Rare earth metal benzyl complexes bearing bridged-indenyl ligand for highly active polymerization of methyl methacrylate

Article abstract of DOI:10.1016/j.jorganchem.2009.04.033

The novel anionic bridged-indenyl rare earth metal benzyl complexes [{C₉H₆SiMe₂(CH₂)₂SiMe₂C₉H₆}Ln(CH₂C₆H₄-p-^tBu)₂

Full text of DOI:10.1016/j.jorganchem.2009.04.033

Journal of Organometallic Chemistry 694 (2009) 2976–2980
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Rare earth metal benzyl complexes bearing bridged-indenyl ligand for highly
active polymerization of methyl methacrylate
a,
Dan Lin a,b, Jue Chen a, Chengcai Luo a, Yong Zhang b, Yingming Yao b, , Yunjie Luo
*
*
a Organometallic Chemistry Laboratory, Ningbo Institute of Technology, Zhejiang University, Ningbo 315100, China
b College of Chemistry, Chemical Engineering and Material Science, Suzhou University, Suzhou 215123, China
a r t i c l e i n f o
a b s t r a c t
Article history:
The novel anionic bridged-indenyl rare earth metal benzyl complexes [{C9H6SiMe2(CH2)2Si-
Me2C9H6}Ln(CH2C6H4-p-tBu)2][Li(THF)4] (Ln = Y (1), Lu (2)) were synthesized by an acid–base reaction
of C9H7SiMe2(CH2)2SiMe2C9H7 with one equiv. of rare earth metal trisbenzyl complexes, which were
formed in situ from the reaction of anhydrous LnCl3 with LiCH2C6H4-p-tBu in 1:3 molar ratio in THF.
The complexes were characterized by elemental analysis, NMR spectroscopy, FT-IR spectroscopy, and
X-ray structural analysis in the case of 2. Both complexes are active for the polymerization of methyl
methacrylate (MMA) to afford high molecular weight and narrow molecular weight distribution PMMA.
The molecular weights of PMMA could be controlled using 1 as a polymerization initiator in chloroben-
zene at À40 °C.
Received 23 February 2009
Received in revised form 24 April 2009
Accepted 28 April 2009
Available online 5 May 2009
Keywords:
Bridged-indenyl ligand
Organo rare earth metal benzyl complexes
Synthesis
Ó 2009 Elsevier B.V. All rights reserved.
Crystal structure
MMA polymerization
1. Introduction
2. Results and discussion
Organo rare earth metal complexes have witnessed rapid pro-
gress during the past two decades, and have played promising role
in the polymerization of both nonpolar and polar monomers [1–4].
In the 1990s, Yasuda and coworkers first reported that organo rare
earth metal derivatives, (C5Me5)2LnR (R = alkyl, H), could serve as
effective single-component catalysts for methyl methacrylate
(MMA) polymerization, giving highly syndiotactic poly(MMA) in
a living polymerization manner [5,6]. Since then, various kinds of
2.1. Synthesis and characterization of the ligand
The bridged-indenyl ancillary ligand C9H7SiMe2(CH2)2SiMe2C9H7
was synthesized by the reaction of freshly prepared indenyl lithium
(C9H7Li) with 0.5 equiv. of 1,2-bis(chlorodimethylsilyl)ethane in
hexane at room temperature, as shown in Scheme 1. After workup,
C9H7SiMe2(CH2)2SiMe2C9H7 was obtained as white powder in 96%
isolated yield. It was characterized by NMR spectroscopy, elemental
analysis, and FT-IR spectroscopy. 1H and 13C NMR spectra confirmed
that two indenes were connected by 1,4-disilabutylene group
through two sp3-hybridized carbons in each five-membered ring.
rare earth metal complexes containing Ln–C, Ln–N, or Ln–H
r-
bonds have been investigated for MMA polymerization [7–10].
