Synthesis and derivatization of halflanthanidocene aryl(alk)oxide complexes

Article abstract of DOI:10.1016/j.ica.2006.07.090

The reaction of halflanthanidocene aryloxides Cp^R′Ln(OAr^tBu,R)₂ (Ln = Y, La, Lu; Cp^R′ = C₅Me₅, C₄Me₄H; R = H, Me) and halflanthanidocene alkoxides [(C₅Me₅)Ln(OCH₂CMe₃)₂]₂ (Ln = Y, Lu) with trimethylaluminum (TMA) was investigated. Monomeric Cp^R′Ln(OAr^tBu,R)₂, derived from the ortho-tBu-substituted OC₆H₂tBu₂-2,6-R-4 (R = H, Me) ligands, form mono(tetramethylaluminate) complexes Cp^R′Ln(OAr^tBu,R)(AlMe₄) for the smaller lanthanide metal centers yttrium and lutetium. Such an [aryloxide] → [aluminate] ligand exchange was not observed at the larger lanthanum metal center. The mobility of the tetramethylaluminate ligands of complexes Cp^R′Ln(OAr^tBu,R)(AlMe₄) (Ln = Y, Lu) was examined by variable-temperature (VT) ¹H NMR spectroscopy, revealing two signals for bridging and terminal methyl groups at lower temperatures. The treatment of complexes Cp^R′Ln(OAr^tBu,R)(AlMe₄) with donor solvent d₈-THF gave Cp^R′Ln(OAr^tBu,R)(Me)(d₈-THF)₂ (Ln = Y, Lu) with terminal methyl groups, according to a donor-induced aluminate cleavage reaction. Dimeric [(C₅Me₅)Ln(OCH₂CMe₃)₂]₂ (Ln = Y, Lu) was synthesized from (C₅Me₅)Ln(NiPr₂)₂(THF) and reacted with two equivalents of TMA per Ln center to yield monomeric bis(TMA) adduct complexes (C₅Me₅)Ln(OCH₂CMe₃)₂(AlMe₃)₂(Ln = Y, Lu). VT NMR spectroscopic studies confirmed a high mobility of the Ln(μ-OCH₂CMe₃)(μ-Me)AlMe₂ moieties at an ambient temperature. Both bis(TMA) adduct complexes were characterized by X-ray structure analysis.

Full text of DOI:10.1016/j.ica.2006.07.090

Inorganica Chimica Acta 359 (2006) 4855–4864
www.elsevier.com/locate/ica
Synthesis and derivatization of halflanthanidocene
aryl(alk)oxide complexes
a
a
b,
*
Andreas Fischbach , Eberhardt Herdtweck , Reiner Anwander
a
Department Chemie, Lehrstuhl fu¨r Anorganische Chemie, Technische Universita¨t Mu¨nchen, Lichtenbergstraße 4, D-85747 Garching, Germany
b
Department of Chemistry, University of Bergen, Alle´gaten 41, N-5007, Bergen, Norway
Received 3 July 2006; accepted 28 July 2006
Available online 10 August 2006
Dedicated to Professor Dr. Dr. h.c. mult. Wolfgang A. Herrmann.
Abstract
0
0
The reaction of halflanthanidocene aryloxides CpR Ln(OArtBu,R)2 (Ln = Y, La, Lu; CpR = C5Me5, C4Me4H; R = H, Me) and half-
lanthanidocene alkoxides [(C5Me5)Ln(OCH2CMe3)2]2 (Ln = Y, Lu) with trimethylaluminum (TMA) was investigated. Monomeric
0
CpR Ln(OArtBu,R)2, derived from the ortho-tBu-substituted OC6H2tBu2-2,6-R-4 (R = H, Me) ligands, form mono(tetramethylalumi-
0
nate) complexes CpR Ln(OArtBu,R)(AlMe4) for the smaller lanthanide metal centers yttrium and lutetium. Such an [aryloxide] ! [alumi-
nate] ligand exchange was not observed at the larger lanthanum metal center. The mobility of the tetramethylaluminate ligands of
0
complexes CpR Ln(OArtBu,R)(AlMe4) (Ln = Y, Lu) was examined by variable-temperature (VT) 1H NMR spectroscopy, revealing
0
two signals for bridging and terminal methyl groups at lower temperatures. The treatment of complexes CpR Ln(OArtBu,R)(AlMe4) with
0
donor solvent d8-THF gave CpR Ln(OArtBu,R)(Me)(d8-THF)2 (Ln = Y, Lu) with terminal methyl groups, according to a donor-induced
aluminate cleavage reaction. Dimeric [(C5Me5)Ln(OCH2CMe3)2]2 (Ln = Y, Lu) was synthesized from (C5Me5)Ln(NiPr2)2(THF) and
reacted with two equivalents of TMA per Ln center to yield monomeric bis(TMA) adduct complexes (C5Me5)Ln(OCH2CMe3)2(AlMe3)2
(Ln = Y, Lu). VT NMR spectroscopic studies confirmed a high mobility of the Ln(l-OCH2CMe3)(l-Me)AlMe2 moieties at an ambient
temperature. Both bis(TMA) adduct complexes were characterized by X-ray structure analysis.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: Lanthanides; Alkoxides; Aryloxides; Halflanthanidocene complexes; Alkylaluminum
1. Introduction
route [10], that is, for alkali metal alkyl-based [aryl(alk)ox-
ide] ! [alkyl] transformations. Previously, several ‘‘ate’’-
free halflanthanidocene bis[aryl(alk)oxide] complexes A–F
have been structurally characterized [11–17] and revealed
secondary Lnꢀ ꢀ ꢀaryl(alk)oxide interactions in the absence
of additional donor(THF) ligands [11] (Chart 1). Com-
plexes A were successfully employed as precursors accord-
ing to the ‘‘aryl(alk)oxide’’ route for the synthesis of
complexes (C5Me5)Ln(OAr)[CH(SiMe3)2] and (C5Me5)Ln-
[CH(SiMe3)2]2 [11], while bis(TMA) adduct complex F was
obtained from the reaction of complex D (R5 = H4SiMe3)
with AlMe3 (TMA) [17].
The investigation of halfsandwich complexes is a current
topic in organorare-earth chemistry [1,2]. Particularly,
novel synthesis pathways and catalytic transformations
witness likewise on the enhanced reactivity of mono(cyclo-
pentadienyl) bis(alkyl) and bis(hydrido) derivatives [3–7].
Aryloxide and alkoxide [aryl(alk)oxide] ligands are not
only known to provide a stabilizing environment for
organolanthanide complexes [8,9] but also to act as valu-
able precursor moieties according to the ‘‘aryl(alk)oxide’’
*
We have recently reported on homoleptic rare-earth
metal complexes with exclusively O-coordinating ligands
Corresponding author. Tel.: +47 555 89491; fax: +47 555 89490.
E-mail address: reiner.anwander@kj.uib.no (R. Anwander).
0020-1693/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2006.07.090

4856
A. Fischbach et al. / Inorganica Chimica Acta 359 (2006) 4855–4864
t
Bu
O
O
Ln
Bu
t
Bu
t
Bu
Yb
Sm
O
O
O
O
t
Bu
t
Bu
t
Bu
O
t
O
t
Bu
t
Bu
t
Bu
t
Bu
t
Bu
Me
Me
A
B
C
(Ln = Y, Ce)
SiMe3
Me
R5
R5
Y
O
O
O
Y
Y
Me
Me
Ln
Ln
Al
O
O
O
Me
Me
O
O
O
O
Al
Me
D
F
E
(Ln = Y, Ce, Eu; R5 = Me5)
)
(Ln = Y; R5 = H5, H4Me, H4SiMe3
Chart 1. Halflanthanidocene bis[aryl(alk)oxide] complexes.
