Synthesis of non-symmetrically sulphonated phosphine sulphonate based Pd(ii) catalyst salts for olefin polymerisation reactions

Article abstract of DOI:10.1039/c1dt10372e

Direct sulphonation of 2-(diphenylphosphino)benzenesulphonic acid was extensively studied. The non-symmetrically functionalised reaction products obtained, related to the widely applied water soluble phosphine ligands m,m,m-TPPTS and m,m-TPPDS, display ch

Full text of DOI:10.1039/c1dt10372e

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An international journal of inorganic chemistry
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Volume 40 | Number 33 | 7 September 2011 | Pages 8249–8460
ISSN 1477-9226
COVER ARTICLE
Rieger et al.
Synthesis of non-symmetrically
sulphonated phosphine sulphonate
based Pd(II) catalyst salts for olefin
polymerisation reactions
1477-9226(2011)40:33;1-S

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PAPER
Synthesis of non-symmetrically sulphonated phosphine sulphonate based
Pd(II) catalyst salts for olefin polymerisation reactions†
Timo M. J. Anselment,a Carly E. Anderson,a Bernhard Rieger,*a M. Bele Boeddinghausb and Thomas F. Fa¨sslerb
Received 4th March 2011, Accepted 3rd May 2011
DOI: 10.1039/c1dt10372e
Direct sulphonation of 2-(diphenylphosphino)benzenesulphonic acid was extensively studied. The
non-symmetrically functionalised reaction products obtained, related to the widely applied water
2
soluble phosphine ligands m,m,m-TPPTS and m,m-TPPDS, display chelating k -(P,O)-coordination to
Pd(II) metal centres. Phase transfer reaction of rac-o,m-TPPDS as the potassium salt with 18-crown-6
2
and complexation to Pd(II) gives the novel anionic catalyst precursor [K(18-crown-6)]2[k (P,O){rac-o,m-
TPPDS}PdMeCl] suitable for olefin polymerisation reactions. Ethene homo- and co-polymerisation
reactions with polar functionalised olefins were investigated with this anionic phosphine sulphonate
Pd(II)-based pre-catalyst salt.
Introduction and concept
Coordination–insertion polymerisation in the presence of polar
functionalised olefins with transition metal catalysts is normally
problematic due to their catalyst poisoning effect by strong
coordination of functional groups to the active metal site or
the decomposition of catalysts in the presence of functionalised
monomers by associated degradation pathways.1–3 Phosphine
sulphonate-based Pd(II) catalysts have proved to be the most
versatile system for copolymerisation reactions of numerous polar
functionalised olefins e.g. methyl acrylate2 with ethene (Fig. 1) as
Fig. 1 General structure of phosphine sulphonate Pd(II)-based a) neutral
catalysts stabilised by base; e.g. pyridine, lutidine, dmso b) anionic
pre-catalyst with chloro ligand.
well as for non-alternating copolymerisation of ethene and CO.4–5
Late transition metal catalysts bearing phosphine sulphonate
ligands are able to form linear random copolymers with polar
functionalised olefins,6–9 unlike insertion copolymerisation with
a-diimine based catalysts10–11 or radical copolymerisation.2 Their
bases.6 However most modifications of the ligand backbone
versatility has been demonstrated by previously unprecedented
have not been successful in increasing the polar olefin insertion
incorporation of comonomers such as acrylonitrile,12–13 vinyl
ratio in copolymerisation reactions.9,24–25 A concept to decrease
acetate,14 vinyl fluoride,15–16 alkyl vinyl ethers,17 vinyl sulphones18
catalyst poisoning s-coordination of polar groups by anionic
and very recently acrylic acid, as well as allylic functionalised
substituents on the ligand backbone and thus favour required p-
coordination, originates from work by Ziegler et al.26 and Piers
et al.27 Recent reports on a bis-ortho-sulphonated triarylpho-
sphine-based Pd(II) catalyst system, which assembles as a
tetrameric aggregate, by Jordan et al.16,28 indicate increased
incorporation of vinyl fluoride. However, the presence of two
possibly competing ortho-sulphonate functionalities is anticipated
to severely influence the reaction mechanism, for example, chain
transfer and monomer coordination. Therefore, introduction of
anionic functionalities in positions outside of the direct coordina-
tion environment at the ligand backbone is desired.
olefins,19 with the insertion mechanism being the subject of numer-
ous theoretical studies.13,20–23 Unfortunately the catalyst structure–
activity relationship is still not clearly understood, apart from the
stabilising and competing effects of the employed coordinating
aWACKER-Lehrstuhl fu¨r Makromolekulare Chemie der Technischen
Universita¨t Mu¨nchen, Lichtenbergstr. 4, 85747, Garching bei Mu¨nchen, Ger-
many. E-mail: rieger@tum.de; Fax: +49.89.289-13562; Tel: +49.89.289-
13571
bLehrstuhl fu¨r Anorganische Chemie mit Schwerpunkt Neue Materialien der
Technischen Universita¨t Mu¨nchen, Lichtenbergstr., 4, 85747, Garching bei
Mu¨nchen, Germany
Introduction of anionic functionalities by sulphonation, as
known for triphenylphosphine (TPP), is an efficient method
for facile ligand modification. The resulting ligands are for
example employed in biphasic hydroformylation with Rh-based
† Electronic supplementary information (ESI) available: NMR spectra for
synthesised compounds and representative GPC plots. CCDC reference
number 816463. For ESI and crystallographic data in CIF or other
electronic format see DOI: 10.1039/c1dt10372e
8304 | Dalton Trans., 2011, 40, 8304–8313
This journal is
The Royal Society of Chemistry 2011
©

tris-meta-sulphonated triphenylphosphine complexes (m,m,m-
tion products obtained under different conditions. Unambiguous
characterisation was achieved by multinuclear NMR spectroscopy
in combination with high resolution ESI–MS spectrometry.
2
TPPTS).29–33 A possible combination of k -(P,O)-coordinating
properties with the high negative charge density of mul-
tiply sulphonated ligands led us to the concept of non-
symmetrically sulphonated phosphines. Direct sulphonation of
2-(diphenylphosphine)benzenesulphonic acid 1 with fuming sul-
phuric acid was investigated, as double sulphonation of aryl
substituents was not observed in related reports.29
Product isolation and characterisation
Test reactions of the direct non-symmetric sulphonation of 1
showed the presence of several products, namely the sulphonated
phosphines 2b (rac-o,m-TPPDS), 2c (o,m,m-TPPTS) and phos-
phine oxides 3b–c together with a sulphone 4 as by products
(Scheme 2). At low SO3 concentrations and short reaction times
residual 2a (o-TPPMS, the salt of the starting product 1) could be
observed, in addition to the other sulphonation products.