Very recently, it was found that anionic rare earth metal complexes
could exhibit much higher activity than the corresponding neutral
ones in the polymerization of MMA [11–15]. However, the re-
ported anionic rare earth metal complexes showed poor ability
to control polymer molecular weights. On the other hand, while
a large spectrum of rare earth metal complexes with different
electronic and steric configurations have been well documented,
the bridged-indenyl-ligated rare earth metal complexes are rela-
tively limited [16–27]. Herein, we would like to report the novel
anionic bridged-indenyl rare earth metal benzyl complexes, as well
as their extremely high activity for the polymerization of methyl
methacrylate with molecular weights controllable under certain
conditions.
2.2. Synthesis and characterization of
[{C9H6SiMe2(CH2)2SiMe2C9H6}Ln(CH2C6H4-p-tBu)2][Li(THF)4] (Ln = Y
(1), Lu (2))
Treatment of C9H7SiMe2(CH2)2SiMe2C9H7 with 1 equiv. of rare
earth metal trisbenzyl complexes, which were formed in situ from
the reaction of LnCl3 with LiCH2C6H4-p-tBu in 1:3 molar ratio in
THF, afforded the bridged-indenyl rare earth metal benzyl
complexes [{C9H6SiMe2(CH2)2SiMe2C9H6}Ln(CH2C6H4-p-tBu)2][Li(THF)4]
(Ln = Y (1), Lu (2)) as pale yellow crystals in 53–59% isolated yields
(Scheme 2). Both complexes were characterized by elemental
analysis, FT-IR spectroscopy, and NMR spectroscopy. Single crystal
structural determination of 2 revealed that it is an anionic
complex.
* Corresponding authors. Tel.: +86 574 88130085; fax: +86 574 88130130.
E-mail address: lyj@nit.zju.edu.cn (Y. Luo).
0022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.04.033

D. Lin et al. / Journal of Organometallic Chemistry 694 (2009) 2976–2980
2977
Li
H
H
H
0.5 equiv. ClSiMe2(CH2)2SiMe2Cl
hexane, 17 h, r. t.
n
-BuLi
hexane, 7 h, r. t.
H
H
Si
Si
Scheme 1.
CH2Li
H
H
3
Si
(THF)4
Si
Ln
Li
0.5
tBu
LnCl3
THF, r. t.
THF, r. t.
tBu
tBu
Ln = Y (1), Lu (2)
Scheme 2.
Fig. 1. Molecular structure of 2 (10% probability thermal ellipsoids). Hydrogen atoms are omitted for clarity. Selected bond distances (Å) and bond angle (°): Lu(1)–C(1)
2.662(7), Lu(1)–C(2) 2.627(8), Lu(1)–C(3) 2.679(8), Lu(1)–C(4) 2.827(7), Lu(1)–C(9) 2.772(7), Lu(1)–C(10) 2.732(8), Lu(1)–C(11) 2.626(8), Lu(1)–C(12) 2.601(8), Lu(1)–C(13)
2.690(8), Lu(1)–C(18) 2.772(8), Lu(1)–C(25) 2.406(8), Lu(1)–C(36) 2.391(8); C(36)–Lu(1)–C(25) 89.1(3).
Both 1 and 2 are sensitive to air and moisture. However, no
decomposition was observed when they were kept in the glove
box at ambient temperature for couple of weeks. They are quite
soluble in THF and chlorobenzene, sparely soluble in toluene, but
insoluble in aliphatic hydrocarbon solvents, such as hexane and
pentane.
sidering the DLu–C(indenyl) defined as the difference of the longest and
the shortest bond distances between the lanthanide ion and the
indenyl ligand, the DLu–C(indenyl) values are 0.17 and 0.20 Å for the
two indenyl groups, suggesting the bonding mode of the metal ion
with indenyl ligands being partially slipped toward
g
3- from
g
5-mode, as found in rac-[O(CH2CH2C9H6)2]YbN(SiMe3)2 [23], and
Single crystals of 2 suitable for X-ray diffraction were grown from
a mixturesolutionofTHF/toluene inca. 1:2 volumeratioatÀ30 °C. Its
molecular structure, with the selected bond lengths and angles, is
shown in Fig. 1. X-ray structural analysis revealed that 2 exists as
crystallographically independent cation [Li(THF)4]+ and anionic pair
[{C9H6SiMe2(CH2)2SiMe2C9H6}Lu(CH2C6H4-p-tBu)2]À in the unit cell.
