Synthesis, characterization of some organolanthanide complexes containing 2-pyridylmethyl substituted fluorenyl ligand and catalytic activity of organolanthanide(II) complexes

Article abstract of DOI:10.1016/j.ica.2009.12.058

A series of organolanthanide complexes with 2-pyridylmethyl substituted fluorenyl ligand were synthesized via reaction of (Me₃Si)₂N₃Ln^III(μ-Cl)Li (THF)₃ (Ln = Yb, Eu, Nd, Y) with the functionalized fluorene compound. Treatment of (Me₃Si)₂N₃Ln^III(μ-Cl)Li (THF)₃ (Ln = Yb, Eu) with 2 equiv. of C₅H₄NCH₂C₁₃H₉ (1) at 60-80 °C in toluene afforded the corresponding organolanthanide(II) complexes with formula η⁵:η¹- C₅H₄NCH₂C₁₃H_{8 2}Ln Ln = Yb (2), Eu (3) via tandem silylamine elimination/homolysis of the Ln-N bond reaction. Reaction of (Me₃Si)₂N₃Ln^III(μ-Cl)Li (THF)₃ (Ln = Y, Nd) with 2 equiv. of C₅H₄NCH₂C₁₃H₉ in toluene at 80 °C produced the corresponding organolanthanide(III) complexes with formula η⁵:η¹-C₅H₄NCH ₂C₁₃H₈₂LnCl Ln = Y (4), Nd (5)]. Complexes 4 and 5 could also be prepared by treatment of 2 equiv. of lithium fluorenide η⁵:η¹-C₅H₄NCH ₂C₁₃H₈ Li(THF)₂ (6) with corresponding LnCl₃. All compounds were fully characterized by spectroscopic methods and elemental analyses. The structures of complexes 4 and 6 were additionally determined by single-crystal X-ray analyses. The catalytic properties of the divalent organolanthanide complexes 2 and 3 on the ring-opening polymerization of ε-caprolactone (CL) have been studied. The temperatures, solvents effects on the catalytic activities of the complexes were examined.

Full text of DOI:10.1016/j.ica.2009.12.058

Inorganica Chimica Acta 363 (2010) 1325–1331
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Inorganica Chimica Acta
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Synthesis, characterization of some organolanthanide complexes containing
2-pyridylmethyl substituted fluorenyl ligand and catalytic activity
of organolanthanide(II) complexes
a
a
a
a
Hui Miao a, Shaowu Wang a,b, , Shuangliu Zhou , Yun Wei , Zhihong Zhou , Hong Zhu ,
*
Shihong Wu a, Hui Wang a
a Laboratory of Functionalized Molecular Solids, Ministry of Education, Anhui Laboratory of Molecule-Based Materials, Institute of Organic Chemistry,
School of Chemistry and Materials Science, Anhui Normal University, Wuhu, Anhui 241000, China
b State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 9 August 2009
Received in revised form 25 December 2009
Accepted 30 December 2009
Available online 6 January 2010
A series of organolanthanide complexes with 2-pyridylmethyl substituted fluorenyl ligand were synthe-
sized via reaction of [(Me3Si)2N]3LnIII
(
l
-Cl)Li(THF)3 (Ln = Yb, Eu, Nd, Y) with the functionalized fluorene
compound. Treatment of [(Me3Si)2N]3LnIII
-Cl)Li(THF)3 (Ln = Yb, Eu) with 2 equiv. of C5H4NCH2C13H9 (1)
at 60–80 °C in toluene afforded the corresponding organolanthanide(II) complexes with formula [g5
C5H4NCH2C13H8]2Ln [Ln = Yb (2), Eu (3)] via tandem silylamine elimination/homolysis of the Ln–N bond
reaction. Reaction of [(Me3Si)2N]3LnIII
-Cl)Li(THF)3 (Ln = Y, Nd) with 2 equiv. of C5H4NCH2C13H9 in tol-
uene at 80 °C produced the corresponding organolanthanide(III) complexes with formula
C5H4NCH2C13H8]2LnCl [Ln = Y (4), Nd (5)]. Complexes 4 and 5 could also be prepared by treatment of 2
equiv. of lithium fluorenide [g5 1-C5H4NCH2C13H8]Li(THF)2 (6) with corresponding LnCl3. All compounds
(
l
:
g1
-
(
l
Keywords:
Synthesis
Homolysis
Lanthanide
Catalysis
[
g5 g1
: -
:
g
were fully characterized by spectroscopic methods and elemental analyses. The structures of complexes 4
and 6 were additionally determined by single-crystal X-ray analyses. The catalytic properties of the diva-
Polymerization
lent organolanthanide complexes 2 and 3 on the ring-opening polymerization of e-caprolactone (CL) have
been studied. The temperatures, solvents effects on the catalytic activities of the complexes were
examined.
