Synthesis of 2,6-dialkoxylphenyllanthanoid complexes and their polymerization catalysis

Article abstract of DOI:10.1016/S0022-328X(98)00783-9

The 1:1-2:1 reaction of [2,6-(ⁱPrO)₂C₆H₃]Li with anhydrous SmCl₃ in THF gave [2,6-(ⁱPrO)₂C₆H₃]₃ Sm 1 exclusively, while the 3:1 reaction gave [2,6-(ⁱPrO)₂C₆H₃]₄SmLi 2 as major product, which crystallizes in the monoclinic space group C2/c(No. 15) with a=47.52(1) A, b=11.680(9) A, c=18.862(9) A, β=112.19(3)°, V=9694(8) A³, Z=8, R=0.077 and R_w=0.074. In a similar manner, [2,6-(ⁱPrO)₂C₆H₃]₃La was obtained by reacting with LaCl₃(THF)₂. The 2:1 reaction of [2,6-(ⁱPrO)₂C₆H₃]Li with YbCl₃ gave [2,6-(ⁱPrO)₂C₆H₃]₂YbCl, which produces [2,6-(ⁱPrO)₂C₆H₃] ₂Yb[CH(SiMe₃)₂]₂Li 4 by reaction with (SiMe₃)₂CHLi. Polymerizations of ε-caprolactone and alkyl isocyanates were examined using the resulting complexes.

Full text of DOI:10.1016/S0022-328X(98)00783-9

Journal of Organometallic Chemistry 569 (1998) 147–157
Synthesis of 2,6-dialkoxylphenyllanthanoid complexes and their
polymerization catalysis1
Eiji Ihara a, Yoshifumi Adachi a, Hajime Yasuda a,*, Hiroshi Hashimoto b, Nobuko Kanehisa b,
Yasushi Kai b
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 31 March 1998
Abstract
The 1:1–2:1 reaction of [2,6-(iPrO)2C6H3]Li with anhydrous SmCl3 in THF gave [2,6-(iPrO)2C6H3]3 Sm 1 exclusively, while the
3:1 reaction gave [2,6-(iPrO)2C6H3]4SmLi 2 as major product, which crystallizes in the monoclinic space group C2/c(No. 15) with
3
˚
˚
˚
˚
a=47.52(1) A, b=11.680(9) A, c=18.862(9) A, i=112.19(3)°, V=9694(8) A , Z=8, R=0.077 and Rw=0.074. In a similar
manner, [2,6-(iPrO)2C6H3]3La was obtained by reacting with LaCl3(THF)2. The 2:1 reaction of [2,6-(iPrO)2C6H3]Li with YbCl3
gave [2,6-(iPrO)2C6H3]2YbCl, which produces [2,6-(iPrO)2C6H3]2Yb[CH(SiMe3)2]2Li 4 by reaction with (SiMe3)2CHLi. Polymeriza-
tions of ‡-caprolactone and alkyl isocyanates were examined using the resulting complexes. © 1998 Elsevier Science S.A. All rights
reserved.
Keywords: Tri(phenyl)samarium; Polymerization catalyst; Methyl methacrylate; ‡-Caprolactone; Hexyl isocyanate; Butyl iso-
cyanate; Rare earth metal compound
p-HC6F4; Ln=Sm, Eu, Yb) [5–7] and (benzene)tricar-
bonylchromium derivatives [(OC)3CrPh]2Ln(THF)n
1. Introduction
(Ln=Sm, Eu, Yb; n=1–2) [8]. Diphenylmercury was
found to be unreactive toward free Yb [6], while slow
interaction was observed with the amalgamated metal
[8], and violent reaction has been reported for ytter-
bium metal activated with CH2I2 [9]. Phenylytterbium
species are formed in these processes in 35–75% yields
and identified in situ by reactions with H2O, Ph3SnCl,
and 9-fluorenone to be Ph2Yb [8,9]. More recently,
synthesis of Ph3Ln (Ln=Er, Tm) in the presence of
catalytic amounts of LnI3 was reported [10]. (Naph-
tharene)Yb compound C10H8Yb(THF)2 was reported
to react readily with Ph2Hg to form the binuclear
complex (THF)Ph2Yb(v-Ph)3Yb(THF)3 [11]. Among
(aryl)3Ln compounds, X-ray structural data are avail-
able only for (o-Me2NCH2C6H4)3Lu [11] and the binu-
clear derivative (THF)Ph2Yb(v-Ph)3Yb(THF)3, con-
sisted of Ph2YbII(THF) and Ph3YbIII(THF)3 [11].
Reported synthetic pathways to homoleptic lan-
thanoid aryls of R2Ln and R3Ln type are not of general
utility for the entire lanthanoid series. Thus, the reac-
tion of PhLi with LnCl3 yields Ph3Sc and Ph3Y,
whereas the anionic (Ph4Ln)Li complexes were isolated
in the case of La and Pr [1]. Chelating (aminotolyl)-
lithium reagents allowed the synthesis of |-aryls (o-
Me2NCH2C6H4)3Ln of Sc, Y, Pr, Yb, and Lu [2–4].
However no characterizable products have been iso-
lated in the case of Pr, Nd, Sm and Tb [3]. Transmeta-
lation reactions of R2Hg with metallic lanthanoids have
been successfully attempted for preparation of
polyfluorophenyl complexes R2Ln (R=C6F5, o-HC6F4,
* Corresponding author. Fax: +81 824 227191
1 Dedicated to Professor Akira Nakamura on the occasion of his
retirement.
0022-328X/98/$ - see front matter © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00783-9

148
E. Ihara et al. / Journal of Organometallic Chemistry 569 (1998) 147–157
Scheme 1.
