Coordination of allenyl/propargyl group to samarium(III): The first crystal structures of η3-allenyl and η1-propargyl lanthanide complexes

Article abstract of DOI:10.1016/S0022-328X(00)00479-4

The synthesis and crystal structures of samarium complexes incorporating bridged Cp′-SiMe₂-allenyl/propargyl ligands [Cp′ = (Me₃Si)₂(C₅H₂)] are described. The reaction of a dilithium salt of [(Me₃Si)₂(C₅H₃)]SiMe ₂CH₂C≡CSiMe₃ (1a) with SmCl₃ yielded an η³-allenyl complex {[(Me₃Si)₂(C₅H₂)]SiMe ₂(η³-C=C=C[H]SiMe₃)}SmCl₃Li ₂(TMEDA)₂ (2a) (TMEDA = N,N,N′,N′-tetramethylethylenediamine). On the other hand, the reaction of a dilithium salt of a Ph₃Si substituted ligand [(Me₃Si)₂(C₅H₃)]SiMe ₂CH₂C≡CSiPh₃ (1b) with SmCl₃ yielded an η¹-propargyl complex {[(Me₃Si)₂(C₅H₂)]SiMe ₂(η¹-CHC≡CSiPh₃)}-Sm(TMEDA)[Cl ₂Li(TMEDA)] (2b). A conversion of bonding mode from η¹-propargyl to η³-allenyl was observed when 2b was treated with (Me₃Si)₃CLi/LiI to give an η³-allenyl complex {[(Me₃Si)₂(C₅H₂)]SiMe ₂(η³-CH=C=CSiPh₃)}SmI₂Li(TMEDA) (3b). The same structural conversion was also observed when 2b was treated with (Me₃Si)₂CHLi to give an anionic ate complex ({[(Me₃Si)₂(C₅H₂)]SiMe ₂(η³-CH=C=CSiPh₃)}SmCl[CH(SiMe ₃)₂])[Li(TMEDA)₂] (4b), which had the η³-allenyl bonding structure. The structures of these four complexes (2a, 2b, 3b, and 4b) were revealed by X-ray crystallography. These are the first examples of the structural characterization of η³-allenyl and η¹-propargyl lanthanide complexes.

Full text of DOI:10.1016/S0022-328X(00)00479-4

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Journal of Organometallic Chemistry 613 (2000) 26–32
Coordination of allenyl/propargyl group to samarium(III): the first
crystal structures of h3-allenyl and h1-propargyl lanthanide
complexes
Eiji Ihara a, Motomi Tanaka a, Hajime Yasuda a,*1, Nobuko Kanehisa b,
Tatsuya Maruo b, Yasushi Kai b,*2
a Department of Applied Chemistry, Faculty of Engineering, Hiroshima Uni6ersity, Higashi-Hiroshima 739-8527, Japan
b Department of Applied Chemistry, Faculty of Engineering, Osaka Uni6ersity, Suita 565-0871, Japan
Received 28 February 2000; received in revised form 1 May 2000; accepted 15 May 2000
Abstract
The synthesis and crystal structures of samarium complexes incorporating bridged Cp%ꢀSiMe2ꢀallenyl/propargyl ligands
[Cp%=(Me3Si)2(C5H2)] are described. The reaction of a dilithium salt of [(Me3Si)2(C5H3)]SiMe2CH2CꢁCSiMe3 (1a) with SmCl3
yielded an h3-allenyl complex {[(Me3Si)2(C5H2)]SiMe2(h3-CꢂCꢂC[H]SiMe3)}SmCl3Li2(TMEDA)2 (2a) (TMEDA=N,N,N%,N%-
tetramethylethylenediamine). On the other hand, the reaction of
a dilithium salt of a Ph3Si substituted ligand
[(Me3Si)2(C5H3)]SiMe2CH2CꢁCSiPh3 (1b) with SmCl3 yielded an h1-propargyl complex {[(Me3Si)2(C5H2)]SiMe2(h1-CHCꢁCSiPh3)}-
Sm(TMEDA)[Cl2Li(TMEDA)] (2b). A conversion of bonding mode from h1-propargyl to h3-allenyl was observed when 2b was
treated with (Me3Si)3CLi/LiI to give an h3-allenyl complex {[(Me3Si)2(C5H2)]SiMe2(h3-CHꢂCꢂCSiPh3)}SmI2Li(TMEDA) (3b).
