Vinyl polymerization of norbornene on nickel complexes with bis(imino)pyridine ligands containing electron-withdrawing groups

Article abstract of DOI:10.1021/om201213v

A series of novel bis(imino)pyridine nickel(II) dichloride complexes, with the bis(imino)pyridine ligands containing electron-withdrawing groups (F, Cl, Br, CF₃), have been prepared and characterized by elemental analysis and NMR spectroscopy. All complexes exhibit paramagnetically shifted ¹H NMR spectra, indicative of the high-spin (S = 1) state of the d⁸ nickel(II) central atom. These complexes have been found to be highly active catalysts of vinyl-type norbornene polymerization upon activation with MAO, displaying activities up to 1.16 × 10⁷ g of PNB (mol of cat.)^-1 h^-1 (the highest ever reported for norbornene polymerizations on bis(imino)pyridine nickel complexes) and yielding high-molecular-weight polynorbornene (M_w up to 4.5 × 10 ⁶). X-ray structures for some of the nickel complexes are reported.

Full text of DOI:10.1021/om201213v

Article
pubs.acs.org/Organometallics
Vinyl Polymerization of Norbornene on Nickel Complexes with
Bis(imino)pyridine Ligands Containing Electron-Withdrawing Groups
Artem A. Antonov,† Nina V. Semikolenova,‡ Vladimir A. Zakharov,‡ Wenjuan Zhang,§ Youhong Wang,§
Wen-Hua Sun,§ Evgenii P. Talsi,‡ and Konstantin P. Bryliakov*,‡
†Novosibirsk State University, Ul. Pirogova 2, Novosibirsk 630090, Russian Federation
‡Boreskov Institute of Catalysis, Pr. Lavrentieva 5, Novosibirsk 630090, Russian Federation
§Key Laboratory of Engineering Plastics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, People's Republic of
China
S
* Supporting Information
ABSTRACT: A series of novel bis(imino)pyridine nickel(II)
dichloride complexes, with the bis(imino)pyridine ligands containing
electron-withdrawing groups (F, Cl, Br, CF3), have been prepared and
characterized by elemental analysis and NMR spectroscopy. All
complexes exhibit paramagnetically shifted 1H NMR spectra, indicative
of the high-spin (S = 1) state of the d8 nickel(II) central atom. These
complexes have been found to be highly active catalysts of vinyl-type
norbornene polymerization upon activation with MAO, displaying
activities up to 1.16 × 107 g of PNB (mol of cat.)−1 h−1 (the highest
ever reported for norbornene polymerizations on bis(imino)pyridine
nickel complexes) and yielding high-molecular-weight polynorbornene
(Mw up to 4.5 × 106). X-ray structures for some of the nickel complexes are reported.
steric and electronic properties by the introduction of
substituents into the phenyl rings of the bis(imino)pyridyl
ligand. In this work, the catalytic activity of nickel bis(imino)-
pyridine complexes in norbornene polymerization has been
investigated. In particular, we have aimed at examining the
effect of electron-withdrawing groups (EWGs) in the aryl rings
on the catalytic activity (introduction of EWGs has been
reported to increase the activity of iron and cobalt bis(imino)-
pyridine catalysts for ethylene oligo- and polymerization36−42).
To this end, we have prepared 12 bis(imino)pyridine nickel
dichloride complexes, 11 of them containing electron-with-
drawing groups, and compared their activities toward
norbornene upon activation with MAO. All complexes
appeared to be highly active catalysts of vinyl norbornene
polymerization, displaying activities up to 1.16 × 107 g of PNB
(mol of cat.)−1 h−1 and yielding high-molecular-weight
polynorbornene (Mw up to 4.5 × 106). X-ray structures for
some of the catalysts are reported.
INTRODUCTION
■
The area of catalytic polymerization of cyclic olefins such as
norbornene has expanded significantly within the last two
decades.1−10 Vinyl (addition) type polymerization of norbor-
nene (first reported by Sartori and co-workers)11,12 leaves the
bicyclic structure intact, thus yielding rigid and thermally stable
polynorbornene. So far, there have been numerous reports on
vinyl-type norbornene polymerization, nickel-based complexes
emerging as active and flexible single-site catalysts for
polymerizations of this type.3−10,13
In the last two decades, major breakthroughs in post-
metallocene-catalyzed olefin polymerizations were made by
Brookhart with co-workers, who reported14 nickel(II) bis-
(imine) catalysts for ethylene and α-olefin polymerization.
Three years later Brookhart15 and Gibson and co-workers16,17
found that iron and cobalt bis(imino)pyridine complexes are
highly active in ethylene polymerization to linear polyethylene.
Despite the great popularity of Fe- and Co-based bis(imino)-
pyridine catalysts (see reviews18−25), they have been applied in
norbornene polymerization with very limited success and
exhibited rather moderate activities (in most cases not
exceeding 102−104 g of PNB (mol of cat.)−1 h−1).9,10
Surprisingly, there have been just a few accounts reporting
nickel bis(imino)pyridine catalyzed polymerization of norbor-
nene upon activation with MAO.26−28 We have had a
longstanding interest in bis(imino)pyridine-based catalysts of
olefin polymerization,29−35 due to the remarkable simplicity of
ligand syntheses and rich opportunities for fine-tuning of their
RESULTS AND DISCUSSION
■
Synthesis of Bis(imino)pyridine Ligands and of
Nickel(II) Complexes. While Schiff condensation of diac-
etylpyridine with anilines containing electron-donating groups
proceeds smoothly in ethanol or methanol using carboxylic
acids (such as acetic or formic acid) as catalysts, as reported in
Received: December 6, 2011
Published: January 23, 2012
© 2012 American Chemical Society
1143
dx.doi.org/10.1021/om201213v | Organometallics 2012, 31, 1143−1149

Organometallics
Article
the milestone accounts of Brookhart15 and Gibson,16,17
condensation with anilines containing electron-withdrawing
substituents may present some difficulties and requires the use
of different reaction conditions. Specifically, the use of stronger
acids (either Brønsted or Lewis), higher temperatures, and
more careful moisture removal is needed. The general method
for the preparation of the bis(imino)pyridine ligands and of the
nickel(II) dichloride complexes derived thereof is presented in
Scheme 1.43
linearity in a wider range (220−330 K). These deviations could
be due to some conformational dynamics which unfreezes
around 250−280 K for most of the complexes studied.
Single crystals of complexes 5 and 6 have been obtained (see
the Experimental Section) and measured by single-crystal X-ray
diffraction. Complex 5 cocrystallized with two water molecules
per nickel; one of those molecules entered the inner
coordination sphere of the central atom, forming an octahedral
coordination environment (Figure 1a). In complex 6, nickel is
five-coordinate, thus adopting a distorted-square-pyramidal
geometry at the metal center. Complex 6 has approximate Cs
symmetry; both CF3 groups in 6 are syn oriented, pointing
away from the apical ligand, in a way similar to that previously
reported for the cobalt counterpart of 6.39 The bond lengths of
Ni−Cl in 5 (2.3247(17), 2.4389(19) Å) are much longer that
those in 6 (2.2645(14), 2.2870(14) Å), which may be due to
the stronger electron-withdrawing effect of the −CF3 group,
while the bond lengths of Ni−N are very close, at 2.011(4)−
2.153(4) Å in 5 and 1.994(5)−2.146(6) Å in 6. Further
structural data for 5 and 6 can be found in the Supporting
Information.