Scheme 2.
The reactions of PhLnI (Ln=Yb, Sm, Eu) with
PhFC=CF2 [12], PhCH=CHC(O)Ph [13], and CF2=
CF2 [14] were reported. Fine review articles concerning
cyclopentadienyl group-free organolanthanide chem-
istry should be consulted on the recent development in
this area [15]. This paper describes the synthesis of
(2,6-dialkoxyphenyl)3Ln (Ln=Sm, La, Y) and (2,6-di-
single crystals of [2,6-(iPrO)2C6H3]3Sm 1 in 70–80%
yield based on [2,6-(iPrO)2C6H3]Li (Scheme 1). Sm3+
˚
exhibits intermediate ionic radius (0.96 A) among the
rare earth metal. The resulting compound is insoluble
in hexane but soluble in benzene, toluene and THF,
revealing the monomeric nature in benzene (observed
Mw=740 determined by cryoscopic method in benzene,
calc. 729.4). We have failed the X-ray diffraction analy-
sis of this compound, because of the presence of high
symmetric structure (X-ray analysis is unsuited for the
molecules with very high symmetry). 1H-NMR spec-
trum of this compound showed the presence of the Me
signal of the isopropyl group (a,a%) at 1.47 and 0.86
ppm to indicate that these isopropyl groups are in
different environments (Fig. 1). The structure shown in
Fig. 1 is the most conceivable. On the other hand,
protons at meta and para position showed a doublet at
5.42 ppm and a triplet at 6.58 ppm, respectively. In
alkoxyphenyl)4LnLi
by
reaction
of
(2,6-di-
alkoxyphenyl)lithium with LnCl3 and the polymeriz-
ation of several monomers using these compounds.
2. Results and discussion
2.1. Synthesis of [2,6-(iPrO)2C6H3]3Sm and
[2,6-(iPrO)2C6H3]4SmLi
The 2:1 or 1:1 reaction of [2,6-(iPrO)2C6H3]Li with
anhydrous SmCl3 in THF gave air-sensitive yellow
Fig. 1. 1H NMR spectrum of [2,6-(iPrO)2C6H3]3Sm 1 in C6D6.

E. Ihara et al. / Journal of Organometallic Chemistry 569 (1998) 147–157
149
Fig. 2. ORTEP drawing of [2,6-(iPrO)2C6H3]4SmLi 2
(iPrO)2C6H3]4SmLi 2 was obtained exclusively as air-
sensitive pale-yellow crystals (Scheme 2). The crystal
structure was finally determined by X-ray diffraction
studies and its ORTEP drawing is illustrated in Fig. 2.
The Sm molecule is 9-coordinated with four bidentate
isopropoxyphenyl ligands and one Li atom. Three iso-
propoxy groups are co-ordinated to the Li atom and
this left one isopropoxy group, which is free from
co-ordination.
order to estimate the strength of the co-ordination of
isopropoxy group to the Sm atom, variable temperature
NMR spectra were recorded. As a result, two Me
groups coalesced at 90°C and a broad singlet peak was
observed at 1.67 ppm, at that temperature the isopro-
poxy groups are magnetically equivalent with each
other. When the reaction was carried out in the pres-
ence of tetramethylethylenediamine (TMEDA), [2,6-
(iPrO)2C6H3]3Sm was again obtained without
co-ordination of TMEDA. Thus neutral triphenylsa-
marium was obtained as monomeric form by the assis-
tance of alkoxy ligand. Similar assistance was already
reported in the case of the phenyl group bearing the
alkylamino assistant group [16,17]. The substitution of
alkyl group at positions 2 and 6 by phenyl group is also
effective to bring about the formation of monomeric
species such as Lu(2,6-Me2C6H3)4Li(THF)4 [18], al-
though no substitution of the phenyl group very often
resulted in the formation of oligomeric or polymeric
species [19,20]. Exception is the formation of
monomeric PhGdCl2(THF)4 [21]. The compound 1 is
inert to hydrogen, phenylacetylene, (SiMe3)2NH in
toluene and even to (SiMe3)2CHLi dissolved in toluene.
When excess of [2,6-(iPrO)2C6H3]Li was added to
The crystal data and experimental factors for com-
pound 2 is shown in Table 1. The selected bond dis-
tances and angles are listed in Table 2. The
C(11)–Sm–C(21) angle (141.4°) is wider than 129.7–
115.5° observed for Cp(centroid)–Sm–I angle of
[(C5Me5)2Sm(v-I)(THF)2]2 [22] and 104.5° observed for
O(1)–Sm–Cp(centroid) in (C5Me5)2SmMe(THF) [23]
while the angles of C(21)–Sm–C(31), C(21)–Sm–C(41)
and C(31)–Sm–C(41) are narrower than these angles.
The observed Sm-phenyl distance is longer than 2.511
˚
A in (C5Me5)2SmPh [24]. The Sm–O(160) and Sm–
O(220) distances are nearly equal to the Sm–O distance
˚
(2.62–2.64 A) of (C5Me5)2Sm(THF)2 [22] but Sm–
O(360) and Sm–O(420) distances are shorter than those
of (C5Me5)2Sm(THF)2. However, these values are ap-
˚
parently longer than Sm–O distance (2.473 A) in
SmCl3
(3:1–4:1),
an
ate
complex
[2,6-

150
E. Ihara et al. / Journal of Organometallic Chemistry 569 (1998) 147–157
Fig. 3. 1H-NMR spectrum of [2,6-(iPrO)2C6H3]4SmLi 2 in C6D5CD3, (a) −78°C and (b) 90°C.