The same structural conversion was also observed when 2b was treated with (Me3Si)2CHLi to give an anionic ate complex
({[(Me3Si)2(C5H2)]SiMe2(h3-CHꢂCꢂCSiPh3)}SmCl[CH(SiMe3)2])[Li(TMEDA)2] (4b), which had the h3-allenyl bonding structure.
The structures of these four complexes (2a, 2b, 3b, and 4b) were revealed by X-ray crystallography. These are the first examples
of the structural characterization of h3-allenyl and h1-propargyl lanthanide complexes. © 2000 Elsevier Science B.V. All rights
reserved.
Keywords: Samarium; h3-Allenyl; h1-Propargyl; h5-Cyclopentadienyl; Crystal structure
CH2] (TBM=tribenzylidenemethane) [3] are the rare
1. Introduction
examples of structurally characterized h3-allenyl com-
plexes of Group IV elements. Although Teuben re-
ported the synthesis and spectroscopic characterization
of 2-butynyl lanthanide complexes [Cp*2 LnCH2Cꢁ
Much attention has been paid to the chemistry of
transition metal allenyl/propargyl complexes because of
the intriguing structural features and unusual reactivi-
CCH3, Ln=La, Ce] [4], no crystal structure has been
ties of these complexes [1]. However, in contrast to the
reported on lanthanide allenyl/propargyl complexes to
extensive studies on late transition metal allenyl/propar-
date [5]. On the other hand, Takaki and Fujiwara
reported in situ generation of the allenic Sm species and
its use for synthetic reactions [6]. In this article, we
report the syntheses and the first structure analyses of
gyl complexes [1], much less has been reported on early
transition metal complexes of this type. Cp2Zr(CH3)[h3-
C(Ph)ꢂCꢂCH2] [2] and Cp*(TBM)Zr[h3-C(Me)ꢂCꢂ
allenyl/propargyl samarium complexes with two coordi-
nation modes (h3-allenyl and h1-propargyl), which we
discovered in the course of applying our new bridged
Cp%ꢀSiMe2ꢀallenyl/propargyl ligands [Cp%=(Me3Si)2-
(C5H2)] for complexation with lanthanide metals.
1 *Corresponding author. Fax: +81-824-22-7191; e-mail: ya-
suda@ipc.hiroshima-u.ac.jp (H. Yasuda)
2 *Corresponding author. Fax: +81-824-22-7191
0022-328X/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(00)00479-4

E. Ihara et al. / Journal of Organometallic Chemistry 613 (2000) 26–32
27
Scheme 1.
Scheme 2.
ligand 1b having a Ph3Si group as a substituent. Chang-
ing the substituent on the terminal carbon of the al-
lenyl/propargyl group from Me3Si to Ph3Si resulted in a
2. Results and discussion
As bridged Cp%ꢀSiMe2ꢀallenyl/propargyl ligands
[Cp%=(Me3Si)2(C5H2)], we synthesized new compounds
[(Me3Si)2(C5H3)]SiMe2CH2CꢁCSiR3 [1a (R=Me) and
1b (R=Ph)], which had bis-Me3Siꢀcyclopentadiene and
trimethyl- or triphenylsilyl substituted propyne linked
by a Me2Si bridging group. Both ligands 1a and 1b
were obtained by the sequential additions of
(Me3Si)2CpLi and LiCH2CꢁCSiR3 to Me2SiCl2 fol-
lowed by trap-to-trap distillation (Scheme 1). The
NMR spectra indicated that 1a and 1b existed as
mixtures of isomers with respect to the positions of
substituents and/or double bonds on the Cp ring. In
addition, although we describe 1a and 2a as propargyl
compounds for clarity in Scheme 1, the precise struc-
ture of the allenyl/propargyl moiety could not be deter-
mined from the NMR spectra.
