Phosphazene-functionalized cyclopentadienyl and its derivatives ligated rare-earth metal alkyl complexes: Synthesis, structures, and catalysis on ethylene polymerization

Article abstract of DOI:10.1021/om300263p

Treatment of Ln(CH₂SiMe₃)₃(thf) ₂ (Ln = Sc, Y, and Lu) with 1 equiv of CpPN-type ligands C ₅H₄=PPh₂-NH-C₆H₃R ₂ (R = Me, L¹(Me); R =

Full text of DOI:10.1021/om300263p

Article
pubs.acs.org/Organometallics
Phosphazene-Functionalized Cyclopentadienyl and Its Derivatives
Ligated Rare-Earth Metal Alkyl Complexes: Synthesis, Structures, and
Catalysis on Ethylene Polymerization
Zhongbao Jian,†,‡,⊥ Alex R. Petrov,§,⊥ Noa K. Hangaly,§ Shihui Li,† Weifeng Rong,†,‡ Zehuai Mou,†,‡
Konstantin A. Rufanov,§,∥ Klaus Harms,§ Jorg Sundermeyer,*,§ and Dongmei Cui*,†
̈
†State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences,
Changchun 130022, China
‡Graduate School of the Chinese Academy of Sciences, Beijing 100039, China
§Fachbereich Chemie der Philipps-Universitat Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
̈
∥Department of Chemistry, M. V. Lomonosov University of Moscow, 119992, Moscow, Russia
S
* Supporting Information
ABSTRACT: Treatment of Ln(CH2SiMe3)3(thf)2 (Ln = Sc, Y, and Lu) with 1 equiv of CpPN-type ligands C5H4PPh2−NH−
i
C6H3R2 (R = Me, L1(Me); R = Pr, L1(iPr)) at room temperature readily generated the corresponding CpPN-type bis(alkyl)
complexes 1 and 2a−2c. Addition of 3 equiv of LiCH2SiMe3 to a mixture of L1(iPr) and LnCl3(thf)2 (Ln = Sm and Nd) also
afforded the CpPN-type bis(alkyl) complexes 2d and 2e. The Cp moiety bonds to the central metal in a classical η5 mode in all
CpPN-type complexes 1 and 2. In contrast, the CpMePN-type ligands C5Me4H−PPh2N−C6H3R2 (R = Me, L2(Me); R = iPr,
L2(iPr)) behaved differently. L2(Me) did not react with Sc(CH2SiMe3)3(thf)2. Similarly, L2(iPr) was also inert to
Sc(CH2SiMe3)3(thf)2 even at 50 °C. When the central metal was changed to yttrium, however, the equimolar reaction
between Y(CH2SiMe3)3(thf)2 and L2(iPr) in the presence of LiCl afforded two bis(alkyl) complexes 3a and 3b. In the main
product 3a, [C5HMe3(η3-CH2)−PPh2N−C6H3 Pr2]Y(CH2SiMe3)2(thf), the ligand bonds to the Y3+ ion in a rare η3-allyl/κ-N
i
i
mode, whereas in 3b, (C5Me4−PPh2N−C6H3 Pr2)Y(CH2SiMe3)2(LiCl)(thf), the Cp ring coordinates to the Y3+ ion in an η5
mode, and a LiCl unit is located between the Y3+ ion and the nitrogen atom. When the central metal was changed to lutetium, a
i
bis(alkyl) complex 4a, [C5HMe3(η3-CH2)−PPh2N−C6H3 Pr2]Lu(CH2SiMe3)2(thf), and a bis(alkyl) complex 4b, (C5Me4−
i
PPh2N−C6H3 Pr2)Lu(CH2SiMe3)2, were isolated. The protonolysis reaction of the IndPN-type ligands C9H7−PPh2N−
i
C6H3R2 (R = Me, L3(Me); R = Et, L3(Et); R = Pr, L3(iPr)) with Ln(CH2SiMe3)3(thf)2 (Ln = Sc, Y, and Lu) generated the
IndPN-type bis(alkyl) complexes 5a−5c, 6, and 7a−7c, selectively, where the Ind moiety tends to adopt an η3-bonding fashion.
The more bulky FluPN-type ligands C13H9−PPh2N−C6H4R (R = H, L4(H); R = Me, L4(Me)) were treated with
Ln(CH2SiMe3)3(thf)2 (Ln = Sc and Lu) to afford the FluPN-type bis(alkyl) complexes 8 and 9a and 9b, where the Flu moiety
has a rare η1-bonding mode. Complexes 1−9 were fully characterized by 1H, 13C, and 31P NMR; X-ray; and elemental analyses.
Upon activation with AlR3 and [Ph3C][B(C6F5)4], the scandium complexes showed good to high catalytic activity for ethylene
polymerization. The effects of the sterics and electronics of the ligand, the loading and the type of AlR3, the polymerization
temperature, and the polymerization time on the catalytic activity were also discussed.
interesting chemical structures and unique reactivities but also
showed versatile catalytic activity and selectivity in the
polymerizations of olefins or conjugated dienes.1 In the rapid
INTRODUCTION
■
In the past decades, as the most commonly used ligands in the
field of organometallic chemistry and polymerization, cyclo-
pentadienyl (Cp), substituted Cp, and the indenyl (Ind) and
fluorenyl (Flu) ligands have attracted considerable interest,
because their related metal complexes not only exhibited
Received: March 30, 2012
Published: May 18, 2012
© 2012 American Chemical Society
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development of Cp-based complexes, to tune the steric and
electronic properties around the central metal and control the
orientation and rotation of the Cp-type ring, variation of the Cp
substitution pattern has been extensively investigated. Introduc-
ing a soft or rigid heteroatom side arm on the Cp ring to form a
constrained-geometry mode around the central metal is an
efficient and tempting approach. Constrained-geometry com-
plexes (CGCs), as one of the best developed classes of Cp-
based complexes, were first reported by Bercaw and Okuda by
using the dianionic cyclopentadienyl-silylamido (CpSiN)
ligands, which showed excellent activity and selectivity toward
olefin polymerization.2−4 Since this breakthrough, by changing
the nature of the Cp moieties,5 the bridging units (soft or
hard),6 and the donating heteroatom types on the side arm,7
various metal complexes based on monoanionic or dianionic
CGC ligands have been extensively synthesized and have their
reactivities investigated. In particular, as the isolobal analogue of
the classical CpSiN-type ligands, the monoanionic phospha-
zene-functionalized cyclopentadienyl (CpPN) ligands have
attracted increasing attention, owing to swift modification of
their electronic properties and bulkiness by varying the
substituents at the N and P atoms and Cp ring. Since 2005,
we have presented the synthesis of some CpPN ligands and
corresponding group 4 and rare-earth metal complexes by
focusing mainly on the C5Me4PMe2−NH−Ad (Ad = 1-
adamantyl) ligand.8 The monoanionic IndPN- and FluPN-type
ligand-attached rhodium and zirconium complexes have been
also reported by Bourissou and co-workers.9 However, to date,
the study of the organometallic chemistry and polymerization
of rare-earth metal CpPN, IndPN, and FluPN complexes is very
limited, but promising, and needs to be further explored.
On the other hand, polyethylene (PE), which is the largest
volume synthetic polymer applied in every aspect of our daily
lives, such as packaging materials, pipes, textiles, etc., has been
extensively studied in both academic and industrial fields. To
date, catalyst systems for ethylene polymerization are mostly
focused on transition metals or late transition metals,10 those
based on rare-earth metals are relatively explored less.11 So far,
both non-Cp,12 such as N-type amino and imino ligands, and
mono-Cp (or its derivatives)13 attached rare-earth metal
complexes, especially the scandium complexes, have been
reported to initiate the polymerization of ethylene with good
activity, although the scandium remains a model and may be
difficult to apply in ethylene polymerization due to its
prohibitive cost. Comparatively, the catalyst precursors based
on CGC ligands that can polymerize ethylene were extremely
limited, as far as we are aware.6g,14
Chart 1. Rare-Earth Metal Complexes Containing Various
Nitrogen-Modified Cp Ligands
phosphazene side arm can enforce and modulate the low
hapticity of Ind and Flu. The detailed study of ethylene
polymerization shows that the scandium precursors provide the
highest activity.
RESULTS AND DISCUSSION
Preparation of the CpPN-type Bis(alkyl) Complexes 1
■
and 2a−2e. We first focused on the less sterically crowded
i
CpPN-type ligands. The ligand C5H4PPh2−NH−C6H3 Pr2
(L1(iPr)) synthesis via TlC5H4 and PPh2Cl followed by a
Staudinger reaction was reported by us.8d Herein, we
successfully exchanged the highly toxic TlC5H5 with NaC5H5,
which can be easily obtained from Na and dicyclopentadiene.
The improved ligand synthesis, which is readily synthesized on
a large scale using cheap starting materials, makes the CpPN-
type ligand much more attractive. Therefore, the ligands
C5H4PPh2−NH−C6H3R2 (R = Me, L1(Me); R = Pr,
i
L1(iPr)) were prepared via NaC5H5 and PPh2Cl, followed by
a Staudinger reaction with 1.5 equiv of C6H3R2N3 in 83% and
63% yields, respectively (Scheme 1). The 1H NMR spectrum of
Scheme 1. Synthesis of the CpPN-type Ligands L1(Me) and
L1(iPr)
L1(Me) shows a doublet at δ = 4.40 ppm with a coupling
constant (2JPH = 6.0 Hz) arising from the NH proton, but no
allylic ring proton (CpH) is observed. In addition, the 31P
NMR resonance of L1(Me) (25.1 ppm) is similar to the
chemical shift of compound L1(iPr) (28.9 ppm).8d The NMR
spectroscopy suggests that L1(Me), like L1(iPr), preferentially
exists in its thermodynamically more favorable form of a P-
amino-cyclopentadienyl-phosphorane (type I, Chart 2). The
NH amino proton is of relative high kinetic acidity; therefore,
ligands L1(Me) and L1(iPr) can readily react with 1 equiv of
Ln(CH2SiMe3)3(thf)2 (Ln = Sc, Y, and Lu) at room
temperature to straightforwardly generate the desired CpPN-
type bis(alkyl) complexes 1 and 2a−2c in high isolated yields
(57−71%) (Scheme 2). In addition, it is well known that only a
few rare-earth metal tris-alkyl precursors are of sufficient
thermal stability.1b Therefore, we have used an alternative
synthetic protocol to prepare the samarium and neodymium
complexes.15 Addition of 3 equiv of LiCH2SiMe3 to a mixture
Recently, we became interested in rare-earth metal
complexes based on the monoanionic nitrogen-functionalized
Cp ligands, and we have reported a series of rare-earth metal
complexes based on aminophenyl-CpMe and pyridyl-CpMe
ligands (Chart 1), which showed excellent reactivities and
polymerization performances toward dienes and styrene
monomers.6a−f In this contribution, therefore, we select a
series of phosphazene-functionalized cyclopentadienyl (CpPN),
tetramethylcyclopentadienyl (CpMePN), indenyl (IndPN), and
fluorenyl (FluPN) compounds as the monoanionic ancillary
ligands. The synthesis and the detailed characterization and the
diverse and interesting structures of a new family of rare-earth
metal bis(alkyl) complexes are presented. More remarkably, we
will demonstrate the strong influences of the central metals, the
substituents at nitrogen, and the substituents on the Cp ring on
the protonolysis reaction, while we also find that the pendent
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field in comparison with the free ligand (L1(Me): δ = 25.12
ppm; L1(iPr): δ = 28.9 ppm).8d Furthermore, X-ray studies of 1
and 2a−2e reveal that the Cp ring coordinates to the metal
center in a typical η5 mode (Figures 1 and 2). In all structures,
Chart 2. Preferred Tautomer of Different CpPN-type
Ligands
Scheme 2. Synthesis of the CpPN-type Complexes 1 and 2a−
2c
Figure 1. X-ray structure of 1 (40% probability of thermal ellipsoids).
Hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and
angles (deg): Sc1−Cpcent 2.251, Sc1−C26 2.212(3), Sc1−C30
2.219(2), P1−C1 1.769(2), P1−N1 1.623(2), Sc1−N1 2.188(2);
C1−P1−N1 99.2(1), Cpcent−Sc1−N1 95.9, C26−Sc1−C30 102.9(1)
(CpCent is the centroid of the cyclopentadienyl ring).
of L1(iPr) and LnCl3(thf)2 (Ln = Sm and Nd) at 0 °C readily
afforded the CpPN-type bis(alkyl) complexes 2d and 2e
(Scheme 3). Complexes 1 and 2a−2e were fully characterized
Scheme 3. Synthesis of the CpPN-type Complexes 2d and 2e
the P−C1 bond lengths (1.757(4)−1.769(2) Å) are clearly
longer than those in the L1(iPr) ligand (1.718(1) Å); however,
the P1−N1 bond distances (1.590(5)−1.625(3) Å) are shorter
than those in the ligand (1.649(1) Å).8d Additionally, we
observe that the Sc1−N1 bond distances (2.188(2)−2.214(3)
Å) are comparable to those in NPN-type scandium complexes
(2.175−2.203 Å).16
Noteworthy is that they are longer than the covalent Sc−N
bond in the CpSiN-type complexes (2.071(6)−2.083(5) Å),2d
but shorter than the coordination Sc−N bond (up to 2.47
Å).6a,b,f,g,12a These results suggest that the electrons in the
complexes tend to delocalize within the N−P−Cp fragment.
Despite the large difference in ionic radii of the central metals,
the molecular structures of 2b, 2d, and 2e are very similar
(Figure 2). The notable structural feature is the larger Ln−N
bond lengths in 2b (2.469(3) Å), 2d (2.533(6) Å), and 2e
(2.572(2) Å) compared with the analogous complexes η5,η1-
C5Me4PMe2NAdLn(CH2SiMe3)2 (Y: 2.316(4) Å, Sm: 2.367(3)
Å),8b demonstrating the lower basicity of L1(iPr) in comparison
with the C5Me4PMe2NHAd ligand. A consequence is the
presence of a coordinated THF molecule. The most interesting
feature in the structures of 2b, 2d, and 2e is the rather small
Cpcent−Ln−N bite angles of 87.2(1), 85.2(1), and 85.0(1)°,
respectively, which explains the coordination of the additional
THF molecule.
by multinuclear NMR spectroscopy (1H, 13C, and 31P), X-ray
diffraction, and elemental analysis. The H NMR spectra of
1
scandium complexes 1 and 2a exhibit a doublet at δ = 0.09 ppm
and a broad singlet at δ = 0.20 ppm assigned to the Sc−
CH2SiMe3 methylene protons, respectively. No THF coordi-
nation molecule is observed, which is unambiguously confirmed
by the X-ray diffraction study as well. In contrast, the 1H NMR
spectra suggest that 2b−2e with larger ionic radii contain one
THF molecule in the structure, which is different from the
THF-free rare -e arth me tal complexes η5 , η1 -
C5Me4PMe2NAdLn(CH2SiMe3)2 (Ln has a bigger ionic radii,
such as Pr and Ce) reported previously by us.8a,b We conclude
that the less steric bulkiness of the Cp-ring leads to the
coordination of THF. The yttrium and lutetium complexes 2b
1
1
and 2c show the clear and similar H NMR spectra. The H
NMR spectra of paramagnetic samarium and neodymium
complexes 2d and 2e show some broad and some sharp signals.