(carboxylate [18], aryloxide [19]) which show a distinct
reactivity toward organoaluminum compounds. Herein
we would like to describe the synthesis of heteroleptic half-
lanthanidocene bis(aryloxide) and halflanthanidocene
bis(neopentoxide) complexes and their reaction with TMA.
lization from saturated hexane or hexane/toluene mixtures
at ꢁ45 ꢁC yielded analytically pure complexes. Given the
X-ray crystallographic characterization of complexes
Cp*Ln(OArtBu,H
)
(Ln = Y, Ce) [11], monolanthanide
2
complexes are also suggested for complexes 1–3.
2. Results and discussion
2.2. Halflanthanidocene aryloxo tetramethylaluminates
2.1. Halflanthanidocene aryloxides
Alkylated mono(pentamethylcyclopentadienyl) lantha-
nide(III) aryloxide complexes of type Cp*Ce(OArtBu,H)-
[CH(SiMe3)2] were first reported in 1989 [11c]. Similarly,
the yttrium derivative was synthesized following the [aryl-
oxide] ! [alkyl] exchange reaction pathway [12]. Further-
more, dimeric methyl-bridged [Cp*Y(OArtBu,H)(l-Me)]2
was obtained from the reaction of Cp*Y(OArtBu,H)2 and
MeLi [12]. We have previously described that the
mono(tetramethylaluminate) complexes Ln(OArtBu,R)2-
(AlMe4) (Ln = Y, Lu; R = H, Me, tBu) are obtained via
[aryloxide] ! [aluminate] exchange reactions, using excess
trimethylaluminum (TMA) [19]. This organoaluminum-
mediated alkylation reaction proceeds via: (i) cleavage of
one of the Ln–O bonds, (ii) alkylation of the trivalent lan-
thanide metal center, and (iii) coordination of TMA to
Following the procedure reported previously by Teuben
and co-workers [11a] a series of mono(cyclopentadienyl)
0
complexes CpR Ln(OArtBu,R)2 (1–3) was synthesized from
homoleptic tris(aryloxides) Ln(OArtBu,R)3 and equimolar
0
amounts of sodium cyclopentadienyl compounds NaCpR
0
(CpR = C5Me5 (Cp*), C5Me4H (Cp00)) (Scheme 1). Crystal-
+ NaCp*
- NaOArt
Bu,R
Ln(OArtBu,R
)
3
Cp*Ln(OArtBu,R
)
2
toluene
110 ˚C, 24 h
1a: Ln = Y; R = H
1b: Ln = Lu; R = H
2a: Ln = Y; R = Me
2c: Ln = La; R = Me
in situ generated terminal methyl groups. Accordingly, a
0
series of new halflanthanidocene(III) complexes CpR Y-
(OArtBu,R)(AlMe4) (4–6), comprising cyclopentadienyl,
aryloxide, and tetramethylaluminate ligands, was synthe-
sized (Scheme 2). Despite the presence of a large excess
of 0TMA (4–6 equiv.) any bis(alkylated) species
CpR Ln(AlMe4)2 were not detectable by NMR spectros-
copy [4]. Furthermore, the [aryloxide] ! [aluminate]
exchange reaction was observed for the smaller lanthanide
metal centers yttrium (1a, 2a, 3) and lutetium (1b) only.
For the larger lanthanum metal center (2c), the formation
of a bis(TMA) adduct Cp*La(OArtBu,H)2(AlMe3)2 (7) was
+ NaCp''
- NaOArt
Bu,Me
Y(OArtBu,Me
)
3
Cp''Y(OArtBu,Me
)
2
toluene
110 ˚C, 24 h
3
Scheme 1. Synthesis of mono(cyclopentadienyl) lanthanide(III) aryloxide
complexes Cp*Ln(OArtBu,R (1, 2) and Cp00Y(OArtBu,Me
(3). For the
)
)
2
2
sake of completeness complex 1a is also listed; this compound has been
published previously [11b].

A. Fischbach et al. / Inorganica Chimica Acta 359 (2006) 4855–4864
4857
for these methyl groups. However, this dynamic behavior is
affected at lower temperatures. As a representative exam-
ple, the alkyl region of the proton variable-temperature
(VT) NMR spectra of complex Cp*Lu(OArtBu,H)(AlMe4)
(4b), measured in d8-toluene in the temperature range of
+50 and ꢁ80 ꢁC, is shown in Fig. 1. At Tc1 ꢂ 10 ꢁC the sig-
nal of the methyl group separated into two broadened res-
onances with an integral ratio of 12:12. Further cooling
resulted in a distinct sharpening of the lower-field-shifted
signal assignable to the bridging methyl groups Lu(l-
Me)2. Another splitting of the terminal methyl group reso-
nance appeared below Tc2 ꢂ ꢁ20 ꢁC, giving two sharp
singlets with an integral ratio of 6:6. Correspondingly, at
ꢁ80 ꢁC the 13C NMR spectrum showed three signals for
the three different carbon atoms of the tetramethylalumi-
nate ligand at d = 14.9, ꢁ7.5, and ꢁ8.1 ppm. Due to the
slightly larger metal center, the decoalescence temperatures
Tc1 and Tc2 are significantly lower for the corresponding
+ exc. AlMe3
- ½ [Me2Al( -OAr)]2
μ
Cp*Ln(OArt
)
2
Bu,R
hexane, 16 h, rt
Ln
Me
O
t
Bu
R
Me
Me
Al
Me
t`Bu
4a: Ln = Y, R = H
4b: Ln = Lu, R = H
5: Ln = Y, R = Me
+ exc. AlMe3
- ½ [Me2Al( -OAr)]2
μ
Cp''Y(OArt
)
2
Bu,Me
hexane, 16 h, rt
yttrium derivative Cp*Y(OArtBu,H)(AlMe4) (4a) (Tc1
=
ꢁ55 ꢁC, Tc2 = ꢁ75 ꢁC). As summarized in Table 1, both
Y
Me
O
substitution in the para-position of the aryloxo ligand (5)
t
Bu
Me
Me
Al
Me
t
Bu
6
Me
Scheme 2. Tetramethylaluminate formation via [aryloxide] ! [alkyl]
ligand exchange.
indicated by 1H NMR spectroscopy. The outcome of these
reactions is in good agreement with the previously reported
reactivity pattern of homoleptic tris(aryloxide) complexes
Ln(OArtBu,R)3 [19]. Complexes featuring the ‘‘larger’’ lan-
thanide metal centers lanthanum and neodymium afforded
mono(TMA) adduct complexes Ln(OArtBu,R)3(AlMe3)
(Ln = La, Nd), whereas mono(tetramethylaluminate) com-
plexes Ln(OArtBu,R)2(AlMe4) (Ln = Y, Lu) were obtained
for the ‘‘smaller’’ lanthanide metal centers yttrium and
lutetium.
Elemental analysis, FTIR and NMR spectroscopic data
were in agreement with the formation of mono(alkylated)
complexes 4–6. The proton NMR spectra of complexes
4–6 show signals of the g5-coordinated cyclopentadienyl
ligands which are only slightly shifted to a higher field com-
pared to the corresponding precursor compounds (d6-ben-
zene: Dd = 0.14–0.29 ppm). All of the yttrium complexes
(S = 1/2) display a characteristic doublet for the tetra-
methylaluminate ligand in the alkyl region of the spectra
(d6-benzene: ꢁ0.15 (4a), ꢁ0.14 (5), ꢁ0.15 ppm (6)).
Compared to the corresponding bis(aryloxide) complexes
Fig. 1. Alkyl region of the VT NMR spectra of complex Cp*Lu(OArtBu,H)-
(AlMe4) (4b) measured in d8-toluene.
