Catalytic activity of allyl-, azaallyl- and diaza-pentadienyllanthanide complexes for polymerization of methyl methacrylate

Article abstract of DOI:10.1016/S0022-328X(98)00977-2

A variety of allylic, aza-allylic and 1,5-diazapentadienyllanthanide compounds were synthesized and their polymerization catalysis toward methyl methacrylate were examined. Divalent Sm[1,3-bis(trimethylsilyl)propenyl]₂(THF)₂ 1 and Sm(1,3-diphenylpropenyl)₂(THF)₂ 2 were synthesized by the reaction of potassium 1,3-bis(trimethylsilyl)propenide or potassium 1,3-diphenylpropenide with SmI₂. The aza-allyllanthanide compound was synthesized by the reaction of 2-pyridylbenzyllithium with SmCl₃ followed by the reaction with LiCH(SiMe₃)₂ to give (2-pyridylbenzyl)₂SmCH(SiMe₃)₂ 3. 1,5-Diazapentadienyllanthanide was prepared by the reaction of K[(C₅H₄N)₂CPh] with YbBr₂ to give Yb[(C₅H₄N)₂CPh]₂(THF)₂ 4, which crystalizes monoclinic, space group C2/C (No. 15), with a=35.19(1), b=13.613(3), c=26.552(7) A, β=133.77(1)°, and Z=8. Preparations of divalent samarium and ytterbium complexes with bis(2-pyridylphenylmethyl)dimethylsilane ligand (6 and 7) were carried out by the reaction of dipotassium salt of bis(2-pyridylphenylmethyl)dimethylsilane with SmI₂ or YbBr₂. By using the resulting compounds 1, 2, 3, 4, 6 and 7 as initiator, we have examined their catalytic activities for the polymerization of methyl methacrylate and found that compounds 6 and 7 are effective to give high molecular weight isotactic polymers.

Full text of DOI:10.1016/S0022-328X(98)00977-2

Journal of Organometallic Chemistry 574 (1999) 40–49
Catalytic activity of allyl-, azaallyl- and diaza-pentadienyllanthanide
complexes for polymerization of methyl methacrylateꢀ
Eiji Ihara a, Kouji Koyama a, Hajime Yasuda a,*, Nobuko Kanehisa b, Yasushi Kai b,1
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, Yamadaoka 565-0871, Japan
Received 3 June 1998; received in revised form 4 July 1998
Abstract
A variety of allylic, aza-allylic and 1,5-diazapentadienyllanthanide compounds were synthesized and their polymerization
catalysis toward methyl methacrylate were examined. Divalent Sm[1,3-bis(trimethylsilyl)propenyl]2(THF)2 1 and Sm(1,3-diphenyl-
propenyl)2(THF)2 2 were synthesized by the reaction of potassium 1,3-bis(trimethylsilyl)propenide or potassium 1,3-diphenyl-
propenide with SmI2. The aza-allyllanthanide compound was synthesized by the reaction of 2-pyridylbenzyllithium with SmCl3
followed by the reaction with LiCH(SiMe3)2 to give (2-pyridylbenzyl)2SmCH(SiMe3)2 3. 1,5-Diazapentadienyllanthanide was
prepared by the reaction of K[(C5H4N)2CPh] with YbBr2 to give Yb[(C5H4N)2CPh]2(THF)2 4, which crystalizes monoclinic, space
˚
group C2/C (No. 15), with a=35.19(1), b=13.613(3), c=26.552(7) A, i=133.77(1)°, and Z=8. Preparations of divalent
samarium and ytterbium complexes with bis(2-pyridylphenylmethyl)dimethylsilane ligand (6 and 7) were carried out by the
reaction of dipotassium salt of bis(2-pyridylphenylmethyl)dimethylsilane with SmI2 or YbBr2. By using the resulting compounds
1, 2, 3, 4, 6 and 7 as initiator, we have examined their catalytic activities for the polymerization of methyl methacrylate and found
that compounds 6 and 7 are effective to give high molecular weight isotactic polymers. © 1999 Elsevier Science S.A. All rights
reserved.
Keywords: Complexes; Polymerization catalysis; Methyl methacrylate; Allylanthanide; Azaallylanthanide
1. Introduction
rare earth metal complex toward MMA [3]. Although
simple metallocene type allyl compounds have been
synthesized, their catalytic activites have not yet been
reported [4,5]. On the other hand, only a limited num-
ber of non-metallocene type rare earth metal com-
pounds has been reported as polymerization initiator.
For example, Ln(allyl)4Li (Ln=Ce, Nd, Sm, Gd, Dy)
is found to serve as initiator for the polymerization of
butadiene to give trans-rich 1,4-poly(butadiene) [6].
We have reported the living polymerization of alkyl
methacrylates [1] and alkyl acrylates [2] by the metal-
locene type organic rare earth metal complexes, which
produce high molecular weight polymers (Mn\
100 000) with very narrow molecular weight distribu-
tion (Mw/MnB1.05). Especially noteworthy is the
highly stereospecific polymerization of methyl
methacrylate (MMA) at low temperature to give 96%
syndiotacticity. More recently, Novak reported high
catalytic activity of metallocene type bifunctional allyl
Preparation
of
aza-allylytterbium,
bis(SiMe3N-
CPhCHSiMe3)Yb [7] and amidinate compound
bis(SiMe3N–CPh–NSiMe3)YR, [8] has been reported
but their catalytic activity was not known. This paper
describes the synthesis of non-metallocene type novel
bis-allyl-, bis-azaallyl- and bis-diazapentadienyllan-
thanide compounds and their catalytic activities for the
polymerization of MMA.