E. Ihara et al. / Journal of Organometallic Chemistry 569 (1998) 147–157
151
Table 1
Crystal data and experimental factoris for [2,6-(iPrO)2C6H3]4SmLi 2
Experimental formula
Formula weight
Crystal color
C48H68O8SmLi
930.4
Colorless
C2/c (c15)
23°C
47.52(1)
11.680(9)
18.862(9)
112.19
9694(8)
8
Space group
Temperature
˚
a (A)
˚
b (A)
Scheme 3.
˚
c (A)
i (°)
V (A )
3
˚
LaCl3(THF)2 gave colorless crystals of [2,6-
(iPrO)2C6H3]3La 3 in high yield (Scheme 3), whose
NMR spectrum is quite the same as that of [2,6-
(iPrO)2C6H3]3Sm (Me, d 0.74 ppm; Me, d 1.72 ppm,
CH, sept 4.3 ppm; m-C6H3, d 6.35 ppm; p-C6H3, t 6.95
ppm). This compound shows monomeric structure as
revealed by measurement of molecular weight. How-
ever, the present compound was found to be inert
toward the polymerization of methyl methacrylate.
Z
Dcalc. (g cm−3
F(000)
)
1.450
3880
12.62
(MoKh) (cm−1
)
Crystal dimension
2q range (°)
03×0.25×0.20 mm
3B2qB55
1.37+0.35 tan q
10.0
5=0.07sured 11911
6296
No
523
4.91
Scan width 2q
Scan speed (° min−1
Back ground(s)
Reflection observed
Radiation damage
Number of variables
GOF
)
2.3. Synthesis of [2,6-(iPrO)2C6H3]2Yb[CH(SiMe3)2]2Li
R
0.077
Rw
0.074
Among the heavy rare earth metals, the element Yb
was selected because its ionic radius is very small (0.87
i
˚
A). The 2:1 reaction of [2,6-( PrO)2C6H3]Li with YbCl3
in THF gave polymeric species as orange powder,
presumably {[2,6-(iPrO)2C6H3]2YbCl}n (Scheme 4). The
resulting compound is soluble in toluene and showed
paramagnetic nature as revealed by NMR studies.
When (Me3Si)2CHLi was added to this compound,
vigorous reaction takes place to give a red solution.
After the recrystallization in toluene/hexane, single
crystal of ate complex, [2,6-(iPrO)2C6H3]2Yb-
[CH(SiMe3)2]2Li 4, was obtained in high yield. Com-
pound 4 exhibits a monomeric nature as evidenced by
the molecular weight measurement. The presence of the
Li atom is clarified by the titration with aq. HCI
(C5Me5)2SmMe(THF) [23]. Therefore, co-ordination
strength of isopropoxy group in the present compound
seems weaker than that in (C5Me5)2SmMe(THF). To
evaluate this nature, variable temperature NMR spec-
tra were recorded. At −90°C, 1H NMR spectrum
shows very complicated spectrum, while simple spec-
trum was observed at 100°C to indicate that all the
isopropoxy groups are equivalent because of the cleav-
age of their co-ordination to the Sm atom (Me 1.72
ppm, CH 3.95 ppm, m-C6H3 5.92 ppm, p-C6H3 7.12
ppm) (Fig. 3).
1
(observed 0.97 eq., calc. 1.0). H NMR spectrum of 4 is
2.2. Synthesis of [2,6-(iPrO)2C6H3]3La
shown in Fig. 4. The 2H protons which were ascribed
to p, m-phenyl group were observed at 17.28, 19.98,
24.59, 46.35 and 54.19 ppm. The 6H(doublet) protons
for Me groups were observed at 5.77, 16.44, 22.33, and
36.92 ppm, to indicate that rotation around the ligand
is restricted in the observed temperature (25°C).
˚
The La atom exhibits the largest ionic radius (1.03 A)
among the rare earth metals. Therefore, higher catalytic
activity is expected to the corresponding trivalent com-
pound. The 2:1 reaction of [2,6-(iPrO)2C6H3]Li with
Table 2
˚
Selected bond distances (A) and angles (°) of compound 2
Sm–Li
3.01(4)
1.97(4)
2.22(4)
2.26(4)
Sm–C(11)
Sm–C(21)
Sm–C(31)
Sm–C(41)
2.58(2)
2.62(2)
2.60(2)
2.60(2)
Sm–0(160)
Sm–0(220)
Sm–0(360)
Sm–0(420)
2.61(1)
2.67(1)
2.57(1)
2.59(1)
Li–0(260)
Li–0(320)
Li–0(460)
C(11)–Sm–C(21)
C(11)–Sm–C(31)
C(11)–Sm–C(41)
141.4(6)
124.1(6)
120.5(6)
C(21)–Sm–C(31)
C(21)–Sm–C(41)
C(31)–Sm–C(41)
80.1(6)
90.3(6)
81.1(6)

152
E. Ihara et al. / Journal of Organometallic Chemistry 569 (1998) 147–157
When the compound [2,6-(iPrO)2C6H3]2YbCl was
Thus, we have failed the synthesis of [2,6-(cyclo-
C6H11O)2C6H3]2SmCl, despite the introduction of bulky
group.
kept in ether at room temperature for two or three
weeks, a disproportionation reaction occurred to pre-
cipitate [2,6-(iPrO)2C6H3]3Yb 5 in ca 45% yield. 1H
NMR spectrum of 5 shows the same pattern as that of
1 (Me −4.88, 15.38 ppm, CH 18.03 ppm, p- and
m-C6H3 19.36, 20.92 ppm) although chemical shift val-
ues are different due to its paramagnetic nature.