Table 1
Decoalescence temperatures of the tetramethylaluminate moieties in
complexes 4–6 determined in d8-toluene
Tc1 [Ln(l-Me)2AlMe2]a
(ꢁC)
Tc2 [AlMe2]b
(ꢁC)
2
Y(OArtBu,R)2AlMe4) all of the JHY coupling constants
Cp*Y(OArtBu,H)(AlMe4) (4a)
Cp*Lu(OArtBu,H)(AlMe4) (4b)
Cp*Y(OArtBu,Me)(AlMe4) (5)
Cp00Y(OArtBu,Me)(AlMe4) (6)
a
ꢁ55
+10
ꢁ85
n.d.c
ꢁ75
ꢁ20
n.d.c
n.d.c
2
are significantly smaller (Y(OArtBu,R)2(AlMe4): JYH
ꢂ
0
3.7 Hz; CpR Y(OArtBu,R)(AlMe4): 2JYH = 2.9–3.2 Hz).
This has been interpreted as a weakening of the Ln–C(l)
bonds [20–23]. Due to the fast exchange of the terminal
and bridging methyl groups of the AlMe4 moieties at ambi-
ent temperature, all of the complexes show only one signal
Exchange between the bridging and terminal methyl groups.
Exchange between the terminal methyl groups.
Not detected.
b
c

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A. Fischbach et al. / Inorganica Chimica Acta 359 (2006) 4855–4864
and substitution of the cyclopentadienyl ligand (6) affected
2.4. Halflanthanidocene alkoxides and TMA-adducts
the decoalescence temperatures.
In contrast to the preferred [aryloxide] ! [aluminate]
ligand exchange reaction occurring for halflanthanidocene
aryloxide complexes 1a, 1b, 2, and 3, TMA adducts seem
to be the favored ‘‘alkylation’’ products in the case of lantha-
nide mono(cyclopentadienyl) bis(alkoxide) complexes. For
example, monoyttrium bis(TMA) adduct complex (C5H4Si-
Me3)Y(OCMe3)2(AlMe3)2 F was obtained from the dimeric
precursor [(C5H4SiMe3)Y(OCMe3)2]2 D by reaction with
equimolar amounts of trimethylaluminum [17]. Similarly,
homoleptic tris(TMA) adduct complexes are available for
tris(tert-butoxide) complexes Ln(OCMe3)3 [25,26] and
tris(neopentanolate) complexes [Ln(OCH2CMe3)3]4 [27,28].
A general synthesis pathway for the halflanthanidocene
complexes is based on the reaction of dimeric chloro-
bridged lanthanide di(isopropyl)amides [Ln(NiPr)2(THF)
(l-Cl)]2 [22,29] with NaCp*. Highly soluble halflanthanido-
cene bis(amide) complexes Cp*Ln(NiPr2)2(THF) are avail-
able in moderate yields after crystallization from hexane
[30]. Due to the high basicity of the (alkyl)amido ligands,
complexes Cp*Ln(NiPr2)2(THF) (Ln = Y, Lu) undergo an
efficient [amide] ! [alkoxide] ligand exchange reaction with
neopentanol HOCH2CMe3 to yield complexes [(C5H4Si-
Me3)Ln(OCH2CMe3)(l-OCH2CMe3)]2 (11) (Scheme 4).
NMR spectroscopic data of compounds 11 are in agree-
ment with the formation of dimeric complexes featuring
both bridging and terminal neopentanolate ligands [31].
Furthermore, weak IR absorption bands at 2690 (11a,
Ln = Y) and 2698 cmꢁ1 (11b, Ln = Lu) can be interpreted
as weak Lnꢀ ꢀ ꢀH–C agostic interactions originating from
the methylene group of the alkoxide ligands [32]. Similar
stretching frequencies have been reported previously for
the X-ray crystallographically evidenced homoleptic neo-
2.3. Halflanthanidocene aryloxo methyl complexes
Heteroleptic halflanthanidocene aryloxo complexes
0
CpR Ln(OArtBu,R)(Me)(d8-THF)2 (Ln = Y, Lu; 8–10) with
terminal methyl groups were synthesized via THF-donor-
induced cleavage of the corresponding tetramethylalumi-
nate derivatives. Such ‘‘Ln–Me’’ species were identified in
NMR-scale reactions in the presence of excess d8-THF
(Scheme 3; by-product: Me3Al(d8-THF)). The donor (d8-
THF) molecules coordinate to the sterically unsaturated
lanthanide metal centers and, thus, prevent the formation
0
of methyl-bridged dimers [CpR Ln(OArtBu,R)(l-Me)]2
[15,24]. The proton and carbon NMR spectroscopies of
complexes 8–10 revealed the appearance of new Ln–Me
resonances in the range of ꢁ0.41 to ꢁ0.67 ppm (1H), and
from 18.3 to 27.6 ppm (13C), respectively. Due to JHY
2
1
and JCY coupling, doublets were observed for all of the
yttrium complexes. Chemical shifts and coupling constants
are in good agreement with the values obtained for similar
bis(aryloxide) and bis(cyclopentadienyl) complexes (see
Table 2).
R'
+ exc.
d8-THF
- Me3Al(
d
8-THF)
Ln
Bu
Me
O
t
Bu
R
C6D6
10 min, rt
Me
Me
Al
Me
t
R'
pentoxides [Ln(OCH2CMe3)3]4 of lanthanum (2688 cmꢁ1
and neodymium (2692 cmꢁ1) [33].
)
d
8-THF
Ln
Bu
O
t
Bu
R
d
8-THF
+ 2 HOCH2CMe3
Me
t
8a: Ln = Y; R = H, R' = Me
8b: Ln = Lu; R = H, R' = Me
9: Ln = Y; R = Me, R' = Me
10: Ln = Y; R = Me, R' = H
Cp*Ln(NiPr2)2(THF)
½ [Cp*Ln(OCH2CMe3)2]2
hexane, 2 h, rt
- 2 HN Pr2
- THF
i
11a: Ln = Y
11b: Ln = Lu
Scheme 3. Donor-induced aluminate cleavage. Formation of halflanthan-
idocene aryloxo methyl complexes 8–10.
Scheme 4. Synthesis of halflanthanidocene alkoxide complexes 11a
(Ln = Y) and 11b (Ln = Lu) via amine elimination.
Table 2
Summary of NMR spectroscopic dataa of the terminal methyl groups in complexes 8–10
Complex
dH(Me) (ppm)
2JHY(Me) (Hz)
dC(Me) (ppm)
1JCY(Me) (Hz)
Cp*(ArtBu,HO)YMe(d8-THF)2 (8a)
Cp*(ArtBu,HO)LuMe(d8-THF)2 (8b)
Cp*(ArtBu,MeO)YMe(d8-THF)2 (9)
Cp00(ArtBu,MeO)YMe(d8-THF)2 (10)
(ArtBu,HO)2YMe(d8-THF)2 [25]
Cpꢃ2YMeðTHFÞ [26]
ꢁ0.52
ꢁ0.41
ꢁ0.53
ꢁ0.67
0.12
2.2
21.9
27.6
21.3
18.3
27.4
21.4
n.d.b
58.1
2.2
2.4
2.9
2.3
2.0
58.4
56.1
64.9
56.2
n.d.b
ꢁ0.66
Me2Si(C5Me4)2YMe(THF) [23]
a
ꢁ0.80
Spectra measured in d6-benzene at ambient temperature.
b
Signal not detected.

