in
Table 3), while a higher molar ratio led to lower activity.
A possible reason could be that a threshold amount of
Et2AlCl as cocatalyst was necessary to activate the catalytic
precursor efficiently; however, too much of Et2AlCl might
over-reduce the nickel species and cause their deactivation.
This behavior is commonly observed in catalytic systems
using late-transition metal catalysts [8d]. The reaction tem-
perature also affected the activity, because the ethylene
oligomerization is a highly exothermic reaction, and the
solubility of ethylene in toluene and the stability of active
species are also affected by temperature. The optimum
activity was observed at the temperature of 20 °C (entry
5 in Table 3). Increasing the reaction temperature from
20 °C to 80 °C led to shut down the catalytic activities
(entries 5 and 9–11 in Table 3), which might be ascribed
to decomposition of the active species and lower ethylene
solubility at higher temperature.
Table 2
˚
Selected bond lengths (A) and angles (°) for complex C7
Bond lengths
Ni(1)–N(1)
Ni(1)–N(2)
Ni(1)–N(3)
Ni(1)–C(28)
N(1)–C(7)
N(1)–C(8)
N(3)–C(14)
N(3)–C(16)
O(1)–C(8)
1.895(3)
1.851(3)
1.928(3)
1.907(4)
1.470(5)
1.355(5)
1.320(5)
1.470(5)
1.237(5)
Ni(2)–N(4)
Ni(2)–N(5)
Ni(2)–N(6)
Ni(2)–C(65)
N(4)–C(44)
N(4)–C(45)
N(6)–C(51)
N(6)–C(53)
O(2)–C(45)
1.891(4)
1.851(4)
1.941(4)
1.897(4)
1.476(5)
1.362(5)
1.310(6)
1.442(6)
1.237(4)
Bond angles
N(2)–Ni(1)–N(1)
N(2)–Ni(1)–C(28)
N(1)–Ni(1)–C(28)
N(2)–Ni(1)–N(3)
N(1)–Ni(1)–N(3)
C(28)–Ni(1)–N(3)
82.71(2)
170.23(2)
97.38(2)
80.94(2)
162.57(2)
99.76(2)
N(5)–Ni(2)–N(4)
N(5)–Ni(2)–C(65)
N(4)–Ni(2)–C(65)
N(5)–Ni(2)–N(6)
N(4)–Ni(2)–N(6)
C(65)–Ni(2)–N(6)
83.06(2)
170.20(2)
96.08(2)
80.95(2)
162.98(2)
100.67(2)
Generally, the catalytic activity is increased at high eth-
ylene pressures; the same phenomenon was also observed
in this system. At 10 atm, in the presence of 200 equiv. of

M. Shen et al. / Journal of Organometallic Chemistry 693 (2008) 1683–1695
1687
Table 3
Results of ethylene oligomerization with catalysts C1–C10a
Entry
Catalyst
Cocatalyst
T (°C)
Al/Ni
Activityb
Oligomer distributionc
P
P
C4=
C
C6=
C
1
2
3
4
5
6
7
8
C1
C1
C1
C1
C1
C1
C1
C1
C1
C1
C1
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
MAO
MMAO
Et3Al
20
20
20
20
20
20
20
20
40
60
80
20
20
20
20
20
20
20
20
20
20
1000
1000
1000
100
200
250
300
500
200
200
200
200
200
200
200
200
200
200
200
200
200
0.46
0.71
1.95
4.83
7.86
7.47
5.72
4.07
7.22
6.94
5.21
62.5
0.36
0.33
4.36
0.41
0.39
3.26
4.05
7.82
0.65
97.1
2.9
0
100
98.7
1.3
6.6
4.5
10.8
4.9
4.6
5.8
6.4
6.8
8.6
13.9
10.8
11.5
12.6
8.9
6.5
5.9
7.5
3.8
Et2AlCl
Et2AlCl
Et2AlCl
Et2AlCl
Et2AlCl
Et2AlCl
Et2AlCl
Et2AlCl
Et2AlCl
Et2AlCl
Et2AlCl
Et2AlCl
Et2AlCl
Et2AlCl
Et2AlCl
Et2AlCl
Et2AlCl
Et2AlCl
93.4
95.5
89.2
95.1
96.4
94.2
93.6
93.2
91.4
86.1
89.2
88.5
87.4
92.1
93.5
94.1
92.5
96.2
9
10
11
12d
13
14
15
16
17
18
19
20
21
a
Conditions: 5 lmol of precatalyst; 30 min; 30 ml of toluene.
b
c
In units of 104 g (mol of Ni)À1 hÀ1
Determined by GC.
.
d
10 atm, 100 ml toluene.
Et2AlCl, complex C1 showed an activity of 6.25 Â
105 g molÀ1(Ni) hÀ1 for ethylene oligomerization (entry
12 in Table 3) which was almost 10 times higher than that
at ambient pressure.
system can lead to higher activity and longer lifetimes
[8,10]. Therefore, the oligomerization with C1/Et2AlCl
was carried out with different amount of PPh3. The results
are summarized in Table 4. In the presence of 1 equiv. PPh3
at ambient pressure, the catalytic activity of complex C1
was clearly improved (entry 2 in Table 4); however, larger
amounts of PPh3 obviously showed a decreased activity.
The most plausible effect of auxiliary ligand PPh3 is to
associate and dissociate from the nickel center, and this
affects the subsequent activation and protection of the
active sites. Besides, it was readily observed that the cata-
lytic activities increased under higher pressure with 1 equiv.
PPh3 (entry 6 in Table 4).
2.3.2. Effects of ligand environment
Changes in the ligand environments of these systems led
to different catalytic behaviors. The R1 substituents on the
imino-N aryl ring performed significant influence on their
activities. It was clearly observed that their catalytic
activities decreased with increasing the steric hindrance of
their ligands, the regulation was easily confirmed in the cat-
alytic systems of the complexes C3 (2,6-diisopropyl), C2
(2,6-diethyl) and C1 (2,6-dimethyl). Their activities
decreased in the order C3 < C2 < C1 (entries 5, 13 and 14
in Table 3). This could be attributed to the more bulky
groups at the ortho-positions of the imino-N aryl ring which
may prevent the addition of ethylene to the catalytic sites.
However, the oligomerization activities decreased in the
order of C7 < C4 < C1 (entries 5, 15 and 18 in Table 3) with
the increasing size of R3, and this case could be caused by
electronic influences of ligands. In contrast to the results
observed with C1 and C9 or C3 and C10 (entries 5 and 20,
14 and 21 in Table 3), there was little influence in the catalytic
activities upon changing R (phenyl or naphthyl) groups.
2.4. Kumada–Corriu reaction
Beyond the structural novelty of these nickel complexes,
their moderate catalytic activities toward ethylene oligo-
merization have made sense in understanding of their aca-
demic interests, but there are other interesting applications
of these catalysts. For example, C–C coupling is always an
important topic in organic synthesis, and more attention
has been paid to C–C bond formation between Grignard
reagents and aryl halides by Group 10 metal complexes
[15,16] since the pioneering work of Kumada and Corriu
[17]. In addition, those coupling reactions provide sub-
stances as building blocks for the synthesis of natural prod-
ucts, liquid crystals, polymers, and ligands in transition
metal complexes [18]. Recently, some square-planar coor-
2.3.3. Effects of the auxiliary ligand (PPh3)
Our previous studies on nickel catalysts have demon-
strated that the incorporation of PPh3 into the catalytic

1688
M. Shen et al. / Journal of Organometallic Chemistry 693 (2008) 1683–1695
Table 4
of toluene or THF (entries 1–3 in Table 5), in the conver-
sion yields and the selectivity for product A. Higher tem-
peratures give higher conversion yields (entries 3 and 4 in
Table 5). Increasing the amount of Grignard reagent gave
higher conversions based on bromobenzene, but more
byproduct D was obtained (entries 5–7 in Table 5). In most
cases, there was no byproduct C detected by GC, and no
exchange reactions between Grignard reagent and aryl
halides. These results obviously indicated that the titled
nickel complexes are effective catalysts for Kumada–Corriu
reaction at ambient temperature.