Non-symmetric sulphonation of triphenylphosphine
Sulphonation of triarylphosphines proceeds in a two step pro-
cedure by reaction with SO3 in H2SO4 solution (Scheme 1).
The sulphuric acid permits the transformation by protonation
at phosphorus with the resulting phosphonium centre directing
sulphonation at the meta-position of the aryl rings and providing
protection towards oxidation with SO3.33–34 Therefore sulphonate
functionalities not located in the meta-position with respect to
phosphorus must be introduced in advance.
Scheme 1 Concept for the sulphonation of o-TPPMS 1.
Modification of the TPP sulphonation protocol as previously
detailed in the literature proved to be suitable for the sulphonation
of 1.34–35 The SO3 content is adjusted by the addition of fuming
sulphuric acid to a solution of 1 in concentrated sulphuric acid.
Hydrolysis, neutralisation with an alkali metal hydroxide and
extraction of the reaction products with methanol after removal
of H2O was chosen for the general work-up procedure. Specific
isolation of the components is detailed below. Similar to the
sulphonation of TPP the reaction conditions are modified to
control the selectivity of the reaction and influence the product
composition (Table 1). Key influence factors were identified as a)
reaction temperature; b) concentration of SO3; c) concentration of
H2SO4 and d) the ratio n(SO3) : n(phosphine). Reaction progress
was followed by 31P NMR spectroscopy after neutralisation of
aliquots after defined time intervals. Screening of the reaction
parameters permitted the isolation and identification of the reac-
Scheme 2 Overview of observed reaction products from sulphonation
of 1; sulphonated phosphines 2a–c, phosphine oxides 3b–c and cyclic
sulphone 4.
The employed reaction conditions are listed in Table 1 together
with a comparison of obtained sulphonation results which are also
displayed graphically in Fig. 2. Entries 2 and 3 show conditions
favouring the formation of 2b and 2c, respectively. Highly enriched
concentrations of the desired phosphines are required for their suc-
cessful isolation, due to the similar solubility of these sulphonated
phosphines and the corresponding phosphine oxides. Solubility
differences for the respective K+ and Na+ salts in water, methanol
and ethanol can be exploited for their isolation and purification.
The predominant formation of 2c (conditions: Table 1, Entry 2)
allowed fractional precipitation by the addition of ethanol and
Table 1 Reaction conditions employed in the screening of the sulphonation of 1 and composition of the obtained sulphonation mixturea
n(SO3)/
n(phosphine)
SO3
(% w/w)
H2SO4
(% w/w)
o-TPPMS
2a (%)b
rac-o,m-TPPDS
2b (%)b
o,m,m-TPPTS
2c (%)b
Sulphone
Oxides
Entry
t (h)
T/◦C
4 (%)b
3b–c (%)b
1
2
3
4
5
6
20
20
20
20
40
24
RT
30
30
30
30
50
10
6
12
35
35
16
19
28
30
49
49
19
74
55
61
45
45
76
0
2
0
0
0
0
43
75
6
0
0
57
19
78
50
18
6
0
1
10
21
58
9
0
3
5
30
24
85
0
a Control of the SO3 content and other parameters by combination of H2SO4 with fuming sulphuric acid (65 or 20% w/w). b Product mixture composition
given in mol% of the total phosphorus content determined by 31P NMR spectroscopy, graphical comparison in Fig. 2.
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©

Fig. 2 Composition of the product mixture in the non-symmetric
sulphonation of 1 at different reaction conditions (Table 1).
cooling to -25 ◦C due to the relatively high solubility of the
sodium salts. In advance minor impurities of 4 must be removed by
crystallisation from hot methanolic solution then cooling to 5 ◦C.
By contrast, due to the reduced solubility of the potassium salts
in methanol, 2b can be isolated from concentrated hot solutions
by fractionised crystallisation upon cooling to -25 ◦C as a fine
microcrystalline solid (conditions: Table 1, Entry 3). 2b and 2c
are both obtained as hydrates with a relatively low content of
by-products (90.0% and 84.0% of total phosphorus content as
determined by integration of their 31P NMR spectra, 2b and 2c,
respectively).34
Scheme 3 Intramolecular sulphonation of 1 to the sulphone 4 via a) a
phosphine intermediate or b) a dicationic phosphonium intermediate in
the formation of the electrophile with involvement of the acidic reaction
medium. Anions generated by reaction with H2SO4 omitted for clarity.
Table 2 Reference data for compounds 2b–c, 3b–c, 4
2b
2c
3b
3c
4
The formation of the oxide 3c (o,m,m-TPPTSO) is favoured at
longer reaction times (Entry 5) and higher temperatures (Entry 6),
as is known for the analogous formation of m,m,m-TPPTSO.29,35
3b could only be identified as a by product in low concentrations
under the conditions specified in Entry 2.
a
d (ppm)
-10.5
-10.3
38.7
38.0
8.9
m/zfound (M-)
458.9561 544.9198 474.9476 560.9167 418.9831
m/zcalculated (M-) 458.9528 544.9176 474.9477 560.9126 418.9813
Counterion
K
Na
K
Na
Na
a Chemical shift observed by 31P NMR spectroscopy, 121 MHz, D2O.
One surprising observation in this system is the formation of
a sulphone as a by-product. The generation of 4 appears to
be favoured by a high SO3 content in the sulphonation mixture
(Table 1, Entry 5) and originates from the ortho-sulphonate func-
tionality in 1. After SO3-promoted dehydration the sulphonate
can act as an electrophile which is capable of an intramolecular
cyclisation with a second, non-sulphonated aryl substituent at
phosphorus (Scheme 3). The limited available data on this
previously unprecedented reaction indicate the involvement of
activated ortho-directing intermediates and a strongly favoured
oxide formation. Protonation and dehydration of the sulphonate
functionality most likely lead to a phosphine intermediate (Scheme
3, Path a)) which is favoured over the alternative phosphonium
analogue, due to the close contact of positive charges (Scheme 3,
Path b)). Additionally Path a) is supported by the sulphonation
in the ortho-position which is disfavoured in deactivated aromatic
systems. Subsequent oxidation of the unprotected phosphorus(III)
centre leads to complete conversion to the corresponding P(V)
compound. The deactivating influence of the sulphonate func-
tionalities prevents double sulphonation on one aryl substituent.
Analysis by multinuclear NMR spectroscopy and high resolution
mass spectrometry unambiguously confirmed the structure of 4.