A. Fischbach et al. / Inorganica Chimica Acta 359 (2006) 4855–4864
4859
Bis(TMA) adduct complexes Cp*Ln(OCH2CMe3)2-
(AlMe3)2 (12) were obtained within 1 h upon addition of
four equivalents of trimethylaluminum to hexane mixtures
of the dimeric halflanthanidocene alkoxides 11. Recrystal-
lization from saturated hexane solutions at ꢁ45 ꢁC gave
colorless crystals in good yields (12a: 77%, 12b: 83%). Ele-
mental analysis and NMR and IR data are in agreement
with the molecular composition shown in Scheme 5. In
addition to the signals of the Cp* and neopentanolate
ligands, proton and carbon NMR spectra revealed typical
alkylaluminum peaks. Due to a rapid exchange of bridging
and terminal methyl groups at an ambient temperature
only one slightly broadened resonance of the coordinated
TMA molecules was observed for the yttrium derivative
12a (d = ꢁ0.30 ppm, 18H). In contrast, a distinct separa-
tion of this signal with the expected integral ratio of 6:12
for two bridging (dl = 0.20 ppm) and four terminal methyl
groups (dt = ꢁ0.37 ppm) was observed for complex 12b
featuring the slightly smaller lutetium metal center.
Fig. 3. Selected bond lengths and angles of both com-
pounds are summarized in Table 3.
Similar to the previously published tert-butoxide complex
(C5H4SiMe3)Y(OCMe3)2(AlMe3)2 (F) [17] the lanthanide
VT NMR experiments finally confirmed the tempera-
ture-depended mobility of the coordinated trimethylalumi-
num molecules for both yttrium and lutetium metal
centers. The alkyl region of the VT NMR spectra of com-
plex Cp*Y(OCH2CMe3)2(AlMe3)2 (12a) in d8-toluene is
shown in Fig. 2. The appearance of two separated signals
for bridging and terminal TMA methyl groups was
observed below 5 ꢁC. An additional separation of the ter-
minal methyl groups occurred below ꢁ35 ꢁC. Integral
ratios and a 2JHY coupling constant of 5.2 Hz for the bridg-
ing methyl groups, which is only observable below ꢁ30 ꢁC,
are in agreement with the signal assignment shown in
Fig. 2.
Fig. 2. Alkyl region of the VT NMR spectra of complex Cp*Y(OCH2C-
Me3)2(AlMe3)2 (12a) measured in d8-toluene.
Single crystals of complexes 12a and 12b suitable for an
X-ray structure determination were obtained from satu-
rated hexane solutions at ꢁ45 ꢁC. Complexes 12a and
12b crystallize isostructurally in the orthorhombic space
group P212121 with four molecules in the unit cell. The
solid state structure of the lutetium derivative is shown in
O
+ 4 AlMe3
O
Ln
Ln
O
hexane
1 h, rt
O
Ln
Me
O
2
Me
Me
Al
O
Me
Al
Me
Me
12a: Ln = Y
12b: Ln = Lu
Fig. 3. ORTEP style representation of the molecular structure of
Cp*Lu(OCH2CMe3)2(AlMe3)2 (12b) in the solid state. Atomic displace-
ment parameters are drawn at the 50% probability level. Hydrogen atoms
are omitted for clarity.
Scheme 5. Adduct formation at halflanthanidocene bis(neopentoxide)
complexes.

4860
A. Fischbach et al. / Inorganica Chimica Acta 359 (2006) 4855–4864
Table 3
complexes with Ln(l-OR)(l-Me)AlMe2 (adduct com-
plexes) and Ln(l-Me)2AlMe2 moieties were obtained. Var-
iable-temperature (VT) 1H NMR spectroscopy clearly
indicated a hindered mobility of the methyl ligands at
lower temperatures. Moreover, halflanthanidocene amide
complexes (C5Me5)Ln(NiPr2)2(THF) (Ln = Y, Lu) were
found as efficient precursors for donor-‘‘free’’ halflanthan-
idocene bis(alkoxide) complexes, according to an amine
elimination reaction.
It is well established that the degree of alkylation is cru-
cial for the catalytic performance of rare-earth metal cen-
ters in Ziegler–Natta-type olefin transformation reactions
[18,28]. The present study is supposed to contribute to a
better understanding of the ancillary ligand effects (here
cyclopentadienyl ligands) during catalyst activation
(=alkylation).
Selected bond lengths and bond angles of complexes Cp*Y(OCH2C-
Me3)2(AlMe3)2 (12a) and Cp*Lu(OCH2CMe3)2(AlMe3)2 (12b)
Compound
12a
12b
a
˚
Bond lengths (A)
Lnꢀ ꢀ ꢀAl1
Lnꢀ ꢀ ꢀAl2
Ln–O1
Ln–O2
Ln–C1
Ln–C4
Al1–O1
Al2–O2
Al1–C1
3.166(1)
3.176(1)
2.243(2)
2.260(2)
2.585(3)
2.577(4)
1.838(2)
1.846(2)
2.053(4)
2.043(4)
2.620(3)–2.671(4)
2.351
3.119(1)
3.123(1)
2.197(2)
2.216(2)
2.540(4)
2.536(4)
1.835(2)
1.844(3)
2.056(4)
2.046(4)
2.581(4)–2.629(4)
2.303
Al2–C4
Lnꢀ ꢀ ꢀCp(region)
Lnꢀ ꢀ ꢀCg
Bond angles (ꢁ)a
Cgꢀ ꢀ ꢀLnꢀ ꢀ ꢀAl1
Cgꢀ ꢀ ꢀLnꢀ ꢀ ꢀAl2
Al1ꢀ ꢀ ꢀLnꢀ ꢀ ꢀAl2
Ln–O1–Al1
Ln–O2–Al2
Ln–C1–Al1
Ln–C4–Al2
O1–Ln–O2
O1–Ln–C1
O1–Ln–C4
O2–Ln–C4
a
118.35
124.44
117.18
118.92
124.88
116.18
4. Experimental
101.29(9)
100.84(8)
85.3(1)
86.0(1)
123.40(7)
74.9(1)
88.2(1)
74.7(1)
101.0(1)
100.2(1)
84.8(2)
85.2(2)
122.54(9)
76.3(1)
86.5(1)
76.2(1)
4.1. Methods and materials
All operations were performed with a rigorous exclusion
of air and water, using high-vacuum and glovebox tech-
niques (MB Braun MB150B-G-II; <1 ppm O2, <1 ppm
H2O). The solvents were predried and distilled from Na/
K alloy (benzophenone ketyl) under argon. Deuterated sol-
vents were obtained from Deutero GmbH, degassed and
dried over Na/K alloy. Trimethylaluminum was obtained
Cg denotes the centroid of the Cp ligand.
metal center is formally seven coordinated, by one g5-coor-
dinated Cp* ligand, two neopentoxide oxygen atoms and
two carbon atoms of the two bridging methyl groups.
For the yttrium derivative 12a, the Y–O (2.243(2) and
2.260(2) A) and the Y–C(l) (2.577(2) and 2.585(3) A) bond
distances are in agreement with structurally related com-
from Strem Chemicals and used as received. Ln(OArtBu,R
)
3
[34] and (C5Me5)Y(OArtBu,H
)
[11a] were synthesized
2
according to the literature procedures. NMR spectra were
1
recorded either on a JEOL-GX-400 (FT, 399.78 MHz H;
100.5 MHz 13C) or on a JEOL JNM-GX-270 (FT,
˚
˚
1
270.16 MHz H; 67.93 MHz 13C) spectrometer in d6-ben-
1
zene at 25 ꢁC unless otherwise noted. H and 13C shifts
plexes such as formally seven coordinated
F (av.
