Investigation of steric and electronic factors of (arylsulfonyl)phosphane- palladium catalysts in ethene polymerization

Article abstract of DOI:10.1002/ejic.201000533

(Arylsulfonyl)phosphane ligands, o-Ar₂PC₆H ₄SO₃H in which Ar is phenyl (Ph), naphthyl (Np), phenanthryl (Pa), or anthracenyl (An) were prepared. These bulky phosphanes were used to generate phosphanepalladium complexes [(o-Ar₂-PC ₆H₄SO₃)PdMe(pyridine)]. These complexes catalyze ethene polymerization and yield linear polyethene. The catalytic activity of these compounds and the molecular weight of the polymer decreases in the following order: Ph > Np > Pa > An, which corresponds to increasing cone angles and decreasing basicity. Bulky sulfonated arylphosphane ligands were prepared and used to generate (arylsulfonyl)phosphane-palladium complexes. These complexes catalyze ethene polymerization yielding linear polyethene. The relationship between the catalysts' structures and their activity was discussed.

Full text of DOI:10.1002/ejic.201000533

FULL PAPER
DOI: 10.1002/ejic.201000533
Investigation of Steric and Electronic Factors of (Arylsulfonyl)phosphane-
Palladium Catalysts in Ethene Polymerization
Laurence Piche,[a] Jean-Christophe Daigle,[a] Rinaldo Poli,[b] and Jerome P. Claverie*[a]
Keywords: Phosphane ligands / Palladium / Polymerization
(Arylsulfonyl)phosphane ligands, o-Ar2PC6H4SO3H in which
Ar is phenyl (Ph), naphthyl (Np), phenanthryl (Pa), or an-
thracenyl (An) were prepared. These bulky phosphanes were
used to generate phosphanepalladium complexes [(o-Ar2-
PC6H4SO3)PdMe(pyridine)]. These complexes catalyze eth-
ene polymerization and yield linear polyethene. The catalytic
activity of these compounds and the molecular weight of the
polymer decreases in the following order: Ph Ͼ Np Ͼ Pa Ͼ
An, which corresponds to increasing cone angles and
decreasing basicity.
gand were then disclosed by Hearley et al.,[6] Goodall et
al.,[7,8] Kochi et al.,[9,10] Liu et al.,[11] Skupov et al.,[12] Luo
et al.,[13] Vela et al.,[14] and most recently Guironnet et al.[15]
Among those reports, acrylate copolymerization with
ethene was mentioned by Goodall,[7,8] Skupov,[12] and
Guironnet.[15] These studies employ the catalyst [(o-
Ar2PC6H4SO3)PdMe(L)] with Ar = o-OMePh, which corre-
sponds to the ligand originally presented by Drent.[5] The
role of the ancillary ligand L (L = pyridine,[12,16] lutidine,[17]
DMSO,[15] or allyl group[11]) on the catalytic activity has
been studied in detail. However, at this time, little is known
on the influence of the arylphosphane sulfonate structure.
We recently reported that introduction of the bulky and
electron-rich aryl groups (Ar = –{o-[2Ј,6Ј-(OMe)2C6H3]-
C6H4}) resulted in a very active catalyst that affords poly-
ethylene of high molecular weight[12] but with a modest pro-
pensity to incorporate any other monomer than ethene. We
infer that this behavior stems from the steric hindrance,
which precludes the facile coordination of any olefin larger
than ethene. Thus, it appears that there might be a trade-off
between, on one side, the high activity and high molecular
Introduction
The evolution of olefin polymerization catalysis since
Ziegler’s discovery in 1953 has involved a prolific coupling
of polymer science with organometallic chemistry. However,
there are still no commercially viable catalysts for the con-
trolled copolymerization of simple olefins with polar func-
tional monomers. Currently, commercial processes for the
copolymerization of ethene with polar functional mono-
mers such as acrylates employ free-radical processes that
require extreme pressures and afford little or no control
over polymer architecture (tacticity or crystallinity, block-
iness, molecular-weight distribution), and thus limit the
range of material performances. A need exists for new mo-
lecular catalysts capable of polymerizing polar monomers
with controlled microstructure under mild conditions.[1–3]
A significant advance was reported by Johnson et al.,[4]
who discovered that cationic palladium diimines can copo-
lymerize ethene and acrylates to afford branched copoly-
mers where the acrylate is placed in a terminal position. In
2002, Drent et al.[5] disclosed that an ill-defined catalytic
system that contained a phosphane sulfonate and a palla-
dium complex, either tris(dibenzylideneacetone)dipalla-
dium(0) or palladium(II) acetate, permits the preparation
of ethene acrylate copolymers in which the acrylates are
incorporated in main chain positions. Well-defined palla-
dium catalysts that contain a phosphane aryl sulfonate li-
∧
weights favored by bulky and electron-rich P O sulfonated
aryl ligands and, on the other side, the propensity to incor-
porate polar comonomers, which is observed with less bulky
phosphanes. To clarify this issue, we have turned our atten-
tion toward catalysts based on polyaromatic sulfonated
phosphanes o-Ar2PC6H4SO3H in which Ar is phenyl,
naphthyl (Np), phenanthryl (Pa), or anthracenyl (An).
Nonsulfonated polyaromatic phosphane analogues were
initially developed by Müller et al., who demonstrated that
their properties are changed by altering the number of aro-
matic rings associated with the phosphane.[18] These phos-
phanes become better donors as the number of aromatic
rings increases and their Tolman cone angle increases from
145° for PPh3 to 177° for PNp2Ph and 186° for PAn2Ph.