Scheme 1. Synthesis of Bis(imino)pyridine Ligands and of
a
Ni(II) Complexes
Ethylene Oligomerization and Norbornene Polymer-
ization on Bis(imino)pyridine Nickel Complexes. First of
all, ethylene reactivity of the synthesized complexes was probed
(Table 1). Four Ni complexes have been tested as catalysts of
a
Method A: p-toluenesulfonic or trifluoroacetic acid, toluene,
Table 1. Ethylene Oligomerization on Bis(imino)pyridine
Nickel Complexes
azeotropic removal of water. Method B: MAO/SiO2, toluene, 40 °C,
MS 4 Å. Method C: dry CH3CN, room temperature. Method D: dry
THF, room temperature.
a
C2H4
consumption, g
b
no.
Ni complex
co-cat.
activity
product
Common drawbacks of method A (Scheme 1) are its limited
use (mainly for anilines with one or two halogens) and the
existence of side processes leading (after prolonged distillation
of the reaction mixture) to resinification of the reactants. In
many cases, fortunately, method A could be successfully
replaced by method B, which requires milder conditions and
thus allows avoiding resinification, resulting in higher yields of
the target Schiff bases.
1
2
3
4
5
Ni-2-CF3 (6)
Ni-2-iPr (12)
MAO
MAO
1.25
1.31
1.49
1.56
2.38
1.25
1.31
1.49
1.56
2.38
butene
butene
butene
butene
butene
Ni-2,6-Cl2 (11) MAO
Ni-3,5-Cl2 (5)
Ni-3,5-Cl2 (5)
MAO
Et2AlCl
a
Reaction conditions: toluene, 50 mL; Ni complex, 2 μmol; Al/Ni =
500/1; ethylene pressure, 5 bar; temperature, 35 °C; reaction time, 1
b
h. In units of 105 g (mol of Ni)−1 h−1 bar−1.
Most of the nickel(II) complexes were prepared according to
a common method C in CH3CN (except complexes 11 and 12,
which were synthesized in either dry THF or in THF/
CH3CN). All complexes exhibited paramagnetic 1H NMR
spectra in methanol-d4 or in chloroform-d solutions, indicating
a high-spin (S = 1) state of the d8 central atom. The
experimental temperature dependences (see the Supporting
Information) of the observed paramagnetic shifts (δ vs T−1)
satisfactorily obey the Curie law44 at low temperatures (below
250−265 K) but demonstrate substantial deviations from
ethylene oligomerization upon activation with MAO (Table 1).
All of them showed fairly moderate ethylene consumption
((1.2−1.5) × 105 g (mol of cat.)−1 h−1 bar−1). Replacement of
MAO with Et2AlCl resulted in a slight increase of the activity
up to 2.4 × 105 g (mol of cat.)−1 h−1 bar−1. Butene-1 was the
only detectable45 product of this reaction, and no traces of solid
polymer were found. Such reaction behavior is similar to that
reported for bis(imino)pyridine-based and structurally related
nickel(II) complexes with N,N,N-donor ligands.46−53
Figure 1. Molecular structures of complexes 5 (a) and 6 (b), with thermal ellipsoids at the 30% probability level. Hydrogen atoms are omitted for
clarity.
1144
dx.doi.org/10.1021/om201213v | Organometallics 2012, 31, 1143−1149

Organometallics
Article
Norbornene polymerizations over bis(imino)pyridine cata-
lysts containing alkyl substituents in the aryl rings have been
reported previously.26−28 While Sacchi and co-workers reported
low polymerization activities at 50 °C ((1−5) × 103 g of PNB
(mol of Ni)−1 h−1 in toluene and up to 2 × 104 g of PNB (mol
of Ni)−1 h−1 in 1,2-dichlorobenzene),26 Chen and co-workers
found the activities to be much higher (up to 4.7 × 106 g of
PNB (mol of Ni)−1 h−1) in chlorobenzene at 30 °C.28 To probe
the effect of electron-withdrawing substituents on norbornene
polymerization activity, complexes 1−12 were tested as
catalysts, using methylaluminoxane as the activator and
chlorobenzene as the reaction solvent.54 Most of the complexes
demonstrated activities on the order of (1−2) × 106 g of PNB
(mol of Ni)−1 h−1 at 30 °C at NB/Ni ratios of 25 000/1 (Table
substituent in the aryl ring exhibited the lowest catalytic activity
(entry 9). Interestingly, while complexes with one para
electron-withdrawing substituent were highly active (entries
12 and 13), those having one ortho and one para substituent
displayed lower activities (entries 14 and 15).
A possible reason for the deactivating effect of ortho
substituents55 could be the steric effects caused by the ortho
substituents: complex 9 (Ni-3-CF3-4-F, entry 19) demonstrated
a 5 times higher activity compared to 8 (Ni-2-CF3-4-F, entry
14). Complexes with two meta substituents (entries 17 and 18)
were found to be more active than those with two ortho
substituents (entry 16). Three F substituents led to a highly
reactive catalyst (entry 20).
In contrast to the ethylene polymerization experiments, the
replacement of MAO with Et2AlCl resulted in a more than 10-
fold drop of catalytic activity (entries 21 and 22). Ni complexes
studied were found to yield high-molecular-weight polynorbor-
nene, Mw exceeding 3 × 106 g/mol (Supporting Information).
These Mw values are among the highest recently reported for
norbornene polymerization on nickel-based catalysts.6,26,56−64
The resulting polymers exhibited narrow molecular weight
distributions of 2.1−2.2 (Supporting Information), indicative of
true single-site catalysts, and NMR spectra typical for vinyl-type
polynorbornenes, with no sign of ROMP units (cf. the
Supporting Information and ref 26).
Table 2. Norbornene Polymerization on Bis(imino)pyridine
a
Nickel Complexes
T,
°C
reacn time,
min
PNB
yield, g activity
b
no.
Ni complex
NB/Ni
1
2
Ni-2-CF3 (6)
25 000
25 000
30
30
60
60
0.95
1.23
0.95
1.23
Ni-2-CF3-4-F
(8)
3
Ni-2-Cl-4-F
(3)
25 000
30
60
1.57
1.57
4
5
6
7
Ni-2,6-Cl2 (11) 25 000
30
30
30
30
60
60
60
60
1.68
1.92
1.98
2.07
1.68
1.92
1.98
2.07
Ni-3,5-Cl2 (5)
Ni-3,5-F2 (7)
25 000
25 000
25 000
CONCLUSIONS
■
Ni-2,4,6-F3
A series of new nickel complexes containing electron-
withdrawing substituents have been synthesized and charac-
terized, and their ethylene and norbornene reactivities in the
presence of MAO have been examined. These complexes have
been found to be moderately active catalysts of ethylene
oligomerization in toluene (showing ethylene consumptions up
to 2.38 × 105 g (mol of cat.)−1 h−1 bar−1) and highly active
catalysts of vinyl-type norbornene polymerization in chlor-
obenzene upon activation with MAO, displaying activities up to
1.16 × 107 g of PNB (mol of cat.)−1 h−1 (the highest ever
reported for norbornene polymerizations over bis(imino)-
pyridine nickel complexes) and yielding high-molecular-weight
polynorbornene (Mw up to 4.5 × 106). The presence of
electron-withdrawing groups is crucial for achieving high
norbornene polymerization activity: meta and para EWG's
have the highest activating impact, while the presence of ortho
substituents in most cases leads to lower activities, apparently
because of steric effects. The only exception is complex 4 (Ni-
2-F, containing one small, strongly electron-withdrawing ortho
substituent, entry 10), which is the most reactive of all
complexes studied.
