Reactions of cationic palladium α-diimine complexes with nitrogen-containing olefins: Branched polyethylene with carbazole functionalities

Article abstract of DOI:10.1021/om701059t

The reactivity of three nitrogen-containing olefins with a cationic (α-diimine)Pd-Me species was studied to evaluate possibilities for their catalytic copolymerization wim ethylene. Allyl dimethyl amine gives 1,2-insertion into the Pd-Me bond, but the resulting five-membered chelate is inert toward ethylene. Olefins bearing carbazole substituents insert to form three-membered chelate complexes after a chainwalking process. These chelates are reactive toward ethylene, and N-pentenylcarbazole was successfully copolymerized with ethylene to yield branched polyethylene copolymers bearing carbazole functionalities. The fluorescence of these copolymers is dependent on the amount of incorporated comonomer.

Full text of DOI:10.1021/om701059t

2052
Organometallics 2008, 27, 2052–2057
Reactions of Cationic Palladium r-Diimine Complexes with
Nitrogen-Containing Olefins: Branched Polyethylene with Carbazole
Functionalities
Weidong Li,†,‡ Xiaochun Zhang,†,‡ Auke Meetsma,† and Bart Hessen*,†,‡
Center for Catalytic Olefin Polymerization, Stratingh Institute for Chemistry, UniVersity of Groningen,
Nijenborgh 4, 9747 AG Groningen, The Netherlands, and Dutch Polymer Institute (DPI),
P.O. Box 906, 5600 AX EindhoVen, The Netherlands
ReceiVed October 21, 2007
The reactivity of three nitrogen-containing olefins with a cationic (R-diimine)Pd-Me species was studied
to evaluate possibilities for their catalytic copolymerization with ethylene. Allyl dimethyl amine gives
1,2-insertion into the Pd-Me bond, but the resulting five-membered chelate is inert toward ethylene.
Olefins bearing carbazole substituents insert to form three-membered chelate complexes after a chain-
walking process. These chelates are reactive toward ethylene, and N-pentenylcarbazole was successfully
copolymerized with ethylene to yield branched polyethylene copolymers bearing carbazole functionalities.
The fluorescence of these copolymers is dependent on the amount of incorporated comonomer.
Scheme 1
Introduction
The introduction of (polar) functionalities into polyolefin
materials by the catalytic copolymerization of simple olefins
such as ethylene and propylene with olefins bearing function-
alities has been a research topic of considerable interest.1
Although conceptionally straightforward, its practical imple-
mentation has to contend with two considerable difficulties: (a)
competition of the functionality with the olefin for binding to
the catalyst metal center (exacerbated after comonomer insertion
by the possibility of intramolecular coordination to give stable
chelates) and (b) irreversible reactions of the polar functionality
with the polarized metal–carbon bond in the catalyst. A fruitful
approach has been to use a soft Lewis-acidic metal in the catalyst
species, and the cationic palladium catalyst [(DAD)PdMe(OEt2)]-
successfully be copolymerized with ethylene.4 Here we describe
the reactivity toward some nitrogen-containing olefins. Results
include the characterization of an unusual type of three-membered
chelate complex and the successful synthesis of branched poly-
ethylene copolymers bearing carbazole functionalities.
Results and Discussion
[BArF ] (DAD ) ArNdCMe-CMedNAr, Ar ) 2,6-iPr2C6H3;
Reaction with Allyl Dimethyl Amine (ADA). Using the
method described by Brookhart and co-workers to generate
chelate complexes resulting from methyl acrylate insertion into
the Pd-Me bond,2b (DAD)PdMeCl (DAD ) ArNdCMe-
CMedNAr, Ar ) 2,6-iPr2C6H3) was reacted with NaBArF4 (ArF
) 3,5-(CF3)2C6H3) in the presence of allyl dimethyl amine
(ADA) in diethyl ether solvent. This afforded the chelate
4
ArF ) 3,5-(CF3)2C6H3) was successfully used to copolymerize
ethylene with methyl acrylate to yield branched copolymers,
albeit at modest productivities.2 Subsequently, this catalyst
system has been employed with various functionalized comono-
mers, with varying rates of success.3 In order to reveal the
potential of this approach, we have tried to study in a more
systematic fashion the reactivity of the cationic [(DAD)PdMe]+
species with functionalized olefins. Earlier we described the
reactivity toward the oxygen-containing olefins allyl methyl
ether and acrolein dimethyl acetal, where the latter could
complex [(DAD)Pd(CH2CHMeCH2NMe2)][BArF ] (1, Scheme
4
1) in 52% isolated yield. The compound was characterized by
single-crystal X-ray diffraction (Figure 1). It shows a five-
membered chelate ring resulting from 1,2-insertion of the ADA
olefinic moiety into the Pd-Me bond, although a certain amount
of conformational disorder appears to be present in the chelate
ring (judging from the relatively large thermal parameters;
attempts to model this in this fragment were not successful).
