Palladium(II) complexes with phosphanylferrocenecarboxylate ligands and their use as catalyst precursors for semialternating CO-ethylene copolymerization

Article abstract of DOI:10.1002/ejic.200700903

Neutral [Pd(κP,κO-P～O)(κ³C,C,C- carbocycloenyl)] complexes, where P～O is a chiral or achiral chelating phosphanylferrocenecarboxylate ligand, were synthesized and characterized by multinuclear NMR spectroscopy. The crystal structure of a representative complex was determined by single-crystal X-ray diffraction analysis. In all complexes, the palladium(II) ion is located at the centre of a square plane formed by the P and O donor atoms from an anionic P～O^- ligand, a σ-carbon atom and a C-C double bond from a carbocycloenyl ligand. Neutral methyl complexes with the formulas [PdCl(Me)(κP,κH-P～OH)] and [Pd(Me)(OTs)(κP,κH-P～OH)] were also synthesized and characterized. On the basis of IR, NMR and MS-FAB data, the methyl complexes are proposed to be formulated with the fourth coordination position occupied by an agostic O-H...Pd interaction from a free carboxylic acid moiety [P～OH = 1′-(diphenylphosphanyl)ferrocenecarboxylic acid] or a solvent molecule. Selected complexes were employed as catalyst precursors for CO-ethylene copolymerization in MeOH in the presence of an excess of p-toluenesulfonic acid. In all cases, low molecular weight semialternating polyketones were produced. The catalytic activities were rather low and the extra-ethylene insertion reached a maximum value of 4.3%. An operando high-pressure NMR experiment with [Pd(Me)(S)₂(κP-P～OH)]OTs (S = solvent, adventitious water) precursor showed that this monocationic Pd^II alkyl complex is readily converted into a catalytically inactive binuclear carbonyl-bridged Pd ^I compound, which, however, regenerates catalytically active Pd ^II-H species by reaction with TsOH and that β-chelates of the formula [Pd(CH₂CH₂C(O)P)(S)(κP-P～OH)]OTs (P = propagating polyketone chain) are catalyst resting states. For the first time, β-chelate propagating species have been intercepted in a CO-olefin copolymerization assisted by catalysts devoid of a chelating ligand. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.

Full text of DOI:10.1002/ejic.200700903

FULL PAPER
DOI: 10.1002/ejic.200700903
Palladium(II) Complexes with Phosphanylferrocenecarboxylate Ligands and
Their Use as Catalyst Precursors for Semialternating CO–Ethylene
Copolymerization
Claudio Bianchini,[a] Andrea Meli,[a] Werner Oberhauser,*[a] Anna Maria Segarra,[a]
[b]
[c]
[c]
ˇ
ˇ
ˇ
ˇ
Elisa Passaglia, Martin Lamac, and Petr Stepnicka*
Keywords: Phosphanylferrocenecarboxylate ligands / Palladium / Semialternating ethylene–CO copolymerization / High-
pressure NMR spectroscopy
Neutral
[Pd(κP,κO-P~O)(κ3C,C,C-carbocycloenyl)]
com- ene copolymerization in MeOH in the presence of an excess
plexes, where P~O is a chiral or achiral chelating phosphan-
ylferrocenecarboxylate ligand, were synthesized and charac-
terized by multinuclear NMR spectroscopy. The crystal
structure of a representative complex was determined by sin-
gle-crystal X-ray diffraction analysis. In all complexes, the
palladium(II) ion is located at the centre of a square plane
formed by the P and O donor atoms from an anionic P~O–
ligand, a σ-carbon atom and a C–C double bond from a car-
bocycloenyl ligand. Neutral methyl complexes with the for-
mulas [PdCl(Me)(κP,κH-P~OH)] and [Pd(Me)(OTs)(κP,κH-
P~OH)] were also synthesized and characterized. On the ba-
sis of IR, NMR and MS–FAB data, the methyl complexes are
proposed to be formulated with the fourth coordination posi-
tion occupied by an agostic O–H···Pd interaction from a free
of p-toluenesulfonic acid. In all cases, low molecular weight
semialternating polyketones were produced. The catalytic
activities were rather low and the extra-ethylene insertion
reached a maximum value of 4.3%. An operando high-pres-
sure NMR experiment with [Pd(Me)(S)2(κP-P~OH)]OTs (S =
solvent, adventitious water) precursor showed that this
monocationic PdII alkyl complex is readily converted into a
catalytically inactive binuclear carbonyl-bridged PdI com-
pound, which, however, regenerates catalytically active PdII–
H species by reaction with TsOH and that β-chelates of the
formula [Pd(CH2CH2C(O)P)(S)(κP-P~OH)]OTs (P = propagat-
ing polyketone chain) are catalyst resting states. For the first
time, β-chelate propagating species have been intercepted
in a CO–olefin copolymerization assisted by catalysts devoid
carboxylic acid moiety [P~OH = 1Ј-(diphenylphosphanyl)fer- of a chelating ligand.
rocenecarboxylic acid] or a solvent molecule. Selected com-
plexes were employed as catalyst precursors for CO–ethyl-
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
sis.[2] The HLa ligand (Scheme 1) and some of its functional
derivatives have been used in palladium-catalyzed Suzuki
cross-coupling reactions[3] and as modifiers to MCM-41-
supported ruthenium catalysts in condensation reactions to
yield 2-oxopropyl benzoate.[4] In addition, rhodium(I) com-
plexes containing La– as a chelating phosphanyl-carboxyl-
ate ligand have been shown to efficiently catalyze the hydro-
formylation of 1-hexene.[5] These positive results prompted
us to scrutinize phosphanylferrocenecarboxylic acid ligands
in different types of C–C bond-forming reactions catalyzed
by palladium compounds.
Introduction
The organometallic chemistry of functionalized phos-
phanes modified with an additional (non-phosphane) do-
nor group is attracting considerable attention, predomi-
nantly because of its successful and varied applications in
homogeneous catalysis.[1] As a contribution to this area,
some of us have designed and synthesized several phoshan-
ylferrocenecarboxylic acid ligands (Scheme 1) and studied
their ability to coordinate to transition metals, with the ulti-
mate goal of utilizing the obtained compounds in cataly-
In this paper, we describe the synthesis and characteriza-
tion of new alkyl palladium(II) complexes with chelating
phosphanylferrocenecarboxylate ligands (Scheme 1) and re-
port on their use as catalyst precursors for the imperfectly
[a] Istituto di Chimica dei Composti Organometallici (ICCOM-
CNR), Area di Ricerca CNR di Firenze,
Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy
Fax: +39-0555-225-203
E-mail: werner.oberhauser@iccom.cnr.it
[b] ICCOM-CNR, Sezione di Pisa, c/o Dipartimento di Chimica e alternating (semialternating) CO–C2H4 copolymerization
Chimica Industriale,
Via Risorgimento 35, 56126 Pisa, Italy
[c] Charles University in Prague, Faculty of Science, Department
of Inorganic Chemistry,
(Scheme 2, a) either in batch reactors or in high-pressure
NMR (HPNMR) sapphire tubes.
The semialternating CO–C2H4 copolymerization is a re-
action of much current academic and industrial interest.[6,7]
Indeed, the stereoelectronic factors favouring semialter-
Hlavova 2030, 12840 Prague, Czech Republic
Fax: +420-221951253
E-mail: stepnic@natur.cuni.cz
Eur. J. Inorg. Chem. 2008, 441–452
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
441

ˇ
W. Oberhauser, P. Steˇpnicˇka et al.
FULL PAPER
Scheme 1.
on the mechanism of semialternation. However, much re-
mains to be elucidated, especially in regard to the species
that do control the extra-ethylene insertion.
Some authors have suggested that semialternation is a
result of the facile decarbonylation of Pd acyl species with
no intermediacy of β-chelates,[7e,7f] whereas others have pro-
posed that multiple-ethylene insertion is just facilitated by
the destabilization of neutral β-chelates.[7a,7d] More recently,
on the basis of operando HPNMR and model organome-
tallic studies, it has been demonstrated that i) PdII β-che-
lates are key intermediates in the catalysis cycle of semial-
ternation and their opening is a viable process by either
comonomer and ii) PdII(P~O) fragments do not form stable
carbonyl complexes.[7c]
Since the known catalysts for semialternating copolymer-
ization are nearly two orders of magnitude less active than
those producing strictly alternating copolymers, an increas-
ing amount of studies is being directed towards the design
of more active catalytic systems.
Scheme 2.
nation over perfect alternation (Scheme 2, b) are still at the
centre of an intense debate. In addition, semialternating po-
lyketones, featuring improved rheological properties relative
to perfectly alternating polyketones, are receiving increasing
attention as thermoplastics, compatibilizers and glue com-
ponents.
Semialternating polyketones can be obtained by either
free radical[6] or insertion polymerization reactions.[7] Drent
and coworkers have demonstrated that palladium(II) salts
modified with anionic chelating ligands bearing phospho-
rus and oxygen donor atoms (P~O–) constitute effective cat-
alysts for the synthesis of semialternating polyketones by
insertion polymerization.[7a] It is also agreed that nonalter-
nation is promoted by high temperatures (Ͼ100 °C), low
partial pressures of CO in the feed and appropriate substit-
uents on the P-aryl rings of the supporting P~O– ligand.[7]
Two examples of these ligands are shown in Scheme 3.
Results and Discussion
Synthesis of Palladium(II) Complexes
The reaction between sodium phosphanylferrocenecar-
boxylates, prepared in situ by reacting NaH with HLa,
HLb, HLc or HLd in CH2Cl2, and [PdCl(CODOMe)]2 (COD
= cycloocta-1,5-diene) gave the following neutral palladi-
um(II) phosphanyl-carboxylate complexes: [1Ј-(diphenyl-
phosphanyl-κP)ferrocenecarboxylato-κO](1η:5–6η-2-meth-
oxycyclooct-5-en-1-yl)palladium (1a), (Sp)-[2-(diphenyl-
phosphanyl-κP)ferrocenecarboxylato-κ2O,P](1η:5-6η-2-
methoxycyclooct-5-en-1-yl)palladium (1b), rac-[2-(di-
phenylphosphanyl-κP)ferrocenylacetato-κO](1η:5-6η-2-
Scheme 3.