(10)
8
9
Ni-3-CF3-4-F
25 000
30
60
2.21
2.21
0.68
(9)
Ni-2-iPr (12)
50 000
50 000
50 000
50 000
50 000
50 000
60
60
60
60
60
60
15
15
15
15
15
15
0.17
2.91
0.95
0.86
1.64
0.35
10 Ni-2-F (4)
11 Ni-2-CF3 (6)
12 Ni-4-Br (2)
13 Ni-4-F (1)
11.6
3.81
3.44
6.55
1.39
14 Ni-2-CF3-4-F
(8)
15 Ni-2-Cl-4-F
50 000
60
15
0.64
2.56
(3)
16 Ni-2,6-Cl2 (11) 50 000
60
60
60
60
15
15
15
15
0.97
2.76
1.17
1.82
3.88
17 Ni-3,5-Cl2 (5)
18 Ni-3,5-F2 (7)
50 000
50 000
50 000
11.1
4.67
7.30
19 Ni-3-CF3-4-F
(9)
20 Ni-2,4,6-F3
50 000
60
15
2.35
9.43
(10)
c
21 Ni-3,5-Cl2 (5)
50 000
50 000
60
60
15
15
0.15
0.21
0.61
0.86
22 Ni-2,4,6-F3
c
(10)
a
Reaction conditions: chlorobenzene, 50 mL; Ni complex, 1 μmol;
b
cocatalyst, MAO; Al/Ni = 500/1. In units of 106 g (mol of Ni)−1 h−1.
EXPERIMENTAL SECTION
c
■
Activator Et2AlCl (Al/Ni = 500).
General Experimental Details. All manipulations with air- and/
or moisture-sensitive compounds were performed under an atmos-
phere of argon using glovebox, break-seal, or standard Schlenk
techniques. Toluene was dried over molecular sieves (4 Å) and
distilled over sodium under argon. THF was stored over NaOH and
distilled over sodium under argon before use. CH3CN was stored over
molecular sieves (4 Å) under an atmosphere of argon. Chlorobenzene
was dried over P2O5 and distilled under argon. Other solvents were
used as received without further purification.
2, entries 1−8). One can see that (1) the activity increases with
an increasing number of electron-withdrawing substituents and
(2) two meta substituents have a stronger activating effect
compared to ortho substituents. The activities were found to
increase several times at 60 °C and at NB/Ni ratios of 50 000/1
(Table 2, entries 9−20). Further experimentation was
conducted at 60 °C; the reaction times were shortened to
minimize the possible effect of diffusion-caused deceleration at
high conversions on the apparent catalytic activities. The
observed reactivity trends were generally retained at that
temperature. Complex 12 with an electron-donating o-iPr
2,6-Diacetylpyridine was purchased from Acros. Substituted anilines
were purchased from Acros, Aldrich, Alfa Aesar, and Maybridge and
used as received. Anhydrous NiCl2 was prepared by heating
commercially available NiCl2·6H2O at 140 °C in vacuo for 4.5 h.
MAO/SiO2 was prepared as described.65 Norbornene (bicyclo[2.2.1]-
1145
dx.doi.org/10.1021/om201213v | Organometallics 2012, 31, 1143−1149

Organometallics
Article
hept-2-ene) was dried and distilled over sodium under an argon
atmosphere.
Saturn 724 + CCD diffractometer with graphite-monochromated Mo
Kα radiation (λ = 0.710 73 Å). Cell parameters 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. The hydrogen atoms were placed in
calculated positions. Structure solution and refinement were
performed by using the SHELX-97 package.67 Details of the X-ray
structure determinations and refinements are provided in Table S1.
Synthesis of Ligands. 2,6-Bis[1-(4-fluorophenylimino)ethyl]-
pyridine (L1). 2,6-Diacetylpyridine (0.326 g, 2 mmol), 4-fluoroaniline
(0.475 mL, 5 mmol), and trifluoroacetic acid (40 μL) in benzene (50
mL) were refluxed for 1 h with azeotropic removal of water using a
Dean−Stark trap. The mixture was cooled to room temperature, and
the solvent was removed under reduced pressure. The solid residue
was dissolved in hot methanol. After the solution was cooled to room
temperature, L1 precipitated as a yellow powder. The desired product
1H NMR spectra of 2,6-bis(imino)pyridyl ligands and of nickel(II)
complexes were recorded either on a Bruker Avance-400 MHz NMR
spectrometer (at 400.130 MHz) or on a Bruker DPX-250 MHz NMR
spectrometer (at 250.130 MHz). 1H and 13C NMR spectra of
polynorbornenes were recorded on a Bruker Avance-400 MHz NMR
spectrometer at 400.130 and 100.613 MHz, respectively, in o-
dichlorobenzene at 99 °C using 10 mm o.d. glass NMR tubes.
Methylalumoxane (MAO; commercial sample) was purchased from
Crompton as a toluene solution (total Al content 1.8 M, Al as AlMe3
∼0.5 M).
Ethylene Oligomerization Procedure. The oligomerization was
performed in a steel 1 L autoclave. The catalyst (2.0 × 10−6 mol) was
introduced into the autoclave in a vacuum-sealed glass ampule. The
reactor was evacuated at 80 °C, cooled to 20 °C, and charged with the
solution of cocatalyst (1 mmol Al) in toluene (50 mL). After the
polymerization temperature (35 °C) and ethylene pressure (5 bar)
were set, the reaction was started by breaking the ampule containing
the complex. During the oligomerization, the ethylene pressure,
stirring speed, and temperature were maintained constant. The
experimental unit was equipped with an automatic computer-
controlled system for ethylene feed and recording of the ethylene
consumption. After 1 h, the reactor was vented; 2.5 mL of the reaction
mixture was quickly pipetted and placed into the 10 mm tube and
analyzed by NMR.
Norbornene Polymerization Procedure. Method I. A 100 mL
round-bottom flask with a magnetic stirrer was evacuated, flame-
heated, cooled to room temperature, and flushed with argon. Then the
catalyst (1.0 × 10−6 mol) was introduced into the flask. The reactor
was charged with norbornene (0.025 mol, 2.35 g, or 0.050 mol, 4.7 g),
chlorobenzene (50 mL), and cocatalyst (1.0 mL of MAO solution (0.5
M Al in toluene)) in a glovebox. The flask was quickly removed from
the glovebox and placed in a water bath thermostated at the
appropriate temperature, and the mixture was magnetically stirred at
900 rpm. The reaction was terminated by injection of 22 mL of
acidified ethanol (10/1 ethanol/HCl, v/v). The precipitate of
polynorbornene was filtered off, washed with ethanol (3 × 10 mL),
and dried to constant weight under ambient temperature.
1
was obtained in 23.9% yield (0.167 g, 0.48 mmol). H NMR (400
MHz, CDCl3/CCl4): δ 8.34 (d, 2H, J = 7.8 Hz, PyHm); 7.86 (t, 1H, J
= 7.8 Hz, PyHp); 7.04 (t, 4H, ArH); 6.74 (m, 4H, ArH); 2.39 (s, 6H,
NCMe).
2,6-Bis[1-(4-bromophenylimino)ethyl]pyridine (L2). This ligand
was prepared from 2,6-diacetylpyridine (0.276 g, 1.69 mmol), 4-
bromoaniline (0.475 mL, 5 mmol), and trifluoroacetic acid (20 μL) in
benzene (65 mL) using a procedure analogous to that for L1 (reflux
time 6 h). L2 was obtained as a yellow powder in 41% yield (0.326 g,
1
0.69 mmol). H NMR (400 MHz, CDCl3/CCl4): δ 8.33 (d, 2H, J =
7.8 Hz, PyHm); 7.87 (t, 1H, J = 7.8 Hz, PyHp); 7.47 (d, 4H, J = 8.5 Hz,
ArH); 6.7 (d, 4H, J = 8.5 Hz, ArH); 2.39 (s, 6H, NCMe).
