Rare-earth metal alkyl and hydride complexes supported by a linked anilido-cyclopentadienyl ligand: Synthesis, structure, and reactivity

Article abstract of DOI:10.1002/ejic.200800216

Trimethylsilylmethyl complexes of the type [Ln(η⁵-C ₅Me₄CH₂SiMe₂NC₆H ₄R-4-κN)(CH₂SiMe₃)(thf)_n] containing a dianionic ligand [C₅Me₄CH ₂SiMe₂NC₆H₄R-4]^2- with a para-substituted anilido group and a CH₂SiMe₂ link were prepared. The yttrium complex [Y(η⁵-C₅Me ₄CH₂SiMe₂NPh-κN)(CH₂SiMe ₃)(thf)₂] (2a) reacts with H₂ to generate the corresponding dimeric hydride [Y(η⁵-C₅Me ₄CH₂SiMe₂NPh-κN)-(μ-H)(thf)] ₂ (5a). Pyridine inserts into the Y-H bond in a 1,2-fashion to afford the stable 2-hydropyridyl complex [Y(η⁵-C₅Me ₄CH₂SiMe₂NPh-κN)(η¹- NC₅H₆)(py)₂] (6a). Upon reaction with tBuC≡CH, protonolysis takes place to give the dimeric alkynyl complex [Y(η⁵-C₅Me₄CH₂SiMe ₂NPh-κN)(μ-C≡CtBu)(thf)]₂ (7a). Wiley-VCH Verlag GmbH & Co. KGaA, 2008.

Full text of DOI:10.1002/ejic.200800216

FULL PAPER
DOI: 10.1002/ejic.200800216
Rare-Earth Metal Alkyl and Hydride Complexes Supported by a Linked
Anilido–cyclopentadienyl Ligand: Synthesis, Structure, and Reactivity
Dominique Robert,[a] Peter Voth,[a] Thomas P. Spaniol,[a] and Jun Okuda*[a]
Keywords: Rare-earth metals / Half-sandwich complexes / Alkyl complexes / Hydride complexes / Pyridine / Alkyne
Trimethylsilylmethyl complexes of the type [Ln(η5-
C5Me4CH2SiMe2NC6H4R-4-κN)(CH2SiMe3)(thf)n] contain-
ing a dianionic ligand [C5Me4CH2SiMe2NC6H4R-4]2– with a
para-substituted anilido group and a CH2SiMe2 link were
prepared. The yttrium complex [Y(η5-C5Me4CH2SiMe2NPh-
κN)(CH2SiMe3)(thf)2] (2a) reacts with H2 to generate the cor-
responding dimeric hydride [Y(η5-C5Me4CH2SiMe2NPh-κN)-
(µ-H)(thf)]2 (5a). Pyridine inserts into the Y–H bond in a 1,2-
fashion to afford the stable 2-hydropyridyl complex [Y(η5-
C5Me4CH2SiMe2NPh-κN)(η1-NC5H6)(py)2] (6a). Upon reac-
tion with tBuCϵCH, protonolysis takes place to give the di-
meric alkynyl complex [Y(η5-C5Me4CH2SiMe2NPh-κN)(µ-
CϵCtBu)(thf)]2 (7a).
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
Introduction
Results and Discussion
Linked amido–cyclopentadienyl ligands (C5R4ZNRЈ)2–,
commonly known as “constrained geometry ligands”, have
gained considerable importance as ancillary ligands for
group 4 metal polymerization catalyst precursors.[1] Since
the first report on scandium alkyl and hydride complexes
containing a linked tert-butylamido tetramethylcyclopen-
tadienyl ligand by Bercaw et al.,[2] this type of chelate li-
gands have also been utilized widely in group 3 metal chem-
istry.[3,4d–4h,11] Work by Hou et al. suggests that the anilido
group rather than the ubiquitous tert-butylamido group for
the amido donor RЈ imparts a higher activity to the metal
center in alkyne dimerization catalysis and related reac-
tions,[5b,10] probably because of the electron-withdrawing
property of the phenyl group in conjunction with a different
steric profile. We have recently reported that yttrium hy-
dride complexes supported by a linked amido–cyclopen-
tadienyl ligand [Ln(η5-C5Me4ZNRЈ-κN)(µ-H)(thf)n]2 (Ln =
Y, Lu) are active hydrosilylation catalysts for 1-alkene and
styrene and that the amido substituent RЈ as well as the
link Z exert considerable influence on both activity and re-
gioselectivity; the longer CH2SiMe2 link delivers the most-
active catalyst.[5] We report here on the synthesis, structure,
and reactivity of yttrium hydride complexes that contain a
CH2SiMe2-linked anilido–cyclopentadienyl ligand.
Alkyl Complexes
The trimethylsilylmethyl complexes [Ln(η5-C5Me4CH2-
SiMe2NC6H4R-4-κN)(CH2SiMe3)(thf)n] [Ln = Y, n = 2: R
= H (2a), tBu (2b), nBu (2c); Ln = Lu, n = 2: R = H (3a);
n = 1.5: R = tBu (3b), nBu (3c)] were synthesized by adding
the diprotonated ligand [(C5Me4H)CH2SiMe2NHC6H4R-4]
to a suspension of [Ln(CH2SiMe3)3(thf)2] in pentane cooled
to –78 °C and isolated as colorless powders (Scheme 1).
Complexes 2a and 3a containing an anilido group are
sparingly soluble in aliphatic hydrocarbon solvents, but sol-
1
uble in aromatic solvents. The H NMR spectra at room
temperature show five singlets for the methyl groups at-
tached to the silicon atoms (SiMe3, SiMe2), for those on the
cyclopentadienyl ring, and for the methylene group of the
linker. The methylene group attached to the yttrium center
in 2a gives rise to a doublet at δ = –0.91 ppm (2JYH
=
2.7 Hz), whilst a sharp singlet is observed at δ = –0.84 ppm
for the corresponding signal in the lutetium complex 3a.
Three signals are detected for the protons at the phenyl ring
with an integral ratio of 1:2:2, which indicates free rotation
of the ring about the C–N single bond. This rotation is
slowed down by cooling, as five distinct signals are ob-
served at –70 °C. Two separate signals for the α- and the β
protons of thf are found at this temperature, whereas the
signals arising from the diastereotopic groups of the anil-
ido–cyclopentadienyl ligand do not split. The Cs symmetry
is due to the trans coordination of two thf molecules.
Crystals of 2a suitable for diffraction were obtained from
a saturated toluene solution at –30 °C, and Figure 1 shows
two views of the molecule. The compound was found to
[a] Institute of Inorganic Chemistry, RWTH Aachen University,
Landoltweg 1, 52074 Aachen, Germany
Fax: +49-241-80-92644
E-mail: jun.okuda@ac.rwth-aachen.de.
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Rare-Earth Metal Alkyl and Hydride Complexes
Scheme 1.
adopt a distorted square-pyramidal coordination geometry
Comparison with an analogous complex featuring a
in the solid state; two molecules of thf, the alkyl group, and shorter SiMe2 link, [Y(η5-C5Me4SiMe2NPh-κN)(CH2Si-
the nitrogen atom form the base of the structure.
Me3)(thf)2] (A),[10] illustrates the influence of the ligand on
the molecular geometry around the metal center (Figure 2).
The additional carbon atom in the backbone of 2a induces
a much smaller N–Y–C(alkyl) angle [140.8(2)° in 2a vs.
150.89(19)° in A], together with a smaller Y–N–Cipso angle
[115.5(4)° in 2a vs. 131.0(4)° in A]. Consequently, the plane
Figure 1. ORTEP view of the alkyl complex [Y(η5-C5Me4CH2Si-
Me2NPh-κN)(CH2SiMe3)(thf)2] (2a) (left: standard view; right: top
view). Thermal ellipsoids are drawn at the 50% probability level.
Hydrogen atoms are omitted for clarity. Selected bond lengths [Å]
and angles [°]: Y–N 2.312(5), Y–C19 2.451(6), Y–O1 2.428(4), Y–
O2 2.419(4), Y–Cpcent 2.342(6), N–C13 1.382(8); N–Y–O1
83.77(16), N–Y–O2 83.02(16), O1–Y–O2 145.05(15), N–Y–C19
140.8(2).
The phenyl ring is arranged parallel to the plane defined
by the Si, N, and Y atoms. The bulky SiMe3 group is bent
away from the cyclopentadienyl ring (Cpcent–Y–C19–Si2
179°). In other four-coordinate linked amido–cyclopen-
tadienyl
complexes
such
as
[Y(η5-C5Me4CH2Si-
Me2NCH2CH2NMe2-κN,NЈ)(CH2SiMe3)(thf)] (Cpcent–Y–
C–Si 89°),[6] [Y(η5-C5Me4SiMe2NtBu-κN)(CH2SiMe3)(thf)]
(Cpcent–Y–C–Si 90.1°),[7] or [Y(η5-C5Me4CH2SiMe2NtBu-
κN)(CH2SiMe3)(thf)] (Cpcent–Y–C–Si 94.1°), this group is
found to be turned to the side.[5a] The Y–Cring and Y–O
bonding distances are in the usual range for yttrium amido–
cyclopentadienyl complexes. The Y–N bond length of
2.312(5) Å is long and comparable to bimetallic rare-earth
Figure 2. Comparison of structural parameters in [Y(η5-C5Me4Si-
Me2NPh-κN)(CH2SiMe3)(thf)2][10] (A, top) and in [Y(η5-
C5Me4CH2SiMe2NPh-κN)(CH2SiMe3)(thf)2] (2a, bottom).
