Synthesis, characterization, and reactivity of dinuclear organo-rare-earth-metal alkyl complexes supported by 2-amidate-functionalized indolyl ligands: substituent effects on coordination and reactivity

Article abstract of DOI:10.1039/C9DT00507B

Two series of new dinuclear organo-rare-earth-metal alkyl complexes supported by 2-amidate-functionalized indolyl ligands with different haptic modes were synthesized and characterized. The treatment of [RE(CH₂SiMe₃)₃(THF)₂] with 1 equiv. of 2-(2,6-ⁱPr₂C₆H₃NHC═O)C₈H₅NH (H₂L¹) and 2-(2-^tBuC₆H₄NHC═O)C₈H₅NH (H₂L²) in toluene yielded the dinuclear organo-rare-earth-metal alkyl complexes {[η¹:(μ₂-η¹:η¹)-L¹]RE(CH₂SiMe₃)(THF)₂}₂ [RE = Gd (1a), Dy (1b), Y (1c), Er (1d), and Yb (1e)] and {[η¹:(μ₂-η¹:η¹):η¹-L²]RE(CH₂SiMe₃)(THF)₂}₂ [RE = Gd (2a), Dy (2b), Y (2c), Er (2d), and Yb (2e)] in good yields. When [RE(CH₂SiMe₃)₃(THF)₂] were treated with 2 equiv. of H₂L¹ or H₂L² in THF, the dinuclear organo-rare-earth-metal complexes {(η¹:η¹-HL)[η¹:(μ₂-η¹:η¹):η¹-L]RE(THF)}₂ (1ca: RE = Y, L = L¹; 2ea: RE = Yb, L = L²) were obtained. The complexes could react with small organic molecules such as N,N′-diisopropylcarbodiimide (DIC), phenyl isocyanate, N-methylallylamine, phenylacetylene, pyridine, N-phenylimidazole, or 4-dimethylaminopyridine (DMAP) to yield a series of new complexes with different reactivity patterns along with the reported rare-earth-metal alkyl complexes. In the presence of cocatalysts, these dinuclear organo-rare-earth-metal alkyl complexes could initiate isoprene polymerization with high activity (100% conversion of 2000 equiv. of isoprene in 12 h), yielding polymers with high regioselectivity (1,4 polymers up to 96.1%).

Full text of DOI:10.1039/C9DT00507B

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ISSN 1477-9226
PAPER
Joseph T. Hupp, Omar K. Farha et al.
Efficient extraction of sulfate from water using
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a Zr-metal–organic
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DOI: 10.1039/C9DT00507B
Dalton Transactions
ARTICLE
Synthesis, characterization and reactivity of dinuclear organo-
rare-earth metal alkyl complexes supported by 2-amidate-
functionalized indolyl ligands: substituent effects on coordination
and reactivity
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
Dongjing Hong,a Xiancui Zhu,*a Shaowu Wang,*a,b,c Yun Wei,a Shuangliu Zhou,a Zeming Huang,a
www.rsc.org/
Shan Zhu,a Ruru Wang,a Wenrun Yuea and Xiaolong Mua
Two series of new dinuclear organo-rare-earth metal alkyl complexes supported by 2-amidate functionalized indolyl
ligands in different hapticities were synthesized and characterized. Treatment of [RE(CH2SiMe3)3(THF)2] with 1 equiv of 2-
(2,6-iPr2C6H3NHC=O)C8H5NH (H2L1) and 2-(2-tBuC6H4NHC=O)C8H5NH (H2L2) in toluene gave the dinuclear organo-rare-earth
metal alkyl complexes {[η1:(μ2-η1:η1)-L1]RE(CH2SiMe3)(THF)2}2 [RE = Gd(1a), Dy(1b), Y(1c), Er(1d), Yb(1e)] and {[η1:(μ2-
η1:η1):η1-L2]RE(CH2SiMe3)(THF)2}2 [RE = Gd(2a), Dy(2b), Y(2c), Er(2d), Yb(2e)] in good yields. When [RE(CH2SiMe3)3(THF)2]
were treated with 2 equiv of H2L1 or H2L2 in THF, the dinuclear organo-rare-earth metal complexes {(η1:η1-HL)[η1:(μ2-
η1:η1):η1-L]RE(THF)}2 (1ca: RE = Y, L = L1; 2ea: RE = Yb, L = L2) were obtained. The complexes could react with small organic
molecules such as N,N'-diisopropylcarbodiimide (DIC), phenylisocyanate, N-methylallylamine, phenylacetylene, pyridine,
N-phenylimidazole or 4-dimethylaminopyridine (DMAP) to give a series of new complexes with findings of different
reactivity patterns with reported rare-earth metal alkyl complexes. In the presence of co-catalysts, the dinuclear organo-
rare-earth metal alkyl complexes could initiate the isoprene polymerization with a high activity (100% conversion of 2000
equiv of isoprene in 12 h) producing polymers with high regioselectivity (1,4- polymers up to 96.1%).
centers and different kind of high efficient and high regio- and
stereoselectively isoprene polymerization catalysts.4-6 In
addition, there were other very valid amidate ligands derived
Introduction
Indole and its derivatives, as an alternative indenyl ligand,
have been proverbially used in transition organometallic
chemistry with findings of various hapticity modes such as η1,
η2, η3, η5, η6, etc, and high active catalysts for small molecules
transformations.1-5 Recently, we developed several kinds of
rare-earth metal mononuclear and dinuclear complexes
bearing different functionalized indolyl ligands with findings of
new bonding modes of the ligands with rare-earth metal
from amides, which were found plenty of coordination
chemistry including monodentate: O-bond or N-bond with
metal center,7 bridging modes,8 and chelating forms,9-10
resulting in different kinds of complexes. These complexes
supported by the amidate ligands were found to display good
catalytic activity for norbornene polymerization,11 three-
component Strecker reaction12 and symmetric intermolecular
Heck Reaction,13 hydroboration of unactivated imines and
nitriles,14 etc.
a. Laboratory of Functional Molecular Solids, Ministry of Education, Anhui
Laboratory of Molecule-Based Materials, College of Chemistry and Materials
Science, Anhui Normal University, Wuhu, Anhui 241002, P. R. China.
b. College of Biological and Chemical Engineering, Anhui Polytechnic University,
Wuhu, Anhui 241000, P. R. China.
The synthesis of complexes supported by amidate ligands
has been developed through isocyanate insertion reaction,9d,15
single electron reductive coupling reaction16 and direct
reaction of amidate ligands with metal complexes.17 Although
the chemistry of transition metal complexes with amidate
ligands was well developed, apart from those of derived from
insertion reaction of corresponding compounds with
isocyanates, the chemistry of rare-earth metal complexes with
target amidate ligands is far less be documented.15a-b,18 To
integrate the multiple hapticitic capabilities of both indolyl and
amidate ligands, and as our continuous interest in designing
multinuclear catalysts,4-6 the 2-amido functionalized indolyl
compounds were designed and synthesized as pro-ligands,
c. State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic
Chemistry, Chinese Academy of Sciences, Shanghai 200032, P. R. China.
† E-mail: swwang@mail.ahnu.edu.cn; wsw@ahpu.edu.cn (Wang, S.)
Electronic Supplementary Information (ESI) available: CCDC Nos 1574045-1574047
for 1a
1574058 for 1ea
1574066 for 3a contain the supplementary crystallographic data for this paper.
-
1c; 1574048-1574050 for 1ca
-
1cc; 1574051-1574052 for 1d
-
1e; 1574053-
-
1ef; 1574059-1574063 for 2a
-
2e; 1574064-1574065 for 2ea
-
2eb;
These
data
can
be
obtained
free
of
by
charge
via
www.ccdc.cam.ac.uk/data_request/cif,
or
emailing
data_request@ccdc.cam.ac.uk, or by contacting The Cambridge Crystallographic
Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
NMR spectra for characterization of the new ligands of H2L1 H2L2, complexes 1c
, ,
1cb and 1cc (PDF). See DOI: 10.1039/x0xx00000x
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ARTICLE
Journal Name
which
interacted
with
rare-earth
metal
alkyls
View Article Online
DOI: 10.1039/C9DT00507B
RE(CH2SiMe3)3(THF)x, producing different ligated rare-earth
metal complexes depending on substituents on the amides.
The catalytic activity of these complexes in the presence of co-
catalysts, and their reactivity toward small organic molecules
were investigated with findings of different activities from
those reported in the literatures.19 In this paper, we will report
the results.
Results and discussion
Synthesis and characterization of organo-rare-earth metal alkyl
complexes supported by 2-amidate indolyl ligands. The pro-
ligands H2L1 and H2L2 can be obtained by the reactions of the
appropriate carbonyl chlorides with corresponding amines in
90% yields. The pro-ligands were fully characterized by
spectroscopic methods and HR-MS analyses. Treatment of
[RE(CH2SiMe3)3(THF)2] with 1 equiv of H2L1 and H2L2 in toluene
gave the dinuclear organo-rare-earth metal alkyl complexes
Figure 1. Representative ortep diagram of complexes 1a-1e.
Thermal ellipsoids are set at 30% probability level. All
hydrogen atoms and Dipp (2,6-diisopropylphenyl) groups on
N2 and N2(i) are omitted for clarity.
1a
-1e and 2a-2e in good yields (Scheme 1). All the dinuclear
organo-rare-earth metal alkyl complexes 1a
-
1e and 2a 2e were
-
fully characterized by spectroscopic methods, elemental
analyses, and the structures of these complexes were
1
determined by single-crystal X-ray diffraction. H NMR spectra
showed the signals centered at -0.34 ppm which can be
assigned to the resonances of the protons of the -CH2- group
of the trimethylsilylmethyl group for complex 1c in C6D6 at
25 °C. The signals centered at 165.6 ppm in 13C NMR spectra
were assigned to the resonances of the carbon atoms of the
amidate group, the signals centered at 25.1 ppm were
assigned to the resonances of the carbon atoms of the
trimethylsilylmethyl group coupled to the yttrium nucleus with
JY-C = 50 Hz.
Figure 2. Representative ortep diagram of complexes 2a-2e.
Thermal ellipsoids are set at 30% probability level. All
hydrogen atoms and o-tBuC6H4 groups on N2 and N2(i) are
omitted for clarity.
X-ray analyses revealed that the indole units and the amides
groups of H2L1 or H2L2 were deprotonated by the metal alkyl
CH2SiMe3 moiety, affording a dianionic species that bridges
two rare-earth metal alkyl units in η1:(μ2-η1:η1) or η1:(μ2-
η1:η1):η1 bonding modes forming the dinuclear organo-rare-
earth metal alkyl complexes with central symmetry (Figure 1
and Figure 2), in which the oxygen atoms of the ligands
adopted μ2 bonding modes coordinated with two metal
coordinated by the carbon atom of the trimethylsilylmethyl
group CH2SiMe3 and the nitrogen atom of indolyl moiety and
the oxygen atom of amidate group and the oxygen atoms of
THF adopting a six-coordinate distorted octahedral geometry.
While in the complexes 2a-2e, the amidate fragments of the
ligands adopted the chelate motifs with the oxygen atoms
taking bridged coordination modes, while the nitrogen atoms
of the amidate group coordinated to one of rare-earth metal
ions. This coordination mode is different from those found in
centers. The central metals of the complexes 1a-1e
complexes 1a-1e, and those found in the literatures with
comparison the distances of the nitrogen atom of the amidate
to central metal ion.20 These results suggest that substituents
on the nitrogen atom of the amidate group can make a
significant influence on the coordination modes of the amidate
motifs with the central rare-earth metal.
From Table 1, it was found that the bond lengths of RE-
CCH2SiMe3, RE-N1 and RE-O1 in complexes 1a-1e and 2a-2e are
decreased as ionic radii decrease from Gd3+ to Yb3+, these
results are in good agreement with the lanthanide contraction.
The distances of RE1-N2(i) [3.004(3) Å for 1a, 3.051(4) Å for 1b
,
3.069(6) Å for 1c, 3.089(4) Å for 1d, 3.176(4) Å for 1e], found in
Scheme 1. Synthesis of the dinuclear complexes 1a
2e
-1e and 2a-
complexes 1a
-
1e are significantly longer than the
.
2 | J. Name., 2012, 00, 1-3
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Journal Name
Table 1. Selected bond lengths (Å) and angles (
ARTICLE