Ethylene reactivity with C1/Et2AlCl/PPh3a
Entry
P (atm)
PPh3 (equiv) Activityb Oligomer distributionc
P
P
C4=
C
C6=
C
1
2
3
4
5
6d
a
1
1
1
1
1
10
0.5
1
2
5
10
1
8.0
93.4
97.2
98.8
97.6
98.6
89.7
6.6
2.8
1.2
2.4
1.4
23.9
14.3
7.76
5.74
245
10.3
Conditions: 5 lmol of precatalyst; Al/Ni = 200; 30 min; 20 °C; 30 ml
of toluene.
b
In units of 104 g (mol of Ni)À1 hÀ1
Determined by GC.
.
c
2.5. Polymerization of methyl methacrylate (MMA)
d
100 ml toluene.
Recently, great progress has been made in using late-
transition metal-based complexes as catalysts in atom
transfer radical polymerization (ATRP) [20], and a series
of Ni(II) catalysts such as NiBr2(PPh3)2 [20e,20f] and
NiBr2(PBun3)2 [20g] can induce ATRP of methyl methacry-
late (MMA) in the presence of organic halides as an initia-
tor (such as CCl4, CCl3Br or ethyl-2-bromoisobutyrate).
Extensive studies revealed the formation of the carbon rad-
ical from R–X via a series of consecutive reversible redox
reactions between Ni(II) and Ni(III) species. Inspired by
these findings, the titled complexes were investigated for
polymerization of methyl methacrylate. The preliminary
results are summarized in Table 6.
dination nickel complexes were reported to be effective in
this reaction [16,18,19]. In order to explore the scope of
using the titled nickel complexes, their catalytic behaviors
in Kumada–Corriu reaction were investigated. These
results are collected in Table 5.
According to the data in Table 5, both of the aryl bro-
mides and chlorides react smoothly with the Grignard
reagent in the presence of a catalytic amount of the titled
nickel complexes. It was found that the mixture solvent
(1:1) of THF and toluene was superior to the pure solvent
Table 5
Kumada–Corriu reactions of Grignard reagent with aryl halidea
Ar
X
MgBr
Ar
+
+
H
Ar Ar
Ar
+
Ni-Cat
2
A
C
D
B
Entry
Catalyst (mol%)
Ar
X
Reaction conditions
Conversion of Ar–X(%)
Yield (%)b
A
B
D
1c
2d
3
C9 (1%)
C9 (1%)
C9 (1%)
C9 (1%)
C9 (1%)
C9 (1%)
C1 (1%)
C3 (1%)
C10 (1%)
C3 (1%)
C9 (1%)
C3 (4%)
C9 (4%)
C3 (1%)
C9 (1%)
C3 (4%)
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Cl
Cl
Br
Br
Cl
RT, 24 h
RT, 24 h
RT, 24 h
80 °C, 24 h
RT, 24 h
RT, 24 h
RT, 24 h
RT, 24 h
RT, 24 h
RT, 24 h
RT, 24 h
RT, 24 h
RT, 24 h
RT, 24 h
80 °C, 24 h
80 °C, 24 h
79
82
86
91
64
100
84
91
96
90
87
94
96
56
75
80
51
60
62
70
45
74
57
63
68
65
62
61
71
42
54
66
18
14
20
19
16
25
30
22
21
22
15
17
12
8
11
27
24
26
8
31
24
18
21
19
21
20
24
16
18
14
4
5e
6f
7
8
9
Ph
10
11
12
13
14
15
16
a
Naph
Naph
Ph
Ph
o-MePh
p-MeOPh
Naph
16
9
Conditions: 1.5 equiv. Grignard reagent; a mixed solvents of THF and toluene (1:1).
b
c
d
e
f
GC yield.
THF as solvent.
Toluene as solvent.
1.0 equiv. Grignard reagent.
2.0 equiv. Grignard reagent.

M. Shen et al. / Journal of Organometallic Chemistry 693 (2008) 1683–1695
1689
Table 6
were determined with a digital electrothermal apparatus
without calibration. The IR spectra were recorded on a
Perkin–Elmer FT-IR 2000 spectrophotometer using
The MMA polymerization with nickel complex/ethyl-2-bromoisobutyrate
systema
T (°C) Yield (%) Mbn
Mw/Mbn
1
KBr disc in the range of 4000–400 cmÀ1. The H and 13C
Entry
Catalyst
MMA:
Cat:initiator
NMR spectra were recorded on
a Bruker DMX-
1
2
3
4
5
6
7
8
a
C9
250:1:1
250:1:1
250:1:0.5
250:1:2
250:1:1
250:1:1
250:1:1
250:1:1
80
80
80
80
90
90
90
90
26.4
21.2
23.8
73.2
93.2
66.3
0
14173 1.85
300 MHz instrument at ambient temperature using TMS
as an internal standard. Splitting patterns are designated
as follows: s, singlet; bs, broad singlet; d, doublet; dd, dou-
ble doublet; t, triplet; m, multiplet. The elemental analyses
were performed on a Flash EA 1112 microanalyser. Distri-
bution of oligomers obtained was measured on a Varian
VISTA 6000 GC spectrometer and a HP 5971A GC–MS
detector.
C10
C9
14032 1.89
12931 1.86
34302 3.13
45632 2.00
41201 2.01
C9
C9
C10
C1
–
–
–
–
C3
0
Conditions: 2 ml of MMA; 5 ml of toluene; 24 h.
After precipitation in MeOH, calculated from GPC, using PMMA
b
THF and toluene were refluxed over sodium-benzophe-
none until purple color appeared and were distilled under
nitrogen atmosphere prior to use. CH2Cl2 and pentane
were distilled under nitrogen from CaH2. NaH was washed
with n-hexane (4 Â 20 ml) and dried before use. Trans-
[NiCl(Naph)(PPh3)2] [21] and trans-[NiCl(Ph)(PPh3)2] [22]
were prepared according to literature procedure. Methyl-
aluminoxane (MAO, 1.46 M in toluene) and modified
methylaluminoxane (MMAO, 1.93 M in heptane, 3A) were
purchased from Akzo Nobel Corp. Diethylaluminum chlo-
ride (Et2AlCl, 1.9 M in hexane) was purchased from Acros
Chemicals. All other chemicals were obtained commer-
cially and were used without further purification unless sta-
ted otherwise.
standard samples.
In proper conditions, the phenyl nickel complex showed
considerable activity as observed in Entry 5 in Table 6 for
the polymerization of MMA. However, the naphthenyl
nickel analogues appear to have no activity (entries 7 and
8 in Table 6). This maybe due to the fact that naphthenyl
nickel complexes are more difficult to transform to the
Ni(III) species. The preliminary results show that these
neutral Ni(II) complexes with metal–carbon bonds are
potentially effective catalysts for the ATRP of MMA.
Unfortunately, the ability of this system for inducing
ATRP of MMA is relatively low compared to reported sys-
tems [20e,20d,20f], the polydispersity was relatively broad.
Further investigations are progressing on controlling the
resultant polyMMAs with desiring molecular weights and
distributions.
4.2. Synthesis of N-alkyl-6-(1-(arylimino)ethyl)-
picolinamide
Synthesis of (E)-N-butyl-6-(1-(2,6-dimethylphenylimi-
no)ethyl)picolinamide (L1): (E)-Ethyl 6-(1-(2,6-dimethyl-
phenylimino)ethyl)picolinate (0.593 g, 2 mmol) and
1-butylamine (0.228 g, 3 mmol) were dissolved in 30 ml
methanol and further stirred for 12 h. The compound,
(E)-N-butyl-6-(1-(2,6-dimethylphenylimino)ethyl)picolina-
mide, was purified by column chromatography (silica gel,
petroleum ether/ethyl acetate = 7/1) and obtained as yel-
low solid in 94% yield (0.61 g). Mp: 101–103 °C. 1H
NMR (300 MHz, CDCl3): d 8.52 (d, 1H, J = 7.9 Hz, Py
Hm), 8.31 (d, 1H, J = 7.9 Hz, Py Hm), 8.04 (br s, 1H),
7.97 (t, 1H, J = 7.9 Hz, Py Hp), 7.08 (d, 2H, J = 7.5 Hz),
6.95 (t, 1H, J = 7.5 Hz), 3.52 (m, 2H), 2.20 (s, 3H), 2.03
(s, 6H), 1.65 (m, 2H), 1.47 (m, 2H), 0.98 (t, 3H). 13C
NMR (75 MHz, CDCl3): d 166.7, 164.2, 153.9, 148.7,
147.4, 137.5, 127.1, 124.6, 123.2, 122.8, 122.6, 38.6, 30.9,
19.3, 16.4, 15.2, 12.4. FT-IR (KBr disc, cmÀ1): 3331,
3070, 2936, 2863, 1653 (mC@O), 1643 (mC@N), 1531, 1467,
1208, 768, 691. Anal. Calc. for C20H25N3O: C, 74.27; H,
7.79; N, 12.99. Found: C, 74.57; H, 7.95; N, 12.86%.