In addition, single sharp resonances with the chemical shifts of
δ = 7.8, 11.1, 10.1, and 10.4 ppm in the 31P NMR spectra refer
to 1 and 2a−2c, respectively, whereas 31P NMR spectra of
paramagnetic samarium and neodymium complexes 2d and 2e
show broad signals at δ = 18.1 and −62.8 ppm, respectively.
These resonances are in a good agreement with those found in
η5,η1-C5Me4PMe2NAdLn(CH2SiMe3)2,8a,b but are shifted up-
Preparation of the CpMePN-type Bis(alkyl) Complexes
3a, 3b and 4a, 4b. We have found that the structures of
CpPN-type ligands exist either in their P-amino-cyclopentadie-
nylidene-phosphorane (I-type, Chart 2) or in their P-cyclo-
pentadienyl-iminophosphorane tautomeric form (II- and III-
types, Chart 2).8 The equilibrium between both tautomers
strongly depends on the substituents at the N, P, and C(Cp)
atoms as they influence the relative Brønsted acidity of the Cp−
H and RN−H protons.8d For example, ligands L1(Me) and
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Figure 2. X-ray structures of 2a, 2b, 2d, and 2e (40% probability of thermal ellipsoids). Hydrogen atoms are omitted for clarity. Selected bond
lengths (Å) and angles (deg): 2a: Sc1−Cpcent 2.260, Sc1−C30 2.180(5), Sc1−C34 2.266(6), P1−C1 1.768(4), P1−N1 1.625(3), Sc1−N1 2.214(3);
C1−P1−N1 99.0(2), Cpcent−Sc1−N1 95.3, C34−Sc1−C30 103.1(2). 2b: Y1−Cpcent 2.460, Y1−C30 2.421(4), Y1−C34 2.419(4), P1−C1 1.757(4),
P1−N1 1.611(3), Y1−O1 2.448(3), Y1−N1 2.469(3); Cpcent−Y1−N1 87.2(1), C30−Y1−C34 109.7(1). 2d: Sm1−Cpcent 2.516, Sm1−C30
2.477(7), Sm1−C34 2.482(7), P1−C1 1.758(8), P1−N1 1.590(5), Sm1−O1 2.491(4), Sm1−N1 2.533(6); Cpcent−Sm1−N1 85.2(1), C30−Sm1−
C34 110.6(3). 2e: Nd1−Cpcent 2.551, Nd1−C30 2.498(2), Nd1−C34 2.504(3), P1−C1 1.767(3), P1−N1 1.608(2), Nd1−O1 2.543(2), Nd1−N1
2.572(2); Cpcent−Nd1−N1 85.0(1), C30−Nd1−C34 110.2(1).
L1(iPr) occur in the form of tautomer I, C5H4PPh2−NH−Ar
(Chart 2). Allylic iminophosphorane (type II) C5Me4H−
in the 31P NMR spectrum is in the region of iminophosphor-
anes but is still shifted upfield (δ = −15.07 ppm for L2(iPr)) in
comparison with the singlet at δ = −3.1 ppm for the II-type
i
PMe2N−C6H3 Pr2 was observed as a product of kinetic
C5Me4H−PMe2N−C6H3 Pr2 ligand.8d X-ray diffraction study
i
control, which, upon prolonged heating under thermodynamic
control, can rearrange to the III-type product. The new
CpMePN ligands C5Me4H−PPh2N−C6H3R2 (R = Me,
further confirms that the ligands exist as the III-type (Figure 3).
The bond lengths of C1−C2 (1.350(3) Å) and C3−C4
(1.336(4) Å) are much shorter than the bond lengths of C1−
C5 (1.512(3) Å), C2−C3 (1.474(4) Å), and C4−C5 (1.498(4)
Å), showing the nature of the double bond. In addition, C6
obviously deviates from the Cp (C1−C5) plane by 1.169 Å,
suggesting that C5 is a sp3-hybridized carbon atom. Because of
the special position of the H proton in the L2(Me) and L2(iPr)
ligands, we became interested in their reaction chemistry and
expected to give access to some novel structures. We first
investigated the reactivity of the L2(Me) ligand. To our
surprise, compared with the good reactivity of the L1(Me)
ligand, reaction of 1 equiv of L2(Me) with Sc-
(CH2SiMe3)3(thf)2 at room temperature or higher (50 °C)
i
L2(Me); R = Pr, L2(iPr)) synthesized through prolonged
heating of rather unreactive C5Me4H−PPh2 with ArN3 occur in
the thermodynamically most favorable form of type III, which
1
has a weak reactivity. In the H NMR spectra of L2(Me) and
L2(iPr), a quartet signal is observed at δ = 3.11−3.14 ppm and
δ = 3.10−3.13 ppm assigned to the C5Me4H proton,
respectively, which is completely different from the doublet
signal at δ = 3.37 ppm with a 2JPH coupling constant (26.8 Hz)
assigned to the C5Me4H proton in the II-type C5Me4H−
PMe2N−C6H3 Pr2 ligand.8d Because of the absence of
i
symmetry in both ligands, one doublet and three singlets are
observed for the C5Me4 groups. Moreover, the resonance signal
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that the reactive H proton of L2(Me) is a weaker acidic proton
compared with the NH proton of L1(Me) and is shielded by
neighboring groups, while the Sc(CH2SiMe3)3(thf)2 is of
weaker reactivity than the Y(CH2SiMe3)3(thf)2 and Lu-
(CH2SiMe3)3(thf)2, both of which lead to no reaction between
L2(Me) and Sc(CH2SiMe3)3(thf)2. Changing the C6H3Me2
i
substituent at the nitrogen atom to the more bulky C6H3 Pr2,
some interesting reactions took place, which were strongly
dependent on the type of central metals. Although the reaction
of Sc(CH2SiMe3)3(thf)2 and the L2(iPr) ligand did not take
place as well (Scheme 5), L2(iPr) reacted with Y-
(CH2SiMe3)3(thf)2 in the presence of LiCl to rapidly afford
1
two bis(alkyl) products 3a and 3b, evidenced by the H and
13C NMR spectra (Scheme 5). The main product 3a could first
deposit from a toluene/hexane mixture as yellow crystalline
solids, and then the remaining mother liquor afforded further
crystals of complexes 3a and 3b when cooling to −30 °C for 2
1
days. In the H NMR spectrum of 3a, an AB spin system is
Figure 3. X-ray structure of the ligand L2(iPr) (40% probability of
thermal ellipsoids). Hydrogen atoms are partly omitted for clarity.
Selected bond lengths (Å) and angles (deg): C1−C2 1.350(3), C3−
C4 1.336(4), C1−C5 1.512(3), C2−C3 1.474(4), C4−C5 1.498(4),
C1−P1 1.793(2), P1−N1 1.562(2); C1−P1−N1 116.5(1), C1−C5−
C4 102.6(2).
observed at δ = −0.30 and −0.50 ppm, which can be attributed
to the Y−CH2SiMe3 methylene protons. To our surprise,
however, two singlets appearing at δ = 4.28 and 4.51 ppm in a
1:1 ratio, which correlate with the singlet at δ = 73.25 ppm (JYC
is not observed) in the 13C NMR spectrum,6a,b may arise from
the newly generated methylene (CH2) protons. Meanwhile, a
quartet is still found at δ = 3.27−3.30 ppm (13C: δ = 52.98
ppm) assigned to the CpH proton according to the NMR
information of L2(iPr) ligand. Consistently with these, there are
signals attributable to three, rather than four, methyl groups on
the Cp ring. To the best of our knowledge, these data could
reveal that a hydrogen proton on the allylic methyl group rather
than on the Cp ring was abstracted in the C−H bond activation
reaction. Such unique behavior has been accidentally observed
by us in a yttrium byproduct (η5:κ-C5Me4−C5H4N)-
[C5HMe3(η3-CH2)−C5H4N-κ]Y(CH2SiMe3).6b The interest-
ing NMR spectra of 3a inspired us to study its structure, which
was successfully resolved by X-ray diffraction to be an unusual
1
did not give the desired product (Scheme 4). The H NMR
spectrum also showed that no reaction happened. We conclude
Scheme 4. Unsuccessful Synthesis of the CpMePN-type
Complexes
[C5HMe3(η3-CH2)−PPh2N−C6H3 Pr2]Y(CH2SiMe3)2(thf)
i
(Figure 4). The CpMePN-type ligand bonds to the Y3+ ion in a
rare κ-N/η3-allylic mode. The C1−C5 (1.442(4) Å) and C5−
C6 (1.369(4) Å) interatomic distances that form part of the
allyl component bound to yttrium are not as similar as these
Scheme 5. Synthesis of the CpMePN-type Complexes 3a, 3b and 4a, 4b
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ligand-alkaline salts with rare-earth metal trichlorides and then
with 2 equiv of alkyl lithium, (ii) the rare-earth metal
trichlorides with 3 equiv of alkyl lithium (some rare-earth
metal tris(alkyl)s are unstable and cannot be isolated) and then
with the neutral ligand, and (iii) the alkyl abstraction of stable
rare-earth metal tris(alkyl)s with the neutral ligand.19 Yao and
co-workers obtained the “Li”- and “Cl”-containing product
{[ONNO]Gd(CH2SiMe3)(μ-Li)(μ-Cl)}2 by using the (ii)
method.19b Herein, in the presence of LiCl, we used the (iii)
method to prepare the yttrium bis(alkyl) 3b. The structure of
i
3b, (C5Me4−PPh2N−C6H3 Pr2)Y(CH2SiMe3)2(LiCl)(thf),
was evidenced by X-ray diffraction (Figure 5). The LiCl unit,
Figure 4. X-ray structure of 3a (40% probability of thermal ellipsoids).
Hydrogen atoms are partly omitted for clarity. Selected bond lengths
(Å) and angles (deg): C1−C5 1.442(4), C5−C6 1.369(4), C1−C2
1.527(4), C2−C3 1.512(4), C3−C4 1.336(5), C4−C5 1.484(4), P1−
C1 1.739(3), P1−N1 1.623(2), Y1−C1 2.749(3), Y1−C5 2.669(3),
Y1−C6 2.724(3), Y1−N1 2.383(2), Y1−O1 2.388(2), Y1−C34
2.407(3), Y1−C38 2.408(4); C1−C5−C6 129.9(3), C1−P1−N1
106.2(1), C34−Y1−C38 103.4(2).
analogous distances, 1.391(3) and 1.392(3) Å, in (C5Me5)2Y-
(η3-C3H5),17 and 1.412(4) and 1.404(4) Å, in (η5:κ-C5Me4−
C5H4N)[C5HMe3(η3-CH2)−C5H4N-κ]Y(CH2SiMe3),6b but
being comparable to the corresponding bond lengths in
(C5Me5)Y(η5-C5Me4CH2−C5Me4CH2-η3) (1.380(2) and
1.434(2) Å).18 In particular, the Y1−C(allyl) distances tend
to be equal (2.749(3), 2.669(3), and 2.724(3) Å), which are
similar to the close Y−C(allyl) distances (2.582(2), 2.582(2),
and 2.601(2) Å) in (C5Me5)2Y(η3-C3H5),17 but different
significantly from those Y−C(allyl) distances in (η5:κ-
C5Me4−C5H4N)[C5HMe3(η3-CH2)−C5H4N-κ]Y(CH2SiMe3)
(2.961(3), 2.792(3), and 2.501(3) Å)6b and (C5Me5)Y(η5-
C5Me4CH2−C5Me4CH2-η3) ((2.990(2), 2.699(2), and
2.450(2) Å)),18 suggesting that the Y1−C(η3-allyl) linkage in
3a is almost symmetric. In addition, the P1−C1 bond length
(1.739(3) Å) is shorter than that in the L2(iPr) ligand
(1.793(2) Å), but the P1−N1 bond distance (1.623(2) Å) is
longer than that in the neutral ligand (1.562(2) Å), indicating
that the electrons tend to delocalize within the N−P−C(allyl)
fragment. Moreover, the atoms C1, C5, C4, and C3 define a
plane, whereas C2, a saturated sp3-hybridized carbon, deviates
from the plane by 0.168 Å, with the relatively stronger acid
proton H2 remaining unaffected. This is consistent with the
bond lengths: the C3−C4 bond (1.336(5) Å), for instance, is
an obvious double bond, much shorter than the single bonds of
C1−C2 (1.527(4) Å), C2−C3 (1.512(4) Å), and C4−C5
(1.484(4) Å), suggesting that the C1−C5 ring is not a
delocalized pentahapto structure. Thus, we deduced that, in
comparison with the cleavage of the conventional C−H bond
on the Cp ring, cleavage of the C−H bond on the allylic methyl
fragment not only was accidental but also was necessary,
depending on the nature of ligand, although the C−H bond
activation of this type was against the basic acid−base theory.
On the other hand, it is well known that the rare-earth metal
bis(alkyl) complexes can be prepared by three methods: (i) the
Figure 5. X-ray structure of 3b (40% probability of thermal ellipsoids).
Hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and
angles (deg): P1−C1 1.764(6), P1−N1 1.598(5), N1−Li1 1.969(11),
Li1−Cl1 2.300(12), Y1−Cl1 2.624(2), Y1−CpCent 2.405, Y1−C38
2.369(9), Y1−C42 2.373(6); C1−P1−N1 108.9(3), Y1−Cl1−Li1
107.7(3), C38−Y1−C42 99.8(3).
serving as a bridge, connects the yttrium atom and nitrogen
atom. Of particular note is that the P1−C1 bond length
(1.764(6) Å) in 3b is between 1.739(3) Å (3a) and 1.793(2) Å
(L2(iPr)), while the P1−N1 bond length (1.598(5) Å) is within
the range from 1.623(2) Å (3a) to 1.562(2) Å (L2(iPr)).