2,6-Bis[1-(2-chloro-4-fluorophenylimino)ethyl]pyridine (L3). Mo-
lecular sieves (4 Å; 2.7 g) were activated under vacuum by heating to
600 °C for 15 min. The flask was cooled to room temperature. Then
2,6-diacetylpyridine (0.326 g, 2 mmol), 2-chloro-4-fluoroaniline (0.6
mL, 5 mmol), and toluene (12 mL) were added. The solution was
degassed three times, and after the flask was heated to room
temperature, the heterogeneous catalyst MAO/SiO2 (0.2 g) was
added. The reaction mixture was stirred at 40 °C for 44 h. Molecular
sieves were filtered off and washed with CH2Cl2 (3 × 4 mL). The
combined filtrate was distilled off under vacuum. The solid residue was
triturated with methanol (10 mL), and undissolved L3 was filtered off
and dried out. L3 was obtained as a pale yellow powder in 80% yield
Method II. A stock solution of norbornene in chlorobenzene was
prepared as follows: in a glovebox, a 300 mL round-bottom flask was
charged with norbornene (150 mmol, 14.1 g), and chlorobenzene
(133.5 mL) was added.
1
(0.671 g, 1.6 mmol). H NMR (400 MHz, CCl4): δ 8.44 (d, 2H, J =
7.8 Hz, PyHm); 7.9 (t, 1H, J = 7.8 Hz, PyHp); 7.2 (dd, 2H, 3J = 8.2 Hz,
4J = 2.7 Hz, ArHm); 7.0 (td, 2H, 3J = 8.2 Hz, 4J = 2.7 Hz, ArHm′); 6.75
(m, 2H, ArHo), 2.36 (s, 6H, NCMe).
A 100 mL round-bottom flask was evacuated, flame-heated, cooled
to room temperature, and flushed with argon. The flask was charged
with the catalyst (1.0 × 10−6 mol) and the stock solution of
norbornene in chlorobenzene (50 mL). The reactor was placed in a
water bath, and the reaction was initiated by injecting 0.5 mL of MAO
solution (1.0 M Al in toluene) via syringe. The reaction was
terminated by adding 22 mL of acidified ethanol (10/1 ethanol/HCl,
v/v). The precipitate of polynorbornene was filtered off, washed with
ethanol (3 × 10 mL), and dried to constant weight under ambient
temperature.
Polymer MW and MWD Measurements. Polymer MW and
MWD measurements were performed using a Waters 150C instru-
ment. Run conditions were as follows: temperature, 140 °C; solvent,
1,2,4-trichlorobenzene (TCB). Four mixed-bed PL-gel Olexis columns
were used at a flow rate of 1 cm3/min. Conventional calibration was
made using narrow polystyrene and polyethylene standards. The
Mark−Houwink parameters K = 9.872 × 10−5 dL/g and a = 0.6793 of
polynorbornene (PNB) in 1,2,4-trichlorobenzene (TCB) were used as
reported.66
2,6-Bis[1-(2-fluorophenylimino)ethyl]pyridine (L4). This ligand
was prepared according to a procedure similar to that for L3, using
2,6-diacetylpyridine (0.326 g, 2 mmol), 2-fluoroaniline (0.485 mL, 5
mmol), 4 Å molecular sieves (2.7 g), and MAO/SiO2 (0.165 g) and
stirring the mixture for 3 days at 40 °C. L4 was obtained as a light
green powder in 61% yield (0.426 g, 1.22 mmol). 1H NMR (400 MHz,
CCl4): δ 8.43 (d, 2H, J = 7.8 Hz, PyHm); 7.9 (t, 1H, J = 7.8 Hz, PyHp);
7.13−7.0 (m, 6H, ArH); 6.86 (t, 2H, J = 8.2 Hz, ArH); 2.4 (s, 6H,
NCMe).
2,6-Bis[1-(3,5-dichlorophenylimino)ethyl]pyridine (L5). This li-
gand was prepared according to a procedure similar to that for L3,
using 2,6-diacetylpyridine (0.326 g, 2 mmol), 3,5-dichloroaniline
(0.828 g, 5 mmol), 4 Å molecular sieves (2.7 g), and MAO/SiO2
(0.165 g) and stirring the mixture for 2 days at 40 °C. Workup as
above for L3 gave L5 as a pale yellow powder in 78.5% yield (0.708 g,
1
1.57 mmol). H NMR (400 MHz, CCl4): δ 8.3 (d, 2H, J = 7.8 Hz,
X-ray Measurements. Crystals suitable for X-ray structural
determination were obtained as follows: monocrystals of 5 were
grown from acetonitrile/dichloromethane (2/1) solution in a freezer;
monocrystals of 6 were grown upon slow diffusion of Et2O into a
solution of 6 in dichloromethane at 0 °C. A single-crystal X-ray
diffraction study for 5 was carried out on a Rigaku MM007-HF Saturn
724 + CCD diffractometer with confocal mirror monochromated Mo
Kα radiation (λ = 0.710 73 Å); that of 6 was carried out on a Rigaku
PyHm); 7.9 (t, 1H, J = 7.8 Hz, PyHp); 7.11 (s, 2H, ArHp); 6.7 (s, 4H,
ArHo); 2.43 (s, 6H, NCMe).
2,6-Bis[1-(2-trifluoromethylphenylimino)ethyl]pyridine (L6). This
ligand was prepared according to a procedure similar to that for L3,
using 2,6-diacetylpyridine (0.326 g, 2 mmol), 2-trifluoromethylaniline
(0.62 mL, 5 mmol), molecular sieves 4 Å (3 g), and MAO/SiO2 (0.16
g) and stirring the mixture for 2 days at 40 °C. Workup as above for
L3 gave L6 as white crystals in 38.9% yield (0.262 g, 0.58 mmol) by
1146
dx.doi.org/10.1021/om201213v | Organometallics 2012, 31, 1143−1149

Organometallics
Article
1
recrystallization from MeOH. H NMR (400 MHz, CCl4): δ 8.38 (d,
2H, J = 7.8 Hz, PyHm), 7.93 (t, 1H, J = 7.8 Hz, PyHp), 7.67 (d, 2H, J =
7.8 Hz, ArHm), 7.49 (t, 2H, J = 7.8 Hz, ArH′m), 7.16 (t, 2H, J = 7.8 Hz,
ArHp), 6.73 (d, 2H, J = 7.8 Hz, ArHo), 2.36 (s, 6H, NCMe).
2,6-Bis[1-(3,5-difluorophenylimino)ethyl]pyridine (L7). This ligand
was prepared according to a procedure similar to that for L3, using 2,6-
diacetylpyridine (0.241 g, 1.48 mmol), 3,5-difluoroaniline (0.477 g, 3.7
mmol), 4 Å molecular sieves (2.7 g), and MAO/SiO2 (0.15 g) and
stirring the mixture for 3 days at 40 °C. Workup as above for L3 gave
L7 in 69% yield (0.393 g, 1.02 mmol). 1H NMR (400 MHz, CCl4): δ
8.33 (d, 2H, J = 7.8 Hz, PyHm); 7.89 (t, 1H, J = 7.8 Hz, PyHp); 6.54
(tt, 2H, 3J = 8.9 Hz, 4J = 2 Hz, ArHp); 6.31 (dd, 4H, 3J = 7.8 Hz, 4J = 2
Hz, ArHo); 2.42 (s, 6H, NCMe).