Table 1. Selected bond lengths [Å] in [Y(η5-C5Me4SiMe2NPh-
κN)(CH2SiMe3)(thf)2][10] (A) and in [Y(η5-C5Me4CH2SiMe2NPh-
κN)(CH2SiMe3)(thf)2] (2a).
metal
complexes of
the type
[LiY(η5-C5R4Si-
Me2NCH2CH2X-κN)2] (C5R4 = C5Me4, C5H3tBu; X =
NMe2, OMe),[4d] [LiY(η5-C5Me4SiMe2NC5H4N-2-κN)2],
and [CuY(η5-C5Me4SiMe2NC5H4N-2-κN)2] [2.319(4)–
2.333(3) Å].[8] Another example of a “constrained geome-
try” complex bearing two molecules of thf is the linked
amido–fluorenyl complex [Y{(η3-3,6-tBu2Flu)SiMe2NtBu-
κN}(CH2SiMe3)(thf)2], in which an η3-coordination of the
fluorenyl fragment allows the coordination of a second
molecule of thf.[9]
A
2a
Y–C(alkyl)
C–Si(alkyl)
Y–Cpcent
Y–N
N–Cipso
N–Si
2.481(6)
1.842(6)
2.336(6)
2.327(5)
1.382(7)
1.731(5)
2.382(3)
2.382(3)
2.451(6)
1.857(7)
2.342(6)
2.312(5)
1.382(8)
1.732(5)
2.428(4)
2.419(4)
Y–O1
Y–O2
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D. Robert, P. Voth, T. P. Spaniol, J. Okuda
FULL PAPER
Scheme 2.
of the cyclopentadienyl ligand is perfectly perpendicular to solvents. NMR spectroscopic data could nonetheless be ob-
the Y–Cpcent bond in 2a (Y–Cpcent–CCp ranging from tained for complexes 5a and 5b in [D8]thf at 50 °C. The
89.22° to 90.51°), whilst Y–Cpcent–CCp angles varying from NMR investigations show that the lutetium analogues 3a–
85° to 93.16° are measured in A. The geometry of the alkyl 3c react in a similar manner with PhSiH3 to produce the
group and the Cpcent–Y–C(alkyl) angle are, however, almost corresponding hydride species.
independent of the length of the backbone (Table 1).
Reaction of 2a with HCϵCtBu (Scheme 2) afforded a 1:1
mixture of the monomeric thf adduct [Y(η5-C5Me4CH2Si-
Me2NPh-κN)(CϵCtBu)(thf)x] (4a) and the dimeric thf-free
complex [Y(η5-C5Me4CH2SiMe2NPh-κN)(CϵCtBu)]2 (7a).
The similar solubility of 4a and 7a in several solvents pre-
vented their separation. This behavior is different to that of
[Y(η5-C5Me4CH2SiMe2NCH2CH2NMe2-κN,NЈ)(CϵCt-
Bu)(thf)], which exclusively generates the dimeric base-free
complex upon recrystallization from toluene.[11]
The thf ligands in 2a are labile and can be substituted
Scheme 4.
for pyridine to produce the pyridine complex [Y(η5-C5Me4-
CH2SiMe2NPh-κN)(CH2SiMe3)(py)2] (2a-py) (Scheme 3).
The substitution is evidenced by a shift of one signal for
the C5Me4 groups to higher field (δ = 1.38 ppm in 2a-py
relative to 1.99 ppm in 2a). The pyridine complex decom-
poses overnight at room temperature by C–H activation of
the coordinated pyridine with concomitant formation of
tetramethylsilane. A red solution is obtained for which no
The dimeric structure is conserved in solution [triplets at
δ = 5.10 ppm for all three complexes 5a–5c in [D8]thf with
1JYH = 28.4 Hz (5a) and 29.9 Hz (5b and 5c)]. Crystals of
complexes 5a–5c suitable for diffraction can be grown by
layering a toluene solution of the alkyl precursors 2a–2c
with a toluene solution of PhSiH3 (5 equiv.). Structural in-
1
alkyl signals can be detected in the H NMR spectrum.
Scheme 3.
Hydrogenolysis of the Alkyl Complex
Hydrogenolysis of the alkyl complexes 2a–2c with dihy-
drogen (4 bar) was carried out in toluene (for 2a) or pen-
tane (for 2b and 2c), depending on the respective solubility
of the alkyl precursors. Stirring overnight afforded the hy-
dride complexes [Y(η5-C5Me4CH2SiMe2NC6H4R-4-κN)(µ-
H)(thf)]2 [(R = H (5a), tBu (5b), nBu (5c)] in good yields as
sparingly soluble products (Scheme 4). Whilst complexes 5a
and 5b are insoluble in aliphatic and aromatic hydrocarbons
and poorly soluble in thf, the nBu chain in the para position
Figure 3. ORTEP view of the dimeric hydride complex [Y(η5-
C5Me4CH2SiMe2NC6H4tBu-4-κN)(µ-H)(thf)]2 (5b). Thermal ellip-
soids are drawn at the 50% probability level. Only bridging hydro-
gen atoms are shown. Selected bond angles [Å] and angles [°]: Y–
O 2.367(3), Y–N 2.262(3), Y–Cpcent 2.328(3), Y···YЈ 3.6644(8);
of the phenyl ring in 5c increases its solubility in aromatic Cpcent–Y–N 103.17(11).
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Rare-Earth Metal Alkyl and Hydride Complexes
vestigations on 5b reveal a heterochiral molecule of Ci sym-
In 6a, the linked anilido–cyclopentadienyl ligand, the
metry with cyclopentadienyl rings in a trans arrangement two coordinated pyridine molecules, and the 2-hydropyridyl
(Figure 3).
ligand form a square-based pyramidal geometry around the
metal, and the structure resembles that observed in the
amido–fluorenyl complex [Y{(η3-3,6-tBu2Flu)SiMe2NtBu-
κN}(η1-NC5H6)(py)2] (Figure 4). The Y–N bond length for
the pyridine donors and the 2-hydropyridyl ligand are also
comparable. The Y–N bond length for the anilido group
and that of the amido group are of comparable length. As
in 2a, the phenyl ring is arranged parallel to the Si–N–Y
plane. The bond lengths of the anilido–cyclopentadienyl li-
gand (Y–CCp, Y–N1, N1–Cipso) are comparable with those
in 2a.
Reaction of the Hydride Complex with Pyridine
When the hydride 5a is dissolved in pyridine, a clear yel-
low solution is obtained. Partial removal of pyridine under
vacuum and cooling to –30 °C overnight afforded yellow
single crystals suitable for X-ray diffraction. The crystal-
structure analysis shows a 2-hydropyridyl complex [Y(η5-
C5Me4CH2SiMe2NPh-κN)(η1-NC5H6)(py)2] (6a) formed
by 1,2-insertion of pyridine into the Y–H bond of 5a
(Scheme 5).
Scheme 5.
The kinetically controlled 1,2-insertion product was
formed at room temperature. Isomerization to the thermo-
dynamically more stable 1,4-insertion product at higher
Figure 4. ORTEP view of the 2-hydropyridyl complex [Y(η5-
C5Me4CH2SiMe2NPh-κN)(η1-NC5H6)(py)2] (6a). Thermal ellip-
soids are drawn at the 50% probability level. Only hydrogen atoms
at the 2-hydropyridyl ligand are shown. Selected bond lengths [Å]
and angles [°]: Y–N1 2.300(5), Y–N2 2.531(5), Y–N3 2.542(5), Y–
N4 2.294(5), Y–Cring 2.604(6)–2.668(5), N1–C13 1.399(7); N1–Y–
N2 86.65(17), N1–Y–N3 84.09(17), N1–Y–N4 135.86(18), N2–Y–
N3 150.88(15), N2–Y–N4 86.03(17), N3–Y–N4 81.64(18).
1
temperatures (up to 80 °C) was not observed by H NMR
spectroscopy. In
a similar manner, the reaction of
[Y{PhC(NSiMe3)2}2(µ-H)]2 with pyridine was reported to
give the 1,2-addition product [Y{PhC(NSiMe3)2}2(η1-
NC5H6)], which also did not isomerize at higher tempera-
ture (over a day at 100 °C).[12] Isomerization to the 1,4-in-
sertion product upon heating was reported to proceed
within 2 h for the 2-hydropyridyl complex [Y(DADMB)(η1-
NC5H6)(py)2] (DADMB = 2,2-bis{(tert-butyldimethylsilyl)-
The 1,2-insertion becomes apparent in the different car-
bon–carbon bond lengths of the 2-hydropyridyl ligand. The
bonds C29–C30 and C31–C32 are longer than the other
bonds in this fragment, whilst C30–C31 and C32–C33 are
found to be much shorter (Figure 5).
amido}-6,6-dimethylbiphenyl
[{6,6Ј-Me2-(C6H3)2}(2,2Ј-
NSiMe2tBu)2]2–) obtained by 1,2-insertion of pyridine into
the Y–H bond of the hydride precursor [Y(DADMB)(µ-
H)(thf)]2.[13] Similarly, Evans et al. found that the hydride
complex [Y(η5-C5H4R)2(µ-H)(thf)]2 (R = H, Me) readily re-
acted with pyridine in polar solvents to give the 1,2-inser-
tion product, which rearranged to the 1,4-isomer.[14] Reac-
tion of the hydride complex [Y{(η3-3,6-tBu2Flu)Si-
Me2NtBu-κN}(µ-H)(thf)]2 with excess pyridine was re-
ported to directly afford the 1,4-addition product [Y{(η3-
3,6-tBu2Flu)SiMe2NtBu-κN}(η1-NC5H6)(py)2]. No evi-
dence for the existence of the 1,2-isomer was found from the
NMR spectroscopic data, possibly because of simultaneous
attack at the 2- and 4-positions of the pyridine ring, and/or
fast isomerization of the 1,2-product to the 1,4-isomer that
Figure 5. ORTEP view of the [Y(η1-NC5H6)] fragment in 6a show-
ing the discrete double bonds C30=C31 and C32=C33. Thermal
ellipsoids are drawn at the 50% probability level; bond lengths in
Å.
