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Heterobimetallic Half-Lanthanidocene Clusters Novel Mixed TetramethylaluminatoChloro Coordination.

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Cluster Compounds
DOI: 10.1002/anie.200600905
Heterobimetallic Half-Lanthanidocene Clusters:
Novel Mixed Tetramethylaluminato/Chloro
H. Martin Dietrich, Oliver Schuster, Karl W. Trnroos,
and Reiner Anwander*
The beauty of symmetry has been a stimulus and driving force
for ligand-based cluster research.[1] By spanning the borderline between molecular and solid-state chemistry, large
nanosized inorganic clusters not only emulate intermediates
of sol–gel chemistry[2] but also contribute to a better understanding of the intriguing quantum-confinement phenom[*] H. M. Dietrich, Prof. K. W. T!rnroos, Prof. R. Anwander
Department of Chemistry
University of Bergen
All0gaten 41, 5007 Bergen (Norway)
Fax: (+ 47)-5558-9490
Dr. O. Schuster
Anorganisch-chemisches Institut
Technische UniversitAt MBnchen
Lichtenbergstrasse 4, 85747 Garching (Germany)
[**] Financial support from the Norwegian Research Council (Project No. 171245/V30), the program Nanoscience@UiB, and the
Fonds der Chemischen Industrie is gratefully acknowledged.
Supporting information for this article is available on the WWW
under or from the author.
2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2006, 45, 4858 –4863
enon of semiconductors.[3–5] Moreover, cluster molecules can
act as model systems for addressing delicate questions in
catalysis science by giving insight into unique coordination
modes and reactivities.[6, 7] In organometallic cluster chemistry, trailblazing structural reports such as those of the
inorganic fullerene-like molecule [{Cp*Fe(h5 :h1:h1:h1:h1:h1P5)}12{CuCl}10{Cu2Cl3}5{Cu(CH3CN)2}5][8] and low-valent aluminum complexes [Al50Cp*12] [9a] or [SiAl14Cp*6] [9b] bear
witness to the uniqueness of the ubiquitous cyclopentadienyl
ancillary ligand environment in d-transition-metal and maingroup-metal chemistry (Cp* = C5Me5).[10] Because of its steric
bulk, rigidity, and thermal and chemical stability, the Cp ligand and its substituted variants are also ideal for cluster
design/stabilization involving the large oxophilic rare-earth
metal ions, which participate predominantly in ionic bonding.[11] While hydrolysis- or oxophilicity-driven cluster formation meanwhile includes numerous structurally characterized examples—Ln nuclearities as high as 15, as in [Eu15(Cl)(m3-Tyr)10(m3-OH)20(m2-H2O)5(OH)12(H2O)8][ClO4]2·56 H2O
(Tyr = tyrosine), were identified[12, 13]—the feasibility of Cpderived organolanthanide clusters is directed by the ratio Cp/
Ln < 2.[11] Accordingly, half-lanthanidocene complexes
should exhibit prolific cluster chemistry.[14] Table 1 summarizes such half-sandwich clusters, which are highlighted by
[(Cp)12Sm12(m3-Cl)24] and [{(Me4CpSiMe3)Ln(m-H)2}4] (Ln =
Y, Lu).[15–36] The latter hydrido clusters are rare examples of
organolanthanide clusters which feature highly reactive
Recently we described a convenient method for the
synthesis of half-sandwich complexes [Cp*Ln(AlMe4)2] (1),
which comprise small and large rare-earth-metal centers.[37]
The study herein shows that such well-defined, thermally
stable, and highly soluble bis(aluminate) complexes offer
access to unprecedented heteroleptic organolanthanide cluster chemistry. Compared to the lanthanidocene-based
[Cp*2Sm(thf)x]/R2AlCl and [Cp*2LnCl]/R3Al (Ln = Y, Sm;
R = Me, Et, iBu) reaction mixtures, which produce homo(“Ln(m-Cl)2AlR2”)
(“Ln(m-R)(mCl)AlR2”) moieties,[38] the half-lanthanidocene system 1/
Me2AlCl leads to intrinsic AlMe4/Cl ligand exchange and
variable Ln nuclearity, depending on the size of the
LnIII metal. Furthermore, the “open” coordination sphere of
monocyclopentadienyl complexes facilitates novel coordination modes of the AlMe4 ligand.