Ó 2010 Elsevier B.V. All rights reserved.
1. Introduction
dene compounds with the lanthanide(III) amides [(Me3Si)2N]3-
Ln(l-Cl)Li(THF)3 (Ln = Yb, Eu) [8–13]. The formation pathway of
Over the past few decades, a great progress has been made in
the chemistry of divalent organolanthanide complexes. Divalent
organolanthanide complexes are one of the families of the organo-
lanthanide complexes which exhibited a particularly rich reaction
chemistry based on their strong reductive property [1–3]. A variety
of organolanthanide(II) complexes have been synthesized and used
in organic synthesis and polymer chemistry [4–6]. Generally, diva-
lent organolanthanide complexes were synthesized by the metath-
esis reaction of alkaline metal salts of ligands with LnI2 or by
reductive reaction of lanthanide(III) halides with metallic atoms
[7]. Recently, we have developed a new method for the synthesis
of the organolanthanide(II) complexes by treatments of nitrogen
atom or oxygen atom containing substituents-functionalized in-
the organolanthanide(II) complexes is believed to proceed through
a tandem silylamine elimination [14,15]/homolysis of the Ln–N
bonds reaction.
The fluorenyl ligands have shown much more rich coordination
chemistry with rare earth metals than so far envisioned with group
4 metals [16,17], as a result, the g g g
5 [18], 3 [19,20], 6 [21] bonding
modes of the fluorenyl ligands with rare earth metal have been
documented. Organolanthanide complexes incorporating fluorenyl
moiety such as single-carbon bridged ansa-metallocenes [22,23],
silylene-bridged ansa-metallocenes [24], the class of ‘‘constrained
geometry” half sandwich complexes [19,20], and tetrahydro-2H-
pyranyl- or N-piperidineethyl-functionalized fluorenyl lantha-
nide(II) complexes have been reported [25]. However, the chemis-
try of organolanthanide(II) complexes with other donor group-
functionalized fluorenyl ligands needs further to be explored
[16,17] for the lanthanide(II) complexes containing fluorenyl li-
gand possessing a more higher solubility in nonpolar solvents such
as toluene and hexane than those of complexes with indenyl or
simple cyclopentadienyl ligands [17], which would exhibit a wide
* Corresponding author. Address: Laboratory of Functionalized Molecular Solids,
Ministry of Education, Anhui Laboratory of Molecule-Based Materials, Institute of
Organic Chemistry, School of Chemistry and Materials Science, Anhui Normal
University, Wuhu, Anhui 241000, China. Tel.: +86 553 5910015; fax: +86 553
5910027.
E-mail address: swwang@mail.ahnu.edu.cn (S. Wang).
0020-1693/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2009.12.058

1326
H. Miao et al. / Inorganica Chimica Acta 363 (2010) 1325–1331
application as catalysts for polymerization or as synthetic
materials.
In this paper, we will report the interactions of C5H4NCH2C13H9
with the lanthanide(III) amides [(Me3Si)2N]3Ln(l-Cl)Li(THF)3
(Ln = Yb, Eu, Y, Nd) leading to preparation and characterization of
a series of new organolanthanide(II) and organolanthanide(III)
complexes. The organolanthanide(II) complexes as single-compo-
nal for the paramagnetic property of the complexes. The complexes
were extremely air- and moisture-sensitive solid, they are soluble
in THF, DME, toluene and pyridine, slightly soluble in n-hexane.
Complexes 4 and 6 were additionally characterized by single-crys-
tal X-ray analyses.
X-ray analysis revealed that complex 4 is a monomeric bisfluor-
enyl yttrium chloride, two fluorenyl ligands are
central metal, and the attached pyridine group was g
g
5-bonded with
nent
e
-caprolactone polymerization catalysts will be also reported.
1-coordinated
to the metal, the coordination geometry of the central yttrium
could be described as a distorted trigonal bipyramidal (Fig. 1).