Synthesis of (E)-N-butyl-6-(1-(2,6-diethylphenylimi-
no)ethyl)picolinamide (L2): The reaction of (E)-ethyl-
3. Conclusion
A series of novel N^N^N tridentate neutral nickel
complexes, arylnickel N-alkyl-6-(1-(arylimino)ethyl)picoli-
namides, were synthesized and characterized. X-ray struc-
tural determinations revealed that the complexes adopt a
distorted square-planar coordination around the central
metal atom. Activated by Et2AlCl, all nickel complexes
exhibited moderate catalytic activities for ethylene oligo-
merization. Their catalytic activities decreased with
increasing steric hindrance of their ligands. The addition
of PPh3 as an auxiliary ligand led to increase the catalytic
activity. These complexes also performed moderate cata-
lytic activities in Kumada–Corriu reaction and consider-
able conversion yields for polymerization of methyl
methacrylate.
4. Experimental
4.1. General considerations
6-(1-(2,6-diethylphenylimino)ethyl)picolinate (0.649 g,
2
All manipulations for air- or/and moisture-sensitive
compounds were carried out under a nitrogen atmosphere
using standard Schlenk techniques. Melting points (Mp)
mmol) and 1-butylamine (0.228 g, 3 mmol) in methanol gave
(E)-N-butyl-6-(1-(2,6-diethylphenylimino)ethyl)picolinamide
1
as yellow solid in 92% yield (0.65 g). Mp: 122–124 °C. H

1690
M. Shen et al. / Journal of Organometallic Chemistry 693 (2008) 1683–1695
NMR (300 MHz, CDCl3): d 8.51 (d, 1H, J = 7.9 Hz, Py
Hm), 8.31 (d, 1H, J = 7.9 Hz, Py Hm), 8.04 (br s, 1H),
7.97 (t, 1H, J = 7.9 Hz, Py Hp), 7.12 (d, 2H, J = 5.6 Hz),
7.05 (t, 1H, J = 7.5 Hz), 3.52 (m, 2H), 2.36 (m, 4H), 2.21
(s, 3H), 1.66 (m, 2H), 1.45 (m, 2H), 1.13 (t, 6H), 0.98 (t,
3H). 13C NMR (75 MHz, CDCl3): d 164.7, 162.5, 153.7,
148.1, 146.4, 136.7, 129.9, 124.8, 122.2, 121.9, 37.9, 30.7,
23.4, 19.0, 15.4, 12.4. FT-IR (KBr disc, cmÀ1): 3352,
3053, 2964, 2932, 2871, 1657 (mC@O), 1640 (mC@N), 1527,
1452, 1111, 773, 684. Anal. Calc. for C22H29N3O: C,
75.18; H, 8.32; N, 11.96. Found: C, 75.08; H, 8.30; N,
11.74%.
2H), 1.26–1.45 (m, 12H), 0.85 (t, 3H). 13C NMR
(75 MHz, CDCl3): d 165.9, 163.8, 154.6, 148.9, 146.1,
137.8, 135.5, 123.7, 13.3, 122.9, 39.4, 31.7, 29.7, 29.1,
28.2, 26.9, 23.0, 22.7, 22.5, 16.9, 14.0. FT-IR (KBr disc,
cmÀ1): 3332, 3069, 2956, 2937, 2864, 1650 (mC@O), 1645
(mC@N), 1529, 1207, 768. Anal. Calc. for C28H41N3O:
C, 77.20; H, 9.49; N, 9.65. Found: C, 77.42; H, 9.13; N,
9.72%.
Synthesis of (E)-N-benzyl-6-(1-(2,6-dimethylphenylimi-
no)ethyl)picolinamide (L6): The reaction of (E)-ethyl-6-
(1-(2,6-dimethylphenylimino)ethyl)picolinate
(0.593 g,
2 mmol) and phenylmethanamine (0.321 g, 3 mmol) in
methanol gave (E)-N-benzyl-6-(1-(2,6-dimethylphenylimi-
no)ethyl)picolinamide as yellow solid in 93% yield
Synthesis of (E)-N-butyl-6-(1-(2,6-diisopropylphenyl-
imino)ethyl)picolinamide (L3): The reaction of (E)-ethyl
6-(1-(2,6-diisopropylphenylimino)ethyl)picolinate (0.702 g,
2 mmol) and 1-butylamine (0.228 g, 3 mmol) in methanol
gave (E)-N-butyl-6-(1-(2,6-diisopropyylphenylimino)ethyl)-
picolinamide as yellow solid in 96% yield (0.73 g). Mp.:
1
(0.67 g). Mp.: 127–129 °C. H NMR (300 MHz, CDCl3):
d 8.54 (d, 1H, J = 7.9 Hz, Py Hm), 8.36 (m, 3H), 7.99
(m, 1H), 7.33–7.40 (m, 5H), 7.07 (d, 2H), 6.94 (t, 1H),
4.74 (d, 2H), 2.15 (s, 3H), 2.02 (s, 6H). 13C NMR
(75 MHz, CDCl3): d 164.8, 162.9, 153.6, 147.5, 147.2,
137.1, 136.7, 127.5, 127.0, 126.7, 126.3, 126.2, 124.0,
122.6, 122.5, 122.0, 42.2, 16.7, 13.3, 15.2. FT-IR (KBr disc,
cmÀ1): 3335, 3066, 2939, 2854, 1671 (mC@O), 1650 (mC@N),
1524, 1455, 1436, 1208, 768, 702. Anal. Calc. for
C23H23N3O: C, 77.28; H, 6.49; N, 11.76. Found: C,
77.42; H, 6.13; N, 11.72%.
1
142–144 °C. H NMR (300 MHz, CDCl3): d 8.51 (d, 1H,
J = 7.9 Hz, Py Hm), 8.32 (d, 1H, J = 7.9 Hz, Py Hm),
8.06 (br s, 1H), 7.98 (t, 1H, J = 7.9 Hz, Py Hp), 7.11–7.19
(m, 3H), 3.52 (m, 2H), 2.71 (m, 2H), 2.24 (s, 3H), 1.66
(m, 2H), 1.45 (m, 2H), 1.15 (d, 12H), 0.98 (t, 3H). 13C
NMR (75 MHz, CDCl3): d 164.9, 162.5, 153.6, 148.1,
145.1, 136.7, 134.5, 122.6, 122.3, 121.9, 121.8, 37.9, 30.7,
27.1, 21.8, 21.4, 19.0, 15.7, 12.4. FT-IR (KBr disc, cmÀ1):
3385, 3062, 2959, 2868, 1677 (mC@O), 1645 (mC@N), 1525,
1451, 777, 636. Anal. Calc. for C24H33N3O Á 0.5H2O: C,
74.19; H, 8.82; N, 10.81. Found: C, 74.67; H, 8.45; N,
10.16%.