This by product, however, is readily removed from the reaction
mixture by crystallisation from methanol.29,33
alteration of the ratio of n(SO3) : n(phosphine). The obtained 31P
NMR spectroscopic reference shifts, together with the comparison
of high resolution ESI MS data, with calculated m/z values for all
identified reaction products are displayed in Table 2. The degree
of meta-sulphonation has only a minor influence on the position
of phosphine signals in 31P NMR spectra, as reported in literature
and no influence on the alkali metal ion could be observed.36
31P NMR spectroscopy was exploited to gain further insight
into the reaction sequence and rate at conditions under which the
selectivity of the reaction for 2b or 2c could be controlled. Small
aliquots of the reaction mixture were quenched with a cooled
5 M NaOH solution in D2O and the observed signals in the
respective 31P NMR spectra were assigned to the reaction products.
Integration allows the evaluation of the reaction progress under
these specific conditions.
Fig. 3 shows formation of the reaction products at a 12 : 1
ratio of SO3 : phosphine. Fast sulphonation of 1 to 2b results
in an apparent peak of the 2b concentration which is followed
by a slightly slower second sulphonation to 2c. Concentration
of the formed by products slowly increases with the reaction
time. Fig. 4 shows the reaction at the reduced ratio with 7 : 1
of SO3 : phosphine, which results in lowered reaction rates for the
sulphonation.
Screening of the reaction parameters as detailed above showed
optimal conditions for the isolation of 2b–c at 30 ◦C and ca. 30%
SO3. Selectivity for either 2b or 2c can easily be controlled by
Both diagrams confirm the consecutive reaction with relatively
fast sulphonation to 2b, followed by a slower reaction to 2c.
8306 | Dalton Trans., 2011, 40, 8304–8313
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Furthermore the strong dependence on the SO3 concentration
indicates a higher reaction order for the sulphonation, as expected.
Side product formation is initially relatively slow and increases
with long reaction times.
Phase transfer and complex synthesis
Polymerisation of olefins and synthesis of suitable catalyst pre-
cursors usually requires solubility of employed ligands and their
respective complexes in organic solvents. However, the synthesised
ligand salts 2b,c are soluble only in water or methanol, which is
therefore also expected for derived complex salts. Phase transfer
reactions can ensure solubility of ligands and their resulting
complexes in polar organic solvents such as methylene chloride.
Similar reactions are already reported in the literature, for example
the use of alkylammonium salts for the isolation of m,m,m-TPPTS
by reactive extraction32 as well as phase mediators for catalytic
reactions with complexes based on this ligand37–39 Additionally
synthesis of monoanionic phosphine sulphonate Pd(II) complexes8
or the complexation of alkali metals as cryptand salts40 are
described. A suitable Pd(II)-containing precursor for the synthesis
of polymerisation catalysts is (COD)PdMeCl8,41 (COD = 1,5
cyclooctadiene) which does not require highly Lewis acidic and
alkylating alkylaluminium compounds as activators. The latter
are not compatible with the present Pd(II)-based sulphonate
salts.
Fig. 3 31P NMR spectroscopic kinetic investigation for the sulphonation
of 1. Reaction conditions: 30% (w/w) SO3, n(SO3) : n(phosphine) = 12, 61%
(w/w) H2SO4, sample work up by reaction with 5 M NaOH in deuterium
oxide.
Phase transfer reactions of 2b and 2c were performed by alkali
metal ion exchange with NBu4Cl in degassed water, followed
by extraction with methylene chloride (Scheme 4).39 Subsequent
2
complexation with (COD)PdMeCl affords the respective k -
(P,O)-chelated complexes. Unfortunately crystallisation of the
compounds to remove residual by-products was not achieved and
therefore complete characterisation was not possible, a situation
which is attributed to the flexible dynamic behaviour of the tetra-
butylammonium cations. Confirmation of the complex formation
is derived from the 31P NMR spectroscopic shift of the phosphorus
upon coordination (by comparison to the free phosphine) and the
Fig. 4 31P NMR spectroscopic kinetic investigation for the sulphonation
of 1. Reaction conditions: 31% (w/w) SO3, n(SO3) : n(phosphine) = 7, 54%
(w/w) H2SO4, sample work up by reaction with 5 M NaOH in deuterium
oxide.
Scheme 4 Phase transfer of 2b and synthesis of the respective Pd-based precatalysts; a) K+ complexation by crown ethers and reaction to 6, b) ion
exchange with alkylammonium salts, see footnote‡.
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©

characteristic cis-3J(P-CH3) coupling constants with respect to
the phosphorus atom.42,
‡
However, the reaction of 2b as the potassium salt with 18-crown-
6 in methylene chloride solution provided 5b (Scheme 4) with a
slight excess of crown ether (2.4 equivalents). In the following
ligand exchange reaction with (COD)PdMeCl the dianionic
chiral phosphine sulphonate based Pd(II) pre-catalyst 6 with
[K(18-crown-6)]+ counterions was obtained in good yields after
crystallisation.8 Attempts to modify the polarity of the formed
crown ether coordinated salts by introduction of dibenzo-18-
crown-6 were unsuccessful, presumably due to solubility problems
in the synthesis of the respective crown ether complex from 2b
in toluene or methylene chloride. As a consequence of the non-
symmetric substitution pattern with three different substituents
present at the phosphorus, 2b and its derived compounds are chiral
and obtained as racemic mixtures.
Single crystals of 6 suitable for analysis by X-ray diffractometry
were obtained from methylene chloride–pentane mixtures in the
absence of light. The molecular structure of 6 (Fig. 5) shows
2
k -(P,O)-chelated near square planar coordination of the ligand
Fig. 5 ORTEP plot of compound 6, hydrogen atoms and the atoms of
the second orientation for the disordered crown ether molecule have been
omitted for clarity, no labels for the crown ether atoms and the carbon
atoms beside C(1) are displayed. Thermal ellipsoids are drawn at the 50%
probability level. Both crown ether units were refined isotropically and the
two conformations for the [K(2)(18-crown-6)]+-crown ether refined wi◦th
to the palladium centre. In addition to a well-resolved complex
backbone strongly disordered cations are observed. Both [K(18-
crown-6)]+ ions of the dianionic complex 6 are located at the meta-
sulphonate functionality, most likely due to molecular packing in
the solid state. Selected bond lengths of the complex backbone are
listed in the caption of Fig. 5. The problematic characterisation
of sulphonated complex salts by single crystal X-ray diffraction
results in very limited structural data28,40,43–46 for comparison with
related compounds.§ All other obtained analytical data fully
support the observed molecular structure of 6.