The Pd-N12 bond distance of the nitrogen atom that is trans
to the chelate alkyl carbon is, at 2.215(4) Å, noticeably longer
than the one trans to the amine donor (Pd-N11 ) 2.078(4)
Å). The room-temperature NMR spectra of 1 in CD2Cl2 solvent
show a fully asymmetric structure, with two diastereotopic
methyl groups of the coordinated NMe2 moiety. The methyl
* Corresponding author. E-mail: B.Hessen@rug.nl.
† University of Groningen.
‡ DPI.
(1) (a) Boffa, L. S.; Novak, B. M. Chem. ReV. 2000, 100, 1479. (b)
Ittel, S. D.; Johnson, L. K.; Brookhart, M. Chem. ReV. 2000, 100, 1169. (c)
Mecking, S. Angew. Chem., Int. Ed. 2001, 40, 534.
(2) (a) Johnson, L. K.; Mecking, S.; Brookhart, M. J. Am. Chem. Soc.
1996, 118, 267. (b) Mecking, S.; Johnson, L. K.; Wang, L.; Brookhart, M.
J. Am. Chem. Soc. 1998, 120, 888. (c) Arthur, S. D.; Brookhart, M. S. U.S.
Patent 5891963, 1999. (d) Geprags, M.; Mülhaupt R. WO Patent 9947569,
1998.
(3) (a) Luo, S.; Jordan, R. F. J. Am. Chem. Soc. 2006, 128, 12072. (b)
Correia, S. G.; Marques, M. M.; Ascenzo, J. R.; Ribeiro, A. F. G.; Gomes,
P. T.; Dias, A. R.; Blais, M.; Rausch, M. D.; Chien, J. C. W. J. Polym.
Sci., Part A 1999, 37, 2471.
1
group formerly bound to Pd shows a characteristic upfield H
(4) Li, W.; Zhang, X.; Meetsma, A.; Hessen, B. J. Am. Chem. Soc. 2004,
126, 12246.
10.1021/om701059t CCC: $40.75
2008 American Chemical Society
Publication on Web 04/10/2008

Cationic Pd Catalysts with N-Containing Olefins
Organometallics, Vol. 27, No. 9, 2008 2053
Figure 1. Molecular structure of [(DAD)Pd(CH2CHMeCH2NMe2)][BArF ] (1). Thermal ellipsoids are at the 50% probability level. Selected
4
bond distances (Å) and angles (deg): Pd11-N11 ) 2.078(4), Pd11-N12 ) 2.152(4), Pd11-N13 ) 2.091(5), Pd11-C134 ) 2.023(6),
N11-Pd11-N12 ) 76.67(15), N13-Pd11-C134 ) 82.2(2).
Scheme 2
NMR shift at δ 0.67 ppm (d, J ) 6.8 Hz). A reaction between
the cationic Pd-Me species [(DAD)PdMe(OEt2)][BArF ]5 and
4
ADA in CD2Cl2 monitored by 1H NMR showed clean formation
of 1. Monitoring the reaction at low temperature (gradually
warming from -60 °C) did not reveal any identifiable inter-
mediates in the reaction.
Unlike the chelate complexes derived from the ether-
functionalized olefins allyl ethyl ether and acrolein dimethyl
acetal reported earlier,4 the ADA chelate complex 1 does not
effect the homopolymerization of ethylene under standard
conditions (CH2Cl2 solvent, ambient temperature, 5 bar ethyl-
ene). Thus the increased donor strength of the trialkyl amine
versus the ether renders the five-membered chelate too stable
to allow interaction with and subsequent insertion of ethylene.
Consistently, attempts to copolymerize ethylene with ADA using
at -50 °C the coordinated ether had completely been liberated
either 1 or [(DAD)PdMe(OEt2)][BArF ] as catalyst afforded no
4
and that full conversion to 2 (as only organometallic product)
polymer.
had already taken place, without any observable intermediates.