The Y-C(Flu) distances in 4 range from 2.590(4) to 2.896(4) Å, with
an average of 2.765(4) Å (Table 1), which could be compared with
those of the Y–C(Flu) distances of 2.584(7) to 2.885(8) Å found in
2. Results and discussion
2.1. Synthesis and characterization of functionalized fluorenyl
lanthanide complexes
[
g3 1-((3,6-tBu2C13H6)SiMe2NtBu)Y(CH2SiMe2)(THF)2] [20]. The
:g
average Y–C distance found in 4 is slightly longer than that of
2.702(2) in
1-(3,6-tBuFlu)SiMe2NtBu]Y( 1-NC5H6)(py)2
[26], but is comparable to that of 2.784(4) in
((3,6-tBu2C13H6)SiMe2NtBu)Nd(
-Cl)2(THF)2]2 [20] if the ionic radii
Interaction of C13H9Li with 1 equiv. of C5H4NCH2Cl, gave 2-pyr-
idylmethyl substituted fluorenyl compound C5H4NCH2C13H9 (1) in
good yield (Scheme 1). Compound 1 was fully characterized by
spectroscopic methods.
Å
[
g5
:g
g
Å
[ : -
g5 g1
l
difference between the Y3+ and Nd3+ having different coordination
number was taking into account [27]. The Y–N distances in 4 are in
the normal range, but shorter than those of the Y–N distances in
2,6-pyridinediylbis(methylcyclopentadienyl) yttrium complexes
[28–30] for different coordination number and coordination geom-
etry in the complexes.
In contrast to the results that the lanthanide amides
Ln[N(SiMe3)2]3 (Ln = Y, La) and Y[N(SiHMe2)2]3(THF)2 did not react
with the neutral fluorenyl ligands (3,6-tBu2C13H7)SiR2NHtBu
(R = Me, Ph) to afford the silylamine elimination products either
in THF-d8 or in toluene-d8, even on heating above the boiling points
of the solvents for 1 week [20], the reaction of the lanthanide(III)
The fluorenyl moiety was bonded with lithium in g
1 fashion in 6
amides [(Me3Si)2N]3LnIII(
of C5H4NCH2C13H9 (1) at 60–80 °C in toluene produced the corre-
sponding organolanthanide(II) complexes with formula [g5
C5H4NCH2C13H8]2LnII [Ln = Yb (2); Eu (3)] (Scheme 2), and the
interaction of [(Me3Si)2N]3LnIII(
-Cl)Li(THF)3 (Ln = Y, Nd) with 2
l-Cl)Li(THF)3 (Ln = Yb, Eu) with 2 equiv.
(Fig. 2), which was similar to that found in [(3,6-tBu2C13H6)Si-
Me2NtBu]Li2(THF)3 [20], but different to that found in [(3,6-tBu2-
C13H6)SiMe2NtBu]Li(DME) [20] in which the fluorenyl ligand was
bonded with lithium in g5 fashion. The Li–C(Flu) distance of
2.390(4) Å (Table 1) was similar to that of 2.396(6) Å found in
[(3,6-tBu2C13H6)SiMe2NtBu]Li2(THF)3 [20], but is longer than the
average Li–C distance of 2.330(5) Å found in [(3,6-tBu2C13H6)Si-
Me2NtBu]Li(DME) [20] for the different coordination geometry
and steric effects.
:
g1
-
l
equiv. of C5H4NCH2C13H9 (1) in toluene at 80 °C produced, after
recrystallization from n-hexane, the corresponding organolantha-
nide(III) complexes
[ :g
g5 1-C5H4NCH2C13H8]2LnCl [Ln = Y(4),
Nd(5)] (Scheme 2). The formation of complexes 2–5 was suggested
to go through a similar intermediate I via silylamine elimination,
coordination of the substituted pyridine nitrogen atoms to the cen-
tral metal of the intermediate I led to the homolysis of the Ln–N
bonds [8–13] to afford the divalent complexes 2 and 3 when the
lanthanide metals Ln3+/Ln2+ have relative low reductive potentials,
and coordination of the substituted pyridine nitrogen atoms to the
central metal of the intermediate I led to dissociation of LiN-
(SiMe3)2 to produce complexes 4 and 5 when the lanthanide metals
Ln3+/Ln2+ have relative high reductive potentials, indicating reduc-
tive potentials (Ln3+/Ln2+) effects on the reaction pattern. These re-
sults suggested that the bisfluorenyl lanthanide amides of the type
2.2. Ring-opening polymerization of
e-caprolactone
The complexes as single-component catalysts for
e-caprolac-
tone polymerization were examined for ring-opening polymeriza-
tion of lactones providing a convenient route to biodegradable
polyesters which are of interest for a variety of practical applica-
tions. It was found that complexes 2 and 3 exhibited good catalytic
activities on ring-opening polymerization of e-caprolactone both in
toluene and in THF at the temperature range of 0–60 °C. However,
they showed poor catalytic activities in both solvents when the
polymerization reactions were carried out at the temperature be-
low 0 °C. In cases of the monomer/catalysts mole ratio was
800:1, the catalysts also exhibited good to high activities. The re-
sults were listed in Table 2. It was found that complex 3 generally
exhibited a more high catalytic activity on ring-opening polymer-
[
g5 1-C5H4NCH2C13H8]2LnN(SiMe3)2 might not be prepared owing
:g
to bulky steric hinderance of substituted fluorenyl ligand. Com-
plexes 4 and 5 could also be prepared by treatment of 2 equiv. of
6 with 1 equiv. of the corresponding LnCl3 (Scheme 3).