[2,6-bis[1-(4-bromophenylimino)ethyl]pyridine]NiCl2 (2). L2
(103.6 mg, 0.22 mmol) and NiCl2 (28.5 mg, 0.22 mmol) were
dissolved in CH3CN (10 mL) and stirred for 20 h. The product
precipitated from the solution as a reddish brown powder. 2 was
filtered off, washed with Et2O (3 × 2 mL), and vacuum-dried at room
temperature. The desired product was obtained in 47.5% yield (62.8
mg). 1H NMR (400 MHz, methanol-d4, 60 °C): δ 68.72 (s, 2H, Δν1/2
= 398.2 Hz, PyHm); 15.57 (s, 1H, Δν1/2 = 59.6 Hz, PyHp); 12.57 (s,
4H, Δν1/2 = 44.2 Hz, ArHm), −2.85 (s, 6H, Δν1/2 = 126.3 Hz, N
CMe); −7.18 (s, 4H, Δν1/2 = 518.0 Hz, ArHo). Anal. Calcd for
C21H17Cl2Br2N3Ni: C, 41.98; H, 2.85; N, 6.99. Found: C, 41.37; H,
2.78; N, 6.70.
[2,6-bis[1-(2-chloro-4-fluorophenylimino)ethyl]pyridine]NiCl2 (3).
L3 (92 mg, 0.22 mmol) and NiCl2 (28.5 mg, 0.22 mmol) were
dissolved in CH3CN (10 mL) and stirred for 4 h. Using a procedure
analogous to that for 1, 3 was obtained as brown crystals in 64.2%
yield (77.3 mg). 1H NMR (400 MHz, CDCl3, 60 °C): δ 70.17 (s, 2H,
Δν1/2 = 96.2 Hz, PyHm); 18.45 (s, 1H, Δν1/2 = 29.0 Hz, PyHp); 16.48
(s, 2H, Δν1/2 = 22.9 Hz, ArHm); 14.05 (s, 2H, Δν1/2 = 21.4 Hz,
ArH′m); 2.33 (s, 2H, Δν1/2 = 68.7 Hz, ArHo); 1.41 (s, 6H, Δν1/2 = 33.6
Hz, NCMe). Anal. Calcd for C21H15Cl4F2N3Ni: C, 46.04; H, 2.76;
N, 7.67. Found: C, 45.80; H, 2.77; N, 7.15.
[2,6-bis[1-(2-fluorophenylimino)ethyl]pyridine]NiCl2 (4). L4 (76.8
mg, 0.22 mmol) and NiCl2 (28.5 mg, 0.22 mmol) were dissolved in
CH3CN (10 mL) and stirred for 20 h. Using a procedure analogous to
that for 2, 4 was obtained as a light brown powder in 70.7% yield (74.4
mg). 1H NMR (400 MHz, methanol-d4, 60 °C): δ 67.74 (s, 2H, Δν1/2
= 286.9 Hz, PyHm); 15.61 (s, 1H, Δν1/2 = 48.8 Hz, PyHp); 12.74 (s,
2H, Δν1/2 = 36.7 Hz, ArHm); 10.97 (s, 2H, Δν1/2 = 48.8 Hz, ArH′m);
−1.7 (s, 2H, Δν1/2 = 282.8 Hz, ArHo); −5.46 (s, 2H, Δν1/2 = 47.3 Hz,
ArHp). The signal of NCMe was not observed because of
overlapping with signal of the solvent or wide broadening of this
signal. Anal. Calcd for C21H17Cl2F2N3Ni: C, 52.66; H, 3.58; N, 8.77.
Found: C, 52.50; H, 3.47; N, 8.55.
[2,6-bis[1-(3,5-dichlorophenylimino)ethyl]pyridine]NiCl2 (5). L5
(99.2 mg, 0.22 mmol) and NiCl2 (28.5 mg, 0.22 mmol) were
dissolved in CH3CN (9 mL) and stirred for 21 h. Using a procedure
analogous to that for 2, 5 was obtained as a yellow powder in 55.8%
yield (71.2 mg). 1H NMR (400 MHz, methanol-d4, 60 °C): δ 68.36 (s,
2H, Δν1/2 = 303.7 Hz, PyHm); 15.89 (s, 1H, Δν1/2 = 102.3 Hz, PyHp);
−2.18 (s, 6H, Δν1/2 = 150 Hz, NCMe); −5.68 (s, 2H, Δν1/2 = 59.5
Hz, ArHp), −7.16 (s, 4H, Δν1/2= 450.6 Hz, ArHo). Anal. Calcd for
C21H15Cl6N3Ni: C, 43.43; H, 2.60; N, 7.24. Found: C, 42.58; H, 2.79;
N, 7.83.
2,6-Bis[1-(2-trifluoromethyl-4-fluorophenylimino)ethyl]pyridine
(L8). This ligand was prepared according to a procedure similar to that
for L3, using 2,6-diacetylpyridine (0.245 g, 1.5 mmol), 2-
trifluoromethyl-4-fluoroaniline (0.49 mL, 3.75 mmol), 4 Å molecular
sieves (2.7 g), and MAO/SiO2 (0.18 g) and stirring the mixture for 2
days at 40 °C. Workup as above for L3 gave L8 as a white powder in
70% yield (0.51 g, 1.05 mmol). 1H NMR (400 MHz, CCl4): δ 8.37 (d,
2H, J = 7.8 Hz, PyHm), 7.93 (t, 1H, J = 7.8 Hz PyHp), 7.41 (dd, 2H, 3J
4
3
4
= 8.5 Hz, J = 2.7 Hz, ArHm), 7.23 (td, 2H, J = 8.5 Hz, J = 2.7 Hz,
ArHm′), 6.72 (m, 2H, ArHo), 2.36 (s, 6H, NCMe).
2,6-Bis[1-(3-trifluoromethyl-4-fluorophenylimino)ethyl]pyridine
(L9). This ligand was prepared according to a procedure similar to that
for L3, using 2,6-diacetylpyridine (0.245 g, 1.5 mmol), 3-
trifluoromethyl-4-fluoroaniline (0.485 mL, 3.75 mmol), 4 Å molecular
sieves (2.7 g), and MAO/SiO2 (0.17 g) and stirring the mixture for 3
days at 40 °C. Using a workup as above for L3, L9 was obtained in
70% yield (0.534 g, 1.1 mmol). 1H NMR (400 MHz, CCl4): δ 8.35 (d,
2H, J = 7.8 Hz, PyHm), 7.91 (t, 1H, J = 7.8 Hz, PyHp), 7.21 (t, 2H, J =
9.2 Hz, ArHm), 7.06 (dd, 2H, 3J = 6.2 Hz, 4J = 2.7 Hz, ArHo), 6.95 (m,
2H, ArH′o), 2.42 (s, 6H, NCMe).
2,6-Bis[1-(2,4,6-trifluorophenylimino)ethyl]pyridine (L10). This
ligand was prepared according to a procedure similar to that for L3,
using 2,6-diacetylpyridine (0.326 g, 2 mmol), 2,4,6-trifluoroaniline
(0.735 g, 5 mmol), 4 Å molecular sieves (2.7 g), and MAO/SiO2 (0.15
g) and stirring the mixture for 3 days at 40 °C. Workup as above for
1
L3 gave L10 in 57.9% yield (0.488 g, 1.16 mmol). H NMR (250
MHz, CCl4): δ 8.46 (d, 2H, J = 7.8 Hz, PyHm); 7.92 (t, 1H, J = 7.8 Hz,
PyHp); 6.74 (t, 4H, J = 8.2 Hz, ArHm); 2.43 (s, 6H, NCMe).
2,6-Bis[1-(2,6-dichlorophenylimino)ethyl]pyridine (L11). 2,6-Diac-
etylpyridine (0.245 g, 1.5 mmol), 2,6-dichloroaniline (0.729 g, 4.5
mmol), and p-toluenesulfonic acid (10 mg) in toluene (100 mL) were
refluxed for about 18 h with azeotropic removal of water using a
Dean−Stark trap. The mixture was cooled to room temperature, and
the solvent was removed under reduced pressure. The residue was
separated on the chromatographic column with silica gel using
hexane/EtOAc as eluent. The desired product was obtained in 30.7%
yield (0.21 g, 0.46 mmol). 1H NMR (400 MHz, CDCl3/CCl4): δ 8.54
(d, 2H, J = 7.9 Hz, PyHm); 7.96 (t, 1H, J = 7.9 Hz, PyHp); 7.33 (d, 4H,
J = 8.2 Hz, ArHm); 6.97 (t, 2H, J = 8.2 Hz, ArHp); 2.36 (s, 6H, N
CMe).