˚
a ratio of 0.769(6) : 0.231(6). Selected bond lengths [A] and angles [ ]:
Pd(1)–C(1) 2.0193(4), Pd(1)–Cl 2.387(3), Pd(1)–O(1) 2.184(5), Pd(1)–P
2.220(2), Pd(1) ◊ ◊ ◊ O(2) 3.371(6), K(1) ◊ ◊ ◊ O(4) 2.874(6), K(1) ◊ ◊ ◊ O(5)
2.820(7), K(2) ◊ ◊ ◊ O(6) 2.597(7), average K–O(crown ether) distance
2.83; C(1)–Pd(1)–P 88.74(5), C(1)–Pd(1)–O(3) 175.9(2), C(1)–Pd(1)–Cl
90.25(5), P–Pd(1)–O(3) 95.2(2), P–Pd(1)–Cl 177.68(7).
The non-meta sulphonated complex 7 was synthesised as a
reference catalyst precursor8 from 1 by subsequent reaction with
KOH and 18-crown-6 to 5a, followed by ligand exchange with
(COD)PdMeCl (Scheme 5). Crystallisation was carried out in
2
an analogous manner to 6. As all obtained k -(P,O)[phosphine
sulphonate]PdMeCl complexes are light sensitive all reactions are
carried out in absence of light and the resulting compounds are
stored at -20 ◦C under an inert atmosphere.
Scheme 5 Synthesis of 7 as reference catalyst precursor from 1.
suitable for in situ activation by abstraction of the chloro-ligand
with silver salts (e.g. AgSbF6, Scheme 6).
Polymerisation reactions
Homopolymerisation reactions with ethene showed that 6 and
the related catalyst 7 are active polymerisation catalyst precursors
Table 3 lists the obtained ethene homopolymerisation data. 6
shows a significantly reduced activity compared to the reference
catalyst 7, which is also several orders of magnitude lower than
the most active phosphine sulphonate-based palladium catalysts.6
Bimodal broad molecular weight distributions for linear PE
obtained with 6 indicate aggregation of the catalyst in toluene.
Similar observations have been previously reported for related Ni-
and Pd-based catalysts.28,47
Peak separation in GPC elugrams could be enhanced by
viscometer and light scattering detectors, which are more sensitive
towards high molecular weight fractions. Compared to the RI
detection traces the bimodal character was more pronounced.
Entries 7 to 9 in Table 3 show that the molecular weights of the
fraction with high Mw decrease, as expected, with increasing reac-
tion temperature. In contrast the Mw for the low molecular weight
fraction is independent of temperature. The presence of the highly
polar ionic liquid 1-ethyl-3-methyl-imidazolium tetrafluoroborate
in a comparative experiment (Entry 11) prevents aggregation and
‡ Summary of relevant analytical data for the respective ammonium
salts of 2b and c, which could not be crystallised:[NBu4]2[rac-o,m-
TPPDS]: 31P NMR (121 MHz, CD2Cl2) d -9.7.[NBu4]2[k (P,O){rac-o,m-
2
TPPDS}PdMeCl]: 1H NMR (300 MHz, CD2Cl2) d 0.48 (d, 3J(P-CH3) =
3.4 Hz, Pd-CH3). 31P NMR (121 MHz, CD2Cl2) d +26.7. [NBu4]3[o,m,m-
TPPTS]: 31P NMR (121 MHz, CD2Cl2) d -9.8.[NBu4]3[k (P,O){o,m,m-
2
TPPTS}PdMeCl]: 1H NMR (300 MHz, CD2Cl2) d 0.46 (d, 3J(P-CH3) =
3.4 Hz, Pd-CH3). 31P NMR (121 MHz, CD2Cl2) d +27.0 (s).
§ In contrast to their relatively common application in homogeneous
catalysis, molecular structures of complexes with di- and tri-sulphonated
phosphines are rare in the literature, as formation of long range order
for crystallisation is dependent on the nature of cations and possible
packing. One known approach to crystallise respective complexes is the
complexation of cations. Otherwise strong cation–sulphonate interactions
can lead to formation of complex bridged networks between molecules. In
addition to the five known structures m,m,m-TPPTS based complexes only
the tetrameric di-ortho-sulphonated TPP based complex mentioned above
and the here reported complex 6 exist for triphenylphosphine complexes
with a higher degree of sulphonation (>1).
8308 | Dalton Trans., 2011, 40, 8304–8313
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Scheme 6 General procedure for polymerisation reactions after salt abstraction with anionic phosphine sulphonate-based Pd(II) catalyst precursors.
Table 3 Polymerisation data for the ethene homopolymerisation with compounds 6 and 7a
Entry
7
Cat.
6
T/◦C
50
p (bar)
20
t (h)
20
20
20
20
20
20
2
Yield (g)
0.58
Activityc
1.4
Mw (high)d
Mw (low)d
PDI (high)e
PDI (low)e
Tm (◦C)f
588 (M)
520 (R)
360 (M)
370 (R)
285 (M)
300 (R)
284 (M)
310 (R)
n.o.
n.d.
7.1 (M)
8.9 (R)
7.1 (M)
5.7 (R)
6.0 (M)
5.1 (R)
6.4 (M)
5.7 (R)
n.o.
n.d.
119
129
126
2.6 (R)
3.0 (M)
3.0 (R)
2.4 (M)
2.7 (R)
3.0 (M)
3.0 (R)
3.4 (M)
4.0 (R)
5.0 (M)
5.4 (R)
4.8 (M)
5.5 (R)
2.0 (R)
1.4 (M)
4.6 (R)
2.3 (M)
2.4 (R)
1.6 (M)
2.7 (R)
3.1 (M)
3.9 (R)
3.7 (M)
4.9 (R)
5.3 (M)
5.8 (R)
8
6
80
20
2.44
5.7
9
6
100
80
20
2.86
6.7
125
125
123
119
122
10
11b
12
13
6
10
1.27
6.0
6
100
100
100
20
0.25
0.6
7
20
4.60
10.8
22.2
n.o.
n.o.
n.o.
n.o.
7
20
0.95
a 200 mL stainless steel reactor, 10 mmol catalyst, 1.1 equivalents AgSbF6, 30 mL toluene; b Additive 1-ethyl-3-methyl-imidazolium tetrafluoroborate
-1
-1
(2 mL), 100 mL autoclave, 10 mL toluene; c Activity gpolymer gpalladium barethene h-1; d 103 g mol-1 (high and low molecular weight fraction), (M) = multi
detection (RI, viscometer, light scattering), (R) = RI detection; e PDI = Mw/Mn, (R) and (M) detection; f Determined by DSC; n.d. = not determined,
n.o. = not observed.
leads selectively to formation of low Mw polyethylene with reduced
catalyst activity. Ethene homopolymerisation with the bis-phenyl
substituted reference catalyst 7 (Entries 12 and 13) exclusively
produced low Mw PE. These observations support the assumption
that the low molecular weight polymer is formed at catalyst sites
with minor influence of aggregation.
higher MA concentrations and high reaction temperatures catalyst
stability proved to be problematic and therefore resulted in radical
homopolymerisation of MA.