ꢀ Dedicated to the late Professor Rokurou Ogawara as a tribute to
his memory.
* Corresponding author. Fax: +81-82-4227191.
1 Also corresponding author.
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(98)00977-2

E. Ihara et al. / Journal of Organometallic Chemistry 574 (1999) 40–49
41
Fig. 1. 1H-NMR spectrum of [1,3-(Me3Si)2prpenyl]2Sm(TMEDA).
Scheme 1.
2. Results and discussion
and 2.9 ppm, allyl 3.1 and 6.9 ppm). Thus, two allyl
moieties exsist in the same magnetic circumstances to
indicate the presence of high symmetrical structure.
Synthesis of divalent (1,3-diphenylally)2Sm was ex-
plored using potassium 1,3-diphenylpropenide and
SmI2 (Scheme 2). Although 1H-NMR spectrum (see
Section 3) shows the formation of the desired com-
pound, bis(1,3-diphenylprpenyl)2Sm(THF)2 2, in quan-
titative yield, the reaction gave the product as an oily
compound presumably due to their large coordinative
unsaturation.
2.1. Synthesis of bis(allyl)lanthanide compound
1,3-Bis(trimethylsilyl)allylsamarium compound was
prepared by the reaction of 1,3-bis(trimethylsilyl)allyl
potassium with SmI2 in the presence of N,N,N%,N%-te-
tramethylethylenediamine (TMEDA) as highly air sen-
1
sitive pale-brown crystals in 36% yield. The H-NMR
spectrum indicates the presence of one equimolar
amount of TMEDA (1.7 and 1.9 ppm) and allyl groups
(d, 2.9 ppm and q, 7.2 ppm) (Fig. 1). However, the
resulting compound shows only a little catalytic activity
for the polymerization of MMA presumably due to
the strong donation of TMEDA molecule to Sm atom.
Therefore, we have examined the synthesis of cor-
responding THF adduct as shown in Scheme 1.
The desired compound bis[1,3-bis(trimethylsilyl)-
propenyl]Sm(THF)2 1 was obtained as a red oil in 23%
yield. More pure compound [1,3-(trimethylsi-
lyl)propenyl)]2Sm(DME)2 was obtained as a pale-
brown solid in 49% yield when 1,2-dimethoxyethane
(DME) was used in place of THF but recrystallization
form THF/hexane did not give crystals suitable for
X-ray diffraction (1H-NMR; SiMe3 0.4 ppm, DME 2.7
2.2. Preparation of bis(2-pyridylbenzyl)SmCH(SiMe3)2
In order to obtain crystalline allyl samarium com-
pound, we have used the aza-allyl ligand in place of the
conventional allylic ligands, because the donation of a
nitrogen atom to samarium will enhance the strong
bond-formation. Furthermore, trivalent complexes
should lower the coordinative unsaturation. Therefore,
synthesis of the trivalent aza-allylsamarium was exam-
ined here (Scheme 3). The 2:1 reaction of 2-pyridylben-
zyllithium with anhydrous SmCl3 gave desired
(C5H4N–CHPh)2SmCl2Li(THF)2 as evidenced by the
1H-NMR spectrum (see Section 3). Then a bulky alkyl-

42
E. Ihara et al. / Journal of Organometallic Chemistry 574 (1999) 40–49
Scheme 2.
Scheme 4.
2.3. Preparation of bis[(2-pyridyl)2CPh]Yb(THF)2 4
The introduction of one nitrogen atom to the allyl
ligand does not successfully bring about the formation
of good crystals. Therefore, we introduced two nitrogen
atoms into the pentadienyl ligand at the 1- and 5-posi-
tions. The resulting compound is considered as a kind
of open metallocene compound. Although the reaction
of SmI2 with K[(C5H4N)2CPh] gave an oily compound
containing some impurities, the reaction of YbBr2 gave
the desired complex, bis[(2-pyridyl)2CPh]Yb(THF)2 4,
as red crystals in 86% yield based on the potassium
compound (Scheme 4). The structure was analyzed by
1H-NMR (C6D6) as shown in Fig. 3. Finally the X-ray
analysis was performed on this compound (ORTEP
drawing is shown in Fig. 4). The crystal data and
experimental conditions are summarized in Table 1,
and selected bond distances and angles are given in
Scheme 3.
lithum, bis(trimethylsilyl)-methyllithium, was added to
this THF solution to afford (C5H4N–CHPh)2SmCH–
(SiMe3)2 3 in 75% yield as red crystals. Its H-NMR
1
spectrum
is
given
in
Fig.
2.
(C5H4N–
CHPh)2SmCl2Li(THF)2 is insoluble in hexane but
(C5H4N–CHPh)2SmCH–(SiMe3)2 becomes very solu-
ble. The molecular weight determination obtained
cryoscopically in benzene agreed to their monomeric
form (see Section 3). However, we have not succeeded
in determining the structure of 3 by X-ray analysis.
Fig. 2. 1H-NMR spectrum of (2-pyridylbenzyl)2SmCH(SiMe3)2 3.

E. Ihara et al. / Journal of Organometallic Chemistry 574 (1999) 40–49
43
Fig. 3. 1H-NMR spectrum of [(2-Pyr)2CPh]2Yb(THF)2 4.
Fig. 4. ORTEP drawing of [(2-pyr)2Cph]2Yb(THF)2 4.