The central metal Lu3+ is coordinated by two five-membered rings
(Cp ring) of indenyl ligands and two methylene carbons of benzyl
groups. The coordination geometry around the Lu3+ can be described
as a distorted tetrahedron if the two indenyl rings, C25, and C36 are
regarded as occupying an independent polyhedral vertex. The Lu–
C(indenyl) bond distances range from 2.627(8) to 2.827(7) Å
(C1C2C3C4C9) and 2.601(8) to 2.772(8) Å (C10C11C12C13C18). Con-
meso-[O(CH2CH2C9H6)2]Yb(DME) [24]. Taking into consideration of
effective ionic radius [28], the bond distances of Lu–C(benzyl)
(2.406(8) and 2.391(8) Å) are comparable with those in rare earth
metal bis(benzyl) complexes, such as [PhC(N-2,6-iPr-C6H3)2]
La(CH2Ph)2(THF) (2.590(5)–2.632(3) Å) [29], [Me2TACNSiMe2NtBu]
La(CH2Ph)2 (2.687(4)–2.699(4) Å) and [tBuC(N-2,6-iPr-C6H3)2]
La(CH2Ph)2(THF) (2.595(3)–2.585(3) Å) [30].
2.3. Polymerization of MMA
To investigate the reactivity of 1 and 2, they were employed as
initiators for the polymerization of MMA under various conditions.
The results are summarized in Table 1. The complexes showed

2978
D. Lin et al. / Journal of Organometallic Chemistry 694 (2009) 2976–2980
much higher activity for MMA polymerization than the other
bridged-indenyl rare earth metal complexes [23,24], and the activ-
ity reached up to 48,000 mol of MMA/(mol LnÁh), which can com-
pete for the most active anionic rare earth metal complexes for
MMA polymerization reported to date [11–15]. The central metal
has a great influence on the activity. For example, the conversion
reached 100% in 1 min in the loading of [M]/[Ln] = 1000 at
À40 °C using 1 as the initiator, while the conversion was only 9%
for 2 even the polymerization was prolonged to 30 min (Entries 3
and 4, Table 1). This activity order, as observed in other lanthanido-
cene initiation systems for MMA polymerization [6], may be con-
tributed to that the ionic radii of Y (0.900 Å) is larger than of Lu
(0.861 Å) [28]. Although the polymerization could proceed at a
wide range of polymerization temperature (from À78 to 35 °C),
the polymerization activity was strongly dependent on the poly-
merization temperature. For example, when the polymerization
temperature was raised from À40 to 0 °C, the conversion of mono-
mer to polymer ranged from 100% to 56% in the case of the poly-
merization was terminated in one minute. However, when the
temperature was performed at 35 °C, the yield of polymer was only
40% even the polymerization was prolonged to 1 h (Entry 4, 8 and
9). This may be ascribed to that the nucleophilic substitution of
carbonyl group of MMA by the benzyl group is prohibited at lower
temperature [31]. As expected, the polymerization activity de-
creased dramatically as the polymerization was performed in polar
solvent, such as THF [32].
Fig. 2. Mn and Mw/Mn vs [MMA]/[Y] plots for MMA polymerization using 1 as an
initiator in chlorobenzene at À40 °C.
the molecular weights controllable. However, different to the poly-
merization carried out in chlorobenzene, in which 1 has good sol-
ubility, the polymerization performed in toluene or in bulk
afforded polymers with relatively broad molecular weight distri-
bution (Entries 5–7), partially owing to the heterogeneous
polymerization.