This suggests that NPC initially coordinates to Pd through the
olefinic moiety in what appears to be the rate-determining step,
Reaction with N-Pentenylcarbazole (NPC). Reaction of
[(DAD)PdMe(OEt2)][BArF ] with N-pentenylcarbazole (NPC)
4
in dichloromethane solvent at ambient temperature, followed
followed by rapid and selective 1,2-insertion into the Pd-Me
by layering with pentane, afforded red crystals of the 1:1 reaction
bond. Rapid chain-walking6 through ꢀ-H elimination, alkene
product [(DAD)Pd(η2-Me2CHCH2CH2CHNC12H8)][BArF ] (2,
4
rotation, and reinsertion then leads to the thermodynamically
most favorable state, the three-membered chelate complex 2
(Scheme 2). In this complex, the steric interference between
the carbazole moiety and the ligand substituents is minimized,
and a favorable Pd-N interaction can be obtained without the
need for significant pyramidalization of the carbazole nitrogen
Scheme 2) in 55% isolated yield. A crystal structure determi-
nation of 2 (Figure 2) revealed a three-membered chelate
structure in which the carbazole nitrogen is coordinated to Pd
and where the carbon atom in the chelate ring bears a 3-methyl-
but-1-yl substituent. The chelate ring is essentially coplanar with
the (DAD)Pd ring, with a dihedral angle C141-Pd1-N11-C113
atom. Nevertheless, this three-membered chelate in 2 is sub-
of 178.4(4)°. The carbazole nitrogen atom deviates only a little
stantially more reactive than the five-membered chelate in 1
from planarity (sum of the three C-N-C angles is 351.9°).
and is readily able to initiate the catalytic homopolymerization
of ethylene. In a typical experiment, using 1.8 µmol of 2 in 10
The NMR spectra of 2 were fully assigned, including the
connectivity in the 3-methylbut-1-yl substituent, using a com-
mL of CH2Cl2 at ambient temperature with 5 bar of ethylene
bination of 1D and 2D (COSY, HSQC, HMBC) techniques.
pressure and 17.5 h run time, 1.42 g of branched polyethylene
(45.5 kg(PE) mol-1 h-1) was obtained (Mw ) 676 500 Mw/Mn
) 2.2).
The CH group in the three-membered chelate shows resonances
at δ 4.29 ppm (1H, dd, J ) 5.7 and 7.8 Hz) and 63.81 ppm
(13C, d, J ) 160 Hz). When the reaction of [(DAD)PdMe(OEt2)]-
Reaction with N-Allyl Carbazole (NAC). In a similar
[BArF ] with NPC in CD2Cl2 was monitored by NMR spec-
4
fashion as described above for NPC, the reaction of the cationic
troscopy at temperatures from -65 °C upward, it was seen that
(6) (a) Tempel, D. J.; Johnson, L. K.; Huff, R. L.; White, P. S.;
Brookhart, M. J. Am. Chem. Soc. 2000, 122, 6686. (b) Shultz, L. H.; Tempel,
D. J.; Brookhart, M. J. Am. Chem. Soc. 2001, 123, 11539.
(5) Johnson, L. K.; Lillian, C. M.; Brookhart, M. J. Am. Chem. Soc.
1995, 117, 6414.

2054 Organometallics, Vol. 27, No. 9, 2008
Li et al.
Figure 2. Molecular structure of [(DAD)Pd(η2-Me2CHCH2CH2CHNC12H8)][BArF ] (2). Thermal ellipsoids are at the 50% probability
4
level. Selected bond distances (Å) and angles (deg): Pd1-N11 ) 2.085(3), Pd1-N12 ) 2.143(4), Pd1-N13 ) 2.104(5), Pd1-C141 )
2.015(7), N13-C129 ) 1.453(7), N13-C140 ) 1.450(8), N13-C141 ) 1.449(8), N11-Pd1-N12 ) 75.32(14), N13-Pd1-C141 )
41.1(2).
Scheme 3
chelate with an iPr substituent. Product 4a, with the nPr
substituent, derives from initial 2,1-insertion of the olefin. The
observations suggest that the shorter spacer between the olefinic
and carbazole moieties in NAC, compared to NPC, increases
the barrier to insertion into the Pd-Me bond (allowing the olefin
complex to be observed for NAC, which was not the case for
NPC under the same conditions) and erases the kinetic prefer-
ence for 1,2- versus 2,1-insertion that is displayed by NPC.