2.4. Preparation of bis[(2-pyridyl)2CPh]Yb(vMe)2AlMe2
5
Table 2. The Yb compound is hexa-coordinated with
four nitrogen atoms and two oxygen atoms. The av-
erage bond distances of the Yb–N atoms (2.436 A)
˚
Since divalent bis[(2-pyridyl)2CPh]Yb(THF)2 was ob-
tained in pure form, we have examined the synthesis of
corresponding trivalent complex by reacting with excess
AlR3. In fact, the addition of excess AlMe3 brings
about the formation of bis[(2-pyridyl)2CPh]Yb(v-
Me)2AlMe2 5 in high yield (85%) as orange single
crystals. The 1H-NMR spectrum (Fig. 5) shows the
single resonance of AlMe4 group at room temperature
and we could not find any coordinated solvent such as
THF. The measurement of the molecular weight
cryoscopically in benzene indicates that the complex
are greater than the YbꢀN bonds of the divalent
˚
Yb[NR–CPh–CHR]2 (2.33 A) [7]. Therefore, the
YbꢀN bonding in the present complex is rather loose
as compared with Yb[NR–CPh–CHR]2. However,
the YbꢀN bonding between the Yb atom and the
coordinated pyridine in (C8H8)Yb(C5H5N)3 is much
˚
greater (2.56–2.59 A) than the present compound [9].
˚
The YbꢀO bond distances (2.456 A) are nearly the
˚
same as that (2.41 A) of Yb(C5Me5)2(THF)(C7H8)0.5
[10].

44
E. Ihara et al. / Journal of Organometallic Chemistry 574 (1999) 40–49
exists as monomeric form (calc. 722.8, observed 735).
Addition of excess THF or ether, however, did not
remove the coordinated AlMe3 to form bis[(2-pyridyl)2
CPh]YbMe(donor) and even the use of a strong donor,
pyridine, is ineffective to remove the coordinated
AlMe3. Thus, the nature of the present complex differs
greatly from Cp2Yb(v-Me)2AlMe2 [11], Cp2Y(v-
Me)2AlMe2[12] and (C5Me5)2Sm(v-Me)2AlMe2 [13].
2.5. Preparation of di6alent samarium and ytterbium
complexes with bis(2-pyridylphenylmethyl)dimethylsilane
ligand (6 and 7)
We have synthesized also silylene bridged aza-allyl
Table 1
Crystal data and experimental factors for [(2-pyr)2Cph]2Yb(THF)2
4
Experimental formula
YbC50N4H58O2
Formula weight
Crystal color
Crystal system
Space group
920.7
Fig. 5. 1H-NMR spectrum of [(2-pyr)2Cph]2Yb(v-Me)2AlMe2 5.
colorless
monoclinic
C2/c (no. 15)
35.19(1)
13.613(3)
26.552(7)
133.77(1)
9185(4)
8
1.331
3776
20.77
0.3×0.3×0.25
3B2qB50
(0.68+0.35 tan q)°
10.0
10029
10018
˚
a (A)
˚
b (A)
˚
c (A)
i (°)
V (A )
3
˚
Z
Dcalc. (g cm−3
F(000)
)
v (Mo–Kh) (cm−1
Crystal dimension
2q range
)
Scan width 2q
Scheme 5.
Scan speed (° min−l
Reflection observed
Unique reflection
Radiation damage
)
compounds of samarium and ytterbium in 45 and 52%
yields, respectively, following the Scheme 5. The ligand
was prepared by the reaction of 2-benzylpyridine with
butyllithium followed by Me2SiCl2 in 84% yield. The
desired samarium 6 and ytterbium 7 compounds were
prepared by the conventional method as red crystals.
The structure of 6 was confirmed by 1H-NMR spectrum
(Fig. 6) and molecular weight measurement (calc. 677.8,
observed 691).
No
5896
650
2.97
0.058
0.059
No. of observation (I\3.00|(I))
No. of variables
GOF
R
Rw
Table 2
Selected bond distances (A) and bond angles (°) for complex 4
˚
˚
Bond lengths (A)
Yb–N(1)
Yb–N(2)
Yb–N(3)
Yb–N(4)
Yb–O(1)
Yb–O(2)
2.434(7)
2.419(8)
2.428(8)
2.425(8)
2.456(7)
2.456(8)
N(1)–C(15)
N(1)–C(11)
C(1)–C(11)
C(1)–C(21)
N(2)–C(21)
N(2)–C(25)
1.36(1)
1.36(1)
1.41(1)
1.43(1)
1.39(1)
1.35(1)
2.6. Polymerization of methyl methacrylate with 1, 2,
3, 4, 6 and 7
All the compounds synthesized here actually exhibit
no catalytic activity towards the polymerization of
ethylene and 1-hexene. However, these complexes serve
as good initiators for the polymerization of MMA
(Table 3). The allyl complexes 1 and 2 showed relatively
low catalytic activity and these catalysts gave a low
molecular weight polymers with rather wide molecular
weight distributions. Isotactivity is also low. In contrast
Bond angles (°)
O(1)–Yb–O(2)
N(1)–Yb–N(2)
N(3)–Yb–N(4)
N(1)–Yb–N(3)
N(1)–Yb–O(1)
78.0(2)
73.4(3)
73.0(3)
99.4(3)
167.9(2)
N(2)–Yb–N(4)
N(1)–Yb–N(4)
C(31)–C(2)–C(41)
C(11)–C(1)–C(21)
165.3(3)
96.6(3)
127.7(9)
128.7(9)

E. Ihara et al. / Journal of Organometallic Chemistry 574 (1999) 40–49
45
Fig. 6. 1H-NMR spectrum of ytterbium complex with bis(2-pyridylphenylmethyl)-dimethylsilane ligand 6.