Triad microstructural analysis of the resulting polymers was
carried out using 1H NMR in CDCl3 according to the literature
[33]. The present initiation system showed poor control of stereo-
regularity in the polymerization, and yielded atactic PMMA.
The polymers obtained with 1 and 2 have high molecular
weights (Mn > 104) and relatively narrow molecular weight distri-
butions. In all cases, GPC curves showed a unimodal pattern, indic-
ative of single-site catalyst behavior. It is noteworthy that, albeit
with relatively low initiating efficiency (ca. 27% based on the
assumption of both Ln–C(benzyl) bonds being active in the poly-
merization), employing 1 as the initiator in chlorobenzene at
À40 °C, the molecular weights of the resulting polymers increased
almost linearly as the increase of the molar ratio of monomer-to-
initiator, (Entries 4, and 10–12, see also Fig. 2), demonstrating
3. Conclusions
In summary, the novel anionic bridged-indenyl rare earth
metal benzyl complexes [{C9H6SiMe2(CH2)2SiMe2C9H6}Ln(CH2C6
H4-p-tBu)2] [Li(THF)4] (Ln = Y (1), Lu (2)) have been successfully syn-
thesized by an acid–base reaction of rare earth metal trisbenzyl
complexes with one equiv. of C9H7SiMe2(CH2)2SiMe2C9H7 in THF
Table 1
Polymerization of MMA Initiated by Bridged-Indenyl Rare Earth Metal Benzyl Complexes 1 and 2.a
CH3
C
H
C
H
CH3
C
H
H
Initiator
C
C
n
n
C
O
O
O
O
CH3
CH3
Temperature (oC)
Time (min)
Convb
%
TOFc
Mn, calc.d  10À4
Mn, obsde  10À4
Mw/Mn
Tacticity (%)f
e
Entry
Ln
[M]/[Ln]
Solvent
mm
rm
rr
1
2
3
4
5
6
7
8
Lu
Y
Lu
Y
Y
Y
Y
Y
Y
Y
500
500
1000
1000
500
500
500
1000
1000
250
THF
THF
chlorobenzene
chlorobenzene
chlorobenzene
toluene
35
35
À40
À40
35
35
35
35
0
À40
À40
À40
À78
180
180
30
1
180
180
180
60
1
1
1
1
1
34
38
9
100
63
69
78
40
56
100
100
100
63
57
63
180
60,000
105
115
130
400
33,600
15,000
30,000
48,000
37,800
0.85
0.95
0.45
5.01
1.58
1.73
1.95
2.01
2.80
1.25
2.50
4.00
3.15
2.10
1.75
7.34
18.23
7.01
5.50
7.35
8.38
11.64
4.45
9.58
14.53
12.79
1.43
1.79
1.42
1.27
1.37
2.05
2.15
1.28
1.29
1.24
1.24
1.26
1.37
28.8
30.0
18.8
30.9
31.5
31.7
40.3
38.5
49.5
chlorobenzene
chlorobenzene
chlorobenzene
chlorobenzene
chlorobenzene
chlorobenzene
9
26.4
32.7
29.6
31.3
44.0
36.0
10
11
12
13
Y
Y
Y
500
800
1000
a
Polymerization conditions: Ln = 9
l
mol, Vsolvent = 1 mL.
Conversion = weight of polymer obtained/weight of monomer used.
TOF = mol of MMA (mol of Ln)À1hÀ1
b
c
d
e
f
.
Mcal = ([MMA]/(2[Ln])) Â 100.12 Â conversion.
Measured by GPC relative to PMMA standards.
Determined by 1H NMR in CDCl3 at 25 °C.