Synthesis of (E)-N-benzyl-6-(1-(2,6-diisopropylphenyl-
imino)ethyl)picolinamide (L7): The reaction of (E)-ethyl-
6-(1-(2,6-diisopropylphenylimino)ethyl)picolinate (0.702 g,
2 mmol) and phenylmethanamine (0.321 g, 3 mmol) in
methanol gave (E)-N-benzyl-6-(1-(2,6-diisopropylphenyli-
mino)ethyl)picolinamide as yellow solid in 93% yield
Synthesis of (E)-6-(1-(2,6-dimethylphenylimino)ethyl)-
N-octylpicolinamide (L4): The reaction of (E)-ethyl
1
(0.77 g). Mp.: 182–184 °C. H NMR (300 MHz, CDCl3):
6-(1-(2,6-dimethylphenylimino)ethyl)picolinate
(0.593 g,
d 8.53 (d, 1H, J = 7.9 Hz, Py Hm), 8.36 (m, 3H), 8.00 (m,
1H), 7.29–7.41 (m, 5H); 7.16 (d, 2H), 7.08 (t, 1H), 4.74
(d, 2H), 4.74 (d, 2H), 2.70 (m, 2H), 2.18 (s, 3H), 1.13 (d,
12H). 13C NMR (75 MHz, CDCl3): d 164.9, 162.8, 153.7,
147.7, 145.0, 137.7, 136.8, 134.5, 127.4, 126.2, 126.1,
122.6, 122.2, 121.8, 42.0, 27.1, 21.8, 214, 15.8. FT-IR
(KBr disc, cmÀ1): 3387, 3068, 2960, 2866, 1674, 1649,
1517, 1451, 1255, 773, 698. Anal. Calc. for C27H31N3O:
C, 78.42; H, 7.56; N, 10.16; O, 4.48. Found: C, 78.62; H,
7.23; N, 10.02%.
2 mmol) and 1-octylamine (0.388 g, 3 mmol) in methanol
gave (E)-6-(1-(2,6-dimethyl phenylimino)ethyl)-N-octylpic-
1
olinamide as yellow oil in 85% yield (0.64 g). H NMR
(300 MHz, CDCl3): d 8.51 (d, 1H, J = 7.9 Hz, Py Hm),
8.31 (d, 1H, J = 7.9 Hz, Py Hm), 8.04 (m, 1H), 7.97 (t,
1H, J = 7.9 Hz, Py Hp), 7.08 (d, 2H), 6.95 (t, 1H), 3.51
(m, 2H), 2.21 (s, 3H), 2.03 (s, 6H), 0.85 (t, 3H), 1.20–1.45
(m, 12H), 13C NMR (75 MHz, CDCl3): d 165.9, 163.7,
154.7, 149.2, 148.5, 137.7, 128.0, 127.8, 124.9, 123.4,
123.3, 39.5, 31.8, 29.8, 29.3, 29.2, 27.0, 22.6, 20.7, 17.8,
17.5, 16.2, 14.0. FT-IR (KBr disc, cmÀ1): 3400, 3019,
2926, 2856, 1677 (mC@O), 1643 (mC@N), 1524, 1450, 1206,
836, 764. Anal. Calc. for C24H33N3O: C, 75.95; H, 8.76;
N, 10.07. Found: C, 75.62; H, 8.73; N, 10.12%.
Synthesis of (E)-6-(1-(2,6-diisopropylphenylimino)ethyl)-
N-octylpicolinamide (L5): The reaction of (E)-ethyl 6-
(1-(2,6-diisopropylphenylimino)ethyl)picolinate (0.702 g, 2
mmol) and 1-octylamine (0.388 g, 3 mmol) in methanol
gave (E)-6-(1-(2,6-diisopropyl phenylimino)ethyl)- N-octyl-
picolinamide as yellow solid in 86% yield (0.75 g). Mp:
80–82 °C. 1H NMR (300 MHz, CDCl3): d 8.51 (d, 1H,
J = 7.9 Hz, Py Hm), 8.32 (d, 1H, J = 7.9 Hz, Py Hm),
8.06 (br s, 1H), 7.98 (t, 1H, J = 7.9 Hz, Py Hp), 7.11–7.19
(m, 3H), 3.51 (m, 2H), 2.71(m, 2H), 2.23 (s, 3H), 1.67 (m,
Synthesis of (E)-N-butyl-6-(1-(mesitylimino)ethyl)pico-
linamide (L8): The reaction of (E)-ethyl 6-(1-(mesitylimi-
no)ethyl)picolinate (0.620 g, 2 mmol) and 1-butylamine
(0.228 g, 3 mmol) in methanol gave (E)-N-butyl-6-(1-(mesi-
tylimino)ethyl)picolinamide as yellow solid in 86% yield
1
(0.58 g). Mp.: 97–99 °C. H NMR (300 MHz, CDCl3): d
8.51 (d, 1H, J = 7.9 Hz, Py Hm), 8.30 (d, 1H, J = 7.9 Hz,
Py Hm), 8.03 (br s, 1H), 7.98 (t, 1H, J = 7.9 Hz, Py Hp),
6.90 (s, 2H), 3.51 (m, 2H), 2.29 (s, 3H), 2.19 (s, 3H), 2.00
(s, 6H), 1.64 (m, 2H), 1.44 (m, 2H), 0.98 (t, 3H). 13C
NMR (75 MHz, CDCl3): d 166.7, 165.2, 156.4, 147.6,
147.4, 137.3, 131.0, 126.1, 125.9, 124.3, 123.5, 61.9, 24.5,
16.8, 14.3, 13.7. IR (KBr, cmÀ1): 1722, 1640, 1580, 1540,
1454, 1394. FT-IR (KBr disc, cmÀ1): 3386, 3083, 2933,
2872, 1678 (mC@O), 1645 (mC@N), 1526, 1481, 1363, 1217,

M. Shen et al. / Journal of Organometallic Chemistry 693 (2008) 1683–1695
1691
771, 667. Anal. Calc. for C21H27N3O: C, 74.74; H, 8.06; N,
12.45. Found: C, 74.42; H, 8.36; N, 12.69%.
1-Naphthylnickel N-butyl-6-(1-(2,6-diisopropylphenyli-
mino)ethyl)picolinamide (C3): In similar manner
a
described for C1, the complex C3 was obtained from the
reaction of trans-[NiCl(Naph)(PPh3)2] and L3 as a brown
powder in 53% yield. 1H NMR (300 MHz, CDCl3): d
9.21 (d, 1H, J = 7.89 Hz), 8.05 (m, 2H), 7.63 (d, 1H,
J = 7.23), 7.48 (m, 5H), 7.18–7.27 (m, 1H), 7.17 (d, 1H),
7.04 (m, 3H),6.92 (d, 1H, J = 7.53), 6.67 (t, 1H,
J = 7.38), 6.57 (d, 1H, J = 7.56), 3.24 (m, 1H), 3.05 (m,
1H), 2.03 (s, 3H), 1.80 (d, 4H), 1.39 (m, 1H), 1.16 (d,
4H), 1.06 (m, 2H), 0.78 (m, 2H), 0.71 (d, 4H), 0.41 (t,
3H), À0.34 (d, 4H). 13C NMR (75 MHz, CDCl3): d
171.7, 170.5, 157.5, 154.1, 149.7, 140.9, 140.5, 139.5,
138.7, 133.4, 133.3, 132.1, 127.7, 127.3, 123.9, 123.7,
123.5, 123.4, 123.3, 122.3, 122.2, 45.7, 33.0, 28.7, 24.5,
24.3, 21.0, 20.2, 18.9, 13.8. FT-IR (KBr disc, cmÀ1):
3032, 2955, 2866, 1609, 1597, 1545, 1432, 1370, 1193,
786, 759. Anal. Calc. for C34H39N3NiO: C, 72.36; H,
6.97; N, 7.45. Found: C, 71.10; H, 6.92; N, 7.47%.
1-Naphthylnickel N-octyl-6-(1-(2,6-dimethylphenylimi-
no)ethyl)picolinamide (C4): In a similar manner described
for C1, the complex C4 was obtained from the reaction of
trans-[NiCl(Naph)(PPh3)2] and L4 as a brown powder in
43% yield. 1H NMR (300 MHz, CDCl3): d 9.22 (d,
J = 7.56, 1H), 8.07 (m, 3H), 7.67 (m, 2H), 7.46 (m, 2H),
7.05 (m, 2H), 6.83 (d, J = 7.56, 1H), 6.70 (m, 3H), 6.36
(d, J = 7.53, 1H), 2.91 (m, 1H), 2.37 (s, 3H), 2.32 (m,
1H), 1.89 (s, 3H), 1.63 (s, 3H), 0.90–1.40 (m, 12H), 0.77
(t,3H). 13C NMR (75 MHz, CDCl3): d 171.5, 170.7,
159.4, 154.0, 149.8, 144.7, 140.2, 139.7, 133.3, 132.8,
132.7, 132.5, 128.4, 128.2, 128.1, 128.0, 127.6, 126.1,
123.9, 123.3, 123.1, 122.9, 122.2, 46.9, 31.8, 30.7, 29.1,
27.1, 22.7, 18.9, 17.8, 16.5, 14.2. FT-IR (KBr disc, cmÀ1):
3042, 2955, 2946, 1618, 1596, 1463, 1371, 1117, 779, 758.