The results of the structure analysis were confirmed by
occurs under the experimental conditions (70 °C).[15] In the NMR spectroscopy. Five separate signals assigned to the 2-
1
Ziegler alkylation of pyridine with alkyllithium compounds, hydropyridyl ligand are observed in the H NMR spectrum
the 1,2-addition product was assumed as the intermedi- at room temperature. The two methylene protons as well as
ate.[16] Examination of the 1,2- or 1,4-insertion of pyridine the methine proton in the ortho position give rise to a doub-
was carried out with metal hydrides such as LiAlH4,[17] let each. A multiplet and a triplet are found for the protons
MgH2,[18] or ZnH2.[19]
in the meta position. A doublet of doublets is assigned to
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D. Robert, P. Voth, T. P. Spaniol, J. Okuda
FULL PAPER
Scheme 6.
the proton in the para position because of the different
3
coupling to the meta protons (3JHH = 4.0 Hz, JHH
=
6.0 Hz). The signals for the methyl groups at the cyclopen-
tadienyl ring and the methylene group of the 2-hydropyridyl
ligand undergo coalescence at 0 °C. The pyridine signals are
broad at room temperature, which suggests an exchange re-
action according to Scheme 6.
Reaction of the Hydride Complex with tert-Butylacetylene
Figure 6. ORTEP view of the dimeric alkynyl complex [Y(η5-
C5Me4CH2SiMe2NPh-κN)(µ-CϵCtBu)]2 (7a). Thermal ellipsoids
At room temperature or above, the hydride complex 5a are drawn at the 50% probability level. Hydrogen atoms are omit-
does not undergo any reaction with 1-alkenes; e.g. styrene
does not insert into the metal–hydride bond (5-fold excess).
This low reactivity may partly be due to the low solubility,
ted for clarity. Selected bond lengths [Å] and bond angles [°]: Y–N
2.1924(16), Y–C19 2.477(2), Y–C19Ј 2.483(2), Y···C20 3.061(2),
C19–C20 1.214(3), Y–Cring 2.5804(19)–2.6184(19), N–C13 1.419(2);
Y–C19–YЈ 95.80(7), C19–Y–C19 84.20(7), Y–C19–C20 156.16(17),
but we believe that the polarization of the metal–hydride
bond may be reduced and the monomer–dimer equilibrium
unfavorably affected.[20] On the other hand, protonolysis of
5a with the weak Brønsted acid HCϵCtBu forms the di-
meric alkynyl complex [Y(η5-C5Me4CH2SiMe2NPh-κN)(µ-
CϵCtBu)]2 (7a) (Scheme 7). The colorless compound is sol-
YЈ–C19–C20 106.65(15), C19–C20–C21 177.1(2).
The phenyl ring is orientated perpendicularly to the
plane defined by the Si, N, and Y atoms, which is in con-
trast to 2a and 6a. The N–C bond length in the anilido
fragment [1.419(2) Å] is longer than in the complexes 2a
and 6a [1.382(8) Å and 1.399(7) Å, respectively]. The Y–N
bond length [2.1924(16) Å] is much shorter than in 2a and
6a [2.312(5) Å and 2.300(5) Å, respectively] and is also
short relative to other amido cyclopentadienyl yttrium com-
plexes.[5a,5c,6,7,20]
The short yttrium–carbon distance and the asymmetric
coordination of the alkynyl ligand [Y–C19–C20 156.1(2)°
and YЈ–C19–C20 106.7(2)°, ∆ = 49.4°] indicate a weak π
bonding of the triple bond to the metal center (Figure 7, I).
This would also explain the fact that in the 13C{1H} NMR
spectrum, two doublets for the carbon atoms of the CϵC
bond are detected. A coupling of the bridging carbon atom
to both metal centers, as depicted in structure II, would
give rise to only one triplet.
1
uble in aromatic solvents. The H NMR spectrum at room
temperature consists of a set of signals for a molecule with
Ci symmetry with four singlets for the cyclopentadienyl
methyl groups, the SiMe2 bridge, and the tert-butyl group.
The coordination of thf was not observed. Three separate
signals (two triplets and one doublet) in a 1:2:2 ratio are
detected for the protons of the phenyl ring.
Scheme 7.
Single crystals of the alkynyl complex 7a were obtained
from a saturated benzene solution at room temperature.
Structural investigations show that the two moieties of the
structure are bridged by the alkynyl ligands, in a fashion
similar
to
that
observed
in
[Lu(η5-C5Me4Si-
Me2NC6H2Me3–2,4,6-κN)(µ-CϵCPh)]2 (Figure 6).[5b]
Figure 7. Bridging alkynyl bonding mode in 7a.
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Rare-Earth Metal Alkyl and Hydride Complexes
night. After removal of the solvent under vacuum, the residue was
extracted with pentane (3ϫ15 mL). The solvent was removed un-
der vacuum, and the remaining oil distilled under reduced pressure
(148 °C, 2 ϫ10–1 mbar) to afford 1a (1.0790 g, 73%) as a yellow
oil. 1H NMR ([D6]benzene): δ = 0.16 (s, 6 H, SiMe2), 0.96, 0.99 (d,
2JHH = 7.6 Hz, 2 H, CH2Si), 1.73, 1.75, 1.76, 1.77, 1.78, 1.87 (s, 12
H, C5Me4), 2.45, 2.55 (m, 1 H, C5Me4H), 3.11, 3.20 (br. s, 1 H,
The triple bond length is in the usual range for lantha-
nide, actinide, and transition-metal alkynyl complexes and
is comparable with that of free alkynes HCϵCR
(1.20 Å).[21] The asymmetric coordination of the alkynyl li-
gands in dimeric complexes is well known for rare-earth
metal complexes,[22] but a π interaction of the triple bond
with the metal center has so far been rarely detect-
ed.[22c,22d,23] In all other examples, the metal–β-carbon dis-
tance (Ͼ3.15 Å) is too long for such a secondary interac-
tion.
3
3
NH), 6.60 (d, JHH = 8.6 Hz, 2 H, 2-, 6-C6H5), 6.75 (t, JHH
=
5.5 Hz, 1 H, 4-C6H5), 7.12 (t, 3JHH = 6.3 Hz, 2 H, 3-, 5-C6H5) ppm.
13C{1H} NMR ([D6]benzene): δ = –1.1, –0.9, –0.7 (SiMe2), 11.3,
11.7, 11.8, 11.9, 12.6, 14.7 (C5Me4), 16.2, 16.8 (CH2Si), 51.3, 51.8
(C5Me4CH2, C attached to CH2), 116.6, 116.7, 116.8, 118.1, 118.2
(C6H5), 129.5, 129.6, 134.1, 134.5, 134.6, 138.5, 138.8 (C5Me4CH2,
C attached to Me), 147.5 (1-C6H5) ppm. EI-MS: m/z (%) = 285
(19) [M+], 192 (28) [C5Me4CH2SiMe2+], 150 (100)
[Me2SiNHC6H5+], 134 (14) [C5Me4CH2+], 120 (7) [C5Me4+], 91 (6)
[NC6H5+], 77 (2) [C6H5+], 58 (3) [SiMe2+]. C18H27NSi (285.50):
calcd. C 75.72, H 9.53, N 4.91; found C 75.76, H 9.29, N 4.85.
Conclusions
A series of yttrium and lutetium trimethylsilylmethyl
complexes bearing a CH2SiMe2-linked anilido–cyclopen-
tadienyl ligand was synthesized. The sterically small anilido
function was found to increase the Lewis acidity of the
metal center within the “constrained geometry” ligand
sphere, which generally resulted in the coordination of a
second molecule of thf in solution as well as in the solid
state. Conversion of the trimethylsilylmethyl complexes into
the hydride species resulted in the formation of dimeric
complexes of the type well studied for the tert-butylamido
congeners.[2,3,4d–4h,7,20] Reaction of pyridine with the hy-
dride complex gave the 1,2-insertion product, which did not
rearrange to the 1,4-isomer. This 1,3-H shift seems to occur
more easily when harder ancillary ligands are coordinated
to the rare-earth metal.[12] Although the reason for the se-
lective formation of the 1,2- or the 1,4-product remains ob-
scure, a more covalent Y–Namido bond may impede this re-
arrangement. Protonolysis of the hydride with tBuCϵCH
gave a donor-free dimer with alkynyl bridges in which the
metal centers are held together by weak π donation of the
carbon–carbon triple bond to the metal center.