Copolymerization of Ethylene with Carbazole-Contain-
ing Monomers. The copolymerization of ethylene with the
carbazole-containing comonomers NPC and NAC was
investigated using the ADMA chelate complex {(DAD)
Pd(CH2CHMeCH(OMe)2}[BArF ] (5)4 as the introduced
4
catalyst species. In Table 1 the results are depicted for
ethylene/NPC copolymerization at ambient temperature in
dichloromethane solvent. As can be seen from the first three
entries, the addition of NPC substrate in various concentra-
tions has no detrimental effect on the catalyst productivity.
With increasing NPC concentration an increasing amount of
NPC is incorporated into the polymer. The highest NPC
incorporation (18 wt %) was obtained from an experiment at
lower ethylene pressure (2 bar). NMR spectroscopy shows that
these poly(ethylene-co-NPC) copolymer samples are branched
polyethylenes containing incorporated carbazole functionalities
palladium methyl complex [(DAD)PdMe(OEt2)][BArF ] with
4
N-allyl carbazole (NAC) in CD2Cl2 was studied by low-
temperature NMR spectroscopy. After 5 min at -50 °C, the
coordinated ether had been displaced by the substrate, but now
the initial product appears to be the alkene complex [(DAD)
PdMe(η2-CH2dCHCH2NC12H8)][BArF ] (3, Scheme 3). The 1H
4
NMR resonances of the olefinic part of bound NAC in 3 are
found at δ 4.95 (m, dCH-), 4.58 (d, J ) 14.6 Hz, dCHH),
and 4.44 (m, dCHH), compared to δ 6.07, 5.22 (d, J ) 10.3
Hz), and 5.08 (d, J ) 17.1 Hz), respectively, for free NAC.
The Pd-Me 1H resonance is a singlet at δ 0.47 ppm, showing
that no olefin insertion has taken place yet. At -50 °C a slow
sequential reaction can be observed. Warming to 0 °C takes
this to completion and reveals the formation of two products in
approximately equal amounts. They appear to be the three-
membered chelate complexes [(DAD)Pd(η2-RCHNC12H8)]-
1
and that they are free of unreacted monomer. The H NMR
spectrum of the copolymer containing 18 wt % NPC is shown
in Figure 3. It indicates that essentially all carbazole groups in
the copolymer have at least two methylene groups between the
carbazole nitrogen and the rest of the polymer chain: the
resonances for the R-CH2 group (δ 4.25 ppm) and the ꢀ-CH2
group (δ 1.85 ppm) have intensities that are equal to that of the
carbazole 4,5-protons (δ 8.10 ppm). This implies that the
carbazole functions are not incorporated into the polymer via
direct ethylene insertion into a three-membered chelate species
like 2, as this would create a secondary carbon adjacent to the
carbazole nitrogen atom. Thus, either the chain-walking process
after NPC insertion is slower than the capture of a new ethylene
[BArF ] (R ) nPr, 4a; R ) iPr, 4b; Scheme 3), related to 2,
4
but differing in the substituent on the chelate carbon atom. Like
2, product 4b arises from 1,2-insertion of the olefin into the
Pd-Me bond, leading via chain-walking to the three-membered

Cationic Pd Catalysts with N-Containing Olefins
Organometallics, Vol. 27, No. 9, 2008 2055
Table 1. Copolymerization of Ethylene with NPC Using ADMA-Chelate Complex 5 as Catalyst
NPC
(mmol)
polymer
yield (g)
productivityb
Mw
NPC content
(wt %)b
conditionsa
(kg mol-1 h-1
)
(× 10-3
)
Mw/Mn
A
A
A
B
0
3.50
3.50
4.03
0.63
13.0
13.0
15.0
11.8
186
350
259
279
1.5
1.7
1.6
3.4
0.0
1.6
5.0
2.1
3.8
6.0
18.8
a A: 13.4 µmol of 5, 15 mL of CH2Cl2, 5 bar of ethene, room temperature, 20 h run time; B: 13.4 µmol of 5, 15 mL of CH2Cl2, 2 bar of ethene,
room temperature, 4 h run time. b Note that the productivities appear relatively low due to the high catalyst concentration and long reaction times
employed to maximize the absolute polymer yield.
1
Figure 3. H NMR spectrum (CDCl3, 23 °C, 300 MHz) of a branched ethylene-NPC copolymer with 18.8 wt % NPC incorporated.
molecule, or chain-walking is fast and can occur to, as well as
from, the three-membered chelate (in the latter case enabling
ethene capture and insertion). In view of available data on
(co)polymerization with Pd R-diimine catalysts, the latter option
is deemed more likely.