Following Drent’s discovery, other authors have demon- methoxycyclooct-5-en-1-yl)palladium (1c), and rac-{2-[(di-
strated the effectiveness of P~O– ligands in nonalternating phenylphosphanyl-κP)methyl]ferrocenecarboxylato-κO}-
CO–C2H4 copolymerization, and their studiesϪboth exper- (1η:5-6η-2-methoxycyclooct-5-en-1-yl)palladium (1d)
imental[7b–7d] and theoretical[7e,7f]Ϫhave helped to shed light (Scheme 4).
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© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 441–452

Semialternating CO–Ethylene Copolymerization
Scheme 4.
Analogous reactions of NaLa and NaLc with [PdCl-
(DicpOEt)]2 (Dicp = dihydrodicyclopentadiene) gave [1Ј-(di-
phenylphosphanyl-κP)ferrocenylacetato-κO](1-2η,5η-6-
ethoxy-3a,4,5,6,7,7a-hexahydro-4,7-methanoindene)palla-
dium (2a) and rac-[2-(diphenylphosphanyl-κP)ferrocenyl-
acetato-κO](1-2η,5η-6-ethoxy-3a,4,5,6,7,7a-hexahydro-4,7-
methanoindene)palladium (2c) (Scheme 4).
The reaction between HLa and the [PdCl(Me)(η2:η2-
COD)] mononuclear precursor in CH2Cl2 yielded the neu-
tral chloro[1Ј-(diphenylphosphanyl)ferrocenylcarboxylic ac-
id](methyl)palladium complex, [PdCl(Me)(κP,κH-HLa)]
(3a), as an orange semicrystalline compound. Analogous
reactions with HLb, HLc and HLd also gave the corre-
sponding (chloro)methyl complexes, although these were
highly contaminated by unidentified species. Therefore, af-
ter several unsuccessful synthesis attempts, these reactions
were not investigated further.
Treatment of 3a with AgOTs in CH2Cl2 followed by the
addition of a mixture of diethyl ether and n-hexane to the
reaction solution led to the precipitation of the neutral
methyl derivative, [Pd(Me)(OTs)(κP,κH-HLa)] (4a), as a
yellow-orange powder.
Figure 1. ORTEP plot of 2c. Hydrogen atoms were omitted for
clarity. Thermal ellipsoids are shown at the 30% probability level.
All the new palladium complexes were characterized by
The palladium atom is positioned at the centre of a
NMR and IR spectroscopy and elemental analysis. In ad- square plane defined by the P(1) and O(1) atoms from the
dition, the solid-state structure of 2c was determined by sin- chelating Lc– ligand, the C(34) carbon atom and by the
gle-crystal X-ray diffraction analysis. Single crystals of 2c C(25)–C(26) double bond from the 6-ethoxy-exo-5,6-di-
were obtained by the slow evaporation of a CH2Cl2 solution hydrodicyclopentadienyl ligand. The maximum deviation
of the crude reaction product at room temperature. An from the least-squares plane defined by these atoms is
ORTEP drawing of the molecular structure of 2c is shown 0.091(1) Å for C(26). The P(1)–Pd(1)–O(1) bite angle of
in Figure 1, and selected bond lengths and angles are listed 99.97(9)° is slightly larger than that in the related Lc– com-
in Table 1.
plex, {2-[(dimethylamino-κN)methyl]phenyl-κC1}{rac-[2-
Eur. J. Inorg. Chem. 2008, 441–452
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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443

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W. Oberhauser, P. Steˇpnicˇka et al.
FULL PAPER
Table 1. Selected bond lengths [Å] and angles [°] for 2c.[a]
the formation of different dynamic species where the fourth
coordination position at palladium may be occupied by an
agostic H atom or, much more likely, by CH3OH or adven-
titious water. Consistent with this hypothesis, the same
spectrum in CD2Cl2 showed a very sharp methyl resonance
at δ = 6.92 ppm. The 31P{1H} NMR spectra in [D4]MeOH
or CD2Cl2 exhibited a singlet at δ = 30.9 or 28.16 ppm,
respectively, which is in line with the low trans influence
of the chloride atom. Indeed, trans-[PdCl2(HLa)2] shows a
31P{1H} NMR chemical shift of 15.8 ppm.[10] Taken al-
together, the spectroscopic characteristics of 3a are indica-
tive of a primary T-shaped coordination geometry, either in
the solid state or in apolar solvents, where the PdII centre
is surrounded by P, C(methyl) and Cl atoms. Such PdII
compounds are known in the literature to be stabilized by
bulky ligands capable of realizing agostic H-bonds to the
metal centre.[9] In this respect, the free carboxylic acid moi-
ety of HLa is an excellent candidate to bring about such an
intramolecular interaction. On the other hand, in polar
and/or coordinating solvents like methanol, it is much more
Bond or angle
Bond lengths [Å] and angles [°]
Pd(1)–P(1)
Pd(1)–O(1)
Pd(1)–C(25)
Pd(1)–C(26)
Pd(1)–C(34)
C(25)–C(26)
C(12)–O(1)
C(12)–O(2)
2.262(1)
2.152(3)
2.273(4)
2.409(4)
2.046(4)
1.357(6)
1.277(5)
1.232(6)
1.649(1)
1.652(1)
99.97(9)
88.94(12)
89.56(14)
78.73(13)
81.48(16)
92.76(15)
2.75(26)
Fe(1)–Cg(1)
Fe(1)–Cg(2)
P(1)–Pd(1)–O(1)
P(1)–Pd(1)–C(34)
O(1)–Pd(1)–C(25)
O(1)–Pd(1)–C(26)
C(25)–Pd(1)–C(34)
C(26)–Pd(1)–C(34)
Cp(1), Cp(2)
[a] Definitions of the ring planes: Cp(1) = C(1–5), Cp(2) = C(6–
10). Cg(1) and Cg(2) are the respective ring centroids.
(diphenylphosphanyl-κP)ferrocenyl]acetate-κO2}palladium likely that the fourth position at palladium be occupied by
[97.65(3)°].[8a] The carboxylate oxygen atom O(1) is trans to the solvent itself to give a complex with the formula
the σ-bonded C(34) atom with a O(1)–Pd(1)–C(34) angle of [PdCl(Me)(S)(κP-HLa)] (S = solvent, adventitious H2O).
170.89(14)° and, consequently, the phosphorus donor atom
Like for 3a, the characterization data for 4a are indicative
is trans to the C–C double bond. The latter shows an in- of a T-shaped coordination in both the solid state and in
terplanar angle of 70.83(19)° with the least-squares plane apolar solvents with the palladium centre surrounded by
defined by the Pd(1), P(1), O(1) and C(34) atoms. The trans Me and OTs groups and with HLa behaving as a “P,H-
disposition of the phosphorus donor atom and the C–C bidentate” ligand. CH2Cl2 solutions of 4a do not conduct,
double bond of the organyl ligand is consistent with the whereas this complex behaves as a 1:1 electrolyte in either
2JC,P value observed in the 13C{1H} NMR spectrum.[8]
nitroethane or MeOH. Therefore, 4a was tentatively as-
The geometry of the ferrocenyl backbone is quite regular, signed the formula [Pd(Me)(S)2(κP-HLa)]OTs in methanol
1
with the two cyclopentadienyl rings nearly coplanar and (S = methanol, adventitious H2O). The H and 13C{1H}
close to a syn-eclipsed conformation (the torsion angle is NMR spectra showed 4a to have a cis arrangement of the
ca. 11°). The Fe–Cg distances (the Cg’s are the centroids of P and C(methyl) atoms.
the Cp rings, as defined in Table 1) are 1.649(1) and
1.652(1) Å for Cg(1) and Cg(2), respectively. The coordina-
tion of the carboxylate moiety to palladium leads to a sig-
Catalytic Study
nificant elongation of the C=O double bond from 1.211(2)
(free ligand) to 1.232(6) Å, while the C–O single bond ployed as precatalysts for CO–C2H4 copolymerization in
shortens from 1.320(2) (free ligand) to 1.277(5) Å.[8a]
MeOH in the presence of different gas blends at a fixed
The neutral palladium complexes 1a–1d and 4a were em-
Unfortunately, no crystal of 3a suitable for X-ray analysis overall pressure of 800 psi and coreagents such as TsOH or
was obtained. The structure of this compound, as shown in 1,4-benzoquinone (BQ). The results of the catalytic study
Scheme 4, was therefore proposed on the basis of indirect are summarized in Table 2.
evidence as well as some precedents in the literature. The
The copolymer products showed keto and ester end
FAB-MS spectra in 2-nitrobenzyl alcohol matrix were con- groups in a 1:1 ratio and, most importantly, featured the
sistent with the formula PdCl(Me)(HLa) with no other li- imperfect alternation of CO and ethylene units. The molec-
gands. The solid IR spectrum (KBr, Nujol mull) showed a ular weights of the copolymers ranged from 13.4 to
ν(C=O) band at 1678 cm–1 with a shoulder at 1717 cm–1, 2.5 kgmol–1; this was dependent on the ethylene partial
whereas the IR spectrum in CH2Cl2 contained a single band pressure and the reaction temperature. Increasing the latter
at 1682 cm–1 [ν(C=O) bands at 1669 and 1677 cm–1 are ob- led to a significant decrease in the average molecular weight
served for the free HLa ligand in the solid- and solution- of the copolymers, likely because of acceleration of the
1
state spectra, respectively]. The H NMR spectra in [D4]- chain transfer reactions.[11]
MeOH or CD2Cl2 showed a doublet at δ = 0.68 or 0.80
In the absence of TsOH, no polyketone was produced
3
ppm with a JH,P value of 1.9 or 2.4 Hz, respectively, for because of the intrinsic instability of all catalyst precursors
the CH3 ligand, which should therefore be located cis to the that underwent irreversible degradation to palladium black
phosphorus atom.[9] The methyl group appeared as a broad (entries 1, 14 and 18 in Table 2).