(C5Me4H)CH2SiMe2NHC6H4tBu-4
(1b):
A
solution
of
[Li(NHC6H4tBu)] (3.967 g, 25.6 mmol) in thf (60 mL) was treated
at –78 °C with a thf solution (40 mL) of (C5Me4H)CH2SiMe2Cl
(5.850 g, 25.6 mmol). After addition, the cold bath was removed,
and the solution was warmed up to room temperature and stirred
overnight. After removal of the solvent under vacuum, the residue
was extracted with pentane (3ϫ20 mL). The solvent was removed
under vacuum, and the remaining oil distilled under reduced pres-
sure (154 °C, 2 ϫ10–1 mbar) to afford 1b (7.150 g, 82%) as a yellow
oil. 1H NMR ([D6]benzene): δ = 0.14 (s, 6 H, SiMe2), 0.92, 0.94 (d,
2JHH = 7.7 Hz, 2 H, CH2Si), 1.22 (s, 9 H, CMe3), 1.69, 1.73 (s, 12
H, C5Me4), 2.45, 2.60 (m, 1 H, C5Me4H), 3.06, 3.15 (br. s, 1 H,
3
3
NH), 6.55 (d, JHH = 8.7 Hz, 2 H, 2-, 6-C6H5), 7.12 (d, JHH
=
11.6 Hz, 2 H, 3-, 5-C6H5) ppm. 13C NMR ([D6]benzene): δ = –1,
–0.8, –0.6 (SiMe2), 11.3, 11.7, 11.8, 11.9, 12.6 (C5Me4), 14.7
(CH2Si), 31.8 (CMe3), 33.9 (CMe3), 51.3, 51.8 (C5Me4CH2, C at-
tached to CH2), 116.4 (2-,6-C6H5), 126.3 (3-, 5-C6H5), 132.8, 134.1,
134.5, 135.5, 137.1, 138.4, 138.9, 140.4, 140.5 (C5Me4CH2, C at-
tached to Me), 144.9 (1-C6H5) ppm. EI MS: m/z (%) = 341 (14)
[M+],
206
(49)
[SiMe2NHC6H4CMe3+],
192
(32)
[C5Me4CH2SiMe2+], 148 (11) [NHC6H4CMe3+], 134 (100)
[C5Me4CH2+], 133 (71) [C6H4CMe3+], 120 (7) [C5Me4+], 91 (65)
[NC6H5+], 77 (66) [C6H5+]. C22H35NSi (341.61): calcd. C 77.35, H
10.33, N 4.10; found C 78.56, H 10.48, N, 4.12.
Experimental Section
General Considerations: All operations were performed under an
inert atmosphere of argon by using standard Schlenk-line or
glovebox techniques. The solvents were purified by distillation from
sodium/triglyme benzophenone ketyl. Anhydrous rare-earth tri-
chlorides (STREM) were used as received. [Ln(CH2SiMe3)3(thf)2]
(Ln = Y, Lu)[7,24] and (C5Me4H)CH2SiMe2Cl[5a] were prepared ac-
cording to published procedures. All other chemicals were commer-
cially available and used after appropriate purification. NMR spec-
tra were recorded with a Bruker DRX 400 spectrometer (1H,
400 MHz; 13C, 101 MHz) at 25 °C, unless otherwise stated. Chemi-
cal shifts for 1H and 13C spectra were referenced internally by using
the residual solvent resonances and reported relative to tetrameth-
ylsilane. Elemental analyses were performed by the Microanalytical
Laboratory of this department. Metal titrations were carried out
in a 1  ammonium acetate buffer with edta (5ϫ10–3 ) as titrating
agent and xylenol orange as indicator.
(C5Me4H)CH2SiMe2NHC6H4nBu-4
(1c):
A
solution
of
[Li(NHC6H4nBu)] (2.328 g, 15 mmol) in thf (30 mL) was treated
at –78 °C with a thf solution (30 mL) of (C5Me4H)CH2SiMe2Cl
(3.433 g, 15 mmol). After addition, the cold bath was removed, and
the solution was warmed up to room temperature and stirred over-
night. After removal of the solvent under vacuum, the residue was
extracted with pentane (3ϫ20 mL). The solvent was removed un-
der vacuum, and the remaining oil distilled under reduced pressure
(240 °C, 2 ϫ10–1 mbar) to afford 1c (3.380 g, 66%) as a yellow oil.
1H NMR ([D6]benzene): δ = 0.19 (s, 6 H, SiMe2), 0.87 (t, JHH
=
3
2
7 Hz, 3 H, CH2CH2CH2CH3), 0.97, 1.00 (d, JHH = 7.6 Hz, 2 H,
3
CH2Si), 1.29 (sextet, JHH = 7 Hz, 2 H, CH2CH2CH2CH3), 1.61
(quintet, 3JHH = 7 Hz, 2 H, CH2CH2CH2CH3), 1.74, 1.78 (s, 12 H,
3
C5Me4), 2.50, 2.59 (m, 1 H, C5Me4H), 2.54 (t, JHH = 7 Hz, 2 H,
3
CH2CH2CH2CH3), 3.05, 3.14 (br. s, 1 H, NH), 6.58 (d, JHH
=
3
8.5 Hz, 2 H, 2-, 6-C6H5), 6.98 (d, JHH = 7.5 Hz, 2 H, 3-, 5-C6H5)
ppm. 13C{1H} NMR ([D6]benzene): δ = –1.0, –0.8, –0.6 (SiMe2),
11.3, 11.7, 11.8, 11.9, 12.6 (C5Me4), 14.2 (CH2CH2CH2CH3), 14.7
(CH2Si), 22.6 (CH2CH2CH2CH3), 34.4 (CH2CH2CH2CH3), 35.2
(CH2CH2CH2CH3), 51.3, 51.8 (C5Me4CH2, C attached to CH2),
(C5Me4H)CH2SiMe2NHPh (1a): A suspension of lithium anilide
(5.130 g, 51.8 mmol) in thf (100 mL) was treated at –78 °C with a
thf solution (70 mL) of (C5Me4H)CH2SiMe2Cl (1.1870 g,
51.8 mmol). After addition, the cold bath was removed, and the
solution was warmed up to room temperature and stirred over- 116.8 (2-, 6-C6H5), 129.4 (3-, 5-C6H5), 132.1, 132.8, 134.1, 134.5,
Eur. J. Inorg. Chem. 2008, 2810–2819
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
2815

D. Robert, P. Voth, T. P. Spaniol, J. Okuda
FULL PAPER
135.5, 137.1, 138.4, 138.9 (C5Me4CH2, C attached to Me), 145.2
C6H4), 152.2 (1-C6H4) ppm. C34H60NO2Si2Y (659.93): calcd. C
(1-C6H5) ppm. EI MS: m/z (%) = 341 (4) [M+], 206 (27) [Si- 61.88, H 9.16, N 2.12, Y 13.47; found C 61.13, H 10.36, N 2.19, Y
Me2NHC6H4(CH2)3CH3+], 192 (6) [C5Me4CH2SiMe2+], 148 (11) 13.44.
[NHC6H4(CH2]3CH3+), 134 (17) [C5Me4CH2+], 133 (71)
[Y(η5-C5Me4CH2SiMe2NC6H4nBu-4-κN)(CH2SiMe3)(thf)2] (2c): A
–78 °C cold pentane suspension (10 mL) of [Y(CH2SiMe3)3(thf)2]
[C6H4(CH2]3CH3+), 120 (54) [C5Me4+], 91 (10) [NC6H5+], 77 (23)
[C6H5+]. C22H35NSi (341.61): calcd. C 77.35, H 10.33, N 4.10;
(319 mg, 0.6 mmol) was treated with a pentane solution (8 mL) of
found C 76.77, H 10.40, N 4.38.
1c (205 mg, 0.6 mmol). After stirring for 2 h at this temperature,
the solution was warmed up to 0 °C and stirred for a further 1 h.
[Y(η5-C5Me4CH2SiMe2NPh-κN)(CH2SiMe3)(thf)2] (2a): A pen-
tane suspension (40 mL) of [Y(CH2SiMe3)3(thf)2] (1210 mg,
2.4 mmol) was treated at –78 °C with a pentane solution (20 mL)
of 1a (686 mg, 2.4 mmol). After stirring for 2 h at this temperature,
the solution was warmed up to 0 °C, whereupon a white precipitate
appeared. The solvent was filtered off, and the solid dried under
vacuum to afford 2a (1040 mg, 72%) as a white solid. Crystals suit-
able for X-ray diffraction were obtained from a saturated toluene
The volatiles were removed under vacuum to yield 2c (279 mg,
1
71%) as a pale yellow powder. H NMR ([D6]benzene): δ = –0.81
2
(d, JYH = 3.0 Hz, 2 H, YCH2), 0.31 (s, 9 H, SiMe3), 0.53 (s, 6 H,
3
SiMe2), 0.85 (t, JHH = 7.3 Hz, 3 H, CH2CH2CH2CH3), 1.18 (br.
s, 8 H, β-thf), 1.26 (sextet, 3JHH = 7.3 Hz, 2 H, CH2CH2CH2CH3),
1.52 (quintet, 3JHH = 7.3 Hz, 2 H, CH2CH2CH2CH3), 2.06 (s, 6 H,
3
C5Me4), 2.11 (s, 6 H, C5Me4), 2.25 (s, 2 H, CH2Si), 2.48 (t, JHH
1
2
solution at –40 °C. H NMR ([D6]benzene): δ = –0.91 (d, JYH
=
= 7.3 Hz, 2 H, CH2CH2CH2CH3), 3.49 (br. s, 8 H, α-thf), 6.83 (d,
3
3JHH = 8.5 Hz, 2 H, 2-, 6-C6H5), 7.06 (d, JHH = 8.3 Hz, 2 H, 3-,
2.7 Hz, 2 H, YCH2), 0.29 (s, 9 H, SiMe3), 0.51 (s, 6 H, SiMe2), 1.17
5-C6H5) ppm. 13C{1H} NMR ([D6]benzene): δ = 4.1 (SiMe2), 4.8
(SiMe3), 11.5 (C5Me4), 11.6 (C5Me4), 14.1 (CH2CH2CH2CH3),
(br. s, 8 H, β-thf), 1.99 (s, 6 H, C5Me4), 2.12 (s, 6 H, C5Me4), 2.23
3
(s, 2 H, CH2Si), 3.57 (br. s, 8 H, α-thf), 6.68 (t, JHH = 7.3 Hz, 1
3
3
1
H, 4-C6H5), 6.78 (d, JHH = 7.9 Hz, 2 H, 2-,6-C6H5), 7.20 (t, JHH
16.8 (CH2Si), 22.6 (CH2CH2CH2CH3), 25.3 (d, JYC = 43.2 Hz,
1
= 7.8 Hz, 2 H, 3-,5-C6H5) ppm. H NMR ([D8]toluene): δ = –0.97
(d, JYH = 2.76 Hz, 2 H, YCH2), 0.23 (s, 9 H, SiMe3), 0.47 (s, 6 H,
YCH2),
25.2
(β-thf),
34.5
(CH2CH2CH2CH3),
35.2
1
(CH2CH2CH2CH3), 69.8 (α-thf), 115.8 (C5Me4CH2, C attached to
Me), 116.3 (C5Me4CH2, C attached to Me), 121.3 (4-C6H4), 124.1
(C5Me4CH2, C attached to CH2), 128.6 (2-, 6-C6H4), 130.2 (3-, 5-
C6H4), 151.8 (1-C6H4) ppm. C34H60NO2Si2Y (659.93): calcd. C
61.88, H 9.16, N 2.12, Y 13.47; found C 61.62, H 9.44, N 2.42, Y
13.52.