Anal. Calc. for C34H39N3NiO: C, 72.36; H, 6.97; N, 7.45.
Found: C, 72.71; H, 6.90; N, 7.67%.
4.3. Synthesis of complexes
1-Naphthylnickel N-butyl-6-(1-(2,6-dimethylphenylimi-
no)ethyl)picolinamide (C1): A flame-dried Schlenk tube
was charged with L1 (323 mg, 1 mmol) and sodium hydride
(72 mg, 3 mmol) under nitrogen. THF (10 ml) was added
to the mixture at 0 °C. Many bubbles were immediately
produced. The resulting mixture was stirred at room tem-
perature for 1 h, filtered, and evaporated. The Na salt
was immediately used in the next step without further puri-
fication. Solid
trans-[NiCl(Naph)(PPh3)2] (746 mg,
1 mmol) was added to the Schlenk tube under positive
nitrogen flow. The mixture was charged with toluene
(30 ml) and stirred at 20 °C for 12 h. Then, the reaction
mixture was filtered and the filtrate was concentrated in
vacuo to ca. 5 ml. Hexane (50 ml) was added to this solu-
tion. A solid was precipitated and isolated by cannula fil-
1
tration to get a brown powder in 59% yield (345 mg). H
NMR (300 MHz, CDCl3): d 9.23 (d, 1H, J = 7.38 Hz),
8.08 (t, 1H, J = 7.62 Hz), 8.03 (d, 1H); 7.66 (d, 1H,
J = 7.59), 7.47 (d, 1H, J = 7.5 Hz), 7.07 (d, 1H, J = 7.98),
6.84 (d, 1H, J = 7.77 Hz), 6.73 (m, 2H), 6.37 (d, 1H),
7.26–7.29 (m, 3H), 2.94 (m, 1H, J = 12.06, NCH2), 2.38
(s, 3H), 1.85 (s, 3H), 1.83 (m, 1H, NCH2), 1.64 (s, 3H),
1.11 (m, 2H), 0.76 (m, 2H), 0.39 (t, 3H). 13C NMR
(75 MHz, CDCl3): d 171.4, 170.8, 159.5, 154.0, 149.8,
144.7, 139.6, 140.2, 139.6, 132.7, 132.5, 132.2, 132.1,
128.7, 128.5, 128.4, 128.0, 127.6, 126.1, 123.9, 123.2,
123.1, 122.8, 122.1, 46.5, 32.9, 20.2, 18.9, 17.8, 16.5, 13.7.
FT-IR (KBr disc, cmÀ1): 3040, 2956, 1613, 1602, 1546,
1432, 1371, 1199, 766. Anal. Calc. for C30H31N3NiO Á
0.5H2O: C, 69.66; H, 6.24; N,8.12. Found: C, 69.57; H,
6.27; N, 8.02%.
1-Naphthylnickel
no)ethyl)picolinamide (C2): In
N-butyl-6-(1-(2,6-diethylphenylimi-
similar manner
1-Naphthylnickel N-octyl-6-(1-(2,6-diisopropylphenyli-
mino)ethyl)picolinamide (C5): In a similar manner
a
described for C1, the complex C2 was obtained from
the reaction of trans-[NiCl(Naph)(PPh3)2] and L2 as a
brown powder in 45% yield. 1H NMR (300 MHz,
CDCl3): d 9.20 (d, 1H, J = 7.89 Hz), 8.08 (m, 2H), 7.66
(d, 1H, J = 7.38), 7.45 (d, 1H), 7.18–7.27 (m, 1H,
J = 7.23), 7.16 (d, 1H, J = 6.54), 7.03 (d, 1H, J = 7.89),
6.92 (d, 1H, J = 7.53), 6.82 (t, 1H, J = 7.56), 6.68 (t,
1H, J = 7.38), 6.41 (d, 1H, J = 7.56), 3.05 (m, 1H), 2.98
(m, 1H), 2.58 (m, 1H), 2.18 (m, 1H), 1.96 (m, 1H), 1.89
(s, 3H), 1.83 (m, 1H), 1.34 (t, 3H), 1.11 (m, 2H), 0.72
(m, 2H), 0.50 (t, 3H). 0.37 (t, 3H). 13C NMR (75 MHz,
CDCl3): d 171.7, 170.8, 159.7, 153.8, 149.8, 143.5, 140.0,
139.8, 133.6, 133.3, 132.9, 132.7, 132.4, 127.6, 126.4,
124.7, 124.6, 123.8, 123.2, 123.0, 122.4, 122.1, 32.9, 24.6,
23.5, 20.2, 16.6, 17.0, 13.7, 13.5, 12.3. FT-IR (KBr disc,
cmÀ1): 3038, 2959, 2928, 1613, 1590, 1546, 1435, 1371,
787, 760. Anal. Calc. for C32H35N3NiO Á 0.5EtOH: C,
70.86; H, 6.85; N, 7.51. Found: C, 71.10; H, 6.92; N,
7.47%.
described for C1, the complex C5 was obtained from the
reaction of trans-[NiCl(Naph)(PPh3)2] and L5 as a brown
powder in 51% yield. 1H NMR (300 MHz, CDCl3): d
9.31 (d, 1H, J = 7.56 Hz), 8.08 (m, 3H), 7.66 (m, 2H),
7.45 (m, 2H), 7.00–7.27 (m, 2H),6.92 (d, 1H, J = 7.53),
6.67 (t, 1H, J = 7.38), 6.57 (d, 1H, J = 7.2), 3.24 (m, 1H),
3.00 (m, 1H), 2.65 (m, 1H), 2.01 (s, 3H), 1.93 (m, 1H),
1.80 (d, 3H), 0.72–1.82 (m, 21H), À0.34 (d, 3H). 13C
NMR (75 MHz, CDCl3): d 171.8, 170.5, 157.6, 154.2,
149.8, 142.5, 140.9, 140.6, 139.6,138.7, 134.7, 134.6,
133.5, 132.2, 127.7, 127.3, 126.4, 124.0, 123.6, 123.2,
123.0, 122.3, 122.2, 31.9, 30.9, 30.6, 29.4, 29.3, 29.0, 28.8,
27.1, 24.9, 24.5, 24.4, 22.7, 21.0, 18.9, 14.2 FT-IR (KBr
disc, cmÀ1): 3051, 2958, 2925, 2854, 1613, 1591, 1462,
1436, 1371, 1119, 786, 761. Anal. Calc. for
C38H47N3NiO Á 0.5H2O: C, 72.50; H, 7.69; N, 6.68. Found:
C, 72.57; H, 6.37; N, 7.02%.
1-Naphthylnickel N-benzyl-6-(1-(2,6-dimethylphenylimi-
no)ethyl)picolinamide (C6): In a similar manner described

1692
M. Shen et al. / Journal of Organometallic Chemistry 693 (2008) 1683–1695
for C1, the complex C6 was obtained from the reaction of
trans-[NiCl(Naph)(PPh3)2] and L6 as a brown powder in
48% yield (298 mg). H NMR (300 MHz): d 9.16 (d, 1H),
1.17 (m, 2H); 0.90 (m, 2H); 0.58 (t, 3H). 13C NMR
(75 MHz, CDCl3): d170.8,170.4, 156.8, 153.9, 149.5,
144.8, 139.3, 135.0, 128.2, 127.7, 126.2, 124.8, 122.7,
122.0, 121.7, 45.8, 32.3, 20.2, 18.4, 16.3, 13.7. FT-IR
(KBr disc, cmÀ1): 3048, 3955, 2927, 1612, 1590, 1560,
1416, 761, 733, 699. Anal. Calc. for C26H29N3NiO: C,
68.15; H, 6.38; N, 9.17. Found: C, 68.10; H, 6.72; N, 9.47%.