2.5. Polymerization beha6ior of ‡-caprolactone and alkyl
isocyanates
Among the organolanthanide compounds synthe-
sized in this paper, we have explored the catalytic
action of 1, 2 and 5 toward the polymerization of
‡-caprolactone, alkyl isocyanates and methyl
methacrylate. The polymerizations of alkyl isocynates
and ‡-caprolactone by 1 is given in Table 3. Polymer-
ization of n-hexyl isocyanate could be performed at
temperatures higher than 0°C as was observed in the
case of TiCl3(CH2CF3) which gave very narrow molec-
ular weight distribution at room temperature (Mw/
Mn=1.1–1.3) [25], while most organolanthanides such
as Ln(O–iPr)3 show good catalytic activity only at
lower temperature (B40°C) to give high molecular
weight (Mn\106) poly(hexyl isocyanate) with Mw/Mn
of 2.08–3.16 [26]. Hexyl isocyanate was converted to
cyclic trimer when the reaction was carried out at
room temperature. The polymerization of ‡-caprolac-
tone proceeded smoothly to give high molecular
weight polymers with relatively low polydispersity. On
the other hand, this complex conducted no polymer-
ization of methyl methacrylate and styrene. The com-
plex 2 serves as good initiator for the polymerization
of ‡-caprolactone and produced poly(‡-caprolactone)
quantitatively within 3 h under the mild conditions
(25°C) (Table 4). Polymerization of methyl methacry-
late also proceeds by 2, but the resulting yield and
stereospecificity is very low. Polymerization of ‡-
caprolactone is also conducted by 5. The polymer was
obtained quantitatively at 0°C (Mn=5.2×104, Mw/
Mn=1.43). Polymerization of n-hexyl isocyanate oc-
curs at 0°C, but the yield is rather low due to the
contamination by cyclic trimers. Thus, the compounds
1, 2 and 5 are effective for the polymerization of ‡-
caprolactone.
2.4. Synthesis of [2,6-(cyclo-C6H11–O)2C6H3]3Sm
Introduction of the bulky alkoxy group may result in
the enhanced stability of the compound and 1,3-bis(cy-
clohexyloxy)phenyl ligand was synthesized as men-
tioned in Section 3. After treating it with n-BuLi, the
resulting 2,6-(cyclo-C6H11O)2C6H3Li was reacted with
anhydrous SmCl3 in 2:1 ratio to give [2,6-(cyclo-
C6H11O)2C6H3]3Sm 6, as yellow crystals exclusively
without formation of [2,6-(cyclo-C6H11O)2C6H3]2SmCl
(Scheme 5). The compound 6 is monomeric as evi-
denced by the molecular weight measurement. 1H
NMR spectrum of 6 is shown in Fig. 5. The signal of
m- and p-C6H3 groups were observed at 5.63 and 6.62
ppm, respectively. No co-ordination of solvent was
observed, even when the compound was dissolved in
THF.
Thus [2,6-(cyclo-C6H11–O)2C6H3]2SmCl formed as
transient intermediate was more reactive than SmCl3.
3. Experimental section
3.1. General
All manipulations were carried out by using a stan-
dard Schlenk technique under an argon atmosphere.
Toluene and THF were dried over calcium hydride,
then over sodium benzophenone ketyl and distilled
before use. NMR spectra were recorded on a JEOL
JNM-LA400 and Bruker AM-X400wb instruments.
Chemical shifts were calibrated using benzene (7.2
ppm), chloroform (7.26 ppm) and toluene (2.09 ppm).
Scheme 4.

E. Ihara et al. / Journal of Organometallic Chemistry 569 (1998) 147–157
153
Fig. 4. 1H NMR spectrum of [2,6-(iPrO)2C6H3]2Yb[CH(SiMe3)2]2Li 4 in C6D6.
3.2. Synthesis of SmCl3 and LaCl3(THF)2
The X-ray diffraction data were collected on
a
Rigaku AFCSR diffractometer using a suitable crys-
tal sealed in a thin-walled glass capillary tube under
argon. Number-average molecular weights and
molecular weight distributions of the resulting poly-
mers were determined by gel-permeation chromatog-
raphy on a Tosoh SC- 8010 high speed liquid
chromatograph equipped with a differential refrac-
tometer using columns TSK gel G1000, G2000,
G3000 and G4000 in CHCl3 at 40°C. The molecular
weights of polymers were determined with calibra-
tion curves obtained using standard polystyrene.
A mixture of Sm2O3 (10 g, 28.7 mmol), NH4Cl
(10 g, 186 mmol) and 150 ml of 12N aq. HCl were
placed in a 500 ml round flask, fitted with a reflux
condenser. The suspension was refluxed for 5 h and
the color of the solution turned from yellow to
gray. Removal of the solvent by flash distillation re-
sulted in a white solid. Sublimation (360°C, 30 h) of
the solid to remove the excess NH4Cl gave anhy-
drous SmCl3 (13.86 g, 27 mmol) in 94% yield as
residue.
Suspension of 1.0 g (7.20 mmol) of powdered La
metal and 3.0 g (12.7 mmol) of C2Cl6 in 40 ml of
THF were treated in an ultrasonic bath at room
temperature until all the metal powder disappeared,
after ca. 5 h. Hexane (20 ml) was added to the re-
sulting white suspension and the liquid was decanted
from the white precipitate, which was then washed
with hexane several times. Drying the white solid in
vacuo for 1 h resulted in LaCl3(THF)2 (2.24 g, 5.76
mmol) in 80% yield.
Scheme 5.