Thus, the larger phosphanes are the better donors, and we
View this journal online at
[a] NanoQAM, Quebec Center for Functional Materials, Depart-
ment of Chemistry, University of Quebec in Montreal,
Succ Centre Ville, P. O. Box 8888, Montreal, QC, H3C3P8,
Canada
Fax: +1-514-987-4054
E-mail: claverie.jerome@uqam.ca
[b] CNRS, LCC (Laboratoire de Chimie de Coordination), Uni-
versité de Toulouse, UPS, INP,
205 Route de Narbonne, 31077 Toulouse, France
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201000533.
wileyonlinelibrary.com
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L. Piche, J.-C. Daigle, R. Poli, J. P. Claverie
FULL PAPER
should expect that catalysts based on the larger phosphanes above 10 kcalmol–1, which is high enough for the structures
would be more active and generate polyethylene of high to appear as distinct species in the NMR spectroscopic ti-
molecular weight.
mescale, even at higher temperature (no coalescence ob-
served at T = 120 °C). Bis(phenanthryl)phenylphosphane[20]
shows only one resonance in the 31P NMR spectra, thereby
indicating that the presence of the ortho sulfonic acid group
Results and Discussion
The synthesis of the sulfonated arylphosphane is a one- contributes to the slow conversion between both rotamers.
pot procedure (Scheme 1). For phenyl-substituted phos- From the phosphane structures (optimized by DFT), we
phanes 1 and 2, the dilithiated salt of benzene or tolu- have calculated Tolman cone angles,[21] that is to say, the
enesulfonic acid is treated with commercial diphenylchlo- apex angle of a cylindrical cone with origin 2.28 Å from the
rophosphane. For the other phosphanes 3–5, the sulfonated center of the phosphorus atom, the sides of which just
phenyl group is introduced first upon reaction of tri- touch the van der Waals surfaces of the outermost atoms
chlorophosphane with the lithiated salt. The resulting of the organic substituents. The Tolman angles for the syn
dichlorophosphane salt is not isolated, but it is reacted di- conformers of 3 and 4 are respectively 192 and 190°,
rectly with two equivalents of the lithium salt of the desired whereas they are 206 and 207° for the anti conformers. This
aryl group. This procedure was found to be very rapid and is significantly higher than tert-butylphosphane (182°), but
reproducible as long as the benzyl sulfonic acid was suffi- slightly smaller than the highly hindered tris(2,4,6-trimeth-
ciently anhydrous. The nBuLi concentration needs also to ylphenyl)phosphane (212°). Therefore, these sulfonated ar-
be carefully adjusted, as an excess amount of nBuLi leads ylphosphanes exhibit considerable bulk. Based on the pion-
to the formation of n-butylphosphanes (as shown by MS), eering work of Mingos,[22] the availability of the P lone pair
and a default of nBuLi leads to the isolation of phosphane increases when the size of the aryl group increases, thus the
oxides (R2POH, also shown by MS).
larger phosphanes are better electron donors. Thus, the or-
der of basicity of these phosphanes is expected to be 1 ≈ 2
Ͻ 3 ≈ 4 Ͻ 5. It also corresponds to the observed ranking
for the 31P chemical shifts, which decreases from 4 ppm (1
and 2) to –30 ppm (5).
Scheme 1.
Although MS indicates the presence of one single com-
pound for ligands 3 and 4, 31P and 13C NMR spectroscopy
clearly shows the presence of two distinct species,[19] which
correspond to two possible rotational isomers (Figure 1).
Calculations by density functional theory (DFT) indicate
that the two rotamers correspond to syn and anti conforma-
tions of the aryl groups across the P atom, with energies
differing by less than 2 kcalmol–1, which is in good agree-
ment with the 80:20 proportion found by 31P NMR spec-
Figure 1. Enthalpic changes between the syn and anti conforma-
tions of phosphanes 3 and 4 as a function of the dihedral angle
C1–P–C2–C3 (D, indicated with stars). Only the lowest transition
state (TS) is shown: the other TS (located at D ≈ 0°) is at least
troscopy at room temperature. The activation barrier is several kcalmol–1 higher in energy.
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(Arylsulfonyl)phosphane-Pd Catalysts for Ethene Polymerization
The catalyst synthesis proceeds smoothly following the rial positions. This half-boat conformation has been re-
procedure highlighted in the literature.[12] The yields are in ported for the majority of aryl sulfonate catalysts,[11,14,17,23]
the following order: 1Pd ≈ 2Pd Ͼ 3Pd Ͼ 4Pd Ͼ 5Pd, which except for bulky aryl groups or when pyridine is replaced
does not follow the expected basicity of those ligands, by DMSO.[12,15]
thereby indicating that steric factors are the dominant influ-
The complete characterization of catalysts 3Pd and 4Pd
ence in determining the reactivity of these sulfonated phos- is complicated by the fact that each rotamer reacts to give
phanes towards Pd centers. For the sake of clarity, the term a separate catalyst, thus resulting in a doubling of all phos-
catalyst will be used for compounds 1Pd to 5Pd, although phane resonances (Figure 3). The analysis is further compli-
they are only catalysts once pyridine is replaced by ethene cated by the presence of two distinct exchange processes.[16]
(initiating efficiency may be vastly different for each of The first one is the exchange between bound pyridine (BP)
them). Catalysts 3Pd, 4Pd, and 5Pd are sparingly soluble in and free pyridine (FP; excess amount of 3% for 3Pd, Fig-
most common solvents except DMSO. The overall structure ure 3). It has been demonstrated that the substitution of
observed for 1Pd resembles those of other [P OPdMe(L)] pyridine proceeds by means of an associative mechanism,[16]
∧
complexes (Figure 2), with the Pd atom in a square-planar and calculation of exchange kinetic constants by NMR
environment and the Me group trans to the sulfonate group. spectroscopic lineshape analysis is a lengthy process that
The six-membered ring Pd1–P1–C131=C132–S1–O11– was not undertaken here. Therefore, we can only state that
adopts a half-boat conformation, with C111 and O13 in under the conditions of the experiment (T = 25 °C, 3Pd =
pseudoaxial positions and C121 and O12 in pseudoequato- 6ϫ10–2 molL–1, FP = 2ϫ10–3 molL–1 in [D6]DMSO), the
exchange is slow. The second one is the inversion of the six-
membered ring Pd–O–S–C=C–P. The nonsulfonated phos-
phane aryl substituents occupy a pseudoequatorial and
pseudoaxial position. For catalysts 1Pd and 2Pd, the ex-
change process is fast on the NMR spectroscopic timescale,
even at –90 °C in CD2Cl2. For catalysts 3Pd to 5Pd, the
exchange is slow. This ring-inversion process is very sensi-
tive to steric bulk. For example, for Ar = Ph(o-OMe), the
coalescence occurs at T = –80 °C with an inversion barrier
of 5.7 kcalmol–1 in CD2Cl2, whereas for Ar = Ph[o-
C6H3(2,6-OMe)2] coalescence occurs at T = –20 °C and the
barrier is 8.3 kcalmol–1 in CD2Cl2 (see the Supporting In-
formation).