D. Lin et al. / Journal of Organometallic Chemistry 694 (2009) 2976–2980
2979
at room temperature. Both complexes can serve as single-compo-
nent initiator for the polymerization of MMA at a wide range of poly-
merization temperature (from À40 to 35 °C), and 1 showed much
higher activity than 2. The polymerization carried out at À40 °C gave
PMMA with high molecular weight (Mn > 104) and relatively narrow
molecular weight distribution (Mw/Mn < 1.42). When the polymeri-
zation was initiated by 1 in chlorobenzene at À40 °C, the molecular
weights of the resulting polymers increased almost linearly as the
monomer-to-initiator ratio was increased, while the narrow molec-
ular weight distributions remained quite narrow (Mw/Mn = 1.24–
1.27), suggesting the molecular weights controllable.
temperature. After the reaction mixture was stirred at room tem-
perature for 3 h, C9H7SiMe2(CH2)2SiMe2C9H7 (0.37 g, 1.0 mmol) in
20 mL of THF was added slowly. After the reaction mixture was
stirred for 2 hours at room temperature, the volatiles were re-
moved in vacuum. Then the yellow residue was extracted with tol-
uene to remove LiCl by centrifugation. The extract was dried under
reduced pressure, and the resulting residue was dissolved in a mix-
ture solution of toluene/THF in 2:1 volume ratio. Cooling to À30 °C
for several days gave yellow crystals in two crops (0.56 g, 53%
based on ligand). 1H NMR (C6D6/THF-d8, 400 MHz): d 0.53 (s, 6H,
Si(CH3)2), 0.74 (s, 6H, Si(CH3)2), 1.33 (m, 4H, CH2CH2), 1.52 (s,
18H, C(CH3)3), 1.56 (m, 16H, THF-b-CH2), 2.21 (s, 4H, ArCH2), 3.65
(m, 16H, THF-a-CH2), 6.03 (d, 2H, Ar–H), 6.65 (d, 2H, Ar–H),
4. Experimental
7.02–7.26 (m, 10H, Ar–H), 7.47 (d, 2H, Ar–H), 8.08 (d, 2H, Ar–H).
13C NMR (C6D6/THF-d8, 100 MHz): d À0.6, À0.2 (Si(CH3)2), 9.4
(CH2CH2), 25.5 (THF-b-CH2), 31.9 (C(CH3)3), 33.7 (C(CH3)3), 49.9,
4.1. Materials and procedures
50.3 (ArCH2), 67.5 (THF-a-CH2), 101.6, 104.2, 118.9, 119.1, 123.5,
All manipulations were performed under pure argon with rigor-
ous exclusion of air and moisture using standard Schlenk tech-
niques and glove box. Solvents (toluene, hexane, and THF) were
distilled from sodium/benzophenone ketyl, degassed by the
freeze-pump-thaw method, and dried over fresh Na chips in the
glove box. Chlorobenzene and MMA were dried by CaH2, and dis-
tilled before polymerization. Anhydrous LnCl3 were purchased from
STREM. 1-tert-Butyl-4-methylbenzene, n-BuLi (1.6 M solution in
hexane), and 1,2-bis(chlorodimethylsilyl)ethane were purchased
from Alfa, and used as received. Deuterated solvents (THF-d8, Ben-
zene-d6, and CDCl3) were obtained from CIL. LiCH2C6H4-p-tBu was
prepared according to the literature [34].
Samples of organo rare earth metal complexes for NMR spectro-
scopic measurements were prepared in the glove box using J.
Young valve NMR tubes. NMR (1H, 13C) spectra were recorded on
a Bruker AVANCE III spectrometer at 25 °C. Carbon, hydrogen,
and nitrogen analyses were performed by direct combustion on a
Carlo-Erba EA-1110 instrument, quoted data are the average of at
least two independent determinations. X-ray structural determina-
tion was carried out on a Rigaku Mercury diffractometer. FT-IR
spectra were recorded on a Bruker TENSOR 27 spectrometer.
Molecular weight and molecular weight distribution of the poly-
mers were measured by PL GPC 50 at 40 °C using THF as eluent
against PMMA standards.