UV irradiation. Two of these copolymers, with 5.0 wt % and
18.8 wt % NPC contents, were studied by emission fluorescence
spectrometry. For the copolymer with low NPC content (5.0
wt %), mainly the locally excited state of the carbazole
chromophore at 365 nm was observed (Figure 4, top). But for
the copolymer with higher NPC content (18.8 wt%), a signifi-
cantly increased emission intensity is seen around 410 nm
(Figure 4, bottom). As the copolymers produced with this
catalyst are amorphous, the carbazole groups are essentially
distributed evenly over the volume of the polymer. The ratio
of monomer versus excimer fluorescence decreases with in-
creasing NPC content of the copolymer.
In contrast with the above results with NPC, analogous
copolymerization experiments with NAC afforded only branched
polyethylene homopolymer, even under more forcing conditions
(an experiment at 50 °C, 1.1 M NAC in dichloromethane, 5
bar of ethylene after 1.5 h afforded 3.0 g of branched
polyethylene homopolymer at 59.6 kg(PE) mol-1 h-1). From
the reactions of [(DAD)PdMe(OEt2)][BArF ] with NAC and
4
NPC, described above, it appears that the barrier to insertion
into the Pd-alkyl bond is substantially higher for NAC than
for NPC. Apparently, under the applied conditions, NAC either
cannot compete with ethylene for the binding to the Pd center
or, when coordinated to the metal, is too slow to insert into the
Pd-alkyl bond to prevent its rapid displacement from the metal
center by incoming ethylene.
Experimental Section
General Procedures. All experiments were carried out under
an atmosphere of purified nitrogen using standard Schlenk and
glovebox techniques, unless mentioned otherwise. CH2Cl2 and
CD2Cl2 (Aldrich) were distilled from CaH2 prior to use. Ether,
toluene, and pentane (Aldrich, anhydrous, 99.8%) were dried by
passing over columns of Al2O3, BASF R3-11 supported Cu oxygen
scavenger, and molecular sieves (Aldrich, 4 Å) under a nitrogen
atmosphere prior to use. NMR spectra were recorded on Varian
Gemini 300/500 spectrometers in NMR tubes equipped with a
The carbazole group is known to exhibit aggregation-
dependent fluorescence behavior. Isolated N-alkylated carbazole
groups show fluorescence around 365 nm, but carbazole groups
that are closely associated show fluorescence at longer wave-
lengths (“monomer” versus “excimer” fluorescence).7 The amor-
phous ethene/NPC copolymers exhibit visible fluorescence under
1
Teflon (Young) valve. The H NMR spectra were referenced to
resonances of residual protons in the deuterated solvents, δ 5.32
ppm for CD2Cl2. The 13C NMR spectra were referenced to the
carbon resonances of the deuterated solvents, δ 53.8 ppm for
CD2Cl2. Chemical shifts are given relative to tetramethylsilane
(downfield shifts are positive); J values are given in hertz.
Assignments of the resonances of the organometallic products were
(7) (a) Solaro, R.; Galli, G.; Ledwith, A.; Chiellini, E. In Polymer
Photophysics; Phillips, D., Ed.; Chapman and Hall: New York, 1985; p
377. (b) Miyashita, T.; Matsuda, M.; Auweraer, M.; Schryver, F. C.
Macromolecules 1994, 27, 513.

2056 Organometallics, Vol. 27, No. 9, 2008
Li et al.
δ 162.13 (q, JCB ) 50.6, Cipso), 135.20 (Co), 129.31 (qq, JCF
)
31.5, JCB ) 2.9, Cm), 124.99 (q, JCF ) 273.1, CF3), 117.83 (septet,
JCF ) 3.9, Cp).
NMR Tube Scale Reactions of [(DAD)PdMe(Et2O)][BArF ]
4
with Functionalized Olefins. The R-diimine palladium complex
[(DAD)PdMe(EtO)2][BArF ] (about 0.02 mmol) was weighed into
4
an NMR tube in a drybox under N2 atmosphere. The tube was then
capped with a latex septum and taken out of the drybox. Solutions
of monomers (1 equiv) in CD2Cl2 (0.7 mL) were injected by syringe
into the NMR tube that was cooled at -196 °C by liquid N2. Upon
thawing out, the tube was shaken briefly to dissolve the palladium
complex and transferred to the precooled probe of the NMR
spectrometer. Spectra were acquired at regular temperature intervals.