˚
˚
2.280(4) A and av. 2.577(7) A, respectively) [17] and five
are referenced to internal solvent resonances and reported
relative to TMS. IR spectra were recorded on a Perkin–
Elmer 1650-FTIR spectrometer as nujol mulls. Elemental
analyses were performed in the microanalytical laboratory
of the institute.
coordinated Y(OArtBu,H)3(AlMe3)2 (av. 2.230(1) A and
˚
˚
av. 2.542(2) A, respectively) [19]. Due to the slightly smaller
rare-earth metal center, all of the bond lengths of the lute-
tium derivative 12b are slightly shorter (Lu–O, 2.197(2) and
˚
˚
2.216(2) A; Lu–C(l), 2.540(4) and 2.533(4) A). Both com-
plexes show an asymmetrical coordination of the [(l-
Me)(l-OCH2CMe3)AlMe2] moieties, which is reflected in
two different Cg–Ln–Al angles between the aluminum
atoms of the coordinated TMA molecules and the center
of the Cp* ligand (12a: D(Cg–Y–Al) = 6.10ꢁ, 12b: D(Cg–
Lu–Al) = 5.96ꢁ). These differences can be attributed to
packing effects within the crystal lattices.
4.2. Synthesis
4.2.1. General procedure for the synthesis of
halflanthanidocene aryloxides 1–3
In a round-bottom flask attached with a reflux conden-
sor 1.0 mmol of the homoleptic lanthanide metal aryloxide
Ln(OArtBu,R)3 was dissolved in 30 mL of toluene, and 1.0
equiv. of the sodium cyclopentadienyl compound was
added under stirring. The mixture was heated to reflux
for 24 h. Then, the solvent was removed in vacuo. The
remaining solid was extracted into hexane and crystallized
from hexane or hexane/toluene mixtures at ꢁ45 ꢁC to give
complexes 1–3 in good yields.
3. Summary remarks
Halflanthanid0ocene aryloxide and neopentoxide
complexes CpR Ln(OArtBu,R
)
and [(C5Me5)Ln(OCH2-
2
CMe3)2]2, respectively, reveal a distinct reaction behavior
with trimethylaluminum (TMA). Depending on the size
of the rare-earth metal center and the stereoelectronic
features of the aryl(alk)oxide ligands, heterobimetallic
4.2.1.1. Synthesis of (C5Me5)Lu(OArtBu,H)2 (1b). Follow-
ing the procedure described above, Lu(OArtBu,H)3 (0.794 g,

A. Fischbach et al. / Inorganica Chimica Acta 359 (2006) 4855–4864
4861
1.00 mmol) and NaC5Me5 (0.158 g, 1.00 mmol) yielded 1b as
colorless crystals (0.559 g, 0.78 mmol, 78%). IR (nujol):
m = 1581 w, 1413 s, 1249 s, 1099 w, 877 m, 865 m, 745 m,
4.2.2.1. Synthesis of (C5Me5)Y(OArtBu,H)(AlMe4) (4a).
Following the procedure described above, 1a (0.222 g,
0.35 mmol) and TMA (0.101 g, 1.40 mmol) yielded 4a as
a colorless solid (0.091 g, 0.18 mmol, 51%). IR (nujol):
m = 1582 w, 1410 m, 1303 w, 1245 s, 1210 w, 1193 w,
1169 w, 1153 w, 1127 w, 1102 w, 1021 w, 871 m, 748 m,
1
3
722 m, 663 s cmꢁ1. H NMR: d = 7.27 (d, JHH = 7.7 Hz,
3
4H, Ar-Hmeta), 6.84 (t, JHH = 7.7 Hz, 2H, Ar-Hpara), 1.85
(s, 15H, C5Me5), 1.54 (s, 36H, CMe3). 13C{1H} NMR:
d = 161.2 (Cipso), 136.6, 125.6, 120.7, 117.5 (C5Me5), 35.3
(CMe3), 32.4 (CMe3), 11.6 (C5Me5). Anal. Calc. for
C38H57LuO2: C, 63.32; H, 7.97. Found: C, 63.81; H, 8.14%.
1
697 m, 663 m, 582 w, 459 w cmꢁ1. H NMR: d = 7.25 (d,
3
3JHH = 7.7 Hz, 2H, Ar-Hmeta), 6.85 (t, JHH = 7.7 Hz,
1H, Ar-Hpara), 1.80 (s, 15H, C5Me5), 1.36 (s, 18H,
2
CMe3), ꢁ0.15 (d, JYH = 2.9 Hz, 12H, AlMe4). 13C{1H}
4.2.1.2. Synthesis of (C5Me5)Y(OArtBu,Me)2 (2a). Follow-
ing the procedure described above, Y(OArtBu,Me)3 (0.896 g,
1.20 mmol) and NaC5Me5 (0.189 g, 1.20 mmol) yielded 2a
NMR: d = 161.1 (d, JCY = 5.4 Hz, Cipso), 137.4, 125.2,
2
121.8, 118.2 (C5Me5), 34.9 (CMe3), 31.7 (CMe3), 11.5
(C5Me5), 1.4 (br, AlMe4). Anal. Calc. for C28H48AlOY:
C, 65.10; H, 9.37. Found: C, 65.50; H, 9.52%.
1
as colorless crystals (0.543 g, 0.82 mmol, 68%). H NMR:
d = 7.12 (s, 4H, Ar-Hmeta), 2.33 (s, 6H, Ar-Me), 1.88 (s,
15H, C5Me5), 1.53 (s, 36H, CMe3). 13C{1H} NMR:
4.2.2.2. Synthesis of (C5Me5)Lu(OArtBu,H)(AlMe4) (4b).
Following the procedure described above, 1b (0.419 g,
0.58 mmol) and TMA (0.200 g, 2.77 mmol) yielded 4b as
a colorless solid (0.233 g, 0.39 mmol, 67%). IR (nujol):
m = 1582 w, 1410 s, 1246 s, 1193 m, 1102 w, 1023 w, 874
2
d = 158.5 (d, JCY = 4.2 Hz, Cipso), 136.2, 126.1, 125.2,
121.2 (C5Me5), 35.2 (CMe3), 32.5 (CMe3), 21.5 (Ar-Me),
11.6 (C5Me5). Anal. Calc. for C40H61O2Y: C, 72.48; H,
9.28. Found: C, 72.31; H, 9.16%.
m, 824 w, 748 s, 720 s, 700 m, 662 m, 585 m, 471 w
3
4.2.1.3. Synthesis of (C5Me5)La(OArtBu,Me
)
(2c). Fol-
cmꢁ1
.
1H NMR: d = 7.28 (d, JHH = 7.7 Hz, 2H, Ar-
2
3
lowing the procedure described above, La(OArtBu,Me
)
3
H
meta), 6.86 (t, JHH = 7.7 Hz, 1H, Ar-Hpara), 1.82 (s,
(1.275 g, 1.60 mmol) and NaC5Me5 (0.252 g, 1.60 mmol)
yielded 2c as a colorless solid (0.324 g, 0.46 mmol, 28%).
IR (nujol): m = 1417 s, 1239 s, 1212 m, 1118 w, 1022 w,
888 w, 860 m, 824 m, 804 w, 794 w, 778 w, 723 w, 524
15H, C5Me5), 1.37 (s, 18H, CMe3), 0.04 (s, br, 12H,
AlMe4). 13C{1H} NMR: d = 162.0 (Cipso), 137.6, 125.1,
120.7, 118.3 (C5Me5), 35.0 (CMe3), 31.7 (CMe3), 11.5
(C5Me5); AlMe4 not detected. Anal. Calc. for C28H48Al-
LuO: C, 55.81; H, 8.03. Found: C, 55.90; H, 8.12%.
m, 493 w cmꢁ1 1H NMR: d = 7.10 (s, 4H, Ar-Hmeta),
.