All the catalysts are able to polymerize C2H4 at 85 °C (P
= 300 psi), with the activity decreasing from 1Pd to 5Pd.
The resulting polymers are highly linear, as shown by 13C
NMR spectroscopy and by examination of the Mark–Hou-
wink plot in triple-detection gel permeation chromatog-
Figure 2. ORTEP view of 1Pd. Thermal ellipsoids are shown at the
50% probability level. Selected bond lengths [Å] and angles [°]:
Pd1–C1 2.057(10), Pd1–O11 2.164(7), Pd1–P1 2.229(3), Pd1–ⁿ1
2.110(8); C1–Pd1–N1 90.6(4), C1–Pd1–P1 89.1(3), C1–Pd1–O11
174.7(4), N1–Pd1–P1 172.4(3).
Figure 3. Superposition of 13C NMR spectra (downfield region): 1Pd: CDCl3; 3Pd and 5Pd: [D6]DMSO; T = 25 °C. For 1Pd, bound
pyridine (BP) is in rapid exchange with free pyridine (FP), whereas for 5Pd, the exchange is intermediate on the NMR spectroscopic
timescale. For 3Pd, the exchange is slow and the two rotamers are observed, as indicated by the C–SO3 resonances.
Eur. J. Inorg. Chem. 2010, 4595–4601
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L. Piche, J.-C. Daigle, R. Poli, J. P. Claverie
FULL PAPER
raphy (GPC). Unexpectedly, the drastic increase of steric Table 2. Ethene–tert-butyl acrylayte (TBA) copolymerization data
(T = 100 °C, P = 100 psi).
hindrance from 1Pd to 4Pd results in a decrease of the
[a]
PDI[a]
TBA
average molecular weight. Thus, the least bulky and more
acidic phosphane yields a catalyst with the highest activity
and produces polymers with the highest molecular weights.
Cat.
[Cat.]
[TBA]
TON
Mn
[µmolL–1] [molL–1] (molE/molPd
)
[gmol–1]
[mol-%][b]
1Pd
94
185
1.7
0.85
704
below 300
5170
3000
1.4
1.2
6
15
Contrary to what was reported by us,[12,24] we found that 2Pd
1Pd and 2Pd are also able to copolymerize acrylates with
ethene with similar activities to those obtained with
[a] Determined by GPC analysis at 160 °C in 1,2,4-trichlorobenz-
ene. [b] Determined by NMR spectroscopic analysis at 110 °C in
[D2]tetrachloroethane.
[MePd(pyridine)P(3-Me-6-SO3-C6H3)(o-OMe-Ph)2].
For
example, at P = 100 psi, T = 100 °C, and for a concentra-
tion of tert-butyl acrylate of 1.70 molL–1, an insertion of
6% was obtained with catalyst 1Pd, whereas under similar
conditions (P = 100 psi, T = 100 °C, and monomer concen-
tration: 0.85 molL–1), an insertion of 15% of tert-butyl
acrylate was observed with catalyst 2Pd. The molecular
weights of the polymers (ca. 9500 gmol–1) and copolymers
(ca. 4000 gmol–1) prepared with catalysts 1Pd and 2Pd are
approximately twice as low as those previously obtained
with [MePd(pyridine)P(3-Me-6-SO3-C6H3)(o-OMe-Ph)2].[12]
However, catalysts 3Pd, 4Pd, and 5Pd do not yield any co-
polymer under comparable conditions. Surprisingly, cata-
lyst 5Pd produces polyethylene that shows a bimodal distri-
bution, a phenomenon we cannot explain at this moment.
High activities are observed for the bulky 2-[2,6-
(MeO)2C6H3]-C6H4- aryl groups[12] but not for the bulky
groups studied here. If we use the 31P chemical shift of the
phosphane as a measure of basicity, then the basicity of
the phosphane with R = 2-[2,6-(MeO)2C6H3]-C6H4- (δ =
–2 ppm) should be close to that of 1 and 2 (δ = 4 ppm).
Polyaromatic phosphanes are more basic (δ = –25, –24, and
–29 ppm, respectively, for 3, 4, and 5). Thus, one may specu-
late that a high-activity catalyst is obtained for less basic
ligands. This is in good agreement with the observed high
activity reported for late-transition-metal polymerization
catalysts that bear electron-deficient ligands.[25,26] Further-
more, as a reviewer pointed out, for the catalyst that bears
2-[2,6-(MeO)2C6H3]-C6H4- aryl groups, the bulk is mostly
located in the axial faces.[12] By contrast, it is possible to
imagine that catalysts 3Pd to 5Pd are encumbered in the
complex plane, with the result that monomer coordination
is slowed, but with no rate decrease for β-H elimination. In
the absence of X-ray structural determination, however, this
last point is speculative (see Tables 1 and 2).