Table 3
Polymerization of methyl methacrylate with Sm and Yb complexes
Initiator
Temperature (°C)
Polymerization time (h)
Yield (%)
Mn (10−4
)
Mw/Mn Isotacticity (%)
Ratio (%)
1
2
3
4
6
r.t.
0
r.t.
0
5
5
20
20
3
6.5
0.89
1.36
2.94
3.80
200
80.7
5.34
2.56
66.0
5.51
250
9.56
256
9.56
155
8.7
255
6.98
4.65
0.37
4.51
3.31
3.81
1.02
1.02
3.00
1.57
2.50
1.43
2.55
1.26
1.87
1.72
2.01
1.93
2.45
2.18
42.6
45.3
49.1
46.3
64.3
68.2
72.5
12.3
21.6
5.9
34.1
6.3
0
−78
−78
3
2
99.3
26.6
73.4
46.2
53.8
31.3
68.7
16.4
83.6
49.8
50.2
37.2
62.8
20.3
79.7
r.t.
0
2
2
2
2
2
2
39.2
89.3
72.2
46.2
81.9
54.3
76.5
82.8
82.3
81.9
88.5
78.1
−78
r.t.
0
7
16.8
260
18.7
−78
to these initiators, aza-allyl lanthanide complexes
showed high catalytic activities. For example, 4 gives
the polymer in quantitative yield at −78°C and this
initiator gives a high molecular weight poly(MMA)
with a very narrow molecular weight distribution. Iso-
tacticity is also high. Although high molecular weight
monodisperse syndiotactic poly(MMA) is available by
the use of the Ln(C5Me5)2R initiator [1], the corre-
sponding high molecular weight isotactic polymer has
not yet been obtained so far. Fig. 7 shows the plots of
Mn versus yield of polymers obtained by 4. This result
indicates the living polymerization for both high and
low molecular weight polymers. Only low molecular
weight isotactic poly(MMA) is available by using the
RMgX initiator [14]. Therefore, the present technique is
superior to other conventional catalytic systems to ob-
tain high molecular weight isotactic polymers, although
the resulting polymer shows a bi-modal pattern in GPC
measurement. Catalytic activities for 6 and 7 are lower
than that of 4. The complex 4 also catalyzes the poly-

46
E. Ihara et al. / Journal of Organometallic Chemistry 574 (1999) 40–49
3.2. Preparation of di6alent 1,3-bis(trimethylsilyl)
propenylsamarium compound 1
1,3-Bis(trimethylsiyl)propene was prepared by the
following procedure. 3-Trimethylsilylpropene (20
mmol, 2.93 ml) was added dropwise to a stirred mixture
of N,N,N%,N%-tetramethylethylenediamine (TMEDA)
(23 mmol, 3.5 ml) and butyllithium (22.5 mmol) under
argon at 5°C and the stirring was continued for 3 h.
Chlorotrimethylsilane (20 mmol, 2.6 ml) was added
dropwise at −5°C to this solution and the mixture was
stirred for 1 h. Then the mixture was poured into
HClaq. (20 ml, 1 M) and extracted with hexane (100 ml).
The extract was distilled to give the desired product as
an oil (66–77°C/22 mmHg) in 78% yield. 1H-
NMR(CDCl3) l 6.02 (1H, dt, –CHꢁCH–CH2), 5.42
(1H, d, –CHꢁCHCH2), 1.62(2H, –CHꢁCHCH2), 0.05
(9H, s, TMS), 0.01 (9H, TMS). To a 300 ml round-bot-
tomed flask equipped with a three way stopcock a
mixture of 1,3-bis(trimethylsislyl)propene (40 mmol, 9.3
ml), KOtBu (40 mmol, 2.3 g) and THF (150 ml) was
placed. Butyllithium (40 mmmol) was added to this
mixture and the solution was stirred for 3 h at −78°C
to give potassium 1,3-bis(trimethylsilyl)propenide. On
the other hand, Sm metal (10 mmol, 1.5 g), THF (80
ml) and 1,2-diiodoethane (10 mmol, 1.3 ml) was placed
in 500 ml round-bottomed flask. After stirring the
Fig. 7. Plots of Mn versus yield of polymers obtained by complex 4,
high molecular weight polymer ꢁ, low molecular weight polymer ꢂ.
merization of o-caprolactone and hexyl isocyanate
(Table 4).
3. Experimental
3.1. General
mixture for
3
h, potassium 1,3-bis(trimethylsi-
lyl)propenide (30 mmol, 6.7 g) in THF solution (50 ml)
was added dropwise to the THF solution (50 ml) of the
resulting SmI2 (15 mmol, 6.1 g) at room temperature.
The solution was stirred overnight and evaporated to
dryness. Then the residue was extracted with toluene.
After the toluene was removed by vacuum distillation,
the residual solid was recrystallized from hexane to give
divalent Sm[1,3-bis(trimethylsiyl)propenyl]2(THF)2 1 in
All the manipulations were carried out by using the
standard Schlenk technique under an argon atmo-
sphere. Toluene and THF were dried over calcium
hydride and then over sodium benzophenone ketyl, and
finally these were distilled just before use. NMR spectra
were recorded on a JEOL JNM-LA400 and a Bruker
AM-X400wb instruments. Chemical shifts were cali-
brated using benzene (7.21 ppm), chloroform (7.26
ppm) and toluene (2.09 ppm). The X-ray diffraction
data were collected on a Rigaku AFC5R diffaractome-
ter using a suitable crystal sealed in a thin-walled glass
capillary tube under argon. Number average molecular
weights and molecular weight distributions of resulting
polymers were determined by gel-permeation chro-
matography on a Tosoh SC-8910 high speed liquid
chromatograph equipped with a differential refractome-
ter using column TSK gel G1000, G2000, G3000 and
G4000 in CHCl3 at 40°C.