singlet at δ = 4.87 ppm in the 13C{1H} NMR spectrum in
The beneficial action of strong protic acids on the ac-
[D4]MeOH. The broadness of this resonance may be due to tivity of CO–olefin copolymerization catalysts is well
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Eur. J. Inorg. Chem. 2008, 441–452

Semialternating CO–Ethylene Copolymerization
Table 2. Nonalternating CO–ethylene copolymerization in MeOH, tion, with a consequent decrease in productivity.[11] Under
catalyzed by the neutral palladium precursors 1a–1d and 4a.
the experimental conditions, no catalyst deactivation
Entry[a] Precursor TsOH CO/C2H4
t
[h]
Prod.[b]
Mn
% Extra
] C2H4
apparently occurred, and a nonlinear increase in productiv-
ity was observed, which is hard to rationalize. The most
straightforward interpretation is to think of a long induc-
tion period required to convert the precursor into catalyti-
cally active species that seem to change with time. Indeed,
a nonlinear increase in productivity [(gram polyketone)/
(mmole Pd)ϫhour] with time was observed: 2.4 after 3 h,
2.9 after 6 h and 10.2 after 11 h for 1a. Unfortunately, at
the reaction temperature, no species were seen on the NMR
timescale, which indicates the occurrence of fast equilibria
between different species. However, after activation and ca-
talysis, a unique β-chelate catalyst resting state was formed
(see below). In no case, however, was the productivity in
nonalternating polyketones comparable to that obtained
with the phosphane-sulfonate PdII catalysts reported by
Drent that are active even in the absence of added TsOH.[7a]
Notably, the use of 4a as precursor (entries 14–17) in the
place of 1a (entries 1, 5, 6 and 10) gave almost identical
results, which suggests that 1a and 4a generate the same
catalyst. This evidence is also an indirect confirmation that
TsOH protonates the bonded carboxylate group in 1a,
which results in the formation of a free –C(O)OH moiety.
To our surprise, the addition of an organic oxidant such
as BQ to the reaction mixtures decreased the catalytic pro-
ductivity (entries 7 and 22 vs. 6 and 21, respectively). In-
deed, like protic acids, BQ is a coreagent that almost invari-
ably increases the productivity of PdII-assisted CO–olefin
copolymerization reactions by oxidizing inactive low valent
Pd species. On the other hand, it is known that BQ also has
the effect of converting PdII–H into PdII–OMe initiators.[11]
Thus, this experimental evidence could be the indirect con-
(equiv.)
ratio
[kgmol–1
1
2
3[c]
4
5
6
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
1a
4a
4a
4a
4a
1b
1b
1b
1b
1b
1b
1b
1b
1b
1c
1d
0
1:3
1:3
1:3
1:3
1:3
1:3
1:3
1:3
1:3
1:3
1:3
1:1
1:6
1:3
1:3
1:3
1:3
1:3
1:3
1:3
1:3
1:3
1:3
1:3
1:3
1:1
1:3
1:3
11
11
11
3
0.0
5.3
2.5
2.4
2.9
10.2
2.7
0.8
0.6
9.9
3.5
3.4
1.5
0.0
2.9
10.1
9.9
0.0
3.0
2.9
4.5
1.3
1.9
3.4
2.4
1.4
0.1
0.1
10
10
19
19
19
19
19
19
19
38
19
19
0
7.6
7.2
1.3
1.2
6
11
11
11
11
17
11
11
11
11
6
11
17
11
11
6
11
11
11
17
11
11
11
11
6.4
3.4
1.7
2.2
7[d]
8[e]
9[f]
10
11
12
13
14
15
16
17
18
19
20
21
22[d]
23[e]
24
25
26
27
28
6.4
7.2
13.4
5.2
1.8
2.3
1.5
2.4
18
18
18
0
6.2
6.9
1.8
2.2
10
19
19
19
19
19
38
19
19
19
2.5
2.4
9.5
4.3
2.9
1.8
[a] Reaction conditions: precursor (0.012 mmol), MeOH (50 mL),
100 °C, total pressure p at reaction temperature: p = 800 psi. [b]
Productivity expressed as (grams polyketone)/(mmole Pd)ϫhour.
[c] NaOTs (9 equiv.). [d] BQ (40 equiv.). [e] 120 °C. [f] 80 °C.
known. Besides neutralizing anionic nucleophiles that may firmation that the CO–ethylene copolymerization mecha-
compete with monomers or with the MeOH required to nism with the phosphanylferrocenecarboxylic acid/palla-
activate the precursors,[11] strong protic acids convert inac- dium catalysts involves PdII–H initiators and that chain
tive Pd0 species into active PdII–H initiators. Accordingly, transfers occur by methanolysis.[11]
a partial substitution of TsOH with its sodium salt led to a
The catalytic activities of 1a and 1b were also influenced
remarkable decrease in productivity (entry 2 vs. entries 3 by the gas blend, with the optimum CO/C2H4 ratio being
and 6 in Table 2). In the present catalytic systems, TsOH 1:3. Indeed, analogous catalytic reactions carried out in the
has the additional role of transforming neutral compounds presence of either 1:1 or 1:6 gas mixtures gave a lower pro-
into cationic ones with a phosphanyl-carboxylic acid ligand ductivity. In general, a high concentration of CO stabilizes
(see below).
Pd(acyl)(CO) species, while a low concentration can slow
The palladium precursors with La– and Lb– showed a down the rate of β-chelate opening, which is a key step of
maximum activity in the presence of 18–19 equiv. of acid chain propagation (see below).[11,12]
and a 1:3 CO/C2H4 ratio (entries 6, 16 and 21 in Table 2).
The degree of extra-ethylene insertion as well as the oc-
Increasing the amount of TsOH to 38 equiv. (entries 11 and currence of double ethylene insertions in the polymeric
25 in Table 2) significantly decreased the productivity, chain were monitored by 13C{1H} NMR measurements in
which suggests that too large a concentration of p-toluene- a (1:1, v/v) solvent mixture of 1,1,1,3,3,3-[D2]hexafluoro-2-
sulfonate ions in the reaction mixture disfavours monomer propanol (HFIP) and C6D6. In addition to signals due to
coordination to palladium.[11] Under comparable condi- perfectly alternating copolymers, the spectra showed three
tions, 1c and 1d yielded only traces of polymeric material additional singlets at δ 21.55, 40.14 and 212.50 ppm due
along with extensive catalyst degradation to palladium to extra-ethylene insertion.[7a] In agreement with previous
black (entries 27 and 28 in Table 2).
reports, we have found that higher temperatures and lower
The catalytic activity of 1a and 1b increased significantly partial pressures of CO, at constant total pressure, favour
with time (entries 4–6, 15,16, 20 and 21 in Table 2). This the extra enchainment of ethylene. The maximum extra in-
finding is quite interesting as PdII-catalyzed CO–ethylene sertion was around 4.3% for 1b at 100 °C (entry 24 in
copolymerization reactions suffer from catalyst deactiva- Table 2). The amount of added TsOH did not significantly
Eur. J. Inorg. Chem. 2008, 441–452
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445

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W. Oberhauser, P. Steˇpnicˇka et al.
FULL PAPER
influence the amount of extra-ethylene insertion (entries 2, ment). Within 20 min at room temperature, 5a was con-
6 and 11 or 21 and 25). verted almost completely into 6a (Figure 2, trace c) with
Some reactions with precatalysts 1a and 1b were per- formation of the CH3C(O)OCD3 ester (GC-MS evidence),
formed in the presence of only ethylene (i.e., without CO). hence through a reaction sequence involving the meth-
Only traces of but-1-ene and cis/trans-but-2-ene were ob- anolysis of 5a to yield a transient Pd-H species (Scheme 5).
tained, which suggests that only double ethylene insertion At this stage, the HPNMR tube was pressurized with ethyl-
is actually promoted by the present catalysts.
ene (600 psi) at room temperature (1:3 CO/C2H4 mixture),
but no change was observed (Figure 2, trace d). Only upon
heating to 50 °C did 6a disappear, and no trace of this com-
pound was seen after 30 min at 100 °C. During this time,
copolymer formation occurred (Figure 2, traces e and f).
After the sapphire tube was cooled to room temperature,
the spectrum showed a new broad singlet at δ = 29.20 ppm
(Figure 2, trace g).
Operando 31P{1H} HPNMR Study
In an attempt to intercept some intermediates that might
help to clarify the mechanism by which the phosphanyl-
ferrocenecarboxylate catalysts operate to produce nonalter-
nating polyketones, an operando HPNMR experiment was
carried out using 4a as precursor with a 1:3 CO/C2H4 mix-
ture at an overall pressure of 800 psi. The reactions were
followed by variable-temperature 31P{1H} and 1H NMR
spectroscopy. Selected 31P{1H} NMR spectra are reported
in Figure 2.
Figure 2. Variable-temperature 31P{1H} HPNMR study of the CO–
C2H4 copolymerization reaction with 4a/TsOH [sapphire tube,
[D4]MeOH, TsOH (18 equiv.), 81.01 MHz]: (a) 4a/TsOH at room
temperature; (b) immediately after charging with CO (200 psi); (c)
after 20 min under CO; (d) immediately after charging with C2H4
(600 psi); (e) at 50 °C; (f) after 30 min at 100 °C; (g) after cooling
to room temperature.
Scheme 5. Cationic palladium complexes observed by operando
HPNMR spectroscopy in the CO–C2H4 copolymerization reaction
catalyzed by 4a/TsOH in [D4]MeOH.