The reaction of a dilithium salt of 1a with SmCl3 in
THF at 23°C in the presence of N,N,N%N%-te-
tramethylethylenediamine (TMEDA) yielded a Sm(III)
complex 2a as dark red needle-like crystals (Scheme 2).
Owing to the high solubility of 2a in organic solvents,
the complex was obtained only in trace yield. The
characterization of 2a was carried out by X-ray crystal-
lographic analysis and the ORTEP drawing is shown in
Fig. 1. Although the poor quality of the data does not
allow us to discuss the detailed bond distances and
angles of 2a, the established atom connectivity in Fig. 1
suggests that the three carbon atoms are coordinated to
a Sm center in an h3-fashion along with the coordina-
tion of the h5-cyclopentadienyl ring and three Cl atoms
[7]. However, considering the standard deviations of
C(1)ꢀC(2) and C(2)ꢀC(3) bond lengths in the analysis,
it is not possible to determine which CꢀC bond is
shorter than the other in the C(1)ꢀC(2)ꢀC(3) sequence.
In order to decrease the solubility and improve the
crystallinity of the resulting complexes, we used the
Fig. 1. Molecular structure of 2a.
Fig. 2. Molecular structure of 2b.

28
E. Ihara et al. / Journal of Organometallic Chemistry 613 (2000) 26–32
mode from h1-propargyl to h3-allenyl most probably
originated from the increase in both electronic and
steric coordinative unsaturation on the Sm center,
which would be mainly caused by the removal of the
TMEDA molecule.
The same structural conversion was also observed by
the transformation of 2b to an anionic samarium ate
complex 4b. The reaction of 2b with (Me3Si)2CHLi in
toluene at 23°C resulted in the introduction of the alkyl
group on the Sm center, affording the anionic ate
complex 4b with one of the Cl atoms remaining on Sm
(Scheme 4). By the transformation from 2b to 4b, the
electron density on the Sm center substantially in-
creased as indicated by the presence of an anionic
charge on the Sm in the ate complex 4b. Therefore, the
conversion of the bonding mode from h1-propargyl to
h3-allenyl in this case should arise only from the steric
constraint imparted by the change of the Cl3Li2-
(TMEDA)2 moiety to the Cl[CH(SiMe3)2].
Scheme 3.
drastic change in the coordination mode of the allenyl/
propargyl anion. Fig. 2 shows the crystal structure of
the Sm complex 2b obtained by the reaction of a
dilithium salt of 1b with SmCl3 in the identical reaction
conditions to the synthesis of 2a (Scheme 3). Unfortu-
nately, the quality of the data of the highly air-sensitive
crystals of 2b were not sufficient for a detailed discus-
sion of the structure and only the connectivity of the
atoms can be reliably described [7]. Nevertheless, the
ORTEP drawing in Fig. 2 reveals that the interaction
between the allenyl/propargyl anion and the Sm center
exists only through the SmꢀC(1) s-bond, resulting in an
h1-propargyl coordination. In accord with the h1-
propargyl coordination, both C(2) and C(3) carbons
seem to assume sp-hybridization, forming a linear ar-
rangement with C(1) and Si(2) atoms. It is noteworthy
that in the structure of 2b with the h1-propargyl bond-
ing, the coordinative unsaturation on the highly elec-
trophilic Sm cation is compensated by the direct
coordination of a TMEDA molecule through two ni-
trogen atoms.
The precise structures of the h3-allenyl complexes 3b
and 4b were determined by X-ray diffraction studies.