SiMe2), 1.25 (br. s, 8 H, β-thf), 1.98 (s, 6 H, C5Me4), 2.09 (s, 6 H,
3
C5Me4), 2.18 (s, 2 H, CH2Si), 3.56 (br. s, 8 H, α-thf), 6.65 (t, JHH
3
= 7.3 Hz, 1 H, 4-C6H5), 6.73 (d, JHH = 8.1 Hz, 2 H, 2-, 6-C6H5),
3
1
7.15 (t, JHH = 7.9 Hz, 2 H, 3-, 5-C6H5) ppm. H NMR ([D8]tolu-
ene, –70 °C): δ = –0.97 (br. s, 2 H, YCH2), 0.43 (s, 9 H, SiMe3),
0.65 (s, 6 H, SiMe2), 0.96 (m, 2 H, β-thf), 1.05 (m, 2 H, β-thf), 1.89
(s, 6 H, C5Me4), 2.25 (s, 6 H, C5Me4), 2.31 (s, 2 H, CH2Si), 3.53
[Lu(η5-C5Me4CH2SiMe2NPh-κN)(CH2SiMe3)(thf)2] (3a): A pen-
tane suspension (15 mL) of [Lu(CH2SiMe3)3(thf)2] (356 mg,
0.6 mmol) was treated at –78 °C with a pentane solution (5 mL) of
1a (171 mg, 0.6 mmol). After stirring for 30 min at this tempera-
ture, the solution was warmed up to 0 °C, upon which a white
precipitate appeared. The solvent was filtered off, and the solid
dried under vacuum to afford 3a (230 mg, 56%) as a white powder.
1H NMR ([D6]benzene): δ = –0.84 (s, 2 H, LuCH2), 0.26 (s, 9 H,
SiMe3), 0.42 (s, 6 H, SiMe2), 1.17 (br. s, 8 H, β-thf), 2.06 (s, 6 H,
C5Me4), 2.12 (s, 6 H, C5Me4), 2.22 (s, 2 H, CH2Si), 3.43 (br. s, 8
3
(m, 2 H, α-thf), 3.81 (m, 4 H, α-thf), 6.53 (d, JHH = 6.7 Hz, 1 H,
3
3
2-C6H5), 6.70 (t, JHH = 7.2 Hz, 1 H, 4-C6H5), 6.84 (d, JHH
=
7.5 Hz, 1 H, 6-C6H5), 7.22 (t, 3JHH = 7.2 Hz, 1 H, 3-, 5-C6H5), 7.32
(t, JHH = 7.3 Hz, 1 H, 3-, 5-C6H5) ppm. 13C{1H} NMR ([D6]-
3
benzene): δ = 3.9 (SiMe2), 4.8 (SiMe3), 11.5 (C5Me4), 11.7 (C5Me4),
1
17.0 (CH2Si), 24.4 (d, JYC = 40.3 Hz, YCH2), 25.3 (β-thf), 70.3
(α-thf), 115.9 (C5Me4CH2, C attached to Me), 116.1 (C5Me4CH2,
C attached to Me), 116.7 (4-C6H5), 119.6 (2-,6-C6H5), 123.6
(C5Me4CH2, C attached to CH2), 130.7 (3-,5-C6H5), 156.2 (1-
C6H5) ppm. 13C{1H} NMR ([D8]toluene): δ = 4.4 (SiMe2), 5.2
3
3
H, α-thf), 6.76 (t, JHH = 7.3 Hz, 1 H, 4-C6H5), 6.93 (d, JHH
=
3
1
7.3 Hz, 2 H, 2-, 6-C6H5), 7.15 (t, JHH = 7.4 Hz, 2 H, 3-, 5-C6H5)
ppm. 13C{1H} NMR ([D6]benzene): δ = 4.2 (SiMe2), 4.8 (SiMe3),
11.4 (C5Me4), 11.5 (C5Me4), 16.3 (CH2Si), 31.3 (s, LuCH2), 25.5
(β-thf), 69.0 (α-thf), 115.3 (C5Me4CH2, C attached to Me), 115.7
(SiMe3), 12.0 (C5Me4), 12.2 (C5Me4), 17.5 (CH2Si), 24.9 (d, JYC
= 43.6 Hz, YCH2), 25.8 (β-thf), 70.7 (α-thf), 116.4 (C5Me4CH2, C
attached to Me), 116.6 (C5Me4CH2, C attached to Me), 117.2 (4-
C6H5), 120.1 (2-,6-C6H5), 124.1 (C5Me4CH2, C attached to CH2),
130.7 (3-, 5-C6H5), 156.6 (1-C6H5) ppm. C30H52NO2Si2Y (603.82):
calcd. C 59.67, H 8.68, N 2.32, Y 14.71; found C 58.78, H 8.65, N
2.87, Y 14.68.
[Y(η5-C5Me4CH2SiMe2NC6H4tBu-4-κN)(CH2SiMe3)(thf)2] (2b): A
pentane suspension (10 mL) of [Y(CH2SiMe3)3(thf)2] (527 mg,
1 mmol) was treated at –78 °C with a pentane solution (5 mL) of
1b (342 mg, 1 mmol). After stirring for 2 h at this temperature, the
solution was warmed up to 0 °C and stirred for a further 1 h. The
(C5Me4CH2,
C
attached to Me), 119.0 (4-C6H5), 122.9
(C5Me4CH2, C attached to CH2), 123.9 (2-, 6-C6H5), 129.5 (3-,5-
C6H5), 153.6 (1-C6H5) ppm. C30H52LuNO2Si2 (689.89): calcd. C
52.23, H 7.60, N 2.03, Lu 25.36; found C 49.28, H 7.60, N 3.10,
Lu 24.94.
[Lu(η5-C5Me4CH2SiMe2NC6H4tBu-4-κN)(CH2SiMe3)(thf)1.5] (3b):
A pentane suspension (10 mL) of [Lu(CH2SiMe3)3(thf)2] (349 mg,
0.6 mmol) was treated at –78 °C with a pentane solution (5 mL) of
1b (205 mg, 1 mmol). After stirring for 2 h at this temperature, the
solution was warmed to 0 °C and stirred for a further 1 h. Reducing
the volume of the solvent under vacuum resulted in the formation
volatiles were removed under vacuum to yield 2b (393 mg, 61%) as
2
a white powder. 1H NMR ([D6]benzene): δ = –0.86 (d, JYH
=
2.89 Hz, 2 H, YCH2), 0.30 (s, 9 H, SiMe3), 0.53 (s, 6 H, SiMe2),
1.17 (br. s, 8 H, β-thf), 1.27 (s, 9 H, CMe3), 2.03 (s, 6 H, C5Me4),
of a white solid that was filtered to afford, after drying, 3b (338 mg,
1
2.12 (s, 6 H, C5Me4), 2.24 (s, 2 H, CH2Si), 3.54 (br. s, 8 H, α-thf), 63%). H NMR ([D6]benzene): δ = –0.82 (s, 2 H, LuCH2), 0.25 (s,
3
3
6.79 (d, JHH = 8.5 Hz, 2 H, 2-, 6-C6H5), 7.25 (d, JHH = 8.5 Hz,
9 H, SiMe3), 0.43 (s, 6 H, SiMe2), 1.07 (br. s, 6 H, β-thf), 1.25 (s,
2 H, 3-, 5-C6H5) ppm. 13C{1H} NMR ([D6]benzene): δ = 4.1
9 H, CMe3), 2.07 (s, 6 H, C5Me4), 2.15 (s, 6 H, C5Me4), 2.23 (s, 2
3
(SiMe2), 4.5 (SiMe3), 11.5 (C5Me4), 11.6 (C5Me4), 16.9 (CH2Si),
H, CH2Si), 3.39 (br. s, 6 H, α-thf), 6.91 (d, JHH = 8.6 Hz, 2 H,
1
24.7 (d, JYC = 42.2 Hz, YCH2), 25.2 (β-thf), 31.8 (CMe3), 33.9 2-, 6-C6H5), 7.21 (d, 3JHH = 8.6 Hz, 2 H, 3-, 5-C6H5) ppm. 13C{1H}
(CMe3), 70.1 (α-thf), 115.9 (C5Me4CH2, C attached to Me), 116.1
(C5Me4CH2, attached to Me), 120.0 (4-C6H4), 123.9
NMR ([D6]benzene): δ = 4.3 (SiMe2), 4.8 (SiMe3), 11.4 (C5Me4),
11.6 (C5Me4), 16.3 (CH2Si), 25.0 (β-thf), 31.4 (LuCH2), 31.8
C
(C5Me4CH2, C attached to CH2), 126.9 (2-, 6-C6H4), 128.3 (3-, 5- (CMe3), 34.0 (CMe3), 70.5 (α-thf), 115.2 (C5Me4CH2, C attached
2816 Eur. J. Inorg. Chem. 2008, 2810–2819
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© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Rare-Earth Metal Alkyl and Hydride Complexes
to Me), 115.7 (C5Me4CH2, C attached to Me), 123.1 (C5Me4CH2, 1H NMR ([D8]thf): δ = –0.04 (br. s, 6 H, SiMe2), 1.64 (br. s, 4 H,
C attached to CH2), 124.0 (2-, 6-C6H4), 126.3 (3-, 5-C6H4), 141.7
(4-C6H4), 150.0 (1-C6H4) ppm. C32H56LuNO1.5Si2 (709.94): calcd.
