Oligomers and soluble polymers from the vinyl polymerization of norbornene and 5-vinyl-2-norbornene with cationic palladium catalysts

Article abstract of DOI:10.1016/j.molcata.2010.07.009

Oligomeric vinyl polynorbornene (2 to ～12 monomer units) was obtained via hydrooligomerization of norbornene (NB) using the cationic palladium complexes [Pd(PPh₃)_n(NCCH₃)_4-n] (BF₄)₂ [n = 0 (1), 3 (2)] at different hydrogen pressures. The vinyl polymerization of norbornene (NB) in the ionic liquid N-butyl-N-trimethylammonium bis(trifluoromethylsulfonyl)imide (BtMA ⁺NTf₂^-) with [Pd(NCCH₃) ₄](BF₄)₂ led to soluble polynorbornenes (with several hundred monomer units) at different temperatures and molar NB:Pd ratios. The norbornene derivative 5-vinyl-2-norbornene (VNB) was oligomerized in high yield with 1 in CH₃NO₂ primarily through the (endocyclic) norbornene double bond but also through both the norbornene and (exocyclic) vinyl double bond for about every second monomer (by ¹H NMR). A 2D ¹H,¹³C-HSQC NMR analysis suggests a β-hydrogen elimination after insertion of a norbornene double bond as chain-termination mechanism. The conversion of NB or VNB increased with temperature and a lower NB:Pd and VNB:Pd ratio, respectively. The vinyl double bond in VNB slowed down the insertion rate drastically when compared with NB (activity decrease by a factor of 10²).

Full text of DOI:10.1016/j.molcata.2010.07.009

Journal of Molecular Catalysis A: Chemical 330 (2010) 1–9
Contents lists available at ScienceDirect
Journal of Molecular Catalysis A: Chemical
journal homepage: www.elsevier.com/locate/molcata
Editor’s choice paper
Oligomers and soluble polymers from the vinyl polymerization of norbornene
and 5-vinyl-2-norbornene with cationic palladium catalysts
∗
Frederik Blank, Harald Scherer, Christoph Janiak
Institut für Anorganische und Analytische Chemie, Universität Freiburg, Albertstr. 21, D-79104 Freiburg, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 13 May 2010
Received in revised form 9 July 2010
Accepted 18 July 2010
Available online 27 July 2010
Oligomeric vinyl polynorbornene (2 to ∼12 monomer units) was obtained via hydrooligomerization of
norbornene (NB) using the cationic palladium complexes [Pd(PPh3)n(NCCH3)4−n](BF4)2 [n = 0 (1), 3 (2)] at
different hydrogen pressures. The vinyl polymerization of norbornene (NB) in the ionic liquid N-butyl-N-
+
−
trimethylammonium bis(trifluoromethylsulfonyl)imide (BtMA NTf2 ) with [Pd(NCCH3)4](BF4)2 led to
soluble polynorbornenes (with several hundred monomer units) at different temperatures and molar
NB:Pd ratios. The norbornene derivative 5-vinyl-2-norbornene (VNB) was oligomerized in high yield
with 1 in CH3NO2 primarily through the (endocyclic) norbornene double bond but also through both
Keywords:
Polymerization
Oligomerization
Hydrooligomerization
Norbornene
1
the norbornene and (exocyclic) vinyl double bond for about every second monomer (by H NMR). A 2D
1
13
H, C-HSQC NMR analysis suggests a ␤-hydrogen elimination after insertion of a norbornene double
bond as chain-termination mechanism. The conversion of NB or VNB increased with temperature and a
lower NB:Pd and VNB:Pd ratio, respectively. The vinyl double bond in VNB slowed down the insertion
Palladium
2
rate drastically when compared with NB (activity decrease by a factor of 10 ).
©
2010 Elsevier B.V. All rights reserved.
1
. Introduction
The use of olefin oligomers as intermediates for specialty chem-
icals, versatile feedstocks and building blocks drives the interest
in the catalytic oligomerization (e.g., SHELL-higher-olefin-process,
SHOP) [11–13]. In addition, olefin oligomerization is used to study
mechanistic aspects because of the homogeneity of the reaction
mixture (no heterogenation through polymer precipitation) and
because in some aspects the oligomeric products are easier to
investigate than high-molar-mass polymers [13,14]. The forma-
tion of olefin chains according to Eq. (1) is categorized as follows:
dimerization when n = 2, oligomerization when 2 < n < 100 and
polymerization when n > 100 [11].
Bicyclo[2.2.1]hept-2-ene, better known as norbornene (NB) can
be polymerized by three different mechanisms (Fig. 1) [1].
Vinyl polynorbornene (PNB) is of special interest [2] due to
its good mechanical strength, heat resistivity, and optical trans-
parency, for example, for deep ultraviolet (193 nm) photoresist
binder resins in lithographic processes [3], interlevel dielectrics in
microelectronics applications, or as a cover layer for liquid-crystal
displays [4,5]. Nickel and palladium complexes initiate the vinyl
polymerization of norbornene in combination with methylalumi-
noxane (MAO) or the Lewis acid tris(pentafluorophenyl)borane
[
[
[
B(C F5) ] with or without triethylaluminium as cocatalysts
1,6]. An exception is cationic palladium(II) complexes, such as
6 3
Pd(NCCH ) ](BF ) (1) and [Pd(PPh ) (NCCH )](BF ) (2), which
3
4
4
2
3
3
3
4 2
require no cocatalyst for their activation towards the vinyl poly-
merization of norbornene because of the weakly bound acetonitrile
ligands [1,7–9]. Also, palladium and nickel catalysts in particular
allow the polymerization of functionalized norbornene monomers
(
1)
Norbornene was oligomerized with the system TiCl /AlEt Cl at
C [15]. The hydrooligomerization of norbornene, that is, the
4
2
[
1,3,10].
◦
0
norbornene C–C bond coupling in the presence of H , with rac-
2
ꢀ
ꢀ
Me C(Ind ) ZrCl /MAO or rac-C H (Ind H ) ZrCl /MAO was used
2
2
2
2
4
4
2
2
to deliberately obtain oligomers in order to gain insight into the
microstructure of polynorbornene. The X-ray crystal structure of
a norbornene pentamer (Fig. 2) showed that in-between the reg-
ular cis-2,3-exo vinyl/addition insertions a metallocene-catalyzed
␴-bond metathesis can take place. The syn-hydrogen on C7 (the
∗ Corresponding author. Tel.: +49 761 2036127.
E-mail address: janiak@uni-freiburg.de (C. Janiak).
1
381-1169/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.molcata.2010.07.009

2
F. Blank et al. / Journal of Molecular Catalysis A: Chemical 330 (2010) 1–9
Fig. 4. Overview over the used ionic liquids (ILs). The only IL which allowed for a
+
−
norbornene C–C bond coupling (BtMA NTf2 ) is highlighted.
oligomerization of the ␣-olefin substituted norbornene derivative
Fig. 1. Schematic representation of the three different types of polymerization of
norbornene.
5
-vinyl-2-norbornene [20].