2.30 (s, 6H, Ar-Me), 1.96 (s, 15H, C5Me5), 1.49 (s, 36H,
CMe3). 13C{1H} NMR: d = 159.3 (Cipso), 136.6, 125.9,
125.0, 123.2 (C5Me5), 34.7 (CMe3), 32.0 (CMe3), 21.5
(Ar-Me), 11.2 (C5Me5). Anal. Calc. for C40H61LaO2: C,
67.40; H, 8.63. Found: C, 66.99; H, 8.10%.
4.2.2.3. Synthesis of (C5Me5)Y(OArtBu,Me)(AlMe4) (5).
Following the procedure described above, 2a (0.265 g,
0.40 mmol) and TMA (0.173 g, 2.40 mmol) yielded 5 as
colorless crystals (0.108 g, 0.20 mmol, 51%). IR (nujol):
m = 1422 m, 1350 m, 1295 w, 1257 m, 1242 s, 1214 m,
1188 m, 1121 m, 1023 w, 950 w, 893 w, 860 m, 840 s, 809
4.2.1.4. Synthesis of (C5Me4H)Y(OArtBu,Me)2 (3). Follow-
ing the procedure described above, Y(OArtBu,Me)3 (0.710 g,
0.95 mmol) and NaC5Me4H (0.137 g, 0.95 mmol) yielded 3
as colorless crystals (0.378 g, 0.58 mmol, 61%). IR (nujol):
m = 1422 s, 1253 s, br, 1215 w, 1120 w, 1021 w, 860 m, 835
1
w, 779 w, 694 s, 578 m, 542 m cmꢁ1. H NMR: d = 7.10
(s, 2H, Ar-H), 2.31 (s, 3H, Me), 1.82 (s, 15H, C5Me5),
2
1.38 (s, 18H, CMe3), ꢁ0.14 (d, JHY = 3.2 Hz, 12H,
2
AlMe4). 13C{1H} NMR: d = 158.9 (d, JCY = 5.4 Hz,
1
s, 807 m, 790 w, 777 m, 722 m, 540 s cmꢁ1. H NMR:
Cipso), 136.9, 125.9, 125.5, 121.5 (C5Me5), 34.6 (CMe3),
d = 7.13 (s, 4H, Ar-Hmeta), 5.94 (s, 1H, C5Me4H), 2.33 (s,
6H, Ar-Me), 1.95 (s, 6H, C5Me4H), 1.86 (s, 6H, C5Me4H),
1.53 (s, 36H, CMe3). 13C{1H} NMR: d = 158.8 (d,
2JCY = 4.2 Hz, Cipso), 136.4, 126.0, 125.2, 122.5 (C5Me4H),
114.4 (C5Me4H), 35.0 (CMe3), 32.4 (CMe3), 21.5 (Ar-Me),
13.3 (C5Me4H), 11.4 (C5Me4H). Anal. Calc. for
C39H59O2Y: C, 72.20; H, 9.17. Found: C, 72.14; H, 9.07%.
31.5 (CMe3), 21.2 (Me), 11.5 (C5Me5), 1.2 (br, AlMe4).
Anal. Calc. for C29H50AlOY: C, 65.65; H, 9.50. Found:
C, 65.25; H, 9.32%.
4.2.2.4. Synthesis of (C5Me4H)Y(OArtBu,Me)(AlMe4) (6).
Following the procedure described above, 3 (0.227 g,
0.35 mmol) and TMA (0.151 g, 2.10 mmol) yielded 6 as a
colorless solid (0.127 g, 0.25 mmol, 70%). IR (nujol):
m = 1422 s, 1352 m, sh, 1256 s, 1246 s, 1210 m, 1191 m,
1120 w, 1022 w, 888 w, 862 w, 842 s, 808 w, 788 m, 777
4.2.2. General procedure for the synthesis of
halflanthanidocene aryloxo tetramethylaluminates 4–6
0
In a glovebox, halflanthanidocene aryloxide CpR Ln-
(OArtBu,R)2 was dissolved in a small amount of hexane and
a hexane solution of 4–6 equiv. of TMA was added slowly
at ambient temperature. The mixture was stirred for 16 h.
Then, the solvent and excess ofTMA were removed in vacuo.
The remaining solid was dissolved in hexane and crystallized
at ꢁ45 ꢁC to give complexes 4–6 in moderate yields.
m, 719 s, 693 m, 586 m, 542 m cmꢁ1. H NMR: d = 7.11
1
(s, 2H, Ar-Hmeta), 5.65 (s, 1H, C5Me4H), 2.31 (s, 3H, Ar-
Me), 1.91 (s, 6H, C5Me4H), 1.80 (s, 6H, C5Me4H), 1.38
2
(s, 18H, CMe3), ꢁ0.15 (d, JHY = 2.9 Hz, 12H, AlMe4).
2
13C{1H} NMR: d = 159.0 (d, JCY = 5.4 Hz, Cipso), 137.1,
126.2, 125.8, 123.2 (C5Me4H), 122.7 (C5Me4H), 113.9
(C5Me4H), 34.8 (CMe3), 31.7 (CMe3), 21.4 (Me), 13.2

4862
A. Fischbach et al. / Inorganica Chimica Acta 359 (2006) 4855–4864
(C5Me4H), 11.4 (C5Me4H), 1.3 (br, AlMe4). Anal. Calc. for
C28H48AlOY: C, 65.10; H, 9.37. Found: C, 65.20; H,
9.42%.
(C5Me4H), 117.7 (C5Me4H), 109.8 (C5Me4H), 35.6
(CMe3), 31.5 (CMe3), 21.4 (Me), 18.3 (d, JCY = 56.1 Hz,
Y–Me), 13.0 (C5Me4H), 12.2 (C5Me4H).
1
4.2.2.5. Synthesis of (C5Me5)La(OArtBu,Me)2(AlMe3)2
(7). Following the procedure described above, 2c
(0.178 g, 0.25 mmol) and TMA (0.072 g, 1.00 mmol)
yielded 245 mg of a sticky white solid. Crude product
(ꢄ95%): 1H NMR: d = 7.06 (s, 4H, Ar-Hmeta), 2.23 (s,
6H, Me), 1.85 (s, 15H, C5Me5), 1.46 (s, 36H, CMe3),
ꢁ0.27 (s, br, 18H, AlMe3). 13C{1H} NMR: d = 160.0
(Cipso), 138.5, 126.2, 124.4, 122.1 (C5Me5), 34.9 (CMe3),
32.5 (CMe3), 21.3 (Me), 11.1 (C5Me5), 2.0 (br, AlMe3).
4.2.4. Synthesis of [(C5Me5)Y(OCH2CMe3)-
(l-OCH2CMe3)]2 (11a)
In a glovebox, 0.427 g (0.86 mmol) of (C5Me5)Y-
(NiPr2)2(THF) were dissolved in 10 mL of hexane, and a
solution of 0.152 g (1.72 mmol) of neopentanol in a small
amount of hexane was added under stirring. The mixture
was stirred at ambient temperature for 3 h. Then, all vola-
tiles were removed in vacuo. The residue was washed with a
small amount of cold hexane and dried under vacuum to
give 0.286 g (0.36 mmol, 84%) of 11a as a colorless solid.
IR (nujol): m = 2690 w, 1305 w, 1129 s, 1047 m, 1016 m,
4.2.3. General procedure for the NMR-scale synthesis of
halflanthanidocene aryloxo methyl complexes 8–10
In an NMR tube an amount of 15–20 mg of the appro-
1
933 w, 614 m, 558 w cmꢁ1. H NMR: d = 3.70 (s, 4H,
CH2), 3.48 (s, 4H, l-CH2), 2.14 (s, 30H, C5Me5), 1.00 (s,
18H, l-CMe3), 0.90 (s, 18H, CMe3). 13C{1H} NMR:
d = 117.6 (C5Me5), 78.4 (CH2), 76.5 (CH2), 33.6 (CMe3),
33.1 (CMe3), 27.0 (CMe3), 26.5 (CMe3), 11.3 (C5Me5).