Conclusion
Phosphane sulfonate–palladium complexes were pre-
pared and used as catalysts for ethene polymerization with-
out the need for activation. Linear polyethylenes were ob-
tained with these catalysts, but acrylate–ethene copolymers
could only be obtained with 1Pd and 2Pd. Surprisingly, the
introduction of steric hindrance in the catalyst scaffold re-
sults in lower molecular weights and lower activities. The
origin of these phenomena is not totally clear at this mo-
ment. We believe that several other ligand structures will
need to be prepared and characterized before being able to
derive structure–property relationships.
Experimental Section
General: All manipulations were done under an inert atmosphere
using standard Schlenk techniques. Solvents were degassed and
dried with activated molecular sieves. Benzene and toluenesulfonic
acid were dried by azeotropic distillation with benzene. Dimeth-
yl(N,N,NЈ,NЈ-tetramethylethylenediamine)palladium(II), [PdMe2-
(tmeda)], was prepared according to de Graaf et al.[27] All acrylic
monomers were purified under argon by passing them over a bed
of inhibitor-remover resin (Aldrich) because acrylic monomers are
usually protected with quinones, which interfere with the catalyst.
The monomers were then spiked with tert-butylcatechol (0.25 wt.-
%) to prevent spontaneous radical polymerization of the acrylate
during the polymerization process. H, 13C, and 31P NMR spectra
1
were recorded with a Varian Inova 600 MHz spectrometer at ambi-
ent temperature except for the polymers, which were analyzed in
deuterated tetrachloroethane at 115 °C. The molecular-weight dis-
tributions were determined by gel permeation chromatography
(GPC) with a Viscotek HT GPC equipped with triple detection
operating at 160 °C. For lower molecular weights, the light-scat-
tering detector was not used. The eluent was 1,2,4-trichloroben-
zene, and separation was performed with three PolymerLabs Mixed
B(-LS) columns. The refractive index increment, dn/dc, of pure lin-
ear polyethylene was found to be 0.106 mLg–1 at this temperature.
Electrospray mass spectra (ESI-MS) of organic compounds were
recorded with an Agilent 6210 LC-MSD TOF mass spectrometer.
Standard numbering of polyaromatic C and H was used below.
Table 1. Ethene polymerization data (T = 85 °C; P = 300 psi; sol-
vent: toluene).
[b]
Cat.
[Cat.]
[µmolL–1] (molE/molPd
TON[a]
Polymer
wt. [g]
Mn
PDI[b]
)
[gmol–1]
1Pd
2Pd
3Pd
4Pd
5Pd
47
54
76
43
85
43ϫ103
24ϫ103
1.7ϫ103
14ϫ103
4000
11.3
7.4
0.71
3.4
9600
9300
5000
1.8
1.7
1.4
1.5
1.2
4
Preparation of the Ligand 1. 2-(Diphenylphosphanyl)-4-methylbenz-
enesulfonic Acid: nBuLi (2.5  in hexanes; 4.8 mL, 12 mmol) was
added at 0 °C to a solution of dry toluenesulfonic acid (1.03 g,
6 mmol) in THF (30 mL). After stirring for 1 h at room tempera-
ture, the solution was added dropwise to a solution of chlorodi-
phenylphosphane (1.32 g, 6 mmol) in THF (20 mL) at 0 °C. After
stirring for 4 h at room temperature, the solvent was removed in
vacuo to leave a white solid. The solid was dissolved in dichloro-
3100
0.38
3000[c]
35000
[a] TON = turnover number (E = ethene, Pd = Pd catalyst). [b] De-
termined by GPC analysis at 160 °C in 1,2,4-trichlorobenzene. Mn
= number average molecular weight; PDI = polydispersity index.
[c] Bimodal distribution.
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(Arylsulfonyl)phosphane-Pd Catalysts for Ethene Polymerization
methane (50 mL) and extracted with acidic water (2 mL of concen-
trated HCl in 30 mL of water), and then twice with water (30 mL).
The organic solvent was removed in vacuo. The product was then
recrystallized from dichloromethane/diethyl ether at –32 °C. The
7.40 (m, 2 H, H5-Np), 7.33 (m, 4 H, H7,6-Np), 7.25 (m, 2 H, H8-
Np), 7.13 (m, 1 H, H5-ArSO3), 7.01 (m, 1 H, H6-ArSO3) ppm. 13
NMR ([D6]DMSO): δ = 154.0 [JP,C = 28.8 Hz, C(SO3)], 136.8 [JP,C
= 20.9 Hz, C(P)-C(SO3)], 136.7 [C(P)-CH=CH- in ArSO3], 135.7 &
135.5 (C5-Np), 133.8 & 133.7 (C4a-Np), 133.7 [C(P)-CH=CH- in
C
1
resulting white crystals were dried in vacuo; yield 0.9 g (42%). H
NMR (CDCl3): δ = 8.15 [s, 1 H, C(P)-C(SO3)=CH-], 7.70–7.45 (m, phenyl], 132.5 [C(P)-CH=CH-CH- in phenyl], 129.2 (C8a-Np),
11 H, H4-Ph, H4-ArSO3, H2-Ph, H3-Ph), 6.96 [d, JP,H = 14 Hz, 1 129.2 (JP,C = 15 Hz, Cipso in naphthyl), 128.4 (C7-Np), 127.8 [JP,C
H, C(P)-CH=C(Me)], 2.28 (s, 3 H, CH3-ArSO3) ppm. 13C NMR
(CDCl3): δ = 150.0 (C-CH3), 140.6 (JP,C = 12.4 Hz, CSO3), 135.7
[C(P)-CH=C(Me)], 134.8 (JP,C = 11.4 Hz, Cipso in phenyl), 134.7
= 5.0 Hz, C(P)-C(SO3)-CH=], 127.2 (JP,C = 26 Hz, C2-Np), 126.6
(C4-Np), 126.4 (C3-Np), 126.19 & 126.21 (C6-Np), 134.4 (C8-Np)
ppm. 31P NMR ([D6]DMSO): δ = –23.0 (s), –26.8 (s) ppm. MS:
[JP,C = 11.0 Hz, C(P)-C(SO3)], 134.0 [JP,C = 11.4 Hz, C(P)-CH- in m/z = calcd. 442.0793; found 442.0796.