The complexes 2–5 were fully characterized by IR and elemen-
tal analyses. Complexes 2 and 4 were also characterized by 1H
NMR spectra analyses, the diamagnetic properties of complex 2
from the 1H NMR spectra indicated that the central ytterbium me-
tal in complex was in the oxidation state +2. The 1H NMR spectra of
complexes 3 and 5 were not informative due to lack of locking sig-
ization of e-caprolactone in both solvents than complex 2 did. This
result can not be explained by the relative reductive potentials of
Eu3+/Eu2+ and Yb3+/Yb2+, but may be due to the relatively larger io-
nic radii of Eu2+ which may favor the monomer to contact. The
highest catalytic activity of complex 3 has been observed (as high
Et2O
Cl
N
0 o
C
N
Li+
1
Scheme 1.

H. Miao et al. / Inorganica Chimica Acta 363 (2010) 1325–1331
1327
N
III
µ
[(Me3Si)2N]3Ln ( -Cl)Li(THF)3
2
1
toluene
Ln = Y, Nd
Ln = Yb, Eu
2HN(SiMe3)2
N
N
LnIII
N
N(SiMe3)2
Li(thf)x
LnIII
N
N(SiMe3)2
Li(thf)x
Cl
Cl
(I)
(I)
1/2 [N(SiMe3)2]2
LiCl(thf)x
-LiN(SiMe3)2
N
LnII
N
LnIII
Cl
N
N
Ln = Yb(2), Eu(3)
Ln = Y(4), Nd(5)
Scheme 2. The formation pathway for the lanthanide complexes.
as 6.84 ꢀ 106 g polymer/mol catalystꢁh) in toluene at 60 °C as the
solvent/monomer ratio was fixed on 5:1 and the monomer/catalyst
mole ratio on 500:1 which can be comparable to those of ytter-
bium(II) and europium(II) complexes incorporating saturated het-
erocyclic functionalized fluorenyl ligands [25]. The molecular
weights obtained with complexes 2 and 3 (Mn = 2.10–14.96 ꢀ
104) are larger than those obtained with samarium(II) catalytic sys-
tems [31] and the heterometallic catalytic system (9-Me3Si-C13H8-
90AlMe3)2Sm [21]. The highest molecular weight polymer (Mn =
14.96 ꢀ 104) was obtained when the polymerization reaction
was carried out in toluene at 30 °C in the presence of complex 2
as catalyst. The molecular weight distribution of the polymers ob-
tained generally range from 1.09 to 2.50 with only few exceptions
and the lowest molecular weight distribution (Mw/Mn = 1.09) was
observed when the polymerization processes were carried out in
toluene by using complex 3 as catalyst.
3. Experimental
3.1. Materials and methods
All the syntheses and manipulations of air- and moisture-sensi-
tive materials were carried out on the flamed Schlenk-type glass-
ware on a Schlenk line. All solvents were refluxed and distilled
over finely divided LiAlH4 or sodium benzophenone ketyl under ar-
gon prior to use unless otherwise noted. CDCl3 was dried over acti-
vated 4 Å molecular sieves.
e-Caprolactone (e-CL) were dried over
finely divided CaH2, distilled before use. [(Me3Si)2N]3LnIII(
l-
Cl)Li(THF)3 (Ln = Yb, Eu, Y, Nd) were prepared according to re-
ported procedures [8,32]. Elemental analyses were obtained on a
Vario EL III elemental analyzer. IR spectra were recorded on a R
2200 spectrometer (KBr crystal plate, Nujol and Fluoroble mulls).