Phenylnickel N-butyl-6-(1-(2,6-diisopropylphenylimino)-
ethyl)picolinamide (C10): In a similar manner described
for C1, the complex C10 was obtained from the reaction
of trans-[NiCl(phenyl)(PPh3)2] and L3 as a brown powder
in 49% yield. 1H NMR (300 MHz, CDCl3): d 8.02 (m,
2H), 7.63 (d, 1H, J = 7.2), 7.11 (m, 2H), 6.98 (d, 2H)
6.60 (m, 3H), 3.10 (m, 2H), 2.62 (t, 2H), 1.98 (s, 3H),
1.21 (d, 6H), 1.15 (m, 2H), 1.02 (d, 2H), 0.95 (m, 2H),
0.58 (t, 3H). 13C NMR (75 MHz, CDCl3): d 171.5, 170.4,
155.0, 154.1, 149.7, 142.5, 139.5, 136.3, 127.7, 125.0,
123.6, 123.1, 122.4, 122.1, 45.4, 32.6, 28.8, 24.5, 23.4,
20.3, 18.7, 14.0. FT-IR (KBr disc, cmÀ1): 3045, 2957,
2924, 2868, 1610, 1593, 1560, 1421, 757, 733, 698. Anal.
Calc. for C30H37N3NiO: C, 70.06; H, 7.25; N, 8.17. Found:
C, 71.10; H, 7.42; N, 8.47%.
1
8.06 (m, 2H), 7.65 (d, 1H, J = 6.87), 7.46 (m, 1H), 6.80–
7.25 (m, 10H),6.63 (m, 2H), 6.33 (d, 1H, J = 7.53), 4.31
(d, 1H, J = 13.74), 3.01 (d, 1H, J = 13.38), 2.31 (s, 3H),
1.86 (s, 3H), 1.60 (s, 3H). 13C NMR (75 MHz, CDCl3): d
171.7, 154.3, 150.7, 140.1, 133.3, 129.6, 128.5, 128.3,
128.2, 127.9, 127.6, 126.4, 125.7, 124.1, 123.7, 123.4,
123.3, 122.7, 122.5, 50.3, 19.1, 18.1, 16.8. FT-IR (KBr disc,
cmÀ1): 3032, 2908, 1615, 1597, 1436, 1190, 1118, 696, 541.
Anal. Calc. for C33H29N3NiO: C, 73.09; H, 5.39; N, 7.75.
Found: C, 73.10; H, 5.22; N, 7.47%.
1-Naphthylnickel N-benzyl-6-(1-(2,6-diisopropylphenyl-
imino)ethyl)picolinamide (C7): In
a similar manner
described for C1, the complex C7 was obtained from the
reaction of trans-[NiCl(Naph)(PPh3)2] and L7 as a brown
powder in 57% yield. 1H NMR (300 MHz, CDCl3): d
9.22 (d, 1H, J = 6.87 Hz), 8.06 (m, 2H), 7.82 (m, 1H),
7.7–7.2 (m, 4H), 7.07 (d, 1H), 6.74 (t, J = 7.38, 1H), 6.63
(s, 1H), 6.15 (s, 1H), 2.95 (m, 1H), 2.31 (s, 3H), 2.01 (s,
3H), 1.57 (s, 3H), 1.12 (m, 2H), 0.75 (m, 2H), 0.39 (t,
3H). 13C NMR (75 MHz, CDCl3): d 171.7, 156.6, 153.7,
149.8, 142.6, 142.3, 140.7, 140.6, 139.6, 138.7, 134.0,
133.3, 131.8, 128.2, 127.8, 127.4, 125.4, 124.0, 123.8,
123.6, 123.5, 123.2, 122.5, 122.4, 73.4, 49.3, 28.8, 24.9,
24.4, 24.2, 18.8. FT-IR (KBr disc, cmÀ1): 3055, 2961,
1615, 1593, 1547, 1437, 1371, 786, 760. Anal. Calc. for
C37H37N3NiO Á 0.5H2O Á 0.5Et2O: C, 72.68; H, 6.73; N,
6.52; Ni, 9.11. Found: C, 72.72; H, 6.31; N, 6.86%.
4.4. Procedure for ethylene oligomerization
Ethylene oligomerization at 1 atm of ethylene pressure
was carried out as follows: the catalyst precursor was dis-
solved in toluene in a Schlenk tube, and the reaction solution
was stirred with a magnetic stir under ethylene atmosphere
(1 atm) with the reaction temperature being controlled by
a water bath. The required amount of cocatalyst (MAO,
MMAO, or Et2AlCl) and the solution of PPh3 were added
by a syringe. After the reaction was carried out of the
required period, the reactor was cold to lower temperature
in ice-bath. Then a small amount of the reaction solution
was collected and terminated by the addition of cold 10%
aqueous hydrogen chloride. The organic layer was analyzed
quickly by gas chromatography (GC) for determining the
composition and mass distribution of oligomers.
High-pressure ethylene oligomerization was performed
in a stainless steel autoclave (0.5 L capacity) equipped with
gas ballast through a solenoid clave for continuous feeding
of ethylene at constant pressure. A 100 ml amount of tolu-
ene containing the catalyst precursor was transferred into
the fully dried reactor under a nitrogen atmosphere. The
required amount of cocatalyst (Et2AlCl) was then injected
into the reactor using a syringe. Then the reactor was pres-
surized to the desired pressure (10 atm). After the reaction
mixture was stirred for the desired period of time, the reac-
tion was stopped without ethylene inputting. Then the
autoclave was cold in ice-bath for an hour, the pressure
was released. A small amount of the reaction solution
was collected and terminated by the addition of cold 10%
aqueous hydrogen chloride. C4 and C6 were dissolved in
organic layer which was analyzed quickly by gas chroma-
tography (GC) for determining the composition and mass
distribution of oligomers obtained.
1-Naphthylnickel N-butyl-6-(1-(mesitylimino)ethyl)pic-
olinamide (C8): In a similar manner described for C1,
the complex C8 was obtained from the reaction of trans-
[NiCl(Naph)(PPh3)2] and L8 as a brown powder in 61%
1
yield (298 mg). H NMR (300 MHz, CDCl3): d 9.31 (d,
1H, J = 7.89 Hz), 8.08 (m, 2H), 7.66 (m, 3H), 7.45 (d,
1H), 7.18–7.27 (m, 1H, J = 7.23), 7.16 (d, 1H, J = 6.54),
7.03 (d, 1H, J = 7.89), 6.92 (d, 1H, J = 7.53), 6.82 (t, 1H,
J = 7.56), 6.68 (t, 1H, J = 7.38), 6.41(d, 1H, J = 7.56),
3.05 (m, 1H), 2.98 (m, 1H), 2.58 (m, 1H), 2.18 (m, 1H),
1.96 (m, 1H), 1.89 (s, 3H), 1.83 (m, 1H), 1.34 (t, 3H),
1.11 (m, 2H), 0.72 (m, 2H), 0.50 (t, 3H), 0.37 (t, 3H). 13C
NMR (75 MHz, CDCl3): d 171.7, 170.5, 157.5, 154.1,
149.7, 140.9, 140.5, 139.5, 138.7, 133.4, 133.3, 132.1,
127.7, 127.3, 123.9, 123.7, 123.5, 123.4, 123.3, 122.3,
122.2, 45.7, 33.0, 28.7, 24.5, 24.3, 21.0, 20.2, 18.9, 13.8.
FT-IR (KBr disc, cmÀ1): 3032, 2955, 2866, 1609, 1597,
1545, 1432, 1370, 1193, 786, 759. Anal. Calc. for
C31H33N3NiO: C, 71.29; H, 6.37; N, 8.05. Found: C,
71.10; H, 6.82; N, 7.87%.