To a [D4]MeOH solution of 4a (31P{1H} NMR: δ =
The identification of the species responsible for the sing-
32.90 ppm) was added TsOH (18 equiv.), and the resulting let at δ = 29.20 ppm, quoted as 7aM, was carried out in an
mixture was transferred into a 10 mm HPNMR sapphire indirect way. Some previous studies of nonalternating CO–
tube under nitrogen (31P{1H} NMR singlet at δ = C2H4 copolymerization catalyzed by PdII(P~O) complexes
33.50 ppm; Figure 2, trace a). On pressurizing the sapphire {P~O = 2-[bis(o-methoxyphenyl)phosphanyl]phenylenesul-
tube with CO (200 psi) at room temperature, two new fonate and 2-[bis(o-methoxyphenyl)phosphanyl]ethylenesul-
31P{1H} NMR singlets appeared (Figure 2, trace b). One is fonate, Scheme 3} had revealed that the catalyst resting
at δ = 22.80 ppm and we attribute it to the acyl complex 5a state consisted of β-chelate species of the type shown in part
on the basis of a multinuclear NMR analysis (Scheme 5). a of Scheme 6 (P = propagating chain).[7c] With this in
The identification of the species responsible for the second mind, we synthesized in situ the first-generation β-chelate
peak at δ = 11.05 ppm was less straightforward. We are in- complex {Pd[CH2CH2C(O)CH3](κP,κH-HLa)}BArЈ4 [ArЈ
clined to assign this singlet to a binuclear CO-bridged PdI = 3,5-bis(trifluoromethyl)phenyl] (7a) from 3a by a well-
complex (6a) on the basis of its high-field 31P NMR reso- known stepwise process involving the carbonylation of the
nance as well as the detection of a unique 13C{1H} NMR starting compound in CD2Cl2, followed by treatment of the
carbonyl resonance at δ = 222.48 ppm (obtained by using a acyl product with a chloride scavenger (NaBArЈ4) under an
1:9 13CO/12CO mixture at 200 psi in an independent experi- ethylene atmosphere (Scheme 6, b).
446
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Semialternating CO–Ethylene Copolymerization
the key role of such species in the nonalternating CO–C2H4
copolymerization reaction.[7a,7c,7d] Finally, it is worth stress-
ing that this paper reports the first evidence of β-chelate
PdII complexes derived from CO and ethylene with no need
of a chelating ligand.
In an attempt to avoid the formation of monodentate
phosphane ligands, which may be responsible for the low
catalytic activity observed, studies are in progress in our
laboratories aimed at replacing the –C(O)OH moiety in the
phosphanylferrocene ligands with a functional group fea-
turing a stronger Brønsted acidity.
Scheme 6.
Experimental Section
General Procedures: All reactions and manipulations were carried
out under a nitrogen atmosphere by using standard Schlenk tech-
niques. Solvents were distilled from suitable dehydrating reagents
and were deoxygenated before use. Reagents were used as received
Compound 7a was characterized in situ by 1H NMR and
IR spectroscopy. A cis arrangement of the P and C atoms
bound to palladium was established by NMR spectroscopy,
while the IR spectrum showed the presence of a coordi- from Aldrich or Fluka, unless stated otherwise. Compounds
HLa,[13a] HLb,[13b] HLc,[8a] HLd,[13c] [PdCl(CODOMe)]2,[14a]
nated C=O group.[11,12] Like 3a and 4a in apolar solvents,
7a is drawn with a proposed Pd–H interaction.[9] As ex-
pected, 7a and 7aM in [D4]MeOH showed the same 31P{1H}
NMR spectra corresponding to structures where HLa be-
haves as a monodentate ligand through its phosphorus
atom. Obviously, 7aM represents a family of β-chelates con-
taining propagating chains of different lengths (Scheme 5).
At the end of the HPNMR experiment illustrated in Fig-
ure 2, the sapphire tube was vented with a nitrogen flow to
[15]
[PdCl(DicpOEt)]2,[14b] PdCl(Me)(COD)[14c] and NaBArЈ4
were
prepared according to the literature methods. Copolymerization re-
actions were performed in a 200 mL stainless steel autoclave con-
structed at ICCOM-CNR (Florence, Italy) and equipped with a
magnetic drive stirrer and a homemade temperature and pressure
controller. The autoclave was connected to a gas reservoir to main-
tain constant pressure during the catalytic reactions. GC-MS analy-
ses were performed with a Shimadzu QP2100S apparatus equipped
with
a
SPB-1 Supelco fused silica capillary column
remove all unreacted gases, and a thin layer of semialternat- (30 mϫ0.25 mm, 0.25 µm film thickness). Deuterated solvents for
routine NMR measurements were dried with activated molecular
sieves. 1H, 13C{1H} and 31P{1H} NMR spectra were obtained with
either a Bruker ACP 200 (200.13, 50.32 and 81.01 MHz, respec-
tively) or a Bruker Avance DRX-400 spectrometer (400.13, 100.62
and 161.98 MHz, respectively). Chemical shifts (δ) are reported in
ppm relative to TMS, and referenced to the chemical shifts of resid-
ual solvent resonances (1H and 13C NMR) or 85% H3PO4 (31P
NMR). The assignment of 1H and 13C signals is based on 2D
ing polyketone was collected at the gas–liquid interphase.
A GC-MS analysis of the reaction solution showed the for-
mation of CH3C(O)OCD3 which resulted from the meth-
anolysis of 5a (Scheme 5).
Conclusions
1
NMR experiments (1H COSY and H–13C HMQC). See Scheme 7
New neutral PdII complexes containing either chelating
phosphanylferrocenecarboxylate or monodentate phos-
phanylferrocenecarboxylic acid ligands were synthesized
and characterized. Selected complexes were used as precata-
lysts for the CO–C2H4 copolymerization in MeOH in the
presence of an excess of TsOH with different gas blends,
and at a fixed overall pressure of 800 psi and temperatures
Ն100 °C. Under these experimental conditions, semialter-
nating polyketones with extra-ethylene incorporation up to
4.3% were obtained. The productivities were quite modest:
an order of magnitude lower than those obtainable with
PdII catalysts supported by chelating phosphanylphenylene-
sulfonate ligands.[7a–7c] Surprisingly, however, the productiv-
ities increased with time, which may be due to a very long
induction period required for the conversion of the precur-
sors into more than one catalytically active species. An op-
erando HPNMR study has revealed that the neutral precur-
sors are converted into cationic monophosphane alkyl com-
plexes by protonation of the carboxylate group. More im-
portantly, the operando experiment has shown the forma-
for the atom labeling of palladium complexes 1a–1d, 2a, 2c, 3a and
4a. HPNMR experiments were carried out with a Bruker ACP 200
using a 10 mm sapphire NMR tube (Saphikon, Milford, NH)
equipped with a titanium high-pressure charging head constructed
at the ICCOM-CNR (Florence, Italy).[16] Elemental analyses were
performed using a Carlo–Erba Model 1106 elemental analyzer. The
conductivity measurement was carried out with an Orion model
101 conductivity meter with a 10–3  MeOH solution.[17] Infrared
spectra were recorded with an FT-IR Perkin–Elmer Spectrum GX
instrument. FAB-MS measurements were carried out with a Finni-
gan MAT-95 instrument.
Synthesis of 1a: Solid sodium hydride (3.9 mg, 0.17 mmol) was
added to a solution of HLa (70.3 mg, 0.17 mmol) in CH2Cl2
(10 mL) at room temperature. The mixture was stirred for 30 min
while the orange precipitate of NaLa separated. A solution of
[PdCl(CODOMe)]2 (44.9 mg, 0.08 mmol) in CH2Cl2 (2 mL) was
added, and the resulting mixture was stirred at room temperature
for 1 h and then filtered through a plug of Celite to remove NaCl.
The filtrate was concentrated to a small volume (ca. 4 mL). Ad-
dition of diethyl ether led to the precipitation of 1a as a brown
microcrystalline solid, which was filtered, washed with diethyl ether
tion of β-chelates as catalyst resting states, which confirms and dried in
a
stream of nitrogen. Yield 89.5 mg (80%).
Eur. J. Inorg. Chem. 2008, 441–452
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447

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W. Oberhauser, P. Steˇpnicˇka et al.
FULL PAPER
Scheme 7. Atom labeling of isolated palladium complexes 1a–1d, 2a, 2c, 3a and 4a.
C32H33FeO3PPd (658.6): calcd. C 58.36, H 5.01; found C 58.67, H
brown microcrystals, which were filtered, washed with diethyl ether
and dried in stream of nitrogen. Yield 94.7 mg (80%).