Switching the central metal to lutetium, the equimolar
reaction between Lu(CH2SiMe3)3(thf)2 and L2(iPr) in the
absence of LiCl still generated a mixture of two bis(alkyl)
i
products [C5HMe3(η3-CH2)−PPh2N−C6H3 Pr2]Lu-
i
(CH2SiMe3)2(thf) (4a) and (C5Me4−PPh2N−C6H3 Pr2)Lu-
1
(CH2SiMe3)2 (4b) in a 5:1 ratio (Scheme 5). The H NMR
spectrum shows that the structure of 4a is analogous to that of
3a, and so it is not discussed in detail. In particular, the Lu−
CH2SiMe3 methylene protons of 4a exhibit two doublets at δ =
−0.51 and −0.40 ppm, but those of 4b only present a broad
singlet at δ = −0.62 ppm. The structure of 4b was further
identified by X-ray crystallography to be a THF-free monomer
(Figure 6), which is different from these lutetium bis(alkyl)s
(2c, 5c, 7c, and 9b) that contain a solvent molecule (vide
infra). On the basis of these results, in the absence of LiCl, we
studied the reaction of Y(CH2SiMe3)3(thf)2 with L2(iPr),
which also leads to the formation of a mixture of two bis(alkyl)
products that are analogous to the 4a and 4b.
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Figure 7. X-ray structure of 5b (40% probability of thermal ellipsoids).
Hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and
angles (deg): P1−C1 1.755(3), P1−N1 1.603(2), Y1−Cpcent 2.538,
Y1−C1 2.670(3), Y1−C2 2.759(3), Y1−C9 2.790(3), Y1−C3
2.899(3), Y1−C4 2.935(3), Y1−N1 2.472(2), Y1−O1 2.388(2),
Figure 6. X-ray structure of 4b (40% probability of thermal ellipsoids).
Hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and
angles (deg): Lu1−Cpcent 2.362, Lu1−C34 2.327(8), Lu1−C38
2.338(8), P1−C1 1.774(7), P1−N1 1.627(5), Lu1−N1 2.297(5);
C1−P1−N1 102.1(3), Cpcent−Lu1−N1 94.2, C34−Lu1−C38
108.4(3).
Y1−C30 2.404(3), Y1−C34 2.405(3); C1−P1−N1 103.5(1), Cpcent
−
Y1−N1 88.54, C30−Y1−C34 109.8(1).
Preparation of the IndPN-type Bis(alkyl) Complexes
5a−5c, 6, and 7a−7c. The tremendous reactivity of CpPN-
type ligands L1(Me), L1(iPr), L2(Me), and L2(iPr) with rare-
earth metal tris(alkyl)s promoted us to investigate their indenyl
derivatives, IndPN-type ligands C9H7−PPh2N−C6H3R2 (R =
complexes.5b,21 However, it is noteworthy that the bond
distances Y1−C3 (2.899(3) Å) and Y1−C4 (2.935(3) Å) are
obviously longer, suggesting that the indenyl ligand, bonding to
the yttrium center, tends to adopt an η3-bonding fashion rather
than an η5-binding mode. The strong tendency of the η3-
coordination mode can also be reflected by the longer bond
distance Y1−Cpcent (2.538 Å), which is much longer than those
analogous distances in (η5-Ind-NHC)Y(CH2SiMe3)2 (2.396
Å),5b [{(η5-Ind)CMe2(η5-Ind)}Y{1,3-(SiMe3)2C3H3}] (2.331
and 2.341 Å),21a and [(η5-Ind′)2Y(μ-H)]2 (2.343−2.368 Å).21d
To the best of our knowledge, an η3-indenyl-based yttrium
complex, [(η3:η3-Ind-CMe2-Ind)2Y]−[Li(thf)4]+(thf), was also
reported by Carpentier, in which the bond distances between
two carbon atoms (away from the metal center) and the
yttrium center are 2.948(5) and 2.949(5) Å, respectively.21c As
for the scandium complex 6, the bond distances Sc1−C3
(2.668(5) Å) and Sc1−C4 (2.707(5) Å) are also beyond the
distances, 2.468(5)−2.627(4) Å, in η5-indenyl coordinated
scandium complexes, indicating the trend of η3-indenyl bonding
mode as well (Figures 8 and 9).5b,22
i
Me, L3(Me); R = Et, L3(Et); R = Pr, L3(iPr)). So far, Ind-
based ligands have shown versatile coordination modes (η1, η2,
η3, η4, η5, η6, η9) when attaching to transition metals,9a,20 which
further reinforced our interest in rare-earth metal complexes
featuring diverse Ind coordination modes, whose number and
variety remain limited to date. The straightforward protonolysis
reaction of these ligands L3(Me), L3(Et), and L3(iPr) with
Ln(CH2SiMe3)3(thf)2 (Ln = Sc, Y, and Lu) at room
temperature generated the IndPN-type bis(alkyl) complexes
5a−5c, 6, and 7a−7c, selectively (Scheme 6). The multinuclear
spectra (1H, 13C, and 31P) and X-ray diffraction clearly
confirmed their structures. All these complexes were analogous;
thus, only complexes 5b and 6 were discussed in detail. X-ray
diffraction analysis identified that the yttrium complex 5b was a
monomeric bis(alkyl)s coordinated by a THF molecule (Figure
7). The bond distances Y1−C1 (2.670(3) Å), Y1−C2
(2.759(3) Å), and Y1−C9 (2.790(3) Å) almost fall in the
2.617(8)−2.784(5) Å range for the η5-indenyl-based yttrium
Preparation of the FluPN-type Bis(alkyl) Complexes 8
and 9a, 9b. The IndPN-type bis(alkyl) complexes 5a−5c, 6,
and 7a−7c demonstrate the propensity of the phosphazene side
Scheme 6. Synthesis of the IndPN-type Complexes 5a−5c, 6, and 7a−7c
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10 h successfully took place and afforded the corresponding
rare-earth metal bis(alkyl) complexes 8 and 9a, 9b in good
1
yields, respectively (Scheme 7). The H NMR spectroscopic
Scheme 7. Synthesis of the FluPN-type Complexes 8 and 9a,
9b
analysis reveals that the scandium complexes 8 and 9a give two
doublets at δ = 0.29 and 0.59 ppm and δ = 0.30 and 0.60 ppm,
respectively, assigned to the methylene protons of the Sc−
CH2SiMe3 groups, but the lutetium complex 9b shows two
overlapped singlets at δ = −0.25 and −0.36 ppm. In addition,
the resonances from the coordinated THF molecules are also
detected. It is of interest to note that the Flu quaternary carbon
atoms C13 of 8 and 9a, 9b resonate at δ = 59.14, 59.17, and
60.65 ppm as a doublet (JPC = 108.0−114.0 Hz), respectively,
which are significantly lower than those resonances at δ =
79.0−93.49 ppm for η3- or η5-bonding fluorenyl rare-earth
metal complexes, suggesting an unusual structure for 8 and 9a,
9b.5a,6a,23 Complex 9b, as a representative example, was
subsequently identified by X-ray diffraction analysis. The
lutetium center adopts a distorted trigonal-bipyramidal
geometry in the solid state (Figure 10). Two alkyl groups
and the C13 atom occupy the equatorial positions, while the
oxygen and the nitrogen are located in the pseudoaxial
positions. The bond distance of Lu1−C13 (2.584(4) Å) is
Figure 8. X-ray structure of 6 (40% probability of thermal ellipsoids).
Hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and
angles (deg): P1−C1 1.748(5), P1−N1 1.606(4), Sc1−Cpcent 2.287,
Sc1−C1 2.457(5), Sc1−C2 2.529(5), Sc1−C9 2.564(5), Sc1−C3
2.668(5), Sc1−C4 2.707(5), Sc1−N1 2.195(4), Sc1−C32 2.204(5),
Sc1−C36 2.197(6); C1−P1−N1 100.9(2), Cpcent−Sc1−N1 96.8,
C32−Sc1−C36 104.2(2).
Figure 9. X-ray structure of 7a (40% probability of thermal ellipsoids).
Hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and
angles (deg): P1−C1 1.770(5), P1−N1 1.627(4), Sc1−Cpcent 2.283,
Sc1−C1 2.465(5), Sc1−C2 2.518(5), Sc1−C9 2.562(5), Sc1−C3
2.654(5), Sc1−C4 2.707(5), Sc1−N1 2.213(4), Sc1−C34 2.206(5),
Sc1−C38 2.220(4); C1−P1−N1 100.4(2), Cpcent−Sc1−N1 96.6,
C34−Sc1−C38 103.9(2).
arm to enforce the low η3-indenyl coordination even with the
rare-earth metals. This greatly encouraged us to explore the
possible low fluorenyl coordination. The FluPN-type ligands,
therefore, were prepared by the Staudinger reaction of C13H9−
PPh2 with 1.5 equiv of ArN3.9a We first synthesized one FluPN-
i
type ligand C13H9−PPh2N−C6H3 Pr2 featuring the 2,6-
diisopropylphenyl (Dipp) substituent at the nitrogen atom,
which unfortunately could not react with Ln(CH2SiMe3)3(thf)2
(Ln = Sc, Y, and Lu) even at 50 °C. Aiming at probing the
influence of the substituent at nitrogen, two less sterically
demanding FluPN-type ligands C13H9−PPh2N−C6H4R (R =
H, L4(H); R = Me, L4(Me)) were further used. The acid−base
reaction between Ln(CH2SiMe3)3(thf)2 (Ln = Sc and Lu) and
1 equiv of ligands L4(H) and L4(Me) at room temperature at
Figure 10. X-ray structure of 9b (40% probability of thermal
ellipsoids). Hydrogen atoms are omitted for clarity. Selected bond
lengths (Å) and angles (deg): P1−C13 1.752(4), P1−N1 1.612(3),
Lu1−C13 2.584(4), Lu1−N1 2.309(3), Lu1−C33 2.320(4), Lu1−
C37 2.338(4); C13−P1−N1 104.2(2), C33−Lu1−C37 109.4(1).
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a
Table 1. Ethylene Polymerization by All Catalyst Precursors 1−9 under Various Conditions
b
c
d
d
e
run
cat
AlR3
T (°C)
yield (g)
productivity
activity
Mw (103)
Mw/Mn
Tm (°C)
1
2
3
1
50
50
25
50
50
50
80
50
50
50
50
50
50
50
50
50
trace
0.27
0.38
1.13
0.65
0.42
0.72
0.34
2.83
trace
0.28
0.60
0.20
0.44
0.18
0.36
1
AliBu3
AliBu3
AliBu3
AliBu3
AliBu3
AliBu3
AliBu3
AliBu3
AlMe3
AlEt3
AliBu3
AliBu3
AliBu3
AliBu3
AliBu3
14
19
162
228
678
390
252
432
2040
568
10.6
14.4
12.5
5.0
5.34
2.11
2.03
1.69
2.31
1.38
1.75
2.24
126
130
136
126
115
124
127
130
2a
2a
2a
2a
2a
2a
2a
5a
5a
5a
6
f
4
57
5
33
g
6
21
1.6
7
36
3.3
h
8
34
4.2
i
9
142
42.4
10
11
12
13
14
15
16
14
30
10
22
9
168
360
120
264
108
216
9.1
6.7
5.72
1.97
2.34
2.65
1.58
2.07
128
132
133
132
123
125
4.2
7a
8
5.8
3.3
9
18
14.1
a
Polymerization conditions: Sc (20 μmol), [Sc]/AlR3/[Ph3C][B(C6F5)4] = 1/10/1 (mol/mol/mol), toluene (50 mL), Tp = 50 °C, ethylene 1 bar, 5
b
c
d
min, unless otherwise noted. Given in kg of PE (molSc bar)−1. Given in kg of PE (molSc h bar)−1. Determined by GPC in 1,2,4-trichlorobenzene
e
f
g
h
at 150 °C against polystyrene standard. Determined by DSC. AliBu3 (100 μmol, 5 equiv). AliBu3 (400 μmol, 20 equiv). Sc (10 μmol), AliBu3 (50
i
μmol, 5 equiv), 1 min. Sc (20 μmol), AliBu3 (100 μmol, 5 equiv), 15 min.
shorter than these analogous distances of the Lu−Cp(Flu)
(2.638(3)−2.724(3) Å),5a,6a but all of these large distances
between the remaining Flu carbon atoms (C1−C12) and the
central lutetium exceed 3.104 Å, suggesting that the Flu ligand
bonds to the metal center in a rare η1 mode. In addition, the
bond distance of Lu1−N1 (2.309(3) Å) is reasonably shorter
than that of Lu1−N1 (2.360(2) Å) in (η3-Flu−C5H4N)Lu-
(CH2SiMe3)2(thf),6a indicating that the presence of the
phosphazene side arm, which interacts with the metal center
by the nitrogen atom, enforces the low hapticity of the Flu
ligand. As far as we are aware, to date, there are various bonding
modes (η1, η2, η3, η5, η6) of the Flu moiety in the zirconocenes
and lanthanidocenes established by X-ray diffraction analysi-
s,5a,6a,23 but this type of η1-bonding mode of the Flu moiety in 8
and 9a, 9b remains extremely limited for rare-earth metal
complexes, which was only observed in [(FluSiMe2N-tBu)YH-
(thf)2]2.24
Ethylene Polymerization. All these complexes 1−9 have
been preliminarily tested as the precatalysts for ethylene
polymerization under various conditions (Table 1). It is found
that the polymerization activity strongly depends on the ionic
radius of the central metal. Upon activation with AlR3 and
[Ph3C][B(C6F5)4] together, only the smallest scandium
complexes show high activity for the ethylene polymerization;
those based on yttrium, lutetium, samarium, and neodymium
ions are all inert.12g,25 This can be attributed to the more Lewis
acidic nature of the Sc3+ ion and non-THF coordination. In
addition, the activity of these scandium complexes is influenced
by both the sterics and the electronics of the ligand; thus, the
activity follows the trend of 2a (iPr) > 1 (Me) (runs 2 and 5), 9
(Me) > 8 (H) (runs 15 and 16), and 5a (Me) > 7a (iPr) > 6
(Et) (runs 12−14), respectively. The highest activity (TOF)
can reach 2040 kg of PE (molSc h bar)−1 within 1 min (run 8),
and the productivity (TON) can also be up to 142 kg of PE
(molSc bar)−1 under a prolonging 15 min (run 9).
the AliBu3/2a ratio is 5:1, the polymerization shows the highest
acitivity (run 4); however, addition of a larger excess amount of
AliBu3 (10 and 20 equiv) obviously decreases the catalyst
activity, probably due to formation of a dormant state where
the active site is blocked by a bridging aluminum species (runs
5 and 6).26 In addition, the variation of catalytic activity caused
by trialkylaluminum, which is in a trend of AliBu3 > AlEt3 ≫
AlMe3 (5a is chosen as the precursor), may be attributed to the
interaction between the scandium catalyst and the aluminum
cocatalyst molecule (runs 10−12).27 Meanwhile, the Mw clearly
decreases with the increase of AliBu3 (runs 4−6), showing the
presence of a chain-transfer reaction between the scandium
cation and the aluminum center.12e,g On the basis of the above
results and the previous reports,12c−e,g,r,26 the roles of AlR3 in
the process of polymerization are: (1) stabilizing the formed
cationic active species, (2) a scavenger for removing impurities,
and (3) a chain-transfer agent.