124.0, 124.4, 124.9, 128.5, 130.3, 132.6, 136.6, 154.4 (aromatic-
C). FT-IR (KBr pellets, cmÀ1): 3064 (m), 2962 (s), 2871 (m), 1601
(w), 1515 (w), 1458 (m), 1407 (w), 1362 (w), 1248 (m), 1132
(m), 1047 (s), 816 (s). Anal. Calc. for C62H90LiO4Si2Y: C, 70.81; H,
8.64. Found: C, 70.78; H, 8.27.
4.4. Synthesis of [{C9H6SiMe2(CH2)2SiMe2C9H6}Lu(CH2C6H4-
p-tBu)2][Li(THF)4] (2)
The synthesis of 2 was carried out in the similar way as that for
1, using LuCl3 (1.12 g, 1.0 mmol), LiCH2C6H4-p-tBu (0.47 g,
3.0 mmol), and C9H7SiMe2(CH2)2SiMe2C9H7 (0.18 g, 0.5 mmol).
Complex 2 was isolated as yellow crystals in two crops (0.34 g,
59% based on ligand). 1H NMR (C6D6/THF-d8, 400 MHz): d 0.15 (s,
6H, Si(CH3)2), 0.44 (s, 6H, Si(CH3)2), 1.09 (m, 4H, CH2CH2), 1.21 (s,
18H, C(CH3)3), 1.36 (m, 16H, THF-b-CH2), 2.01 (s, 4H, ArCH2), 3.38
(m, 16H, THF-a-CH2), 5.55 (d, 2H, Ar–H), 6.25 (d, 2H, Ar–H), 6.64
(d, 4H, Ar–H), 6.77 (t, 2H, Ar–H), 6.85 (m, 4H, Ar–H), 6.92 (d, 4H,
Ar–H), 7.10 (d, 2H, Ar–H), 7.74 (d, 2H, Ar–H). 13C NMR (C6D6/
THF-d8, 100 MHz): d À0.3, 0.0 (Si(CH3)2), 9.6 (CH2CH2), 25.8 (THF-
b-CH2), 32.1 (C(CH3)3), 33.8 (C(CH3)3), 53.8 (ArCH2), 67.8 (THF-a-
CH2), 100.5, 102.9, 118.9, 119.4, 123.8, 124.6, 124.7, 124.9, 128.3,
128.5, 129.2, 130.4, 132.9, 137.3, 155.1(aromatic-C). FT-IR (KBr pel-
lets, cmÀ1): 2961 (s), 2903 (m), 2872 (m), 1601 (w), 1515 (w), 1458
(m), 1407 (w), 1362 (w), 1248 (m), 1132 (m), 1047 (s), 816 (s).
Anal. Calc. for C62H90LiLuO4Si2: C, 65.45; H, 7.99. Found: C, 65.36;
H, 7.85.
4.2. Synthesis of C9H7SiMe2(CH2)2SiMe2C9H7
To a hexane solution (90 mL) of freshly distilled indene (11.6 g,
100 mmol), n-BuLi (1.6 M, 62.5 mL, 100 mmol) in hexane solution
was added slowly at room temperature. After the reaction mixture
was stirred at room temperature for 7 h, 1,2-bis(chlorodimethylsi-
lyl)ethane (10.7 g, 50.0 mmol) in 25 mL of hexane was added drop
wise at room temperature. The resulting reaction mixture was stir-
red for 17 h to give a white slurry. Then, the white precipitate was fil-
tered off, and the clear filtrate was dried in vacuum to afford the title
product as white powder (17.9 g, 96%). 1H NMR (C6D6, 400 MHz) d:
À0.05 (s, 6H, Si(CH3)2), 0.01 (s, 6H, Si(CH3)2), 0.40 (m, 4H, CH2CH2),
3.54 (s, 2H, CH in five-membered ring), 6.63, 7.01, 7.34, 7.38, 7.56,
7.61 (12H, Ar–H). 13C NMR (C6D6, 100 MHz) d: À5.0, À4.6 (Si(CH3)2),
7.1 (CH2CH2), 45.4 (CH in five-membered ring), 121.5, 122.9, 124.1,
125.3, 129.3, 135.6, 144.6, 145.7 (Ar–C). FT-IR (KBr pellets, cmÀ1):
3065 (m), 2958 (m), 2905 (m), 1449 (m), 1409 (m), 1361 (m), 1242
(s), 1134 (m), 1056 (s), 1010 (s), 814 (s), 772 (s). Anal. Calc. for
C24H30Si2: C, 76.94; H, 8.07. Found: C, 76.76; H, 8.16.