) of complexes characterized by spectroscopic methods, elemental analyses,
View Article Online
and X-ray crystallographic analyses. X-rDayOI:a1n0a.1l0y3s9e/sC9iDnTd0ic0a5t0e7dB
1a
-1e and 2a
-2e
.
that the complexes contain two chelate amidate functionalized
1a
1b
1c
1d
1e
RE1-O1
RE1-N1
RE1-N2(i)dist.
RE1-C22
C9-O1
C9-N2
N1-RE1-O1
N2-C9-O1
2.298(3)
2.410(4)
3.004(3)
2.416(7)
1.338(5)
1.283(6)
66.59(12)
116.1(4)
2a
2.324(2)
2.398(3)
2.770(3)
2.424(4)
1.320(4)
1.292(4)
66.39(9)
114.4(3)
2.284(3)
2.371(4)
3.051(4)
2.388(8)
1.333(6)
1.276(7)
67.23(13)
116.1(5)
2b
2.297(2)
2.364(2)
2.783(2)
2.413(3)
1.333(4)
1.288(3)
67.07(7)
114.5(3)
2.269(4)
2.367(6)
3.069(6)
2.376(6)
1.336(7)
1.298(8)
67.97(17)
115.0(6)
2c
2.279(2)
2.367(2)
2.790(2)
2.412(3)
1.324(3)
1.288(3)
67.43(7)
114.5(3)
2.259(3)
2.331(5)
3.089(4)
2.367(7)
1.330(6)
1.283(6)
68.61(15)
116.9(5)
2d
2.271(2)
2.341(3)
2.811(3)
2.395(4)
1.329(4)
1.287(4)
67.75(8)
114.6(3)
2.237(2)
2.315(3)
3.176(4)
2.326(5)
1.347(4)
1.262(5)
70.02(10)
117.6(3)
2e
2.254(4)
2.304(6)
2.888(6)
2.346(9)
1.320(9)
1.298(9)
68.3(2)
indolyl ligands and two terminal amidate functionalized indolyl
ligands. It is found that the RE-Namidate, C-O, and C-Namidate
distances, and the O-C-N angles can be compared with those
found in
2 but shorter than those found in 1, suggesting that
the amidate motifs in 1ca and 2ea adopted chelate form
having oxygen atoms in bridging form. The results indicated
that coordination environment have a great impact on
bonding form of the amidate motifs.
RE1-O1
RE1-N1
RE1-N2(i)
RE1-C20
C9-O1
C9-N2
N1-RE1-O1
N2-C9-O1
114.6(7)
corresponding bond lengths of RE1-N2(i) [2.770(3) Å for 2a
,
2.783(2) Å for 2b, 2.790(2) Å for 2c, 2.811(3) Å for 2d, 2.888(6)
Å for 2e], which are also significantly longer than those found
in {
L
Y[N(SiMe3)2]·THF}2 (H2L = N,N′-(cyclohexane-1,2-diyl)bis(4-
Yb[N(SiMe3)2]·THF}2
tert-butylbenzamide), 2.443(6) Å)20a
,
{L
(
H2L = N,N′-(cyclohexane-1,2-diyl)bis(4-tert-butylbenzamide),
2.405(5) Å)20b, [Yb3L6]·2C7H8 (
L
= 2,6-iPr2C6H3NC(O)Ph, 2.443(4)
Å, 2.445(5) Å, 2.493(4) Å)20c indicating substituents on the
amidate motifs have a great effect on bond length. It is also
found that the distances and bond lengths of RE1-N2(i) in
Scheme 2. Synthesis of complexes 1ca and 2ea
.
complexes
1 and 2 increased as the ionic radii decreased from
Gd3+ to Yb3+, indicating that the steric effects increase will
result in the weak interactions between N2 and the rare-earth
metal as the ionic radii decrease. The steric effects not only
have influence on the bond lengths of the RE-X [X = O1, N2],
but also have an impact on the C-O, C-N bond lengths and the
O-C-N angles of the amidate motifs. For example, the C-O
bond lengths in
while the C-N bond distances in
those found in . These results indicated that the O-C-N
moieties in are more delocalized than those in . It is found
that the O-C-N angles of 115.0(6) to 117.6(3) found in from
gadolinium to ytterbium complexes are larger than the angles
of 114.4(3) to 114.6(7) found in . The O-C-N angles found in
are very close to the chelate form found in the tantalum
amidate complexes (average 113.5(2)
),21 they are also close
to the angles found in the bridged bis(amidate) rare-earth
metal amides (average 115.5(4)
).20 The results of C-O, C-N
bond lengths and RE1-N2(i) distances and the O-C-N angles
suggested that the amidate moieties in complexes take the
1
are generally longer than those found in
2,
1
are generally shorter than
2
2
1
Figure 3. ORTEP diagram of complex 1ca. Thermal ellipsoids
are set at 30% probability level. All hydrogen atoms and Dipp
groups on N2 and N2(i) are omitted for clarity.


1


2
2


2
chelate coordination sphere having oxygen atom adopted
bridge form with the rare-earth metals. The O-C-N angles
found in
monodentate amidate ligated tantalum complex21 and those
found in
1 fall between that 127.34(18) found in the
2
.
Figure 4. ORTEP diagram of complex 2ea. Thermal ellipsoids
are set at 30% probability level. All hydrogen atoms and o-
tBuC6H4 groups on N2 and N2(i) are omitted for clarity.
In order to investigate the effect of the coordination
environment on the bonding modes of the amidate with the
central metals, different ratio reactions of H2L1 or H2L2 with
[RE(CH2SiMe3)3(THF)2] were carried out. Treatment of
[RE(CH2SiMe3)3(THF)2] with 2 equiv of H2L1 or H2L2 in THF
produced the dinuclear organo-rare-earth metal complexes
1ca and 2ea in good yields (Scheme 2). They were fully
Reactivity study. With above new alkyl complexes in hand,
their reactivity properties towards small molecules were
explored firstly. Fortunately, several definite results were
obtained (Scheme 3). The reaction of complex 1c with 2 equiv
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ARTICLE
Journal Name
Table 2. Selected bond lengths (Å) and angles (