Reaction of [(DAD)PdMe(Et2O)][BArF ] with N-Allylcarba-
4
zole. After 5 min at -50 °C, the coordinated ether had been
displaced by the olefinic moiety of the substrate, yielding the olefin
complex 3. Incipient insertion of NAC into the Pd-Me bond
(producing the three-membered chelate complexes 4a and 4b) was
already observed at this temperature. Upon increasing the temper-
ature, the insertion reaction progressed, until at 0 °C all of 3 had
disappeared. The ratio of the three-membered chelate complexes
4a and 4b at all stages of the reaction was about 1:1. The
assignments of the NMR spectra of 4a and 4b are supported by
2D NMR (COSY), but DAD ligand resonances could not be
assigned due to extensive overlap in the mixture. {(DAD)-
Pd(Me)[η2CH2dCHCH2N(C6H4)2]}[BArF ] (3): 1H NMR (CD2Cl2,
4
500 MHz, -55 °C) δ 8.06 (d, J ) 7.8, N(C6H3H)2), 4.95 (m,
CHH′dCH), 4.58 (d, J ) 14.6, CHH′dCH), 4.44 (m, CHH′dCH),
4.27 (d, 2H, J ) 8.4, CH2N(C6H4)2), 2.41 and 2.24 (s, 3H each,
NdCMe), 0.47 (s, 3H, PdMe). {(DAD)Pd[MeCH2CH2CHN-
Figure 4. Emission fluorescence spectrum of branched ethylene-
NPC copolymers with 5.0 wt % (top) and 18.8 wt % (bottom) NPC
incorporated. Horizontal scale: λ (nm), vertical scale: au. Excitation
wavelength: 295 nm.
(C6H4)2]}[BArF ] (4a): 1H NMR (CD2Cl2, 500 MHz, 25 °C) δ 4.32
4
(t, J ) 6.4, PdCH), 1.48 (m, 2H, MeCH2CH2), 1.08 (m, 2H,
MeCH2), 0.46 (t, 3H, J ) 6.8, MeCH2). {(DAD)Pd[Me2-
CHCHN(C6H4)2]}[BArF ] (4b): H NMR (CD2Cl2, 500 MHz, 25
1
4
°C) δ 4.18 (d, J ) 10.9, PdCH), 2.33 (m, Me2CH), 0.25 and 0.11
made using information from COSY and HSQC (heteronuclear
single quantum coherence) and/or HMBC (heteronuclear multiple
bond coherence) spectra. GPC analysis of the polymers was
performed at ambient temperature on a Spectra Physics AS 1000
LC-system using a Viscotek H-502 viscometer and a Shodex RI-
71 refractive index detector, using THF as eluent and universal
calibration with polystyrene standards. Emission fluorescence
spectra were recorded on a Perkin-Elmer LS 50B instrument from
a pressed solid sample of 13 mm diameter and 2 mm thickness at
ambient temperature. The excitation wavelength was 295 nm, with
excitation and emission widths of 10 nm and a scan rate of 100
(d, 3H each, J ) 6.4, Me2CH).
Synthesis of [(DAD)Pd(CH2CHMeCH2NMe2)][BArF ] (1). Allyl
4
dimethyl amine (0.1 mL, 1.6 mmol) was added to a solution of
(DAD)PdMeCl (157 mg, 0.29 mmol) and Na[BArF ] (210 mg, 0.24
4
mmol) in 20 mL of Et2O. The mixture was stirred at 20 °C for 3 days.