Copolymerisation of AN with ethene under the conditions
specified in literature led to the formation of linear low molecular
weight copolymers. Monomodal molecular weight distributions
show that copolymerization takes place without PE formation,
probably due to the stabilising coordinating effect of the AN
monomer at high concentration and higher temperature. As-
signment of relevant peaks to appropriate structural motives by
high temperature 1H NMR spectroscopy, according to published
reference data, show an incorporation ratio of 4.5 mol % without
radical AN polymerisation.8 End group analysis confirms 2,1-
insertion of AN into a Pd–H bond, as well as E- and Z-isomers of
nitrile terminated olefin end groups originating from b-hydride
elimination after AN insertion. Additionally AN units in the
polymer backbone could be identified, giving a total ratio of 1 : 1 : 1
initial/internal/terminal-AN-containing units. Comparison with
literature known copolymers also shows an increased content of
vinylic olefin end-groups with a previously unprecedented low
content of internal olefins. These observations indicate a reduced
To evaluate the effect of the introduced negative charge density
on the ligand backbone copolymerisation experiments with 6 in
the presence of methyl acrylate (MA), acrylonitrile (AN) and
vinyl acetate (VA) were performed. Comparison of the obtained
results listed in Table 4 with literature data shows only reduced
incorporation ratios for polar functionalised olefins.8,12,14 GPC
elugrams show a bimodal molecular weight distribution for all
copolymers except those containing AN. This indicates a non-
uniform polymerisation mechanism, which is confirmed by the
sharp distinct melting points for the linear PE homopolymer in
the DSC plots. However high temperature 1H NMR spectroscopy
of the polymerisation products confirms low MA incorporation.
These observations indicate that at the applied polymerisation
conditions aggregation of 6 could not be reversed and high
molecular weight PE is partially formed. In the presence of
This journal is
The Royal Society of Chemistry 2011
Dalton Trans., 2011, 40, 8304–8313 | 8309
©

Table 4 Copolymerisation reactions of ethene and polar functionalised monomers with compound 6a
Entryc
14b
T/◦C
80
pEthen
20
X, cx (M L-1)e
MA, 1.5
Yield (mg)
390
% xPol
5.8
Mw
PDIg
Mp
f
g
h
559
7.0
318
3.9
1.1
310
4.0
379
3.1
3.3
3.9
5.5
2.3
1.7
5.3
2.5
7.4
3.2
135i
132i
15b
80
10
MA, 1.5
108
8.0
16c
17d
100
80
30
20
AN, 7.5
VA, 1.1
225
90
4.5
—
109j
131i
18d
80
20
VA, 2.7
105
—
n.d.
a 100 mL stainless steel reactor, 10 mmol catalyst, 1.1 equivalents AgSbF6; b 15 mL total solution of toluene and MA, 20h; c 200 mL stainless steel autoclave
5 mL AN, 5 mL toluene, 120 h; d 20 mL total solution of VA and toluene, 20 h; e comonomer with concentration; f from HT 1H NMR spectroscopy at
110–120 ◦C; g 103 g mol-1 GPC at 160 ◦C, bimodal molecular weight distributions observed as for PE homopolymers, only multi detection displayed,
entry 16 monomodal distribution, h determined by DSC, i Tm of linear PE dominates the DSC plots, j broadened towards lower temperatures, n.d. = not
determined.
coordination and insertion of AN in the present catalyst system.
In contrast to the successful ethene/AN copolymerisation similar
experiments in presence of VA led to formation of PE without
VA incorporation. GPC analysis showed the presence of bimodal
molecular weight distributions similar to those of the previously
described PE homopolymerisation reactions.
In general the low catalyst activity and aggregation indicate
decreased coordination strength of the olefin monomers. This
is expected due to the higher electron density near the metal
centre which increases across the series cationic (early transition
metal) < cationic (late transition metal) < neutral < anionic.48
Only a few cases of active anionic polymerisation catalysts exist
which often show lowered activities compared to their neutral or
cationic parent systems.28,49 A positive effect on the incorporation
of polar functionalised olefins similar to the ethene/vinyl fluoride
copolymerisation in the related anionic phosphine sulphonate
catalyst system described above could not be observed.16,28
highly polar ligands which show high water solubility could be
of significant interest for homogeneous catalysis by application in
other systems.
Experimental
General considerations
All reactions were routinely carried out under argon using stan-
dard Schlenk techniques or in a glovebox unless otherwise stated.
Chemicals were obtained from Sigma Aldrich, Acros Organics
or ABCR and used as received without further purification
unless stated otherwise. Dry solvents were obtained from a
MBraun MB-SPS-800 solvent purification system and all other
solvents were degassed prior to use. Benzenesulphonic acid was
dried by azeotropic distillation with toluene and 18-crown-6 was
sublimed under vacuum before use. All palladium compounds
were stored under exclusion of light at -20 ◦C in a glovebox fridge.
(COD)PdMeCl50 and 2-(diphenylphosphino)benzene-sulphonic
acid 151 were prepared according to literature procedures.
Solution NMR spectra were collected at room temperature
using a Bruker ARX300 or AV500 spectrometer. High temperature
solution NMR spectra were recorded at 100 to 130 ◦C in C2D2Cl4.
1H and 13C NMR spectra are referenced to the residual solvent
peak of SiMe4 or in case of 31P NMR spectra to 85% phosphorus
acid as external standard. Polymer samples were filtered at
160 ◦C before GPC on a Polymer Laboratories PL-GPC 220
high temperature chromatograph, equipped with 2 Olexis 300 ¥
7.5 mm columns and triple detection by a differential refractive
index detector, a PL-BV 400 HT Viscometer and a Precision
Detectors Model 2040 Light Scattering Detector (15◦, 90◦). The
solvent was 1,2,4-trichlorobenzene (BHT stabilized) at 160 ◦C,
with a PE standard. DSC was measured on a TA Instruments DSC
Q2000 calorimeter at a heat/cooling rate of 10 K min-1. Elemental
analyses were performed by the micro analytical laboratory of
the department of Inorganic Chemistry at Technische Universita¨t
Mu¨nchen. Characterisation of compounds obtained as hydrates
is supported by high resolution ESI-MS spectra, obtained on a
Bruker micrOTOF-Q, calibrated against sodium formiate 5 mmol
L-1 with 0.2% (v/v) formic acid in a water–isopropanol 1 : 1
mixture.