The resulting polyethylenes (PEs) are measured by GPC,
which show that the weight-average molecular weight of these
PE samples is much lower (Mw = (1.6−42.4) × 103). It can be
attributed to the polymer chain transfer to the alkylaluminum
cocatalyst.28 The H NMR spectra of the resultant PEs do not
1
show any double bond signals, suggesting the absence of a β−H
elimination reaction (see the Supporting Information).28b
Meanwhile, the narrow and unimodal molecular weight
distribution is indicative of the single-site nature of the active
metal center, except for runs 2 and 11, which show a shoulder
peak with a wide distribution likely due to the formation of two
active species at high temperature. In the DSC curve, we also
find that all of these PE samples show a sharp endothermic
melting peak (Tm) in the range of 115−136 °C, which is lower
than those of high-molecular-weight PEs (up to 141 °C).28 In
addition, the Tm clearly becomes lower with an increase of
AliBu3 (runs 4−6). Study on the copolymerization of ethylene
and other monomers is in progress.
Noteworthy is that the presence of AlR3 is essential to
construct an active catalyst system (run 1), and its loadings and
types have remarkable influences on the activity of the catalyst
system and the molecular weight of polyethylene (PE). When
CONCLUSIONS
■
We have demonstrated the synthesis and full characterization of
a new family of CpPN-type, CpMePN-type, IndPN-type, and
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program.33 Refinement was performed on F2 anisotropically for all
non-hydrogen atoms by the full-matrix least-squares method. The
hydrogen atoms were placed at the calculated positions and were
included in the structure calculation without further refinement of the
parameters.
FluPN-type rare-earth metal bis(alkyl) complexes bearing
diverse η5, η3-allyl, η3, and η1 coordination modes. In particular,
we find that these reactions strongly depend on the substituents
at the nitrogen atom and Cp ring and the type of central metal.
Reaction of the CpPN-type ligands with Ln(CH2SiMe3)3(thf)2
or with LiCH2SiMe3 and LnCl3(thf)2 readily gives the CpPN-
type rare-earth metal bis(alkyl)s with the classical η5-bonding
mode; however, the CpMePN-type ligands react with Ln-
(CH2SiMe3)3(thf)2 to generate the rare-earth metal bis(alkyl)s
with an unusual η3-allylic coordination mode, limiting to both
the yttrium and the lutetium central metal. It is of interest to
note that the obtained IndPN-type bis(alkyl) complexes tend to
adopt an η3-bonding fashion rather than an η5-binding mode,
whereas the more bulky FluPN-type bis(alkyl) complexes
unexpectedly take a lower η1 coordination mode, indicating that
the strongly donating phosphazene side arm, which interacts
with the metal center by the nitrogen atom, facilitates to
enforce the low Ind and Flu hapticities. In addition, upon
activation with AlR3 and [Ph3C][B(C6F5)4] together, only the
scandium complexes show good to high catalytic activity for
ethylene polymerization and produce polyethylene with low
molecular weight. The catalytic activity clearly depends on the
sterics and electronics of the ligand, the loading and the type of
AlR3 cocatalyst, the polymerization temperature, and the
polymerization time.
By the way, crystals of 2d (Sm) and 2e (Nd) were measured on a
Stoe IPDS2 diffractometer at 100 or 180 K. Data were processed using
the XAREA program system.34 2d was solved by using the SIR-92
program,35 2e by using SHELXS-97.36 Refinements were performed
by using SHELXL-97.36
i
Synthesis of the Ligand C5H4PPh2−NH−C6H3 Pr2 (L1(iPr)).
To 4.48 g of NaC5H5 (50.9 mmol, 1.08 equiv) in 150 mL of pentane at
0 °C was added 10.42 mL of PPh2Cl (47.2 mmol, 1.00 equiv). The
mixture was stirred for 16 h at room temperature, and then 5 mL of
ethane-1,2-diol was added. The solution was decanted from the
precipitate, the precipitate was washed twice with 20 mL of pentane,
and the solvent of the transferred solution was evaporated in vacuum.
The residue was dissolved in 150 mL of THF, and 10.35 g of
C6H3(iPr2)N3 (50.9 mmol, 1.08 equiv) was added at 0 °C and stirred
for 16 h at 50 °C. All volatiles were removed under vacuum, and the
residue was crystallized out of 50 mL of hexane. The powder was
filtered, washed with 2 × 10 mL of hexane, and dried under vacuum in
63% yield (12.7 g) as a pale yellow powder.
Synthesis of the Ligand C5H4PPh2−NH−C6H3Me2 (L1(Me)).
Following a similar procedure described for the preparation of ligand
L1(iPr), the ligand L1(Me) was isolated from the Staudinger reaction
of C5H5−PPh2 (2.50 g, 10 mmol) with 1.5 equiv of C6H3(Me2)N3
1
(2.20 g, 15 mmol) as pale yellow powder in a 83% yield (3.07 g). H
NMR (600 MHz, C6D6, 7.16 ppm, 25 °C): δ 2.01 (s, 6H, Ar−CH3),
2
2
EXPERIMENTAL SECTION
4.40 (d, JPH = 6.0 Hz, 1H, NH), 6.71−6.72 (d, JHH = 6.0 Hz, 2H,
C5H4), 6.78−6.80 (quart, 2H, C5H4), 6.81−6.87 (m, 5H, Ph-H and
Ar-H), 6.90−6.92 (m, 2H, Ph-H), 6.97−7.00 (m, 2H, Ph-H), 7.34−
7.37 ppm (m, 4H, Ph-H). 31P NMR (162 MHz, C6D6, 25 °C): δ 25.12
ppm (s).
■
General Procedures and Materials. All reactions were carried
out under a dry and oxygen-free argon atmosphere by using Schlenk
techniques or under a nitrogen atmosphere in an MBraun glovebox.
All solvents were purified from the MBraun SPS system. Organo-
metallic samples for NMR spectroscopic measurements were prepared
in the glovebox by use of NMR tubes sealed with paraffin film. 1H and
13C NMR spectra were recorded on a Bruker AV600 (FT, 600 MHz
for 1H; 150 MHz for 13C) spectrometer. 31P NMR spectra were
recorded on a Bruker AV400 (FT, 162 MHz) spectrometer. NMR
Synthesis of the Ligand C5Me4H−PPh2N−C6H3Me2
(L2(Me)). Following a similar procedure described for the preparation
of ligand L1(iPr), the ligand L2(Me) was isolated from the Staudinger
reaction of C5Me4H−PPh2 (3.06 g, 10 mmol) with 1.5 equiv of
C6H3(Me2)N3 (2.20 g, 15 mmol) as a pale white powder in a 47%
1
1
1
assignments were confirmed by H−1H COSY and H−13C HMQC
experiments when necessary. Elemental analyses were performed at
the National Analytical Research Centre of Changchun Institute of
Applied Chemistry (CIAC). These ligands L1(Me), L1(iPr), L2(Me),
L2(iPr), L3(Me), L3(Et), L3(iPr), L4(H), and L4(Me) were prepared
yield (2.00 g). H NMR (600 MHz, C6D6, 7.16 ppm, 25 °C): δ 0.80
3
(d, JHH = 6.0 Hz, 3H, C5Me4H), 1.48 (s, 3H, C5Me4H), 1.60 (s, 3H,
C5Me4H), 1.67 (s, 3H, C5Me4H), 2.32 (s, 6H, Ar−CH3), 3.11−3.14
3
(quart, 1H, C5Me4H), 6.89−7.11 (m, 7H, Ar-H), 7.19 (d, JHH = 6.0
Hz, 2H, Ar-H), 7.68−7.72 (m, 2H, Ar-H), 7.92−7.96 ppm (m, 2H, Ar-
H). 13C NMR (150 MHz, C6D6, 128.06 ppm, 25 °C): δ 10.57 (s, 1C,
C5Me4), 11.08 (s, 1C, C5Me4), 12.17 (s, 1C, C5Me4), 15.02 (s, 1C,
C5Me4), 21.61 (s, 2C, Ar-CH3), 53.57 (d, 2JPC = 10.5 Hz, 1C, C5Me4),
118.76 (s, 2C, Ar-C), 127.43 (d, 3JPC = 10.5 Hz, 2C, Ar-C), 128.35 (s,
by following the known procedure.8,9 Ln(CH2SiMe3)3(thf)2 was
29
synthesized as described earlier. Organoborate [Ph3C][B(C6F5)4] was
synthesized following the literature procedures.30 Toluene was distilled
from sodium/benzophenone under nitrogen and degassed thoroughly
prior to use. Polymerization grade ethylene was dried by passing
through a column filled with activated molecular sieves (4 Å). The
molecular weights (Mn) and molecular weight distributions (Mw/Mn)
of polyethylene were measured by means of gel permeation
chromatography (GPC) on a PL-GPC 220-type high-temperature
chromatograph equipped with three PL-gel 10 μm Mixed-B LS type
columns at 150 °C. 1,2,4-Trichlorobenzene (TCB), containing 0.05
w/v % 2,6-di-tert-butyl-p-cresol (BHT), was employed as the solvent at
a flow rate of 1.0 mL min−1. The calibration was made by polystyrene
standard Easi Cal PS-1 (PL Ltd.). Tm of polyethylene was measured
through DSC analyses, which were carried out on a Q 100 DSC from
TA Instruments under a nitrogen atmosphere at heating and cooling
rates of 10 °C min−1 (temperature range: 25−300 °C).
X-ray Crystallographic Studies. Crystals for X-ray analysis were
obtained as described in the preparations. The crystals were
manipulated in a glovebox. Data collections were performed at
−88.5 °C on a Bruker SMART APEX diffractometer with a CCD area
detector, using graphite-monochromated Mo Kα radiation (λ =
0.71073 Å). The determination of crystal class and unit cell parameters
was carried out by the SMART program package.31 The raw frame
data were processed using SAINT and SADABS to yield the reflection
data file.32 The structures were solved by using the SHELXTL
3
2C, Ar-C), 130.64 (s, 1C, Ar-C), 130.96 (d, JPC = 4.5 Hz, 2C, Ar-C),
131.80 (d, 3JPC = 7.5 Hz, 2C, Ar-C), 131.99 (d, 2JPC = 9.0 Hz, 2C, Ar-
C), 132.79 (d, 3JPC = 10.5 Hz, 2C, Ar-C), 135.21 (s, 1C, Ar-C), 135.42
2
(d, JPC = 13.5 Hz, 1C, C5Me4), 135.94 (s, 1C, Ar-C), 136.79 (s, 1C,
3
Ar-C), 137.46 (s, 1C, Ar-C), 140.91 (d, JPC = 7.5 Hz, 1C, C5Me4),
3
148.74 (d, JPC = 6.0 Hz, 1C, C5Me4), 149.03 (s, 1C, C5Me4), 157.27
2
ppm (d, JPC = 10.5 Hz, 1C, Ar-C). Anal. Calcd for C29H32NP: C,
81.85; H, 7.58; N, 3.29. Found: C, 82.22; H, 7.45; N, 3.20.
i
Synthesis of the Ligand C5Me4H−PPh2N−C6H3 Pr2 (L2(iPr)).
Following a similar procedure described for the preparation of ligand
L1(iPr), the ligand L2(iPr) was isolated from the Staudinger reaction of
C5Me4H−PPh2 (3.06 g, 10 mmol) with 1.5 equiv of C6H3(iPr )N3
2
(3.05 g, 15 mmol) as a white powder in a 58% yield (2.78 g). 1H NMR
3
(600 MHz, C6D6, 7.16 ppm, 25 °C): δ 0.78 (d, JHH = 12.0 Hz, 3H,
C5Me4H), 1.11 (d, 3JHH = 6.0 Hz, 6H, Ar−CH(CH3)2), 1.21 (d, 3JHH
=
12.0 Hz, 6H, Ar−CH(CH3)2), 1.52 (s, 3H, C5Me4H), 1.61 (s, 3H,
C5Me4H), 1.70 (s, 3H, C5Me4H), 3.10−3.13 (quart, 1H, C5Me4H),
3.64−3.71 (sept, 2H, Ar−CH(CH3)2), 7.01−7.09 (m, 4H, Ar-H),
3
7.13−7.15 (m, 3H, Ar-H), 7.23 (d, JHH = 6.0 Hz, 2H, Ar-H), 7.59−
7.63 (m, 2H, Ar-H), 7.93−7.96 ppm (m, 2H, Ar-H). 13C NMR (150
MHz, C6D6, 128.06 ppm, 25 °C): δ 10.56 (s, 1C, C5Me4), 12.17 (s,
1C, C5Me4), 14.73 (s, 1C, C5Me4), 15.08 (s, 1C, C5Me4), 23.89 (s, 2C,
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Organometallics
Article
Ar−CH(CH3)2), 24.43 (s, 2C, Ar−CH(CH3)2), 28.93 (s, 2C, Ar-
CH(CH3)2), 53.68 (d, 2JPC = 21.0 Hz, 1C, C5Me4), 119.68 (s, 1C, Ar-
C), 123.15 (s, 2C, Ar-C), 128.39 (d, 3JPC = 10.5 Hz, 2C, Ar-C), 128.50
(s, 1C, Ar-C), 130.58 (s, 1C, Ar-C), 131.03 (s, 1C, Ar-C), 131.84 (d,
2JPC = 10.5 Hz, 2C, Ar-C), 132.19 (s, 1C, Ar-C), 132.87 (d, 3JPC = 10.5
Hz, 2C, Ar-C), 134.35 (s, 1C, Ar-C), 135.10 (s, 1C, Ar-C), 135.37 (d,
2JPC = 15.0 Hz, 1C, C5Me4), 136.36 (s, 1C, Ar-C), 137.00 (s, 1C, Ar-
base reaction of Y(CH2SiMe3)3(thf)2 (0.495 g, 1.0 mmol) with 1 equiv
1
of ligand L1(iPr) (0.425 g, 1.0 mmol) in a 66% yield (0.501 g). H
NMR (600 MHz, C6D6, 7.16 ppm, 25 °C): δ −0.45 (br s, 4H,
CH2SiMe3), 0.45 (s, 18H, CH2SiMe3), 0.76 (br s, 12H, Ar−
CH(CH3)2), 1.18−1.24 (m, 4H, thf), 3.18−3.24 (sept, 2H, Ar−
CH(CH3)2), 3.70−3.72 (m, 4H, thf), 6.74−6.76 (quart, 2H, C5H4),
6.92−6.95 (m, 6H, Ph-H), 6.98−7.01 (m, 3H, C5H4 and Ar-H), 7.07−
7.08 (m, 2H, Ar-H), 7.46−7.49 ppm (m, 4H, Ph-H). 13C NMR (150
MHz, C6D6, 128.06 ppm, 25 °C): δ 4.67 (s, 6C, CH2SiMe3), 24.58 (br
s, 4C, Ar−CH(CH3)2), 25.03 (s, 2C, thf), 29.07 (s, 2C, Ar-
CH(CH3)2), 32.09 (d, JYC = 39.0 Hz, 2C, CH2SiMe3), 70.07 (s, 2C,
3
C), 143.09 (d, JPC = 6.0 Hz, 1C, C5Me4), 145.72 (s, 1C, C5Me4),
148.75 (d, 3JPC = 6.0 Hz, 1C, C5Me4), 157.38 ppm (d, 2JPC = 10.5 Hz,
1C, Ar-C). 31P NMR (162 MHz, C6D6, 25 °C): δ −15.07 ppm (s).