After filtration, the solvent was evaporated under vacuum. The orange
solid was washed with pentane (10 mL) three times, affording
compound 1 (225 mg, 0.15 mmol, 52%). 1H NMR (CD2Cl2, 500 MHz,
25 °C): δ 7.44–7.30 (m, 6H, Haryl), 3.00 and 2.88 (m, 4H, iPr CH),
2.41 (s, 3H, NMeMe′), 2.28 (m, 2H, CH2N), 2.21 and 2.13 (s, 3H
each, NdCMe), 1.91 (m, CH), 1.88 (s, 3H, NMeMe′), 1.75 (dd, J )
8.8, J′ ) 11.4, PdCHH’), 1.41 and 1.28–1.10 (m, 24H, iPr Me), 1.24
(PdCHH′), 0.67 (d, 3H, J ) 6.8, CHMe). 13C NMR (CD2Cl2, 126
MHz, 25 °C): δ 178.9 and 173.41 (NdCMe), 142.53 and 141.87 (Ar
nm/min. The compounds (DAD)PdMeCl (DAD
) ArNd
CMe-CMedNAr, Ar ) 2,6-iPr2C6H3),5 NaBArF (ArF ) 3,5-
4
(CF3)2C6H3),8 and {(DAD)Pd(CH2CHMeCH(OMe)2}[BArF ]4 were
4
prepared according to published procedures. NaBArF was dried
4
Cipso), 138.27, 137.99, 137.87, and 137.61 (Ar Co), 129.01 and 128.89
at 130 °C under vacuum for 6 h. [(DAD)PdMe(OEt2)][BArF ] was
4
(Ar Cp), 125.53, 125.34, 124.91, and 124.84 (Ar Cm), 76.03 (t, JCH
)
prepared using a slightly modified version of the published
procedure.5 N-Pentenylcarbazole (NPC) and N-allylcarbazole (NAC)
were synthesized from carbazole, NaH, and 5-bromopentene-1 or
allyl bromide following the procedure described by Kim et al.9 Allyl
dimethyl amine (ADA, Acros 98%) was used as received. Elemental
analyses were performed by Kolbe Mikroanalytisches Laboratorium,
123, CH2N), 52.51 (q, JCH ) 138, NMe), 49.65 (q, JCH ) 138, NMe),
43.66 (t, JCH ) 129, PdCH2), 35.61 (d, JCH ) 122, CH), 29.41, 29.22,
29.12, and 29.08 (iPr CH), 23.0 and 21.70 (NdCMe), 15.50 (q, JCH
) 129, MeCH2). Anal. Calcd for C70H76N3BF24Pd: C, 53.76; H, 4.51;
N, 2.85. Found: C, 53.4; H, 4.3; N, 2.9.
Synthesis of {(DAD)Pd[Me2CHC2H4CHN(C6H4)2]}[BArF ] (2).
4
Mülheim an der Ruhr, Germany.
–
NMR Data for [BArF
]
Anion. The 1H and 13C NMR
N-Pentenylcarbazole (13.6 mg, 0.06 mmol) was added to a solution
4
of [(DAD)PdMe(EtO)2][BArF ] (84.6 mg, 0.06 mmol) in CH2Cl2
resonances of [BArF ]- anion in CD2Cl2 are the same in the spectra
4
4
(10 mL). The solution was stirred at 20 °C overnight. After addition
of pentane (50 mL) the solution was kept at 20 °C for 2 days. Dark
red crystals (53 mg, 0.033 mmol, 55%) of 2 were isolated. 1H NMR
(CD2Cl2, 500 MHz, 25 °C): δ 7.79, 7.64, 6.99, 6.89, and 6.86 (t,
d, t, d, d, 1H each, J ) 7.5–7.9, carb), 7.5-7.3 (m, 9H, Haryl and
carb), 4.29 (dd, J ) 5.7, J′ ) 7.8, PdCH), 3.59, 2.94, 2.69, and
2.56 (septet, 1H each, J ) 6.8, iPr CH), 2.24 and 2.04 (s, 3H each,
NdCMe), 1.65, 1.64, 1.33, 1.30, 1.02, 0.99, 0.88, and 0.48 (d, 3H
for the different cationic palladium complexes at various temper-
atures. They are give here and will not be repeated in the listing of
the other spectra. 1H NMR (CD2Cl2, 500 MHz, 25 °C): δ 7.73 (s,
8H, Ho), 7.57 (s, 4H, Hp). 13C NMR (CD2Cl2, 126 MHz, 25 °C):
(8) (a) Brookhart, M.; Volpe, A. F., Jr. Organometallics 1992, 11, 3920.
(b) Bahr, S. R.; Boudjouk, P. J. Org. Chem. 1992, 57, 5545.
(9) Kim, J. K.; Hong, S. I.; Cho, H. N. Polym. Bull. 1997, 38, 169.