5.10. 1H NMR (400.13 MHz, CD2Cl2, 25 °C): δ = 1.80 (m, 1 H,
a
31-H), 1.95–2.15 (m, 2 H, 26-H), 2.20–2.40 (m; 4 H; 24-H, 30-H C35H33FeO3PPd (696.6): calcd. C 60.35, H 5.02; found C 60.53, H
1
3
and 31Ј-H), 2.46 (s, 3 H, 32-H), 2.80 (m, 2 H, 27-H), 2.91 (br. s, 1 5.08. H NMR (400.13 MHz, CD2Cl2, 25 °C): δ = 0.99 (t, JH,H
=
2
H, 25-H), 4.23 and 4.27 (s, 2 H, 8-H and 9-H), 4.31 (s, 1 H, 2-H), 7.0 Hz, 3 H, 35-H), 1.10 (d, JH,H = 9.7 Hz, 1 H, 28-H), 1.29 (d,
3
4.36 (s, 1 H, 5-H), 4.54 (s, 1 H, 3-H), 4.64 (s, 1 H, 4-H), 4.71 and
4.75 (s, 2 H, 7-H and 10-H), 6.62 (m, 1 H, 29-H), 6.98 (m, 1 H,
2JH,H = 9.7 Hz, 1 H, 28Ј-H), 1.69 (dd, JH,H = 15.6 and 3.8 Hz, 1
3
H, 31-H), 2.37 (d, JH,H = 4.9 Hz, 1 H, 32-H), 2.43 (m, 1 H, 33-
28-H), 7.48 (m; 6 H; 14-H, 15-H, 16-H, 20-H, 21-H and 22-H), H), 2.74–2.81 (m, 2 H, 26-H and 33Ј-H), 2.87 (m, 1 H, 27-H), 3.04
3
3
7.60–7.69 (dd; JH,H = 8.0 and JP,H = 10.6 Hz; 4 H; 13-H, 17-H,
(m, 1 H, 25-H), 3.20 (m, 1 H, 34-H), 3.42 (m, 1 H, 34-H), 3.81 (d,
19-H and 23-H) ppm. 13C{1H} NMR (100.62 MHz, CD2Cl2, 2JH,H = 6.5 Hz, 24-H), 4.17 (br. s, 1 H, 2-H), 4.22 (br. s, 1 H, 7-
25 °C): δ = 25.28 (s, C-30), 28.37 (s, C-27), 31.55 (s, C-26), 35.65 H), 4.30 (br. s, 1 H, 10-H), 4.42 (br. s, 1 H, 5-H), 4.53 (br. s, 1 H,
(s, C-31), 43.41 (s, C-24), 55.17 (s, C-32), 70.85 (s, C-8 and C-9),
3-H), 4.58 (br. s, 1 H, 4-H), 4.78 (br. s, 1 H, 8-H), 4.97 (br. s, 1 H,
71.80 (br. s, C-3), 72.12 and 73.59 (s, C-7 and C-10), 72.93 (d, 3JC,P 9-H), 6.74 (br. s, 1 H, 29-H), 7.44 and 7.78 (m, 13-H–17-H and 19-
2
2
= 6.8 Hz, C-4), 74.96 (d, JC,P = 8.1 Hz, C-2), 76.22 (d, JC,P
=
H–23-H), 7.65 (br. s, 1
H, 30-H) ppm. 13C{1H} NMR
15.1 Hz, C-5), 81.47 (s, C-25), 120.56 (br. s, C-28), 123.31 (br. s, C- (100.62 MHz, CD2Cl2, 25 °C): δ = 15.32 (s, C-35), 31.76 (s, C-33),
29), 128.53 (s; C-14, C-16, C-20 and C-22), 130.74 (s, C-15 and C-
35.64 (s, C-28), 39.32 (s, C-26), 41.73 (s, C-32), 52.00 (s, C-24),
53.00 (s, C-31), 57.75 (s, C-27), 63.79 (s, C-34), 70.40 (s, C-7), 70.52
1
21), 131.69 (d, JC,P = 4.3 Hz, C-12 and C-18), 133.89 (br. s; C-
13, C-17, C-19 and C-23), 175.31 (s, C-11) ppm. 31P{1H} NMR
(s, C-10), 71.30 (d, JP,C = 37.9 Hz, C-1), 71.80 (d, JP,C = 5.7 Hz),
1
3
3
(161.98 MHz, CD2Cl2, 25 °C): δ = 19.93 ppm.
72.40 (d, JP,C = 8.3 Hz, C-4), 72.50 (s, C-9), 73.00 (s, C-8), 75.10
2
2
(d, JP,C = 8.4 Hz, C-2), 75.60 (d, JP,C = 15.0 Hz, C-5), 81.08 (s,
Synthesis of 2a: Solid sodium hydride (3.9 mg, 0.17 mmol) was
added to a solution of HLa (70.3 mg, 0.17 mmol) in CH2Cl2
(10 mL). The mixture was stirred at room temperature for 30 min
while the orange precipitate of NaLa separated. Addition of a solu-
tion of [PdCl(DicpOEt)]2 (51.0 mg, 0.08 mmol) in CH2Cl2 (2 mL) to
the obtained suspension afforded an orange solution, which was
stirred at room temperature for 2 h, filtered through a plug of Celite
to remove NaCl and concentrated to a small volume (4 mL). Ad-
dition of diethyl ether led to the precipitation of 2a as orange-
3
C-25), 81.12 (s, C-6), 128.29 (d; JP,C = 10.5 Hz; C-14, C-16, C-20
and C-22), 130.20 (s, C-15 and C-21), 130.28 (s, C-29), 130.80 (s,
1
C-30), 132.88 (d, JP,C = 47.2 Hz, C-12 and C-18), 132.91, 135.10
3
(d; JP,C = 11.7 Hz; C-13, C-17, C-19 and C-23), 174.67 (s, C-11)
ppm. 31P{1H} NMR (161.98 MHz, CD2Cl2, 25 °C): δ = 21.37 ppm.
Synthesis of 3a: A solid sample of PdCl(Me)(COD) (63.6 mg,
0.24 mmol) was added to a solution of HLa (100.0 mg, 0.24 mmol)
in CH2Cl2 (7 mL). The reaction mixture was stirred for 1 h and
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Semialternating CO–Ethylene Copolymerization
concentrated to half of its original volume. The addition of diethyl
ether (12 mL) to this precipitated 3a as an orange microcrystalline
solid, which was filtered, washed with diethyl ether (2ϫ6 mL) and
at room temperature showed the presence of CH3C(O)OCD3 and
the two complexes {Pd(CO)[C(O)CH3}(HLa)]OTs (5a) and
[Pd(CO)(HLa)]2OTs (6a). The transformation of 5a into 6a was
complete within 2 h at room temperature. Selected NMR spectro-
dried in
a
stream of nitrogen. Yield 109.6 mg (80%).
1
C24H22ClFeO2PPd (570.9): calcd. C 50.49, H 3.85; found C 50.66,
scopic data for 5a: H NMR (200.13 MHz, [D4]MeOH, 25 °C): δ
H 3.92. 1H NMR (400.13 MHz, [D4]MeOH, 25 °C): δ = 0.68 (d, = 2.11 [d, 4JH,P = 1.82 Hz, 3 H, PdC(O)CH3] ppm. 13C{1H} NMR
3JH,P = 1.9 Hz, 3 H, 24-H), 4.48 (s, 2 H, 2-H and 5-H), 4.53 (s, 2 (50.32 MHz, [D4]MeOH, 25 °C): δ = 31.50 [d, JC,P = 28.8 Hz,
3
2
H, 3-H and 4-H), 4.75 (s, 2 H, 8-H and 9-H), 4.95 (s, 2 H, 7-H and
PdC(O)CH3], 219.81 [s, PdC(O)CH3], 228.50 (d, JC,P = 78 Hz,
PdCO) ppm. 31P{1H} NMR (81.01 MHz, [D4]MeOH, 25 °C): δ =
22.85 (s) ppm. Selected NMR spectroscopic data for 6a: 13C{1H}
NMR (50.32 MHz, [D4]MeOH, 25 °C): δ = 222.48 (s, PdCO) ppm.
3
10-H), 7.43 (t; JH,H = 6.4 Hz; 4 H; 14-H, 16-H, 20-H and 22-H),
3
4
7.48 (m, JH,H = 6.7 and JH,H = 6.1 Hz, 2 H, 15-H and 21-H),
3
3
7.59 (dd; JH,P = 11.4 and JH,H = 7.6 Hz; 4 H; 13-H, 17-H, 19-H
and 23-H) ppm. 13C{1H}NMR (100.62 MHz, [D4]MeOH, 25 °C): 31P{1H} NMR (81.01 MHz, [D4]MeOH, 25 °C): δ = 11.02 (s) ppm.
δ = 4.87 (br. s, C-24), 71.83 (s, C-7 and C-10), 72.47 (s, C-6), 73.61
In situ Synthesis of 7a: CO was bubbled through a solution of 3a
(22.8 mg, 0.04 mmol) in CD2Cl2 (1.2 mL) in a Schlenk tube for
10 min at room temperature. After nitrogen was bubbled through
the resulting solution to eliminate excess CO, ethylene was bubbled
through it, and then a solid sample of NaBArЈ4 (44.3 mg,
0.05 mmol) was added to the solution to scavenge the chloride li-
gand from Pd. The suspension was stirred for 2 min and filtered
under nitrogen, and the filtrate was transferred into a 5 mm NMR
tube. The atom labelling of the hydrogen atoms of the Cp rings
corresponds to that applied for 3a and 4a. 1H NMR (400.13 MHz,
CD2Cl2, 25 °C): δ = 1.85 (s, 2 H, PdCH2), 2.49 [s, 3 H, C(O)CH3],
2.95 (br. s, 2 H, CH2CO), 4.35 (br. s, 2 H, 2-H and 5-H), 4.70 (br.
s; 4 H; 3-H, 4-H, 8-H and 9-H), 5.45 (br. s, 2 H, 7-H and 10-
H), 7.35–7.90 (m, 22 H, Ar-H) ppm. 31P{1H} NMR (161.98 MHz,
3
(d, JC,P = 7.3 Hz, C-3 and C-4), 74.70 (s, C-8 and C-9), 75.08 (d,
2
1JC,P = 27.9 Hz, C-1), 75.43 (d, JC,P = 10.8 Hz, C-2 and C-5),
3
127.86 (d; JC,P = 10.8 Hz; C-14, C-16, C-20 and C-22), 130.36 (s,
C-15 and C-21), 131.92 (d, 1JC,P = 53.3 Hz, C-12 and C-18), 133.61
2
(d; JC,P = 11.5 Hz; C-13, C-17, C-19 and C-23), 173.38 (s, C-11)
ppm. 31P{1H} NMR (161.98 MHz, [D4]MeOH, 25 °C): δ = 30.90
ppm. IR (KBr, Nujol mull): ν = ν(C=O) 1678, 1717 (sh) cm–1. IR
˜
(CH Cl ): ν = ν(C=O) 1682 cm–1. FAB-MS: m/z (%) = 568.63
˜
2
2
(100), 570.63 (90) [M].
Synthesis of 4a: Solid Ag(OTs) (22.4 mg, 0.08 mmol) was added to
a solution of 3a (45.6 mg, 0.08 mmol) in deaerated CH2Cl2
(10 mL). The suspension was stirred at room temperature for
10 min, and filtered through a plug of Celite. The orange solution
was then concentrated to half of its original volume (5 mL), and
the addition of a 1:1 (v/v) mixture of diethyl ether and n-hexane
caused the precipitation of a yellow-orange powder, which was fil-
tered off, washed with diethyl ether (3 mL) and dried in a stream
of nitrogen. Yield 45.9 mg (85%). C31H29FeO5PPd (674.5): calcd.
C 55.20, H 4.30; found C 55.10, H 4.15. 1H NMR (400.13 MHz,
CD Cl , 25 °C): δ = 29.6 (s) ppm. IR (CH Cl ): ν = ν(C=O) 1636
˜
2
2
2
2
[C(O)CH3], 1655 [C(O)OH] cm–1.