154
E. Ihara et al. / Journal of Organometallic Chemistry 569 (1998) 147–157
Fig. 5. 1H NMR spectrum of [2,6-(cyclo-C6H11O)2C6H3]3Sm 5 in C6D6.
3.3. Synthesis of [2,6-(iPrO)2C6H3]3Sm 1
tion mixture and the organic layer was extracted using
two portions of hexane (40 ml each). The combined
organic solution was washed three times with 50 ml of
NaOH aq. solution (1N) to remove unreacted resor-
cinol. Removal of the solvent by flash distillation
yielded 7.3 g (37.6 mmol, 81%) of 1,3-(iPrO)2C6H4 as a
i
Resorcinol (5.1 g, 46.3 mmol), Pr–Br (17 ml, 181
mmol), K2CO3 (25 g, 181 mmol) and 100 ml of DMF
were placed in a 500 ml round bottomed flask fitted
with a reflux condensor. The suspension was refluxed
for at least 4h. After completion of the reaction, water
(100 ml) and hexane (100 ml) were added to the reac-
1
pale-yellow oil. H NMR (CDCl3, 400 MHz): l 1.32 (d,
12H, J=6.2 Hz), 4.52 (sept, 2H, J=6.2 Hz), 6.45 (m,
Table 3
Polymerizations of isocyanates and ‡-caprolactone with [2,6-(iPrO)2C6H5]3Sm 1
Monomer
Catalyst concentration (mol %)
Polymerization time (h)
Temperature (°C)
Yield (%)
Mn (×104) Mw/
Mn
n-HexNCO
0.5a
0.5a
1.0a
0.5b
0.5b
0.5c
0.75d
0.75d
0.5
24
24
24
24
24
24
24
48
18
6
0
25
25
0
25
25
25
25
−78
25
0
19
32
0
0
2
15
15
0
—
—
74.6
59.0
—
—
9.18
2.50
2.28
—
—
8.14
3.47
2.69
n-BuNCO
41.0
37.8
Caprolactone
0.5
100
7.87
1.56
a Toluene 0.5 ml, initiator 0.04 mmol.
b THF 0.5 ml, initiator 0.04 mmol.
c No solvent.
d Toluene 0.6 ml, initiator 0.065 mmol.

E. Ihara et al. / Journal of Organometallic Chemistry 569 (1998) 147–157
155
Table 4
Polymerizations of caprolactone and methyl methacrylate with [2,6-(iPrO)2C6H5]4SmLi 2a
Monomer
Catalyst concentration (mol%)
Polymerization time (h)
Temperature (°C)
Yield (%)
Mn (×104) Mw/
Mn
Caprolactone
0.25
0.1
0.4
0.8
0.8
3
3
19
19
19
25
25
0
25
50
84
100
3
8
9
2.9
8.9
1.44
0.78
0.77
1.53
2.07
3.06
3.67
4.89
Methyl
Methacrylate
a Toluene 10 ml, initiator 0.04 mmol.
mmol, 45%) at −25°C. 1H NMR (C6D5CD3, 400
MHz, 100°C): l 0.71 (bs, 48H), 3.90 (bs, 8H), 5.86 (bs,
8H), 7.06 (bs, 4H).
3H), 7.14 (t, 1H). A hexane solution of n-BuLi (1.65 M,
8.5 ml, 14 mmol) was syringed into a solution of
1,3-(iPrO)2C6H4 (2.7 g, 14 mmol) in THF (30 ml) at
0°C. After stirring the mixture for 3 h, it was allowed to
warm to room temperature to generate 2,6-
(iPrO)2C6H3Li. To a stirred suspension of SmCl3 (4.9 g,
15.6 mmol) in THF (70 ml), 2,6-(iPrO)2C6H3Li (30.5
ml) was added. Stirring was continued further for 30 h.
The solvent was evaporated in vacuo and the residual
pale orange solid was dissolved in toluene (100 ml).
After the removal of LiCl by decantation, the solution
was evaporated to dryness. Recrystallization of the
residual powder from THF/hexane (1:1) yielded the
desired [2,6-(iPrO)2C6H3]3Sm (4.8 g, 6.6 mmol, 65%) as
yellow crystals. 1H NMR (CDCl3, 400 MHz): l 0.86 (d,
18H, J=6.2 Hz), 1.47 (d, 18H, J=6.2 Hz), 4.27 (sept
6H, J=6.2 Hz), 5.42 (d, 6H, J=8.0 Hz), 6.57 (t, 6H,
J=8.0 Hz).
3.5. Synthesis of [2,6-(iPrO)2C6H3]3YD 3
At room temperature, some 2,6-(iPrO)2C6H3Li (24.7
mmol) was added to a stirred suspension of LaCl3 (2.2
g, 5.7 mmol) in THF (30 ml). Stirring was continued
for 10 h.
The solvent was then evaporated in vacuo and the
residual pale orange solid was dissolved in toluene (100
ml). After the removal of LiCl by decantation, the
solution was evaporated to dryness to give orange
powder. Recrystallization of the residual powder from
ether at room temperature yielded the desired [2,6-
(iPrO)2C6H3]3La (1.7 g, 2.4 mmol, 65% yield) as white
1
crystals. H NMR (C6D6, 400 MHz, 25°C): l 0.76(a,
18H), 1.67(h, 18H), 4.41(sep. 6H), 6.37(bs, 6H), 6.98(A,
3H). Molecular weight was determined cryoscopically
in benzene; calc. 717.9, observed 723, for monomeric
species.