Conclusions
Direct sulphonation of 1 was shown to be a viable con-
cept for the synthesis of new non-symmetrically functionalised
triphenylphosphine-based water soluble ligands. The possibility
2
of k -(P,O)-chelating coordination for derived Pd(II) complexes
was shown. Controlled synthesis with organometallic complex
precursors in polar organic solvents was possible after phase
transfer reactions, which are carried out preferentially by cation
complexation with crown ethers. This concept allowed the de-
velopment of a novel anionic phosphine sulphonate Pd(II)-based
pre-catalyst salt 6 for polymerisation reactions. Ethene homopoly-
merisation leads to formation of PE with a bimodal molecular
weight distribution, which can be attributed to aggregation of the
catalyst in toluene as the reaction medium. Due to electronic or
steric effects polymerisation activities are significantly reduced,
compared to related neutral catalysts. The anticipated facilitated
monomer p-coordination, resulting in increased incorporation
of polar functionalised comonomers was not observed. Poly-
merisation in presence of methyl acrylate, acrylonitrile and vinyl
acetate only led to reduced incorporation values compared to the
available literature reports in combination with problems that are
attributed to aggregation of the catalyst in most cases. Despite
the low polymerisation activity, the facile synthesis of chelating
8310 | Dalton Trans., 2011, 40, 8304–8313
This journal is
The Royal Society of Chemistry 2011
©

General procedure for the sulphonation reaction
544.9198 (M - Na+). Anal. calc. for C18H12Na3O9PS3: C 38.03, H
2.13, S 16.92. Found: C 35.54, H 2.46, S 13.19.
1 was dissolved by portion-wise addition to concentrated sulphuric
acid. The desired reaction conditions were adjusted by addition
of fuming sulphuric acid (20% or 65% (w/w) SO3) under vigorous
agitation while maintaining cooling of the reaction vessel. The
reaction mixture was then heated to 30 ◦C and stirred for
the desired reaction time. Termination was achieved by careful
addition of degassed water at -10 to 0 ◦C. Neutralisation was
carried out by addition of an aqueous alkali metal solution
(5 M) to pH ~9. The majority of the water was removed under
reduced pressure and the reaction products were extracted from
inorganic salt residues by refluxing with MeOH. Filtration of the
hot mixture, complete removal of volatiles and redissolving in dry
methanol provides the mother solution for subsequent isolation
of reaction products.
10-(3-Sulphonatophenyl)-10H-9-thia-10-phosphaanthracene-
9,9,10-trioxide 4, sodium salt
Specific conditions: Sulphonation of 1 (5.00 g, 14.6 mmol), 7 mL
concentrated sulphuric acid (95–97%), 33 mL◦fuming sulphuric
acid (65% SO3 (w/w)), reaction over 40 h, 30 C, neutralisation
with NaOHaq (5 M). 4 was obtained by crystallisation upon cooling
of the hot mother solution to 5 ◦C (2.15 g) as the hydrate with
included MeOH.
n(SO3) : n(phosphine) 35 : 1, SO3 49% w/w, H2SO4 45% w/w.
1H NMR (500 MHz, D2O) d 8.17 (m, 2H), 8.05–8.01 (m, 2H),
7.98 (m, 2H), 7.91 (m, 2H), 7.76 (m, 2H), 7.67 (m, 2H), 7.57–7.48
1
(m, 2H). 13C{ H} NMR (75 MHz, D2O) d 144.7 (d, J (C-P) = 13.6
Hz), 141.3 (d, J (C-P) = 7.6 Hz), 135.3 (s), 135.2 (d, J (C-P) = 11.5
Hz), 134.8 (d, J (C-P) = 11.9 Hz), 134.0 (d, J (C-P) = 4.9 Hz), 132.2
(d, J (C-P) = 113.7 Hz), 131.5 (s), 130.9 (d, J (C-P) = 13.5 Hz),
129.1 (d, J (C-P) = 12.8 Hz), 128.9 (d, J (C-P) = 102.0 Hz), 126.3
rac-o,m-Triphenylphosphine disulphonate (rac-o,m-TPPDS) 2b,
potassium salt
Specific conditions: Sulphonation of 1 (10.0 g), 10 mL concen-
trated sulphuric acid (95–97%), 13 mL fuming sulphuric acid (65%
(w/w) SO3), reaction over 20 h, 30 ◦C, neutralisation with KOHaq
(5 M). Fractional crystallisatio◦n of the hot mother solution in
methanol upon cooling to -25 C provided 2b (9.43 g, 90.0% of
total P content) as the hydrate.
1
(d, J (C-P) = 7.5 Hz). 31P{ H} NMR (121 MHz, D2O) d +8.9 (s).
HRMS (ESI-, H2O) Calc. for C18H12O6PS2: m/z = 418.9813 (M-).
Found: m/z = 418.9831 (M - Na+). Anal. calc. for C18H12O6NaPS2:
C 48.87, H 2.73, S 14.50, P 7.00, Na 5.20. Found: C 47.34, H 3.38,
S 13.56, P 6.30, Na 5.20.
n(SO3) : n(phosphine) 6 : 1, SO3 28% w/w, H2SO4 55% w/w.
1H NMR (500 MHz, D2O) d 8.06 (m, 1H), 7.82 (m, 1H), 7.70
(m, 1H), 7.51 (m, 1H), 7.41 (m, 2H), 7.37–7.29 (m, 3H), 7.26 (m,
Kinetic investigation of the sulphonation reaction
Fig. 3: Sulphonation of 1 (2.00 g), 7 mL concentrated sulphuric
acid (95–97%), 4 mL fuming sulphuric acid (65% SO3 (w/w)),
reaction over 6 h, 30 ◦C. A reference sample was taken before
addition of fuming sulphuric acid, followed by repeated sampling
at defined time intervals. Termination by addition of 5 M NaOH
in ice cooled deuterium oxide for determination of the product
composition by 31P NMR spectroscopy. Relative peak positions
assignedandquantified. Conversionofallproductsplottedagainst
reaction time.
n(SO3) : n(phosphine) 12 : 1, SO3 30% w/w, H2SO4 61% w/w.
Fig. 4: See above, 1 (2.00 g), 4 mL concentrated sulphuric acid
(95–97%), 3 mL fuming sulphuric acid (65% (w/w) SO3) over 6 h,
30 ◦C.
1
3H), 7.04 (m, 1H). 13C{ H} NMR (75 MHz, D2O) d 148.2 (d,
J(C-P) = 26.2 Hz), 143.7 (d, J (C-P) = 6.4 Hz), 139.6 (d, J (C-P) =
12.8 Hz), 137.1 (d, J (C-P) = 10.3 Hz), 137.0 (d, J (C-P) = 7.9 Hz),
136.9 (s), 134.7 (s), 134.5 (d, J (C-P) = 21.8 Hz), 134.4 (s), 132.3
(s), 131.0 (s), 130.8 (s), 130.7 (s), 130.2 (s), 130.2 (d, J (C-P) = 5.9
Hz), 129.8 (d, J (C-P) = 7.0 Hz), 128.3 (d, J (C-P) = 4.7 Hz), 126.7
(s). 31P NMR (121 MHz, D2O) d -10.5. HRMS (ESI-, H2O) Calc.
for C18H13KO6PS2: m/z = 458.9528 (M-). Found: m/z = 458.9561
(M - K+). Anal. calc. for C18H13K2O6PS2: C 43.36, H 2.63, S 12.86.