Melting points were determined in sealed capillaries without

1328
H. Miao et al. / Inorganica Chimica Acta 363 (2010) 1325–1331
N
N
2 n-BuLi / THF
LnCl3 / THF
LnIII
Cl
2
N
Li
N
THF
THF
6
Ln = Y(4), Nd(5)
Scheme 3. The alternative method for preparation of lanthanide chlorides.
Fig. 2. Molecular structure of 6.
3.2. Synthesis of C5H4NCH2C13H9 (1)
To a solution of fluorene (7.27 g, 43.7 mmol) in THF(40.0 mL)
was added a 1.87 M solution of n-BuLi in hexane (23.5 mL,
43.9 mmol) slowly at 0 °C. The reaction mixture was stirred at
room temperature for 12 h, and then the solution was cooled to
0 °C. To the reaction mixture was added C5H4NCH2Cl (5.58 g,
43.7 mmol) in one portion. The reaction mixture was stirred at
room temperature for 12 h, and then was hydrolyzed. The organic
layer was separated and the aqueous layer was extracted with
Fig. 1. Molecular structure of complex 4.
corrections. 1H NMR and 13C NMR spectra were recorded on a Bru-
ker AV-300 NMR spectrometer in C6D6 (benzene-d6) for the lantha-
nide complexes and in CDCl3 for the fluorene. The chemical shifts
for 1H and 13C NMR spectra were reported with a reference to
the internal solvent resonances.
Table 1
Selected bond length (Å) and bond angle (°).
4
6
Y–Cl
2.5363(11)
2.509(3)
2.504(4)
2.712(4)
2.896(4)
2.783(4)
2.845(4)
2.862(4)
2.888(4)
2.786(4)
Y–C(8)
Y–C(9)
Y–C(10)
N(2)–Y–N(1)
N(2)–Y–Cl
N(1)–Y–Cl
2.590(4)
2.705(4)
2.580(4)
172.19(12)
86.02(8)
86.21(9)
C(7)–Li(1)
N(1)–Li(1)
Li(1) –O(1)
Li(1)–O(2)
O(2)–Li(1)–O(1)
O(2)–Li(1)–N(1)
O(1)–Li(1)–N(1)
O(2)–Li(1)–C(7)
O(1)–Li(1)–C(7)
N(1)–Li(1)–C(7)
2.390(4)
2.060(4)
1.960(4)
1.950(4)
100.32(16)
109.75(18)
108.29(18)
124.84(18)
129.07(19)
79.68(12)
Y–N(1)
Y–N(2)
Y–C(2)
Y–C(3)
Y–C(4)
Y–C(5)
Y–C(43)
Y–C(6)
Y–C(7)

H. Miao et al. / Inorganica Chimica Acta 363 (2010) 1325–1331
1329
Table 2
Data for the polymerizations of e-caprolatone (e-CL).
Cat.
Solv.
THF
Mon./cat. (mol/mol)
300:1
Time/min
Temp. (°C)
Mnꢀ10ꢂ4
Mwꢀ10ꢂ4
Mw/Mn
Conv. (%)
Activity ꢀ10ꢂ4
2
0.5
1
3
1.5
5
5
60
30
0
60
30
0
60
30
0
60
30
0
60
30
0
60
30
0
11.57
2.65
4.39
6.24
6.76
7.78
3.03
3.86
5.42
4.20
14.96
4.45
2.10
3.91
5.51
1.99
2.97
3.92
12.62
6.89
8.10
8.92
15.19
10.44
8.75
6.38
6.99
9.18
37.06
9.08
5.49
7.96
8.29
4.57
7.42
7.53
1.09
2.60
1.85
1.43
2.25
1.34
2.89
1.65
1.29
2.18
2.48
2.04
2.62
2.04
1.50
2.29
2.50
1.92
95
>99
94
>99
>99
89
77
24
20
92
94
60
92
28
73
73
69
70
391.10
205.32
61.73
228.25
68.48
58.60
420.61
4.40
500:1
800:1
300:1
500:1
800:1
1
30
30
1
1
30
1
30
30
30
30
30
3.50
Toluene
181.54
191.96
4.09
181.54
3.20
8.38
12.81
9.69
9.82
3
THF
300:1
500:1
0.5
1
1
0.5
1
30
1.5
30
0.5
0.5
3
0.5
1
1.5
3
60
30
0
60
30
0
60
30
60
30
0
60
30
60
30
6.12
8.70
8.56
9.72
7.74
8.48
9.39
3.94
6.76
4.69
7.67
3.46
12.03
13.70
7.53
9.91
1.62
1.22
1.18
2.90
1.44
1.22
1.28
1.65
1.32
1.99
1.51
2.47
1.09
1.09
1.58
92
86
82
89
79
52
95
44
>99
96
93
>99
95
>99
95
379.5
174.4
168.9
600.3
269.6
5.9
345.4
6.2
410.6
394.1
63.5
10.64
10.07
28.24
11.16
10.38
12.06
6.49
800:1
300:1
Toluene
8.93
9.35
11.54
8.54
13.10
14.88
11.26
500:1
800:1
684.8
323.8
365.6
174.5
Condition: solvent/
e-CL (V/V) = 5:1. Activity: g polymer/mol catalyst h.