3.4. Synthesis of[2,6-(iPrO)2C6H3]4SmLi 2
At room temperature,
a
solution of 2,6-
(iPrO)2C6H3Li (24.7 mmol) dissolved in THF (50 ml)
was added to a stirred suspension of SmCl3 (2.07 g,
8.06 mmol) in THF (60 ml). Stirring was continued for
10 h and the solution was evaporated to dryness. The
residual pale orange solid was dissolved in hexane (100
ml) and, after the removal of LiCl by decantation, THF
(15 ml) was added to the hexane solution to induce the
colorless crystals of [2,6-(iPrO)2C6H3]4SmLi (2.9 g, 2.74
3.6. Synthesis of [2,6-(iPrO) 2C6H3]2Yb[CH(SiMe3)2]2Li
4
A solution of 2,6-(iPr0)2C6H3Li (12.9 mmol) dis-
solved in THF (40 ml) was added at room temperature,
to a stirred suspension of YbCl3 (1.9 g, 6.8 mmol) in
THF (40 ml). After stirring overnight, the solution was
evaporated in vacuo and the residue was dissolved in
Table 5
Polymerization of caprolactone and hexyl isocyanate with [2,6-(iPrO)2C6H5]2Yb[CH(SiMe3)2]2Li 4a
Monomer
Catalyst concentration (mol%)
Polymerization time (h)
Temperature (°C)
Yield (%)
Mn (×104) Mw/
Mn
Caprolactone
n-HexNCO
0.3
0.3
0.3
0.5
0.5
−78
0
25
−78
0
17
4
4
13
13
23
100
100
0
40
4.8
4.2
4.93
1.53
1.57
18
5.5
13.8
a Toluene 5 ml, imitator 0.04 mmol.

156
E. Ihara et al. / Journal of Organometallic Chemistry 569 (1998) 147–157
Table 6
toluene (100 ml). After the removal of LiC1 by decanta-
tion, toluene was evaporated in vacuo to give orange
residue, which was then washed with hexane (30 ml×
3) to remove [2,6-(iPrO)2C6H3]4YbLi. Drying of orange
solid in vacuo for 1 h afforded orange powder of
Final atomic co-ordinates and equivalent isotropic temperature fac-
tors for non-hydrogen atoms in [2,6-(iPrO)2C6H3]4SmLi 2
2
˚
Atom
x
y
z
Beq (A )
[2,6(iPr0)2C6H3]2YbCl. To
a
solution of [2,6-
Sm
0.11138(2)
0.0472(3)
0.0768(3)
0.0811(3)
0.1848(3)
0.2024(3)
0.1087(3)
0.1277(3)
0.1852(4)
0.0611(4)
0.0405(5)
0.0162(6)
0.0117(6)
0.0313(6)
0.0555(5)
0.1326(4)
0.1054(4)
0.1009(6)
0.1263(6)
0.1540(6)
0.1572(5)
0.1558(5)
0.1847(4)
0.1947(5)
0.1752(6)
0.1469(5)
0.1384(5)
0.1538(5)
0.1476(5)
0.1593(5)
0.1788(6)
0.1875(5)
0.1752(5)
0.0392(8)
0.0309(6)
0.0372(8)
0.0923(6)
0.0750(6)
0.0880(7)
0.0497(6)
0.0513(5)
0.0280(4)
0.1986(7)
0.2081(6)
0.2372(6)
0.2463(6)
0.2289(5)
0.2186(7)
0.0616(6)
0.0922(5)
0.1085(7)
0.1012(6)
0.1270(5)
0.1225(6)
0.1761(8)
0.1966(8)
0.2088(8)
0.1770(8)
0.27104(8) 0.64969(5)
2.69(2)
4.8(4)
3.8(3)
3.3(3)
4.4(3)
4.7(4)
3.7(3)
3.7(3)
5.9(4)
3.6(4)
3.9(5)
6.2(7)
6.4(7)
5.2(6)
3.7(5)
3.1(4)
3.5(4)
5.1(5)
6.0(7)
5.1(6)
3.8(5)
3.0(4)
3.6(4)
5.1(6)
5.3(6)
4.1(5)
3.3(4)
3.3(4)
3.4(4)
4.5(6)
5.5(7)
4.9(6)
3.9(5)
9.2(10)
7.6(8)
9.2(10)
6.1(7)
4.8(6)
6.6(8)
6.1(7)
4.0(5)
5.1(6)
7.4(9)
5.7(7)
8.3(8)
7.8(9)
5.7(6)
8.4(9)
5.6(6)
4.3(5)
6.3(7)
6.4(7)
4.2(6)
5.7(7)
10(1)
(iPr0)2C6H3]2YbC1 (3.0 mmol) in toluene (100 ml) was
added ether solution of (Me3Si)2CHLi (0.97 M, 6.2 ml,
6.0 mmol) at 0°C. After stirring the mixture for 10 h,
LiC1 was removed by decantation. Solvent was evapo-
rated and the residue was washed with hexane (100 ml).