Treatment of [Cp*Ln(AlMe4)2] (1 a: Ln = Y, 1 b: Ln = La,
1 c: Ln = Nd) with varying amounts of Me2AlCl in hexane led
to crystalline materials of net composition [Cp*Ln(AlMe4)x(Cl)y] (2: Ln = Y, x = y; 3: Ln = La, y = 2 x; 4: Ln =
Nd, y = 9 x) as indicated by elemental analysis (Scheme 1).
Though the white and bluish materials obtained for the larger
rare-earth-metal centers are completely insoluble in benzene
and toluene, the colorless yttrium derivative 2 slightly
dissolves in aromatic solvents. The 1H NMR spectrum of 2
in C6D6 revealed Cp* (d = 1.91 ppm) and AlMe4 signals (d =
0.15 ppm) which were slightly shifted to higher field relative
to the precursor compound 1 a (d = 1.76 and 0.34 ppm),
albeit with the same 2JY,H coupling constant of 2.4 Hz as for
1 a. The sharp doublet of the aluminate group is indicative of a
highly fluxional behavior with fast exchange of bridging and
Angew. Chem. Int. Ed. 2006, 45, 4858 –4863
Table 1: Structurally
[Yb5Cp5(m5-O)(m3-OCH3)4(m-OCH3)4] (Ln = Yb, Gd)
[Ln6(C5Me4nPr)6(BH4)(12 x)Clx(thf)n] (Ln = Sm, Nd; x = 0, 5, 10)
[Ln4(C5Me4SiMe3)4(m-H)8](thf)n (Ln = Lu, Y)[d]
[La3Cp*3(m-h2 :h6 :h6-C16H10)(m-Cl)3(thf)][e,f ]
[Y3Cp*3(m-Me)6][f ]
[Cp*4Y4(m2-CH3)2{(CH3)Al(m2-CH3)2}4(m4-CH)2][f ]
[Nd5Cp*5{(m-Me)3AlMe}(m4-Cl)(m3-Cl)2(m-Cl)6] (4)
[La6Cp*6{(m-Me)3AlMe}4(m3-Cl)2(m2-Cl)6] (3)
[a] H2acacen = bis(acetone)ethylenediamine,
H2saltn = bis(salicylidene)trimethylenediamine. [b] 2,4-C7H11 = 2,4-dimethylpentadienyl. [c] YbII
center. [d] Subsequent reactions gave imido clusters [Lu4(C5Me4SiMe3)4(m-NCH2C6H5)4] and [Y4(C5Me4SiMe3)4(m-NCH3)4(m-NCC6H5)4] as well as
partially exchanged hydrido clusters [Y4(C5Me4SiMe3)4(m-H)7(C7H7)],
(CH2)4O)] and completely exchanged clusters [Y4(C5Me4SiMe3)4(m3O)2(Me3SiCCHCHCSiMe3)],
[Y4(C5Me4SiMe3)4(m-CH2O2)2(Me3SiCCHCHCSiMe3)], [Y4(C5Me4SiMe3)4(m-CH2O2)(m-CO3)(Me3SiCCHCHCSiMe3)],
[e] Deprotonated pyrene ligand. [f ] Metal-ring arrangement. [g] This
terminal methyl groups. Molar ratios of 1 a/Me2AlCl < 0.9 in
the reactions gave increasing amounts of amorphous white
solid, which was not further characterized. Examination of
the hexane-soluble fractions by NMR spectroscopy only
revealed AlMe3 as a coproduct as well as unreacted 1 and
Me2AlCl. Complexes 2–4 were further characterized by the
signal patterns of their IR spectra, which featured few bands
and weak signal intensities, and their solid-state structures.