2. Experimental
2.1. General procedures
All works involving air- and/or moisture-sensitive compounds
were carried out by using standard vacuum, Schlenk or drybox
techniques. IR spectra (KBr pellet) were measured on a Bruker
Optik IFS 25. Gel permeation chromatography (GPC) analyses were
performed on a PL-GPC 220 (2 columns, PL gel 10 ␮m MIXED-B)
with polymer solutions in 1,2,4-trichlorobenzene (concentration
Fig. 2. Norbornene pentamer from a hydrooligomerization. The norbornene which
was part of the ␴-bond metathesis is highlighted for better visibility; the order of
monomer insertion is given in the gray circles [16].
2
mg/ml). The polymer solutions were filtered (Sartorius, Minis-
art RC 15, RC-membrane, PP-housing, pore size 0.45 ␮m) prior to
◦
the GPC measurements. The GPC was measured at 140 C with an
injection volume of 200 ␮l and with a flow rate of 1 ml/min. Gas
chromatography–mass spectroscopic (GC–MS) investigations were
performed on a Hewlett Packard 5890 GC (equipped with an Ultra2
column, stationary phase cross-linked Ph–Me–silicon, length 50 m,
outer diameter 0.2 mm, inner diameter: 0.11 mm; He carrier gas)
connected with a mass-spectrometer (HP 5989A). Sample solu-
tions in acetone (0.5 ␮l) were injected with a glass syringe. Electron
impact mass spectra (EI-MS) were obtained on a Thermoelectron
TSQ 700. The 1D and 2D NMR experiments with VNB and oligo-
VNB were performed on a Bruker Avance II 400 WB spectrometer
bridgehead) of the previous to last inserted monomer interacts
with the Zr atom which in the ␴-bond metathesis becomes now
bound to C7. Thus, the chain continues with the next insertion on
the C7-bridgehead carbon atom of the previous to last monomer
[
16].
Recent work on the more difficult vinyl polymerization of
functionally substituted norbornenes shows that generally the
endo-functionalized norbornenes are polymerized more slowly
compared to the exo-analogues because of the possible coordina-
tion of the donor-containing substituent to the metal atom (Fig. 3),
which attenuates the polymerization activity. Since the synthesis of
substituted norbornenes is accomplished in a Diels–Alder reaction,
always a mixture of endo- and exo-isomers is obtained [17].
The often encountered insolubility of PNBs obtained with palla-
dium catalysts [2,6,7,9,18] makes a characterization of the polymer
molar mass and mass distribution by gel permeation chromatog-
raphy (GPC) impossible [1]. The origin of this insolubility is still
not quite clear. One possibility may be chain cross-linking due to
partial cationic polymerization. The targeted preparation of nor-
bornene oligomers or soluble polymers with palladium catalysts
may help to clarify the polymerization mechanisms.
(
400 MHz for 1H).
2.2. Materials
N-Butyl-N-trimethylammonium bis(trifluoromethylsulfonyl)
+
−
imide
(BtMA NTf2 ),
1-butyl-1-methyl-pyrrolidinium
+
−
bis(trifluoromethylsulfonyl)imide
-methyl-imidazolium tetrafluoroborate (BMIm BF
-ethyl-3-methyl-imidazolium tosylate (EMIm OTs ) (Fig. 4)
(BMPy NTf2 ),
1-butyl-
+
−
)
3
1
and
4
+
−
were obtained from IoLiTec and used without further purification.
Palladium powder (∼200 mesh, Aldrich), acetonitrile (Fluka),
nitrosonium tetrafluoroborate (Aldrich) and triphenylphosphine
We report here three concepts to obtain oligomeric or sol-
uble vinyl polynorbornene with palladium catalysts: (1) the
hydrooligomerization of norbornene in CH NO . (2) The vinyl
(Aldrich) were used as received. Nitromethane (Merck-Schuchardt)
3
2
was dried over P O10, distilled twice, degased and stored under
4
polymerization of norbornene in ionic liquids [19]. (3) The vinyl
argon. Norbornene (Aldrich) was purified by distillation and stored
under argon.
2.2.1. Tetrakis(acetonitrile)palladium(II)-bis(tetrafluoroborate),
[
Pd(NCCH ) ](BF ) (1)
3
4
4 2
The complex was prepared according to the method from
Schramm and Wayland [21] by oxidation of Pd-powder with
+
−
NO BF4 in CH CN solution. An air-sensitive yellow solid (turn-
3
ing brown within minutes upon air contact) was obtained which
−
1
was stored in a glove box under argon. Yield 61%. IR (cm ): 2322
(CN), 1100–1000, 765 ꢀ(BF ).
Fig. 3. Bonding modes for functionalized norbornene derivatives (X = coordinating
functionality).
ꢀ
4

F. Blank et al. / Journal of Molecular Catalysis A: Chemical 330 (2010) 1–9
3
2
.2.2. Mono(acetonitrile)tris(triphenylphosphine)palladium(II)-
in nitromethane (2 ml) to start the polymerization reaction. The
polymerization was stopped after 24 h by adding a methanol–HCl
mixture (10:1, 30 ml). After an additional stirring for 30 min the
polymer was separated by filtration, washed with methanol and
dried in vacuum for 5 h.
bis(tetrafluoroborate), [Pd(PPh ) (NCCH )](BF ) (2)
The catalyst was prepared as described in the literature [8c]
yielding a yellow solid which did not seem air-sensitive but was
also stored in a glove box under argon. Yield 71%. IR (cm ): 2330
ꢀ
3
3
3
4 2
−
1
1
(CN), 1100–1000 ꢀ(BF ). H NMR (CDCl ): ı = 7.4–7.2 (45 H, m),
4
3
1
.9 (3 H, s).
2
2
.3. Polymerization procedures
.3.1. General
Each oligomerization at a chosen set of parameters (catalyst,
temperature, time, pressure, and molar NB:Pd ratio) was carried
out three times to ensure reproducibility of the catalytic activi-
ties. Hydrooligomerizations were run at room temperature with
Pd complexes 1 and 2 at different hydrogen pressures. For the
norbornene oligomerizations in the ionic liquids different reaction
temperatures, reaction times and monomer/catalyst ratios were
used with complex 1. The oligomers were inter alia analyzed by
infrared spectroscopy to check for the absence of double bonds in
3
. Results and discussion
3.1. Hydrooligomerization of norbornene
Under hydrooligomerization conditions catalyst
1
proved
unstable. The palladium(II) atom was rapidly reduced by hydro-
gen to metallic palladium(0), indicative by the formation of a grey
precipitate. Metallic palladium then functions as a hydrogenation
catalyst towards double bonds. A GC–MS product analysis indi-
cated the formation of norbornane (Fig. 5). Thus, the norbornene
hydrooligomerization was not investigated further with catalyst 1.
Complex 2 did not show signs of Pd(II) reduction. A product
analysis by GC–MS did not indicate norbornane formation. Nor-
bornene hydrooligomerization with 2 was carried out at different
hydrogen pressures from 0.5 bar to 4 bar. Preliminary experiments
indicated that after 1 h quantitative norbornene oligomerization
had been reached. A sample drawn after this time and analyzed
without workup by GC–MS did not show traces of the norbornene
monomer anymore. Thus, the reaction time was set to 1 h. The
oligomer product was worked up and analyzed by GC–MS for the
low molar mass dimer and trimer fraction (Fig. 6) and by EI-MS for
the higher oligomers (n ≥ 4) (Fig. 7). The dimers and trimers were
also seen in the EI-MS, but their intensity could not be determined
accurately due to peak overlap with low molar mass fragmentation
products.