Cationic Pd Catalysts with N-Containing Olefins
Organometallics, Vol. 27, No. 9, 2008 2057
each, iPr Me), 1.5 (overlapping, CHHCHPd and Me2CH), 1.1
(CHHCHMe2), 1.0 (CHHCHPd), 0.53 and 0.52 (d, 3H each, J )
8.3, Me2CH), 0.48 (CHHCHMe2). 13C NMR (CD2Cl2, 126 MHz,
25 °C): δ 175.55 and 172.04 (NdCMe), 146.63, 144.47, 135.18,
132.22, 129.07, 127.66, 125.44, 124.02, 121.35, 117.85, 113.68,
and 99.89 (Ar: carbazole), 143.18 and 142.72 (Ar Cipso), 139.34,
138.05, 137.14, and 136.96 (Ar Co), 129.07 and 128.39 (Ar Cp),
128.07, 127.51, 125.23, and 124.9 (Ar Cm), 63.81 (d, JCH ) 160,
PdCH), 35.98 (t, JCH ) 124, CH2CHMe2), 30.29, 29.80, 29.37, and
29.29 (iPr CH), 28.55 (t, JCH ) 146.6, CH2CHPd), 23.16 and 21.83
(q, JCH ) 123, Me2CH), 24.59–21.83 (8C, iPr Me), 20.69 and 20.04
(q, JCH ) 127, NdCMe). Anal. Calcd for (C78H72N3BF24Pd): C,
57.67; H, 4.47; N, 2.59. Found: C, 57.62; H, 4.42; N, 2.71.
Catalytic Polymerization Experiments. The homo- and copo-
lymerizations were performed in a 50 mL glass miniclave (Büchi
AG, Switzerland) with a Teflon-coated magnetic stirrer. Before use,
the reactor was dried at 80 °C in a vacuum oven for 2 h. A typical
reaction procedure was as follows: In a nitrogen-filled glovebox,
the miniclave was charged sequentially with (1) Pd catalyst, (2)
the desired amount of comonomers (for copolymerizations), and
(3) dichloromethane. The reactor was closed, taken out of the
glovebox, put on a magnetic stirrer at room temperature, and
pressurized with ethene. The ethene pressure was kept constant
during the reaction by replenishing flow. After the specified reaction
time, the reactor was vented, and the (co)polymerization was
terminated by the addition of excess methanol. Further workup was
performed under aerobic conditions. After the reaction mixture was
stirred at room temperature for 1 h, the volatiles were evaporated
under vacuum at 40 °C and the residue was extracted with
petroleum ether. Subsequently the polymer was precipitated with
methanol and the viscous product was dried under vacuum at 80
°C overnight.
corrected for Lorentz and polarization effects, scale variation, decay,
and absorption: a multiscan absorption correction was applied, based
on the intensities of symmetry-related reflections measured at
2
different angular settings (SADABS),10 and reduced to Fo . The
structures were solved by Patterson methods, and extension of the
model was accomplished by direct methods applied to difference
structure factors using the program DIRDIF.11 The positional and
anisotropic displacement parameters for the non-hydrogen atoms
were refined. Final refinement on F2 was carried out by full-matrix
least-squares techniques.
Compound 1. Rotational disorder was present in several of the
CF3 groups of the anion, and some of them were refined using two
alternative positions. The apparent displacement factors of the
carbon atoms in the chelate C131-C134 also suggest some
conformational disorder, but this could not be satisfactorily modeled.
Compound 2. Rotational disorder was present in several of the
CF3 groups of the anion, and some of them were refined using two
alternative positions. Some conformational disorder may be present
in the 3-methylbut-1-yl substituent C142-C146 as suggested by
the relatively large displacement factors.
Acknowledgment. We thank J. Vorenkamp for perform-
ing the polymer GPC analyses and Dr. V. Krasnikov for
recording the emission fluorescence spectra. This work is
part of the Research Programme of the Dutch Polymer
Institute (DPI), project no. 110.
Supporting Information Available: Spectral data for 2 and
polymers. Crystallographic data for 1 and 2 (CIF). This material is
available free of charge via the Internet at http://pubs.acs.org.
OM701059T
X-ray Crystallography. Crystals of 1 and 2 suitable for X-ray
diffraction were obtained by recrystallization from CH2Cl2/pentane.
Crystallographic data and details of the refinements are found in
Table S-1. With inert-atmosphere handling techniques, suitable
crystals were mounted on top of a glass fiber and aligned on a
Bruker SMART APEX CCD diffractometer. Intensity data were
(10) Sheldrick, G. M. SADABS V. 2, Multi-Scan Absorption Correction
Program; University of Göttingen: Germany, 2001.
(11) Beurskens, P. T.; Beurskens, G.; Gelder, R. de; García-Granda,
S.; Gould, R. O.; Israël, R.; Smits, J. M. M. The DIRDIF-99 Program
System; Crystallography Laboratory, University of Nijmegen: The Neth-
erlands, 1999.