1
23% yield (2.1 g). H-NMR (C6D6) l 6.43 (2H, CH–
CH–CH), 3.58 (8H, bs, CH2O of THF), 3.20 (4H, d,
CH–CH–CH). 1.39 (8H, bs, CH2 of THF), 0.44 (9H, s,
TMS), 0.19 (9H, s, TMS), 0.03 (18H, s, TMS).
3.3. Preparation of di6alent
1,3-diphenylpropenylsamarium compound 2
Benzaldehyde (189 mmol, 20 g) was condensed with
acetophenone (189 mmol, 22.6 g) in alkaline aqueous
Table 4
Polymerization of other monomers using complex 4
Monomers
Temperature (°C)
Time (h)
Yield (%)
Mn (10−4
)
Mw/Mn
m-Caprolactone
Hexylisocyanate
25
0
0
1
1
2
2
96.9
90.9
34.2
0
13.1
12.6
36.6
1.97
1.85
3.87
25

E. Ihara et al. / Journal of Organometallic Chemistry 574 (1999) 40–49
47
Table 5
yield 80%, m.p. 55.5–56°C). A solution of trans-chal-
cone (60 mmol, 12.8 g) in dry THF (25 ml) was added
dropwise to an ice-cold stirred solution of LiAlH4 (40
mmol, 1.5 g) in dry THF (75 ml) under argon and
stirring was continued for 1 h at room temperature.
After decomposing the mixture with 2N H2SO4, THF
was distilled out and the product was extracted with
ether (150 ml) to give 1,3-diphenylpropan-1-ol (12.1 g)
in 95% yield. 1,3-Diphenylpropane-1-ol (25 mmol, 5.30
g) was refluxed with acetic anhydride (40.7 mmol, 4.1 g)
in pyridine (10 ml) for 1 h, and the mixture was poured
into 1N HCl solution (150 ml). The product was ex-
tracted with ether and the extract was washed with 1N
HCl solution, sodium carbonate solution, and evapo-
rated to give 1,3-diphenyl-2-propyl acetate (6.3 g) in
90% yield. 1,3-Diphenyl-2-propene was prepared by the
pyrolysis of 1,3-diphenyl-2-propenyl acetate (20 mmol,
5 g) in a kuegelroll. The total pyrolysis time is 30 min.
Column chromatography of the crude product gave
Final atomic coordinates and equivalent isotropic temperature factors
for non-hydrogen atoms in [(2-pyr)2CHPh]2Yb(THF)2
4
2
˚
Atom
x
y
z
Beq (A )
Yb
0.19206(2)
0.2104(3)
0.1034(3)
0.1549(3)
0.1874(3)
0.2839(3)
0.2069(3)
0.1171(4)
0.3010(4)
0.1249(3)
0.1014(4)
0.1102(4)
0.1423(4)
0.1624(4)
0.16479(3)
0.3244(5)
0.2351(6)
0.0194(6)
0.1995(6)
0.1158(6)
0.24112(2)
0.2974(4)
0.1679(4)
0.1673(4)
0.1476(4)
0.3283(4)
0.3367(4)
0.0560(5)
0.4347(5)
0.0975(4)
0.0668(6)
0.1060(6)
0.1771(5)
0.2041(5)
0.0777(5)
0.0285(6)
0.0496(7)
0.1195(6)
0.1651(6)
0.4000(5)
0.4374(6)
0.4055(7)
0.3329(6)
0.2978(6)
0.4059(5)
0.4451(6)
0.4211(6)
0.3518(7)
0.3152(6)
3.798(8)
4.9(2)
6.0(2)
3.7(2)
4.1(2)
4.0(2)
4.2(2)
4.0(2)
4.3(2)
3.7(2)
4.6(2)
5.1(3)
4.5(2)
4.4(2)
4.0(2)
5.3(3)
6.2(3)
5.2(3)
4.4(2)
3.8(2)
4.6(3)
5.0(3)
5.3(3)
4.5(3)
3.6(2)
5.3(3)
5.8(3)
6.3(3)
5.0(3)
4.3(2)
5.9(3)
7.4(4)
7.2(4)
6.8(4)
5.0(3)
5.1(3)
6.7(4)
9.2(6)
11.0(6)
9.8(6)
7.2(4)
7.0(5)
14(1)
O(1)
O(2)
N(1)
N(2)
N(3)
N(4)
C(1)
C(2)
C(11)
C(12)
C(13)
C(14)
C(15)
−0.0913(6)
0.0874(7)
0.1227(7)
0.0096(7)
−0.0845(8)
−0.1625(9)
−0.1508(8)
−0.0609(8)
0.1773(7)
0.2480(8)
0.332(1)
C(21) −0.1458(4)
C(22)
C(23)
C(24)
C(25)
C(31)
C(32)
C(33)
C(34)
C(35)
C(41)
C(42)
C(43)
C(44)
C(45)
C(51)
C(52)
C(53)
0.1333(5)
0.1609(5)
0.2039(4)
0.2151(4)
0.3181(4)
0.3708(5)
0.3879(4)
0.3523(5)
0.3019(4)
0.2493(4)
0.2365(5)
0.1879(5)
0.1472(5)
0.1593(5)
0.0745(4)
0.0852(5)
0.0465(7)
1
0.3511(8)
0.2829(8)
0.1075(7)
0.0806(8)
0.0624(9)
0.0692(9)
0.0956(8)
0.1180(7)
0.1386(9)
0.1308(10)
0.098(1)
0.0812(9)
0.0708(7)
0.049(1)
0.035(1)
0.042(1)
pure 1,3-diphenyl-2-propene (1.59 g) H-NMR (CDCl3)