The molecular structures of 3b and 4b are shown in
Figs. 3 and 4, respectively. Selected bond distances and
bond angles are listed in Tables 1 and 2 and illustrated
in Fig. 5. As shown in Table 2 and Fig. 5, structural
parameters of the h3-allenyl coordinations of C(1),
C(2), and C(3) to Sm in 3b and 4b are very similar
except that the bond distances of Sm to the three
carbons in 4b are slightly longer than those in 3b. The
longer bond lengths in 4b should arise from the pres-
ence of the anionic charge on the Sm center in the
complex, which renders the SmꢀC bonds in 4b weaker
than those bonds in neutral complex 3b. The following
points should be noted as common structural features
of h3-allenyl coordination in 3b and 4b: (i) the bond
distances of SmꢀC(2) and SmꢀC(3) are nearly equal,
A conversion of the bonding mode from h1-propar-
gyl to h3-allenyl was observed by removing the coordi-
nated TMEDA molecule on the Sm center and
exchanging two Cl anions for two I anions in 2b. The
transformation was achieved by the reaction of 2b with
(Me3Si)3CLi/LiI in toluene at 23°C. Removal of the
TMEDA by (Me3Si)3CLi and anion exchange by LiI
resulted in the formation of an h3-allenyl samarium
complex 3b (Scheme 4). The conversion of the bonding
,
and they are about 0.3 A shorter than SmꢀC(1) bonds;
,
(ii) C(2)ꢀC(3) bonds are about 0.1 A shorter than
Scheme 4.

E. Ihara et al. / Journal of Organometallic Chemistry 613 (2000) 26–32
3. Experimental
29
3.1. General considerations
All manipulations were performed on a high-vacuum
line using standard Schlenk techniques under a purified
Ar atmosphere. Solvents were distilled from Na/K alloy/
benzophenone ketyl, except for toluene, which was
distilled from Na/benzophenone ketyl. Me2SiCl2 (Shin-
Etsu), 1-trimethylsilyl-1-propyne (CH3ꢀCꢁCꢀSiMe3,
Tokyo Kasei), and N,N,N%,N%-tetramethylethylenedi-
amine (TMEDA, Tokyo Kasei) were stored with CaH2
and used without distillation. Ph3SiCl (Shin-Etsu), n-
Table 1
Crystal data for 3b and 4b
Fig. 3. Molecular structure of 3b.
3b
4b
Formula
C40H58SmSi4N2- C55H98N4SmSi6Li-
LiI2
ClO0.5
Formula weight
Crystal system
Space group
1090.40
Triclinic
1184.67
Triclinic
(
(
P1
P1
,
a (A)
13.584(3)
17.532(3)
11.050(2)
90.71(2)
99.61(2)
108.52(1)
2454.2(9)
2
15.211(6)
19.811(5)
11.881(5)
104.50(3)
92.03(4)
79.19(3)
3404(2)
2
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
3
,
V (A )
Z
Dcalc (g cm−3
F(000)
)
1.475
1078
25.81
1.163
1260
10.44
Fig. 4. Molecular structure of the anion 4b.
v (Mo–Ka) (cm−1
)
Number of measured
reflections
Number of observed
reflections
11748
16217
C(1)ꢀC(2) bonds; (iii) the bond angles C(1)ꢀC(2)ꢀC(3)
are ca. 163° and they are 17° smaller than the ideal value
of sp hybridization on C(2) carbons (180°); (iv)
Si(1)ꢀC(1)ꢀC(2) angles are close to 120°, which is the
ideal value of sp2 hybridization on C(1) carbons, and
C(2)ꢀC(3)ꢀSi(2) angles are about 16° larger than the ideal
value. On the basis of these observations, we can
reasonably conclude that C(2)ꢀC(3) bonds are stronger
than C(1)ꢀC(2) bonds and a H atom attaches to the C(1)
carbon in both complexes, although we could not locate
the position of the H atom near C(1), C(2), or C(3) from
the electron density in the diffraction studies of 3b and
4b. These are the first examples of complete structural
characterization of the bonding interaction between
lanthanide metals and allenyl/propargyl anions.
In conclusion, although we have not yet elucidated the
behavior of 2a, 2b, 3b, and 4b in solution [8], we have
for the first time succeeded in revealing the solid state
bonding structures of two types (h3-allenyl and h1-
propargyl) on lanthanide allenyl/propargyl complexes.