X-ray structure analysis of complex 2 revealed the dimeric
complex [{Cp*Y[(m-Me)2AlMe2](m-Cl)}2] (Figure 1) with formally heptacoordinate yttrium centers and a rare combination of homometal-bridging chloride ligands and h2-coordinated aluminate ligands (Al1 lies 0.207(3) I out of the
2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Scheme 1. Reaction pathways of [Cp*Ln(AlMe4)2] (1 a: Ln = Y, 1 b:
Ln = La, 1 c: Ln = Nd) with Me2AlCl.
least-squares C3-Y1-C4 plane).[39] The average Y C(m-Me)
bond length (2.573 I) is slightly larger than that in hexacoordinate [Y(AlMe4)3] (2.508 I).[40] The Y Cl bond lengths
(2.6326(9), 2.7177(9) I) are comparable to the corresponding
bond lengths for the bridging chloro ligand in hepta-/
2.776(6) I).[41]
Lanthanum complex 3 was reproducibly obtained as
colorless crystals for a relatively wide range of La/Al ratios,
and the reaction with 0.9 equivalents of Me2AlCl gave an
almost quantitative yield (Scheme 1). Three independent Xray crystallographic studies[39] proved the formation of the
hexalanthanum cluster [Cp*6La6{(m-Me)3AlMe}4(m3-Cl)2(m2Cl)6] (Figure 1) and, hence, an “over-exchange” of aluminate
ligands. The La6Al4 hetero-bimetallic cluster is composed of
two {Cp*3La3Cl4} subunits which are connected by a strand of
four AlMe4 ligands and can thus be described by the formula
[Cp*3La3Cl4]2(m-AlMe4)4. Each lanthanum center is octacoordinate and bound by one Cp* ligand, three chloro ligands, and
two methyl groups of the aluminate strand. The bridging
chloro ligands are arranged in the form of a distorted
tetrahedron. The average La Cl bond lengths of 2.8280 I
(m2-Cl) and 3.0444 (m3-Cl) are in the range of those in
[La3Cp*3(m-h2 :h6 :h6-C16H10)(m-Cl)3(thf)]
2.894(2) I).[33] Two lanthanum centers of each equilateral
La3 triangle are coordinated by an AlMe4 group in h2 mode.
The same two aluminate groups interact with the third
lanthanum center of the other La3 subunit in h1 fashion. The
planar LaMe2Al (Al1 lies 0.088(4) I out of the least-squares
C31-La1-C32 plane and Al2 0.045(4) I out of the leastsquares C37-La3-C38 plane) and almost linear La-Me-Al
(av. 170.08) hetero-bimetallic units combine to give an
unprecedented {La(m-Me2)Al(Me)(m-Me)La} hetero-trinuclear arrangement. The La C(m-Me)[h1] bonds (2.950(3) I)
are significantly longer than the La C(m-Me)[h2] bonds
(av. 2.795 I). For comparison, the La C(m-Me) bond lengths
in [Cp*La{(m-Me)2AlMe2}2] range from 2.694(3) to
2.802(4) I.[37b] The Al C bond lengths decrease gradually in
the order m-Me[h2] (2.042 I) > m-Me[h1] (2.013 I) > terminal
(1.967 I). Similar hexalanthanide (CpLn)6 cluster arrangements have been isolated in the presence of borohydrido
coligands (Table 1).[29]
Blue-green single crystals of neodymium complex 4 were
obtained within one day from unstirred reaction mixtures.