l 7.39–7.22 (10H, aromatic, Ph×2), 6.47 (1H, d,
CH=CHCH2), 6.38 (1H, d, CH=CHCH2), 3.57 (2H,
d, CH=CHCH2). To a 300 ml round-bottomed flask
equipped with a three way stopcock 1,3-diphenyl-2-
propene (40 mmol, 9.7 ml), KOtBu (40 mmol, 2.2 g)
and THF (150 ml) were placed. Butyllithium (40 mmol)
was added to this solution and the mixture was stirred
for 3 h at −78°C to give potassium 1,3-diphenyl-
propenide, which was then added dropwise to the solu-
tion of SmI2 (20 mmol, 8.1 g) in THF (150 ml) at room
temperature. After stirring the mixture overnight, THF
was distilled out and the residue was extracted with
toluene. Recrystallization from hexane gave bis(1,3-
diphenylpropenyl)Sm(THF)2 2 as an orange solid in
−0.0222(5)
−0.0617(6)
−0.1328(7)
−0.1653(7)
−0.1295(7)
0.0585(5)
0.5119(5)
0.5376(7)
0.609(1)
C(54) −0.0048(6)
C(55) −0.0185(6)
0.063(1)
C(56)
C(61)
C(62)
C(63)
C(64)
C(65)
C(66)
C(71)
C(72)
C(73)
C(74)
C(81)
C(82)
C(83)
C(84)
0.0218(4)
0.3442(4)
0.3771(5)
0.4174(6)
0.4240(7)
0.3929(7)
0.3533(6)
0.1861(7)
0.221(1)
0.0777(9)
0.1405(9)
0.222(1)
0.242(1)
0.174(2)
0.094(2)
0.076(1)
0.359(1)
0.423(3)
0.441(2)
0.376(1)
0.324(1)
0.318(3)
0.253(2)
0.192(2)
1
78% yield (10.2 g). H-NMR (C6D6) l 7.32–7.56 (20H,
m, Ph), 6.42 (4H, d, CH), 3.65 (8H, bs, THF), 3.33 (4H,
d, CH), 1.45 (8H, bs, THF).
0.6532(9)
0.6307(8)
0.5600(7)
0.320(1)
0.376(2)
0.383(1)
0.3340(8)
0.1293(9)
0.063(2)
0.079(2)
0.141(2)
3.4. Preparation of bis(2-pyridylbenzyl)SmCH(SiMe3)2
3
0.265(1)
9.9(6)
6.0(4)
7.6(4)
12.6(9)
11.7(8)
12.1(7)
To a 100 ml round-bottomed flask equipped with a
three way stopcock 2-benzylpyridine (30 mmol, 4.8 ml)
and THF (30 ml) were placed. Butyllithium (30 mmol)
was added to this solution and the mixture was stirred
for 3 h at −78–0°C to give 2-pyridylbenzyllithium,
C5H5NCHPhLi, in 80% yield. A THF solution of 2-
pyridylbenzyllithium (20 mmol, 3.5 g) was added to
SmCl3 (10 mmol, 2.6 g) in THF (30 ml) and the mixture
was stirred overnight. After the evaporation of the
solution, the residue was extracted with toluene. The
toluene was evaporated and the residue was recrystal-
lized from THF/hexane (1:1) to give bis(2-pyridylben-
zyl)SmCl2Li(THF)2 in 57% yield (4.0 g). 1H-NMR
(CDCl3) l 8.72 (2H, d, 4-position of Py), 8.48 (2H, bs,
6-position of Py), 7.54 (2H, t, 5-position of Py), 7.12
0.2584(6)
0.0914(6)
0.035(1)
0.0114(9)
0.0567(7)
ethanol [NaOH (237 mmo, 19.5 g), ethanol (54 ml) and
water (85 ml)]. After stirring the mixture for 3 h, the
solution was neutralized with HCldil. solution and then
the ethanol was distilled under reduced pressure. The
residue was extracted further with ether and the extract
was washed with water, dried and evaporated in vacuo.
Recrystallization of the solid from aqueous ethanol
gave a light yellow crystals (trans-chalcone) (31.4 g,

48
E. Ihara et al. / Journal of Organometallic Chemistry 574 (1999) 40–49
(2H, d, p-Ph), 6.77 (2H, t, 3-position of Py), 6.39 (2H,
s, CH), 5.80 (4H, t, m-Ph), 4.92 (4H, bs, o-Ph), 3.80
(8H, bs, THF), 1.48 (8H, bs, THF). Molecular weight
measurement: cryoscopically in benzene, observed 756;
calc. 704.89.
tion of Py), 8.11 (4H, bs, 4-position of Py), 7.49 (4H,
bs, 5-position of Py), 7.28 (2H, bs, p-Ph), 6.82 (4H,
3-position of Py), 6.63 (4H, d, m-Ph), 6.03 (4H, o-Ph),
3.38 (8H, bs, THF), 1.21 (8H, bs, THF).