diethyl ether (2 ꢀ 20.0 mL). The organic fractions were combined
and dried over anhydrous MgSO4, filtered, and evaporated to dry-
ness. The straw colour solids product was obtained (6.64 g, 59%
yield). M.p. 74–76 °C. 1H NMR (300 MHz, CDCl3, 25 °C): d = 8.70
3012 (s), 2951 (s), 2187 (w), 1948 (w), 1589 (s), 1566 (s), 1474
(s), 1447 (vs), 1250 (m), 1153 (w), 995 (w), 937 (m), 837 (m),
783 (m), 741 (vs) cmꢂ1. Anal. Calc. for C38H28N2Yb (685.68): C,
66.56; H, 4.12; N, 4.09. Found: C, 66.69; H, 4.46; N, 3.87%.
(d, 1H, J = 3.8Hz) (a-H C5H4N), 7.75 (d, 2H, J = 7.4Hz) (C13H9),
3.4. Synthesis of [g5 1-(C5H4NCH2C13H8)]2EuII (3)
:g
7.62 (t, 1H) ( -H C5H4N), 7.35 (t, 2H) (C13H9), 7.26–7.02 (m, 6H)
c
(C13H9 + C5H4N), 4.63 (t, 1H, C13H9), 3.21 (d, 2H, J = 7.7Hz)
(C5H4NCH2) ppm. 13C NMR (75 MHz, CDCl3, 25 °C): d = 159.57,
149.23, 146.72, 140.43, 135.94, 126.76, 126.40, 124.34, 124.06,
This complex was isolated as an orange red solid in 54% yield by
treatment of C5H4NCH2C13H9 (0.64 g, 2.50 mmol) with [(Me3Si)2-
N]3EuIII(
l
-Cl)Li(THF)3 (1.12 g, 1.25 mmol) following the similar
procedures as described above for the preparation of 2. M.p.
136–138 °C. IR (KBr, cmꢂ1):
= 3059 (s), 3013 (s), 2962 (s), 2179
121.35, 119.50, 46.87, 42.21 ppm. IR (KBr):
m = 3059 (m), 3012
(m), 2950 (w), 2841 (w), 1937 (w), 1906 (w), 1586 (s), 1566 (s),
1470 (s), 1435 (vs), 1346 (w), 1146 (m), 991 (s), 934 (s), 795 (m),
756 (vs), 729 (vs) cmꢂ1. Anal. Calc. for C19H15N: C, 88.68; H, 5.88;
N, 5.44. Found: C, 88.89; H, 5.89; N, 5.29%.
m
(m), 1952 (m), 1589 (vs), 1566 (vs), 1470 (s), 1443 (vs), 1258 (s),
1150 (m), 995 (m), 941 (m), 864 (m), 783 (s), 737 (vs). Anal. Calc.
for C38H28N2Eu (664.61): C, 68.67; H, 4.25; N, 4.22. Found: C,
68.45; H, 4.40; N, 3.94%.
3.3. Synthesis of [g5 1-(C5H4NCH2C13H8)]2YbII (2)
:g
To a toluene (10.0 mL) solution of C5H4NCH2C13H9 (0.52 g,
2.01 mmol) was added a toluene (50.0 mL) solution of [(Me3Si)2-
3.5. Synthesis of [g5 1-(C5H4NCH2C13H8)]2YCl (4)
:g
N]3YbIII(
l-Cl)Li(THF)3 (0.92 g, 1.00 mmol) at room temperature.