These findings will extend the chemistry of transition
metal allenyl/propargyl complexes to Group III ele-
ments.
6205
8584
(Fo$3.0|(Fo))
a
R
(Rw) b
0.060 (0.061)
1.50
0.058 (0.059)
1.36
GOF
a R=SꢀꢀFoꢀ−ꢀFcꢀꢀ/SꢀFoꢀ.
b Rw=(S w(ꢀFoꢀ−ꢀFoꢀ)2/S wꢀFoꢀ2)1/2; w=1/|2(Fo).
Table 2
Selected bond lengths (A) and angles (°) of 3b and 4b
,
Compound
3b
4b
Bond lengths
SmꢀC(1)
SmꢀC(2)
SmꢀC(3)
C(1)ꢀC(2)
C(2)ꢀC(3)
2.827(10)
2.551(9)
2.58(1)
1.35(1)
1.25(1)
2.962(7)
2.662(7)
2.657(7)
1.368(10)
1.255(9)
Bond angles
Si(1)ꢀC(1)ꢀC(2)
C(1)ꢀC(2)ꢀC(3)
C(2)ꢀC(3)ꢀSi(2)
120.4(7)
163.5(10)
136.7(9)
118.4(6)
162.8(8)
136.3(6)

30
E. Ihara et al. / Journal of Organometallic Chemistry 613 (2000) 26–32
Fig. 5. Selected bond lengths and angles of 3b and 4b.
BuLi (1.6 M solution in hexane, Kanto Chemicals), and
1-propynylmagnesium bromide (CH3ꢀCꢁCMgBr, 0.5 M
solution in THF, Aldrich) were used as received.
Me3SiCpH was prepared by the reaction of CpNa with
Me3SiCl. (Me3Si)2CpH was prepared by the reaction of
Me3SiCpNa with Me3SiCl. SmCl3 was prepared by the
reaction of Sm2O3 with HCl in the presence of excess
NH4Cl, followed by removal of excess NH4Cl by subli-
mation at 360° under vacuum. (Me3Si)3CH [9] and
(Me3Si)2CHLi [10] were prepared following the reported
procedures. 1H-NMR spectra were recorded on a JEOL
JNM-LA 400 spectrometer (395.75 MHz) in sealed
tubes at ambient probe temperature. Chemical shifts
were reported versus SiMe4 and were determined by
reference to the residual solvent peaks. New ligands 1a
and 1b cannot be characterized by NMR spectroscopy
because they exist as mixtures of isomers both in terms
of the positions of substituents and CꢀC double bonds
on the Cp ring. Complexometric metal analyses were
conducted by the method reported by Atwood and
Evans [11].
solution of (Me3Si)2(C5H3)SiMe2Cl held at 0°C and the
mixture was stirred at 23°C for 12 h. The reaction
mixture was poured into a saturated aqueous solution of
NaHCO3 (500 ml) and the organic layer was separated.
The aqueous layer was extracted with hexane (2×100
ml) and the combined organic layer was dried over
Na2SO4. After the volatiles were removed by flash
distillation, 1a was obtained by trap-to-trap distillation
(120°C, 1 mmHg) as a yellow oil (11.7 g, 30.9 mmol,
78.3%).
3.3. Preparation of 1-triphenylsilyl-1-propyne
A solution of Ph3SiCl (2.46 g, 8.33 mmol) in THF (50
ml) was cooled to 0°C. CH3ꢀCꢁCMgBr (0.50 M solution
in THF, 16.0 ml, 8.00 mmol) was added to the solution
dropwise at 0°C and the mixture was stirred and gradu-
ally warmed to 23°C over 20 h. The mixture was poured
into a saturated aqueous solution of NaHCO3 and the
organic layer was separated. The aqueous layer was
extracted with hexane and the combined organic layer
was dried over Na2SO4. Removal of the volatiles af-
forded 1-triphenylsilyl-1-propyne as a white solid (1.60
3.2. Preparation of
[(Me3Si )2(C5H3)]SiMe2CH2CꢁCSiMe (1a)
1
g, 5.35 mmol, 66.9%). H-NMR (CDCl3): l 7.34–7.68
(m, 15H, PhꢀH), 2.05 (s, 3H, CH3).