) of complexes steric bulky effects can partially be proved by theVrieewsAurltticloe fOntlhinee
DOI: 10.1039/C9DT00507B
1ca and 2ea
.
reaction of phenylacetylene with 1e, which produced the
terminal bonding alkynyl ytterbium complex 1ea (Scheme 3,
Figure S41 in ESI). This terminal bonding mode is different
1ca
2ea
2.319(6)
2.534(6)
2.307(6)
2.268(4)
2.328(4)
2.247(4)
1.328(8)
Y1-N1
Y1-N2(i)
Y1-N3
Y1-O1
Y1-O1(i)
Y1-O2
C9-O1
C9-N2
C30-O2
C30-N4
N2-C9-O1
N4-C30-O2
2.345(3)
2.650(3)
2.340(3)
2.307(2)
2.316(2)
2.332(3)
1.321(4)
1.290(5)
1.274(5)
1.331(5)
114.8(3)
120.8(4)
Yb1-N1
Yb1-N2(i)
Yb1-N3
Yb1-O1
Yb1-O1(i)
Yb1-O2
C9-O1
from the mostly reported alkynyl rare-earth metal complexes
in which alkynyl adopted bridged bonding mode,24 indicating
steric effects of the ligands. It has been reported that rare-
earth metal alkyl complexes can react with pyridine or
C9-N2
1.286(8)
C28-O2
C28-N4
N2-C9-O1
N4-C28-O2
1.275(10)
1.329(9)
113.6(6)
121.5(7)
imidazole derivatives to produce the C-H activation
products,19,25 however, when complex 1e was treated with 2
equiv of pyridine or N-phenylimidazole afforded the ligands
exchange products 1eb and 1ec (Scheme 3), no C-H bond
activation was observed as reported in literatures.25 These
results can be attributed to ligands steric effects which prevent
the C-H bond of the pyridine or N-phenylimidazole from
interaction with the alkyl groups of the complexes, and the
activity of the alkyl groups may also be responsible for the
results. The molecular structures of 1eb and 1ec are given in
Figure S42 and Figure S43 in the ESI. From the structural data
of DIC (diisopropylcarbodiimide) in toluene at room
temperature took place rapidly. Bis(amidinate)-ligated
complex 1cb (Scheme 3), formed through carbodiimide
insertion into the Y-CCH2SiMe3 bonds in 1c 22
was isolated as a
,
white crystalline solid in 33% yield from a mixture of THF/n-
hexane solution at -30 °C. The reaction of complex 2e with 2
equiv of phenylisocyanate in toluene at room temperature
afforded the bis(amidate) ligated complex 2eb (Scheme 3) as a
red crystalline solid in 48% yield through isocyanate insertion
of all the above reactions produced complexes 1cb
1eb 1ec, and 2eb, it was found that the amidate motifs
adopted bridged ligation when the Ar is 2,6-
diisopropylphenyl, and the amidate moiety took the chelate
, 1cc, 1ea,
into the Yb-CCH2SiMe3 bonds in 2e 10
. The molecular structures of
,
1cb and 2eb are given in Figure S39 and Figure S53 in the ESI.
From the structural data of 1cb and 2eb, it can be concluded
O
that the amidate motifs connected to the indolyl rings adopted form with O bridge ligation when the Ar is 2-tert-butylphenyl.
the same coordination forms as those found in 1c and 2e
,
When 1e was treated with 4 equiv of DMAP in THF at room
temperature for 3 h to give the only ligands exchange product
1ed (Scheme 4, Path A). Complex 1ed could also be
synthesized by treatment of 3a (X-ray identified) with 1 equiv
of H2L1 in toluene at room temperature (Scheme 4, Path B), no
C-H bond activation was found from the two synthetic paths,
which is different from the reported reactivities of the earth
metal alkyl complexes with pyridine.25 It is worth mentioning
that the -CH2SiMe3 group lied in an equatorial position of the
distorted octahedral geometry in complex 1e, but it was
changed to the axial position in complex 1ed. This result
suggested that the strong donor ligand DMAP could change
the coordination geometry of the rare-earth metal complex.
The molecular structures of 3a and 1ed are given in Figure S54
and Figure S44 in the ESI. Unexpectedly, when the
respectively. While the amidate moiety in 2eb formed through
insertion reaction took the chelate form bonded with the
central metals. Then, the reactivities of the above alkyl
complexes with secondary amine bearing C=C double bond
and the terminal alkyne with sp C-H bond were examined. The
reaction of complex 1c with 2 equiv of N-methylallylamine in
toluene at ambient temperature was found to form the allyl
amido complex via N-H activation (Scheme 3, Figure S40 in ESI).
This observation is different from those of the reactions of
group IV metal complexes with N-methylallylamine, which
produced the azabutadiene complex via activation of the N-H
bond and C-H bond neighbour to the nitrogen atom.23 This
difference could be attributed to the steric bulky in 1c which
prevents the C=C double bond from the central metal. The
Ar
O
Ar
N
Ar = 2,6-iPr2C6H3
O
N
O
Y
Si
N
O
N
Yb
Ar = 2,6-iPr2C6H3
RE = Y
RE = Yb
N
Yb
O
O
N
N
2eq. PhCCH
THF, 60 °C, 12 h
-2 SiMe4
O
N
Y
N
O
2 eq. C(=NiPr)2
Toluene, r.t., 4 h
-2 THF
Ar
N
1
N
O
Ar
N
Si
O
N
O
Ar
indolyl
RE
1ea
1cb
Ar
Ar
O
Ar
N
Si
N
O
O
N
Si
N
N
Y
N
Ar = 2,6-iPr2C6H3
RE = Yb
N
Ar = 2,6-iPr2C6H3
RE = Y
N
O
N
O
O
N
Yb
O
O
O
RE
O
Yb
O
Y
N
RE
O
2 eq. Pyridine
Toluene, r.t., 3 h
-2 THF
2 eq. MeNHCH 2CH=CH2
Toluene, r.t., 4 h
-2 SiMe4
O
N
N
O
O
N
N
Si
N
Ar
Si
O
Ar
Ar
Ar
1eb
1cc
2
Ar
N
O
Ar
indolyl
Yb
O
O
Si
N
Si
N
N
O
Ar = 2-tBuC6H4
O
N
N
Ar = 2,6-iPr2C6H3
RE = Yb
N
N
N
Yb
RE = Yb
O
N
Yb
Yb
O
O
Yb
2 eq. PhNCO
Toluene, r.t., 3 h
-2 THF
N
O
O
N
N
Si
2 eq. N-Phenylimidazole
Toluene, r.t., 3 h
-2 THF
N
N
Ar
2eb
Si
O
Ar
1ec
4 | J. Name., 2012, 00, 1-3
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Journal Name
Scheme 3. Reactions of dinuclear organo-rare-earth metal alkyl complexes with small organic molecules.
ARTICLE
View Article Online
DOI: 10.1039/C9DT00507B
Scheme 4. Synthesis of complexes 1ed
-1ef.
N-methylimidazole or N-benzylimidazole instead of DMAP was
Catalytic activities of the dinuclear organ-rare-earth alkyl
used to treat with Yb(CH2SiMe3)3(THF)2 firstly followed by complexes towards isoprene polymerization. As reported, the
treatment with H2L1, the non-centrosymmetrical complexes mono- and dinuclear organo-rare-earth alkyl complexes
1ee and 1ef were isolated (Figure 5 for 1ee). Again, no C-H exhibited an excellent catalytic activity for isoprene
bond activation was found from the two synthetic reaction polymerization in the presence of cocatalyst.4-6 With the above
processes. From the structural data, it was found that the two new dinuclear organ-rare-earth alkyl complexes in hand, their
metal centers have different coordination sphere, one of Yb3+ catalytic activities for the isoprene polymerization were
ion was coordinated by two N atoms of the indolyl moiety, two investigated. Representative data are summarized in Table 3
and Table 4.
O atoms of the bridged amidate groups, three N atoms of the
imidazole ligands. Another Yb3+ ion was coordinated by two
amidate groups in chelated form, one O atom of the amidate
group, one N atom of the indolyl ring, one N atom of the
imidazole ring. It is also found that the amidate groups also
adopted different coordination modes with the central metals,
two amidate groups took chelate form with O bridged two
metal centers, the other amidate group only has the O atom
bonded with metal center. The molecular structure of 1ef is
given in Figure S46 in the ESI. All complexes mentioned above
can be stored as solids for months without any indication of
decomposition under inert conditions, but they decompose
immediately in the presence of oxygen or atmospheric
moisture.
None of the above dinuclear organ-rare-earth alkyl
complexes alone could initiate the polymerization of isoprene,
and the binary systems of complexes/AlR3
complexes/[Ph3C][B(C6F5)4] also could not catalyze the
isoprene polymerization. Fortunately, the ternary systems of
complexes/[Ph3C][B(C6F5)4]/AlR3 could initiate the isoprene
polymerization.
or
The data in Table 3 are the representative results of
polymerization of isoprene based on complexes 1a
catalysts. The ternary systems
complex/[Ph3C][B(C6F5)4]/AlR3 could not initiate the isoprene
polymerization when the AlR3 is AlMe3 or AlEt3 (Table 3,
-
1e as pre-
of
entries
1
and
2).
The
ternary
system
complex/[Ph3C][B(C6F5)4]/AliBu3 could polymerize the isoprene
in chlorobenzene, but the polymerization did not happen in
other solvents such as toluene or dichloromethane (Table 3,
entries 5 and 6). With lengthening the polymerization time,
the 1,4-content and the molecular weight were increased
(Table 3, Entries 3 and 4). The 1,4-content and the molecular
weight of polymers decreased when the [PhMe2NH][B(C6F5)4]
was used as co-catalyst instead of [Ph3C][B(C6F5)4] (Table 3,
comparison the data of entries 4 and 7). It is found that the
metal centers have a great influence on the activity and
regioselectivity of the ternary catalyst systems (Table 3, entries
4, 10, 11, 13 and 14). With decrease of the ionic radii of the
central metal ions, the catalytic activity, 1,4- content and the
molecular weight were decreased, but the Gd analogue was
abnormal, which made the variation trend look like a parabola.
Unfortunately, ytterbium analogue 1e showed no catalytic
Figure 5. ORTEP diagram of complex 1ee. Thermal ellipsoids
are set at 30% probability level. All hydrogen atoms and Dipp
group on N2 and N4 are omitted for clarity.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
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ARTICLE
Journal Name
activity for the isoprene polymerization under the same reported, which is probably due to the Yb3+/Yb2+ redox activity
View Article Online
DOI: 10.1039/C9DT00507B
in the presence of aluminum alkyls.4-6,26
conditions. This result is consistent with previously literature
Table 3. Representative data of polymerization of isoprene based on complexes 1a
-
1e as pre-catalystsa
Structurec
3,4
[IP]/[Cat.
]
Entry
Cat.(Sol.)
AlR3
t(h)
Conv.(%)b
Mnd(×10-4) PDId
1,4
/
/
77.4
88.6
/
1
2
3
4
1b(C6H5Cl)
1b(C6H5Cl)
1b(C6H5Cl)
1b(C6H5Cl)
1b(toluene)
1b(DCM)
1b(C6H5Cl)
1b(C6H5Cl)
1b(C6H5Cl)
1a(C6H5Cl)
1c(C6H5Cl)
1c(C6H5Cl)
1d(C6H5Cl)
1e(C6H5Cl)
500:1