−1
the region of 1620–1680 cm to ascertain that a vinyl polymeriza-
tion instead of a ring opening metathesis polymerization (ROMP)
took place [22].
2.3.2. Reaction of norbornene and hydrogen with compound 1
A 120 ml glass Büchi Miniclave was flushed with argon, charged
with 8 ml of a 1.325 mol/l solution of norbornene (1.0 g, 10.6 mmol)
in CH NO and pressurized to 2 bar hydrogen pressure under stir-
3
2
ring to saturate the solution. After depressurizing, a solution of
(9 mg, 0.02 mmol) in CH NO2 (2 ml) was quickly added with a
1
3
syringe through a ball valve against a positive pressure of hydrogen,
followed by immediate re-pressurizing to a preset starting value of
0.5 bar, 1 bar, 2 bar or 4 bar. A grey precipitate developed. After 1 h
the pressure was released. The grey suspension was filtered and
the highly viscous grey residue in the filter paper was treated three
times with 15 ml each of methanol to remove the catalyst residues.
The clear yellow filtrate was analyzed by GC–MS.
For each hydrogen pressure the lowest mass oligomer of nor-
bornene was the dimer followed by the trimer. Higher chain lengths
were identified bei EI-MS. Fig. 7 illustrates the intensities from EI-
MS as a function of monomer units at different hydrogen pressures.
We want to make it very clear that this does not reflect the oligomer
2
.3.3. Hydrooligomerization of norbornene with compound 2
The Büchi Miniclave was prepared as before with a solution of
2
(22.2 mg, 0.02 mmol) in CH NO2 (2 ml) and hydrogen pressures
3
to a preset starting value of 0.5 bar, 1 bar, 2 bar or 4 bar. After 1 h
the pressure was released. The yellow suspension was filtered and
the highly viscous colorless residue in the filter paper was treated
three times with 15 ml of methanol each to remove the catalyst
residues. The highly viscous colorless oil was dried in vacuo for 5 h
and analyzed by GC– and EI-MS.
2.3.4. Poly-/oligomerization of norbornene in ionic liquids
A 25 ml Schlenk-flask was charged with norbornene (0.5 g,
.3 mmol) and the respective ionic liquid (2 ml) and thermostated
5
to a specified temperature in an oil bath. Then, a defined but vari-
able amount of the solid complex 1 (1.0 mg, 0.0023 mmol; 4.5 mg,
0.0101 mmol; 9.0 mg, 0.0202 mmol) was added against a positive
pressure of argon. The polymerization was stopped after different
reaction times by addition of methanol (10 ml). The yellow sus-
pension was filtered and washed three times with 15 ml each of
methanol to remove the catalyst residues. The colorless solid was
dried in vacuo for 5 h.
2.3.5. Oligomerization of 5-vinyl-2-norbornene
A Schlenk-flask was charged with 5-vinyl-2-norbornene (1.28 g,
0.6 mmol), nitromethane (8 ml) was added and thermostated to
1
a specified temperature in an oil bath. Then, a defined amount of
complex 1 (15.0 mg, 0.033 mmol; 30.0 mg, 0.066 mmol; 60.0 mg,
Fig. 5. Chromatogram from GC–MS of the product from 1/H2 in nitromethane indi-
cating the norbornane formation. Peaks were assigned from the MS fragmentation
pattern.
0.135 mmol or 120.0 mg, 0.265 mmol) was added as a solution

4
F. Blank et al. / Journal of Molecular Catalysis A: Chemical 330 (2010) 1–9
Fig. 6. GC–MS graph shows the dimers and trimers of norbornene obtained by the
hydrooligomerization of norbornene with 2/H2.
distribution. The intensity of the higher oligomers will be lower
because of their lower vapor pressure and their easier fragmenta-
tion in the EI mode. Thus, oligomers with more than 12 monomer
units were of very low intensity and are not included anymore in
Fig. 7. We will also refrain from discussing any intensity variation
for oligomers with the same value of n for different hydrogen pres-
sures. We just displayed the oligomer intensities to show that an
increase in hydrogen pressure reduces the oligomer chain length.
For a pressure of 4 bar the longest oligomer chain consisted of 9 nor-
bornene monomer units. At a pressure of 2 bar the longest oligomer
+
−
Fig. 8. Polymerization activities for the system 1/BtMA NTf2 at different polymer-
ization temperatures (22 ◦C, 40 ◦C, and 60 ◦C), reaction times (20 min, 45 min, and
75 min) and molar monomer:catalyst (NB:Pd) ratios (2300:1, 525:1, and 262:1).
NB monomer. In other catalytic applications the dependence of
the activity on the IL chemical structure is noted [23]. Reaction
temperatures, reaction times and monomer/catalyst ratios were
varied with complex 1/IL. The results of the homopolymerization
of norbornene in the IL BtMA NTf2 are summarized in Table 1
and Fig. 8.
+
−
found by EI-MS contained 11 monomer units. Only at lower H pres-
Polymer yields or conversions increase only slightly with
extending the reaction times from 20 min over 45 to 75 min at a
given temperature and NB:Pd ratio (Table 1). As the reaction mix-
ture becomes more viscous with time and concomitant monomer
conversion the reaction rate decreases through the decrease of
monomer and the increased hindered diffusion of the NB monomer
to the active center. The NB polymerization is truly homogeneous
only at the very beginning. With PNB formation the active com-
plex becomes more and more imbedded in the polymer matrix
which represents a transfer to a heterogeneous phase, that is, a
heterogeneous active complex form, and this leads to a hindered
diffusion and diffusion-controlled reaction [24]. Consequently, the
activity decreases strongly with time when the only slightly higher
yields are divided by the more than doubled or tripled reaction time
(Fig. 8).
There is a trend of increased conversion upon lowering the
NB:Pd ratio from 2300:1 over 525:1 to 262:1 at otherwise identical
reaction conditions. The NB:Pd ratio was lowered by keeping the NB
amount and concentration the same, and increasing the amount of
catalyst and, hence, its concentration. Thus, more catalytic centers
became available per reaction volume. Still, the conversion did at
most increase by a factor of about 1.5. Thus, the activity decreased as
a mathematical artefact due to the division of the slightly increased
yield by the quadrupled 2300 to 525) and further doubled (525 to
2
sures of 0.5 and 1 bar oligomers with 12 (and more) norbornene
units were found with significant intensities. This is reasoned by
the rate increase of the hydrogen-transfer chain-termination reac-
tion with increasing H2 pressures which leads to shorter oligomer
chains.