A solution of (Me3Si)2CpH (10.0 ml, 40.4 mmol) in
THF (60 ml) was cooled to 0°C. n-BuLi (1.63 M
solution in hexane, 24.5 ml, 39.9 mmol) was added to
the solution dropwise and the mixture was stirred at 0°C
for 5 h. Me2SiCl2 (4.8 ml, 40 mmol) was added to the
mixture at 0°C and the resulting mixture was stirred at
3.4. Preparation of
[(Me3Si )2(C5H3)]SiMe2CH2CꢁCSiPh (1b)
The procedure described above for 1a was employed
using (Me3Si)2CpH (6.00 ml, 24.3 mmol) in THF (90
ml), n-BuLi (1.59 M solution in hexane, 15.0 ml, 23.9
mmol), and Me2SiCl2 (2.9 ml, 24 mmol) to generate
(Me3Si)2CpSiMe2Cl, and CH3ꢀCꢁCꢀSiPh3 (7.19 g, 24.0
mmol), TMEDA (4.0 ml, 27 mmol) in THF (90 ml), and
n-BuLi (1.59 M solution in hexane, 15.0 ml, 23.9 mmol)
to generate LiCH2ꢀCꢁCꢀSiPh3. 1b was obtained by
trap-to-trap distillation (230°C, 1 mmHg) as a yellow oil
(10.1 g, 17.8 mmol, 74.6%).
23°C for
3 h to give a solution of (Me3Si)2-
(C5H3)SiMe2Cl. A solution of CH3ꢀCꢁCꢀSiMe3 (6.0 ml,
41 mmol) and TMEDA (6.4 ml, 42.4 mmol) in THF (60
ml) was cooled to 0°C. n-BuLi (1.63 M solution in
hexane, 24.5 ml, 39.9 mmol) was added to the solution
dropwise and the mixture was stirred at 23°C for 2 h to
generate
a
solution of LiCH2ꢀCꢁCꢀSiMe3. The
LiCH2ꢀCꢁCꢀSiMe3 solution was added dropwise to the

E. Ihara et al. / Journal of Organometallic Chemistry 613 (2000) 26–32
31
3.5. Preparation of {[(Me3Si )2(C5H2)]SiMe2(p3-
CꢂCꢂC[H]SiMe3)}SmCl3Li2(TMEDA)2 (2a)
3.7. Preparation of (Me3Si )3CI
A solution of (Me3Si)3CH (46.3 g, 199 mmol) in
THF (300 ml) was cooled to 0°C. MeLi (1.0 M in
Et2O, 200 ml, 200 mmol) was added dropwise to the
solution at 0°C and the mixture was refluxed for 12
h. After the mixture was cooled to −78°C, a solu-
tion of 1,2-diiodoethane (58 g, 200 mmol) in THF (60
ml) was added. After the mixture was stirred for 1 h
at −78°C, it was gradually warmed to 23°C with
stirring. The reaction mixture was washed with a
aqueous Na2S2O3 solution and the separated organic
layer was dried over Na2SO4. After the volatiles were
removed under reduced pressure, the residual solid
was dissolved in hexane and an unsolved solid was
removed by filtration. Removal of hexane afforded
(Me3Si)3CI as a pale yellow powder. (59.0 g, 0.165
mol, 83% yield). 1H-NMR (CDCl3): l 0.24 (s, 27H,
Me3Si).