Recrystallization from toluene/hexane afforded dark
red crystals of [2,6-(iPr0)2C6H3]2Yb[CH(SiMe3)2]2Li (1.4
O(120)
O(160)
O(220)
O(260)
O(320)
O(360)
O(420)
O(460)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(31)
0.086(1)
0.447(1)
0.301(1)
0.212(1)
0.214(1)
0.052(1)
0.335(1)
0.478(1)
0.267(2)
0.204(2)
0.253(2)
0.367(2)
0.439(2)
0.385(2)
0.257(2)
0.261(2)
0.227(2)
0.188(3)
0.182(2)
0.213(2)
0.128(2)
0.115(2)
0.007(2)
−0.087(2)
−0.078(2)
0.036(2)
0.416(2)
0.422(2)
0.503(2)
0.584(2)
0.580(2)
0.497(2)
0.020(3)
0.010(2)
−0.109(2)
0.600(2)
0.571(2)
0.632(2)
0.418(2)
0.313(2)
0.313(2)
0.009(2)
0.132(2)
0.163(3)
0.330(2)
0.221(2)
0.234(3)
0.009(2)
−0.039(2)
−0.080(2)
0.358(3)
0.296(2)
0.165(2)
0.659(3)
0.564(3)
0.504(3)
0.289(3)
0.4777(9)
0.5891(8)
0.7425(7)
0.8546(7)
0.6897(9)
0.6595(8)
0.5396(7)
0.7806(9)
0.532(1)
0.472(1)
0.412(1)
0.411(1)
0.468(1)
0.527(1)
0.7994(9)
0.810(1)
0.875(1)
0.935(1)
0.930(1)
0.863(1)
0.672(1)
0.670(1)
0.655(1)
0.0642(1)
0.644(1)
0.658(1)
0.658(1)
0.579(1)
0.544(1)
0.589(2)
0.668(1)
0.702(1)
0.349(2)
0.415(2)
0.453(2)
0.678(2)
0.595(1)
0.542(2)
0.792(2)
0.746(1)
0.66411)
0.885(2)
0.904(1)
0.891(2)
0.710(2)
0.669(2)
0.580(2)
0.669(1)
0.679(1)
0.760(1)
0.402(1)
0.465(1)
0.465(1)
0.831(2)
0.836(2)
0.914(2)
0.756(2)
1
g, 1.6 mmol, yield 23%). H NMR (400 MHz,C6D6,
25°C) l-14.06 (bs, 36H), 5.77 (d, 6H), 16.44 (d, 6H),
17.28 (bs, 2H), 19.98 (bs, 2H), 22.33 (d, 6H), 24.59 (bs,
2H), 36.92 (d, 6H), 46.35 (bs, 4H), 54.19(bs, 2H).
Molecular weight was determined cryoscopically in
benzene; cakcd. 884.3, observed 890 for monomeric
species (Table 5).
3.7. Synthesis of [2,6-(cyclo-C6H11–0)2C6H3]Sm 6
A solution of azodicarboxylic acid diisopropyl ester
(100 g, 495 mmol) in toluene (150 ml) was syringed to
a mixed solution of resorcinol (20 g, 182 ml), cyclohex-
anol (57.6 g, 545 mmol) and triphenylphosphine (140.3
g, 535 mmol) in THF (200 ml) held at 0°C. After
stirring for 24 h at room temperature, the reaction
mixture was treated with 30% H2O2 (40 ml) to oxydize
the unreacted PPh3 to PPh3O. Addition of hexane (300
ml) induced the precipitation of PPh3O, which was then
removed by filtration. The aqueous layer of the filtrate
was separated from the organic layer, which was then
extracted twice with 40 ml portions of hexane. The
combined hexane solution was washed three times with
50 ml of NaOH aqueous solutions (1N) to remove
unreacted resorcinol and mono-substituted compound.
Removal of solvent by flash distillation yielded 1,3-(cy-
clo-C6H11–O)C6H4 as a pale yellow oil. Purification by
column chromatography [Wako-gel C-200 as silica-gel
and hexane/EtOAc (2:1) as eluent], followed by Kugel-
rour distillation afforded pure 1,3-(cyclo-C6H11–O)-
C(32)
C(33)
C(34)
C(35)
C(36)
C(41)
C(42)
C(43)
C(44)
C(45)
C(46)
C(121)
C(122)
C(123)
C(161)
C(162)
C(163)
C(221)
C(222)
C(223)
C(261)
C(262)
C(263)
C(321)
C(322)
C(323)
C(361)
C(362)
C(363)
C(424)
C(425)
C(426)
C(461)
C(462)
C(463)
Li
1
C6H4 (bp. 170–200°C, 29 g, 106 mmol, 58% yield). H
NMR (CDCl3, 400 MHz, 25°C): l −1.00 to 2.00 (m,
20H), 4.13 (t, 2H, J=3.8 Hz, 9.1 Hz), 6.39 (m, 3H),
7.05 m, 1H). Hexane solution of n-BuLi (1.63M, 5.3
ml, 8.6 mmol) was syringed to a solution of 1,3-(cyclo-
C6H11–O)C6H4 (2.4 g, 8.6 mmol) in THF (20 ml) at
0°C. The color of the solution turned dark red. After
stirring for 3 h at 0°C, the mixture was allowed to
warm to room temperature to generate 2,6-(cyclo-
C6H11–O)C6H3Li (90% yield). To a stirred suspension
of SmCl3 (1.9 g, 7.4 mmol) in THF (35 ml), 2,6-(cyclo-
C6H11–O)C6H3Li (13.5 mmol) and TMEDA (4.1 ml,
27.2 mmol) was added. Stirring was continued for 2 h.
7.5(9)
9.5(10)
4.6(8)

E. Ihara et al. / Journal of Organometallic Chemistry 569 (1998) 147–157
157
tors for non-hydrogen atoms for complex 2 are listed in
Table 6.
The solution was evaporated to dryness and hexane
(120 ml) was added to the residual orange powder.
After stirring for 3 h, the hexane soluble part was
concentrated to give the desired [2,6-(cyclo-C6H11–O)2-
C6H3]3Sm (0.7 g). The hexane insoluble part was dis-
solved in toluene (50 ml) and after the removal of LiCl,
the solution was concentrated to give 2.1 g of [2,6-(cy-
clo-C6H11–O)2C6H3]3Sm. Combined yield, 64%. 1H
NMR (C6D6, 400 MHz, 25°C): l 1.0–2.5 (m, 60H),
4.10 (bs, 6H), 5.64 (d, 6H), 6.64 (t, 6H). Molecular
weight is determined cryoscopically in benzene, calc.