Phenylnickel N-butyl-6-(1-(2,6-diisopropylphenylimino)-
ethyl)picolinamide (C9): In a similar manner described for
C1, the complex C9 was obtained from the reaction of
trans-[NiCl(phenyl)(PPh3)2] and L1 as a brown powder in
1
43% yield (298 mg). H NMR (300 MHz, CDCl3): d 8.00
(m, 2H); 7.61 (d, 2H, J = 7.2); 7.21 (m, 2H), 6.82 (m,
3H) 6.59 (m, 3H), 2.64 (t, 2H); 2.20 (s, 6H); 1.88 (s, 3H);

M. Shen et al. / Journal of Organometallic Chemistry 693 (2008) 1683–1695
1693
4.5. Procedure for Kumada–Corriu reaction
of large excess of ethanol. Poly(methyl methacrylate)
(PMMA) was washed with Methanol and dried in vacuum
at room temperature for 24 h. MMA conversion was
approximately determined from the amount of PMMA
obtained.
A typical procedure (entry 4 in Table 5): A Schlenk tube
was charged with C9 (4.6 mg, 0.01 mmol), toluene (1.5 ml)
and bromobenzene (106 ll, 1.0 mmol) in an N2 atmo-
sphere. A solution of p-MeC6H4MgBr in THF (1.5 mmol,
ca. 1 M in THF) was dropwise added to the above stirring
solution at room temperature. Stirring was continued at
room temperature for 24 h. The reaction was quenched
by addition of water (6 ml). The mixture was extracted with
Et2O (3 Â 5 ml) and examined by GC/FID.
4.7. X-ray crystallographic studies
Single-crystal X-ray diffraction measurements on L1,
C2, C3 and C7 were performed by using a Rigaku R-AXIS
Rapid IP diffractometer with graphite-monochromated Mo
˚
Ka radiation (k = 0.71073 A) at 296(2) K. Cell parameters
4.6. Procedure for methyl methacrylate polymerization
were obtained by global refinement of the positions of all
collected reflections. Intensities were corrected for Lorentz
and polarization effects and empirical absorption. The
structures were solved by direct methods and refined by
full-matrix least squares on F2. All non-hydrogen atoms
were refined anisotropically. All hydrogen atoms were
placed in calculated positions. Structure solution and
refinement were performed by using the SHELXL-97 package
[23]. Crystal data and processing parameters for L1, C2, C3
and C7 are summarized in Table 7.
All procedures for polymerization were carried out
under purified N2 atmosphere. Ethyl-2-bromoisobutyrate
was added to a mixture of complex and degassed MMA
(2.0 ml, 19 mmol) in toluene (5 ml). After the mixture stood
at a definite reaction temperature for 24 h, HCl/methanol
(10%, 0.5 ml) was added to decompose the catalyst, and
THF (5 ml) was added to dissolve the resulting polymers,
which were precipitated as a white wadding by the addition
Table 7
Crystal data and refinement details for L1, C2, C3 and C7
L1
C2
C3
C7
Empirical formula
Formula weight
Crystal color
C
323.43
Yellow
20H25N3O
C32H35N3NiO
536.34
Brown
C34H39N3NiO
564.39
Brown
C74H74N6Ni2O2
1196.81
Brown
Temperature (K)
Wavelength (A)
Crystal system
Space group
293(2)
293(2)
0.71073
Monoclinic
P21/n
293(2)
0.71073
Monoclinic
P21/c
293(2)
0.71073
Monoclinic
P21/c
˚
0.71073
Monoclinic
P21/n
˚
a (A)
11.9976(4)
19.0143(7)
9.2871(4)
109.265(3)
1999.99(2)
4
1.074
0.067
696
8.8717(5)
21.4616(1)
15.2609(9)
104.993(2)
2806.8(3)
4
1.269
0.720
1136
10.8309(3)
18.1594(5)
16.2467(5)
108.488(2)
3030.53(2)
4
1.237
0.670
1200
19.2307(6)
19.2721(6)
19.0119(6)
117.854(2)
6229.8(3)
4
1.276
0.656
2528
˚
b (A)
˚
c (A)
b (°)
Volume (A )
3
˚
Z
Dcalc (Mg mÀ3
l (mmÀ1
F(000)
)
)
Crystal size (mm)
h Range (°)
0.29 Â 0.08 Â 0.07
0.35 Â 0.2 Â 0.15
0.32 Â 0.23 Â 0.13
0.35 Â 0.25 Â 0.18
1.80–28.34
1.68–28.34
1.73–28.32
2.11–28.28
Limiting indices
À15 6 h 6 15
À22 6 k 6 25
À12 6 k 6 12
À9 6 h 6 11
À28 6 k6 28
À20 6 l 6 19
À 14 6 h 6 14
À 24 6 k 6 24
À 21 6 l 6 21
À25 6 h 6 23
À25 6 k 6 22
À18 6 l 6 25
Number of reflections collected
Number of unique reflections [Rint
Completeness to h (%)
Absorption correction
Data/restraints/parameters
Goodness-of-fit on F2
18423
21039
32453
50181
]
4950 [0.0573]
99.2 (h = 28.34°)
Empirical
4950/0/210
0.875
6907 [0.0468]
98.7 (h = 28.34°)
Empirical
6907/0/316
1.040
7528 [0.0695]
99.7 (h = 28.32°)
Empirical
7528/1/342
0.825
15383 [0.1097]
99.4 (h = 28.28°)
Empirical
15383/0/757
1.032
Final R indices [I > 2r(I)]
R1 = 0.0770
R1 = 0.0850
R1 = 0.0532
R1 = 0.0821
wR2 = 0.2648
wR2 = 0.2234
wR2 = 0.1373
wR2 = 0.1223
R indices (all data)
R1 = 0.1935
R1 = 0.1338
R1 = 0.1646
R1 = 0.1964
wR2 = 0.3300
wR2 = 0.2507
wR2 = 0.1610
wR2 = 0.1575
À3
˚
Largest difference in peak and hole (e A
)
0.311, À0.216
1.224, À1.424
0.494, À0.390
0.246, À0.276

1694
M. Shen et al. / Journal of Organometallic Chemistry 693 (2008) 1683–1695
[9] (a) W. Keim, F.H. Kowaldt, R. Goddard, C. Kruger, Angew. Chem.
¨
Acknowledgements
Int. Ed. Engl. 17 (1978) 466–467;
(b) W. Keim, A. Behr, B. Limba¨cker, C. Kruger, Angew. Chem. Int.
¨
Ed. Engl. 22 (1983) 503.
This work was supported by NSFC No. 20674089 and
MOST No. 2006AA03Z553. We are grateful to Prof. Rich-
ard D. Adams and Mr. Saliu Alao Amolegbe for the Eng-
lish corrections.
[10] (a) C. Wang, S. Friedrich, T.R. Younkin, R.T. Li, R.H. Grubbs,
D.A. Bansleben, M.W. Day, Organometallics 17 (1998) 3149–
3151;
(b) T.R. Younkin, E.F. Connor, J.I. Henderson, S.K. Friedrich,
R.H. Grubbs, D.A. Bansleben, Science 287 (2000) 460–462.
[11] (a) W.-H. Sun, S. Jie, S. Zhang, W. Zhang, Y. Song, H. Ma,
Organometallics 25 (2006) 666–677;
Appendix A. Supplementary material
CCDC 671289, 671290, 671291, 671292 contain the sup-
plementary crystallographic data for compounds L1, C2,
C3, C7. These data can be obtained free of charge from
The Cambridge Crystallographic Data Centre via www.
ccdc.cam.ac.uk/data_request/cif. Supplementary data
associated with this article can be found, in the online ver-
sion, at doi:10.1016/j.jorganchem.2008.01.004.
(b) S. Jie, S. Zhang, K. Wedeking, W. Zhang, H. Ma, X. Lu, Y.
Deng, W.-H. Sun, C. R. Chim. 9 (2006) 1500–1509;
(c) S. Jie, S. Zhang, W.-H. Sun, X. Kuang, T. Liu, J. Guo, J. Mol.
Catal. A: Chem. 269 (2007) 85–96;
(d) S. Zhang, S. Jie, Q. Shi, W.-H. Sun, J. Guo, J. Mol. Catal. A:
Chem. 276 (2007) 174–183;
(e) P. Hao, S. Zhang, W.-H. Sun, Q. Shi, S. Adewuyi, X. Lu, P. Li,
Organometallics 26 (2007) 2439–2446;
(f) W.-H. Sun, P. Hao, S. Zhang, Q. Shi, W. Zuo, X. Tang,
Organometallics 26 (2007) 2720–2734;
References
(g) W.-H. Sun, P. Hao, G. Li, S. Zhang, W. Wang, J. Yi, M. Asma,
N. Tang, J. Organomet. Chem. 692 (2007) 4506–4518;
(h) S. Adewuyi, G. Li, S. Zhang, W. Wang, P. Hao, W.-H. Sun, N.