phenyl], 130.1 [JP,C = 13.1 Hz, C(P)-CH=CH-CH- in phenyl], 130.1
Preparation of Ligand 4. 2-(Diphenanthren-9-yl-phosphanyl)benz-
[JP,C = 13.1 Hz, C(P)-CH=CH-CH- in phenyl], 129.4 [-CH-
C(SO3)=C(P)], 129.3 [-CH=CH-C(SO3)=C(P)], 21.5 (ArCH3) ppm.
31P NMR (CDCl3): δ = 3.6 (s) ppm. MS: m/z = calcd. 356.0636;
found 356.0626.
enesulfonic Acid: nBuLi (2.5  in hexanes; 4.2 mL, 10.5 mmol) was
added at 0 °C to a solution of benzenesulfonic acid (0.8 g, 5 mmol)
in THF (20 mL). After stirring for 2 h at room temperature, this
solution was added dropwise to a mixture of PCl3 (0.69 g, 5 mmol)
in THF (20 mL) maintained at –78 °C. The resulting whitish sus-
pension was stirred for 1 h. In a separate Schlenk flask, nBuLi
(2.5  in hexanes; 4 mL, 10 mmol) was added to 9-bromophen-
anthrene (2.57 g, 10 mmol) in THF (30 mL) at 0 °C. This mixture
was left for one hour at room temperature and then introduced
Preparation of the Ligand 2. 2-(Diphenylphosphanyl)benzenesulfonic
Acid: nBuLi (2.5  in hexanes; 4.0 mL, 10 mmol) was added at 0 °C
to a solution of dry benzenesulfonic acid (0.80 g, 5 mmol) in THF
(25 mL). After stirring for 1 h at room temperature, the solution
was added dropwise to a solution of bis(phenyl)chlorophosphane
(1.10 g, 5 mmol) in THF (15 mL) at 0 °C. After stirring for 4 h at dropwise to the off-white suspension. After stirring for 2 h at room
room temperature, the solvent was removed in vacuo to leave a
white solid. The solid was dissolved in dichloromethane (40 mL)
and extracted with acidic water (2 mL of concentrated HCl in
30 mL of water), and then twice with degassed water (30 mL). The
organic solvent was removed in vacuo. The product was then
temperature, the solvent was removed in vacuo to leave a purple
solid. After dissolution in dichloromethane (40 mL), acidic ion-ex-
change resin [Amberlite IRC-50 (H) 16–50 mesh, 10 g] was added
and the mixture was stirred for 3 h. The supernatant was dried in
vacuo. The resulting solid, dissolved in acetonitrile, was stirred for
3 h. After filtration, the solvent was removed. The resulting pale
recrystallized from dichloromethane/diethyl ether at –32 °C. The
1
resulting white crystals were dried in vacuo; yield 0.9 g (53%). H yellowcrystals were dried invacuo; yield 1.0 g (37%). 1H NMR ([D6]-
NMR (CDCl3): δ = 8.31 [s, 1 H, C(P)-C(SO3)=CH-], 7.75–7.42 (m, DMSO): δ = 8.80–8.72 (m, 4 H, H6,5-Pa), 8.65 (m, 2 H, H7-Pa),
12 H, H4-Ph, H4-ArSO3, H5-ArSO3 H2-Ph, H3-Ph), 7.22 [m, 1 H, 8.12 (m, 1 H, H3-ArSO3), 8.02 (d, J = 7.7 Hz, 1 H, H5-ArSO3),
C(P)-CH=CH- in ArSO3] ppm. 13C NMR (CDCl3): δ = 151.8 (JP,C
= 12.0 Hz, CSO3), 134.6 (JP,C = 9.2 Hz, Cipso in phenyl), 133.5 [JP,C
7.92 (dd, J = 7.9 Hz, J = 1.2 Hz, 1 H, H4-ArSO3), 7.67 (m, 2 H,
H10-Pa), 7.62 (m, 2 H, H4-Pa), 7.45 (dd, 3J = 16.2 Hz, 3J = 7.8 Hz,
2 H, H3-Pa), 7.38 (d, J = 7.5 Hz, 2 H, H2-Pa), 7.35 (d, J = 7.7 Hz,
1 H, H6-ArSO3), 7.23 (d, J = 3.3 Hz, 2 H, H1-Pa), 7.15 (m, 2 H,
3
3
=
12.8 Hz, -C(P)-CH- in phenyl], 133.3 [C(P)-CH=CH- in
C6H4SO3], 132.8 {[C(P)-C(SO3)], 129.8 [JP,C = 10.1 Hz, -CH-
C(SO3)=C(P)], 129.3 [JP,C
phenyl], 129.3 [C(P)-CH=CH-CH- in phenyl], 128.7 [C(P)-
=
11.9 Hz, C(P)-CH=CH-CH- in H8-Pa) ppm. 13C NMR ([D6]DMSO): δ = 152.5, 134.8, 132.3,
132.2, 132.1, 132.0, 130.4, 129.8, 128.9, 128.5, 127.7, 127.6, 127.3,
127.2, 126.1, 125.7, 125.5, 125.4, 124.4, 122.0, 121.7, 121.6 ppm.