Two independent X-ray crystallographic studies showed that
the pentanuclear neodymium cluster [Cp*5Nd5[(mMe)3AlMe](m4-Cl)(m3-Cl)2(m2-Cl)6] was formed with a low
Nd/Cl ratio of 1:1.7 (Figure 1).[39] Each neodymium center is
octacoordinate; however, three different neodymium environments are observed. Four of the Nd atoms adopt a
butterfly arrangement with two different “Cp*NdCl5” coordination polyhedra. The Nd4 unit is connected to the fifth
Nd atom through two m2-bridging chloro ligands, and the
pseudotetrahedral coordination geometry of this atom is
completed by a Cp* ligand and an AlMe4 ligand. A similar
cluster geometry was previously found in [Yb5Cp*6(m4-F)(m3F)2(m-F)6], in which fluoro instead of chloro ligands are
involved and the tetramethylaluminato ligand is replaced by a
second Cp* ligand.[23] The most striking feature of the Nd5Al
cluster is the h3-coordinated tetramethylaluminate group,
which has three similar Nd C(m-Me) bond lengths (2.878(18),
2.875(16), 2.779(16) I) and a short Nd···Al separation of
2.920(5) I. These Nd C bonds are significantly longer than
the h2-coordinated Nd C(m-Me) bonds in hexacoordinate
[Nd(AlMe4)3] (av. Nd C bond length: 2.592 I).[40] To our
knowledge, no structural evidence of a true h3 coordination of
an AlMe4 group to a lanthanide center has been reported so
far.[42] The average Nd Cl bond lengths increase with the
degree of metal bridging in the order 2.775 (m2-Cl), 2.921 (m3Cl), and 2.980 I (m4-Cl) and are comparable to the range of
[(m2-Cl);(m3-Cl)] bond lengths in [Nd6(2,4-C7H11)6Cl12(thf)2]
(2.759(2)–2.934(1) I).[24]
In conclusion, complexes 2–4 feature rare examples of
alkali-metal-free organolanthanide complexes which contain
both alkyl and chloro ligands.[43] The open half-lanthanidocene coordination sphere facilitates new coordination modes
C and E of the tetramethylaluminate ligand (Figure 2), which
exhibit extremely long Ln C bond lengths.
2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2006, 45, 4858 –4863
Figure 1. Molecular structures of 2–4 (atomic displacement parameters set at the 50 % level). Atoms of the Cp* groups are shown isotropically
with an arbitrary radius and without H atoms. Underlined atom labels indicate symmetry-related atoms. For 3 only the first of the two unique half
molecules is shown. For 4 the methyl groups of the cyclopentadienyl ligands at Nd1–Nd4 were omitted for clarity. Selected bond distances [O]
and angles [8]: 2: Y1-Al1 3.0584(12), Y1-Cl1 2.6326(9), Y1-Cl1’ 2.7177(9), Y1-C3 2.554(3), Y1-C4 2.592(3), Y1-C(Cp*) 2.567(4)–2.610(4), Al1-C1
1.954(5), Al1-C2 1.897(4), Al1-C3 2.138(3), Al1-C4 2.106(4); Cl1-Y1-Cl1’ 82.14(3), Y1-Cl1-Y1’ 97.86(3), C3-Y1-C4 86.14(10), Y1-C3-Al1 80.83(9) C3Al1-C4 111.79(12). 3: La1/4-Al1/3 3.3531/3.3534(11), La3/6-Al2/Al4 3.3186/3.3150(11), La1/4-Cl1/5 2.8355/2.8263(9), La1/4-Cl3/7 2.8170/