Synthesis of 1b: A procedure analogous to that described above for
1a that substituted HLb for HLa was followed to give 1b as a
brown crystalline solid. Yield 91.8 mg (82%). C32H33FeO3PPd
(658.6): calcd. C 58.36, H 5.01; found C 58.45, H 5.08. Dia-
stereoisomer ratio A/B = 1:1. Diasteroisomer A: 1H NMR,
(400.13 MHz, CD2Cl2, 25 °C): δ = 1.80–3.60 (9 H; 24-H, 26-H, 27-
H, 30-H and 31-H), 2.72 (s, 3 H, 32-H), 2.92 (m, 1 H, 25-H), 3.95
3
CD2Cl2, 25 °C): δ = 0.64 (d, JH,P = 1.6 Hz, 3 H, 24-H), 2.42 (s, 3
H, Ar-CH3), 4.39 (m, 2 H, 2-H and 5-H), 4.63 (s, 2 H, 3-H and 4-
3
H), 4.73 (s, 4 H, 7-H–10-H), 7.28 (d, JH,H = 10.8 Hz, 2 H, Ar-H),
3
4
3
7.42–7.64 (m, 10 H, 13-H–17-H and 19-H–23-H), 7.81 (d, JH,H
=
(q, JP,H = 3.9 and JH,H = 2.4 Hz, 1 H, 3-H), 4.42 (s, 5 H, 6-H–
10.8 Hz, 2 H, Ar-H) ppm. 13C{1H} NMR (100.62 MHz, CD2Cl2,
3
10-H), 4.56 (t, JH,H = 2.6 Hz, 1 H, 4-H), 5.20 (m, 1 H, 5-H), 6.22
25 °C): δ = 7.20 (s, C-24), 21.11 (s, Ar-CH3), 73.44 (s, C-7 and C-
(m, 1 H, 29-H), 6.65 (m, 1 H, 28-H), 7.30–7.88 (m, overlapping
signals with diastereoisomer B, 13-H–17-H and 19-H–23-H) ppm.
13C{1H} NMR (100.62 MHz, CD2Cl2, 25 °C): δ = 25.49 (s, C-30),
29.04 (s, C-27), 31.42 (s, C-26), 35.88 (s, C-31), 40.43 (s, C-24),
3
10), 73.66 (s, C-6), 73.80 (d, JC,P = 10.0 Hz, C-3 and C-4), 73.97
1
2
(s, C-8 and C-9), 74.50 (d, JC,P = 62.6 Hz, C-1), 78.17 (d, JC,P
=
3
17.0 Hz, C-2 and C-5), 126.1 (s, Ar-C) 128.39 (d; JC,P = 15.0 Hz;
1
C-14, C-16, C-20 and C-22), 129.0 (s, Ar-C), 131.08 (s, C-15 and
55.31 (s, C-32), 70.71 (d, JC,P = 53.8 Hz, C-1) (C-2 overlapped),
1
2
3
C-21), 131.22 (d, JC,P = 76.5 Hz, C-12 and C-18), 133.98 (d; JC,P
= 16.1 Hz; C-13, C-17, C-19 and C-23), 140.71 (s, Ar-C), 141.27 (s,
Ar-C), 181.02 (s, C-11) ppm. 31P{1H} NMR (161.98 MHz, CD2Cl2,
71.61 (s, C-6–C-10), 72.70 (d, JC,P = 6.2 Hz, C-4), 73.81 (s, C-3),
2
2
75.78 (d, JC,P = 6.8 Hz, C-5), 82.75 (s, C-25), 119.15 (d, JC,P
=
=
2
1
8.1 Hz, C-28), 124.52 (d, JC,P = 9.4 Hz, C-29), 127.89 (d, JC,P
51.9 Hz, C-12 and C-18), 128.77 and 128.92 (d; JC,P = 10.6 and
25 °C): δ = 33.08 ppm. IR (CH Cl ): ν = ν(C=O) 1683 cm–1. Λ
3
˜
2
2
M
(nitroethane): 57 Ω–1 cm2 mol–1.
11.3 Hz, respectively; C-14, C-16, C-20 and C-22), 130.42 and
4
131.04 (d, JC,P = 1.5 Hz, C-15 and C-21), 132.91 and 133.20 (d;
In Situ Synthesis of 4a in [D4]MeOH: Solid Ag(OTs) (5.6 mg,
0.02 mmol) was added to a solution of 3a (11.4 mg, 0.02 mmol) in
[D4]MeOH (2 mL). The suspension was stirred at room tempera-
ture for 10 min, and then filtered through a plug of Celite. The
filtrate was then transferred under nitrogen into a 5 mm NMR
tube. Selected NMR spectroscopic data: 1H NMR (400.13 MHz,
[D4]MeOH, 25 °C): δ = 0.78 (d, 2JH,P = 0.7 Hz, 3 H, PdCH3) ppm.
13C{1H} NMR (100.62 MHz, [D4]MeOH, 25 °C): δ = 0.26 (d, 2JC,P
= 4.6 Hz, PdCH3) ppm. 31P{1H} NMR (161.98 MHz, [D4]MeOH,
25 °C): δ = 32.9 (s) ppm. ΛM (MeOH): 67 Ω–1 cm2 mol–1.
2JC,P = 12.8 and 11.3 Hz, respectively; C-13, C-17, C-19 and C-23),
171.74 (s, C-11) ppm. 31P{1H} NMR (161.98 MHz, CD2Cl2,
1
25 °C): δ = 16.20 ppm. Diasteroisomer B: H NMR (400.13 MHz,
CD2Cl2, 25 °C): δ = 1.80–3.60 (9 H; 24-H, 26-H, 27-H, 30-H and
4
31-H), 2.85 (s, 3 H, 32-H), 3.52 (m, 1 H, 25-H), 4.03 (q, JP,H
=
3
3.9 and JH,H = 2.4 Hz, 1 H, 3-H), 4.19 (s, 5 H, 6-H–10-H), 4.53
(t, JH,H = 2.6 Hz, 1 H, 4-H), 5.21 (m, 1 H, 5-H), 6.27 (m, 1 H,
3
29-H), 6.75 (m, 1 H, 28-H), 7.30–7.88 (m, overlapping signals with
diastereoisomer A, 13-H–17-H and 19-H–23-H) ppm. 13C{1H}
NMR (100.62 MHz, CD2Cl2, 25 °C): δ = 25.62 (s, C-30), 28.11 (s,
In Situ Synthesis of 5a and 6a: A solution of 4a (0.02 mmol) in C-27), 30.48 (s, C-26), 34.97 (s, C-31), 37.23 (s, C-24), 55.79 (s, C-
1
[D4]MeOH (2 mL) prepared as described above was transferred
into a 10 mm HPNMR tube under nitrogen at room temperature.
The tube was then charged with a (1:9) 13CO/12CO mixture to a
pressure of 200 psi. Analysis by multinuclear NMR spectroscopy
32), 69.92 (d, JC,P = 54.8 Hz, C-1) (C-2 overlapped), 71.31 (s, C-
3
6–C-10), 72.99 (d, JC,P = 6.3 Hz, C-4), 73.98 (s, C-3), 74.54 (d,
2JC,P = 7.2 Hz, C-5), 82.75 (s, C-25), 122.02 (d, JC,P = 7.8 Hz, C-
2
28), 124.11 (d, 2JC,P = 9.4 Hz, C-29), 128.77 and 129.02 (d; JC,P
=
3
Eur. J. Inorg. Chem. 2008, 441–452
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
449

ˇ
W. Oberhauser, P. Steˇpnicˇka et al.
FULL PAPER
10.6 Hz; C-14, C-16, C-20 and C-22), 129.6 (d, 1JC,P = 58.5 Hz, C- (d, JP,C = 5.6 Hz, C-4) (C-1 partially overlapped), 71.79 (d, JP,C
3
3
12 and C-18), 131.37 and 131.70 (d; 4JC,P = 1.5 and 2.1 Hz, respec-
tively; C-15 and C-21), 132.17 and 134.17 (d; JC,P = 11.9 and
= 5.6 Hz, C-3), 74.81 (d, 2JP,C = 7.8 Hz, C-5), 80.57 (s, C-25), 89.19
2
2
2
(d, JP,C = 20.0 Hz, C-2), 127.99 (d, JP,C = 7.4 Hz, C-30), 128.44
12.2 Hz, respectively; C-13, C-17, C-19 and C-23), 172.05 (s, C-11) (d; 3JP,C = 10.7 Hz; C-15, C-17, C-21 and C-23), 130.43 and 131.07
ppm. 31P{1H} NMR (161.98 MHz, CD2Cl2, 25 °C): δ = 16.79 ppm.