Anal. Calcd for C33H40NP: C, 82.29; H, 8.37; N, 2.91. Found: C,
82.62; H, 8.24; N, 2.82.
2
thf), 94.45 (d, JPC = 124.5 Hz, 1C, ipso-C5H4), 115.77 (d, JPC = 13.5
Hz, 2C, C5H4), 119.01 (d, 3JPC = 15.0 Hz, 2C, C5H4), 124.29 (d, 4JPC
=
Synthesis of the Ligand C13H9−PPh2N−C6H4Me (L4(Me)).
Following a similar procedure described for the preparation of ligand
L4(H) (ref), the ligand L4(Me) was prepared from the Staudinger
reaction of C13H9−PPh2 (3.50 g, 10 mmol) with 1.5 equiv of
C6H4MeN3 (1.99 g, 15 mmol) as a white powder in a 87% yield (3.93
g). 1H NMR (600 MHz, C6D6, 7.16 ppm, 25 °C): δ 2.20 (s, 3H, Ar−
CH3), 5.16 (d, 2JPH = 6.0 Hz, Flu-H), 6.80−6.83 (m, 4H, Ar-H), 6.90
4.5 Hz, 2C, Ar-C), 124.50 (d, 5JPC = 3.0 Hz, 1C, Ar-C), 128.35 (s, 4C,
Ph-C), 128.58 (d, JPC = 12.0 Hz, 2C, ipso-Ph-C), 132.37 (br s, 2C, Ph-
C), 133.19 (d, 2JPC = 9.0 Hz, 4C, Ph-C), 143.03 (d, 2JPC = 9.0 Hz, 1C,
3
ipso-Ar-C), 145.28 ppm (d, JPC = 6.0 Hz, 2C, Ar-C). 31P NMR (162
MHz, C6D6, 25 °C): δ 10.07 ppm (s). Anal. Calcd for
C41H61NPOYSi2: C, 64.80; H, 8.09; N, 1.84. Found: C, 65.18; H,
8.14; N, 1.76.
(t, 3JHH = 12.0 Hz, 2H, Ar-H), 6.99−7.10 (m, 8H, Ar-H), 7.34 (d, 3JHH
i
3
Synthesis of the Complex (C5H4−PPh2N−C6H3 Pr2)Lu-
= 6.0 Hz, 2H, Ar-H), 7.41−7.44 (m, 4H, Ar-H), 7.73 ppm (t, JHH
=
(CH2SiMe3)2(thf) (2c). Following a similar procedure described for
the preparation of complex 1, complex 2c was isolated from the acid−
base reaction of Lu(CH2SiMe3)3(thf)2 (0.580 g, 1.0 mmol) with 1
equiv of ligand L1(iPr) (0.425 g, 1.0 mmol) in a 62% yield (0.527 g).
1H NMR (600 MHz, C6D6, 7.16 ppm, 25 °C): δ −0.50 (br s, 4H,
CH2SiMe3), 0.39 (s, 18H, CH2SiMe3), 0.78 (br s, 12H, Ar−
CH(CH3)2), 1.38 (s, 4H, thf), 3.33−3.39 (sept, 2H, Ar−
CH(CH3)2), 3.60 (s, 4H, thf), 6.75−6.76 (quart, 2H, C5H4), 6.89−
6.93 (m, 6H, Ph-H), 6.96−7.04 (m, 5H, C5H4 and Ar-H), 7.42−7.46
ppm (m, 4H, Ph-H). 13C NMR (150 MHz, C6D6, 128.06 ppm, 25
°C): δ 4.49 (s, 6C, CH2SiMe3), 24.81 (br s, 4C, Ar−CH(CH3)2),
25.65 (s, 2C, thf), 28.92 (s, 2C, Ar-CH(CH3)2), 40.21 (s, 2C,
CH2SiMe3), 68.34 (s, 2C, thf), 92.47 (d, JPC = 121.5 Hz, 1C, ipso-
12.0 Hz, 2H, Ar-H).
Synthesis of the Complex (C5H4−PPh2N−C6H3Me2)Sc-
(CH2SiMe3)2 (1). Under a nitrogen atmosphere, to a mixture of
THF and a toluene solution (10 mL) of Sc(CH2SiMe3)3(thf)2 (0.451
g, 1.0 mmol) was added 1 equiv of ligand L1(Me) (0.369 g, 1.0 mmol)
slowly at room temperature. The mixture was stirred for 7 h to afford a
pale yellow solution. Evaporation of the solvent left complex 1 as pale
yellow crystalline solids (0.332 g, 56%). Recrystallization from a
mixture of toluene and hexane gave pale yellow single crystals suitable
1
for X-ray analysis. H NMR (600 MHz, C6D6, 7.16 ppm, 25 °C): δ
0.09 (d, 2JHH = 6.0 Hz, 4H, CH2SiMe3), 0.31 (s, 18H, CH2SiMe3), 2.03
(s, 6H, Ar−CH3), 6.68−6.69 (quart, 2H, C5H4), 6.85−6.89 (m, 7H,
C5H4 and Ph-H and Ar-H), 6.96−6.99 (m, 4H, Ph-H), 7.40−7.43 ppm
(m, 4H, Ph-H). 13C NMR (150 MHz, C6D6, 128.06 ppm, 25 °C): δ
3.91 (s, 6C, CH2SiMe3), 21.58 (br s, 2C, Ar-CH3), 41.76 (br s, 2C,
2
3
C5H4), 117.76 (d, JPC = 13.5 Hz, 2C, C5H4), 117.96 (d, JPC = 13.5
Hz, 2C, C5H4), 124.67 (d, 4JPC = 3.0 Hz, 2C, Ar-C), 125.14 (d, 5JPC
=
2
3.0 Hz, 1C, Ar-C), 128.35 (s, 4C, Ph-C), 128.70 (d, JPC = 12.0 Hz, 2C,
CH2SiMe3), 92.03 (d, JPC = 120.0 Hz, 1C, ipso-C5H4), 117.95 (d, JPC
ipso-Ph-C), 132.76 (br s, 2C, Ph-C), 133.38 (d, 2JPC = 10.5 Hz, 4C, Ph-
3
= 12.0 Hz, 2C, C5H4), 118.84 (d, JPC = 15.0 Hz, 2C, C5H4), 124.61
2
3
4
C), 140.07 (d, JPC = 12.0 Hz, 1C, ipso-Ar-C), 145.74 ppm (d, JPC
=
(d, JPC = 4.5 Hz, 2C, Ar-C), 128.35 (s, 4C, Ph-C), 128.70 (d, JPC
=
6.0 Hz, 2C, Ar-C). 31P NMR (162 MHz, C6D6, 25 °C): δ 10.39 ppm
(s). Anal. Calcd for C41H61NPOLuSi2: C, 58.21; H, 7.27; N, 1.66.
Found: C, 58.45; H, 7.21; N, 1.64.
4
12.0 Hz, 2C, ipso-Ph-C), 128.96 (s, 1C, Ar-C), 129.50 (d, JPC = 3.0
Hz, 2C, Ph-C), 132.76 (d, 2JPC = 10.5 Hz, 4C, Ph-C), 135.23 (d, 3JPC
=
6.0 Hz, 2C, Ar-C), 142.94 ppm (d, JPC = 9.0 Hz, 1C, ipso-Ar-C). 31P
NMR (162 MHz, C6D6, 25 °C): δ 7.82 ppm (s). Anal. Calcd for
C33H45NPScSi2: C, 67.43; H, 7.72; N, 2.38. Found: C, 67.87; H, 7.78;
N, 2.29.
2
i
Synthesis of the Complex (C5H4−PPh2N−C6H3 Pr2)Sm-
(CH2SiMe3)2(thf) (2d). To a suspension of SmCl3(thf)2 (0.400 g,
1.0 mmol) and L1(iPr) (0.425 g, 1.0 mmol) in ether was added
dropwise at 0 °C a solution of LiCH2SiMe3 (3.04 mmol) in hexane.
The reaction mixture was stirred at 0 °C for another 1 h and
concentrated in vacuo to half of the original volume. Formed LiCl was
filtered off over Celite. The solvent was stripped off, and the residue
was extracted with hexane. Crystallization occurred by storage at −30
°C. Filtration and drying in a vacuum resulted in isolation of yellow
i
Synthesis of the Complex (C5H4−PPh2N−C6H3 Pr2)Sc-
(CH2SiMe3)2 (2a). Following a similar procedure described for the
preparation of complex 1, complex 2a was isolated from the acid−base
reaction of Sc(CH2SiMe3)3(thf)2 (0.451 g, 1.0 mmol) with 1 equiv of
ligand L1(iPr) (0.425 g, 1.0 mmol) in a 71% yield (0.459 g). 1H NMR
(600 MHz, C6D6, 7.16 ppm, 25 °C): δ 0.20 (br s, 4H, CH2SiMe3),
0.37 (br s, 24H, CH2SiMe3 and Ar−CH(CH3)2), 1.23 (br s, 6H, Ar−
CH(CH3)2), 3.40−3.46 (sept, 2H, Ar−CH(CH3)2), 6.78−6.79 (quart,
2H, C5H4), 6.87−6.91 (m, 4H, Ph-H), 6.96−7.03 (m, 6H, C5H4 and
Ph-H and Ar-H), 7.05−7.08 (m, 1H, Ar-H), 7.40−7.43 ppm (m, 4H,
Ph-H). 13C NMR (150 MHz, C6D6, 128.06 ppm, 25 °C): δ 3.91 (s,
6C, CH2SiMe3), 23.77 (br s, 2C, Ar−CH(CH3)2), 26.35 (br s, 2C, Ar−
CH(CH3)2), 28.80 (s, 2C, Ar-CH(CH3)2), 42.01 (s, 2C, CH2SiMe3),
1
microcrystalline solids in a 29% yield (0.220 g). H NMR (300 MHz,
C6D6, 7.16 ppm, 25 °C): δ 0.27 (br s, 12H, Ar−CH(CH3)2), 0.27 (br
s, 6H, Sm−CH2 or thf), 0.61 (s, 18H, CH2SiMe3), 1.89 (br s, 2H,
C5H4), 2.16 (br s, 6H, Sm−CH2 or thf), 2.95 (sept, 2H, Ar−
CH(CH3)2), 5.85 (d, 3JHH = 7.6 Hz, 2H, m-DippH), 6.07 (t, 3JHH = 7.5
Hz, 1H, p-DippH), 7.33−7.38 (m, 2H, Ph-H), 7.44−7.49 (m, 4H, Ph-
H), 9.18−9.24 (m, 4H, Ph-H), 9.80 ppm (br s, 2H, C5H4). 31P NMR
(121.5 MHz, C6D6, 25 °C): δ 18.1 ppm (br s). Anal. Calcd for
C41H61NPOSmSi2: C, 59.95; H, 7.49; N, 1.71. Found: C, 59.24; H,
7.24; N, 1.85.
2
92.75 (d, JPC = 120.0 Hz, 1C, ipso-C5H4), 118.38 (d, JPC = 12.0 Hz,
2C, C5H4), 119.19 (d, 3JPC = 15.0 Hz, 2C, C5H4), 124.87 (d, 4JPC = 3.0
5
Hz, 2C, Ar-C), 125.33 (d, JPC = 4.5 Hz, 1C, Ar-C), 127.71 (d, JPC
=
i
12.0 Hz, 2C, ipso-Ph-C), 128.75 (d, 3JPC = 12.0 Hz, 4C, Ph-C), 132.83
Synthesis of the Complex (C5H4−PPh2N−C6H3 Pr2)Nd-
4
2
(CH2SiMe3)2(thf) (2e). To a suspension of NdCl3(thf)2 (0.360 g,
1.0 mmol) and L1(iPr) (0.425 g, 1.0 mmol) in ether was added
dropwise at 0 °C a solution of LiCH2SiMe3 (3.04 mmol) in hexane.
The reaction mixture was stirred at 0 °C for another 1 h and
concentrated in vacuo to half of the original volume. Formed LiCl was
filtered off over Celite. The solvent was stripped off, and the residue
was extracted with hexane. Crystallization occurred by storage at −30
°C. Filtration and drying in a vacuum resulted in isolation of blue
(d, JPC = 1.5 Hz, 2C, Ph-C), 133.57 (d, JPC = 9.0 Hz, 4C, Ph-C),
139.82 (d, 2JPC = 9.0 Hz, 1C, ipso-Ar-C), 145.86 ppm (d, 3JPC = 6.0 Hz,
2C, Ar-C). 31P NMR (162 MHz, C6D6, 25 °C): δ 11.11 ppm (s). Anal.
Calcd for C37H53NPScSi2: C, 69.01; H, 8.30; N, 2.18. Found: C, 69.28;
H, 8.19; N, 2.21.
i
Synthesis of the Complex (C5H4−PPh2N−C6H3 Pr2)Y-
(CH2SiMe3)2(thf) (2b). Following a similar procedure described for
the preparation of complex 1, complex 2b was isolated from the acid−
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Organometallics
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1
microcrystalline solids in a 34% yield (0.231 g). H NMR (500 MHz,
C6D6, 7.16 ppm, 25 °C): δ −20.91 (br s, 2H, C5H4), −6.74 (br s, 2H,
C5H4), −4.26 (br s, 4H, Nd−CH2 or thf), −1.79 (br s, 6H, Ar−
CH(CH3)2), −1.61 (br s, 4H, Nd−CH2 or thf), 1.36 (br s, 6H, Ar−
CH(CH3)2), 2.45 (s, 18H, CH2SiMe3), 3.68 (br s, 1H, p-DippH), 4.46
recrystallized at −30 °C within 2 days to afford the mixture of
complexes 4a and 4b (4a: 0.129 g; 4b: 0.083 g).