An ether solution of 0.56 M LiCH(SiMe3)2 (5.6
mmol) was added to a toluene solution (60 ml) of
bis(2-pyridylbenzyl)SmCl2Li(THF)2 (5.6 mmol, 4.0 g)
at 0°C and the mixture was stirred for 24 h at room
temperature. After the removal of toluene, the residue
was extracted with hexane (100 ml). Centrifugation
followed by recrystallization from hexane gave a red
powder of bis(2-pyridylbenzyl)SmCH(SiMe3)2 in 75%
3.6. Preparation of bis[(2-pyridyl)2CPh]Yb(v-Me)2
AlMe2 5
To a stirred solution of the ytterbium(II) species
[(C4H4N)2CPh]2Yb(THF)2 (5 mmol, 4.0 g) in 100 ml
toluene, five equivalents of AlMe3 (25 mmol, 2.3 ml)
were added. During stirring the mixture for 24 h,
orange precipitates were generated in an orange solu-
tion. Then the mixture was washed with 200 ml of
1
yield (2.6 g) H-NMR (CDCl3) l 12.1 (2H, bs, 6-posi-
tion of Py), 9.33 (2H, d, 4-position of Py), 7.79 (2H, t,
5-position of Py), 7.40 (2H, d, p-Ph), 6.70 (3H, t,
3-position of Py), 6.10 (4H, t, m-Ph), 5.40 (4H, bs,
o-Ph), 4.66 (2H, s, CH), 0.35 (1H, s, CH(SiMe3)2), 0.10
(9H, SiMe3). Molecular weight measurement: observed
650; calc. 646.10.
hexane
to
separate
the
resulting
[(2-
pyridyl)2CPh]2Yb(v-Me)2AlMe2 from AlMe3. The
residue was dissolved into toluene (100 ml). Centrifuga-
tion followed by recrystallization from hexane/toluene
gave orange crystals of [(2-pyridyl)2CPh]2Yb(m-
1
Me)2AlMe2 in 85% yield (3.1 g). H-NMR (CDCl3) l
7.47 (4H, d, 6-position of Py), 7.33 (4H, t, 4-position of
Py), 7.21 (2H, t, p-Ph), 7.17 (4H, d, 5-position of Py),
6.48 (4H, t, 3-position), 6.37 (4H, d, m-Ph), 5.87 (4H, t,
o-Ph), −0.20 (12H, s, Me).
3.5. Preparation of bis[(2-pyridyl)2CPh]Yb(THF)2 4
To a round-bottomed flask equipped with a three
way stopcock 2-benzylpyridine (0.4 mol, 64.2 g) and
ether (120 ml) were placed. Butyllithium (0.44 mol) was
added to this solution with a dropping funnel and the
mixture was stirred for 3 h at −78–0°C to give the
aza-allyl salt. Bromopyridine (0.5 mol, 48.1 ml) was
dropwise added at 0°C and the mixture was stirred
overnight and then poured into excess NaHCO3 solu-
tion, which was then extracted with ether (3×100 ml).
The yellow oil thus obtained was washed with hexane
and dried to yield yellow solid of dipyridylphenyl-
methane in 46% yield (45.2 g). 1H-NMR (CDCl3) l
8.66 (2H, Py), 7.72 (2H, Py), 7.43–7.31 (7H, Py and
Ph), 7.19 (2H, Py), 5.94 (1H, CH). To a 100 ml
round-bottomed flask dipyridylphenylmethane (14
mmol, 4.0 g) and THF (50 ml) were placed. Butyl-
lithium (14 mmol) was added to this solution and the
mixture was stirred for 3 h at 0°C–room temperature
to give Li[(C5H4N)2CPh](THF)2. Then KOtBu (14
mmol, 0.8 g) dissolved in THF was added and the
mixture was stirred overnight. THF was removed by
distillation and the residue was washed with hexane
(3×30 ml) to remove LiOtBu. THF solution of potas-
sium salt K[(C5H4N)2CPh] (8 mmol, 2.3 g) was added
dropwise to the solution of YbBr2 (4 mmol, 1.2 g) in
THF (80 ml) at 0°C. The solution was stirred at room
temperature overnight and THF was removed under
reduced pressure. After extracting the residue with
toluene (50 ml), the solution was evaporated to dryness
and the residue was recrystallized from THF/hexane
3.7. Preparation of di6alent samarium and ytterbium
complexes with the bis(2-pyridylphenylmethyl)-
dimethylsilane ligand (6 and 7)
To a 500 ml round-bottomed flask equipped with a
three way stopcock 2-benzylpyridine (0.2 mol, 32.1 g)
and THF (200 ml) were placed. Butyllithium (0.2 mol)
was added to this solution at 0°C and the mixture was
stirred for 3 h to give the aza-allyllithium salt. Di-
cholordimethylsilane (0.1 mol, 12.1 ml) was added
dropwise to this solution and the mixture was stirred
for 5 h. The reaction mixture was poured into NaHCO3
aqueous solution, which was then extracted with ether
(100 ml). The extract was washed with methanol to
yield
a
white
solid
of
bis(2-pyridylphenyl-
1
methyl)dimethysilane in 84% yield (33.1 g). H-NMR
(CDCl3) l 8.66 (2H, m, Py), 7.72 (2H, m, Py), 7.43–
7.31 (7H, m, Py and Ph), 7.19 (2H, Py), 5.94 (1H, CH)
0.05 (CH, SiMe). Butyllithium (20 mmol) was added
dropwise to
a THF solution (50 ml) of bis(2-
pyridylphenylmethyl)dimethylsilane (10 mmol, 3.9 g)
and the solution was stirred for 3 h at −78–0°C to
give the lithium salt of bis(2-pyridylphenyl-
methyl)dimethylsilane. Then KOtBu (20 mmol) in THF
was added at 30°C under reduced pressure and the
residue was washed with hexane to remove LiOtBu.