500:1
500:1
500:1
500:1
500:1
500:1
1000:1
2000:1
500:1
500:1
1000:1
500:1
500:1
AlMe3
AlEt3
12
12
6
0
0
100
100
0
/
/
/
/
/
/
AliBu3
AliBu3
AliBu3
AliBu3
AliBu3
AliBu3
AliBu3
AliBu3
AliBu3
AliBu3
AliBu3
AliBu3
22.6
11.4
/
25.3
36.8
/
1.68
1.67
/
12
12
12
12
12
12
12
12
12
12
12
5
6
0
/
/
/
/
7e
8
100
100
100
100
100
66
45
0
76.9
74.3
68.8
75.3
78.1
77.8
77.2
/
23.1
25.7
31.2
24.7
21.9
22.2
22.8
/
33.9
26.0
48.3
25.2
31.2
35.5
16.7
/
1.68
1.82
1.90
1.91
1.47
1.95
1.32
/
9
10
11
12
13
14
aGeneral conditions: [Cat.] = 10 μmol, [Cat.]:[Ph3C][B(C6F5)4]:[AlR3] = 1:1:2, room temperature, Vol(IP):Vol(Sol.) = 1:10, charging
sequence: [Cat.], [B], [Al], [IP]. bDetermined by the weight of polymer materials in comparison with that of monomer.
cDetermined by 1H and 13C NMR spectrosocopy in CDCl3. dDetermined by means of GPC against polystyrene standards in THF at
35 °C, PDI = polydispersity index. e[B] = [PhMe2NH][B(C6F5)4].
Table 4. Representative data of polymerization of isoprene based on complexes 2a
-
2e as pre-catalystsa
Structurec
Entry
Cat.(Sol.)
[IP]/[Cat.]
AlR3(equiv) t(h) Conv.(%)b
Mnd(×10-4) PDId
1,4
3,4
1
2
2b(C6H5Cl)
2b(C6H5Cl)
2b(toluene)
2b(toluene)
2b(toluene)
2b(toluene)
2a(toluene)
2b(C6H5Cl)
2b(toluene)
2b(toluene)
2b(toluene)
2b(toluene)
2c(toluene)
2c(toluene)
2c(toluene)
2b(C6H5Cl)
2b(toluene)
2b(C6H5Cl)
2a(C6H5Cl)
2c(C6H5Cl)
500:1
500:1
500:1
500:1
1000:1
1500:1
500:1
500:1
500:1
500:1
1000:1
1500:1
500:1
1000:1
1500:1
500:1
500:1
500:1
500:1
500:1
AlMe3(5)
AlMe3(20)
AlMe3(20)
AlMe3(20)
AlMe3(20)
AlMe3(20)
AlMe3(20)
AlEt3(5)
AlEt3(5)
AlEt3(5)
AlEt3(5)
AlEt3(5)
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
79
84.6
94.6
96.1
95.2
95.6
94.8
94.8
85.3
86.7
89.4
91.4
86.6
87.5
82.0
84.9
83.9
81.8
78.2
80.4
75.9
15.4
5.4
3.9
4.8
4.4
5.2
5.2
14.7
13.3
10.6
8.3
13.4
12.5
18.0
15.1
16.1
18.2
21.8
19.6
24.1
13.5
13.5
8.5
8.1
9.4
12.9
8.4
18.5
6.2
2.82
1.58
1.57
1.55
2.84
1.99
2.26
1.77
1.73
2.50
2.38
2.53
2.28
3.16
2.51
2.86
5.93
2.08
2.13
3.45
100
100
100
100
100
79
99
99
100
97
91
99
93
95
74
100
31
62
95
3
4e
5
6
7
8
9
10e
11e
12e
13e
14e
15e
16
17
18e
19
20
8.1
19.6
27.1
4.2
13.9
19.5
10.2
8.4
12.9
17.1
6.9
AlEt3(5)
AlEt3(5)
AlEt3(5)
AliBu3(5)
AliBu3(5)
AliBu3(5)
AliBu3(5)
AliBu3(5)
aGeneral conditions: [Cat.] = 10 μmol, [Cat.]:[Ph3C][B(C6F5)4] = 1:1, room temperature, Vol(IP):Vol(Sol.) = 1:10, charging sequence:
b
c
1
[Cat.], [B], [Al], [IP]. Determined by the weight of polymer materials in comparison with that of monomer. Determined by H
and 13C NMR spectrosocopy in CDCl3. Determined by means of GPC against polystyrene standards in THF at 35 °C, PDI =
d
polydispersity index. e[B] = [PhMe2NH][B(C6F5)4].
Table 4 gave the representative results of polymerization of complexes 1a
-
1e. In case of different AlR3 used in catalytic
isoprene based on complexes 2a-2e as pre-catalysts. It is found systems of 2a-2e, 20 equiv of AlMe3 were required for high
that they displayed prominent differences on catalytic conversion of monomer, only 5 equiv of AlEt3 or AliBu3 could
activities on the isoprene polymerization from the complexes reach the high conversion, but producing relatively low 1,4-
1a
display activities for the isoprene polymerization for the series catalyst (Table 4); (2) Toluene and chlorobenzene are good
of complexes 2a 2e (Table
2e (Table 4), while only AliBu3 as co-catalyst solvents for the polymerization for the complexes 2a
displayed activity for the isoprene polymerization for the 4), while only chlorobenzene can be solvent for the
-1e did: (1) Different aluminum alkyls as co-catalysts could regioselectivity polymers than those with AlMe3 as the co-
-
-
6 | J. Name., 2012, 00, 1-3
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Dalton Transactions
Journal Name
polymerization for the complexes 1a
best co-catalyst for the 1,4-regioselectively polymerization universality as supporting ligands for construction of
producing polymers having 1,4-regioselectivity as high as multinuclear organometallic complexes as catalysts for the
96.1%. For complex 2b, when the AlR3 is AlMe3, decrease the regioselectively polymerization of olefins. Further work in this
ARTICLE
-
1e; (3) The AlMe3 is the amidate functionalized electron-rich indolyl ligands might have
View Article Online
DOI: 10.1039/C9DT00507B
field is now in progress.
ratio of [Cat.]/[AlMe3] resulted in the increase of 1,4-content
of the polymers from 84.6% to 94.6%, and resulted in a narrow
molecular weight distribution (Table 4, entries 1 and 2). The
1,4-regioselectivity is only slightly different when the
polymerization was carried out in toluene or in chlorobenzene
(Table 4, entries 2 and 3). The 13C-int NMR spectra showed
that the selectivity of the 1,4-cis-selectivity were significant
enhanced from 37.8% in toluene to 58.6% in chlorobenzene
(see ESI). This result is consistent with previously literature
reported that the 1,4-cis-component is propitious to the
coordination ability of solvents (the less coordinated solvent
chlorobenzene vs toluene).27 The borate [PhMe2NH][B(C6F5)4]
and [Ph3C][B(C6F5)4] exhibited a similar activity for the
polymerization producing polymers having very close 1,4-
regioselectivity and molecular weight (Table 4, entries 3 and 4).
With increase of the ratio of [IP]/[Cat.], the 1,4-regioselectivity
decreased and the molecular weight increased (Table 4,
entries 3, 5 and 6 for complex 2b; and entries 13-15 for
complex 2c). In comparison, the molecular weights of the
Experiment Section
General Procedures. All syntheses and manipulations of air- and
moisture-sensitive materials were performed under a dry and
oxygen free argon atmosphere using standard Schlenk
techniques or in an argon-filled glovebox. All solvents such as
THF, toluene and n-hexane were distilled over sodium
benzophenone ketyl under argon prior to use unless otherwise
noted. Dichloromethane and chlorobenzene were distilled
over CaH2 under argon prior to use. B(C6F5)3, [Ph3C][B(C6F5)4]
and [PhNMe2H][B(C6F5)4] were purchased from STREM and
used as received. AlMe3, AlEt3, and AliBu3 were purchased
from Sigma-Aldrich, and used as received. Isoprene was
purchased from TCI, dried with CaH2, and distilled over CaH2
before use. Elemental analyses data were obtained on an
Model Vario EL Series III elemental analyzer. H NMR and 13C
1
NMR spectra for analyses of compounds were recorded on a
Bruker Model AV-300 or AV-500 NMR spectrometer (300 or
polymers catalyzed by the series of complexes 1a
significantly larger than those catalyzed by the series of
complexes 2a 2e. Make a comprehensive survey of the data
-1e are
1
500 MHz for H; 75 or 125 MHz for 13C) in C6D6 or THF-d8 for
-
rare-earth metal complexes, in DMSO-d6 for the ligands and in
CDCl3 for polyisoprene. Chemical shifts (δ) were reported in
ppm. J values were reported in Hertz. IR spectra were
recorded on a Shimadzu Model FTIR-8400s spectrometer (KBr
plate). HR-MS measurements were conducted with an Agilent
model 6220-TOF mass spectrometer. Gel permeation
chromatography (GPC) analyses of the polymer samples were
carried out at 35 °C using THF as an eluent on a Waters-2414
showed in Table 3 and Table 4, the different substituent
groups on ligands make a different bonding mode between
complexes 1a-1e and 2a-2e, and thus result in differences on
their catalytic activities for isoprene polymerization.
Conclusions
In summary, 2-amidate functionalized indolyl ligands were instrument and calibrated using monodispersed polystyrene
standards at a flow rate of 1.0 mL min-1.
developed for the rare-earth metal chemistry. Reactions of
Preparation of 2-(2,6-iPr2C6H3NHC=O)C8H5NH (H2L1). 1H-
these functionalized indolyl ligands with RE(CH2SiMe3)3(THF)2
produced the new dinuclear organo-rare-earth metal alkyl
indole-2-carboxylic acid (8.06 g, 50.0 mmol) was dissolved in
complexes with different coordination modes depending on
thionyl chloride (20.0 mL), and reacted for 4 h at 40 °C, then
the substituents. Study of the reactivities of the dinuclear
the excess thionyl chloride was evaported under reduced
pressure to give the yellow powder product 1H-indole-2-
carbonyl chloride. Then 50.0 mL dry THF was added to flask to
dissolve the yellow powder, and dry K2CO3 (8.29 g, 60.0 mmol)
as acid binding agent was added to give a yellow turbid
mixture. The mixture was cooled with an ice-water bath with
stirring. To the mixture was added a THF (20.0 mL) solution of
2,6-diisopropylaniline (9.75 g, 55.0 mmol) slowly. The mixture
organo-rare-earth metal alkyl complexes with small organic
molecules such as N,N'-diisopropylcarbodiimide (DIC),
phenylisocyanate,
N-methylallylamine,
phenylacetylene,
pyridine, N-phenylimidazole or 4-dimethylaminopyridine
(DMAP) resulted in findings of the reactivity differences from
those of reported rare-earth metal alkyl complexes, indicating
that ligands steric effects on the reactivities of the complexes.
Study of the catalytic activity of these complexes indicated
that these dinuclear organo-rare-earth metal alkyl complexes
are good pre-catalysts for the isoprene polymerization upon
activation with aluminum alkyls and borate producing
polymers with an excellent regioselectivity (1,4-selectivity up
to 96.1%) at room temperature. It is also found that
substituents on the amidate group of the ligands in the
complexes not only have influence on the coordination of
ligands and reactivity of the complexes, but also have
influence on their catalytic activity towards polymerization of
isoprene in the presence of co-catalysts. This work implies that
was stirred at 0 C for 2 h. The solvent was evaported under
reduced pressure, the residue was washed with ethyl acetate
to give the product as a yellow solid (14.42 g, 90% yield based
1
on 1H-indole-2-carboxylic acid). M. p.: 342
MHz, DMSO-d6, 25