[2,6-bis[1-(2-trifluoromethylphenylimino)ethyl]pyridine]NiCl2 (6).
L6 (98.8 mg, 0.22 mmol) and NiCl2 (28.5 mg, 0.22 mmol) were
dissolved in CH3CN (9 mL) and stirred for 69 h. The solvent was
removed under reduced pressure, and a dark red oily residue was
recrystallized from CH2Cl2 (18 mL). The product precipitated as dark
red crystals, which were washed with Et2O (3 × 3 mL) and dried
under vacuum. 6 was obtained in 76% yield (96.8 mg). 1H NMR (400
MHz, methanol-d4, 60 °C): δ 64.7 (s, 2H, Δν1/2 = 230.4 Hz, PyHm);
16.34 (s, 1H, Δν1/2 = 98.0 Hz, PyHp); 11.96 (s, 2H, Δν1/2 = 70.2 Hz,
ArHm); 11.47 (s, 2H, Δν1/2 = 96.1 Hz, ArH′m); −5.3 (s, 2H, Δν1/2
=
2,6-Bis[1-(2-isopropylphenylimino)ethyl]pyridine (L12). This li-
gand was prepared as described previously.68
65.0 Hz, ArHp); −9.2 (s, 2H, Δν1/2≈1.1 kHz, ArHo). The signal of
NCMe was not observed because of overlapping with signal of the
solvent or wide broadening of this signal. The desired product
crystallized as 6·CH2Cl2. Anal. Calcd for C25H22Cl4F6N3Ni: C, 44.22;
H, 3.27; N, 6.19. Found: C, 43.74; H, 2.82; N, 6.18.
Synthesis of Nickel(II) Complexes. [2,6-bis[1-(4-
fluorophenylimino)ethyl]pyridine]NiCl2 (1). L1 (76.8 mg, 0.22
mmol) and NiCl2 (28.5 mg, 0.22 mmol) were dissolved in CH3CN
(12 mL) with rapid stirring. The reaction mixture was stirred for 3
days, and then the reaction volume was reduced to about 1 mL by
removing the solvent in vacuo. The product precipitated from the
solution as reddish brown crystals. 1 was filtered off, washed with Et2O
(3 × 2 mL), and vacuum-dried at room temperature. The desired
[2,6-bis[1-(3,5-difluorophenylimino)ethyl]pyridine]NiCl2 (7). L7
(84.8 mg, 0.22 mmol) and NiCl2 (28.5 mg, 0.22 mmol) were
dissolved in CH3CN (9 mL) and stirred for 66 h. Using a procedure
analogous to that for 1, 7 was obtained as a yellow powder in 61.6%
yield (69.8 mg). 1H NMR (400 MHz, methanol-d4, 60 °C): δ 68.18 (s,
2H, Δν1/2 = 380.0 Hz, PyHm); 15.84 (s, 1H, Δν1/2 = 62.6 Hz, PyHp);
−2.35 (s, 6H, Δν1/2 = 122 Hz, NCMe); −5.68 (s, 2H, Δν1/2 = 45.8
Hz, ArHp); −7.49 (s, 4H, Δν1/2 = 450 Hz, ArHo). Anal. Calcd for
C21H15Cl2F4N3Ni: C, 48.98; H, 2.94; N, 8.16. Found: C, 47.85; H,
3.09; N, 8.14.
1
product was obtained in 55% yield (59.3 mg). H NMR (400 MHz,
CDCl3, 60 °C): δ 72.49 (s, 2H, Δν1/2 = 122.1 Hz, PyHm); 19.63 (s,
1H, Δν1/2 = 27.4 Hz, PyHp); 14.95 (s, 4H, Δν1/2 = 30.5 Hz, ArHm),
0.004 (s, 4H, Δν1/2 = 283.2 Hz, ArHo); −2.51 (s, 4H, Δν1/2 = 61.1 Hz,
NCMe). Anal. Calcd for C21H17Cl2F2N3Ni: C, 52.66; H, 3.58; N,
8.77. Found: C, 50.84; H, 3.87; N, 9.59.
1147
dx.doi.org/10.1021/om201213v | Organometallics 2012, 31, 1143−1149

Organometallics
Article
[2,6-bis[1-(2-trifluoromethyl-4-fluorophenylimino)ethyl]-
pyridine]NiCl2 (8). L8 (106.8 mg, 0.22 mmol) and NiCl2 (28.5 mg,
0.22 mmol) were dissolved in CH3CN (10 mL) and stirred for 18 h.
Using a procedure analogous to that for 6, 8 was obtained as red
complexes 5, 6, and 9. This material is available free of charge
via the Internet at http://pubs.acs.org. CCDC 854926−854928
also contain supplementary crystallographic data for this paper
(complexes 6, 5, and 9, respectively). These data can be
obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
1
crystals in 90.0% yield (122 mg). H NMR (400 MHz, methanol-d4,
60 °C): δ 64.95 (s, 2H, PyHm); 16.44 (s, 1H, PyHp); 11.46 (s, 2H,
ArHm); 11.33 (s, 2H, ArH′m); −8.6 (s, 2H, ArHo). The signal of N
CMe was not found because of overlapping with signal of the solvent
or wide broadening of this signal. The desired product crystallized as
8·CH2Cl2. Anal. Calcd for C25H20Cl4F8N3Ni: C, 42.00; H, 2.82; N,
5.88. Found: C, 43.09; H, 2.57; N, 6.06.
AUTHOR INFORMATION
Corresponding Author
*E-mail: bryliako@catalysis.ru. Fax: +7 383 330 8056.
■
[2,6-bis[1-(3-trifluoromethyl-4-fluorophenylimino)ethyl]-
pyridine]NiCl2 (9). L9 (106.8 mg, 0.22 mmol) and NiCl2 (28.5 mg,
0.22 mmol) were dissolved in CH3CN (10 mL) and stirred for 25.5 h.
Using a procedure analogous to that for 2, 9 was obtained as a yellow
ACKNOWLEDGMENTS
■
This work was supported by the Russian Foundation for Basic
Research (Grant No. 09-03-00485). We are grateful to Dr. L.
G. Echevskaya and Dr. M. A. Matsko for the GPC
measurements.
1
powder in 87.7% yield (118.7 mg). H NMR (400 MHz, CDCl3, 60
°C): δ 72.51 (s, 2H, Δν1/2 = 141.9 Hz, PyHm); 19.86 (s, 1H, Δν1/2
=
30.5 Hz, PyHp); 14.93 (s, 2H, Δν1/2 = 65.6 Hz, NCMe). The signal
of ArHo was not observed because of overlapping with signal of the
solvent or wide broadening of this signal. Anal. Calcd for
C24H18Cl2F8N3Ni: C, 44.92; H, 2.46; N, 6.83. Found: C, 44.13; H,
2.55; N, 6.23.
REFERENCES
■
(1) Novak, B. M.; Risse, W.; Grubbs, R. H. Adv. Polym. Sci. 1992,
102, 47−72.
[2,6-bis[1-(2,4,6-trifluorophenylimino)ethyl]pyridine]NiCl2 (10).
L10 (92.7 mg, 0.22 mmol) and NiCl2 (28.5 mg, 0.22 mmol) were
dissolved in CH3CN (10 mL) and stirred for 6 h. Using a procedure
analogous to that for 1, 10 was obtained as a brown powder in 89.6%
(2) Makovetskii, K. L. Vysokomelek. Soed. Ser. A & Ser. B 1994, 36,
1712−1730.