3.2. Polymerization of norbornene in ionic liquids (ILs)
Pre-screening experiments showed compound 1 to be much
more active than compound 2 in norbornene polymerization
experiments. Furthermore, only in the IL N-butyl-N-
trimethylammonium
bis(trifluoromethylsulfonyl)imide
+
−
(
BtMA NTf ) could an active polymerization catalyst be gener-
2
+
−
+
−
ated with compound 1. In the ILs BMPy NTf , BMIm BF4 and
2
+
−
EMIm OTs no polymerization activity was observed with 1 at a
◦
temperature of 22 C (no higher temperatures investigated), even
after a polymerization time of 24 h. The catalyst inactivity in these
ILs could be due to immiscibility of these more polar ILs with the
2
62) molar catalyst amount.
The variation of activity with temperature depended on the
molar NB:Pd ratio. For an NB:Pd ratio of 2300:1 the activity
decreased with rising temperatures. For an NB:Pd ratio of 525:1
there is a clear trend of increased activity with increasing tem-
perature. This is reasoned by the opposing effects of increased
polymerization rate and catalyst decomposition in the IL upon
increased temperature. This decomposition is most pronounced for
the smallest catalyst amount, that is, the NB:Pd ratio of 2300:1.
The molar mass determination by GPC is really only meaningful
for the fully soluble polymers at NB:Pd ratios of 262:1. At higher
NB:Pd ratios the PNB was only partially soluble. Understandably
the soluble molar mass fractions then covered a rather narrow Mn
4
4
range from 1.2 × 10 g/mol to 4.7 × 10 g/mol. One can qualitatively
Fig. 7. Influence of the different hydrooligomerization conditions on the chain
lengths of the obtained norbornene oligomers.
note an increased molar mass for higher NB:Pd. Presumably, the

F. Blank et al. / Journal of Molecular Catalysis A: Chemical 330 (2010) 1–9
5
Table 1
+
− a
Polymerization of norbornene with 1 in BtMA NTf2
.
◦
4
4
Entry
Time (min)
Temp. ( C)
NB:Pd ratio
Conversion (%)
Activity (gPNB/molPd h)
Mn (×10 g/mol)
Mw (×10 g/mol)
Q = Mw/Mn
5
1
2
3
4
5
6
7
8
9
20
45
75
20
45
75
20
45
75
20
45
75
20
45
75
20
45
75
20
45
75
20
45
75
20
45
75
22
22
22
40
40
40
60
60
60
22
22
22
40
40
40
60
60
60
22
22
22
40
40
40
60
60
60
2300:1
2300:1
2300:1
2300:1
2300:1
2300:1
2300:1
2300:1
2300:1
525:1
525:1
525:1
525:1
525:1
525:1
525:1
525:1
525:1
262:1
262:1
262:1
262:1
262:1
262:1
262:1
262:1
262:1
44
52
58
32
54
40
20
39
45
40
44
56
46
43
64
69
60
73
50
57
77
44
49
59
70
60
75
2.9 × 10
2.3
3.0
2.5
4.0
3.8
3.1
3.7
3.9
4.7
2.0
2.3
2.6
1.7
3.2
1.8
1.6
1.7
1.8
1.2
1.7
1.5
1.6
1.5
1.4
1.2
1.3
1.7
12
11
14
9.7
9.8
9.7
14
13
15
7.2
11
9.7
7.2
11
6.6
6.1
6.7
6.5
4.8
6.8
7.2
5.5
4.9
5.8
3.3
4.1
6.2
5.2
3.7
5.6
2.4
2.6
3.1
3.8
3.3
3.2
3.6
4.8
3.7
4.2
3.4
3.7
3.8
3.9
3.6
4.0
4.0
4.8
3.4
3.3
4.1
2.8
3.2
3.6
5
2.5 × 10
5
1.0 × 10
5
2.1 × 10
5
1.6 × 10
4
6.9 × 10
5
1.3 × 10
5
1.1 × 10
4
7.8 × 10
4
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
6.0 × 10
4
2.9 × 10
4
2.2 × 10
4
6.8 × 10
4
2.9 × 10
4
2.5 × 10
5
1.0 × 10
4
3.9 × 10
4
2.9 × 10
4
3.7 × 10
4
1.9 × 10
4
1.5 × 10
4
3.3 × 10
4
1.6 × 10
4
1.1 × 10
4
5.1 × 10
4
2.0 × 10
4
1.5 × 10
a
Norbornene (NB, 0.5 g, 5.3 mmol), ionic liquid (2 ml), different amounts of solid 1 (1.0 mg, 0.0023 mmol; 4.5 mg, 0.0101 mmol; 9.0 mg, 0.0202 mmol) to give the different
molar NB:Pd ratios. The polymerization was stopped after different reaction times by addition of methanol (10 ml). Conversion and subsequent activity data are the average
from three polymerization runs. Molar mass determinations by GPC were carried out on a selected sample out of these three runs. The PNB obtained for a NB:Pd ratio of
2
300:1 was partly soluble, for a NB:Pd ratio of 525:1 was soluble for the most part and for a NB:Pd ratio of 262:1 was completely soluble in 1,2,4-trichlorobenzene. GPC
◦
analyses were carried out at 140 C.
insoluble PNB fraction contained even longer chains. Yet, there is
no clear trend of the molar mass with reaction time or temperature
even for the soluble PNB obtained at NB:Pd ratios of 262:1. This may
be due to opposing trends of differently increased polymerization
rate and chain-termination rates with a decrease in IL viscosity.
At NB:Pd ratios of 262:1 the range of Mn values between
active under these conditions contrary to other reports on Ni/MAO
catalysts [25]. Also, each Pd atom gives rise to about one chain. It
remains noteworthy that in the IL BtMA NTf2 soluble PNBs could
be obtained with a Pd catalyst.
+
−
3.3. Oligomerization of 5-vinyl-2-norbornene
4
4
1
.2 × 10 g/mol and 1.7 × 10 g/mol translates into average PNB
chain lengths of 127–180 monomer units. Together with a polymer
dispersion (Mw/Mn) between 3 and 4 and a monomer conversion of
typically less than 70% (less than 185 NB out of 262 NB molecules)
this indicates that the majority of Pd complexes are polymerization
It is well established that functionalized norbornene derivatives
are polymerized more slowly because donor functionalities like a
C double bond slow down the chain propagation through metal
C
coordination (cf. Fig. 3) [17,26]. Also with an inert substituent in
the 5-position, such as in 5-phenyl-2-norbornene, predominantly
the exo-isomer undergoes the polymerization reaction, that is, the
Fig. 9. Competition in the VNB double bonds coordinating to Pd; the formulation
Fig. 10. NMR assignment of exo- and endo-VNB in CDCl3. The norbornene and vinyl
olefinic resonances are highlighted in green and red color, respectively, conforming
tothegreen andred rectanglesin Figs. 11 and12. (For interpretation ofthe references
to color in this figure legend, the reader is referred to the web version of this article.).
[Pd] indicates that additional ligands can be present. The VNB–diolefin complex may
be a resting state. An exo–exo enchainment was suggested for the insertion of the
ring double bond in the vinyl NB polymerization [29].

6
F. Blank et al. / Journal of Molecular Catalysis A: Chemical 330 (2010) 1–9
Table 2
a
Polymerization of 5-vinyl-2-norbornene (VNB) with 1 in nitromethane .