Anal. Calc. for C40H74O4Y2: C, 60.29; H, 9.36. Found: C,
60.55; H, 9.60%.
priate halflanthanidocene aryloxo tetramethylaluminate
0
CpR Ln(OArtBu,R)(AlMe4) was dissolved in 0.5 mL of d6-
benzene and 3–5 drops of d8-THF were added. The
NMR tube was sealed and the quantitative donor-induced
1
aluminate cleavage was examined by H and 13C NMR
spectroscopy. The quantitative formation of the byproduct
(cleavage product) Me3Al Æ THF was observed in all of the
experiments.
4.2.5. Synthesis of [(C5Me5)Lu(OCH2CMe3)-
(l-OCH2CMe3)]2 (11b)
4.2.3.1. NMR data of (C5Me5)Y(OArtBu,H)(Me)(d8-
Following the procedure of 11a, 0.389 g (0.67 mmol) of
(C5Me5)Lu(NiPr2)2(THF) and 0.118 g (1.34 mmol) of neo-
pentanol gave 0.286 g (0.30 mmol, 88%) of 11b as a color-
less solid. IR (nujol): m = 2698 w, 1304 w, 1257 w, 1134 s,
1
3
THF)2 (8a). H NMR: d = 7.36 (d, JHH = 7.7 Hz, 2H,
3
Ar-Hmeta), 6.75 (t, JHH = 7.7 Hz, 1H, Ar-Hpara), 2.05 (s,
15H, C5Me5), 1.55 (s, 18H, CMe3), ꢁ0.52 (d,
2JHY = 2.2 Hz, 3H, Y–Me). 13C{1H} NMR: d = 163.7
(Cipso), 138.0, 125.4, 117.4, 116.0 (C5Me5), 35.4 (CMe3),
1042 s, 1014 s, 933 w, 898 w, 616 m, 560 m cmꢁ1. H
1
NMR: d = 3.74 (s, 4H, CH2), 3.55 (s, 4H, l-CH2), 2.14
(s, 30H, C5Me5), 1.01 (s, 18H, l-CMe3), 0.91 (s, 18H,
CMe3). 13C{1H} NMR: d = 117.4 (C5Me5), 79.1 (CH2),
77.3 (CH2), 33.8 (CMe3), 32.9 (CMe3), 27.1 (CMe3), 26.5
(CMe3), 11.5 (C5Me5). Anal. Calc. for C40H74Lu2O4: C,
49.58; H, 7.70. Found: C, 50.10; H, 8.08%.
1
31.5 (CMe3), 21.9 (d, JCY = 58.1 Hz, Y–Me), 11.9
(C5Me5).
4.2.3.2. NMR data of (C5Me5)Lu(OArtBu,H)(Me)(d8-
1
3
THF)2 (8b). H NMR: d = 7.34 (d, JHH = 7.7 Hz, 2H,
3
Ar-Hmeta), 6.81 (t, JHH = 7.7 Hz, 1H, Ar-Hpara), 1.99 (s,
15H, C5Me5), 1.51 (s, 18H, CMe3), ꢁ0.41 (s, 3H, Lu–
Me). 13C{1H} NMR: d = 163.6 (Cipso), 138.0, 124.9,
117.6, 116.6 (C5Me5), 35.1 (CMe3), 31.5 (CMe3), 27.6
(Lu–Me), 11.5 (C5Me5).
4.2.6. Synthesis of (C5Me5)Y(OCH2CMe3)2(AlMe3)2
(12a)
In a glovebox, 0.199 g (0.25 mmol) of 11a were dissolved
in 10 mL of hexane, and a solution of 0.072 g (1.00 mmol)
of TMA in a small amount of hexane was added under stir-
ring. The mixture was stirred at ambient temperature for
1 h. Then, all volatiles were removed in vacuo and the res-
idue was crystallized from hexane at ꢁ45 ꢁC to yield 12a
(0.221 g, 0.41 mmol, 81%) as colorless crystals. IR (nujol):
m = 1404 w, 1366 s, 1313 w, 1215 w, 1192 m, 1040 s, 1015 s,
934 w, 896 w, 746 w, 697 s, 636 w, 585 m cmꢁ1. 1H NMR:
4.2.3.3. NMR data of (C5Me5)Y(OArtBu,Me)(Me)(d8-
THF)2 (9). 1H NMR: d = 7.19 (s, 2H, Ar-H), 2.28 (s,
3H, Me), 2.06 (s, 15H, C5Me5), 1.56 (s, 18H, CMe3),
2
ꢁ0.53 (d, JHY = 2.2 Hz, 3H, Y–Me). 13C{1H} NMR:
2
d = 161.4 (d, JCY = 4.6 Hz, Cipso), 137.7, 126.0, 123.4,
117.2 (C5Me5), 35.3 (CMe3), 31.6 (CMe3), 21.4 (Me), 21.3
1
(d, JCY = 58.4 Hz, Y–Me), 11.9 (C5Me5).
2
d = 3.69 (d, JHH = 10.1 Hz, 2H, CH2), 3.48 (d,
2JHH = 10.1 Hz, 2H, CH2), 1.90 (s, 15H, C5Me5), 0.91 (s,
18H, CMe3), ꢁ0.30 (s, br, 18H, AlMe3). 13C{1H} NMR:
d = 121.2 (C5Me5), 77.2 (CH2), 33.5 (CMe3), 27.2
(CMe3), 11.6 (C5Me5); AlMe3 not detected. Anal. Calc.
for C26H55Al2O2Y: C, 57.55; H, 10.22. Found: C, 57.38;
H, 10.08%.
4.2.3.4. NMR data of (C5Me4H)Y(OArtBu,Me)(Me)(d8-
THF)2 (10). 1H NMR: d = 7.20 (s, 2H, Ar-H), 5.91 (s, 1H,
C5Me4H), 2.27 (s, 3H, Ar-Me), 2.22 (s, 6H, C5Me4H), 1.96
(s, 6H, C5Me4H), 1.57 (s, 18H, CMe3), ꢁ0.67 (d,
2JHY = 2.4 Hz, 3H, Y–Me). 13C{1H} NMR: d = 161.3 (d,
2JCY = 4.6 Hz, Cipso), 137.5, 126.4, 123.3, 119.0

A. Fischbach et al. / Inorganica Chimica Acta 359 (2006) 4855–4864
4863
4.2.7. Synthesis of (C5Me5)Lu(OCH2CMe3)2(AlMe3)2
(12b)
parameters were obtained by the full-matrix least-squares
refinement of 3311 (3264) reflections. The data collection
were performed at 123 (123) K (OXFORD CRYOSYS-
Following the procedure of 12a, 0.242 g (0.25 mmol) of
11b and 0.072 g (1.00 mmol) of TMA yielded 0.243 g
(0.39 mmol, 77%) of 12b as colorless crystals. IR (nujol):
m = 1313 w, 1225 w, 1193 m, 1039 s, 1013 s, 935 w, 894
TEMS) within
a
h-range of 1.77ꢁ < h < 25.41ꢁ
(2.09ꢁ < h < 25.37ꢁ) and measured with eight (nine) data
sets in rotation scan modus with Du/Dx = 1.0ꢁ (1.0ꢁ). A
total number of 59557 (50100) intensities were integrated.
The raw data were corrected for Lorentz, polarization,
and, arising from the scaling procedure, for latent decay
and absorption effects. After merging [Rint = 0.090
(0.066)] a sum of 5832 (5755) (all data) and 5171 (5595)
[I > 2r(I)], respectively, remained and all data were used.