(3) Makovetsky, K. L. Vysokomelek. Soed. Ser. A & Ser. B 1999, 41,
1525−1543.
1
yield (108.6 mg). H NMR (400 MHz, methanol-d4, 60 °C): δ 65.15
(s, 2H, Δν1/2 = 362.0 Hz, PyHm); 16.26 (s, 1H, Δν1/2 = 48.8 Hz,
PyHp); 10.69 (s, 4H, Δν1/2 = 43.0 Hz, ArHm); 0.07 (s, 6H, NCMe);
−4.74 (s, 2H, Δν1/2 = 117.8 Hz, not assigned). Anal. Calcd for
C21H13Cl2F6N3Ni: C, 45.78; H, 2.38; N, 7.63. Found: C, 46.02; H,
2.56; N, 7.01.
(4) Janiak, C.; Lassahn, P. G. J. Mol. Catal. A: Chem. 2001, 166, 193−
209.
(5) Janiak, C.; Lassahn, P. G. Macromol. Rapid Commun. 2001, 22,
479−492.
(6) Lozan, V.; Lassahn, P. G.; Zhang, C. G.; Wu, B.; Janiak, C.;
Rheinwald, G.; Lang, H. Z. Naturforsch., B 2003, 58, 1152−1154.
(7) Nelkenbaum, E.; Kapon, M.; Eisen, M. S. Organometallics 2005,
24, 2645−2659.
[2,6-bis[1-(2,6-dichlorophenylimino)ethyl]pyridine]NiCl2 (11).
L11 (100 mg, 0.22 mmol) and NiCl2 (28.5 mg, 0.22 mmol) were
stirred in THF (15 mL) for 17 h. The solvent was partially removed
under reduced pressure, CH3CN (10 mL) was added, and the reaction
mixture was stirred at room temperature for 7 h and then at 50 °C for
15 min and at room temperature for 12 h. The red precipitate was
filtered off and washed with hexane. The desired product was obtained
in 78.3% yield (100 mg). 1H NMR (400 MHz, methanol-d4, 60 °C): δ
62.84 (s, 2H, Δν1/2 = 233.5 Hz, PyHm); 16.79 (s, 1H, Δν1/2 = 57.7 Hz,
(8) Makovetskii, K. L. Polym. Sci. Ser. C 2008, 50, 22−38.
(9) Blank, F.; Janiak, C. Coord. Chem. Rev. 2009, 253, 827−861.
(10) Ma, R.; Hou, Y.; Gao, J.; Bao, F. J. Macromol. Sci., Part C: Polym.
Rev. 2009, 49, 249−287.
(11) Sartori, G.; Ciampelli, F. C.; Cameli, N. Chim. Ind. (Milan)
1963, 45, 1478−1482.
PyHp); 11.79 (s, 4H, Δν1/2 = 32 Hz, ArHm); −0.15 (s, 6H, Δν1/2
=
(12) Tsujino, T.; Saegusa, T.; Furukawa. Makromol. Chem. 1965, 85,
71−79.
39.7 Hz, NCMe); −5.88 (s, 2H, Δν1/2 = 45.8 Hz, ArHp). Anal.
Calcd for C21H15Cl6N3Ni: C, 43.43; H, 2.60; N, 7.24. Found: C, 42.44;
H, 2.55; N, 6.87.
(13) Shi, Q.; Jie, S.; Zhang, S.; Yang, H.; Sun, W.-H. Macromol. Symp.
2007, 260, 74−79.
[2,6-bis[1-(2-isopropylphenylimino)ethyl]pyridine]NiCl2 (12). L12
(88.2 mg, 0.22 mmol) and NiCl2 (28.5 mg, 0.22 mmol) were stirred in
THF (10 mL) at 35 °C for 12 h. CH3CN (5 mL) was added, and the
reaction mixture was stirred at 35 °C overnight and at room
temperature for 12 h. The solvent was removed under reduced
pressure, and the solid residue was dissolved in CH2Cl2 (15 mL) and
filtered. Then the filtrate was concentrated to 3 mL, and hexane (5
mL) was layered upon the solution. The precipitate was filtered off,
washed with hexane, and dried. The desired product was obtained (as
(14) Johnson, L. K.; Killian, C. M.; Brookhart, M. J. Am. Chem. Soc.
1995, 117, 6414−6415.
(15) Small, B. L.; Brookhart, M.; Bennett, A. M. A. J. Am. Chem. Soc.
1998, 120, 4049−4050.
(16) Britovsek, G. J. P.; Gibson, V. C.; Kimberley, B. S.; Maddox, P.
J.; McTavish, S. J.; Solan, G. A.; White, A. J. P.; Williams, D. J. Chem.
Commun. 1998, 849−850.
(17) Britovsek, G. J. P.; Bruce, M.; Gibson, V. C.; Kimberley, B. S.;
Maddox, P. J.; Mastroianni, S.; McTavish, S. J.; Redshaw, C.; Solan, G.
A.; Stromberg, S.; White, A. J. P.; Williams, D. J. J. Am. Chem. Soc.
1999, 121, 8728−8740.
1
12·CH2Cl2) in 66.4% yield (77 mg). H NMR (400 MHz, CDCl3, 60
°C): δ 69.25 (s, 2H, Δν1/2 = 195 Hz, PyHm); 18.75 (s, 1H, Δν1/2
=
39.7 Hz, PyHp); 14.68 (s, 2H, Δν1/2 = 44.2 Hz, ArHm); 14.1 (s, 2H,
Δν1/2 = 38.2 Hz, ArH′m); 2.81 (s, 6H, Δν1/2 = 154.1 Hz, NCMe);
−0.67 (s, ≈12H, Δν1/2 = 262.5 Hz, iPr); −4.36 (s, 2H, Δν1/2 = 51.9
Hz, ArHp). One signal of ArHo was not observed because of
overlapping with signal of the solvent and/or impurities. Anal. Calcd
for C30H39Cl4N3Ni: C, 56.11; H, 6.12; N, 6.54. Found: C, 55.54; H,
5.97; N, 6.73.
(18) Britovsek, G. J. P.; Gibson, V. C.; Wass, D. F. Angew. Chem., Int.
Ed. 1999, 38, 428−447.
(19) Ittel, S. D.; Johnson, L. K.; Brookhart, M. Chem. Rev. 2000, 100,
1169−1203.
(20) Gibson, V. C.; Spitzmesser, S. K. Chem. Rev. 2003, 103, 283−
316.
(21) Late Transition Metal Polymerization Catalysis; Rieger, B., Baugh,
L. S., Kacker, S., Striegler, S., Eds.; Wiley-VCH: Weinheim, Germany,
2003.
(22) Bryliakov, K. P. Russ. Chem. Rev. 2007, 76, 253−277.
(23) Gibson, V. C.; Redshaw, C.; Solan, G. A. Chem. Rev. 2007, 107,
1745−1776.
(24) Bianchini, C. B.; Giambastiani, L.; Meli, A. Coord. Chem. Rev.
2010, 254, 431−455.
ASSOCIATED CONTENT
■
S
* Supporting Information
Figures, tables, and CIF files giving NMR spectra of Ni
complexes at variable temperature, MWD and NMR data for
polynorbornene samples, and the molecular structures of
1148
dx.doi.org/10.1021/om201213v | Organometallics 2012, 31, 1143−1149

Organometallics
Article
(25) Delferro, M.; Marks, T. J. Chem. Rev. 2011, 111, 2450−2485.
(26) Sacchi, M. C.; Sonzogni, M.; Losio, S.; Forlini, F.; Locatelli, P.;
Tritto, I.; Licchelli, M. Macromol. Chem. Phys. 2001, 202, 2052−2058.