◦
3
3
Entry
Temp. ( C)
VNB:Pd ratio
Conversion (%)
Activity (gpolymer/molPd h)
Mn (×10 g/mol)
Mw (×10 g/mol)
Q = Mw/Mn
1
2
3
4
5
6
7
8
9
22
40
60
22
40
60
22
40
60
22
40
60
320:1
320:1
320:1
160:1
160:1
160:1
80:1
80:1
80:1
40:1
40:1
15
25
35
32
43
55
42
65
79
60
75
87
250
393
561
256
345
440
169
260
316
120
150
178
n.a.
n.a.
n.a.
n.a.
n.a.
2.4
2.9
2.4
2.3
2.6
n.a.
2.1
n.a.
n.a.
n.a.
n.a.
n.a.
3.4
4.3
3.5
3.1
4.2
n.a.
3.2
n.a.
n.a.
n.a.
n.a.
n.a.
1.4
1.5
1.5
1.4
1.6
n.a.
1.5
1
1
1
0
1
2
40:1
a
5
-Vinyl-2-norbornene (VNB, 1.28 g, 10.6 mmol), nitromethane (8 ml), different amounts of 1 (15.0 mg, 0.033 mmol; 30.0 mg, 0.066 mmol; 60.0 mg, 0.135 mmol; 120.0 mg,
0
.265 mmol) as a solution in nitromethane (2 ml), reaction time 24 h, quenching by addition of a methanol–HCl mixture (10:1, 30 ml). Conversion and subsequent activity
data are the average from three polymerization runs. Molar mass determinations by GPC were carried out on a selected sample out of these three runs. n.a., not available.
For entries 1–5 the polymer was little soluble at room temperature. GPC analyses were carried out a room temperature.
endo-isomer is polymerized more slowly [27]. In addition, ␣-olefins
are known as chain-transfer agents in the vinyl polymerization of
norbornene to control the molar mass [27]. The insertion of the
group in the norbornene derivative 5-vinyl-2-norbornene is an
intramolecular ␣-olefin functionality.
Reaction temperatures and monomer:catalyst ratios were var-
ied with complex 1 in CH NO . Because of lower activities the
␣
-olefin into the metal–chain end can terminate the chain propa-
3
2
gation process by a ␤-hydride elimination (Fig. 9) [4,28]. The vinyl
reaction time was kept constant at 24 h. Table 2 shows the results
Fig. 11. 1H NMR spectrum in CDCl3 of (a) the olefinic region of the VNB monomer and (b) of oligo-VNB obtained under the conditions of Table 2, entry 12. Primarily the vinyl
olefinic protons (red rectangles) of the monomer can still be seen in the oligomer. The two sets of signals for each olefinic proton in the monomer with a ratio of about 1:0.45
are due to the endo- and exo-configuration of the vinyl group (cf. Fig. 10). (For interpretation of the references to color in this figure legend, the reader is referred to the web
version of this article.).

F. Blank et al. / Journal of Molecular Catalysis A: Chemical 330 (2010) 1–9
7
for the polymerization of 5-vinyl-2-norbornene (VNB) with 1. First,
the obtained activities are low, which is a consequence of the above
mentioned lower polymerization propagation of endo 5-vinyl-2-
norbornene and the therefore chosen long reaction time of 24 h.
The monomer conversions increased clearly with a decrease in the
molar VNB:Pd ratio and increasing reaction temperatures, so that
the highest conversion of 87% was observed for a molar VNB:Pd
◦
ratio of 40 and a polymerization temperature of 60 C. A depen-
dency between the average molar mass of the oligo-VNB and both
the molar VNB:Pd ratio and the temperature is not very appar-
ent. In each polymerization series with constant molar VNB:Pd
ratios the Mn values decreased slightly with higher temperatures
(
for example entries 7–9). The same effect was observed for a
constant temperature but decreasing VNB:Pd ratios (for exam-
ple entries 6, 9 and 12). Furthermore, the available GPC data
3
showed that the Mn values covered a range from 2.1 × 10 g/mol
3
to 2.9 × 10 g/mol depending on the reaction conditions. Together
3
with Mw < 4.3 × 10 g/mol and with the molar mass of the VNB
monomer (120.19 g/mol) these results clearly indicate the exis-
tence of oligo-VNB with chain lengths of an average of 20 monomer
units. The values for the molecular weight dispersion Q are around
1
.5, which argue for relative narrow molecular weight dispersion.
A dispersity of Q < 2 is common for oligomers and can be explained
by a chain length-dependent insertion mechanism [14,30]. The
resulting molecular weight dispersion is consistent with a Poisson-
dispersion.
Oligo-VNB can be analyzed by H and 13C NMR spectroscopy. For
comparison, the NMR assignment of the VNB monomer is provided
in Fig. 10.
1
The 1H NMR spectrum of oligo-VNB (Table 2, entry 12)
shows a ratio of aliphatic protons to olefinic protons of 6.6:1
(
Fig. 11). For a sole oligomerization through either the (endo-
cyclic) norbornene double bond or the (exocyclic) vinyl double
bond a ratio of the aliphatic to the olefinic proton resonances
in oligo-VNB of 3:1 or 5:1, respectively, would be expected
(
not considering the end groups) (Fig. 12). The surplus of
Fig. 12. Oligomerization modes for 5-vinyl-2-norbornene (VNB) with the resulting
H atom ratio of the aliphatic and olefinic protons.
aliphatic resonances compared to the olefinic ones leads to
the assumption, that some 5-vinyl-2-norbornene monomers are
oligomerized through both the norbornene and the vinyl dou-
ble bond, thereby leading to a fully saturated repeat unit with
no olefinic protons. This suggests that oligomerization can pro-
ceed through either of the two double bonds or through both of
them.
oligo-VNB as for the above 1H NMR (Table 2, entry 12) shows
resonances both for the norbornene and vinyl olefinic carbon
atoms (Fig. 13, blue and red rectangles, respectively, in the 2D
spectrum).
Yet, a comparison between the 1H NMR of the VNB monomer
and oligo-VNB in Fig. 11a and b, respectively shows that the
norbornene double bond was preferred for the oligomerization.
The vinyl olefinic carbon resonances clearly arise from (corre-
late with) the vinyl olefinic hydrogen atom resonances (dashed
lines to red rectangles in the 1H spectrum of Fig. 13). Yet, the
norbornene olefinic C resonances do not arise from any possibly
remaining H resonances of a norbornene–HC CH– double bond.
There is no correlation to H atom resonances above 5.9 ppm (cf.
Fig. 11). Instead, the norbonene–C C– resonances arise from weak
H atom resonances in the region of 5.2–5.8 ppm (blue rectangle
in the 1H spectrum of Fig. 13). Norbornene olefinic hydrogen reso-
nances in this region are due to a –HC C(R-chain)– moiety, that is, a
norbornene end group arising from a ␤-hydrogen elimination after
1
The corresponding H resonances of the norbornene double bond
(
green rectangles) have almost disappeared in oligo-VNB. For the
most part, the resonances in the olefinic region of oligo-VNB can
be attributed to the protons of the vinyl double bond (red rectan-
gles). An aliphatic to olefinic ratio of 7:1 is calculated if each second
VNB monomer is polymerized through both double bonds and the
other monomer through only the norbornene double bond (Fig. 12
bottom).