C 54.14, H 7.95, N 1.97, Lu 24.64; found C 52.18, H 7.72, N 2.37,
Lu 24.88.
β-thf), 1.78 (s, 6 H, C5Me4), 1.87 (s, 2 H, CH2Si), 2.02 (s, 6 H,
C5Me4), 3.50 (br. s, 4 H, α-thf), 5.10 (t, 1JYH = 28.4 Hz, 1 H, YH),
3
6.56 (m, 3 H, 2-, 4-, 6-C6H5), 6.86 (t, JHH = 8.0 Hz, 2 H, 3-, 5-
C6H5) ppm. C44H68N2O2Si2Y2 (891.02): calcd. C 59.31, H 7.69, N
3.14, Y 19.96; found C 58.93, H 8.06, N 2.93, Y 19.22.
[Lu(η5-C5Me4CH2SiMe2NC6H4nBu-4κN)(CH2SiMe3)(thf)1.5] (3c):
A pentane suspension (10 mL) of [Lu(CH2SiMe3)3(thf)2] (349 mg,
0.6 mmol) was treated at –78 °C with a pentane solution (8 mL) of
1c (205 mg, 0.6 mmol). After stirring for 2 h at this temperature,
the solution was warmed to 0 °C and stirred for a further 1 h. The
solvent was removed under vacuum to afford 3c as a colorless oil
(290 mg, 65%). 1H NMR ([D6]benzene): δ = –0.88 (s, 2 H, LuCH2),
[Y(η5-C5Me4CH2SiMe2NC6H4tBu-4-κN)(µ-H)(thf)]2 (5b): Com-
plex 2b (486 mg, 0.75 mmol) was dissolved in pentane (8 mL) in a
thick-walled glass reactor and exposed to 4 bar of H2. After stirring
for the mixture 16 h, a white solid formed. Decanting off the super-
natant, washing the remaining solid with pentane (2ϫ5 mL), and
drying under vacuum yielded 5b (158 mg, 42%) as a white solid.
Crystals suitable for X-ray diffraction were obtained as follows:
complex 2b was dissolved in a pentane/thf mixture in a Schlenk
tube; the solution was layered with pure pentane, and a pentane
solution of phenylsilane (5 equivalents) was slowly added. Crystals
3
0.23 (s, 9 H, SiMe3), 0.40 (s, 6 H, SiMe2), 0.86 (t, JHH = 7.1 Hz,
3
3 H, CH2CH2CH2CH3), 1.09 (br. s, 6 H, β-thf), 1.25 (sextet, JHH
3
= 7.3 Hz, 2 H, CH2CH2CH2CH3), 1.49 (quintet, JHH = 7.3 Hz, 2
H, CH2CH2CH2CH3), 2.06 (s, 6 H, C5Me4), 2.13 (s, 6 H, C5Me4),
3
1
2.20 (s,
2
H, CH2Si), 2.47 (t, JHH
=
7.3 Hz,
2
H,
appeared after 3 d at 6 °C. H NMR ([D8]thf, 60 °C): δ = 0.00 (br.
CH2CH2CH2CH3), 3.38 (br. s, 6 H, α-thf), 6.86 (d, 3JHH = 8.50 Hz,
2 H, 2-, 6-C6H5), 6.99 (d, JHH = 8.30 Hz, 2 H, 3-, 5-C6H5) ppm.
s, 6 H, SiMe2), 1.26 (br. s, 9 H, CMe3), 1.73 (br. s, 4 H, β-thf), 1.77
(s, 6 H, C5Me4), 1.94 (s, 2 H, CH2Si), 2.02 (s, 6 H, C5Me4), 3.58
(br. s, 4 H, α-thf), 5.10 (t, 1JYH = 29.9 Hz, 1 H, YH), 6.58 (d, 3JHH
3
13C{1H} NMR ([D6]benzene): δ = 4.2 (SiMe2), 4.8 (SiMe3), 11.4
(C5Me4), 11.6 (C5Me4), 14.2 (CH2CH2CH2CH3), 16.3 (CH2Si),
22.6 (CH2CH2CH2CH3), 25.0 (β-thf), 31.2 (LuCH2), 34.5
(CH2CH2CH2CH3), 35.3 (CH2CH2CH2CH3), 70.9 (α-thf), 115.2
(C5Me4CH2, C attached to Me), 115.7 (C5Me4CH2, C attached to
Me), 123.0 (C5Me4CH2, C attached to CH2), 124.4 (2-, 6-C6H4),
129.4 (3-, 5-C6H4), 133.5 (4-C6H4), 150.3 (1C6H4) ppm. C32H56Lu-
NO1.5Si2 (709.94): calcd. C 54.14, H 7.95, N 1.97, Lu 24.64; found
C 51.45, H 7.72, N 2.56, Lu 24.14.
3
= 8.4 Hz, 2 H, 2-, 6-C6H4), 7.08 (d, JHH = 8.4 Hz, 2 H, 3-, 5-
C6H5) ppm. C52H84N2O2Si2Y2 (1003.23): calcd. C 62.26, H 8.44,
N 2.79, Y 17.72; found C 59.96, H 8.38, N 2.80, Y 17.12.
[Y(η5-C5Me4CH2SiMe2NC5H4nBu-4-κN)(µ-H)(thf)]2 (5c): Com-
plex 2c (396 mg, 0.6 mmol) was dissolved in pentane (10 mL) in a
thick-walled glass reactor and exposed to 4 bar of H2. After stirring
the mixture for 16 h, a white solid formed. Decanting off the super-
natant, washing the remaining solid with pentane (2ϫ5 mL), and
drying under vacuum yielded 5c (110 mg, 36%) as a white solid.
1H NMR ([D8]thf): δ = 0.02 (s, 6 H, SiMe2), 0.88 (t, 3JHH = 7.1 Hz,
[Y(η5-C5Me4CH2SiMe2NPh-κN)(CϵCtBu)(thf)x] (4a): A toluene
solution (6 mL) of 2a (95 mg, 0.157 mmol) was treated at room
temperature with tert-butylacetylene (0.1 mL, 1.2 mmol) and
stirred for 2 h at room temperature. Reducing the volume of solvent
under vacuum and cooling to –30 °C afforded a colorless crystal-
line material. In addition to the signals arising from 4a, a second
set of signals was observed, which was attributed to the donor-free
dimeric species [Y(η5-C5Me4CH2SiMe2NPh-κN)(CϵCtBu)]2 (7a).
3
3 H, CH2CH2CH2CH3), 1.32 (sextet, JHH = 7.1 Hz, 2 H,
3
CH2CH2CH2CH3), 1.53 (quintet, JHH
=
7.1 Hz,
2
H,
CH2CH2CH2CH3), 1.77 (br. s, 4 H, thf), 1.77 (s, 6 H, C5Me4), 1.93
3
(s, 2 H, CH2Si), 2.02 (s, 6 H, C5Me4), 2.46 (t, JHH = 7.1 Hz, 2 H,
1
CH2CH2CH2CH3), 3.59 (br. s, 4 H, thf), 5.11 (t, JYH = 29.9 Hz,
3
3
1 H, YH), 6.59 (d, JHH = 8.1 Hz, 2 H, 2-, 6-C6H4), 6.83 (d, JHH
= 8.1 Hz, 2 H, 3-, 5-C6H5) ppm. 13C{1H} NMR ([D8]thf): δ = 4.1
(SiMe2), 4.8 (SiMe3), 11.5 (C5Me4), 11.6 (C5Me4), 14.2
(CH2CH2CH2CH3), 16.2 (CH2Si), 22.8 (CH2CH2CH2CH3), 25.2
(β-thf), 34.6 (CH2CH2CH2CH3), 35.5 (CH2CH2CH2CH3), 72.4 (α-
thf), 115.8 (C5Me4CH2, C attached to Me), 116.3 (C5Me4CH2, C
attached to Me), 121.3 (4-C6H4), 124.1 (C5Me4CH2, C attached to
CH2), 128.6 (2-, 6-C6H4), 130.2 (3-, 5-C6H4) ppm. C52H84N2O2-
Si2Y2 (1003.23): calcd. C 62.26, H 8.44, N 2.79, Y 17.72; found C
59.92, H 8.04, N 2.81, Y 18.07.
1
Signals assigned to 4a: H NMR ([D6]benzene): δ = 0.42 (s, 6 H,
SiMe2), 1.12 (s, 9 H, CMe3), 1.29 (br. s, β-thf), 1.90 (br. s, 6 H,
C5Me4), 2.18 (br. s, 6 H, C5Me4), 2.26 (s, 2 H, CH2Si), 3.83 (br. s,
3
3
α-thf), 6.96 (t, JHH = 7.2 Hz, 1 H, 4-C6H5), 7.05 (br.d, JHH
=
3
8.4 Hz, 2 H, 2-, 6-C6H5), 7.25 (br. t, JHH = 8.0 Hz, 2 H, 3-, 5-
C6H5) ppm.
[Y(η5-C5Me4CH2SiMe2NPh-κN)(CH2SiMe3)(py)2] (2a-py): An
NMR tube was charged with 2a (20 mg, 0.033 mmol). [D6]benzene
(0.5 mL) and pyridine (0.03 mL, 0.374 mmol) were subsequently
added at room temperature, and the spectrum recorded immedi-
[Y(η5-C5Me4CH2SiMe2NPh-κN)(η1-NC5H6)(py)2] (6a): Complex
5a (116 mg, 0.130 mmol) was dissolved in pyridine (5 mL), and the
clear orange-red solution was stirred for 2 h at room temperature.