(27) Chen, J.; Huang, Y.; Li, Z.; Zhang, Z.; Wie, C.; Lan, T.; Zhang,
W. J. Mol. Catal. 2006, 259, 133−141.
(28) Huang, Y.; Chen, J.; Chi, L.; Wei, C.; Zhang, Z.; Li, Z.; Li, A.;
Zhang, L. J. Appl. Polym. Sci. 2009, 112, 1486−1495.
(29) Talsi, E. P.; Babushkin, D. E.; Semikolenova, N. V.; Zudin, V.
N.; Panchenko, V. N.; Zakharov, V. A. Macromol. Chem. Phys. 2001,
202, 2046−2051.
(30) Semikolenova, N. V.; Zakharov, V. A.; Talsi, E. P.; Babushkin, D.
E.; Sobolev, A. P.; Echevskaya, L. G.; Khusniyarov, M. M. J. Mol. Catal.
A: Chem. 2002, 182, 283−294.
(31) Bryliakov, K. P.; Semikolenova, N. V.; Zudin, V. N.; Zakharov,
V. A.; Talsi, E. P. Catal. Commun. 2004, 5, 45−48.
(32) Bryliakov, K. P.; Semikolenova, N. V.; Zakharov, V. A.; Talsi, E.
P. Organometallics 2004, 23, 5375−5378.
(33) Bryliakov, K. P.; Talsi, E. P.; Semikolenova, N. V.; Zakharov, V.
A. Organometallics 2009, 28, 3225−3232.
(34) Semikolenova, N. V.; Zakharov, V. A.; Echevskaja, L. G.;
Matsko, M. A.; Bryliakov, K. P.; Talsi, E. P. Catal. Today 2009, 144,
334−340.
(35) Soshnikov, I. E.; Semikolenova, N. V.; Bushmelev, A. N.;
Bryliakov, K. P.; Lyakin, O. Yu.; Redshaw, C.; Zakharov, V. A.; Talsi, E.
P. Organometallics 2009, 28, 6003−6013.
(36) Chen, Y.; Qian, C.; Sun, J. Organometallics 2003, 22, 1231−
1236.
(55) A spectacular exception is complex 4 (containing a small and
strongly electron-withdrawing ortho substituent, entry 9), which was
the most reactive of all complexes.
(56) Lassahn, P. G.; Janiak, C.; Oh, J. S. Macromol. Rapid Commun.
2002, 23, 16−20.
(57) Berchtold, B.; Lozan, V.; Lassahn, P. G.; Janiak, C. J. Polym. Sci.,
Polym. Chem. 2002, 40, 3604−3614.
(58) Yang, H.; Sun, W.-H.; Chang, F.; Li, Y. Appl. Catal. A: Gen.
2003, 252, 261−267.
(59) Tarte, N. H.; Cho, H. Y.; Woo, S. I. Macromolecules 2007, 40,
8162−8167.
(60) Wang, X.; Liu, S.; Jin, G. X. Organometallics 2004, 23, 6002−
6007.
(61) Wang, H. Y.; Jin, G. X. Eur. J. Inorg. Chem. 2005, 1665−1670.
(62) Carlini, C.; Martinelli, M.; Galletti, A. M. R.; Sbrana, G. J. Polym.
Sci., Part A: Polym. Chem. 2006, 44, 1514−1521.
́
(63) Lejeune, M.; Jeunesse, C.; Matt, D.; Semeril, D.; Peruch, F.;
Toupet, L.; Lutz, P. J. Macromol. Rapid Commun. 2006, 27, 865−870.
(64) Chen, F. T.; Tang, G. R.; Jin, G. X. J. Organomet. Chem. 2007,
692, 3435−3442.
(65) Panchenko, V. N.; Semikolenova, N. V.; Danilova, I. G.;
Paukshtis, E. A.; Zakharov, V. A. J. Mol. Catal. A: Chem. 1999, 142,
27−37.
(66) Abhimanyu, O. P.; Stephen, Z.; Robert, T. S.; Steven, P. R.;
Louise, M. W. J. Polym. Sci. Part A: Polym. Chem. 2003, 41, 2095−
2106.
(67) Sheldrick, G. M. SHELXTL-97, Program for the Refinement of
Crystal Structures; University of Gottingen, Gottingen, Germany, 1997.
̈
̈
(68) Hiya, K.; Nakayama, Y.; Yasuda, H. Macromolecules 2003, 36,
(37) Chen, Y.; Chen, R.; Qian, C.; Dong, X.; Sun, J. Organometallics
7916−7922.
2003, 22, 4312−4321.
(38) Zhang, Z.; Chen, S.; Zhang, X.; Li, H.; Ke, Y.; Lu, Y.; Hu, Y. J.
Mol. Catal. A: Chem. 2005, 230, 1−8.
(39) Tellmann, K. P.; Gibson, V. C.; White, A. J. P.; Williams, D. J.
Organometallics 2005, 24, 280−286.
(40) Pelascini, F.; Peruch, F.; Lutz, P. J.; Wesolek, M.; Kress, J. Eur.
Polym. J. 2005, 41, 1288−1295.
(41) Xia, G. Y.; Li, T. C.; Zhang, A. Q. Inorg. Chem. Commun. 2010,
13, 1199−1202.
(42) Gorl, C.; Englmann, T.; Alt, H. G. Appl. Catal. A: Gen. 2011,
̈
403, 25−35.
(43) Approaches close to or similar to methods A and B had been
described previously.36−38
(44) Jesson, J. P. In NMR of Paramagnetic Molecules; La Mar, G. N.,
Horrocks, W. DeW., Jr., Holm, R. H., Eds.; Academic Press: New
York, 1973.
(45) 13C NMR data for butane-1 (100.613 MHz, toluene, 20 °C): δ
139.5 (1C, CH−), 112.5 (1C, CH2), 26.1 (1C, −CH2−), 12.3
(1C, −CH3).
(46) Sun, W.-H.; Zhang, S.; Jie, S.; Zhang, W.; Li, Y.; Ma, H.; Chen,
J.; Wedeking, K.; Frohlich, R. J. Organomet. Chem. 2006, 691, 4196−
̈
4203.
(47) Adewuyi, S.; Li, G.; Zhang, S.; Wang, W.; Hao, P.; Sun, W.-H.;
Tang, N.; Yi, J. J. Organomet. Chem. 2007, 692, 3532−3541.
(48) Zhang, M.; Zhang, S.; Hao, P.; Jie, S.; Sun, W.-H.; Li, P.; Lu, X.
Eur. J. Inorg. Chem. 2007, 3816−3826.
(49) Su, B.; Zhao, J.; Zhang, Q.; Qin, W. Polym. Int. 2009, 58, 1051−
1057.
(50) Wang, K.; Gao, R.; Hao, X.; Sun, W.-H. Catal. Commun. 2009,
10, 1730−1733.
(51) Xiao, L.; Zhang, M.; Gao, R.; Cao, X.; Sun, W.-H. Aust. J. Chem.
2010, 63, 109−115.
(52) Su, B.; Feng, G. Polym. Int. 2010, 59, 1058−1063.
(53) Yang, Y.; Yang, P.; Zhang, C.; Li, G.; Yang, X. J.; Wu, B.; Janiak,
C. J. Mol. Catal. A: Chem. 2008, 296, 9−17.
(54) Reactions carried out in toluene and heptane (over catalysts 5
and 10) yielded no polymer. A 500-fold excess of MAO (Al/Ni = 500)
was used; an increase in the Al/Ni ratio up to 1000 resulted in a
moderate drop of polymerization activity.
1149
dx.doi.org/10.1021/om201213v | Organometallics 2012, 31, 1143−1149