C. H NMR (500

C): δ 11.73 (s, 1H, -NH-), 9.78 (s, 1H, -
CONH-), 7.66 (d, J = 7.64 Hz, 1H, indole-Ar-H), 7.44 (d, J = 8.00
Hz, 1H, indole-Ar-H), 7.38 (s, 1H, indole-Ar-H), 7.32 (t, J = 7.50
Hz, 1H, indole-Ar-H), 7.22 (d, J = 7.50 Hz, 2H, Ar-H), 7.20 (s, 1H,
indole-Ar-H), 7.07 (t, J = 7.50 Hz, 1H, Ar-H), 3.14 (m, 2H,
CH(CH3)2), 1.15 (m, 12H, CH3). 13C NMR (125 MHz, DMSO-d6,
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 7
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Page 8 of 12
ARTICLE
25 C): δ 161.0 (-CONH-), 146.4 (indole-Ar-2-C), 136.7 (indole- Preparation
Journal Name
{[η1:(μ2 Vηie1wηA1r)ti-c2le-O(2n,li6ne-

of
- :
i
Ar-3-C), 132.2, 131.4, 127.8, 127.2, 123.6, 123.0, 121.6, 120.0, Pr2C6H3NCO)Ind]Y(CH2SiMe3)(THF)2}2 (1cD)O. AI: 1m0.e10t3h9o/dC9sDimT0i0la5r07toB
112.4, 103.2, 28.2 (CH(Me)2), 23.5 (CH3). HRMS (APCI) m/z that for the preparation of complex 1a was used by treatment
calcd. for C21H25N2O (M + H+): 321.1961. Found: 321.1960. IR of a toluene (15.0 mL) solution of [Y(CH2SiMe3)3(THF)2] (0.49 g,
(KBr plate, cm-1): ν 3568 (w), 2964 (s), 2870 (m), 1643 (s), 1541 1.0 mmol) and H2L1 (0.32 g, 1.0 mmol) at 0
C. Faint yellow
(s), 1498 (s), 1413 (s), 1384 (m), 1336 (m), 1307 (s),1240 (s), crystals were obtained (600 mg, 47% yield based on the H2L1).
M. p. (sealed): 180 
C (dec.) under Ar. 1H NMR (500 MHz, C6D6,
1182 (m), 821 (m), 806 (m), 767 (m), 746 (s), 648 (m).
Preparation of 2-(2-tBuC6H4NHC=O)C8H5NH (H2L2). A method
similar to that for the preparation of compound H2L1 was used,
with 2-tert-Butylaniline (8.21 g, 55.0 mmol) to replace 2,6-
diisopropylaniline to give the product as a yellow solid (13.16 g,
25 C, TMS): δ 7.61 (d, J = 10.00 Hz, 1H, Ar-H), 7.56 (d, J = 5.00
Hz, 1H, Ar-H), 7.37-7.31 (m, 4H, indole-Ar-H), 7.06-7.03 (m, 1H,
Ar-H), 6.18 (s, 1H, indole-Ar-H), 3.85 (s, 8H, THF), 3.67 (s, 2H, -
CHMe2), 1.36 (s, 8H, THF), 1.31 (d, J = 5.00 Hz, 6H, -CH(CH3)2),
1.22 (d, J = 5.00 Hz, 6H, -CH(CH3)2), -0.04 (s, 9H, -Si(CH3)3), -
90% yield based on 1H-indole-2-carboxylic acid). M. p.: 251
C.
0.34 (s, 2H, Y-CH2-). 13C NMR (125 MHz, C6D6, 25
C, TMS): δ
1H NMR (500 MHz, DMSO-d6, 25

C): δ 11.70 (s, 1H, -NH-), 9.77
165.6 (-O-C=N-), 144.3, 144.1, 140.4, 138.4, 131.3, 124.6, 124.3,
122.6, 122.1, 118.7, 115.7, 108.0, 70.6 (-O-(CH2)2-, THF), 28.1 (-
CHMe2), 25.4 (-(CH2)2-, THF), 25.1 (d, JY-C = 50 Hz, Y-CH2-), 3.9 (-
CH(CH3)2), 1.4 (-SiCMe3). IR (KBr plate, cm-1): v 3047 (w), 2962
(m), 2870 (w), 1645 (s), 1543 (s), 1498 (m), 1413 (m), 1307 (m),
1259 (m), 1242 (m), 1097 (m), 862 (m), 821 (m), 806 (m), 746
(s), 650 (m). Anal. Calcd for C66H98N4O6Si2Y2: C, 62.05; H, 7.73;
N, 4.39. Found: C, 62.33; H, 7.58; N, 4.27.
(s, 1H, -CONH-), 7.67 (d, J = 8.00 Hz, 1H, indole-Ar-H), 7.48-7.44
(m, 2H, Ar-H), 7.33 (s, 1H, indole-Ar-H), 7.31-7.28 (m, 2H, Ar-H),
7.22-7.17 (m, 2H, Ar-H), 7.06 (t, J = 7.50 Hz, 1H, Ar-H), 1.36 (s,
9H, -C(CH3)3). 13C NMR (125 MHz, DMSO-d6, 25
C): δ 160.9 (-
CONH-), 147.3 (indole-Ar-2-C), 136.6 (indole-Ar-3-C), 135.6,
132.0, 131.8, 127.3, 127.2, 126.9, 126.5, 123.5, 121.6, 119.9,
112.4, 103.4, 35.0 (-CMe3), 30.9 (-C(CH3)3). HRMS (APCI) m/z
calcd. for C19H21N2O (M + H+): 293.1648. Found: 293.1642. IR
(KBr plate, cm-1): ν 3569 (w), 3049 (m), 3005 (m), 2907 (m), Preparation
of
{[η1:(μ2 η1 η1)-2-(2,6-
- :
2866 (m), 1647 (w), 1624 (w), 1541 (w), 1498 (w), 1443 (m), iPr2C6H3NCO)Ind]Er(CH2SiMe3)(THF)2}2 (1d). A method similar
1412 (w), 1362 (w), 1339 (w), 1308 (w), 1250 (w), 1086 (s), to that for the preparation of complex 1a was used by
1051 (s), 986 (s), 907 (s), 820 (m), 764 (w), 746 (w), 739 (w), treatment of
700 (s), 650 (s), 573 (s), 534 (s), 478 (m), 430 (s).
a
toluene (15.0 mL) solution of
[Er(CH2SiMe3)3(THF)2] (0.57 g, 1.0 mmol) and H2L1 (0.32 g, 1.0
Preparation
of
{[η1:(μ2 η1 η1)-2-(2,6-
- :
mmol) at 0
C. Pink crystals were obtained (731 mg, 51% yield
1
based on the H2L1). M. p. (sealed): 187

C (dec.) under Ar. H
iPr2C6H3NCO)Ind]Gd(CH2SiMe3)(THF)2}2 (1a). A toluene (15.0
NMR spectra of the complex were not obtained due to the lack
of locking signals for the paramagnetism of the complex. IR
(KBr plate, cm-1): v 3047 (m), 2962 (s), 2868 (m), 1643 (s), 1541
(s), 1500 (s), 1413 (s), 1384 (m), 1363 (m), 1338 (m), 1307 (m),
1257 (m), 1242 (m), 1180 (m), 1056 (m), 1008 (w), 862 (m),
821 (m), 806 (m), 746 (s), 646 (m). Anal. Calcd for
C66H98N4O6Si2Er2: C, 55.27; H, 6.89; N, 3.91. Found: C, 55.65; H,
7.16; N, 4.10.
mL) solution of [Gd(CH2SiMe3)3(THF)2] (0.56 g, 1.0 mmol) and
H2L1 (0.32 g, 1.0 mmol) was stirred at 0
C for about 0.5 h to
give a clear solution. Faint yellow crystals were obtained next
day upon standing the reaction mixture at room temperature
(750 mg, 53% yield based on the H2L1). M. p. (sealed): 173
C
(dec.) under Ar. 1H NMR spectra of the complex were not
obtained due to the lack of locking signals for the
paramagnetism of the complex. IR (KBr plate, cm-1): v 3047 (m),
2962 (s), 2870 (m), 1643 (s), 1541 (s), 1500 (s), 1413 (m), 1384 Preparation
of
{[η1:(μ2 η1 η1)-2-(2,6-
- :
(m), 1363 (m), 1340 (m), 1307 (s), 1244 (m), 1182 (m), 1056 iPr2C6H3NCO)Ind]Yb(CH2SiMe3)(THF)2}2 (1e). A method similar
(m), 862 (m), 806 (m), 746 (m), 646 (m). Anal. Calcd for to that for the preparation of complex 1a was used by
C66H98N4O6Si2Gd2: C, 56.05; H, 6.98; N, 3.96. Found: C, 56.07; H, treatment of
7.23; N, 4.15.
a
toluene (15.0 mL) solution of
[Yb(CH2SiMe3)3(THF)2] (0.58 g, 1.0 mmol) and H2L1 (0.32 g, 1.0
mmol) at 0

C. Deep red crystals were obtained (723 mg, 50%
C (dec.) under Ar.
Preparation
of
{[η1:(μ2 η1 η1)-2-(2,6-
- :
yield based on the H2L1). M. p. (sealed): 195

iPr2C6H3NCO)Ind]Dy(CH2SiMe3)(THF)2}2 (1b). A method similar
to that for the preparation of complex 1a was used by
1H NMR spectra of the complex were not obtained due to the
lack of locking signals for the paramagnetism of the complex.
IR (KBr plate, cm-1): v 3049 (w), 2962 (s), 2870 (w), 1643 (s),
1541 (s), 1502 (m), 1413 (s), 1363 (m), 1344 (m), 1307 (s), 1246
(s), 1182 (m), 1056 (s), 862 (s), 800 (m), 746 (s), 648 (m). Anal.
Calcd for C66H98N4O6Si2Yb2: C, 54.83; H, 6.83; N, 3.88. Found: C,
54.75; H, 7.14; N, 3.64.
treatment of
a
toluene (15.0 mL) solution of
[Dy(CH2SiMe3)3(THF)2] (0.57 g, 1.0 mmol) and H2L1 (0.32 g, 1.0
mmol) at 0 C. Faint yellow crystals were obtained (670 mg,
47% yield based on the H2L1). M. p. (sealed): 176