Furthermore, the prominent peak for the vinyl –CH CH2 pro-
ton of the endo-isomer at 5.46 ppm is much less pronounced in
oligo-VNB. This leads us to conclude that it is primarily the major
endo-isomer (endo/exo ratio of about 2/1) which is oligomerized
also through its vinyl double bond.
insertion (see insert in Fig. 13). This assignment is supported by
1
a
H NMR spectrum generator [32] and, for example, the 5.5 ppm
1
H NMR chemical shift of H-3 in 2-methyl-norbornene [33]. The
spread from ∼5.2 ppm to 5.8 ppm for the H and ∼128–133 ppm for
the C atom resonances is due to two regioisomers each for the endo-
and exo-isomer.
A
1H,13C-Heteronuclear Single Quantum Coherence (HSQC
31]) spectrum of the oligo-VNB (Fig. 13) provided further sup-
[
port on the preferential oligomerization route in VNB and also
on the end-group structure. The 13C resonances for the nor-
bornene and the vinyl double bond in VNB appear in well
separated regions of ∼132–138 ppm and around 113/144 ppm,
The monomer conversion increases with temperature and with
lowering of the molar VNB:Pd ratio (Fig. 14). The rather linear
increase with temperature is reasoned with the increased inser-
tion rate. There is no indication of catalyst decomposition up to
respectively (cf. Fig. 10). The 1H, C-HSQC spectrum of the same
13
◦
60 C, different from what was seen in ILs.

8
F. Blank et al. / Journal of Molecular Catalysis A: Chemical 330 (2010) 1–9
Fig. 13. 1H,13C-HSQC spectrum of the oligo-VNB (entry 12 in Table 2) in CDCl3.
1
13
The horizontal axis is the H spectrum, the vertical axis is the C spectrum. The
Heteronuclear Single Quantum Coherence (HSQC [31]) is a 2D experiment, which
correlates resonances of nuclei with the resonances of other nuclei by means of the
one-bond coupling between them. Crosspeak carbon signals from the norbornene-
type double bond are surrounded by a blue rectangle, those of the vinyl double
Fig. 15. Summary of the routes and conditions to oligonorbornene, soluble poly-
norbornene (PNB), and oligo(5-vinyl-2-norbornene) (oligo-VNB) with cationic
palladium catalysts.
1
bond by a red rectangle. In the H spectrum the green rectangle surrounds the
norbornene–HC CH– olefinic proton region, the red rectangles the vinyl–CH CH2
olefinic protons and the blue rectangle the protons for the norbornene chain end
group –HC C(R-chain)– (see insert). (For interpretation of the references to color in
this figure legend, the reader is referred to the web version of this article.).
4. Conclusion
Soluble and oligomeric polynorbornenes with the palladium
The VNB:Pd ratio was lowered by keeping the VNB amount
and concentration constant and increasing the amount of catalyst
and, hence, its concentration. Thus, more catalytic centers became
available per reaction volume. Starting with a low conversion the
increase was a factor of up to 2 (entries 1 and 4) but typically the
increase in conversion was less. The activity decreased as a mathe-
matical artefact due to the division of the somewhat increased yield
by the doubled molar catalyst amount (320 to 160 to 80 to 40:1) at
each stage.
As noted above, the overall activities for the oligomerization
of VNB are much lower than for unsubstituted NB, because of the
possible coordination of the vinyl substituent to the metal atom (cf.
Figs. 3 and 9).
catalysts [Pd(NCCH3)4](BF4)2 (1) or [Pd(PPh3)3(NCCH3)](BF4)2
(2) could be obtained by three different routes (Fig. 15): (1) the
hydrooligomerization of norbornene with 2 in nitromethane; (2)
by employing the ionic liquid N-butyl-N-trimethylammonium
+
−
bis(trifluoromethylsulfonyl)imide (BtMA NTf2
)
as reaction
medium for the norbornene polymerization with 1, and (3) by
using the NB derivative 5-vinyl-2-norbornene (VNB) with 1 in
CH3NO2 where a vinyl double bond slows down the insertion rate
and is also opened as part of the C–C bond formations. The oligo-
and polynorbornene products were obtained under variation of the
◦
reaction conditions like hydrogen pressure, temperature (22 C,
◦
◦
40 C, and 60 C), reaction time (20 min, 45 min, and 75 min) and
molar monomer/Pd ratio. The short chain hydrooligomers were
analyzed by GC–MS, EI-MS, the longer oligomers and polymers
by GPC. Analysis of the chain length for poly-/oligomers formed
in the IL and from 5-vinyl-2-norbornene (VNB) shows that each
Pd atom is catalytically active and gives rise to about one chain.
An NMR analysis of oligo-VNB reveals that primarily the nor-
bornene double bond is opened but that simultaneously also the
vinyl double bond, mostly of the endo-isomer, is polymerized. A
␤-hydrogen elimination after insertion of a norbornene double
bond is a possible chain-termination mechanism.
References
[
[
1] (a) F. Blank, C. Janiak, Coord. Chem. Rev. 253 (2009) 827–861;
(
(
(
b) C. Janiak, P.-G. Lassahn, V. Lozan, Macromol. Symp. 236 (2006) 88–99;
c) C. Janiak, P.-G. Lassahn, J. Mol. Catal. A: Chem. 166 (2001) 193–209;
d) B.L. Goodall, L.H. McIntosh, L.F. Rhodes, Macromol. Symp. 89 (1995)
4
21–432.
2] Recent work:
a) A. Sachse, S. Demeshko, S. Dechert, V. Daebel, A. Lange, F. Meyer, Dalton
Trans. 39 (2010) 3903–3914;
(
(
(
b) P. Hao, S. Zhang, J.-J. Yi, W.-H. Sun, J. Mol. Catal. A: Chem. 302 (2009) 1–6;
c) H.-Y. Gao, L. Pei, Y. Li, J.-K. Zhang, Q. Wu, J. Mol. Catal. A: Chem. 280 (2008)
Fig. 14. Influence of the reaction temperature and molar VNB:Pd ratio on the
81–86;
oligomerization of 5-vinyl-2-norbornene.
(d) X. Meng, G.-R. Tang, G.-X. Jin, Chem. Commun. (2008) 3178–3180;

F. Blank et al. / Journal of Molecular Catalysis A: Chemical 330 (2010) 1–9
9
(
(
e) W.-G. Jia, Y.-B. Huang, Y.-J. Lin, G.-X. Jin, Dalton Trans. (2008) 5612–5620;
f) W. Zuo, W.-H. Sun, S. Zhang, P. Hao, A. Shiga, J. Polym. Sci.: Part A: Polym.
(d) A. Kermagoret, P. Braunstein, Dalton Trans. (2008) 1564;
(e) P. Kuhn, D. Sémeril, D. Matt, M.J. Chetcuti, P. Lutz, Dalton Trans. (2007) 515;
(f) C. Bianchini, G. Giambastiani, I.G. Rios, G. Mantovani, A. Meli, A.M. Segarra,
Coord. Chem. Rev. 250 (2006) 1391;
Chem. 45 (2007) 3415–3430;
g) J. Hou, S. Jie, W. Zhang, W.-H. Sun, J. Appl. Polym. Sci. 102 (2006) 2233–2240.