31P NMR ([D6]DMSO): δ = –22.4 (s), –24.8 (s) ppm. MS: m/z =
calcd. 542.1106; found 542.1113.
CH=CH- in ArSO3], 128.6 [JP,C
=
8.2 Hz, -CH=CH-
C(SO3)=C(P)]} ppm. 31P NMR (CDCl3): δ = 4.3 (s) ppm. MS: m/z
= calcd. 342.0480; found 342.0488.
Preparation of Ligand 3. 2-(Dinaphthalen-1-yl-phosphanyl)benz-
enesulfonic Acid: nBuLi (2.5  in hexanes; 4.2 mL, 10.5 mmol) was
added at 0 °C to a solution of benzenesulfonic acid (0.8 g, 5 mmol)
in THF (20 mL). The excess amount (0.5 mmol) was used to
quench residual water (0.5 mmol) in benzenesulfonic acid. After
stirring for 2 h at room temperature, this solution was added drop-
wise to a mixture of PCl3 (0.69 g, 5 mmol) in THF (20 mL) main-
tained at –78 °C. The resulting whitish suspension was stirred for
1 h. In a separate Schlenk flask, nBuLi (2.5  in hexanes; 4 mL,
10 mmol) was added to 9-bromonaphthalene (2.07 g, 10 mmol) in
THF (30 mL) at 0 °C. This mixture was left for one hour at room
temperature and then introduced dropwise to the off-white suspen-
sion. After stirring for 2 h at room temperature, the solvent was
removed in vacuo to leave a purple solid. After dissolution in
dichloromethane (40 mL), acidic ion-exchange resin [Amberlite
IRC-50 (H) 16–50 mesh, 10 g] was added and the mixture was
stirred for 3 h. The supernatant was dried in vacuo. The resulting
solid, dissolved in acetonitrile, was stirred for 3 h. After filtration,
the solvent was removed. The resulting white crystals were dried in
Preparation of Ligand 5. 2-(Dianthracen-9-yl-phosphanyl)ben-
zenesulfonic Acid: nBuLi (2.5  in hexanes; 5.2 mL, 13 mmol) at
0 °C was added to a solution of dry benzenesulfonic acid (0.92 g,
5.8 mmol) in THF (20 mL). After stirring for 2 h at room tempera-
ture, the solution was added dropwise to a solution of PCl3
(0.787 g, 5.8 mmol) in THF (20 mL) at –78 °C and stirred for 1 h.
In a separate Schlenk flask, nBuLi (2.5  in hexanes; 4.64 mL,
11.6 mmol) was added to 9-bromoanthracene (3.00 g, 11.6 mmol)
in THF (30 mL) at 0 °C. This mixture was left for one hour at
room temperature and then introduced dropwise to the whitish sus-
pension. After stirring for 2 h at room temperature, the solvent was
removed in vacuo to leave a purple solid. After dissolution in
dichloromethane (40 mL), acidic ion-exchange resin [Amberlite
IRC-50 (H) 16–50 mesh, 12 g] was added and the mixture was
stirred for 3 h. The supernatant was dried in vacuo. The resulting
solid, dissolved in acetonitrile, was stirred 3 h. After filtration, the
solvent was removed. The resulting dark yellow crystals were dried
1
in vacuo; yield 1.9 g (49%). H NMR ([D6]DMSO): δ = 8.45 (s, 2
H, H10-An), 8.40 (dd, 3J = 3.5 Hz, 3J = 9.1 Hz, 4 H, H1,8-An), 7.89
(d, J = 8.4 Hz, 4 H, H4,5-An), 7.44 (m, 4 H, H3,6-An), 7.31 [t, J =
7.0 Hz, 1 H, C(P)-C(SO3)=CH-CH-], 7.22 (m, 4 H, H2,7-An), 6.95
[t, J = 7.0 Hz, 1 H, C(P)-C(SO3)=CH-], 6.90 [m, 2 H, C(P)-
1
3
vacuo; yield 1.4 g (63%). H NMR ([D6]DMSO): δ = 8.14 (dd, J
3
= 7.36, J = 4.21 Hz, 1 H, H3-ArSO3), 8.10 (d, J = 7.85 Hz, 1 H,
H4-ArSO3), 7.88–7.83 (m, 2 H, H3-Np), 7.82 (d, J = 8.09 Hz, 2 H,
3
3
H2-Np), 7.46 (dd, J = 6.28 Hz, J = 3.11 Hz, 2 H, H4-Np), 7.43– CH=CH-] ppm. 13C NMR (CDCl3): δ = 153.9 (CSO3), 135.3 [C(P)-
Eur. J. Inorg. Chem. 2010, 4595–4601
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4599

L. Piche, J.-C. Daigle, R. Poli, J. P. Claverie
FULL PAPER
C(SO3)=CH-], 134.6 [C(P)-C(SO3)=CH-CH=], 134.2 [JP,C
=
= 6.50 Hz, 2 H, H meta pyridine), 0.62 (d, JP,H = 2.8 Hz, 3 H, Pd-
19.9 Hz, C(P)-CSO3], 134.2 [JP,C = 14.9 Hz, C(P)-CH=CH- in Me) ppm. 13C NMR ([D6]DMSO): δ = 154.0, 153.8, 151.8, 151.6,
ArSO3], 131.0 (C4,5-An), 129.1 (C1,8-An), 128.6 (C8a,9a-An), 127.9
[C(P)-CH=CH- in ArSO3], 127.7 (C4a,10a-An), 126.7 (JP,C
150.5, 150.3, 136.6, 135.6, 134.3, 133.7, 133.4, 133.1, 132.4, 130.6,
129.7, 129.3, 128.8, 128.3, 127.9, 127.5, 127.0, 126.5, 126.2, 126.0,
125.7, 0.5 ppm. 31P NMR ([D6]DMSO): δ = –18.0 (s), –22.2 (s)
ppm.