4.5. Polymerization of MMA
All polymerization were carried out in a 50 mL Schlenk flask un-
der Ar atmosphere. A typical polymerization reaction for MMA is
given below (Entry 1, Table 1). A 50 mL Schlenk flask equipped
with a magnetic stirring bar was charged with 1 (10 mg, 9 lmol)
and THF (1.0 mL). The flask was kept at 35 °C for 10 min, and then
MMA (0.45 mmol) was added by a syringe. The contents in the
flask were vigorous stirred for 3 h at 35 °C. Then, the polymeriza-
tion was terminated by quenching with excess ethanol containing
5% HCl. The polymeric precipitate was filtered, and dried under
vacuum to constant weight.
4.6. X-ray crystallographic study
Suitable single crystals of 2 were sealed in the thin-walled glass
4.3. Synthesis of [{C9H6SiMe2(CH2)2SiMe2C9H6}
Y(CH2C6H4-p-tBu)2][Li(THF)4] (1)
capillary for structural determination. Intensity data were collected
with a Rigaku Mercury CCD area detector in
x scan mode using Mo
K
a
radiation (k = 0.71070 Å). The diffracted intensities were cor-
To a THF slurry of YCl3 (0.39 g, 2.0 mmol), LiCH2C6H4-p-tBu
rected for Lorentz polarization effects and empirical absorption cor-
(0.93 g, 6 mmol) in 30 mL of THF was added drop wise at room
rections. The structure was solved by direct methods and refined by

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D. Lin et al. / Journal of Organometallic Chemistry 694 (2009) 2976–2980
full-matrix least-squares procedures based on |F|2. All the non-
hydrogen atoms were refined anisotropically. All the hydrogen
atoms were held stationary and included in the structure factor cal-
culation in the final stage of full-matrix least-squares refinement.
The structure was solved and refined using SHELEXL-97 program. Crys-
tal data for 2: C66H98LiLuO5Si2, Mr = 1209.53, crystal size 0.80 Â
0.60 Â 0.20 mm, monoclinic, space group P21/n, a = 11.202(1) Å,
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b = 24.236(3) Å, c = 24.973(3) Å,
a
= 90°, b = 93.778(3)°,
c = 90°,
V = 6765.2(14) Å3, Z = 4, Dcalc = 1.188 g cmÀ3
,
l
= 1.538 mmÀ1
,
F(0 0 0) = 2544, T = 293(2) K, 59,410 collected, 12,337 independent
reflections [max. 2h 6 50.70] and 617 parameters, S = 1.164,
R1 = 0.0744, wR2 = 0.1975 [I > 2r(I)], R1 = 0.1007, wR2 = 0.2290 (all
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Supplementary material
CCDC 709672 contains the supplementary crystallographic
data for complex 2. These data can be obtained free of charge from
The Cambridge Crystallographic Data Centre via www.ccdc.cam.a-
c.uk/data_request/cif.
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Acknowledgements
This work was partly financial supported by the National Natu-
ral Science Foundation of China (20604023), Zhejiang Provincial
Natural Science Foundation (Y406301), Ningbo Municipal Natural
Science Foundation (2008A610056), and Key Laboratory Founda-
tion of Ningbo (2007A22011).
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