To a toluene (10.0 mL) solution of C5H4NCH2C13H9 (0.61 g,
2.38 mmol) was added a toluene (50.0 mL) solution of [(Me3Si)2-
After the reaction mixture was stirred at room temperature for
6 h, the mixture was then heated at 80 °C for 12 h, the colour of
the solution was gradually changed from yellow to red. The solvent
was evaporated under the reduced pressure. The residue was
washed with n-hexane (10.0 mL). The resulting solid was extracted
with toluene (2 ꢀ 20.0 mL). The toluene solution was combined
and concentrated to about 15.0 mL. The purple–red crystalline so-
lid was obtained by cooling the concentrated solution at 0 °C
(0.29 g, 42% yield). M.p. 176–178 °C. 1H NMR (300 MHz, benzene-
N]3YIII(
l-Cl)Li(THF)3 (0.99 g, 1.19 mmol) at room temperature.
After the reaction mixture was stirred at room temperature for 6
h, the mixture was heated at 80 °C for 12 h. The solvent was then
evaporated under reduced pressure. The residue was washed with
n-hexane (10.0 mL). The resulting solid was extracted with toluene
(2 ꢀ 20.0 mL). The toluene solution was combined and concen-
trated to about 20.0 mL. The pale yellow crystals were obtained
by cooling the concentrated solution at 0 °C for several days
(0.46 g, 61% yield). M.p. 151–153 °C. 1H NMR (300 MHz, ben-
d6): d = 8.50 (s, 2H) (
7.02 (s, 16H) (C13H8), 6.46 (m, 2H) (b-H C5H4N), 6.08 (m, 2H) (b-
H C5H4N), 4.60 (s, 4H) (C5H4NCH2) ppm. IR (KBr): = 3063 (s),
a-H C5H4N), 7.99 (s, 2H) (c-H C5H4N), 7.21–
zene-d6): d = 8.62 (s, 2H) (a-H C5H4N), 7.69 (m, 2H) (c-H C5H4N),
m
7.53–7.02 (m, 16H) (C13H8), 6.70 (m, 2H) (b-H C5H4N), 6.56

1330
H. Miao et al. / Inorganica Chimica Acta 363 (2010) 1325–1331
(m, 2H) (b-H C5H4N), 4.61 (s, 4H) (C5H4NCH2) ppm. IR (KBr):
m
3063
(
SHELXS-97) [33], completed by subsequent difference Fourier syn-
theses, and refined by full-matrix least squares calculations based
on F2
SHELXS-97) [33]. See Table 3 for crystallographic data.
(s), 3013 (s), 2947 (s), 2916 (m), 1628 (m), 1589 (s), 1566 (m), 1474
(m), 1447 (s), 1292 (m), 1153 (w), 995 (w), 937 (w), 795 (m), 756
(s), 737 (s) cmꢂ1. Anal. Calc. for C38H28ClN2Y (637.00): C, 71.65; H,
4.43; N, 4.40. Found: C, 71.28; H, 4.76; N, 4.38%.
(
3.9.
e-Caprolactone polymerization
3.6. Synthesis of [g5
:g
1-(C5H4NCH2C13H8)]2NdCl (5)
e-CL polymerization reactions were performed in a 50.0 mL
Schlenk flask, placed in an external temperature-controlled bath,
on a Schlenk line or in a glovebox. In a typical procedure, the cat-
alyst (20–50 mg) was loaded into the Schlenk flask and the solvent
This complex was isolated as a blue solid in 59% yield by
running reaction of C5H4NCH2C13H9 (0.64 g, 2.48 mmol) with
[(Me3Si)2N]3NdIII(
l
-Cl)Li(THF)3 (1.10 g, 1.24 mmol) following the
procedures described above for the preparation of complex 4.
M.p. 156–158 °C. IR(KBr): = 3063 (s), 3017 (s), 2963 (s), 2924
was added. The e-CL was added through a gastight syringe after the
external bath temperature was stabilized. The polymer product
was precipitated into hydrochloric acid (0.1 M, 50.0 mL), washed
with 0.1 M hydrochloric acid, and then dried to a constant weight
in a vacuum oven at 50 °C. The molecular weights of the polymers
were analyzed by GPC techniques.
m
(m), 1628 (m), 1593 (s), 1570 (m), 1474 (m), 1447 (s), 1261 (m),
1150 (w), 1022 (m), 941 (w), 799 (m), 756 (s), 737 (s) cmꢂ1. Anal.