(
[
3] (a) C. Chang, J. Lipian, D.A. Barnes, L. Seger, C. Burns, B. Bennett, L. Bonney,
L.F. Rhodes, G.M. Benedikt, R. Lattimer, S.S. Huang, V.W. Day, Macromol. Chem.
Phys. 206 (2005) 1988–2000;
(g) F. Speiser, P. Braunstein, L. Saussine, Acc. Chem. Res. 38 (2005) 784–793.
[14] (a) C. Janiak, K.C.H. Lange, P. Marquardt, R.-P. Krüger, R. Hanselmann, Macromol.
Chem. Phys. 203 (2002) 129;
(
b) K.H. Park, R.J. Twieg, R. Ravikiran, L.F. Rhodes, R.A. Shick, D. Yankelevich, A.
(b) C. Janiak, K.C.H. Lange, P. Marquardt, J. Mol. Catal. A: Chem. 180 (2002) 43;
(c) C. Janiak, K.C.H. Lange, P. Marquardt, R.-P. Krüger, R. Hanselmann, in:J. Sun, C.
Janiak (Eds.), Advances on Organometallic Catalysts and Olefin Polymerization
in China and Germany, Chemical Industry Press, Bejing, 2001, pp. 117–142, ch.
12.
Knoesen, Macromolecules 37 (2004) 5163–5178.
4] B. Berchtold, V. Lozan, P.-G. Lassahn, C. Janiak, J. Polym. Sci.: Part A: Polym.
Chem. 40 (2002) 3604.
5] (a) H. Ito, H.D. Truong, L.F. Rhodes, C. Chang, L.J. Langsdorf, H.A. Sidaway, K.
Maeda, S. Sumida, J. Photopolym. Sci. Technol. 17 (2004) 609–614;
[
[
[15] L. Porri, V.N. Scalera, M. Bagatti, A. Famulari, S.V. Meille, Macromol. Rapid.
Commun. 27 (2006) 1937.
[16] (a) M. Arndt, M. Gosmann, Polym. Bull. 41 (1998) 433;
(b) C. Karfilidis, H. Hermann, A. Rufi n˜ ska, B. Gabor, R.J. Mynott, G. Breitenbruch,
C. Weidenthaler, J. Rust, W. Joppek, M.S. Brookhart, W. Thiel, G. Fink, Angew.
Chem. Int. Ed. 43 (2004) 2444.
[17] (a) M. Kang, A. Sen, Organometallics 23 (2004) 5396;
(b) J.K. Funk, C.E. Andes, A. Sen, Organometallics 23 (2004) 1680.
[18] A. Sen, T.-W. Lai, J. Am. Chem. Soc. 103 (1982) 4627.
[19] (a) H. Olivier-Bourbigou, Y. Chauvin, J. Mol. Catal. A: Chem. 214 (2004) 9;
(b) J.S. Wilkes, J. Mol. Catal. A: Chem. 214 (2004) 11–17;
(c) V. Calò, A. Nacci, A. Monopoli, J. Mol. Catal. A: Chem. 214 (2004) 45–56;
(d) P. Wasserscheid, C. Hilgers, W. Keim, J. Mol. Catal. A: Chem. 214 (2004)
83–90;
(
b) T. Hoskins, W.J. Chung, A. Agrawal, J. Ludovice, C.L. Henderson, L.D. Seger,
L.F. Rhodes, R.A. Shick, Macromolecules 37 (2004) 4512–4518;
c) X.Q. Wu, H.A. Reed, Y. Wang, L.F. Rhodes, E. Elce, R. Ravikiran, R.A. Shick, C.L.
Henderson, S.A.B. Allen, P.A. Kohl, J. Electrochem. Soc. 150 (2003) H205–H213;
d) X.Q. Wu, H.A. Reed, L.F. Rhodes, E. Elce, R. Ravikiran, R.A. Shick, C.L. Hender-
son, S.A.B. Allen, P.A. Kohl, J. Appl. Polym. Sci. 88 (2003) 1186–1195;
e) N.R. Grove, P.A. Kohl, S.A.B. Allen, S. Jayaraman, R. Shick, J. Polym. Sci.: Part
B: Polym. Phys. 37 (1999) 3003;
f) A. Hideki, A. Satoshi, M. Hiroshi, M. Junichi, patent EPO445755, Equivalents
DE69129600, JP4063807, Idemitsu Kosan Co. (Jpn.) (1991);
g) T.F.A. Haselwander, W. Heitz, S.A. Krügel, J.H. Wendorff, Macromol. Chem.
(
(
(
(
(
Phys. 197 (1996) 3435, and references therein.
6] (a) F. Blank, H. Scherer, J. Ruiz, V. Rodríguez, C. Janiak, Dalton Trans. 39 (2010)
[
3
(
609–3619;
b) T. Yamamoto, C. Shikada, S. Kaita, T. Olivier, Y. Maruyama, Y. Wakatsuki, J.
Mol. Catal. A: Chem. 300 (2009) 1–7;
c) G.-R. Tang, Y.-J. Lin, G.-X. Jin, J. Polym. Sci.: Part A: Polym. Chem. 46 (2008)
89–500;
d) Y.-B. Huang, G.-R. Tang, G.-Y. Jin, G.-X. Jin, Organometallics 27 (2008)
59–269;
e) W.-J. Zhang, W.-H. Sun, B. Wu, S. Zhang, H.-W. Ma, Y. Li, J. Chen, P. Hao, J.
Organomet. Chem. 691 (2006) 4759–4767;
Selected articles from the special issue on “ionic liquids as promising alternative
media for organic synthesis and catalysis” which provide an overview or report
regioselective C–C bond forming and oligomerization reactions.
[20] E.V. Novikova, G.P. Belov, W.-H. Sun, V.R. Flid, Polym. Sci. Ser. A 48 (2006)
462–469.
[21] R.F. Schramm, B.B. Wayland, J. Chem. Soc., Chem. Commun. (1968) 898.
[22] T. Saegusa, T. Tsujino, J. Furukawa, Makromol. Chem. 78 (1964) 231.
[23] (a) S.A. Forsyth, J.M. Pringle, D.R. MacFarlane, Aust. J. Chem. 57 (2004) 113;
(b) J.M. Pringle, Aust. J. Chem. 62 (2009) 287.
(
4
(
2
(
(
(
f) T. Hu, Y.-G. Li, Y.S. Li, N.-H. Hu, J. Mol. Catal. A: Chem. 253 (2006) 155;
g) J. Hou, W.-H. Sun, D. Zhang, L. Chen, W. Li, D. Zhao, H. Song, J. Mol. Catal. A:
[24] C. Janiak, K.C.H. Lange, U. Versteeg, D. Lentz, P.H.M. Budzelaar, Chem. Ber. 129
(1996) 1517.
Chem. 213 (2005) 221–233;
h) T.J. Woodman, Y. Sarazin, S. Garratt, G. Fink, M. Bochmann, J. Mol. Catal. A:
Chem. 235 (2005) 88;
i) H. Gao, J. Zhang, Y. Chen, F. Zhu, Q. Wu, J. Mol. Catal. A: Chem. 240 (2005)
78;
j) H. Yang, Z. Li, W.-H. Sun, J. Mol. Catal. A: Chem. 206 (2003) 23.