The structures were solved by a combination of direct
methods and difference Fourier syntheses. All non-hydro-
gen atoms were refined with the anisotropic displacement
parameters. The hydrogen atoms bound to the agostic
coordinated methyl groups at C1 and C4 together with
the protons of the methylene carbon atoms C7 and C12
were found in the difference Fourier maps and were
allowed to refine with individual isotropic displacement
parameters. All other hydrogen atoms were placed in ideal
positions and treated as riding atoms using SHELXL-97
default parameters. The full-matrix least-squares refine-
ments with 337 (337) parameters were carried out by min-
1
w, 749 w, 701 s, 588 m, 500 w cmꢁ1. H NMR: d = 3.73
2
2
(d, JHH = 10.9 Hz, 2H, CH2), 3.47 (d, JHH = 10.9 Hz,
2H, CH2), 1.92 (s, 15H, C5Me5), 0.91 (s, 18H, CMe3),
0.20 (s, 6H, l-Me), ꢁ0.37 (s, 12H, AlMe2). 13C{1H}
NMR: d = 120.0 (C5Me5), 77.6 (CH2), 33.5 (CMe3), 27.3
(CMe3), 11.6 (C5Me5), 7.0 (AlMe2); l-Me not detected at
ambient temperature. Anal. Calc. for C26H55Al2LuO2: C,
49.67; H, 8.82. Found: C, 50.00; H, 9.01%.
4.3. X-ray crystallographic study
Crystal data and details of the structure determination
of complexes (C5Me5)Y(OCH2CMe3)2(AlMe3)2 (12a) and
(C5Me5)Lu(OCH2CMe3)2(AlMe3)2 (12b) are presented in
Table 4. Suitable single crystals for the X-ray diffraction
studies were grown from hexane. A clear colorless plate
(12b: colorless plate) was selected in a glovebox, coated
with perfluorinated ether, and fixed in a capillary. A preli-
minary examination of the crystal quality and data collec-
tion were carried out on an area detecting system
(NONIUS, MACH3, j-CCD) in combination with a rotat-
ing-anode X-ray generator (NONIUS, FR591) and graph-
P
2
imizing
wðF 2o ꢁ F 2cÞ with the SHELXL-97 weighting
scheme and stopped at shift/error <0.001 (0.003). The final
residual electron density maps showed no remarkable
features. Neutral atom scattering factors for all atoms
and anomalous dispersion corrections for the non-
hydrogen atoms were taken from International Tables for
˚
ite-monochromated Mo Ka radiation (k = 0.71073 A)
employing the COLLECT software package [35]. The unit cell
Table 4
Crystal data and data collection parameters of complexes 12a and 12b
Compound
12a
12b
Formula
Formula weight
Color/habit
C
542.57
26H55Al2O2Y
C26H55Al2LuO2
628.63
colorless/plate
0.13 · 0.38 · 0.71
orthorhombic
P212121 (no. 19)
11.0616(1)
13.7955(1)
20.8147(2)
3176.33(5)
4
colorless/plate
0.13 · 0.48 · 0.56
orthorhombic
P212121 (no. 19)
11.0588(1)
13.7225(1)
20.6956(2)
3140.65(5)
4
Crystal dimensions (mm)
Crystal system
Space group
˚
a (A)
˚
b (A)
˚
c (A)
3
˚
V (A )
Z
T (K)
123
1.135
1.909
1168
123
1.329
3.217
1296
Dcalc (g cmꢁ3
)
l (mmꢁ1
F(000)
)
Range (ꢁ)
Index ranges (h, k, l)
Number of reflections collected
Number of independent reflections (Rint
1.77–25.41
13, 16, 25
59577
5832 (0.090)
5171
5832/0/337
0.0337/0.0664
0.0438/0.0697
1.010
2.09–25.37
13, 16, 24
50100
5755 (0.066)
5595
5755/0/337
0.0211/0.0544
0.0225/0.0552
1.053
)
Number of observed reflections [I > 2r(I)]
Number of data/restraints/parameters
R1/wR2 [I > 2r(I)]a
R1/wR2 (all data)a
Goodness-of-fit on F2a
ꢁ3
˚
Largest difference in peak and hole (e A
)
+0.26 and ꢁ0.28
+1.20 and ꢁ0.94
P
P
P
P
P
R1 = (iFoj ꢁ jFci)/ jFoj; wR2 ¼ f ½wðF o2 ꢁ F c2Þ ꢅ= ½wðF 2oÞ ꢅg1=2; Goodness-of-fit ¼ f ½wðF o2 ꢁ F 2c Þ ꢅ=ðn ꢁ pÞg
.
2
2
2
1=2
a

4864
A. Fischbach et al. / Inorganica Chimica Acta 359 (2006) 4855–4864
(c) H.J. Heeres, A. Meetsma, J.H. Teuben, Organometallics 8 (1989)
2637;
(d) H.J. Heeres, J.H. Teuben, Recl. Trav. Chim. Pays-Bas 109 (1990)
226.
Crystallography. All calculations were performed on an
Intel Pentium 4 PC, with the STRUX-V system, including
the programs PLATON, SIR-92, and SHELXL-97 [35]. As shown
by Flack’s parameter e = 0.496(5) [0.524(7)] both crystals
are twinned. The problem was solved by using the
SHELXL-97 TWIN/BASF procedure. A disorder over two
positions [12a: 0.60(4):0.40(4); 12b: 0.71(6):0.29(6)] of the
C5-methyl group could be resolved clearly.
[12] (a) C.J. Schaverien, J. Chem. Soc., Chem. Commun. (1992) 11;
(b) C.J. Schaverien, Organometallics 13 (1994) 69.
[13] Y. Yao, Q. Shen, J. Sun, F. Xue, Acta Crystallogr., Sect. C C54
(1998) 625.
[14] R.J. Butcher, D.L. Clark, J.C. Gordon, J.G. Watkin, J. Organomet.
Chem. 577 (1999) 228.
[15] H.J. Heeres, J.H. Teuben, R.D. Rogers, J. Organomet. Chem. 364
(1989) 87.
Acknowledgements
[16] (a) W.J. Evans, T.J. Boyle, J.W. Ziller, Organometallics 12 (1993)
3998;
(b) W.J. Evans, J.L. Shreeve, J.W. Ziller, Organometallics 13 (1994)
731.
[17] W.J. Evans, T.J. Boyle, J.W. Ziller, J. Organomet. Chem. 462 (1993)
141.
We thank the Deutsche Forschungsgemeinschaft, the
Fonds der Chemischen Industrie, and the Norwegian Re-
search Council for their generous support.
[18] (a) A. Fischbach, F. Perdih, P. Sirsch, W. Scherer, R. Anwander,
Organometallics 21 (2002) 4569;
Appendix A. Supplementary material
(b) A. Fischbach, F. Perdih, E. Herdtweck, R. Anwander, Organo-
metallics 25 (2006) 1626.
[19] A. Fischbach, E. Herdtweck, R. Anwander, G. Eickerling, W.
Scherer, Organometallics 22 (2003) 499.
[20] R. Harlow, P.L. Watson, Inorg. Chim. Acta 140 (1987) 15.
[21] H. Yamamoto, H. Yasuda, K. Yokota, A. Nakamura, Y. Kai, N.
Kasai, Chem. Lett. (1988) 1963.
Crystallographic data (excluding structure factors) for
the structures reported in this paper have been deposited
with the Cambridge Crystallographic Data Centre as sup-
plementary publication nos. CCDC-616614 (12a) and
CCDC-616615 (12b). Copies of the data can be obtained
free of charge on application to CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (fax: +44 1223 336 033; e-mail:
deposit@ccdc.cam.ac.uk or www: http://www.ccdc.ac.uk).
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.ica.2006.07.
090.
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