(d; JP,C = 1.9 and 1.5 Hz, respectively; C-16 and C-22), 130.61 (d,
1JP,C = 50.0 Hz, C-13 and C-19), 133.16 and 134.13 (d; 2JP,C = 12.2
and 12.6 Hz, respectively; C-14, C-18, C-20 and C-24), 133.21 (d,
2JP,C = 8.9 Hz, C-31), 174.38 (s, C-12) ppm. 31P{1H} NMR
4
Synthesis of 1c: A procedure analogous to that described above for
1a that used HLc instead of HLa was employed to give 1c as an
orange crystalline solid. Yield 99.5 mg (74%). C33H35FeO3PPd
(672.6): calcd. C 58.93, H 5.20; found C 59.02, H 5.31. Dia-
stereoisomer ratio A/B
(400.13 MHz, CD2Cl2, 25 °C): δ = 1.80–2.85 (9 H; 25-H, 27-H, 28-
(161.98 MHz, CD2Cl2, 25 °C): δ = 18.32 ppm. Diasteroisomer B:
1H NMR (400.13 MHz, CD2Cl2, 25 °C): δ = 0.87 (t, JH,H
=
3
=
3:2. Diasteroisomer A: 1H NMR
7.0 Hz, 3 H, 36-H), 1.11 (dd, 2JH,H = 7.2 and JH,H = 1.2 Hz, 1 H,
3
2
3
29-H), 1.38 (dd, JH,H = 9.9 and JH,H = 1.6 Hz, 1 H, 29Ј-H), 1.86
(m, 2 H, 32-H), 2.38 (d, 2JH,H = 5.5 Hz, 33-H), 2.70–2.92 (5 H; 11-
H, 28-H and 34-H), 2.92–3.02 (2 H, 26-H and 27-H), 3.15 (m, 1
H, 35-H), 3.36 (m, 1 H, 35Ј-H), 3.61 (m, 1 H, 25-H), 3.74 (m, 1 H,
2
H, 31-H and 32-H), 2.58 (s, 3 H, 33-H), 3.22 (d, JH,H = 12.7 Hz,
2
1 H, 11-H), 3.66 (d, JH,H = 12.7 Hz, 1 H, 11Ј-H), 3.89 (s, 5 H, 6-
H–10-H), 4.02 (m, 1 H, 4-H), 4.34 (m, 1 H, 5-H), 4.55 (m, 1 H, 3-
H), 6.16 (m 1 H, 30-H), 6.77 (m, 1 H, 29-H), 7.24–8.20 (m, overlap-
ping signals, 14-H–18-H and 20-H–24-H) ppm. 13C{1H} NMR
(100.62 MHz, CD2Cl2, 25 °C): δ = 25.09 (s, C-31), 28.09 (s, C-28),
30.93 (s, C-27), 35.76 (s, C-32), 39.34 (s, C-11), 42.82 (s, C-25),
3
3-H), 4.04 (s, 5 H, 6-H–10-H), 4.29 (t, JH,H = 2.4 Hz, 1 H, 4-H),
4.55 (m, 1 H, 5-H), 6.69 (m, 1 H, 31-H), 7.10 (m, 1 H, 30-H), 7.45–
7.98 (m, overlapping signals, 14-H–18-H and 20-H–24-H) ppm.
13C{1H} NMR (100.62 MHz, CD2Cl2, 25 °C): δ = 15.23 (s, C-36),
31.95 (s, C-34), 35.47 (s, C-29), 39.15 (s, C-27), 39.29 (s, C-11),
41.22 (s, C-33), 51.17 (s, C-32), 53.0 (s, C-26), 57.27 (s, C-28), 63.49
(s, C-35), 68.91 (d, JP,C = 5.7 Hz, C-4), 70.05 (C-1, partially over-
lapped), 70.70 (br, C-3), 74.34 (d, JP,C = 8.2 Hz, C-5), 81.30 (s, C-
25), 89.35 (d, JP,C = 20 Hz, C-2), 126.03 (d, JP,C = 7.2 Hz, C-30),
128.16 and 128.27 (d; JP,C = 10.7 and 11.5 Hz, respectively; C-15,
2
1
55.73 (s, C-33), 69.33 (d, JC,P = 5.2 Hz, C-5), 70.18 (d, JC,P
=
=
3
51.1 Hz, C-1), 70.44 (s, C-4), 71.07 (s, C-6–C-10), 74.75 (d, JC,P
8.5 Hz, C-3), 81.37 (s, C-26), 89.54 (d, 2JC,P = 18.9 Hz, C-2), 121.39
3
2
2
(d, JC,P = 7.6 Hz, C-30), 124.55 (d, JC,P = 9.7 Hz, C-29), 128.34
2
3
and 128.92 (d; JC,P = 9.9 and 11.6 Hz, respectively; C-15, C-17,
2
2
C-21 and C-23), 129.70 and 131.84 (d, 1JC,P = 1.5 Hz, C-16 and C-
3
1
22), 130.98 and 133.45 (d; JC,P = 51.5 and 48.1 Hz, respectively;
C-13 and C-19), 131.87 and 135.64 (d; JC,P = 14.4 Hz; C-14, C-
4
C-17, C-21 and C-23), 130.02 and 131.15 (d, JP,C = 1.5 Hz, C-16
2
1
and C-22), 130.61 (d, JP,C = 50.0 Hz, C-13 and C-19), 132.40 (d,
18, C-20 and C-24), 175.09 (s, C-12) ppm. 31P{1H} NMR
(161.98 MHz, CD2Cl2, 25 °C): δ = 15.52 ppm. Diasteroisomer B:
1H NMR (400.13 MHz, CD2Cl2, 25 °C): δ = 1.80–2.85 (9 H; 25-
H, 27-H, 28-H, 31-H and 32-H), 2.59 (s, 3 H, 33-H), 3.01 (d, 2JH,H
2JP,C = 8.9 Hz, C-31), 133.09 and 134.78 (d; JP,C = 11.5 and
2
13.3 Hz, respectively; C-14, C-18, C-20 and C-24), 174.63 (s, C-12)
ppm. 31P{1H} NMR (161.98 MHz, CD2Cl2, 25 °C): δ = 16.84 ppm.
2
= 13.1 Hz, 1 H, 11-H), 3.11 (d, JH,H = 13.1 Hz, 1 H, 11Ј-H), 4.02
Synthesis of 1d: A procedure analogous to that described above for
1a that used HLd instead of HLa was employed to give 1d as
orange microcrystals. Yield 151.3 mg (75%). C33H35FeO3PPd
(672.6): calcd. C 58.93, H 5.20; found C 59.05, H 5.41. Dia-
(m, 1 H, 4-H), 4.21 (s, 5 H, 6-H–10-H), 4.34 (m, 1 H, 5-H), 4.52
(m, 1 H, 3-H), 6.43 (m, 1 H, 30-H), 6.61 (m, 1 H, 29-H), 7.24–8.20
(m, overlapping signals, 14-H–18-H and 20-H–24-H) ppm.
13C{1H} NMR (100.62 MHz, CD2Cl2, 25 °C): δ = 25.30 (s, C-31),
28.57 (s, C-28), 31.37 (s, C-27), 35.22 (s, C-32), 38.02 (s, C-11),
40.48 (s, C-25), 55.40 (s, C-33), 68.64 (d, 2JC,P = 5.6 Hz, C-5), 71.25
stereoisomer ratio A/B
=
4:3. Diasteroisomer A: 1H NMR
(400.13 MHz, CD2Cl2, 25 °C): δ = 1.68–2.68 (9 H, 25-H, 27-H, 28-
2
H, 31-H and 32-H), 2.71 (s, 3 H, 33-H), 3.14 (dd, JH,P = 14.4 and
3
(s, C-6–C-10), 71.48 (s, C-4), 74.39 (d, JC,P = 8.5 Hz, C-3), 81.37
2JH,H = 12.8 Hz, 1 H, 11-H), 3.86 (br. s, 1 H, 5-H) (5-H, overlapped
(s, C-26), 89.02 (d, 2JC,P = 21.0 Hz, C-2), 122.16 (d, 2JC,P = 8.3 Hz,
C-30), 124.00 (d, 2JC,P = 8.5 Hz, C-29), 128.64 and 128.78 (d; 3JC,P
= 14.4 and 11.6 Hz, respectively; C-15, C-17, C-21 and C-23),
2
2
signal), 4.11 (s, 5 H, 6-H–10-H), 4.33 (dd, JH,P = 5.6 and JH,H
=
12.8 Hz, 1 H, 11Ј-H), 4.71 (br. s, 1 H, 3-H), 6.48 (m 1 H, 30-H),
(29-H, overlapped signal), 7.22–7.92 (m, 14-H–18-H and 20-H–24-
H) ppm. 13C{1H} NMR (100.62 MHz, CD2Cl2, 25 °C): δ = 25.28
4
130.85 and 131.12 (d, JC,P = 1.5 Hz, C-16 and C-22), 131.12 (d,
2
JC,P = 1.9 Hz, CHp PPh2), 133.36 and 133.70 (d; JC,P = 11.9 and
1
(s, C-31), 28.06 (s, C-28), 30.20 (s, C-27), 30.73 (d, JC,P = 22.9 Hz,
1
14.4 Hz, respectively; C-14, C-18, C-20 and C-24), 133.71 (d, JC,P
C-11), 35.60 (s, C-32), 38.89 (s, C-25), 55.83 (s, C-33), 67.42 (s, C-
3), 70.24 (s, C-6–C-10), 71.48 (s, C-4), 72.39 (s, C-5), 78.83 (d, 3JC,P
= 4.1 Hz, C-2), 81.86 (s, C-26) (C-1, overlapped signal), 122.37 (d,
= 46.3 Hz, C-13 and C-19), 175.09 (s, C-12) ppm. 31P{1H} NMR
(161.98 MHz, CD2Cl2, 25 °C): δ = 17.34 ppm.
2
Synthesis of 2c: A procedure analogous to that described above for
2a with HLc instead of HLa was employed to give 2c as an orange
crystalline solid. Yield 110.4 mg (74%). C36H37FeO3PPd (710.9):
calcd. C 60.85, H 5.21; found C 60.98, H 5.34. Diastereoisomer
ratio A/B = 3:1. Diasteroisomer A: 1H NMR (400.16 MHz,
2JC,P = 7.3 Hz, C-30), 124.57 (d, JC,P = 4.8 Hz, C-29), 128.67 and
3
3
128.03 (d; JC,P = 10.9 and JC,P = 9.7 Hz, respectively; C-15, C-
17, C-21 and C-23), 130.52 (br. s, C-16 and C-22), 131.40 and
134.80 (d; JC,P = 10.3 and 12.9 Hz, respectively; C-14, C-18, C-20
and C-24) (C-13 and C-19, overlapped signals), 176.29 (s, C-12)
ppm. 31P{1H} NMR (161.98 MHz, CD2Cl2, 25 °C): δ = 30.17 ppm.