1
Complex 4a: H NMR (600 MHz, C6D6, 7.16 ppm, 25 °C): δ
2
2
−0.51 (d, JHH = 12.0 Hz, 2H, LuCH2SiMe3), −0.40 (d, JHH = 12.0
3
Hz, 2H, LuCH2SiMe3), 0.35 (s, 18H, LuCH2SiMe3), 0.39 (d, JHH
=
3
3
2
6.0 Hz, 3H, Ar−CH(CH3)2), 0.40 (d, JHH = 6.0 Hz, 3H, Ar−
(d, JHH = 6.9 Hz, 2H, m-DippH), 8.33 (t, JHH = 7.5 Hz, 2H, Ph-H),
CH(CH3)2), 0.49 (d, 3JHH = 12.0 Hz, 3H, C5Me3HCH2), 1.30 (d, 3JHH
8.92 (d, JHH = 5.5 Hz, 4H, Ph-H), 14.83 ppm (br s, 4H, Ph-H). 31P
2
3
= 12.0 Hz, 3H, Ar−CH(CH3)2), 1.37 (m, 4H, thf), 1.40 (d, JHH
=
NMR (202.5 MHz, C6D6, 25 °C): δ −62.8 ppm (br s). Anal. Calcd for
C41H61NPONdSi2: C, 60.40; H, 7.54; N, 1.72. Found: C, 59.77; H,
7.34; N, 1.89.
12.0 Hz, 3H, Ar−CH(CH3)2), 1.64 (s, 3H, C5Me3HCH2), 1.77 (s, 3H,
C5Me3HCH2), 3.00−3.12 (sept, 1H, Ar−CH(CH3)2), 3.14−3.19
(quart, 1H, C5Me3HCH2), 3.76 (m, 4H, thf), 3.90−4.00 (sept, 1H,
Ar−CH(CH3)2), 4.23 (s, 1H, C5Me3HCH2−Lu), 4.35 (s, 1H,
C5Me3HCH2−Lu), 6.93−7.10 (m, 11H, Ar-H), 7.24 (br s, 1H, Ar-
H), 7.97 ppm (very br s, 1H, Ar-H). 13C NMR (150 MHz, C6D6,
128.06 ppm, 25 °C): δ 4.89 (s, 6C, CH2SiMe3), 11.12 (s, 1C,
C5Me3HCH2), 12.96 (s, 1C, C5Me3HCH2), 19.86 (s, 1C,
C5Me3HCH2), 21.75 (s, 1C, Ar−CH(CH3)2), 24.04 (s, 1C, Ar−
CH(CH3)2), 25.42 (s, 2C, thf), 26.34 (s, 1C, Ar−CH(CH3)2), 27.81
(s, 1C, Ar−CH(CH3)2), 28.61 (s, 1C, Ar-CH(CH3)2), 29.96 (s, 1C,
Ar-CH(CH3)2), 40.64 (s, 2C, LuCH2SiMe3), 52.46 (d, 2JPC = 21.0 Hz,
1C, C5Me3HCH2), 70.21 (s, 2C, thf), 70.98 (s, 1C, C5Me3HCH2−Lu),
124.06 (s, 2C, Ar-C), 124.56 (s, 2C, Ar-C), 124.86 (s, 2C, Ar-C),
128.98 (s, 1C, Ar-C), 131.38 (s, 2C, Ar-C), 131.73 (s, 2C, Ar-C),
132.88 (d, 3JPC = 9.0 Hz, 1C, Ar-C), 133.18 (d, 2JPC = 13.5 Hz, 2C, Ar-
C), 133.81 (s, 1C, Ar-C), 135.12 (d, 3JPC = 13.5 Hz, 2C, Ar-C), 141.57
Synthesis of the Complexes [C5HMe3(η3-CH2)−PPh2N−
i
C6H3 Pr2]Y(CH2SiMe3)2(thf) (3a) and (C5Me4−PPh2N−
i
C6H3 Pr2)Y(CH2SiMe3)2(LiCl)(thf) (3b). Under a nitrogen atmos-
phere, to a mixture of THF and a toluene solution (10 mL) of
Y(CH2SiMe3)3(thf)2 (0.495 g, 1.0 mmol) and LiCl (0.043 g, 1.0
mmol) was added 1 equiv of ligand L2(iPr) (0.482 g, 1.0 mmol) slowly
at room temperature. The mixture was stirred for 7 h to afford a yellow
solution. Evaporation of the solvent left a mixture of complexes 3a and
3b as yellow crystalline solids. Recrystallization from a mixture of
toluene and hexane at −30 °C within 12 h first gave pure complex 3a
as yellow crystalline solids in high yield (0.324 g); then the remaining
mother liquor was further recrystallized at −30 °C within 2 days to
afford the mixture of complexes 3a and 3b (3a: 0.133 g; 3b: 0.069 g).
1
Complex 3a: H NMR (600 MHz, C6D6, 7.16 ppm, 25 °C): δ
2
3
−0.30, −0.50 (AB, JHH = 12.0 Hz, 4H, YCH2SiMe3), 0.33 (d, JHH
=
2
3
6.0 Hz, 3H, Ar−CH(CH3)2), 0.36 (s, 18H, YCH2SiMe3), 0.45 (d, 3JHH
(d, JPC = 13.5 Hz, 1C, C5Me3HCH2), 145.45 (d, JPC = 7.5 Hz, 1C,
C5Me3HCH2), 146.13 (d, 3JPC = 9.0 Hz, 1C, C5Me3HCH2), 152.50 (d,
JPC = 16.5 Hz, 1C, C5Me3HCH2), 165.43 ppm (d, 2JPC = 18.0 Hz, 1C,
Ar-C). 31P NMR (162 MHz, C6D6, 25 °C): δ 14.95 ppm (s). Anal.
Calcd for C45H69ONPSi2Lu: C, 59.91; H, 7.71; N, 1.55. Found: C,
60.33; H, 7.61; N, 1.47.
3
= 6.0 Hz, 3H, Ar−CH(CH3)2), 0.53 (d, JHH = 12.0 Hz, 3H,
C5Me3HCH2), 1.19 (d, 3JHH = 12.0 Hz, 3H, Ar−CH(CH3)2), 1.30 (d,
3JHH = 6.0 Hz, 3H, Ar−CH(CH3)2), 1.33 (m, 4H, thf), 1.68 (s, 3H,
C5Me3HCH2), 1.88 (s, 3H, C5Me3HCH2), 2.93−2.99 (sept, 1H, Ar−
CH(CH3)2), 3.27−3.30 (quart, 1H, C5Me3HCH2), 3.76 (m, 4H, thf),
3.79−3.85 (sept, 1H, Ar−CH(CH3)2), 4.28 (s, 1H, C5Me3HCH2−Y),
4.51 (s, 1H, C5Me3HCH2−Y), 6.94−7.16 (m, 11H, Ar-H), 7.36 (br s,
1H, Ar-H), 7.95 ppm (very br s, 1H, Ar-H). 13C NMR (150 MHz,
C6D6, 128.06 ppm, 25 °C): δ 4.77 (s, 6C, CH2SiMe3), 11.04 (s, 1C,
C5Me3HCH2), 13.25 (s, 1C, C5Me3HCH2), 20.40 (s, 1C,
C5Me3HCH2), 21.65 (s, 1C, Ar−CH(CH3)2), 24.40 (s, 1C, Ar−
CH(CH3)2), 25.29 (s, 2C, thf), 25.43 (s, 1C, Ar−CH(CH3)2), 28.10
(s, 1C, Ar−CH(CH3)2), 28.60 (s, 1C, Ar-CH(CH3)2), 29.70 (s, 1C,
Ar-CH(CH3)2), 34.16 (d, JYC = 39.0 Hz, 2C, YCH2SiMe3), 52.98 (d,
2JPC = 15.0 Hz, 1C, C5Me3HCH2), 70.52 (s, 2C, thf), 73.25 (s, 1C,
C5Me3HCH2−Y), 124.04 (d, JPC = 27.0 Hz, 2C, Ar-C), 124.90 (s, 2C,
Ar-C), 128.35 (s, 2C, Ar-C), 128.82 (s, 1C, Ar-C), 131.21 (s, 2C, Ar-
C), 131.63 (s, 2C, Ar-C), 132.64 (d, 3JPC = 15.0 Hz, 1C, Ar-C), 133.01
(d, 2JPC = 7.5 Hz, 2C, Ar-C), 133.62 (s, 1C, Ar-C), 134.21 (s, 1C, Ar-
1
Complex 4b: H NMR (600 MHz, C6D6, 7.16 ppm, 25 °C): δ
−0.62 (br s, 4H, LuCH2SiMe3), 0.36 (s, 18H, LuCH2SiMe3), 1.19 (d,
3JHH = 6.0 Hz, 12H, Ar−CH(CH3)2), 2.02 (s, 6H, C5Me4), 2.20 (s, 6H,
C5Me4), 3.78−3.85 (sept, 2H, Ar−CH(CH3)2), 6.83−7.14 (m, 9H, Ar-
H), 7.34−7.38 (m, 2H, Ar-H), 7.63−7.66 ppm (m, 2H, Ar-H).
Synthesis of the Complex (Ind−PPh2N−C6H3Me2)Sc-
(CH2SiMe3)2 (5a). Following a similar procedure described for the
preparation of complex 1, complex 5a was isolated from the acid−base
reaction of Sc(CH2SiMe3)3(thf)2 (0.451 g, 1.0 mmol) with 1 equiv of
ligand L3(Me) (0.419 g, 1.0 mmol) in a 49% yield (0.294 g). 1H NMR
(600 MHz, C6D6, 7.16 ppm, 25 °C): δ −0.33 (br s, 2H, ScCH2SiMe3),
−0.19 (br s, 2H, ScCH2SiMe3), 0.24 (s, 18H, CH2SiMe3), 2.26 (s, 6H,
Ar−CH3), 6.88−7.02 (m, 11H, Ar-H), 7.18 (t, 3JHH = 6.0 Hz, 1H, Ar-
H), 7.24 (t, 3JHH = 12.0 Hz, 1H, Ar-H), 7.50−7.53 (m, 5H, Ar-H), 7.79
3
ppm (d, JHH = 12.0 Hz, 1H, Ar-H). 13C NMR (150 MHz, C6D6,
2
C), 135.01 (br s, 1C, Ar-C), 142.34 (d, JPC = 9.0 Hz, 1C,
C5Me3HCH2), 145.22 (d, JPC = 6.0 Hz, 1C, C5Me3HCH2), 145.90
128.06 ppm, 25 °C): δ 3.82 (s, 6C, CH2SiMe3), 22.26 (s, 2C, Ar-CH3),
45.32 (br s, 2C, ScCH2SiMe3), 74.93 (d, JPC = 121.5 Hz, 1C, Ind-C),
111.18 (d, 2JPC = 9.0 Hz, 1C, Ind-C), 121.58 (s, 1C, Ar-C), 122.62 (s,
1C, Ar-C), 123.45 (s, 1C, Ar-C), 123.66 (s, 1C, Ar-C), 124.04 (s, 1C,
3
3
(d, JPC = 4.5 Hz, 1C, C5Me3HCH2), 153.03 (d, JPC = 12.0 Hz, 1C,
C5Me3HCH2), 163.65 ppm (d, JPC = 12.0 Hz, 1C, Ar-C). 31P NMR
2
3
(162 MHz, C6D6, 25 °C): δ 14.04 ppm (s). Anal. Calcd for
C45H69ONPSi2Y: C, 66.23; H, 8.52; N, 1.72. Found: C, 66.63; H, 8.61;
N, 1.63.
Ar-C), 124.75 (s, 2C, Ar-C), 125.90 (d, JPC = 13.5 Hz, 1C, Ind-C),
128.35 (s, 2C, Ar-C), 128.73 (d, 3JPC = 12.0 Hz, 2C, Ar-C), 129.00 (d,
2JPC = 12.0 Hz, 2C, Ar-C), 129.82 (s, 2C, Ar-C), 131.30 (s, 1C, Ar-C),
132.50 (d, 2JPC = 10.5 Hz, 2C, Ar-C), 132.80 (s, 1C, Ar-C), 133.45 (d,
1
Complex 3b: H NMR (600 MHz, C6D6, 7.16 ppm, 25 °C): δ
3
3JPC = 10.5 Hz, 2C, Ar-C), 135.50 (d, JPC = 10.5 Hz, 1C, Ar-C),
−0.40 (br s, 4H, YCH2SiMe3), 0.36 (s, 18H, YCH2SiMe3), 1.00 (d,
3JHH = 6.0 Hz, 12H, Ar−CH(CH3)2), 1.24 (m, 4H, thf), 2.22 (s, 6H,
C5Me4), 2.24 (br s, 6H, C5Me4), 3.45 (m, 4H, thf), 3.79−3.85 (sept,
2H, Ar−CH(CH3)2), 6.82−7.13 (m, 11H, Ar-H), 7.34−7.38 ppm (m,
2H, Ar-H).
2
135.78 (s, 1C, Ar-C), 142.77 ppm (d, JPC = 9.0 Hz, 1C, Ar-C). 31P
NMR (162 MHz, C6D6, 25 °C): δ 6.35 ppm (s). Anal. Calcd for
C37H47NPSi2Sc: C, 69.67; H, 7.43; N, 2.20. Found: C, 70.13; H, 7.34;
N, 2.14.