7] (a) A. Sen, T.-W. Lai, R.R. Thomas, J. Organomet. Chem. 358 (1988) 567;
b) T.-W. Lai, A. Sen, Organometallics 1 (1982) 415.
8] (a) N. Seehof, C. Mehler, S. Breunig, W. Risse, J. Mol. Catal. 76 (1992) 219;
[25] C. Janiak, P.-G. Lassahn, Polym. Bull. 47 (2002) 539.
[26] (a) S. Liu, S. Borkar, D. Newsham, H. Yennawar, A. Sen, Organometallics 26
(2007) 210–216, and references therein;
(
(
1
(
(b) T. Hasan, T. Ikeda, T.J. Shiono, Polym. Sci.: Part A: Polym. Chem. 45 (2007)
4581;
(c) B. Liu, Y. Li, B.-B. Shin, D.Y. Yoon, I. Kim, L. Zhang, W. Yan, J. Polym. Sci.: Part
A: Polym. Chem. 45 (2007) 3391;
(d) K. Mueller, S. Kreiling, K. Dehnicke, J. Allgaier, D. Richter, L.J. Fetters, Y. Jung,
D.Y. Yoon, A. Greiner, Macromol. Chem. Phys. 207 (2006) 193;
(e) M.K. Boggiano, D. Vellenga, R. Carbonell, V.S. Ashby, J.M. DeSimone, Polymer
47 (2006) 4012;
[
[
(
(
(
b) C. Mehler, W. Risse, Makromol. Chem. Rapid Commun. 12 (1991) 255;
c) T.-W. Lai, A. Sen, Organometallics 3 (1984) 866.
[
9] (a) J.A. Casares, P. Espinet, G. Salas, Organometallics 27 (2008) 3761–3769;
(f) B.-G. Shin, M.-S. Jang, D.Y. Yoon, W. Heitz, Macromol. Rapid Commun. 25
(2004) 728;
(
(
b) R. López-Fernández, N. Carrera, A.C. Albéniz, P. Espinet, Organometallics 28
2009) 4996–5001.
(g) D.P. Sanders, E.F. Connor, R.H. Grubbs, R.J. Hung, B.P. Osborn, T. Chiba, S.A.
MacDonald, C.G. Willson, W. Conley, Macromolecules 36 (2003) 1534;
(h) G.M. Benedikt, E. Elce, B.L. Goodall, H.A. Kalamarides, L.H. McIntosh, L.F.
Rhodes, K.T. Selvy, C. Andes, K. Oyler, A. Sen, Macromolecules 35 (2002) 8978;
(i) R.A. Wendt, G. Fink, Macromol. Chem. Phys. 201 (2000) 1365.
[27] (a) A.S. Abu-Surrah, K. Lappalainen, M. Kettunen, T. Repo, M. Leskelä, H.A.
Hodali, B. Rieger, Macromol. Chem. Phys. 202 (2001) 599–603;
(b) C. Mehler, W. Risse, Macromol. Chem., Rapid Commun. 13 (1992) 455.
[28] PCT Int. Appl. WO 9514048, 1995, B.F. Goodrich Company (USA), invs.: B.L.
Goodall, G.M. Benedikt, L.H. McIntosh, D.A. Barnes, L.F. Rhodes, Equivalents:
Patent US 5468819, 1995, B.F. Goodrich Co. (US); Chem. Abstr. 123 (1995)
341322 p.
[29] (a) S. Ahmed, S.A. Bidstrup, P.A. Kohl, P.J. Ludovice, J. Phys. Chem. B 102 (1998)
9783–9790;
(b) S. Ahmed, P.J. Ludovice, P. Kohl, Comp. Theor. Polym. Sci. 10 (2000) 221–233;
(c) C. Janiak, P.G. Lassahn, Macromol. Rapid Commun. 22 (2001) 479–492.
[30] C. Janiak, K.C.H. Lange, P. Marquardt, Macromol. Rapid Commun. 16 (1995)
643–650.
[
10] (a) J. McDermott, C. Chang, L.F. Martin, L.F. Rhodes, G.M. Benedikt, R.P. Lattimer,
Macromolecules 41 (2008) 2984–2986;
(
4
(
b) M. Yamashita, I. Takamiya, K. Jin, K. Nozaki, Organometallics 25 (2006)
588–4595;
c) J. Lipian, R.A. Mimna, J.C. Fondran, D. Yandulov, R.A. Shick, B.L. Goodall, L.F.
Rhodes, J.C. Huffman, Macromolecules 35 (2002) 8969–8977;
d) A.D. Hennis, J.D. Polley, G.S. Long, A. Sen, D. Yandulov, J. Lipian, G.M.
(
Benedikt, L.F. Rhodes, J. Huffman, Organometallics 20 (2001) 2802–2812.
11] (a) C. Janiak, Coord. Chem. Rev. 250 (2006) 66–94;
[
[
(
b) C. Janiak, F. Blank, Macromol. Symp. 236 (2006) 14–22.
12] (a) J. Skupinska, Chem. Rev. 91 (1991) 613;
b) D. Vogt, in: B. Cornils, W.A. Herrmann (Eds.), Applied Homogeneous Catal-
ysis with Organometallic Complexes, VCH, Weinheim, Germany, 2000, pp.
45–258, ch. 2.3.1.3;
c) K. Weissermel, H.-J. Arpe, Industrial Organic Chemistry, Important Raw
Materials and Intermediates, Verlag Chemie, Weinheim, Germany, 1978;
d) G.W. Parshall, S.D. Ittel, Homogeneous Catalysis, The Applications and
Chemistry by Soluble Transition Metal Complexes, 2nd ed., Wiley, New York,
992.
13] Recent work related to SHOP:
a) Y. Yang, P. Yang, C. Zhang, G. Li, X.-J. Yang, B. Wu, C. Janiak, J. Mol. Catal. A:
Chem. 296 (2008) 9;
b) L.L. de Oliveira, R.R. Campedelli, M.C.A. Kuhn, J.-F. Carpentier, O.L.
Casagrande Jr., J. Mol. Catal. A: Chem. 288 (2008) 58;
c) A. Kermagoret, F. Tomicki, P. Braunstein, Dalton Trans. (2008) 2945;
(
2
(
(
[31] G. Bodenhausen, D.J. Ruben, Chem. Phys. Lett. 69 (1980) 185–189.
[32] ACD/HNMR Spectrum Generator, Version 4.0 for Microsoft Windows, copyright
1994–1999 by Advanced Chemistry Development Inc., Toronto, Canada.
[33] (a) W. Hückel, H.-J. Schneider, H. Schneider-Bernlöhr, Liebigs Ann. Chem. (1975)
1690–1695;
1
[
(
(
(b) J. San Filippo Jr., G.M. Anderson, J. Org. Chem. 39 (1974) 473–477;
(c) J.A. Duncan, R.T. Hendricks, K.S. Kwong, J. Am. Chem. Soc. 112 (1990)
8433–8442.
(