A solution of 1a (3.59 g, 9.46 mmol) and TMEDA
(3.0 ml, 20 mmol) in THF (60 ml) was cooled to 0°C.
n-BuLi (1.66 M solution in hexane, 11.4 ml, 18.9
mmol) was added dropwise to the solution at 0°C
and the mixture was stirred at 23°C for 5 h. The
mixture was added to a suspension of SmCl3 (2.43 g,
9.45 mmol) in THF (75 ml) at 23°C and the mixture
was stirred at 23°C for 12 h. The volatiles were re-
moved under vacuum and the residual solid was dis-
solved into toluene (90 ml). After a small amount of
an insoluble solid was removed by centrifugation, tol-
uene was removed under vacuum. Recrystallization of
the residual solid from hexane afforded red needle-
like crystals of 2a, which were suitable for X-ray
crystallographic analyses. Because of the high solubil-
ity of 2a, 2a was obtained only in trace yield and
improving the yield has been difficult so far. 1H-
NMR spectrum of the crystals of 2a indicated that
the complex existed as a mixture of isomers. 1H-
NMR (the main isomer, C6D6): l 14.27 (s, 1H, CpꢀH
or Me3Si[H]CꢂCꢂC), 7.10 (s, 1H, CpꢀH or Me3Si-
[H]CꢂCꢂC), 3.84 (s, 1H, CpꢀH or Me3Si[H]CꢂCꢂC),
2.27 (s, 24H, CH3N), 2.07 (s, 8H, CH2N), 1.79 (s, 3H,
Me2Si), 1.42 (s, 3H, Me2Si), 0.24 (s, 9H, Me3SiCp or
Me3Si[H]CꢂCꢂC), −0.13 (s, 9H, Me3SiCp or Me3Si-
[H]CꢂCꢂC), −0.95 (s, 9H, Me3SiCp or Me3Si-
[H]CꢂCꢂC). Anal. Calc. for C31H68Cl3Li2N4Si4Sm:
Sm, 17.09. Found: Sm, 16.94%.
3.8. Preparation of Et2O solution of (Me3Si )3CLi/LiI
A suspension of Li powder (3.14 g, 453 mmol) in
Et2O (210 ml) was cooled to −78°C. A solution of
(Me3Si)3CI (65.0 g, 181 mmol) in Et2O (210 ml) was
added dropwise to the suspension at −78°C and the
reaction mixture was stirred and gradually warmed to
23°C over 4 h. Removal of a part of LiI, which
appeared as a solid, and excess Li powder by cen-
trifugation and filtration through glass wool afforded
an Et2O solution of (Me3Si)3CLi/LiI, whose concen-
tration of (Me3Si)3CLi was determined by titration
with HCl–NaOH (yield of (Me3Si)3CLi was quantita-
tive).
3.6. Preparation of {[(Me3Si )2(C5H2)]SiMe2-
(p1-CHCꢁCSiPh3)}Sm(TMEDA)[Cl2Li(TMEDA)2] (2b)
3.9. Preparation of {[(Me3Si )2(C5H2)]SiMe2-
(p3-CHꢂCꢂCSiPh3)}SmI2Li(TMEDA)2 (3b)
A solution of 1b (3.86 g, 6.83 mmol) and TMEDA
(2.1 ml, 14 mmol) in THF (60 ml) was cooled to 0°C.
n-BuLi (1.59 M solution in hexane, 8.50 ml, 13.5
mmol) was added to the solution dropwise at 0°C
and the mixture was stirred at 23°C for 7 h. The
mixture was added to a suspension of SmCl3 (1.73 g,
6.75 mmol) in THF (60 ml) at 23°C and was then
stirred at 23°C for 12 h. The volatiles were removed
under vacuum and the residual solid was dissolved in
toluene (80 ml). After a small amount of an insoluble
solid was removed by centrifugation, toluene was re-
moved under vacuum. Recrystallization of the resid-
ual solid from diethyl ether afforded red needle-like
crystals of 2b (2.54 g, 2.48 mmol, 36.8%). The 1H-
NMR spectrum of the crystals of 2a was too compli-
cated to assign because the complex existed as a
mixture of isomers. Anal. Calc. for C46H74Cl2LiN4-
Si4Sm: Sm, 14.69. Found: Sm, 14.42%.