After partial removal of the solvent and cooling the solution to
–30 °C overnight, 6a (131 mg, 83%) could be obtained as yellow
1
ately. 1H NMR ([D6]benzene): δ = –0.59 (d, JYH = 2.2 Hz, 2 H,
YCH2), 0.00 (s, 9 H, SiMe3), 0.70 (s, 6 H, SiMe2), 1.38 (s, 6 H,
3
C5Me4), 2.19 (s, 2 H, CH2Si), 2.24 (s, 6 H, C5Me4), 6.52 (t, JHH
3
= 7.2 Hz, 1 H, 4-C6H5), 6.87 (d, JHH = 8.1 Hz, 2 H, 2-, 6-C6H5),
7.15 (t, 3JHH = 7.8 Hz, 2 H, 3-, 5-C6H5) ppm. 13C{1H} NMR ([D6]-
benzene): δ = 3.7 (SiMe2), 4.2 (SiMe3), 11.3 (C5Me4), 12.0 (C5Me4),
1
crystals suitable for X-ray diffraction analysis. H NMR ([D8]thf):
δ = 0.41 (s, 6 H, SiMe2), 1.75 (br. s, 6 H, C5Me4), 1.97 (s, 2 H,
1
17.2 (CH2Si), 26.4 (d, JYC = 35.3 Hz, YCH2), 115.3 (C5Me4CH2,
3
CH2Si), 2.05 (s, 6 H, C5Me4), 3.63 (d, JHH = 4.0 Hz, 2 H, 2-
C attached to Me), 115.4 (C5Me4CH2, C attached to Me), 116.3
(4-C6H5), 118.9 (2-, 6-C6H5), 123.9 (C5Me4CH2, C attached to
CH2), 130.3 (3-, 5-C6H5), 158.1 (1-C6H5) ppm.
NC5H6), 4.40 (m, 1 H, 5-NC5H6), 4.75 (m, 1 H, 3-NC5H6), 5.74
3
3
3
(dd, JHH = 4.0, JHH = 6.0 Hz, 1 H, 4-NC5H6), 6.39 (t, JHH
=
3
7.2 Hz, 1 H, 4-C6H5), 6.52 (d, JHH = 8.0 Hz, 2 H, 2-, 6-C6H5),
[Y(η5-C5Me4CH2SiMe2NPh-κN)(µ-H)(thf)]2 (5a): Complex 2a
(815 mg, 1.3 mmol) was dissolved in toluene (30 mL) in a thick-
walled glass reactor and exposed to 4 bar of H2. After stirring the
mixture for 16 h, a white solid formed. Decanting off the superna-
tant, washing the remaining solid with pentane (2ϫ5 mL), and
drying under vacuum yielded 5a (425 mg, 71%) as a white powder.
6.81 (d, JHH = 6.0 Hz, 1 H, 6-NC5H6), 6.93 (t, JHH = 7.6 Hz, 2
H, 3-, 5-C6H5), 7.28 (m, 4 H, 3-, 5-NC5H5), 7.70 (m, 2 H, 4-
NC5H5), 8.56 (m, 4 H, 2-, 6-NC5H5) ppm. 13C{1H} NMR ([D8]-
thf): δ = 4.2 (SiMe2), 11.4 (C5Me4), 11.6 (C5Me4), 17.6 (CH2Si),
48.4 (6-NC5H6), 96.1 (3-NC5H6), 99.3 (5-NC5H6), 115.9
(C5Me4CH2, C attached to Me), 116.4 (C5Me4CH2, C attached to
3
3
Eur. J. Inorg. Chem. 2008, 2810–2819
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
2817

D. Robert, P. Voth, T. P. Spaniol, J. Okuda
FULL PAPER
Table 2. Crystallographic and data collection parameters for compounds 2a, 5b, 6a, and 7a.
Compound
2a
5b
6a
7a
Empirical formula
C
649.90
30H52NO2Si2Y·0.5(C7H8) C57H96N2O2Si2Y2·C5H12 C33H41N4SiY
C48H68N2Si2Y2
907.04
Mr [gmol–1
]
1147.54
610.71
Crystal size
Crystal color and habit
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
0.30ϫ0.20ϫ0.20
Colorless block
Monoclinic
P21/n
11.018(5)
20.847(10)
15.424(7)
90
0.50ϫ0.23ϫ0.20
Colorless rod
Monoclinic
P21/c
13.226(2)
16.402(3)
15.960(2)
90
0.50ϫ0.50ϫ0.20 0.50ϫ0.40ϫ0.30
Yellow fragment
Orthorhombic
Pbca
Colorless fragment
Monoclinic
P21/n
16.74(2)
19.045(6)
19.741(15)
90
13.7548(19)
12.4306(17)
14.693(2)
90
β [°]
95.77(2)
90
3525(3)
114.184(4)
90
3158.4(8)
4/2
1.207
120(2)
90
90
6294(9)
8
1.289
243(2)
1.919
2559
111.536(3)
90
2336.8(6)
4/2
1.289
273(2)
γ [°]
V [Å3]
Z
4
Dcalcd. [gcm–3
T (K)
]
1.225
110(2)
1.750
1388
µ(Mo-Kα) [mm–1
F(000)
]
1.906
1232
2.555
952
θ Range [°]
Number of reflections collected
2.36–25.12
46746
1.69–26.07
20835
3.19–26.01
17565
1.74–27.14
29041
Number of reflections observed [I Ͼ 2σ(I)]
3177
4314
3355
4192
Number of independent reflections (Rint
Data/restraints/parameters
Goodness-of-fit on F2
)
6235 (0.3167)
6235/0/363
1.000
6246 (0.0531)
6246/21/332
1.024
6180 (0.1292)
6180/0/358
0.993
5142 (0.0732)
5142/0/253
0.959
R1, wR2 [IϾ 2σ(I)]
0.0724, 0.1366
0.1725, 0.1726
0.650 and –0.474
0.0463, 0.1127
0.0809, 0.1274
1.131 and –0.320
0.0670, 0.1377
0.1457, 0.1705
1.326 and –0.865
0.0286, 0.0722
0.0368, 0.0737
0.902 and –0.449
R1, wR2 (all data)
Largest difference in peak and hole [eÅ–3
]
2
Me), 116.8 (4-C6H5), 118.9 (2-, 6-C6H5), 124.7 (3-, 5-NC5H5), 125.1 used in the refinement by full-matrix least-squares against all Fo
(C5Me4CH2, C attached to CH2), 127.7 (4-NC5H6), 130.3 (3-, 5-
data (SHELXL-97).[28] Compounds 2a and 5b contain cocrys-
C6H5), 137.1 (4-NC5H5), 147.4 (2-NC5H6), 151.3 (2-, 6-NC5H5), tallized disordered solvent molecules in the lattice. The hydrogen
157.3 (1-C6H5) ppm. C33H39N4SiY (608.70): calcd. C 65.12, H 6.46, atoms are included in calculated positions. The position of the hy-
N 9.20, Y 14.61; found C 64.80, H 6.29, N 9.12, Y 14.27.
drogen atom of the Y2H2 core unit of 5b was localized in a Fourier
difference map and was not refined in its position. For the graphi-
cal representation, the program ORTEP-III was used as im-
plemented in the program system WINGX.[29] CCDC-679422
(2a), -679423 (5b), -679424 (6a), and -679425 (7a) contain the sup-
plementary 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.
[Y(η5-C5Me4CH2SiMe2NPh-κN)(CϵCtBu)]2 (7a): A toluene sus-
pension (15 mL) of complex 5a (150 mg, 0.168 mmol) was treated
with tert-butylacetylene (0.205 mL, 1.7 mmol) at 0 °C. After stir-
ring the mixture for 2 h, the solvent was partly removed under vac-
uum. Cooling the mixture overnight to –30 °C afforded 7a (135 mg,
1
89%) as colorless crystals suitable for X-ray diffraction. H NMR
([D6]benzene): δ = 0.57 (s, 6 H, SiMe2), 1.33 (s, 9 H, CMe3), 2.01
(s, 6 H, C5Me4), 2.29 (s, 2 H, CH2Si), 2.36 (s, 6 H, C5Me4), 6.54
3
3
(t, JHH = 7.2 Hz, 1 H, 4-C6H5), 6.60 (d, JHH = 8.4 Hz, 2 H, 2-,
Acknowledgments
6-C6H5), 7.05 (t, JHH = 8.0 Hz, 2 H, 3-, 5-C6H5) ppm. 13C{1H}
3
NMR ([D6]benzene): δ = 3.7 (SiMe2), 11.5 (C5Me4), 11.9 (C5Me4),
17.4 (CH2Si), 28.3 (CMe3), 32.8 (CMe3), 115.0 (4-C6H5), 115.9
(C5Me4CH2, C attached to Me), 116.3 (d, 2JYC = 10.7 Hz, YCϵC),
Financial support by the Deutsche Forschungsgemeinschaft and
the Fonds der Chemischen Industrie is gratefully acknowledged.
117.0 (C5Me4CH2, C attached to Me), 117.1 (2-, 6-C6H5), 123.0
1
(C5Me4CH2, C attached to CH2), 129.5 (d, JYC = 53.5 Hz, [1] a) A. L. McKnight, R. M. Waymouth, Chem. Rev. 1998, 98,
2587–2598; b) J. Okuda, T. Eberle in Metallocenes (Eds.: R. L.