C (dec.)
1
under Ar. H NMR spectra of the complex were not obtained
due to the lack of locking signals for the paramagnetism of the
complex. IR (KBr plate, cm-1): v 3047 (m), 2964 (s), 2870 (m), Preparation
of
:
η1):η1-2-(2,6-iPr2C6H3NCO)Ind]Y(THF)}2 (1ca). A THF (15.0
{[η1 η1-2-(2,6-iPr2C6H3NHC=O)Ind-η1:(μ2
: -
1643 (s), 1541 (s), 1500 (s), 1413 (s), 1363 (m), 1307 (s), 1259 η1
(m), 1240 (m), 1182 (m), 1058 (m), 821 (m), 806 (m), 746 (m), mL) solution of [Y(CH2SiMe3)3(THF)2] (0.49 g, 1.0 mmol) and
648 (m). Anal. Calcd for C66H98N4O6Si2Dy2: C, 55.64; H, 6.93; N, H2L1 (0.64 g, 2.0 mmol) was stirred at room temperature for 3
3.93. Found: C, 55.65; H, 7.13; N, 3.64.
h. The solvent was evaporated under reduced pressure. The
residue was extracted with 10 mL n-hexane and 5 mL toluene.
8 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
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Journal Name
ARTICLE
View Article OnliCne,
Faint yellow crystals were obtained at room temperature for J = 10.00 Hz, 6H, -CH(CH3)2). 13C NMR (125 MHz, THF-d8, 25

several days. [799 mg, 50% yield based on the rare-earth metal TMS): δ 166.1 (-O-C=N-), 145.5, 144.4,DO14I:010.9.1,03194/C0.93D,T0103590.70B,
complex Y(CH2TMS)3(THF)2]. M. p. (sealed): 187 C (dec.) under 131.4, 124.1, 123.8, 121.7, 117.7, 115.9, 114.7, 112.6, 107.3,

Ar. 1H NMR spectra of the complex were not obtained, due to 68.0 (-O-(CH2)2-, THF), 59.6 (-CH=CH2), 55.4 (-CH=CH2), 38.7 (N-
the poor solubility of the complex. IR (KBr plate, cm-1): v 3240 CH2-), 36.4 (-CMe2), 32.5 (CH(CH3)2), 28.5 (-(CH2)2-, THF), 1.2
(m), 3061 (m), 2963 (m), 2928 (m), 2868 (m), 1645 (m), 1539 (N-CH3). IR (KBr plate, cm-1): v 2963 (m), 2868 (m), 1645 (m),
(m), 1504 (m), 1487 (m), 1472 (m), 1418 (m), 1362 (m), 1341 1539 (w), 1504 (m), 1416 (m), 1362 (m), 1344 (m), 1310 (m),
(m), 1310 (m), 1258 (s), 1246 (s), 1231 (s), 1180 (s), 1148 (s), 1258 (m), 1240 (m), 1182 (s), 1144 (s), 1121 (s), 1057 (s), 1007
1121 (s), 1098 (s), 1057 (s), 1009 (s), 986 (s), 935 (s), 899 (s), (s), 986 (s), 912 (s), 800 (s), 768 (s), 746 (m), 644 (s), 621 (s),
812 (s), 800 (s), 770 (s), 748 (m), 573 (s), 527 (s), 482 (s), 432 569 (s). Anal. Calcd for C66H92N6O6Y2: C, 63.76; H, 7.46; N, 6.76.
Found: C, 63.62; H, 6.96; N, 6.49.
Preparation of
iPr2C6H3NCO)Ind]Yb(C≡CPh)(THF)2}2 (1ea). A THF (15.0 mL)
(N,N
)(iPrN)2C(CH2SiMe3)](THF)}2 (1cb). A toluene (15.0 mL) solution of complex 1e (0.69 g, 0.50 mmol) and
(s). Anal. Calcd for C92H106N8O6Y2·3C7H8: C, 72.54; H, 6.84; N,
{[η1:(μ2 η1 η1)-2-(2,6-
- :
5.99. Found: C, 72.38; H, 7.00; N, 5.90.
- : -
Preparation of {[η1:(μ2 η1 η1)-2-(2,6-iPr2C6H3NCO)Ind]Y[κ2
solution of complex 1c (0.64 g, 0.50 mmol) and DIC (157 μL, phenylacetylene (110 μL, 1.00 mmol) was stirred at 60 °C for
1.00 mmol) was stirred at room temperature for 4 h. The 12 h. The solvent was evaporated under reduced pressure. The
solvent was evaporated under reduced pressure. The residue residue was extracted with 10 mL n-hexane and 5 mL THF.
was extracted with 10 mL THF and 6 mL n-hexane. Colorless Yellow crystals were obtained upon standing the solution at 0
crystals were obtained upon standing the solution at -30 °C for
several days (229 mg, 30% yield based on the complex 1c). M. 1e). M. p. (sealed): 107
p. (sealed): 138
C (dec.) under Ar. 1H NMR (500 MHz, THF-d8, the complex were not obtained, due to the lack of locking
25 C, TMS): δ 7.42 (d, J = 10.00 Hz, 1H, indole-Ar-H), 7.21 (s, signals for the paramagnetism of the complex. IR (KBr plate,
C for several days (258 mg, 35% yield based on the complex
1

C (dec.) under Ar. H NMR spectra of


1H, indole-Ar-H), 6.91 (d, J = 5.00 Hz, 2H, indole-Ar-H), 6.58 (t, J cm-1): v 1773 (s), 1751 (s), 1734 (s), 1719 (s), 1701 (s), 1684 (s),
= 10.00 Hz, 2H, Ar-H), 6.39 (t, J = 10.00 Hz, 1H, Ar-H), 6.16 (d, J 1638 (m), 1618 (m), 1558 (s), 1541 (s), 1533 (s), 1508 (s), 1499
= 10.00 Hz, 1H, indole-Ar-H), 3.54 (t, J = 10.00 Hz, 4H, THF), (s), 1491 (s), 1474 (s), 1458 (s), 1437 (s), 1400 (s), 1385 (s),
1.71-1.69 (m, 4H, THF), 1.55 (s, 2H, -CH2SiMe3), 0.94 (d, J = 1364 (s), 1341 (s), 1308 (s), 1261 (s), 1094 (s), 1022 (s), 802 (s),
5.00 Hz, 24H, -CH(CH3)2), 0.8-0.83 (m, 4H, -CHMe2), 0.04 (s, 9H, 746 (s), 619 (s). Anal. Calcd for C74H86N4O6Yb2: C, 60.31; H, 5.88;
N, 3.80. Found: C, 59.93; H, 5.62; N, 3.72.
-Si(CH3)3). 13C NMR (125 MHz, THF-d8, 25
C, TMS): δ 171.4 (-O-
{[η1:(μ2 η1)-2-(2,6-
- :
η1
C=N-), 153.4, 148.4, 147.5, 140.6, 131.9, 131.4, 128.4, 123.6,
123.4, 122.1, 120.9, 119.3, 118.4, 103.0, 68.0 (-O-(CH2)2-, THF)
32.3 (Ar-CHMe2), 29.3 (Ar-CH(CH3)2), 23.3 (-(CH2)2-, THF), 20.3
(N-CHMe2), 15.0 (N-CH(CH3)2), 14.2 (N-C-N), 1.2 (-SiCMe3). IR
(KBr plate, cm-1): v 3048 (w), 2965 (w), 2870 (m), 1643 (w),
1541 (w), 1503 (w), 1487 (m), 1414 (m), 1385 (m), 1366 (m),
1339 (m), 1308 (m), 1242 (m), 1182 (s), 1128 (s), 1061 (s), 1011
(s), 982 (s), 937 (s), 901 (s), 833 (m), 824 (m), 806 (s), 768 (s),
746 (w), 648 (s), 569 (s), 529 (s), 486 (s), 428 (s), 419 (s), 399 (s).
Anal. Calcd for C72H110N8O4Si2Y2: C, 62.41; H, 8.00; N, 8.09.
Found: C, 62.57; H, 8.22; N, 7.91.
Preparation
of
iPr2C6H3NCO)Ind]Yb(CH2SiMe3)(Pyridine)(THF)}2
(1eb).
A
toluene (15.0 mL) solution of complex 1e (0.69 g, 0.50 mmol)
and Pyridine (56 μL, 1.00 mmol) was stirred at room
temperature for 3 h. The solvent was evaporated under
reduced pressure. The residue was extracted with 10 mL
toluene and 5 mL n-hexane. Pale brown crystals were obtained
standing the solution at 0

C for several days (226 mg, 31%
C (dec.)
yield based on the complex 1e). M. p. (sealed): 127

1
under Ar. H NMR spectra of the complex were not obtained
due to lack of locking signals for the paramagnetism of the
Preparation
of
{[η1:(μ2 η1 η1)-2-(2,6- complex. IR (KBr plate, cm-1): v 2963 (m), 1641 (m), 1541 (m),
- :
iPr2C6H3NCO)Ind]Y[N(Me)CH2CH=CH2](THF)2}2 (1cc). A toluene 1508 (m), 1439 (m), 1414 (m), 1385 (m), 1346 (m), 1310 (m),
(15.0 mL) solution of complex 1c (0.64 g, 0.50 mmol) and N- 1248 (m), 1183 (s), 1148 (s), 1123 (s), 1059 (s), 1032 (s), 1007
Methylallylamine (96 μL, 1.00 mmol) was stirred at room (s), 935 (s), 860 (m), 799 (s), 746 (m), 702 (m), 650 (s), 617 (s),
temperature for 4 h. The solvent was evaporated under 571 (s). Anal. Calcd for C68H92N6O4Si2Yb2·0.5C7H8: C, 57.03; H,
6.43; N, 5.58. Found: C, 57.18; H, 6.16; N, 5.68.
Preparation of
{[η1:(μ2
reduced pressure. The residue was extracted with 10 mL THF
and 9 mL n-hexane. Faint yellow crystals were obtained upon
- :
η1 η1)-2-(2,6-
iPr2C6H3NCO)Ind]Yb(CH2SiMe3)(η1-(N)-C3H3N2C6H5)(THF)}2
(1ec). A toluene (15.0 mL) solution of complex 1e (0.69 g, 0.50
mmol) and N-Phenylimidazole (126 μL, 1.00 mmol) was stirred
at room temperature for 3 h. The solvent was evaporated
under reduced pressure. The residue was extracted with 10 mL
toluene and 5 mL n-hexane. Red crystals were obtained upon
standing the solution at 0
yield based on the complex 1c). M. p. (sealed): 167
under Ar. 1H NMR (500 MHz, THF-d8, 25
C, TMS): δ 7.31 (d, J =

C for several days (249 mg, 40%

C (dec.)