=
-
22.9 Hz, Cipso in An), 125.4 (C10-An), 125.1 (C2,7-An), 124.6 (C3,6
An) ppm. 31P NMR ([D6]DMSO): δ = –29.4 (s) ppm. MS: m/z =
calcd. 556.1262; found 556.1247.
Preparation of 4Pd. [MePd(pyridine)P(-6-SO3-C6H3)(phen-
anthrene)2]: [PdMe2(tmeda)] (0.063 g, 0.25 mmol) and ligand 4
(0.136 g, 0.25 mmol) were dissolved in dry THF (10 mL) under an
inert atmosphere and the resulting solution was stirred for 30 min.
Pyridine (0.02 g, 0.30 mmol) was then added followed by stirring
for another 60 min. After adding Et2O (10 mL), the light brown
precipitate was collected, washed with Et2O, and dried under vac-
uum; yield 0.076 g (41%). 1H NMR ([D6]DMSO): δ = 8.52 (d, J =
8.3 Hz, 2 H, Hortho pyridine), 8.40–8.15 [m, 4 H, C(SO3)-CH=CH-
CH=CH], 8.05–7.65 (m, 18 H, HPa), 7.57 (t, J = 7.5 Hz, 1 H, Hpara
pyridine), 7.30 (dd, J = 7.7 Hz, J = 6.9 Hz, 2 H, Hmeta pyridine),
0.63 (d, JP,H = 3.4 Hz, 3 H, Pd-Me) ppm. 13C NMR ([D6]DMSO):
δ = 152.3, 149.5, 135.3, 134.8, 132.3, 132.1, 130.4, 129.8, 128.9,
128.6, 127.8, 127.6, 127.3, 127.2, 126.4, 126.2, 125.7, 125.4, 124.4,
123.2, 122.5, 122.0, 121.7, 0.6 ppm. 31P NMR ([D6]DMSO): δ =
–8.88 (s), –11.45 (s) ppm.
Preparation of 1Pd. [MePd(pyridine)P(-3-Me-6-SO3-C6H3)(Ph)2]:
[PdMe2(tmeda)] (0.063 g, 0.25 mmol) and ligand
1 (0.089 g,
0.25 mmol) were dissolved in dry THF (10 mL) under an inert at-
mosphere and stirred for 30 min. Pyridine (0.0965 g, 1.25 mmol)
was then added followed by stirring for another 30 min. During the
stirring, a white precipitate was formed. After adding Et2O
(25 mL), the precipitate was collected, washed with Et2O, and dried
under vacuum; yield 0.100 g (72%). 1H NMR (CDCl3): δ = 8.81
(d, J = 4.9 Hz, 2 H, Hortho pyridine), 8.17 [dd, 3J = 4.5 Hz, 3J =
8.0 Hz, 1 H, C(P)-C(SO3)=CH-], 7.86 (t, J = 7.7 Hz, 1 H, Hpara
pyridine), 6.63 (m, 4 H, Hortho phenyl) 7.51 (m, 2 H, Hmeta pyr-
idine), 7.46 (m, 6 H, Hmeta + Hpara phenyl), 7.33 [d, J = 7.9 Hz, 1
H, C(P)-CH=], 6.80 [d, J = 9.5 Hz, 1 H, C(P)-CH=C(Me)-CH-],
2.25 (s, 3 H, ArCH3), 0.49 (d, JP,H = 2.63 Hz, 3 H, Pd-Me) ppm.
13C NMR (CDCl3): δ = 150.5 (N-C=C), 146.9 (JP,C = 13.7 Hz,
CSO3), 140.2 (JP,C = 6.6 Hz, C-CH3), 138.5 (br., Cipso in phenyl),
135.1 (Cpara in pyridine), 134.4 [JP,C = 12.1 Hz, C(P)-CH=CH- in
ArSO3], 131.8 [C(P)-CH=C(Me)-], 131.1 [C(P)-C(SO3)=CH-],
130.4 [C(P)-C(SO3)=CH-CH-], 130.0 [C(P)-CH=CH-CH in
phenyl], 128.8 [JP,C = 11.1 Hz, C(P)-CH=CH-CH- in phenyl], 125.2
(Cmeta in pyridine), 21.6 (ArCH3), 0.9 (CH3-Pd) ppm. 31P NMR
(CDCl3): δ = 28.9 (s) ppm.
3
3
Preparation of 5Pd. [MePd(pyridine)P(-6-SO3-C6H3)(anthracene)2]:
[PdMe2(tmeda)] (0.063 g, 0.25 mmol) and ligand
5 (0.136 g,
0.25 mmol) were dissolved in dry THF (10 mL) under an inert at-
mosphere and the resulting solution was stirred for 30 min. Pyr-
idine (0.02 g, 0.30 mmol) was then added followed by stirring for
another 60 min. After adding Et2O (10 mL), the yellow precipitate
was collected, washed with Et2O, and dried under vacuum; yield
1
0.069 g (37%). H NMR ([D6]DMSO): δ = 9.26 (d, J = 9.3 Hz, 2
Preparation of 2Pd. [MePd(pyridine)P(-6-SO3-C6H3)(Ph)2]:
[PdMe2(tmeda)] (0.113 g, 0.44 mmol) and ligand
H, Hortho pyridine), 8.96–8.65 [m, 4 H, C(SO3)-CH=CH-CH=CH],
2 (0.152 g,
3
3
8.82 (dd, J = 9.0 Hz, J = 3.5 Hz, 2 H, Hmeta pyridine), 8.52–7.50
(m, 18 H, HAn), 7.39 (t, J = 7.5 Hz, 1 H, Hpara pyridine), 0.66 (d,
JP,H = 3.0 Hz, 3 H, Pd-Me) ppm. 13C NMR ([D6]DMSO): δ =
152.9, 152.8, 152.2, 149.9, 147.3, 139.7, 136.7, 135.9, 135.7, 135.0,
134.9, 134.6, 131.8, 131.7, 130.4, 129.9, 129.8, 129.7, 129.4, 128.7,
127.6, 127.4, 127.3, 126.8, 126.7, 126.4, 126.2, 125.9, 125.7, 125.4,
0.5 ppm. 31P NMR ([D6]DMSO): δ = –19.1 (s) ppm.