Calc. for C38H28ClN2Nd (692.34): C, 65.92; H, 4.08; N, 4.05. Found:
C, 65.38; H, 3.87; N, 3.54%.
4. Conclusion
3.7. Synthesis of [g1 1-(C5H4NCH2C13H8)]Li(THF)2 (6)
:g
In summary, a series of organolanthanide(II) and organolantha-
nide(III) complexes with 2-pyridylmethyl substituted fluorenyl li-
gand were synthesized by the interaction of [(Me3Si)2N]3LnIII-
To a solution of C5H4NCH2C13H9 (1) (1.28 g, 4.96 mmol) in THF
at 0 °C was added with stirring 2 equiv of n-BuLi (3.12 mL of a
1.6 M solution in hexane, 4.99 mmol).The reaction mixture was
warmed to room temperature and stirred for 8 h. Volatiles were re-
(l-Cl)Li(THF)3 (Ln = Yb, Eu, Y, Nd) with 2-pyridylmethyl substi-
tuted fluorenyl compound. The formation of the organolantha-
nide(II) complexes was believed through tandem silylamine
elimination/ homolysis of the Ln–N bonds reaction. The synthesis
of the organolanthanide(III) complexes can be accomplished by
silylamine elimination or salt metathesis methods. This work dem-
onstrated that reduction potentials of the Ln3+/Ln2+ have influences
on the reactivity pattern. The results also suggested that the bisflu-
moved under vacuum to yield [g1 1-(C5H4NCH2C13H8)]Li(THF)2 as
:g
a yellow powder (1.92 g, 94%). Crystals of 6 suitable for X-ray dif-
fraction were grown from a THF/hexane mixed solution.
Complexes 4 and 5 can also be prepared in 56% and 53% yields
respectively by reaction of 2 equiv. of 6 with 1 equiv. of the corre-
sponding LnCl3 in THF following the workup procedures similar to
those used for preparation 4.
orenyl
lanthanide
amides
of
the
type
[ : -
g5 g1
C5H4NCH2C13H8]2LnN(SiMe3)2 might not be prepared owing to
bulky steric hinderance of substituted fluorenyl ligand. The results
of the catalytic activities of the organolanthanide(II) complexes
indicated that these complexes exhibited good to high catalytic
activity in either polar solvent THF or aromatic solvent such as tol-
uene. The results also indicated that the temperatures, solvents,
and catalyst loading have influences on the catalytic activities of
catalysts, molecular weights and the molecular weight distribu-
tions of polymers.
3.8. X-ray crystallography
Suitable crystal of complex 4 or 6 was mounted in a sealed cap-
illary. Diffraction was performed on a Siemens SMART CCD-area
detector diffractometer using graphite-monochromated Mo K
radiation (k = 0.71073 Å); temperature 293(2) K; u and
technique; SADABS effects and empirical absorption were applied
in the data corrections. Structure was solved by direct methods
a
x scan
Supplementary material
Table 3
Crystal data and structure refinement for complexes 4 and 6.
CCDC 743156 and 743157 contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
http://www.ccdc.cam.ac.uk/data_request/cif.Supplementary.
4
6
Empirical formula
Formula weight
Crystal system
Space group
a (Å)
C38 H28ClN2Y
636.98
monoclinic
P21/c
10.9547(7)
15.4942(10)
19.4073(12)
92.5960(10)
3290.7(4)
293(2)
C27H26LiNO2
403.43
monoclinic
P21/n
10.9248(12)
19.181(2)
10.9248(12)
95.04
2280.4(4)
293(2)
Acknowledgments
b (Å)
c (Å)
Financial support for this work from the National Natural Sci-
ence Foundation (Grant Nos. 20672002, 20802001, 20832001)
and grants from Anhui province (Nos. TD200707, 2007Z016) are
acknowledged, and Prof. Baohui Du and Jiping Hu’s helps in run-
ning IR and NMR spectra are also grateful.
b (°)
V (Å3)
T (K)
Dcalc (g cmꢂ3
)
1.286
4
1304
1.175
4
856
Z
F(0 0 0)
Reflections collected
28 159
19 529
Number of unique reflections (Rint
Number of parameters
)
7578 (0.032)
380
5225 (0.0295)
281
References
k (Å); Mo K
(mmꢂ1
h Range (°)
Goodness-of-fit (GOF)
a
0.71073
1.881
1.68–27.56
1.108
0.71073
0.073
2.12–27.58
1.044
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