5.00 Hz, 1H, Ar-H), 7.12 (s, 1H, Ar-H), 7.10 (d, J = 5.00 Hz, 1H,
Ar-H), 7.08 (s, 1H, Ar-H), 7.03 (d, J = 5.00 Hz, 1H, Ar-H), 6.81 (t,
J = 7.50 Hz, 1H, Ar-H), 6.57 (t, J = 7.50 Hz, 1H, Ar-H), 5.47 (s, 1H,
indole-Ar-H), 4.93-4.89 (m, 2H, -CH=CH2), 4.35-4.33 (m, 1H, -
CH=CH2), 3.51(t, J = 5.00 Hz, 8H, THF), 3.44-3.33 (m, 2H, -
CHMe2), 3.09-3.00 (m, 2H, -NCH2-), 2.58 (s, 3H, -NCH3), 1.68-
1.65 (m, 8H, THF), 1.06 (d, J = 10.00 Hz, 6H, -CH(CH3)2), 0.85 (d,
standing the solution at 0

C for several days (238 mg, 30%
C (dec.)
yield based on the complex 1e). M. p. (sealed): 151

1
under Ar. H NMR spectra of the complex were not obtained
due to the lack of locking signals for the paramagnetism of the
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 9
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ARTICLE
Journal Name
complex. IR (KBr plate, cm-1): v 2961 (w), 2866 (m), 1641 (w), yield based the rare-earth metal complex Yb(CH2TMS)3(THF)2].
View Article Online
DOI: 10.1039/C9DT00507B
C (dec.) under Ar. H NMR spectra of the
1
1601 (w), 1541 (w), 1512 (w), 1416 (m), 1346 (m), 1308 (w), M. p. (sealed): 210

1246 (m), 1180 (s), 1144 (s), 1119 (m), 1059 (m), 1007 (s), 988 complex were not obtained due to the lack of locking signals
(s), 964 (s), 928 (s), 912 (s), 860 (m),748 (w), 692 (m), 658 (m), for the paramagnetism of the complex. IR (KBr plate, cm-1): v
523 (s). Anal. Calcd for C76H98N8O4Si2Yb2: C, 57.41; H, 6.21; N, 1643 (m), 1541 (m), 1501 (s), 1414 (s), 1385 (s), 1364 (s), 1339
7.05. Found: C, 57.42; H, 5.88; N, 7.00.
(s), 1308 (s), 1260 (s), 1240 (s), 1182 (s), 1082 (s), 920 (s), 822
(s), 806 (s), 768 (s), 746 (s), 739 (s). Anal. Calcd for
C79H90N14O3Yb2·THF: C, 58.58; H, 5.80; N, 11.52. Found: C,
58.34; H, 5.82; N, 11.42.
Preparation
of
{[η1:(μ2 η1 η1)-2-(2,6-
- :
iPr2C6H3NCO)Ind]Yb(CH2SiMe3)(DMAP)2}2 (1ed). Complex 1ed
could be synthesized by the following two methods: path A, a
THF (10.0 mL) solution of complex 1e (0.69 g, 0.50 mmol) and Preparation
of
:
η1-2-(2,6-iPr2C6H3NCO)Ind]Yb2[η1-(N)-
{[η1:(μ2 η1 η1):η1-2-(2,6-
- :
DMAP (0.24 g, 2.0 mmol) was stirred at room temperature for iPr2C6H3NCO)Ind]2[η1
1 min and stand overnight, then filtration.
C3H3N2CH2C6H5]4} (1ef). A toluene (15.0 mL) solution of
Yb(CH2SiMe3)3(THF)2 (0.58 g, 1.0 mmol) and N-Benzylimidazole
(0.31 g, 2.0 mmol) was stirred at room temperature for 2 h,
then to the solution was added H2L1 (0.32 g, 1.0 mmol). The
reaction mixture was stirred at room temperature for 3 h, The
solvent was evaporated under reduced pressure. The residue
was extracted with 10 mL THF and 2 mL n-hexane. Yellow
Alternate path toluene (15.0 mL) solution of
B
, a
Yb(CH2SiMe3)3(THF)2 (0.58 g, 1.0 mmol) and DMAP (0.24 g, 2.0
mmol) was stirred at room temperature for 0.5 h, to the
solution was added H2L1 (0.32 g, 1.0 mmol), and the mixture
was stirred at room temperature for 3 h, The solvent was
evaporated under reduced pressure. The residue was
extracted with 10 mL THF and 5 mL n-hexane. Red crystals
crystals were obtained upon standing the solution at 0
several days [773 mg, 40% yield based the rare-earth metal
complex Yb(CH2TMS)3(THF)2]. M. p. (sealed): 113 C (dec.)
C for
were obtained upon standing the solution at 0
days (823 mg, 50% yield based on the complex 1e). M. p.
(sealed): 112
C (dec.) under Ar. 1H NMR spectra of the
C for several

1
under Ar. H NMR spectra of the complex were not obtained
due to the lack of locking signals for the paramagnetism of the
complex. IR (KBr plate, cm-1): v 1773 (s), 1751 (s), 1734 (s),
1719 (s), 1701 (s), 1684 (s), 1618 (m), 1578 (s), 1570 (s), 1558
(s), 1533 (s), 1508 (s), 1499 (s), 1458 (s), 1406 (s), 1385 (s),
1364 (s), 1308 (s), 1261 (s), 1231 (s), 1078 (s), 1030 (s), 802 (s),
746 (s), 737 (s), 710 (s), 662 (s), 627 (s), 617 (s). Anal. Calcd for
C103H106N14O3Yb2·4C7H8: C, 68.33; H, 6.04; N, 8.52. Found: C,
68.01; H, 6.40; N, 8.81.

complex were not obtained due to the lack of locking signals
for the paramagnetism of the complex. IR (KBr plate, cm-1): v
1641 (m), 1609 (m), 1539 (m), 1506 (m), 1489 (s), 1447 (m),
1418 (m), 1383 (m), 1310 (s), 1260 (s), 1227 (m), 1182 (s), 1123
(s), 1105 (s), 1065 (s), 993 (m), 806 (m), 746 (s), 739 (s), 532
(m). Anal. Calcd for C78H106N12O2Si2Yb2·2THF: C, 57.70; H, 6.87;
N, 9.39. Found: C, 58.09; H, 7.08; N, 9.02.
Preparation of Yb(CH2SiMe3)3(DMAP)2 (3a). A toluene (15.0
mL) solution of Yb(CH2SiMe3)3(THF)2 (0.58 g, 1.0 mmol) and
DMAP (0.24 g, 2.0 mmol) was stirred at room temperature for
0.5 h. The solvent was evaporated under reduced pressure.
The residue was extracted with 10 mL n-hexane and 5 mL
toluene. Yellow crystals were obtained upon standing the
Preparation
of
{[η1:(μ2 η1 η1):η1-2-(2-
- :
tBuC6H4NCO)Ind]Gd(CH2SiMe3)(THF)2}2 (2a). A toluene (15.0
mL) solution of [Gd(CH2SiMe3)3(THF)2] (0.56 g, 1.0 mmol) and
H2L2 (0.29 g, 1.0 mmol) was stirred at room temperature for
about several seconds to give a clear solution. Faint yellow
crystals were obtained the next day upon standing the
reaction solution overnight (762 mg, 55% yield based on the
solution at -30
the rare-earth metal complex Yb(CH2TMS)3(THF)2]. M. p.
(sealed): 100
C (dec.) under Ar. 1H NMR spectra of the
C for several days. [475 mg, 70% yield based
H2L2). M. p. (sealed): 70 C (dec.) under Ar. 1H NMR spectra of


the complex were not obtained due to the lack of locking
signals for the paramagnetism of the complex. IR (KBr plate,
cm-1): v 2955 (s), 1645 (m), 1626 (m), 1543 (m), 1508 (s), 1443
(s), 1414 (s), 1364 (s), 1341 (s), 1312 (s), 1263 (s), 1250 (s),
1196 (s), 1086 (s), 1051 (s), 984 (s), 853 (s), 829 (s), 762 (s), 746
(s). Anal. Calcd for C62H90N4O6Si2Gd2·2C7H8: C, 59.18; H, 6.93; N,
3.63. Found: C, 59.14; H, 6.96; N, 3.72.
complex were not obtained due to the lack of locking signals
for the paramagnetism of the complex. IR (KBr plate, cm-1): v
1604 (w), 1537 (m), 1522 (m), 1447 (m), 1379 (m), 1225 (m),
1103 (s), 1069 (s), 989 (m), 945 (s), 808 (m), 750 (m), 540 (m),
530 (m). Anal. Calcd for C26H53N4Si3Yb: C, 45.99; H, 7.87; N,
8.25. Found: C, 45.08; H, 7.61; N, 8.61.
Preparation
of
η1-2-(2,6-iPr2C6H3NCO)Ind]Yb2[η1-(N)-
toluene (15.0 mL) solution of
{[η1:(μ2 η1 η1):η1-2-(2,6-
- :
{[η1:(μ2 η1 η1):η1-2-(2-
- :
iPr2C6H3NCO)Ind]2[η1
:
Preparation
of
tBuC6H4NCO)Ind]Dy(CH2SiMe3)(THF)2}2 (2b). A method similar
to that for the preparation of complex 2a was used by
C3H3N2CH3]4} (1ee).
A
Yb(CH2SiMe3)3(THF)2 (0.58 g, 1.0 mmol) and N-
Methylimidazole (159 μL, 2.0 mmol) was stirred at room
temperature for 2 h, then to the reaction mixture was added
H2L1 (0.32 g, 1.0 mmol). The reaction mixture was then stirred
at room temperature for 3 h, The solvent was evaporated
under reduced pressure. The residue was extracted with 10 mL
THF and 2 mL n-hexane. Yellow crystals were obtained upon
treatment of
a
toluene (15.0 mL) solution of
[Dy(CH2SiMe3)3(THF)2] (0.57 g, 1.0 mmol) and H2L2 (0.29 g, 1.0
mmol) at room temperature. Faint yellow crystals were
obtained the next day upon standing the solution at room
temperature (657 mg, 48% yield based on the H2L2). M. p.
(sealed): 101 
C (dec.) under Ar. 1H NMR spectra of the
complex were not obtained due to the lack of locking signals
standing the solution at 0 C for several days [733 mg, 45%
for the paramagnetism of the complex. IR (KBr plate, cm-1): v
10 | J. Name., 2012, 00, 1-3
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ARTICLE
2955 (s), 1645 (w), 1626 (m), 1545 (m), 1508 (m), 1443 (s), solution of [Yb(CH2SiMe3)3(THF)2] (0.58 g, 1.0 mmol) and H2L2
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1414 (s), 1364 (s), 1341 (s), 1312 (m), 1265 (s), 1250 (s), 1196 (0.58 g, 2.0 mmol) was stirred at roomDtOeIm: 1p0e.10ra3t9u/Cre9DfTo0r05307hB.
(s), 1148 (s), 1117 (s), 1086 (s), 1051 (s), 984 (s), 862 (s), 830 (s), The solvent was evaporated under reduced pressure. The
762 (s), 746 (s). Anal. Calcd for C62H90N4O6Si2Dy2: C, 54.41; H, residue was extracted with 10 mL toluene and 5 mL n-hexane.
6.63; N, 4.09. Found: C, 54.20; H, 6.74; N, 4.35.
Red crystals were obtained upon standing the solution at room
temperature for several days (546 mg, 33% yield based on the
Preparation
of
{[η1:(μ2 η1 η1):η1-2-(2-
- :
H2L2). M. p. (sealed): 171 C (dec.) under Ar. 1H NMR spectra of