Diasteroisomer B: 1H NMR (400.13 MHz, CD2Cl2, 25 °C): δ =
1.68–2.68 (9 H; 25-H, 27-H, 28-H, 31-H and 32-H), 2.41 (s, 3 H,
33-H), 3.30 (dd, 2JH,P = 14.4 and 2JH,H = 13.0 Hz, 1 H, 11-H), 3.96
2
3
CD2Cl2, 25 °C): δ = 1.05 (t, JH,H = 7.0 Hz, 3 H, 36-H), 1.18 (dd,
3
2
2JH,H = 7.2 and JH,H = 1.2 Hz, 1 H, 29-H), 1.37 (dd, JH,H = 9.9
3
and JH,H = 1.5 Hz, 1 H, 29Ј-H), 1.91 (m, 2 H, 32-H), 2.38 (d,
2JH,H = 5.5 Hz, 33-H), 2.70–2.92 (5 H, 11-H, 27-H and 34-H), 2.94
2
2
(m, 1 H, 28-H), 3.04 (m, 1 H, 26-H), 3.19 (m, 1 H, 35-H), 3.38 (m, (s, 1 H, 4-H), 4.03 (dd, JH,P = 7.4 and JH,H = 13.0 Hz, 1 H, 11Ј-
1 H, 35Ј-H), 3.52 (m, 1 H, 3-H), 3.61 (m, 1 H, 25-H), 4.12 (s, 5 H, H), 4.13 (s, 5 H, 6-H–10-H), 4.16 (br. s, 1 H, 5-H), 4.90 (br. s, 1 H,
6-H–10-H), 4.28 (t, 3JH,H = 2.5 Hz, 1 H, 4-H), 4.55 (m, 1 H, 5-H), 3-H), 6.26 (m, 1 H, 30-H) (29-H, overlapped signal), 7.22–7.92 (m,
6.55 (m, 1 H, 31-H), 7.57 (m, 1 H, 30-H), 7.35–7.75 (m, overlapping
signals, 14-H–18-H and 20-H–24-H) ppm. 13C{1H} NMR
(100.62 MHz, CD2Cl2, 25 °C): δ = 15.47 (s, C-36), 31.82 (s, C-34),
35.63 (s, C-29), 37.90 (s, C-27), 39.29 (s, C-11), 41.88 (s, C-33),
51.04 (s, C-32), 53.0 (s, C-26), 57.27 (s, C-28), 63.73 (s, C-35), 68.58
14-H–18-H and 20-H–24-H) ppm.13C{1H} NMR (100.62 MHz,
CD2Cl2, 25 °C): δ = 25.28 (s, C-31), 28.53 (s, C-28), 30.79 (s, C-
27), 31.34 (d, JP,C = 23.7 Hz, C-11), 35.15 (s, C-32), 38.35 (s, C-
1
25), 55.18 (s, C-33), 67.47 (s, C-3), 70.45 (s, C-6–C-10), 71.91 (s, C-
4), 72.89 (s, C-5), 78.84 (d, 3JC,P = 4.1 Hz, C-2), 81.69 (s, C-26) (C-
450
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 441–452

Semialternating CO–Ethylene Copolymerization
2
1, overlapped signal), 120.79 (d, JC,P = 7.3 Hz, C-30), 124.65 (d,
Crystal Structure Determination of 2c: X-ray diffraction intensity
data were collected at 150 K on an Oxford Diffraction CCD dif-
fractometer with graphite monochromated Mo-Kα radiation (λ =
0.71073 Å) using ω-scans. Cell refinement, data reduction and the
empirical absorption correction were carried out with the Oxford
diffraction software and SADABS.[18a] All structure determination
calculations were performed with the WINGX package[18b] with
SIR-97,[18c] SHELXL-97[18d] and ORTEP-3 programs.[18e] Final re-
finements based on F2 were carried out with anisotropic thermal
parameters for all non-hydrogen atoms, while the hydrogen atoms
were included in calculated positions and refined using a riding
model with isotropic Uiso(H) values dependent on the Ueq(C) of
the adjacent carbon atoms. The highest residual electron density of
1.7 eÅ–3 is located close to C(32), which shows a distance of
1.547 Å to this latter atom. The rather poor crystal quality of com-
pound 2c accounts for the observed residual electron density. Rel-
evant crystallographic data are summarized in Table 3.
2JC,P = 5.6 Hz, C-29), 128.39 and 129.27 (d; 3JC,P = 9.7 and10.3 Hz,
respectively; C-15, C-17, C-21 and C-23), 130.81 (br. s, C-16 and
C-22), 132.90 and 133.66 (d; 2JC,P = 10.3 and 12.9 Hz, respectively;
C-14, C-18, C-20 and C-24) (C-13 and C-19, overlapped signals),
176.29 (s, C-12) ppm. 31P{1H} NMR (161.98 MHz, CD2Cl2,
25 °C): δ = 30.25 ppm.
Operando HPNMR Experiments: To a solution of compound 4a
(13.5 mg, 0.02 mmol) in [D4]MeOH (2 mL) was added TsOH
(68.4 mg, 0.36 mmol). The acidic methanol solution was transfer-
red under nitrogen into a 10 mm sapphire tube that was placed into
an NMR probe head at room temperature, and the 31P{1H} and
1H NMR spectra were acquired at this same temperature. Then the
sapphire tube was removed from the NMR probe and charged with
CO (200 psi), and the 31P{1H} and 1H NMR spectra were acquired
again at room temperature. Afterwards, the sapphire tube was re-
moved from the NMR probe and charged with ethylene (600 psi)
at room temperature, before the 31P{1H} and 1H NMR spectra
were again acquired. Then the sapphire tube was heated in the
NMR probe from room temperature to 100 °C, while the 31P{1H}
and 1H NMR spectra were acquired at temperature intervals of
10 °C. Once the reaction temperature of 100 °C was reached, the
sapphire tube was continuously heated for half an hour, before the
31P{1H} and 1H NMR spectra were acquired. Then the sapphire
tube was cooled to room temperature, and the 31P{1H} and 1H
NMR spectra were again acquired. Afterwards, the sapphire tube
was removed from the NMR probe, the gases were vented off and
the reaction solution was analyzed by GC-MS.
Table 3. Crystallographic data and structure refinement details for
2c.
Formula
C36H37FeO3PPd
710.88
orange prism
0.6ϫ0.4ϫ0.2
150.0(2)
monoclinic
P21/n (no. 14)
15.425(5)
11.189(5)
17.980(5)
110.557(5)
2905.6(2)
4
Molecular weight [gmol–1]
Crystal habit
Crystal size [mm]
Temperature [K]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
Catalytic Copolymerization Reaction in MeOH: In a typical experi-
ment, MeOH (50 mL) was introduced into an autoclave (200 mL)
which had been previously evacuated by a vacuum pump and
charged with the catalyst precursor (0.012 mmol) and the desired
amounts of TsOH and/or BQ. Then, the autoclave was charged
with the appropriate CO/ethylene gas ratio to a total pressure of
400 psi at room temperature. The autoclave was then heated by
means of a silicon oil bath. Once the desired reaction temperature
was reached, the total pressure of the appropriate gas mixture was
adjusted to 800 psi, and stirring was started (1200 rpm). After the
desired reaction time, the autoclave was cooled by means of an ice-
water bath, and unreacted gases were vented off. The polymeric
material was filtered off, washed with MeOH (3ϫ20 mL) and dried
under vacuum at 50 °C until a constant weight was obtained.
β [°]
V [Å3]
Z
Density (calculated) [gcm–3]
F(000)
1.625
1456
θ range [°]
4.16–32.14
1.211
0.565–0.785
9406
9406
380
Absorption coefficient [mm–1]
Range of transmission factors
Reflections collected
Independent reflections
Parameters
Gof on F2
1.103
R1, wR2 [IϾ2σ(I)]
R1, wR2 (all data)
∆ρ [eÅ–3]
0.0797, 0.1375
0.1022, 0.1473
1.719/–1.168
Characterization of the Copolymers: The polyketone products were
analyzed by IR as well as H and 13C{1H} NMR spectroscopy.[7a]
1
The NMR measurements, performed in a 1:1 (v/v) mixture of [D2]-
HFIP and C6D6, showed an imperfectly alternating structure origi-
nating from double ethylene insertion. All of the polymer samples
featured ketone and ester end groups in a 1:1 molar ratio. The
number-average molecular weights (Mn) of the copolymers were
determined by 1H NMR spectroscopy, while the degree of extra-
ethylene insertion was determined by 13C NMR using an inverse-
gated decoupling pulse sequence. Typical analytical data: 1H NMR
CCDC-649696 contains the supplementary crystallographic data
for this paper. These data can be obtained free of charge from the
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
Acknowledgments
3
(400.13 MHz, 294K): δ = 0.82 [t, JH,H = 7.2 Hz, C(O)CH2CH3],
3
2.03 [q, JH,H = 7.2 Hz, C(O)CH2CH3], 2.38 [br. s, CH2C(O)CH2],
Thanks are due to the European Commission (STREP contract
no. NMP3-CT-2005-516972 – NANOHYBRID) and Ministero
3
[C(O)CH2CH2CH2CH2C(O), overlapped signal], 2.68 [t, JH,H
=
9.2 Hz, C(O)CH2CH2CH2CH2C(O)], 3.35 (s, OCH3) ppm. 13C{1H} dell’Istruzione, dell’Università e della Ricerca (Fondo per gli In-
NMR (100.62 MHz, 294K): δ = 6.71 [s, C(O)CH2CH3], 21.69 [s, vestimenti della Ricerca di Base
– FIRB, contract no.
C(O)CH2CH2CH2CH2C(O)], 35.27 [s, CH2C(O)CH2], 40.25 [s, RBNE03R78E – NANOPACK) and FISR project “Nanosistemi
C(O)CH2CH2CH2CH2C(O)], 51.62 (s, OCH3), 175.39 [s, C(O)- inorganici ed ibridi per lo sviluppo e l’innovazione di celle a com-
OCH3], 211.44 [s, CH2C(O)CH2], 212.52 [s, (CH2CH2)2C(O)- bustibile” for financial support. This study is a part of the long-
CH CH ], 215.07 [s, C(O)CH CH ] ppm. IR (KBr): ν = 3392 (w),
term research projects supported by the Czech Ministry of Educa-
˜
2
2
2
3
2911 (m), 1695 (vs), 1407 (s), 1334 (s), 1258 (m), 1197 (w), 1175 tion, Youth and Sports (project nos. MSM0021620857 and
(w), 1056 (s), 810 (m), 592 (m) cm–1.
LC06070).
Eur. J. Inorg. Chem. 2008, 441–452
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Received: August 31, 2007
Published Online: November 23, 2007
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Eur. J. Inorg. Chem. 2008, 441–452