Found: C 42.32, H 2.79, S 11.34.
o,m,m-Triphenylphosphine trisulphonate (o,m,m-TPPTS) 2c,
n(SO3) : n(phosphine) 7 : 1, SO3 31% (w/w), H2SO4 54% (w/w).
sodium salt
Specific conditions: Sulphonation of 1 (5.00 g), 10 mL concen-
trated sulphuric acid (95–97%), 13 mL fuming sulphuric acid (65%
(w/w) SO3), reaction over 20 h, 30 ◦C, neutralisation with NaOHaq
(5 M). Impurities of 4 were separated by crystallisation from the
hot mother solution upon cooling to 5 ◦C. Fractional precipitation
with ethanol provided 2c (5.35 g, 84.0% of total P content) as the
hydrate.
[K(18-crown-6)][o-TPPMS] 5a
1 (3.42 g, 10 mmol) was suspended in water (15 mL) and KOHaq.
(0.56 g, 0.1 g mL-1, 10 mmol) was added. The solvent was removed
under vacuum and the potassium salt 2a was recrystallised from
methanol (2.90 g, 7.62 mmol). 2a (2.44 g, 6.41 mmol) and 18-
crown-6 (1.69 g, 6.41 mmol) were suspended in methylene chloride
(35 mL) and stirred for 15 h. After filtration (Whatman glass
microfiber filter, 1.0 mm) the product was obtained as a white
powder (4.26 g, 6.35 mmol). 1H NMR (300 MHz, CD2Cl2) d 8.11
n(SO3) : n(phosphine) 12 : 1, SO3 30% w/w, H2SO4 60% w/w.
1H NMR (500 MHz, D2O) d 8.09 (m, 1H), 7.89–7.85 (m, 2H),
7.73–7.69 (m, 2H), 7.61 (m, 1H), 7.55 (m, 2H), 7.49–7.42 (m, 3H),
1
1
7.14 (m, 1H). 13C{ H} NMR (75 MHz, D2O) d 148.1 (d, J (C-P) =
(m, 1H), 7.42–7.15 (m, 12H), 7.04 (m, 1H), 3.56 (s, 27H). 13C{ H}
26.5 Hz), 143.7 (d, J (C-P) = 6.4 Hz), 138.8 (d, J (C-P) = 13.0 Hz),
137.3 (d, J (C-P) = 19.2 Hz), 137.1 (d, J (C-P) = 1.3 Hz), 133.7 (d,
J (C-P) = 21.7 Hz), 132.5 (s), 131.0 (d, J (C-P) = 2.6 Hz), 130.8 (s),
130.3 (d, J (C-P) = 6.2 Hz), 128.3 (d, J (C-P) = 4.9 Hz), 127.0 (s).
NMR (75 MHz, CD2Cl2) d 152.7 (d, J (C-P) = 27.1 Hz), 139.9 (d,
J (C-P) = 14.5 Hz), 135.9 (d, J (C-P) = 2.4 Hz), 135.0 (d, J (C-P) =
23.2 Hz), 134.2 (s), 133.9 (s), 129.4 (s), 128.9 (s), 128.5 (d, J = 6.1
Hz), 128.3 (s), 128.0 (d, J (C-P) = 5.1 Hz), 70.5 (s). 31P{ H} NMR
1
1
31P{ H} NMR (121 MHz, D2O) d -10.3 (s). HRMS (ESI-, H2O)
(121 MHz, CD2Cl2) d -9.0 (s). Anal. calc. for C30H38KO9PS: C
Calc. for C18H12Na2O9PS3: m/z = 544.9176 (M-). Found: m/z =
55.89, H 5.94, S 4.97. Found: C 54.55, H 6.02, S 4.45.
This journal is
The Royal Society of Chemistry 2011
Dalton Trans., 2011, 40, 8304–8313 | 8311
©

[K(18-crown-6)]2[rac-o,m-TPPDS] 5b
-2.5 (s). 31P NMR (121 MHz, CD2Cl2) d +26.6. Anal. calc. for
C31H41KO9PPdClS: C 46.44, H 5.15, S 4.00. Found: C 46.13, H
5.12, S 3.60.
2b was dried at 120 ◦C under vacuum and weighed (1.50 g,
3.01 mmol), 18-crown-6 was added (1.59 g, 6.02 mmol) and
suspended in methylene chloride (50 mL). After reaction for 18 h,
filtration (Whatman glass microfiber filter, 1.0 mm) and removal
of the solvent the product (2.89 g, 2.55 mmol, 0,4 eq. additional
coordinated 18-crown-6, Mwcorrected = 1132.95 g mol-1, 84.7% of
P content) was obtained as a white powder. No crystallisation
possible.1H NMR (300 MHz, CD2Cl2) d 8.09 (m, 1H), 7.95 (m,
1H), 7.76 (m, 1H), 7.35–7.15 (m, 8H), 7.10–7.03 (m, 2H), 3.53 (s,
General procedure of a polymerisation reaction
The catalyst and activator were added to a stainless steel re-
actor (100 or 200 mL) under argon, solvent and if necessary
comonomers were added. The reactor was sealed and ethene
pressure was applied. After reaction the polymerisation was
stopped by cooling with ice and venting of the reactor. Polymers
were obtained by precipitation in methanol, filtration and drying
at 80 ◦C in a vacuum drying oven.
57H). 13C NMR (75 MHz, CD2Cl2) d 152.8 (d, J (C-P) = 27.3
1
3
Hz), 147.7 (d, J (C-P) = 7.9 Hz), 139.9 (d, J (C-P) = 14.2 Hz),
139.5 (d, J (C-P) = 16.7 Hz), 136.1 (d, J (C-P) = 2.5 Hz), 135.0
(d, J (C-P) = 23.5 Hz), 134.6 (d, J (C-P) = 11.7 Hz), 134.0 (d, J
(C-P) = 19.4 Hz), 131.7 (d, J (C-P) = 29.2 Hz), 129.4 (s), 128.8
(s), 128.4 (d, J (C-P) = 6.1 Hz), 128.2 (s), 128.1 (d, J (C-P) = 3.6
Crystal structure determination
Single crystal X-ray diffraction data of crystals of compound 6
were collected at 110(2) K on a Bruker APEX II diffractometer
equipped with a rotating anode FR 591 (Mo-Ka radiation,
Montel mirror optics) and a CCD detector. Crystal data:
PdPClK2S2C43O18H64, M = 1184.10, triclinic, a = 10.4999(9),
b = 16.624(1), c = 16.890(1); a = 83.955(4), b = 78.587(4), g =
1
Hz), 128.0 (d, J (C-P) = 6.1 Hz), 126.4 (s), 70.4 (s). 31P{ H} NMR
(121 MHz, CD2Cl2) d -9.3 (s). Anal. calc. for C42H61K2O18PS2: C
49.11, H 5.99, S 6.24. Found: C 48.14, H 6.21, S 5.02.