Halterman, A. Togni), Wiley-VCH, Weinheim, 1998, p. 418–
457; c) H. Braunschweig, Coord. Chem. Rev. 2006, 250, 2691–
2720; d) J. Okuda, Comments Inorg. Chem. 1994, 16, 185–205;
e) U. Siemeling, Chem. Rev. 2000, 100, 1495–1526; f) H. But-
enschön, Chem. Rev. 2000, 100, 1527–1564.
YCϵC), 129.9 (3-, 5-C6H5), 157.7 (1-C6H5) ppm. C48H64N2Si2Y2
(903.03): calcd. C 63.84, H 7.14, N 3.10, Y 19.69; found C 64.01,
H 7.30, N 2.96, Y 19.43.
X-ray Crystal Structure Determination of 2a, 5b, 6a, and 7a: Rel-
evant crystallographic data for 2a, 5b, 6a, and 7a are summarized
in Table 2. The data collections were carried out on a Bruker AXS
diffractometer (for 2a, 5b, and 7a), and the program system
SMART[25] was used for the data corrections as well as for the
absorption correction. The data collection for 6a was carried out
using an Enraf NONIUS CAD4 diffractometer, and the absorption
correction was carried out using ψ-scans.[26] The structures were
solved by direct methods (SHELXS-86).[27] All non-hydrogen-
atoms were refined with anisotropic displacement parameters.
From the measured reflections, all independent reflections were
[2] a) P. J. Shapiro, E. E. Bunel, W. P. Schaefer, J. E. Bercaw, Orga-
nometallics 1990, 9, 867–869; b) W. E. Piers, P. J. Shapiro, E. E.
Bunel, J. E. Bercaw, Synlett 1990, 2, 74–84; c) P. J. Shapiro,
W. D. Cotter, W. P. Schaefer, J. A. Labinger, J. E. Bercaw, J. Am.
Chem. Soc. 1994, 116, 4623–4640.
[3] a) S. Arndt, J. Okuda, Chem. Rev. 2002, 22, 1953–1976; b) J.
Okuda, Dalton Trans. 2003, 2367–2378.
[4] For selected examples of the variation in the amido group in
group 4 metal chemistry, see: a) K. E. du Plooy, U. Moll, S.
Wocadlo, W. Massa, J. Okuda, Organometallics 1995, 14, 3129–
2818
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 2810–2819

Rare-Earth Metal Alkyl and Hydride Complexes
3131; b) F. Amor, T. P. Spaniol, J. Okuda, Organometallics
1997, 16, 4765–4767; c) F. Amor, A. Butt, K. E. du Plooy, T. P.
Spaniol, J. Okuda, Organometallics 1998, 17, 5836–5849. For
group 3 and rare-earth metal chemistry, see: d) K. C. Hultzsch,
T. P. Spaniol, J. Okuda, Organometallics 1997, 16, 4845–4856;
e) K. C. Hultzsch, T. P. Spaniol, J. Okuda, Organometallics
1998, 17, 485–488; f) S. Arndt, T. P. Spaniol, J. Okuda, Eur. J.
Inorg. Chem. 2001, 73–75; g) S. Arndt, K. Beckerle, K. C.
Hultzsch, P.-J. Sinnema, P. Voth, T. P. Spaniol, J. Okuda, J.
Mol. Catal. A 2002, 190, 215–223; h) A. T. Trifonov, T. P.
Spaniol, J. Okuda, Eur. J. Inorg. Chem. 2003, 926–935.
[5] a) A. A. Trifonov, T. P. Spaniol, J. Okuda, Organometallics
2001, 20, 4869–4874; b) M. Nishiura, Z. Hou, Y. Wakatsuki,
T. Yamaki, T. Miyamoto, J. Am. Chem. Soc. 2003, 125, 1184–
1185; c) A. A. Trifonov, T. P. Spaniol, J. Okuda, Dalton Trans.
2004, 2245–2250; d) D. Robert, A. A. Trifonov, P. Voth, J.
Okuda, J. Organomet. Chem. 2006, 691, 4393–4399.
[6] P. Voth, T. P. Spaniol, J. Okuda, Organometallics 2003, 22,
3921–3926.
[18] E. C. Ashby, A. B. Goel, J. Organomet. Chem. 1981, 204, 139–
145.
[19] A. J. de Koning, J. Boersma, G. J. M. van der Kerk, J. Or-
ganomet. Chem. 1980, 186, 159–172.
[20] a) K. C. Hultzsch, T. P. Spaniol, J. Okuda, Angew. Chem. 1999,
111, 163–165; Angew. Chem. Int. Ed. 1999, 38, 227–230; b) S.
Arndt, A. Trifonov, T. P. Spaniol, J. Okuda, M. Kitamura, T.
Takahashi, J. Organomet. Chem. 2002, 647, 158–166; c) P. Voth,
S. Arndt, T. P. Spaniol, J. Okuda, L. J. Ackerman, M. L. H.
Green, Organometallics 2003, 22, 65–76.
[21] a) Robert C. Weast (Ed.), Handbook of Chemistry and Physics,
67th ed.; CRC Press Inc., Boca Raton, Fl, 1986; Table F-158; b)
J. Dale in Chemistry of Acetylenes (Ed.: H. G. Viehe), Marcel
Dekker, New York, 1969, p. 3; Further example, HCϵCPh
1.208 Å: c) P. A. Cox, I. C. Ewart, W. M. Stigliani, J. Chem.
Soc. Faraday Trans. 2 1975, 71, 504–514.
[22] a) J. L. Atwood, W. E. Hunter, A. L. Wayda, W. J. Evans, Inorg.
Chem. 1981, 20, 4115–4119; b) W. J. Evans, I. Bloom, W. E.
Hunter, J. L. Atwood, Organometallics 1983, 2, 709–714; c) Q.
Shen, D. Zheng, L. Lin, Y. Lin, J. Organomet. Chem. 1990,
391, 307–312; d) R. Duchateau, C. T. van Wee, A. Meetsma,
J. H. Teuben, J. Am. Chem. Soc. 1993, 115, 4931–4932; e) L.
Lee, D. J. Berg, G. W. Bushnell, Organometallics 1995, 14,
5021–5023.
[23] a) J. M. Boncella, T. D. Tilley, R. A. Andersen, J. Chem. Soc.,
Chem. Commun. 1984, 710–712; b) C. M. Forsyth, G. B. Dea-
con, L. D. Field, C. Jones, P. C. Junk, D. L. Kay, A. F. Masters,
A. F. Richards, Chem. Commun. 2006, 1003–1005.
[24] a) M. F. Lappert, R. Pearce, J. Chem. Soc., Chem. Commun.
1973, 126; b) W. J. Evans, J. C. Brady, J. W. Ziller, J. Am. Chem.
Soc. 2001, 123, 7711–7712.
[7] a) K. C. Hultzsch, P. Voth, K. Beckerle, T. P. Spaniol, J. Okuda,
Organometallics 2000, 19, 228–243; b) S. Arndt, P. Voth, T. P.
Spaniol, J. Okuda, Organometallics 2000, 19, 4690–4700.
[8] M. S. Hill, P. D. Hitchcock, Angew. Chem. 2001, 113, 4213–
4216; Angew. Chem. Int. Ed. 2001, 40, 4089–4092.
[9] E. Kirillov, L. Toupet, C. W. Lehmann, A. Razavi, J.-F. Carp-
entier, Organometallics 2003, 22, 4467–4479.
[10] W.-X. Zhang, M. Nishiura, Z. Hou, Chem. Eur. J. 2007, 13,
4037–4051.
[11] P. Voth, Doctoral Thesis, RWTH Aachen University, Aachen,
Germany, 2004.
[12] R. Duchateau, C. T. van Wee, J. H. Teuben, Organometallics
1996, 15, 2291–2302.
[13] T. I. Gountchev, T. D. Tilley, Organometallics 1999, 18, 2896–
2905.
[14] W. J. Evans, J. H. Meadows, W. E. Hunter, J. L. Atwood, J. Am.
Chem. Soc. 1984, 106, 1291–1300.
[25] ASTRO, SAINT and SADABS. Data Collection and Processing
Software for the SMART System, Siemens Analytical X-ray
Instruments Inc., Madison, Wisconsin, USA, 1996.
[26] A. C. T. North, D. C. Phillips, F. S. Mathews, Acta Crystallogr.,
Sect. A 1968, 24, 351–359.
[15] E. Kirillov, C. W. Lehmann, A. Razavi, J.-F. Carpentier, Eur. J.
Inorg. Chem. 2004, 943–945.
[16] a) J. March, Advanced Organic Chemistry, Reactions, Mecha-
nisms and Structure, 3rd ed., John Wiley & Sons: New York,
1985, p. 598; b) J. A. Joule, G. F. Smith, Heterocyclic Chemistry,
Van Nostrand Reinhold Company, London, 1972, ch. 4 and
references cited therein.
[17] a) P. T. Lansbury, J. O. Petersen, J. Am. Chem. Soc. 1961, 83,
3537–3538; b) P. T. Lansbury, J. O. Petersen, J. Am. Chem. Soc.
1962, 84, 1756–1757; c) P. T. Lansbury, J. O. Petersen, J. Am.
Chem. Soc. 1963, 85, 2236–2237.
[27] G. M. Sheldrick, SHELXS-86, Program for Crystal Structure
Solution, University of Göttingen, Göttingen, Germany, 1986.
[28] G. M. Sheldrick, SHELXL-97, Program for Crystal Structure
Refinement; University of Göttingen, Göttingen, Germany,
1997.
[29] L. J. Farrugia, WinGX – Version 1.64.02, An Integrated System
of Windows Programs for the Solution, Refinement and Analysis
of Single-Crystal X-ray Diffraction Data, J. Appl. Crystallogr.
1999, 32, 837–838.
Received: March 1, 2008
Published Online: May 7, 2008
Eur. J. Inorg. Chem. 2008, 2810–2819
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
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