A solution of 2b (0.65 g, 0.64 mmol) in toluene (45
ml) was cooled to 0°C. (Me3Si)3CLi/LiI ((Me3Si)3CLi
=0.69 M in Et2O, 1.1 ml, 0.76 mmol) was added
dropwise to the solution at 0°C and the mixture was
stirred at 23°C for 48 h. After an in-
soluble solid was removed by centrifugation, volatiles
were removed under vacuum. Recrystallization of the
residual solid from Et2O afforded orange needle-
like crystals of 3b, which were suitable for X-ray
crystallographic analyses. The crystals of 3b were ob-
tained only in trace yield because of the high solubil-
ity of the complex. The 1H-NMR spectrum of the
crystals of 3b was too complicated to assign because
the complex existed as a mixture of isomers. Anal.
Calc. for C40H58I2LiN2Si4Sm: Sm, 13.79. Found: Sm,
13.54%.

32
E. Ihara et al. / Journal of Organometallic Chemistry 613 (2000) 26–32
3.10. Preparation of ({[(Me3Si )2(C5H2)]SiMe2(p3-CHꢂ
CꢂCSiPh3)}SmCl[CH(SiMe3)2])[Li(TMEDA)2] (4b)
deposit@ccdc.cam.ac.uk or www: http://www.ccdc.cam.
ac.uk).
A solution of 2b (1.72 g, 1.68 mmol) in toluene (45
ml) was cooled to 0°C. (Me3Si)2CHLi (0.96 M in Et2O,
2.1 ml, 2.02 mmol) was added dropwise to the solution
at 0°C and the mixture was stirred at 23°C for 48 h.
After an insoluble solid was removed by centrifugation,
volatiles were removed under vacuum. The residual
solid was washed with hexane (60 ml) to remove unre-
acted (Me3Si)2CHLi. Recrystallization of the hexane
insoluble solid from Et2O afforded yellow needle-like
crystals of 4b (1.02 g, 0.89 mmol, 52.9%). The 1H-NMR
spectrum of the crystals of 4b indicated that the com-
plex existed as a mixture of isomers. 1H-NMR (the
Acknowledgements
This work was supported by a Grants-in-aid for
Scientific Research on Priority Areas (No. 283, ‘Innova-
tive Synthetic Reactions’) from the Monbusho.
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main isomer, C6D6):
l
9.78 (s, 1H, CpꢀH or
Ph3SiCꢂCꢂCH), 8.21 (d, 6H, 3JHH=7.1 Hz, o-Ph), 7.87
3
(s, 1H, CpꢀH or Ph3SiCꢂCꢂCH), 7.36 (t, 6H, JHH
=
3
7.1 Hz, m-Ph), 7.27 (t, 3H, JHH=7.5 Hz, p-Ph), 1.88
(s, 8H, CH2N), 1.84 (s, 24H, CH3N), 0.95 (s, 9H,
Me3Si), 0.71 (s, 9H, Me3Si), 0.46 (s, 3H, Me2Si), 0.10 (s,
3H, Me2Si), −0.14 (s, 9H, Me3Si), −0.40 (s, 9H,
Me3Si). One of the CpꢀH or Ph3SiCꢂCꢂCH signals and
a CH(SiMe3)2 signal were obscured by the other reso-
nances. Anal. Calc. for C53H93ClLiN4Si6Sm: Sm, 13.10.
Found: Sm, 12.97%.
4. Supplementary material
Crystal data and data collection parameters are con-
tained in Table 1. Crystallographic data for the struc-
tural analyses have been deposited with the Cambridge
Crystallographic Data Center, CCDC nos. 140444 (2a),
140445 (2b), 140446 (3b), and 140447 (4b). Copies of
this information may be obtained free of charge from:
The Director, CCDC, 12 Union Road, Cambridge,
CB2 1EZ UK (Fax: +44-1223-336-033; e-mail:
[11] J.L. Atwood, W.E. Hunter, A.L. Wayda, W.J. Evans, Inorg.
Chem. 20 (1981) 4115.
.