[K(18-crown-6)]2[j2(P,O){rac-o,m-TPPDS}PdMeCl] 6
-1
¯
79.133(4), V = 2831.0(5), space group:P1, Z = 2, m = 0.687 mm ,
5b (1.72 g, Mwcorrected = 1132.95 g mol-1, 1.52 mmol) and
(COD)PdMeCl (398 mg, 1.50 mmol) were dissolved in methylene
chloride (15 mL) and the reaction stirred for 17 h under absence of
light. Volatiles were removed under vacuum and the solid residue
was washed with 2¥ 10 mL pentane. The product was recrystallised
twice from methylene chloride by overlaying with pentane (1 : 3).
Filtration and drying provided 6 as a colourless powder (1.42 g,
1.20 mmol, 80.0%). 1H NMR (500 MHz, CD2Cl2) d 8.07 (m, 1H),
8.03 (m, 1H), 7.94 (m, 1H), 7.64 (m, 2H), 7.46 (m, 2H), 7.36 (m,
5H), 7.06 (m, 1H), 3.54 (s, 48H), 0.53 (d, 3J (H-P) = 3.2 Hz, 3H).
13C NMR (75 MHz, CD2Cl2) d 150.1 (d, J (C-P) = 14.0 Hz), 148.4
(d, J (C-P) = 10.5 Hz), 135.6 (d, J (C-P) = 1.5 Hz), 135.5 (s),
135.4 (d, J (C-P) = 11.9 Hz), 135.4–135.2 (m), 132.0–131.5 (m),
131.3 (d, J (C-P) = 13.4 Hz), 131.3–130.8 (m), 131.0 (d, J (C-P) =
2.6 Hz), 130.8 (d, J (C-P) = 2.1 Hz), 130.7–129.8 (m), 130.2 (d,
J (C-P) = 6.4 Hz), 129.0–128.9 (m), 128.9–128.8 (m), 128.4–128.3
(m), 128.2 (d, J (C-P) = 3.6 Hz). 31P NMR (121 MHz, CD2Cl2) d
+27.4. Anal. calc. for C43H64K2O18PPdS2: C 43.62, H 5.45, S 5.42.
Anal. calc. for 6·0.5DCM: 42.59 H 5.34 S 5.23. Found: C 42.55,
H 5.61, S 5.14.
11707 reflections measured, 7210 unique (Rint0.0709), final R-
values: R1 = 0.1088, wR2 = 0.2304, all data R1 = 0.1469, wR2 =
0.2383.
The structure of the compound were solved using Direct
Methods in SHELX52 and refined on F2 using Jana200653 For
one of the crown ether molecules a second orientation could be
detected but disorder hindered a free refinement. It was therefore
refined with two orientations of a rigid body with the angles (H, U,
W) and a translational vector along the crystallographic axes. The
atomic positions of the main crown ether orientation were taken
from the structure solution and were used to define the rigid body.
The ratio of the two orientations refined to 0.769(6) : 0.231(6). The
atoms of both crown ether molecules were refined isotropically
and the displacement parameters of the crown ether with two
positions were refined as one. All other non-hydrogen atoms
were refined anisotropically. Due to heavy disorder of the solvent
molecules in the voids their contribution to the structure factors
were modelled using the “SQUEEZE” program in PLATON.54
The positions of the hydrogen atoms were calculated using a riding
model.
[K(18-crown-6)][j2(P,O){o-TPPMS}PdMeCl] 7
Abbreviations
5a (1.29 g, 2.00 mmol) and (COD)PdMeCl (530 mg, 2.00 mmol)
were dissolved in methylene chloride (20 mL) and the reaction
stirred for 12 h under absence of light. After removal of volatiles the
solid residue was washed with 2 ¥ 10 mL pentane and recrystallised
from methylene chloride by overlaying with pentane (1 : 3). After
filtration and drying under vacuum the product was obtained
AN
acrylonitrile
1,5-cyclooctadiene
COD
DFT
DSC
GPC
MA
Mn
Mw
PDI
PE
RI
density functional theory
differential scanning calorimetry
gel permeation chromatography
methyl acrylate
number average molecular weight
weight average molecular weight
polydispersity (Mw/Mn)
polyethylene
refractive index
triphenylphosphine
triphenylphosphine monosulphonate
triphenylphosphine disulphonate
1
as a colourless powder (1.17 g, 1.46 mmol, 73.0%). H NMR
(300 MHz, CD2Cl2) d 8.00 (m, 1H), 7.55–7.18 (m, 12H), 6.91 (m,
3
1H), 3.47 (s, 24H), 0.44 (d, J (H-P) = 3.4 Hz, 3H). 13C NMR
(75 MHz, CD2Cl2) d 150.1 (d, J (C-P) = 14.0 Hz), 135.3 (d, J
(C-P) = 1.4 Hz), 134.9 (d, J (C-P) = 12.5 Hz), 131.6 (d, J (C-P) =
52.5 Hz), 130.9 (d, J (C-P) = 2.4 Hz), 130.8 (d, J (C-P) = 2.1
Hz), 130.4 (d, J (C-P) = 41.0 Hz), 130.0 (d, J (C-P) = 6.3 Hz),
128.8 (d, J (C-P) = 11.0 Hz), 128.3 (d, J (C-P) = 7.5 Hz), 70.5 (s),
TPP
TPPMS
TPPDS
8312 | Dalton Trans., 2011, 40, 8304–8313
This journal is
The Royal Society of Chemistry 2011
©

TPPTS
TPPTSO
VA
triphenylphosphine trisulphonate
triphenylphosphineoxide trisulphonate
vinyl acetate
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We thank S. Kaviani-Nejad and Prof. Dr P. Ko¨hler of the Deutsche
Forschungsanstalt fu¨r Lebensmittelchemie for measurements of
high resolution ESI–MS spectra. Assistance of Dr B. Wahl for X-
ray structure determination is highly appreciated, as well as helpful
discussions with Dr S. I. Vagin.
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