tBuC6H4NCO)Ind]Y(CH2SiMe3)(THF)2}2 (2c). A method similar to
that for the preparation of complex 2a was used, consisting of
the complex were not obtained due to the lack of locking
signals for paramagnetism. IR (KBr plate, cm-1): v 2957 (m),
1647 (m), 1636 (m), 1618 (m), 1558 (m), 1541 (m), 1533 (m),
1508 (m), 1420 (m), 1312 (m), 1248 (m), 1148 (m), 1119 (m),
1088 (m), 1053(m), 860 (m), 746 (m), 669 (m), 617 (m). Anal.
Calcd for C84H90N8O6Yb2·C7H8: C, 62.60; H, 5.66; N, 6.42. Found:
C, 62.27; H, 6.04; N, 6.24.
the treatment of
a
toluene (15.0 mL) solution of
[Y(CH2SiMe3)3(THF)2] (0.49 g, 1.0 mmol) and H2L2 (0.29 g, 1.0
mmol) at room temperature. Faint yellow crystals were
obtained the next day upon standing the solution at room
temperature (623 mg, 51% yield based on the H2L2). M. p.
(sealed): 65
were not obtained due to the poor solubility of the complex. IR Preparation of {[η1:(μ2
(KBr plate, cm-1): v 2955 (s), 1645 (m), 1626 (m), 1543 (m),
N,O)-OC(CH2SiMe3)NC6H5](THF)}2 (2eb). A toluene (15.0 mL)

C (dec.) under Ar. 1H NMR spectra of the complex
- : -
η1 η1):η1-2-(2-tBuC6H4NCO)Ind]Yb[κ2
(
1508 (m), 1443 (s), 1414 (s), 1364 (s), 1341 (s), 1312 (s), 1263 solution of complex 2e (0.69 g, 0.50 mmol) and
(s), 1250 (s), 1196 (s), 1148 (s), 1117 (s), 1086 (s), 1051 (s), 984 Phenylisocyanate (109 μL, 1.00 mmol) was stirred at room
(s), 953 (s), 829 (s), 762 (s), 746 (s). Anal. Calcd for temperature for 3 h. Red crystals were obtained upon standing
C62H90N4O6Si2Y2: C, 60.97; H, 7.43; N, 4.59. Found: C, 60. 91; H, the solution at room temperature for several days (356 mg,
7.44; N, 4.43.
48% yield based on the complex 2e). M. p. (sealed): 224 C
(dec.) under Ar. 1H NMR spectra of the complex were not
obtained due to the lack of locking signals for the
paramagnetism of the complex. IR (KBr plate, cm-1): v 1647 (m),
1599 (m), 1541 (m), 1533 (m), 1499 (m), 1441 (m), 1420 (m),
1315 (m), 1250 (m), 1198 (s), 1142 (s), 1088 (s), 1053(s), 1007
(s), 988 (s), 849 (m), 748 (m), 692 (s). Anal. Calcd for
C68H84N6O6Si2Yb2·1.5C7H8: C, 58.13; H, 5.97; N, 5.18. Found: C,
57.93; H, 5.93; N, 4.99.
Preparation
of
{[η1:(μ2 η1 η1):η1-2-(2-
- :
tBuC6H4NCO)Ind]Er(CH2SiMe3)(THF)2}2 (2d). A method similar
to that for the preparation of complex 2a was used, consisting
of the treatment of
a toluene (15.0 mL) solution of
[Er(CH2SiMe3)3(THF)2] (0.57 g, 1.0 mmol) and H2L2 (0.29 g, 1.0
mmol) at room temperature. Pink crystals were obtained the
next day upon standing the solution at room temperature (758
mg, 55% yield based on the H2L2). M. p. (sealed): 90

C (dec.)
1
under Ar. H NMR spectra of the complex were not obtained
Isoprene Polymerization. The procedures for isoprene
due to the lack of locking signals for the paramagnetism of the polymerization catalyzed by these complexes were similar; a
complex. IR (KBr disk, cm-1): v 2955 (m), 1645 (w), 1626 (m), typical polymerization procedure is described as follow. A 50
1541 (w), 1508 (m), 1443 (s), 1414 (m), 1364 (s), 1341 (s), 1312 mL Schlenk flask, equipped with a magnetic stirring bar, was
(m), 1250 (s), 1196 (s), 1148 (s), 1117 (s), 1088 (s), 1051 (s), charged the desired amount of solvent, the organo-rare-earth
984 (s), 862 (s), 829 (s),762 (s), 746 (s). Anal. Calcd for alkyl complex, borate, alkyl aluminum, and isoprene. The
C62H90N4O6Si2Er2: C, 54.04; H, 6.58; N, 4.07. Found: C, 53.85; H, mixture was stirred vigorously for the desired time, during
6.46; N, 4.10.
which an increase of viscosity was observed. The reaction
mixture was quenched be addition of 30 mL of acidified
methanol. The polymer was coagulated, washed with
methanol two times, and finally dried under vacuum to a
constant weight.
Preparation
of
{[η1:(μ2 η1 η1):η1-2-(2-
- :
tBuC6H4NCO)Ind]Yb(CH2SiMe3)(THF)2}2 (2e). A method similar
to that for the preparation of complex 2a was used, consisting
of the treatment of
a toluene (15.0 mL) solution of
[Yb(CH2SiMe3)3(THF)2] (0.58 g, 1.0 mmol) and H2L2 (0.29 g, 1.0
Crystal Structure Analyses of Complexes. A suitable single-
mmol) at room temperature. Red crystals were obtained the crystal of each complex was mounted in a sealed capillary.
next day upon standing the solution at room temperature (709 Diffraction was performed on a Bruker SMART APEX II CCD
mg, 51% yield based on the H2L2). M. p. (sealed): 76

C (dec.) area detector diffractometer using graphite-monochromated
1
under Ar. H NMR spectra of the complex were not obtained Mo Kα radiation (λ = 0.71073 Å) at 293(2) K, φ and ω scan
due to the lack of locking signals for the paramagnetism of the technique. An empirical absorption correction was applied
complex. IR (KBr plate, cm-1): v 2953 (s), 1645 (w), 1626 (m), using the SADABS program.28 All structures were solved by
1541 (w), 1508 (m), 1443 (s), 1414 (m), 1364 (s), 1341 (s), 1312 direct methods, completed be subsequent difference Fourier
(m), 1250 (s), 1194 (s), 1148 (s),1117 (s), 1086 (s), 1051 (s), 984 syntheses, and refined anisotropically for all non-hydrogen
(s), 862 (s), 829 (s), 802 (s), 762 (s), 746 (m). Anal. Calcd for atoms by full-matrix least-squares calculations based on F2
C62H90N4O6Si2Yb2(-2THF): C, 52.02; H, 5.99; N, 4.50. Found: C, using the SHELXTL program package29 and Olex2 program.30
51.81; H, 6.02; N, 4.16.
Preparation of
η1 η1):η1-2-(2-tBuC6H4NCO)Ind]Yb(THF)}2 (2ea). A THF (15.0 mL)
The hydrogen atom coordinates were calculated with SHELXTL
by using an appropriate riding model with varied thermal
parameters. The residual electron densities were of no
chemical significance. Selected bond lengths and angles are
{[η1 η1-2-(2-tBuC6H4NHC=O)Ind-η1:(μ2
: -
:
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J. Name., 2013, 00, 1-3 | 11
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ARTICLE
Journal Name
Liu, W.-H. Sun, Y. Zeng, D. Wang, W. Zhang, Y. Li,
listed in Table 1, and crystal data and details of the data
collection and structure refinements are given in the ESI. All
crystal structure diagrams were drawn by Ortep-3 program.31
View Article Online
Organometallics, 2010, 29, 2459-2464D. OI: 10.1039/C9DT00507B
10 X.-g. Zhou, L.-b. Zhang, M. Zhu, R.-f. Cai, L.-h. Weng,
Organometallics, 2001, 20, 5700-5706.
11 D.-H. Lee, J. H. Lee, B. K. Park, E. Y. Kim, Y. Kim, C. Kim, I.-M.
Lee, Inorg. Chim. Acta, 2009, 362, 5097-5102.
Conflicts of interest
There are no conflicts to declare.
12 J. Jarusiewicz, Y. Choe, K. S. Yoo, C. P. Park, K. W. Jung, J. Org.
Chem., 2009, 74, 2873-2876.
13 K. S. Yoo, J. O'Neill, S. Sakaguchi, R. Giles, J. H. Lee, K. W. Jung,
J. Org. Chem., 2010, 75, 95-101.
14 Z. Huang, S. Wang, X. Zhu, Q. Yuan, Y. Wei, S. Zhou, X. Mu,
Inorg. Chem. 2018, 57, 15069-15078.
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