2.8179(10), La1/4-Cl4/8 3.0565/3.0504(8), La2/5-Cl1/5 2.8232/2.8049(9), La2/5-Cl2/6 2.8197/2.8153(9), La2/5-Cl4/8 3.0060/3.0067(7), La3/6-Cl2/
6 2.8439/2.8373(9), La2/6-Cl3/7 2.8284/2.8339(10), La3/6-Cl4/8 3.0708/3.0652(8), La1/4-C31/69 2.819/2.826(4), La1/4-C32/70 2.799/2.783(4),
La2/5-C34/72 2.950/2.955(3), La2/5-C36/74 2.950/2.938(3), La3/6-C37/76 2.790/2.774(4), La3/6-C38/75 2.771/2.784(4), La-C(Cp*) 2.728(3)–
2.819(4), Al1/3-C31/69 2.044/2.040(4), Al1/3-C32/70 2.042/2.040(4), Al1/3-C36/74 2.010/2.015(4), Al1/3-C33/71 1.969/1.976(4), Al2/4-C37/76
2.041/2.045(4), Al2/4-C38/75 2.042/2.044(4), Al2/4-C34/72 2.016/2.014(3), Al2/4-C35/73 1.965/1.963(4); La1/4–Cl1/5-La2/5 110.96/110.94(3),
La2/5-Cl2/6-La3/6 111.85/111.72(3), La1/4-Cl3/7-La3/6 113.19/113.07(3), La1/4-Cl4/8-La2/5 100.53/99.97(2), La1/4-Cl4/8-La3/6 100.55/100.88(2),
La2/5-Cl4/8-La3/6 101.05/100.80(2), La1/4-C31/69-Al1/3 85.61/85.52(1), C31/69-La1/4-C32/70 74.78/74.65(1), La2/5-C36/74-Al1/3 168.77/
168.84(2), La2/5-C34/72-Al2/4 170.70/171.63(2). 4: Nd5-Al 2.920(5), Nd5-C51 2.878(18), Nd5-C52 2.875(16), Nd-C53 2.779(16), Nd-Cl(m2)
2.731(4)–2.809(4), Nd-Cl(m3) 2.866(4)–3.000(4), Nd-Cl(m4) 2.961(4)–3.005(4), Nd-C(Cp*) 2.650(15)–2.728(17); Nd5-C51-Al 70.7(5), C51-Nd5-C52
69.4(6), Nd5-Cl2-Nd1 132.48(15), Nd5-Cl6-Nd4 131.71(16), Cl2-Nd5-Cl6 119.44(12), Nd1-Cl9-Nd4 175.17(14), Nd2-Cl9-Nd3 91.00(10), Nd2-Cl4Nd3 94.89(11), Nd1-Cl3-Nd2 96.40(12) Cl1-Nd1-Cl3 143.54(12).
We recently reported that the binary system [Ln(AlMe4)3]/Me2AlCl acts as a highly efficient initiator for
isoprene polymerization.[44] Those findings were in accordance with a) chloro transfer to an alkylated rare-earth-metal
center as the crucial activation step and b) the fact that
neodymium is the most active rare-earth-metal center (“neodymium effect”).[45] Our findings that subtle changes in rareearth-metal size considerably affect the AlMe4/Cl exchange
Angew. Chem. Int. Ed. 2006, 45, 4858 –4863
and coordination behavior of the AlMe4 ligand, might provide
more insight into the obscure neodymium effect. Both binary
[Ln(AlMe4)3]/Me2AlCl and commercially employed ternary
[Ln(carboxylate)3]/HAliBu2/Et3Al2Cl3 “Ziegler mixed catalysts” initially produce a fine precipitate upon addition of the
chloro-ligand source which redissolves upon addition of diene
monomer.[44, 46] Clearly, such an activation scenario suggests
that cluster formation is part of the initiating steps.
2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Keywords: alkyl aluminates · cluster compounds · rare earths ·
structure elucidation
Figure 2. Structurally characterized Ln AlMe4 coordination modes.