The THF solution of the dipotassium salt of bis(2-
pyridylphenylmethyl)dimethylsilane (8 mmol, 3.7 g) was
added to the solution of SmI2 (8 mmol, 32.4 g) in THF
(100 ml) at −78°C and the mixture was stirred
overnight. THF was removed by distillation and the
(1:1)
to
give
the
ytterbium(II)
complex,
[C5H4N)2CPh]2Yb(THF)2, as dark red crystals in 86%
1
yield (2.8 g). H-NMR (CDCl3) l 9.65 (4H, bs, 6-posi-

E. Ihara et al. / Journal of Organometallic Chemistry 574 (1999) 40–49
49
residue was extracted with toluene (120 ml). The
toluene soluble part was recrystallized from THF/hex-
ane (1:1) to give [(Py–CPh)2SiMe2]SM(THF)2 6 as red
crystas in 45% yield (4.2 g). In the case of the ytterbium
complex 7, YbBr2 was used instead of SmI2.
isotropically by the full-matrix least-squares method,
while the hydrogen atoms were fixed at their standard
geometries and were not refined. All the calculations
were performed using the teXsan crystallographic soft-
ware package.2 The final atomic coordinates and equiv-
alent isotropic temperature factors for non-hydrogen
atoms for complex 4 are listed in Table 5.
3.8. Typical procedure for the polymerization of methyl
methacrylate
Monomer (typically 100–200 equivalents to initiator)
was injected via a syringe into a solution of an initiator
(typically 0.04 mmol) in toluene (10 ml) with vigorous
stirring at the fixed temperature (−78°C–room tem-
perature). After stirring for a fixed time (2–20 h), the
reaction mixture was poured into excess MeOH in
order to quench the living polymer end. The precipi-
tated polymer was collected and dried under vacuum.
Measurement of tacticity for poly(MMA) was per-
formed by 270 MHz 1H-NMR in CDCl3 (Me peak; mm
1.43, mr 1.28, rr 1.14 ppm) [15] or by 62.9 MHz
13C-NMR in CDCl3 (mmmm 176.2, mmmr 176.1, rrrrr
177.9, mrrrr 177.6 ppm) [16]. The isotacticity, 88.7%,
(mm%) observed corresponds to a 72% mmmm value.
References
[1] (a) H. Yasuda, H. Yamamoto, K. Yokota, S. Miyake, A.
Nakamura, J. Am. Chem. Soc. 114 (1992) 4908. (b) H. Yasuda,
H. Yamamoto, M. Yamashita, K. Yokota, A. Nakamura, S.
Miyake, Y. Kai, N. Kanehisa, Macromolecules 22 (1993) 7134.
(c) H. Yasuda, E. Ihara, Adv. Polym. Sci. 133 (1997) 53.
[2] E. Ihara, M. Morimoto, H. Yasuda, Macromolecules 28 (1995)
7886.
[3] L.S. Boffa, B.M. Novak, Macromolecules 27 (1994) 6993.
[4] G.A. Molander, J.O. Hoberg, J. Am. Chem. Soc. 114 (1992)
3123.
[5] W.J. Evans, T.A. Uribarri, J.W. Ziller, J. Am. Chem. Soc. 112
(1990) 2314.
[6] A. Mazzel, in: T.J. Marks, R.D. Fischer (Eds.), Organometallics
of the f-Element, Ch. 12, Reidel, Dordrecht, 1979.
[7] P.B. Hitchcock, S.A. Holmes, M.F. Lappert, S. Tian, J. Chem.
Soc., Chem. Commun. (1994) 2691.
3.9. X-ray structure analysis of bis[(2-pyridyl)2CPh]Yb-
(THF)2 4
[8] R. Duchateau, C.T. van Wee, A. Meetsma, P.T. van Duijnen,
J.H. Teuben, Organometallics 15 (1996) 2279.
[9] A.L. Wayda, I. Mukerji, J.L. Dye, R.D. Rogers, Organometal-
lics 6 (1987) 1328.
The integrated intensity data were measured on a
Rigaku AFC5R diffractometer with graphite-
monochromated Mo–Kh (u=0.7106 A) radiation. As
[10] T.D. Tilley, R.A. Anderson, B. Spencer, H. Ruben, A. Zalkin,
D.H. Templeton, Inorg. Chem. 19 (1980) 2999.
[11] J. Holton, M.F. Lappert, D.G.H. Ballard, R. Pearce, J.L. At-
wood, W.E. Hunter, J. Chem. Soc. Dalton (1979) 45.
[12] J. Holton, M.F. Lappert, D.G.H. Ballard, R. Pearce, J.L. At-
wood, W.E. Hunter, J. Chem. Soc. Dalton (1979) 54.
[13] W.J. Evans, L.R. Chamberlain, T.A. Uribarri, J.W. Ziller, J.
Am. Chem. Soc. 110 (1988) 6423.
[14] K. Hatada, K. Ute, K. Tanaka, Y. Okamoto, T. Kitayama,
Polym. J. 18 (1986) 1037.
[15] K. Hatada, T. Kitamura, Y. Terawaki, R. Chujo, Polym. J. 19
(1987) 1121.
˚
the complex 4 is very air-sensitive, the crystal was
sealed in a thin-walled glass capillary tube under argon
atmosphere. The X-ray data were collected at room
temperature using ꢀ–2q scan technique to a maximum
2q value of 50°. The data were corrected for conven-
tional absorption, Lorentz and polarization effects. The
crystal structure was solved by the heavy-atom method.
Yb was found in Patterson map. Successive Fourier
synthesis clearly revealed the remaining non hydrogen
atoms. The non-hydrogen atoms were refined an-
[16] G. Moad, D.H. Solmon, T.H. Supering, S.R. Jones, R.I. Willing,
Aust. J. Chem. 39 (1986) 43.
2 teXsan: crystal structure analysis package, Molecular Structure
Corporation (1985 and 1992).