Synthesis of the Complexes [C5HMe3(η3-CH2)−PPh2N−
Synthesis of the Complex (Ind−PPh2N−C6H3Me2)Y-
(CH2SiMe3)2(thf) (5b). Following a similar procedure described for
the preparation of complex 1, complex 5b was isolated from the acid−
base reaction of Y(CH2SiMe3)3(thf)2 (0.495 g, 1.0 mmol) with 1 equiv
i
C6H3 Pr2]Lu(CH2SiMe3)2(thf) (4a) and (C5Me4−PPh2N−
i
C6H3 Pr2)Lu(CH2SiMe3)2 (4b). Under a nitrogen atmosphere, to a
mixture of THF and a toluene solution (10 mL) of Lu-
(CH2SiMe3)3(thf)2 (0.580 g, 1.0 mmol) was added 1 equiv of ligand
L2(iPr) (0.482 g, 1.0 mmol) slowly at room temperature. The mixture
was stirred for 7 h to afford a yellow solution. Evaporation of the
solvent left a mixture of complexes 4a and 4b as yellow crystalline
solids. Recrystallization from a mixture of toluene and hexane at −30
°C within 12 h first gave pure complex 4a as yellow crystalline solids in
high yield (0.312 g); then the remaining mother liquor was further
1
of ligand L3(Me) (0.419 g, 1.0 mmol) in a 53% yield (0.401 g). H
NMR (600 MHz, C6D6, 7.16 ppm, 25 °C): δ −1.07 (d, 2JHH = 6.0 Hz,
2H, YCH2SiMe3), −0.70 (d, 2JHH = 6.0 Hz, 2H, YCH2SiMe3), 0.35 (s,
18H, CH2SiMe3), 1.10 (br s, 4H, thf), 2.10 (s, 6H, Ar−CH3), 3.50 (br
s, 4H, thf), 6.78−6.80 (m, 1H, Ar-H), 6.84 (d, 3JHH = 6.0 Hz, 2H, Ar-
H), 6.87−6.90 (m, 2H, Ar-H), 7.00−7.08 (m, 4H, Ar-H), 7.16 (s, 1H,
Ar-H), 7.18 (t, 3JHH = 6.0 Hz, 1H, Ar-H), 7.24 (t, 3JHH = 12.0 Hz, 1H,
4278
dx.doi.org/10.1021/om300263p | Organometallics 2012, 31, 4267−4282

Organometallics
Article
3
Ar-H), 7.31 (t, JHH = 6.0 Hz, 1H, Ar-H), 7.38−7.41 (m, 2H, Ar-H),
(600 MHz, C6D6, 7.16 ppm, 25 °C): δ 0.10 (br s, 10H, ScCH2SiMe3
and Ar−CH(CH3)2), 0.47 (br s, 18H, CH2SiMe3), 1.03 (s, 3H, Ar−
CH(CH3)2), 1.33 (s, 3H, Ar−CH(CH3)2), 3.44 (br s, 1H, Ar−
CH(CH3)2), 3.95 (br s, 1H, Ar−CH(CH3)2), 6.86 (br s, 2H, Ar-H),
6.99−7.10 (m, 10H, Ar-H), 7.17−7.22 (m, 3H, Ar-H), 7.60−7.62 (m,
3H, Ar-H), 7.79 (t, 3JHH = 6.0 Hz, 1H, Ar-H), 7.83 ppm (d, 3JHH = 6.0
Hz, 1H, Ar-H). 13C NMR (150 MHz, C6D6, 128.06 ppm, 25 °C): δ
3.68 (s, 6C, CH2SiMe3), 23.44, 24.32, 25.51, 26.61, 27.24, 28.50 (s, 6C,
Ar−CH(CH3)2 and Ar-CH(CH3)2), 43.59 (br s, 1C, ScCH2SiMe3),
46.93 (br s, 1C, ScCH2SiMe3), 76.53 (d, JPC = 123.0 Hz, 1C, Ind-C),
109.62 (d, 2JPC = 10.5 Hz, 1C, Ind-C), 123.62 (s, 1C, Ar-C), 124.22 (s,
1C, Ar-C), 124.68 (s, 1C, Ar-C), 125.20 (d, 2JPC = 15.0 Hz, 2C, Ar-C),
125.46 (s, 1C, Ar-C), 125.78 (s, 1C, Ar-C), 126.58 (d, 3JPC = 13.5 Hz,
3
7.46 (d, JHH = 6.0 Hz, 1H, Ar-H), 7.56−7.59 (m, 2H, Ar-H), 7.87
ppm (d, JHH = 12.0 Hz, 1H, Ar-H). 13C NMR (150 MHz, C6D6,
3
128.06 ppm, 25 °C): δ 4.57 (s, 6C, CH2SiMe3), 22.75 (s, 2C, Ar-CH3),
36.39 (d, JYC = 39.0 Hz, 2C, YCH2SiMe3), 25.02 (br s, 2C, thf), 69.90
(br s, 2C, thf), 75.59 (d, JPC = 130.5 Hz, 1C, Ind-C), 110.87 (d, 2JPC
=
12.0 Hz, 1C, Ind-C), 121.58 (s, 1C, Ar-C), 122.44 (s, 1C, Ar-C),
122.80 (s, 1C, Ar-C), 123.45 (s, 1C, Ar-C), 124.40 (s, 1C, Ar-C),
125.48 (d, 3JPC = 13.5 Hz, 1C, Ind-C), 128.35 (s, 2C, Ar-C), 128.40 (s,
1C, Ar-C), 128.85 (d, 3JPC = 12.0 Hz, 2C, Ar-C), 129.44 (d, 3JPC = 3.0
Hz, 2C, Ar-C), 132.15 (d, 2JPC = 7.5 Hz, 2C, Ar-C), 132.42 (s, 2C, Ar-
C), 132.71 (s, 1C, Ar-C), 132.87 (d, JPC = 9.0 Hz, 2C, Ar-C), 133.30
(d, JPC = 10.5 Hz, 2C, Ar-C), 135.13 (d, JPC = 6.0 Hz, 1C, Ar-C),
136.67 (d, JPC = 10.5 Hz, 1C, Ar-C), 145.86 ppm (d, JPC = 7.5 Hz,
1C, Ar-C). 31P NMR (162 MHz, C6D6, 25 °C): δ 6.34 ppm (s). Anal.
Calcd for C41H55ONPSi2Y: C, 65.32; H, 7.35; N, 1.86. Found: C,
65.53; H, 7.24; N, 1.74.
2
3
2
3
2
3
1C, Ind-C), 128.45 (s, 2C, Ar-C), 129.15 (d, JPC = 12.0 Hz, 2C, Ar-
C), 130.53 (s, 1C, Ar-C), 131.20 (s, 1C, Ar-C), 132.71 (s, 2C, Ar-C),
2
132.95 (s, 2C, Ar-C), 133.16 (d, JPC = 9.0 Hz, 2C, Ar-C), 134.48 (d,
2
3JPC = 10.5 Hz, 2C, Ar-C), 135.15 (d, JPC = 13.5 Hz, 1C, Ar-C),
139.33 (d, 3JPC = 9.0 Hz, 1C, Ar-C), 145.64 (br s, 1C, Ar-C). 31P NMR
(162 MHz, C6D6, 25 °C): δ 10.13 ppm (s). Anal. Calcd for
C41H55NPSi2Sc: C, 70.96; H, 7.99; N, 2.02. Found: C, 71.34; H, 7.87;
N, 1.94.
Synthesis of the Complex (Ind−PPh2N−C6H3Me2)Lu-
(CH2SiMe3)2(thf) (5c). Following a similar procedure described for
the preparation of complex 1, complex 5c was isolated from the acid−
base reaction of Lu(CH2SiMe3)3(thf)2 (0.580 g, 1.0 mmol) with 1
equiv of ligand L3(Me) (0.419 g, 1.0 mmol) in a 50% yield (0.424 g).
1H NMR (600 MHz, C6D6, 7.16 ppm, 25 °C): δ −0.72 (d, 2JHH = 12.0
i
Synthesis of the Complex (Ind−PPh2N−C6H3 Pr2)Y-
(CH2SiMe3)2(thf) (7b). Following a similar procedure described for
the preparation of complex 1, complex 7b was isolated from the acid−
base reaction of Y(CH2SiMe3)3(thf)2 (0.495 g, 1.0 mmol) with 1 equiv
Hz, 2H, LuCH2SiMe3), −0.58 (d, 2JHH = 12.0 Hz, 2H, LuCH2SiMe3),
0.27 (s, 18H, CH2SiMe3), 1.24 (br s, 4H, thf), 2.31 (s, 6H, Ar−CH3),
3.40 (br s, 4H, thf), 6.85−7.14 (m, 12H, Ar-H), 7.26 (t, 3JHH = 6.0 Hz,
1H, Ar-H), 7.33 (d, 3JHH = 6.0 Hz, 1H, Ar-H), 7.39−7.43 (m, 4H, Ar-
1
of ligand L3(iPr) (0.475 g, 1.0 mmol) in a 46% yield (0.371 g). H
NMR (600 MHz, C6D6, 7.16 ppm, 25 °C): δ −0.89 (br s, 2H,
YCH2SiMe3), −0.54 (br s, 2H, YCH2SiMe3), 0.35 (s, 18H,
CH2SiMe3), 0.63 (br s, 4H, thf), 1.18 (s, 12H, Ar−CH(CH3)2), 3.51
(s, 4H, thf), 3.69 (br s, 2H, Ar−CH(CH3)2), 6.84−6.87 (m, 2H, Ar-
H), 7.73 ppm (d, JHH = 6.0 Hz, 1H, Ar-H). 13C NMR (150 MHz,
3
C6D6, 128.06 ppm, 25 °C): δ 4.44 (s, 6C, CH2SiMe3), 22.45 (s, 2C,
Ar-CH3), 25.28 (br s, 2C, thf), 44.73 (s, 2C, LuCH2SiMe3), 69.46 (br
s, 2C, thf), 72.64 (d, JPC = 121.5 Hz, 1C, Ind-C), 114.28 (br s, 1C, Ar-
C), 118.94 (d, 2JPC = 7.5 Hz, 1C, Ind-C), 121.40 (s, 1C, Ar-C), 122.48
(s, 1C, Ar-C), 122.79 (s, 1C, Ar-C), 124.32 (s, 2C, Ar-C), 128.35 (s,
2C, Ar-C), 128.75 (d, 3JPC = 12.0 Hz, 2C, Ar-C), 129.73 (s, 2C, Ar-C),
130.99 (s, 1C, Ar-C), 131.61 (s, 1C, Ar-C), 132.13 (s, 1C, Ar-C),
3
H), 6.97−7.10 (m, 10H, Ar-H), 7.22 (t, JHH = 12.0 Hz, 2H, Ar-H),
7.30 (br s, 2H, Ar-H), 7.54 (br s, 2H, Ar-H), 7.83 ppm (d, 3JHH = 12.0
Hz, 1H, Ar-H). 13C NMR (150 MHz, C6D6, 128.06 ppm, 25 °C): δ
4.48 (s, 6C, CH2SiMe3), 25.20 (s, 4C, Ar−CH(CH3)2), 25.75 (br s,
2C, thf), 28.51 (s, 2C, Ar-CH(CH3)2), 37.30 (d, JYC = 43.5 Hz, 2C,
YCH2SiMe3), 69.97 (s, 2C, thf), 75.60 (d, JPC = 129.0 Hz, 1C, Ind-C),
111.22 (br s, 1C, Ind-C), 121.05 (s, 1C, Ar-C), 122.61 (s, 1C, Ar-C),
122.73 (s, 1C, Ar-C), 124.36 (s, 1C, Ar-C), 124.72 (s, 1C, Ar-C),
124.88 (s, 2C, Ar-C), 126.74 (d, 3JPC = 12.0 Hz, 1C, Ind-C), 128.35 (s,
2C, Ar-C), 128.43 (s, 1C, Ar-C), 128.90 (d, 3JPC = 10.5 Hz, 2C, Ar-C),
131.80 (s, 1C, Ar-C), 132.17 (s, 2C, Ar-C), 132.45 (s, 2C, Ar-C),
133.39 (d, 2JPC = 9.0 Hz, 2C, Ar-C), 133.58 (d, 3JPC = 9.0 Hz, 2C, Ar-
C), 137.07 (d, 2JPC = 12.0 Hz, 1C, Ar-C), 141.53 (d, 3JPC = 9.0 Hz, 1C,
Ar-C), 145.81 (br s, 1C, Ar-C). Anal. Calcd for C45H63ONPSi2Y: C,
66.72; H, 7.84; N, 1.73. Found: C, 67.13; H, 7.69; N, 1.67.
2
132.19 (s, 1C, Ar-C), 132.39 (s, 1C, Ar-C), 132.96 (d, JPC = 9.0 Hz,
2C, Ar-C), 133.07 (d, 3JPC = 10.5 Hz, 2C, Ar-C), 135.65 (d, 2JPC = 6.0
Hz, 2C, Ar-C), 138.67 (br s, 1C, Ar-C), 143.88 ppm (d, 2JPC = 7.5 Hz,
1C, Ar-C). 31P NMR (162 MHz, C6D6, 25 °C): δ 9.15 ppm (s). Anal.
Calcd for C41H55ONPSi2Lu: C, 58.62; H, 6.60; N, 1.67. Found: C,
58.98; H, 6.44; N, 1.61.
Synthesis of the Complex (Ind−PPh2N−C6H3Et2)Sc-
(CH2SiMe3)2 (6). Following a similar procedure described for the
preparation of complex 1, complex 6 was isolated from the acid−base
reaction of Sc(CH2SiMe3)3(thf)2 (0.451 g, 1.0 mmol) with 1 equiv of
ligand L3(Et) (0.447 g, 1.0 mmol) in a 43% yield (0.290 g). 1H NMR
(600 MHz, C6D6, 7.16 ppm, 25 °C): δ 0.17 (s, 4H, ScCH2SiMe3), 0.24
i
Synthesis of the Complex (Ind−PPh2N−C6H3 Pr2)Lu-
(CH2SiMe3)2(thf) (7c). Following a similar procedure described for
the preparation of complex 1, complex 7c was isolated from the acid−
base reaction of Lu(CH2SiMe3)3(thf)2 (0.580 g, 1.0 mmol) with 1
equiv of ligand L3(iPr) (0.475 g, 1.0 mmol) in a 55% yield (0.491 g).