Experimental Section
2: In a glovebox, [Cp*Y(AlMe4)2] (1 a, 200 mg, 0.50 mmol) was
dissolved in hexane (5 mL). Without stirring, a solution of Me2AlCl
(452 mL, 1m in hexane, 0.9 equiv) was added at 35 8C. Within 5 h at
ambient temperature the product was obtained as colorless crystals
(77 mg, 49 % based on Me2AlCl). After 7 days, an additional crop
(45 mg) was isolated from the solution, thus resulting in an overall
yield of 78 %. The product was slightly soluble in toluene and
benzene. Impurities of [Cp*Y(AlMe4)2] were best separated from the
product by washing with small amounts of toluene. According to
H NMR spectroscopic analysis, this transformation gave pure
products for 0.5–0.9 equiv of Me2AlCl. The product was also obtained
from a stirred reaction mixture as a white solid in good yield. IR
(nujol): ñ = 1211 (m), 1189 (m), 1169 (m), 1021 (w), 965 (w), 769 (w),
578 (w), 477 cm 1 (w); 1H NMR (400 MHz, [D8]toluene, 25 8C): d =
1.91 (s, 15 H, Cp*), 0.16 ppm (d, 12 H, AlMe4); 13C{1H} NMR
(100 MHz, [D8]toluene, 25 8C): d = 122.2 (C5Me5), 11.3 ppm (C5Me5).
Elemental analysis (%) calcd for C28H54Al2Cl2Y2 (693.416 g mol 1):
C 48.50, H 7.85; found: C 47.79, H 7.60.
3: In a glovebox, [Cp*La(AlMe4)2] (1 b, 200 mg, 0.45 mmol) was
dissolved in hexane (5 mL). Without stirring, a solution of Me2AlCl
(446 mL, 1m in hexane, 1 equiv) was added at 35 8C. The formation
of single crystals was observed within 30 min at ambient temperature.
Within 2 days the product was obtained as colorless crystals (130 mg,
> 95 % based on Me2AlCl). According to elemental analysis and Xray analysis, the reaction resulted in the pure product for 0.5–
1.3 equiv of Me2AlCl. The product was also obtained from a stirred
mixture as a white solid in quantitative yield. IR (nujol): ñ = 1305 (m),
1190 (m), 1042 (m), 1027 (m), 967 (w), 769 (w), 722 (m), 702 (m), 623
(m), 585 (w), 532 cm 1 (w). Elemental analysis (%) calcd for
C76H138Al4Cl8La6·C6H14 (2363.119 g mol 1): C 41.68, H 6.48; found:
C 42.11, H 6.64.
4: Following the above procedure, blue-green crystals (36 mg,
21 % based on 1 c) were obtained within 24 h from 1 c (200 mg,
0.46 mmol) and Me2AlCl (528 mL, 1m in hexane, 1.2 equiv). According to the elemental analysis, the product was formed also by addition
of 1.2–1.7 equiv of Me2AlCl. IR (nujol): ñ = 1305 (m), 1190 (m), 1042
(m), 1027 (m), 967 (w), 769 (w), 722 (m), 702 (m), 623 (m), 585 (w),
532 cm 1 (w). Elemental analysis (%) calcd for C54H87AlCl9Nd5·C6H14
(1889.721 g mol 1): C 38.14, H 5.39; found: C 37.61, H 5.21.
Full experimental and physicochemical details for complexes 2–4
are available in the Supporting Information.