0.44 mmol) were dissolved in dry THF (10 mL) under inert atmo-
sphere and the resulting solution was stirred for 30 min. Pyridine
(0.04 g, 0.50 mmol) was then added followed by stirring for another
60 min. During the stirring, a white precipitate formed. After add-
ing Et2O (25 mL), the white precipitate was collected, washed with
Et2O, and dried under vacuum; yield 0.110 g (81%). 1H NMR
(CDCl3): δ = 8.80 (d, J = 4.2 Hz, 2 H, Hortho pyridine), 8.28 [m, 1
H, -C(SO3)-CH-], 7.86 (t, J = 7.4 Hz, 1 H, Hpara pyridine), 7.63 (m,
4 H, Hortho phenyl), 7.49 (d, J = 7.1 Hz, 2 H, Hmeta pyridine), 7.45
(m, 6 H, Hmeta, Hpara phenyl), 7.36 [t, J = 7.4 Hz, 2 H, C(SO3)-
CP-CH, C(SO3)-CH=CH], 7.05 [t, J = 8.6 Hz, 1 H, C(SO3)-CP-
CH=CH], 0.50 (d, JP,H = 2.4 Hz, 3 H, Pd-Me) ppm. 13C NMR
(CDCl3): δ = 150.2 (N-C=C), 149.2 (JP,C = 13.0 Hz, CSO3), 138.1
Polymerizations: Polymerizations were carried out in a stainless
steel reactor (100 or 450 mL, Parr). Catalyst, toluene, and co-
monomer were added to a Schlenk flask in a nitrogen-filled
glovebox. The reactor, which was first dried and kept under nitro-
gen, was loaded with the toluene solution by cannula transfer from
the Schlenk flask under nitrogen. The reactor was then sealed, pres-
surized with ethene, stirred, and heated. The polymerizations were
performed at constant pressure in the feed reactor and the activities
were calculated from the rate of ethene consumption, which was
monitored by the decrease of the ethene pressure in the feed tank.
Once the reaction was over, the reactor was cooled down to room
temperature and slowly depressurized. The polymers were precipi-
tated in four volumes of methanol, collected by centrifugation or
filtered, washed with methanol, and dried under vacuum.
(br., Cipso in phenyl), 134.5 (Cpara in pyridine), 134.2 (JP,C
=
12.2 Hz, CP-CH=CH- in ArSO3), 130.9 (CP-CH=CH-CH in
phenyl), 129.9 (CP-CH=CH in ArSO3), 129.8 (JP,C = 6.9 Hz,
PC=CH in ArSO3), 129.6 [-CH-C(SO3)=CP], 128.7 [JP,C = 11.2 Hz,
C(P)-CH=CH-CH- in phenyl], 128.6 [JP,C = 7.8 Hz, -C(P)-C(SO3)-
], 125.0 (Cmeta in pyridine), 0.6 (CH3-Pd) ppm. 31P NMR (CDCl3):
δ = 29.2 (s) ppm.
Preparation of 3Pd. [MePd(pyridine)P(-6-SO3-C6H3)(naphthal-
ene)2]: [PdMe2(tmeda)] (0.063 g, 0.25 mmol) and ligand 3 (0.111 g,
0.25 mmol) were dissolved in dry THF (10 mL) under an inert at-
mosphere and the resulting solution was stirred for 30 min. Pyr-
idine (0.02 g, 0.30 mmol) was then added followed by stirring for
another 60 min. After adding Et2O (10 mL), the purple precipitate
Computational Details: All geometry optimizations were performed
with the Gaussian03 suite of programs[28] using the B3LYP func-
tional, which includes the three-parameter gradient-corrected ex-
change functional of Becke[29] and the correlation functional of
Lee, Yang, and Parr, which includes both local and nonlocal
terms.[30] The basis set chosen was the standard 6-31+G**, which
was collected, washed with Et2O, and dried under vacuum; yield
1
0.081 g (50%). H NMR ([D6]DMSO): δ = 8.58 (d, J = 7.1 Hz, 2 includes both polarization and diffuse functions. For the calcula-
H, Hortho pyridine), 8.51 [d, J = 7.6 Hz, 1 H, C(SO3)-CH-], 8.38– tion of the Tolman angle, only the zwitterionic form of the phos-
8.21 [m, 3 H, C(SO3)-CH=CH-CH=CH-], 8.08–7.71 (m, 14 H, Np- phanes was considered. Solvent effects and neutral structures (sulf-
3
3
H), 7.39 (t, J = 8.9 Hz, 1 H, Hpara pyridine), 7.34 (dd, J = 7.2, J
onic acid and nonprotonated phosphanes) were not calculated.
4600
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© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2010, 4595–4601

(Arylsulfonyl)phosphane-Pd Catalysts for Ethene Polymerization
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[19] None of the ligands show 31P,1H coupling (expected JP,H
≈
500 Hz) by either 1H or proton coupled 31P NMR spec-
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Received: May 14, 2010
Published Online: August 16, 2010
Eur. J. Inorg. Chem. 2010, 4595–4601
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4601