933.4. Observed 945.
References
[1] F.A. Hart, A.G. Massay, M.S. Saran, J. Organomet. Chem. 21
(1970) 147.
[2] L.E. Manzer, J. Am. Chem. Soc. 100 (1978) 8068.
[3] A.L. Wayda, J.L. Atwood, W.E. Hunter, Organometallics 3
(1984) 939.
[4] M. Booij, N.H. Kiers, H.J. Heeres, J.H. Teuben, J. Organomet.
Chem. 364 (1989) 79.
[5] G.B. Deacon, D.G. Vince, J. Organomet. Chem. 112 (1976) C1.
[6] G.B. Deacon, W.D. Raverty, D.G. Vince, J. Organomet. Chem.
135 (1977) 103.
3.8. Typical procedure for the polymerization of polar
monomers (MMA, ‡-caprolactone, alkyl isocyanate)
[7] GB. Deacon, A.J. Koplick, W.D. Raverty, D.G. Vince, J.
Organomet. Chem. 182 (1979) 121.
[8] G.Z. Suleimanov, RN. Khandozhko, RY. Mekhdiev, P.V. Petro-
vsky, T.A. Agdamsky, N.E. Kolobova, I.P. Beletskaya, Dokl.
Akad. Nauk SSSR 284 (1985) 1376.
[9] T.A. Starostina, R.R Shifrina, L.F. Rybakova, E.S. Petrov, Zh.
Obshch. Khim. 57 (1987) 2402.
[10] L.N. Bochkarev, T.A. Stepantseva, L.N. Zakharov, G.K. Fukin,
A.I. Yanovsky, Y.T. Struchkov, Organometallics 14 (1995) 2127.
[11] M.N. Bochkarev, V.V. Khramenkov, Y.F. Radkov, L.N. Za-
kharov, Y.T. Struchkov, J. Organomet. Chem. 429 (1992) 27.
[12] A.B. Sigalov, L.F. Rybakova, I.P. Beletskaya, Izv. Akad. Nauk.
SSSR Ser. Khim. 1208 (1983).
[13] A.B. Sigalov, E.S.Petrov, L.F. Rybakova, I.P. Beletskaya, Izv.
Akad. Nauk. SSSR, Ser. Khim. 2615 (1983).
[14] A.B. Sigalov, I.P. Beletskaya, Izv. Akad. Nauk SSSR, Ser.
Khim. 445 (1988).
[15] F.T. Edelmann, Angew. Chem. Int. Ed. Engl. 34 (1995) 2466.
[16] A.L. Wayda, R.D. Rogers, Organometallics 4 (1985) 1440.
[17] M. Booij, N.H. Kiers, A. Meetsma, J.H. Teuben, Organometal-
lics 8 (1989) 2454.
[18] S.A. Cotton, F.A. Hart, M.B. Hursthouse, A.J. Welch, J. Chem.
Soc. Chem. Commun. (1972) 1225.
[19] F.A. Hart, M.S. Salan, J. Chem. Soc. Chem. Commun. (1968)
1614.
[20] F.A. Hurt, A.G. Massey, M.S. Salan, J.Organomet. Chem. 21
(1970) 247.
[21] G. Lin, Z. Jin, Y. Zhang, W. Chen, J. Organomet. Chem. 396
(1990) 307.
[22] W.J. Evans, J.W. Grate, H.W. Choi, I. Broom, W.E. Hunter,
J.L. Atwood, J. Am. Chem. Soc. 107 (1985) 941.
[23] W.J. Evans, L.R. Chamberlain, T.A. Ulibarri, J.W. Ziller, J.
Am. Chem. Soc. 110 (1988) 6423.
[24] W.J. Evans, I. Bloom, W.E. Hunter, J.L. Atwood, Organometal-
ics 4 (1985) 112.
[25] (a)T.E. Patten, B.M. Novak, J. Am. Chem. Soc. 113 (1991) 5065.
(b) T.E. Patten, B.M. Novak, Makromol. Chem. Macromol.
Symp. 67 (1993) 203.
[26] N. Fukuwatari, H. Sugimoto, S. Inoue, Macromol. Rapid Com-
mun. 17 (1996) 1.
[27] teXsan: Crystal Structure Analysis Package, Molecular Structure
Corporation (1985 & 1992).
Monomer (MMA and ‡-caprolactone, typically 100–
200 eqivalents 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. When alkyl isocyanares were polymerized,
0.5 ml (or none) of toluene was used. After stirring for
a fixed time, the reaction mixture was quenched by the
addition of excess MeOH. The preciptated polymer was
collected and dried under vacuum.
3.9. X-ray structural determination of [2,6-(iPrO)2-
C6H3]4SmLi 2
The integrated intensity data were measured on a
Rigaku AFC-5R diffractometer with graphite-
monochromated Mo–Kh (u=0.7106A) radiation. As
complex 2 is very air-sensitive, the crystals were sealed
in a thin-walled glass capillary tube under argon atmo-
sphere. The X-ray data were collected at room temper-
ature using ꢀ-2q scan technique to a maximum 2q
value of 55.0°. The data were corrected for conven-
tional absorption, Lorentz and polarization effects.
The crystal structure was solved by the heavy-atom
method. The Sm atom was found in the Patterson map.
Successive Fourier syntheses clearly revealed the re-
maining non-hydrogen atoms. The non-hydrogen
atoms were refined anisotropically 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 software package [27]. The final atomic
co-ordinates and equivalent isotropic temperature fac-
.