Received: March 8, 2006
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[39] Compound 2 (C28H54Al2Cl2Y, Mr = 693.39) crystallized from
hexane in the triclinic space group P1̄, a = 8.6804(6), b =
10.2662(8), c = 10.3573(6) I, a = 69.501(3), b = 86.674(7), g =
84.192(3)8, V = 859.85(10) I3, 1calcd = 1.331 g cm 3, Z = 1. Data
were collected at 143 K on a Nonius DIP 2020 system. The
structure was solved by Patterson methods, and least-square
refinement of the model based on 2966 (all data) and 2653
reflections (I > 2.0s(I)) converged to the final values wR2 =
0.1108 and R1 = 0.0417. Compound 3 (C82H152Al4Cl8La6·hexane,
Mr = 2363.02) crystallized from hexane in the triclinic space
group P1̄, a = 14.5831(6), b = 15.8066(7), c = 24.8320(10) I, a =
80.097(1), b = 85.614(1), g = 65.919(1)8, V = 5147.9(4) I3, 1calcd =
1.524 g cm 3, Z = 2. Data were collected at 153 K on a
BRUKER-AXS 2 K CCD system. The structure was solved by
direct methods, and least-square refinement of the model based
on 24 553 (all data) and 21 252 reflections (I > 2.0s(I)) converged
to the final values wR2 = 0.0795 and R1 = 0.0309. The asymmetric unit contains two independent half molecules (La1–La3
etc. and La4–La6 etc.) that are related by inversion centers into
two full complexes (symmetry operations 2 x, y, 2 z and x,
1 y, 3 z) and one hexane solvate molecule. Compound 4
(C60H101AlCl9Nd5·hexane, Mr = 1889.64) crystallized from
hexane in the triclinic space group P1̄, a = 12.3712(15), b =
13.7414(17), c = 24.038(3) I, a = 75.839(2), b = 84.498(2), g =
66.827(2)8, V = 3642.5(8) I3, 1calcd = 1.723 g cm 3, Z = 2. Data
were collected at 123 K on a BRUKER-AXS 2K CCD system.
Angew. Chem. Int. Ed. 2006, 45, 4858 –4863
The structure was solved by direct methods, and least-square
refinement of the model based on 14 871 (all data) and 11 427
reflections (I > 2.0s(I)) converged to the final values wR2 =
0.2232 and R1 = 0.0886. Compounds 3 and 4 each cocrystallized
with a molecule of hexane which could not be removed in high
vacuum. All hydrogen atoms of the methyl groups that are
bonded to aluminum centers were found in the difference
Fourier maps but were thereafter placed in calculated positions
(SHELXL riding models AFIX 33 and 137) for structures 3 and
4. For compound 2 the hydrogen atoms of the coordinating
methyl groups were refined. CCDC-600834–600836 contain the
supplementary crystallographic data for this paper. These data
can be obtained free of charge from The Cambridge Crystallographic Data Centre via
W. J. Evans, R. Anwander, J. W. Ziller, Organometallics 1995, 14,
W. J. Evans, T. T. Peterson, M. D. Rausch, W. E. Hunter, H.
Zang, J. L. Atwood, Organometallics 1985, 3, 554.
h3-Coordinated AlEt4 groups were found in [{Al3Nd6(m-Cl)6(m3Cl)6(m-C2H5)9(C2H5)5(OiPr)}2][7] and [{Yb(AlEt4)2}n]: M. G.
Klimpel, R. Anwander, M. Tafipolsky, W. Scherer, Organometallics 2001, 20, 3983.
a) For a half-lutetocene complex with mixed chloro/donorfunctionalized alkyl ligands, see: H. Schumannn, J. A. MeeseMarktscheffel, A. Dietrich, J. Pickardt, J. Organomet. Chem.
1992, 433, 241; b) for a b-diketiminato samarium complex with
mixed chloro/tetramethylaluminate ligands, see: C. Cui, A.
Shafir, J. A. R. Schmidt, A. G. Oliver, J. Arnold, Dalton Trans.
2005, 1387.
A. Fischbach, M. G. Klimpel, M. Widenmeyer, E. Herdtweck, W.
Scherer, R. Anwander, Angew. Chem. 2004, 116, 2284; Angew.
Chem. Int. Ed. 2004, 43, 2234.
R. Taube, G. Sylvester in Applied Homogeneous Catalysis with
Organometallic Compounds (Eds.: B. Cornils, W. A. Herrmann),
Wiley-VCH, Weinheim, 2000.
W. J. Evans, D. G. Giarikos, J. W. Ziller, Organometallics 2001,
20, 5751.
2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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clusters, coordination, tetramethylaluminatochloro, lanthanidocene, novem, heterobimetallic, half, mixed
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