Tang, J. Yi, J. Organomet. Chem. 692 (2007) 3532–3541;
(i) M. Zhang, S. Zhang, P. Hao, S. Jie, W.-H. Sun, P. Li, X. Lu,
Euro. J. Inorg. Chem. 24 (2007) 3816–3826.
[1] (a) S.D. Ittel, L.K. Johnson, M. Brookhart, Chem. Rev. 100 (2000)
1169–1203;
(b) V.C. Gibson, S.K. Spitzmesser, Chem. Rev. 103 (2003) 283–315;
(c) F. Speiser, P. Braunstein, L. Saussine, Acc. Chem. Res. 38 (2005)
784–793;
(d) W. Zhang, W. Zhang, W.-H. Sun, Prog. Chem. 17 (2005) 310–
319;
(e) S. Jie, S. Zhang, W.-H. Sun, Petrochem. Tech. (Shiyou Huagong)
35 (2006) 295–300;
(f) W.-H. Sun, D. Zhang, S. Zhang, S. Jie, J. Hou, Kinet. Catal. 47
(2006) 278–283;
[12] W.-H. Sun, X. Tang, T. Gao, B. Wu, W. Zhang, H. Ma, Organo-
metallics 23 (2004) 5037–5047.
[13] (a) W. Zhang, W.-H. Sun, B. Wu, S. Zhang, H. Ma, Y. Li, J. Chen,
P. Hao, J. Organomet. Chem. 691 (2006) 4759–4767;
(b) W. Chen, C. Xi, K. Yang, Appl. Organometal. Chem. 21 (2007)
641–644.
[14] W.-H. Sun, W. Zhang, T. Gao, X. Tang, L. Chen, L. Yan, X. Jin, J.
Organomet. Chem. 689 (2004) 917–929.
[15] (a) B. Cornils, W.A. Herrmann (Eds.), Applied Homogeneous
Catalysis with Organometallic Compounds, second ed., Wiley-VCH,
Weinheim, 2002;
(g) I.P. Beletskaya, A.V. Cheprakov, Chem. Rev. 100 (2000) 3009–
3066.
[2] W. Liu, J.M. Malinoski, M. Brookhart, Organometallics 21 (2002)
2836–2838.
(b) M. Beller, C. Bolm (Eds.), Transition Metals for Organic
Synthesis, Wiley-VCH, Weinheim, 1998;
(c) F. Diederich, P.J. Stang (Eds.), Metal-catalyzed Cross-coupling
Reactions, Wiley-VCH, Weinheim, 1998;
(d) L. Brandsma, S.F. Vasilevsky, H.D. Verkruijsse, Application of
Transition Metal Catalysts in Organic Synthesis, Springer, Berlin,
1998.
[3] (a) Z. Guan, W.J. Marshall, Organometallics 21 (2002) 3580–3586;
(b) N.A. Cooley, S.M. Green, D.F. Wass, Organometallics 20 (2001)
4769–4771.
[4] (a) L.K. Johnson, C.M. Killian, M. Brookhart, J. Am. Chem. Soc.
117 (1995) 6414–6415;
(b) L.K. Johnson, S. Mecking, M. Brookhart, J. Am. Chem. Soc. 118
(1996) 267–268;
[16] Z.-X. Wang, L. Wang, Chem. Commun. 144 (2007) 2423–2425.
[17] (a) K. Tamao, M. Sumitani, J. Kumada, J. Am. Chem. Soc. 94 (1972)
4373–4374;
(b) R.J.P. Corriu, J.P. Masse, Chem. Commun. (1972) 144.
[18] (a) L. Pu, Chem. Rev. 98 (1998) 2405;
(c) C.M. Killian, D.J. Tempel, L.K. Johnson, M. Brookhart, J. Am.
Chem. Soc. 118 (1996) 11664–11665.
[5] (a) Q.-Z. Yang, A. Kermagoret, M. Agostinho, O. Siri, P. Braunstein,
Organometallics 25 (2006) 5518–5527;
(b) X. Tang, W.-H. Sun, T. Gao, J. Hou, J. Chen, W. Chen, J.
Organomet.Chem. 690 (2005) 1570–1580.
[6] F. Speiser, P. Braunstein, L. Saussine, J. Chem. Soc., Dalton Trans.
(2004) 1539–1545.
(b) E.-I. Negishi, F. Liu, in: F. Diederich, P.J. Stang (Eds.), Metal-
catalyzed Cross-coupling Reactions, Wiley-VCH, Weinheim, 1998, p.
p. 1.
[19] (a) S.K. Schneider, C.F. Rentzsch, A. Kruger, H.G. Raubenheimer,
W.A. Herrmann, J. Mol. Catal. A: Chem. 265 (2007) 50–58;
(b) L.-C. Liang, P.-S. Chien, J.-M. Lin, M.-H. Huang, Y.-L. Huang,
J.-H. Liao, Organometallics 25 (2006) 1399–1411.
[20] (a) J.-S. Wang, K. Matyjaszewski, J. Am. Chem. Soc. 117 (1995)
5614–5615;
[7] J. Hou, W.-H. Sun, S. Zhang, H. Ma, Y. Deng, X. Lu, Organome-
tallics 25 (2006) 236–244.
[8] (a) L. Wang, W.-H. Sun, L. Han, H. Yang, Y. Hu, X. Jin, J.
Organomet. Chem. 658 (2002) 62–70;
(b) F.A. Kunrath, R.F. Souza, O.L. Casagrande Jr., N.R. Brooks,
V.G. Yzz Jr., Organometallics 22 (2003) 4739–4743;
(c) N. Ajellal, M.C.A. Kuhn, A.D.A. Boff, M. Ho¨rner, C.M. Thomas,
J.-F. Carpentier, O.L. Casagrande Jr., Organometallics 25 (2006)
1213–1216;
(d) W.-H. Sun, S. Zhang, S. Jie, W. Zhang, Y. Li, H. Ma, J. Chen,
K. Wedeking, R. Fro¨hlich, J. Organomet. Chem. 691 (2006) 4196–
4203;
(b) Y. Shen, S. Zhu, F. Zeng, R.H. Pelton, Macromolecules 33
(2000) 5427–5431;
(c) S. Zhu, D. Yan, Macromolecules 33 (2000) 8233–8238;
(d) T. Ando, M. Kamigaito, M. Sawamoto, Macromolecules 30
(1997) 4507–4510;
(e) H. Uegaki, Y. Kotani, M. Kamigaito, M. Sawamoto, Macromol-
ecules 30 (1997) 2249–2253;
(e) S. Al-Benna, M.J. Sarsfield, M. Thornton-Pett, D.L. Ormsby,
`
(f) H. Uegaki, Y. Kotani, M. Kamigaito, M. Sawamoto, Macromol-
ecules 31 (1998) 6756–6761;
P.J. Maddox, P. Bres, M. Bochmann, J. Chem. Soc., Dalton Trans.
(2000) 4247–4257.

M. Shen et al. / Journal of Organometallic Chemistry 693 (2008) 1683–1695
1695
´
(g) G. Moineau, M. Minet, Ph. Dubois, Ph. Teyssie, T. Senninger,
R. Jeeroome, Macromolecules 32 (1999) 27–35;
[22] M. Hidai, T. Kashiwagi, T. Ikeuchi, Y. Uchida, J. Organomet.
Chem. 30 (1971) 279–282.
´
´ ˆ
(h) Ph. Lecomte, I. Drapier, Ph. Dubois, Ph. Teyssie, R. Jerome,
Macromolecules 30 (1997) 7631–7633.
[23] G.M. Sheldrick, SHELXTL-97, Program for the Refinement of Crystal
Structures, University of Gottingen, Germany, 1997.
[21] J.V. Soolingen, H.D. Verkruijsse, M.A. Keegstra, L. Brandsma,
Synth. Commun. 20 (1999) 3153–3156.