1H NMR (600 MHz, C6D6, 7.16 ppm, 25 °C): δ −0.60 (br s, 2H,
LuCH2SiMe3), −0.41 (br s, 2H, LuCH2SiMe3), 0.31 (s, 18H,
CH2SiMe3), 0.49 (br s, 6H, Ar−CH(CH3)2), 1.17 (s, 4H, thf), 1.42
(br s, 6H, Ar−CH(CH3)2), 3.37 (s, 4H, thf), 3.93 (br s, 2H, Ar−
CH(CH3)2), 6.90−7.11 (m, 14H, Ar-H), 7.29 (very br s, 4H, Ar-H),
7.72 ppm (d, 3JHH = 12.0 Hz, 1H, Ar-H). 13C NMR (150 MHz, C6D6,
128.06 ppm, 25 °C): δ 4.44 (s, 6C, CH2SiMe3), 23.73 (br s, 2C, Ar−
CH(CH3)2), 25.19 (s, 2C, thf), 26.58 (br s, 2C, Ar−CH(CH3)2),
28.61 (s, 2C, Ar-CH(CH3)2), 45.58 (s, 2C, LuCH2SiMe3), 69.89 (s,
2C, thf), 73.13 (d, JPC = 121.5 Hz, 1C, Ind-C), 114.64 (br s, 1C, Ind-
C), 119.09 (s, 1C, Ar-C), 121.52 (s, 1C, Ar-C), 122.34 (s, 1C, Ar-C),
122.87 (s, 1C, Ar-C), 124.98 (s, 3C, Ar-C), 125.14 (s, 2C, Ar-C),
128.35 (s, 2C, Ar-C), 128.90 (d, 3JPC = 12.0 Hz, 2C, Ar-C), 131.22 (s,
1C, Ar-C), 131.79 (s, 2C, Ar-C), 132.10 (s, 2C, Ar-C), 132.38 (s, 2C,
3
(br s, 18H, CH2SiMe3), 0.91 (t, JHH = 12.0 Hz, 6H, Ar−CH2CH3),
1.23−1.27 (m, 2H, Ar−CH2CH3), 2.75−2.79 (m, 2H, Ar−CH2CH3),
6.85−7.08 (m, 11H, Ar-H), 7.20 (t, 3JHH = 6.0 Hz, 1H, Ar-H), 7.24 (t,
3JHH = 6.0 Hz, 1H, Ar-H), 7.46−7.62 (m, 5H, Ar-H), 7.81 ppm (d,
3JHH = 6.0 Hz, 1H, Ar-H). 13C NMR (150 MHz, C6D6, 128.06 ppm, 25
°C): δ 3.75 (s, 6C, CH2SiMe3), 25.09 (s, 2C, Ar−CH2CH3), 44.77 (br
s, 2C, ScCH2SiMe3), 50.46 (s, 2C, Ar-CH2CH3), 75.72 (d, JPC = 129.0
Hz, 1C, Ind-C), 109.84 (d, 2JPC = 12.0 Hz, 1C, Ind-C), 121.29 (s, 1C,
Ar-C), 123.03 (s, 1C, Ar-C), 123.32 (s, 1C, Ar-C), 123.77 (s, 1C, Ar-
C), 124.38 (s, 1C, Ar-C), 124.62 (s, 2C, Ar-C), 125.86 (d, 3JPC = 13.5
3
Hz, 1C, Ind-C), 128.35 (s, 2C, Ar-C), 128.49 (d, JPC = 12.0 Hz, 2C,
2
Ar-C), 129.03 (d, JPC = 12.0 Hz, 2C, Ar-C), 129.89 (s, 2C, Ar-C),
131.71 (s, 1C, Ar-C), 132.40 (d, 2JPC = 10.5 Hz, 2C, Ar-C), 132.86 (s,
1C, Ar-C), 133.58 (d, 3JPC = 10.5 Hz, 2C, Ar-C), 134.82 (d, 3JPC = 12.0
2
Hz, 1C, Ar-C), 138.41 (s, 1C, Ar-C), 141.39 ppm (d, JPC = 9.0 Hz,
1C, Ar-C). 31P NMR (162 MHz, C6D6, 25 °C): δ 7.03 ppm (s). Anal.
Calcd for C39H51NPSi2Sc: C, 70.34; H, 7.72; N, 2.10. Found: C, 70.76;
H, 7.61; N, 2.01.
2
Ar-C), 133.44 (d, JPC = 6.0 Hz, 2C, Ar-C), 138.75 (br s, 1C, Ar-C),
i
Synthesis of the Complex (Ind−PPh2N−C6H3 Pr2)Sc-
140.51 (d, 3JPC = 9.0 Hz, 1C, Ar-C), 146.22 (s, 1C, Ar-C). Anal. Calcd
for C45H63ONPSi2Lu: C, 60.31; H, 7.09; N, 1.56. Found: C, 60.73; H,
6.99; N, 1.50.
(CH2SiMe3)2 (7a). Following a similar procedure described for the
preparation of complex 1, complex 7a was isolated from the acid−base
reaction of Sc(CH2SiMe3)3(thf)2 (0.451 g, 1.0 mmol) with 1 equiv of
ligand L3(iPr) (0.475 g, 1.0 mmol) in a 50% yield (0.349 g). 1H NMR
Synthesis of the Complex [(η1-Flu)−PPh2N−C6H5]Sc-
(CH2SiMe3)2(thf) (8). Following a similar procedure described for
4279
dx.doi.org/10.1021/om300263p | Organometallics 2012, 31, 4267−4282

Organometallics
Article
the preparation of complex 1, complex 8 was isolated from the acid−
base reaction of Sc(CH2SiMe3)3(thf)2 (0.451 g, 1.0 mmol) with 1
equiv of ligand L4(H) (0.442 g, 1.0 mmol) in a 55% yield (0.401 g).
1H NMR (600 MHz, C6D6, 7.16 ppm, 25 °C): δ 0.29 (d, 2JHH = 12.0
Ethylene Polymerization. A detailed polymerization procedure is
described as a typical example (Table 1, run 5). In a glovebox, a
toluene solution (30 mL) of complex 2a (6.4 mg, 10 μmol) was
charged into a two-neck flask with a magnetic stir bar. The flask was
taken outside of the glovebox and set in a water bath and connected to
a well-purged Schlenk ethylene line with a mercury-sealed stopper by
use of a three-way cock. Ethylene (1.0 bar) was introduced into the
system and was saturated in the solution at 50 °C by stirring for 5 min.
The toluene solution of [Ph3C][B(C6F5)4] (9.2 mg, 10 μmol) and
AliBu3 (0.1 mL, 100 μmol, 1.0 M in toluene) was then added through
a syringe under vigorous stirring. The mixture was stirred under
constant ethylene pressure (1.0 bar) for 5 min. After that, methanol (2
mL) was added to terminate the reaction. The reaction mixture was
added to acidified methanol (20 mL of concentrated HCl in 500 mL of
ethanol). Polyethylene was obtained by filtration, washed with
methanol, and dried at 40 °C for 24 h in vacuum.
Hz, 2H, ScCH2SiMe3), 0.36 (s, 18H, CH2SiMe3), 0.59 (d, 2JHH = 12.0
Hz, 2H, ScCH2SiMe3), 0.86 (br s, 4H, thf), 2.53 (br s, 4H, thf), 6.83−
6.86 (m, 4H, Ar-H), 6.92−6.96 (m, 3H, Ar-H), 6.98 (d, 3JHH = 6.0 Hz,
2H, Ar-H), 7.07−7.12 (m, 4H, Ar-H), 7.23 (t, 3JHH = 18.0 Hz, 2H, Ar-
H), 7.61−7.64 (m, 4H, Ar-H), 7.76 (d, 3JHH = 6.0 Hz, 2H, Ar-H), 7.94
ppm (d, 3JHH = 6.0 Hz, 2H, Ar-H). 13C NMR (150 MHz, C6D6, 128.06
ppm, 25 °C): δ 3.99 (s, 6C, CH2SiMe3), 24.93 (s, 2C, thf), 46.32 (br s,
2C, CH2SiMe3), 59.14 (d, JPC = 108.0 Hz, 1C, Flu-C), 71.55 (s, 2C,
thf), 119.73 (s, 2C, Ar-C), 119.90 (s, 2C, Ar-C), 120.83 (s, 2C, Ar-C),
122.15 (s, 1C, Ar-C), 124.58 (d, 2JPC = 14.5 Hz, 2C, Ar-C), 125.45 (s,
2C, Ar-C), 128.57 (s, 1C, Ar-C), 128.88 (d, 2JPC = 12.0 Hz, 4C, Ar-C),
129.18 (s, 2C, Ar-C), 129.67 (s, 1C, Ar-C), 132.18 (s, 2C, Ar-C),
133.65 (d, 2JPC = 9.0 Hz, 4C, Ar-C), 134.90 (d, 3JPC = 10.5 Hz, 2C, Ar-
C), 141.32 (d, 2JPC = 9.0 Hz, 2C, Ar-C), 147.87 ppm (d, 2JPC = 4.5 Hz,
1C, Ar-C). 31P NMR (162 MHz, C6D6, 25 °C): δ 11.53 ppm (s). Anal.
Calcd for C43H53NPOSi2Sc: C, 70.56; H, 7.30; N, 1.91. Found: C,
71.04; H, 7.38; N, 1.84.
CCDC-851548 (1), 851549 (2a), 857591 (2b), 872989 (2d),
791780 (2e), 851550 (3a), 851551 (3b), 851552 (4b), 851553 (5b),
851554 (6), 851555 (7a), 851556 (L2(iPr)), and 670404 (9b) contain
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.
Synthesis of the Complex [(η1-Flu)−PPh2N−C6H4Me]Sc-
(CH2SiMe3)2(thf) (9a). Following a similar procedure described for
the preparation of complex 1, complex 9a was isolated from the acid−
base reaction of Sc(CH2SiMe3)3(thf)2 (0.451 g, 1.0 mmol) with 1
equiv of ligand L4(Me) (0.454 g, 1.0 mmol) in a 48% yield (0.357 g).
ASSOCIATED CONTENT
■
S
* Supporting Information
1H and 13C NMR spectra of all complexes, 1H NMR spectra of
polyethylene, and the crystallographic data and structure
refinement details for complexes 1−9. This material is available
free of charge via the Internet at http://pubs.acs.org.
1H NMR (600 MHz, C6D6, 7.16 ppm, 25 °C): δ 0.30 (d, 2JHH = 12.0
2
Hz, 2H, ScCH2SiMe3), 0.37 (br s, 18H, CH2SiMe3), 0.60 (d, JHH
=
12.0 Hz, 2H, ScCH2SiMe3), 0.86 (br s, 4H, thf), 2.13 (s, 3H, Ar−
3
CH3), 2.53 (br s, 4H, thf), 6.85−6.88 (m, 4H, Ar-H), 6.95 (t, JHH
=
12.0 Hz, 2H, Ar-H), 7.00 (d, 3JHH = 6.0 Hz, 2H, Ar-H), 7.07−7.12 (m,
6H, Ar-H), 7.63−7.66 (m, 4H, Ar-H), 7.69 (d, 3JHH = 6.0 Hz, 2H, Ar-
AUTHOR INFORMATION
Corresponding Author
■
H), 7.95 ppm (d, JHH = 6.0 Hz, 2H, Ar-H). 13C NMR (150 MHz,
3
C6D6, 128.06 ppm, 25 °C): δ 4.02 (s, 6C, CH2SiMe3), 20.75 (s, 1C,
Ar-CH3), 24.93 (s, 2C, thf), 46.28 (br s, 2C, CH2SiMe3), 59.17 (d, JPC
= 108.0 Hz, 1C, Flu-C), 71.53 (s, 2C, thf), 119.75 (s, 2C, Ar-C),
119.88 (s, 2C, Ar-C), 120.77 (s, 2C, Ar-C), 124.48 (d, 2JPC = 14.5 Hz,
2C, Ar-C), 125.43 (s, 2C, Ar-C), 128.85 (d, 2JPC = 12.0 Hz, 4C, Ar-C),
129.33 (s, 1C, Ar-C), 129.80 (s, 2C, Ar-C), 129.89 (s, 1C, Ar-C),
*E-mail: dmcui@ciac.jl.cn (D.C.), jsu@staff.uni-marburg.de
(J.S.). Fax: (+86) 431 85262774 (D.C.), +49 (0)6421
2825711 (J.S.). Tel: +86 431 85262773 (D.C.), +49 (0)6421
2825693 (J.S.).
Author Contributions
⊥The authors contributed equally to this work.
2
131.21 (s, 1C, Ar-C), 132.13 (s, 2C, Ar-C), 133.71 (d, JPC = 9.0 Hz,
4C, Ar-C), 134.87 (d, 3JPC = 10.5 Hz, 2C, Ar-C), 141.39 (d, 2JPC = 9.0
Notes
2
Hz, 2C, Ar-C), 145.26 ppm (d, JPC = 4.5 Hz, 1C, Ar-C). 31P NMR
The authors declare no competing financial interest.
(162 MHz, C6D6, 25 °C): δ 11.27 ppm (s). Anal. Calcd for
C44H55NPOSi2Sc: C, 70.84; H, 7.43; N, 1.88. Found: C, 71.23; H,
7.54; N, 1.76.
ACKNOWLEDGMENTS
■
Synthesis of the Complex [(η1-Flu)−PPh2N−C6H4Me]Lu-
(CH2SiMe3)2(thf) (9b). Following a similar procedure described for
the preparation of complex 1, complex 9b was isolated from the acid−
base reaction of Lu(CH2SiMe3)3(thf)2 (0.580 g, 1.0 mmol) with 1
equiv of ligand L4(Me) (0.454 g, 1.0 mmol) in a 43% yield (0.381 g).
1H NMR (600 MHz, C6D6, 7.16 ppm, 25 °C): δ −0.25 and −0.36
This work was supported by The National Natural Science
Foundation of China for projects Nos. 20934006, 51073148,
and 51021003 and The Ministry of Science and Technology of
China for project No. 2011DFR50650. In addition, this work
was also supported by Deutsche Forschungsgemeinschaft
Priority Program “Lanthanoide specific functionality” Su 127/
8-2. K.A.R. thanks Deutsche Akademischer Austausch Dienst
(DAAD) for funding of a research fellowship at Philipps-
(overlapped s, 4H, LuCH2SiMe3), 0.36 (br s, 18H, CH2SiMe3), 0.88
(br s, 4H, thf), 2.10 (s, 3H, Ar−CH3), 2.44 (br s, 4H, thf), 6.86−6.89
(m, 4H, Ar-H), 6.97 (t, 3JHH = 18.0 Hz, 2H, Ar-H), 7.02 (t, 3JHH = 18.0
Hz, 4H, Ar-H), 7.10 (t, 3JHH = 12.0 Hz, 2H, Ar-H), 7.17 (t, 3JHH = 12.0
Hz, 2H, Ar-H), 7.53 (d, 3JHH = 6.0 Hz, 2H, Ar-H), 7.61−7.65 (m, 4H,
Ar-H), 7.96 ppm (d, 3JHH = 6.0 Hz, 2H, Ar-H). 13C NMR (150 MHz,
C6D6, 128.06 ppm, 25 °C): δ 4.56 (s, 6C, CH2SiMe3), 20.74 (s, 1C,
Ar-CH3), 25.12 (br s, 2C, thf), 44.21 (br s, 1C, CH2SiMe3), 60.65 (d,
JPC = 114.0 Hz, 1C, Flu-C), 70.33 (br s, 2C, thf), 118.32 (s, 2C, Ar-C),
119.97 (s, 2C, Ar-C), 120.39 (s, 2C, Ar-C), 124.50 (d, 2JPC = 14.5 Hz,
2C, Ar-C), 125.85 (s, 2C, Ar-C), 128.93 (d, 2JPC = 10.5 Hz, 4C, Ar-C),
129.89 (s, 1C, Ar-C), 130.00 (s, 2C, Ar-C), 130.45 (s, 1C, Ar-C),
131.20 (s, 1C, Ar-C), 132.24 (s, 2C, Ar-C), 133.48 (d, 2JPC = 10.5 Hz,
4C, Ar-C), 134.08 (d, 3JPC = 10.5 Hz, 2C, Ar-C), 140.61 (d, 2JPC = 9.0
Universitat Marburg within the Ostpatnerschaftsprogramm.
̈
N.K.H. thanks Studienstiftung des deutschen Volkes for a
fellowship.
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