Synthesis and characterization of yttrium complexes bearing a bulky arylamido ancillary ligand

Article abstract of DOI:10.1016/j.ica.2007.08.010

Reaction of anhydrous YCl₃ with 1 equiv. of arylamido lithium 2,6-ⁱPr₂C₆H₃NSiⁱPr₃Li in THF gave an anionic mono-arylamido-ligated yttrium dichloride complex {[2,6-ⁱPr₂C₆H₃NSiⁱPr₃]YCl₂(THF)}₂[LiCl(THF)₂] (1). Alkylation of 1 with 4 equiv. of LiCH₂SiMe₃ afforded an anionic arylamido-ligated yttrium tris(alkyl) complex [2,6-ⁱPr₂C₆H₃NSiⁱPr₃]Y(CH₂SiMe₃)₃Li(THF)₂ (2). Both complexes were characterized by NMR, elementary analysis, and X-ray structural determination.

Full text of DOI:10.1016/j.ica.2007.08.010

Available online at www.sciencedirect.com
Inorganica Chimica Acta 361 (2008) 1255–1260
www.elsevier.com/locate/ica
Synthesis and characterization of yttrium complexes bearing a bulky
arylamido ancillary ligand
*
Bo Shen, Liyan Ying, Jue Chen, Yunjie Luo
School of Biological and Chemical Engineering, Ningbo Institute of Technology, Zhejiang University, Ningbo 315100, China
Received 27 April 2007; received in revised form 29 July 2007; accepted 12 August 2007
Available online 23 August 2007
Abstract
Reaction of anhydrous YCl3 with 1 equiv. of arylamido lithium 2,6-iPr2C6H3NSiiPr3Li in THF gave an anionic mono-arylamido-
ligated yttrium dichloride complex {[2,6-iPr2C6H3NSiiPr3]YCl2(THF)}2[LiCl(THF)2] (1). Alkylation of 1 with 4 equiv. of LiCH2SiMe3
afforded an anionic arylamido-ligated yttrium tris(alkyl) complex [2,6-iPr2C6H3NSiiPr3]Y(CH2SiMe3)3Li(THF)2 (2). Both complexes
were characterized by NMR, elementary analysis, and X-ray structural determination.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Arylamido yttrium complex; Synthesis; Crystal structure
1. Introduction
tate ancillary ligand to stabilize not only rare earth metal
bis(alkyl) complexes, but also active cationic rare earth
mono(alkyl) complexes [5]. As part of this extensive
study, we report here the synthesis, crystal structure of
the yttrium complexes bearing a much bulkier arylamido
ligand, {[2,6-iPr2C6H3NSiiPr3]YCl2(THF)}2[LiCl(THF)2]
(1) and [2,6-iPr2C6H3NSiiPr3]Y(CH2SiMe3)3Li(THF)2 (2).
Organo rare earth metallocene complexes have been
scrutinized intensively during the past two decades because
these species can act as catalysts for organic transformation
reactions and olefin polymerizations [1]. In an attempt to
extend the possibility for modifying and controlling the
reactivity of rare earth metal complexes, currently, alterna-
tive ligand setting other than cyclopentadienyl anions are
also experiencing considerable attention to create different
steric and electronic environments at the reactive site of
rare earth metals [2]. Among those non-cyclopentadienyl
spectator ligands, arylamide is one of the ideal candidates,
for their steric and electronic environment can be tuned
easily by the variation of substituents on both the phenyl
ring and nitrogen atom. Although such ligands are able
to create well-defined reaction metal centers in organome-
tallic chemistry [3,4], we are aware the examples of
mono-arylamido-ligated rare earth metal complexes
remain quite limited [5]. Recently, we reported that arylam-
ido anion [2,6-iPr2C6H3NSiMe3]ꢀ can serve as monoden-
2. Results and discussion
2.1. Synthesis and characterization of {[2,6-iPr2C6H3NSii-
Pr3]YCl2 (THF)}2[LiCl(THF)2] (1) and [2,6-iPr2C6H3-
NSiiPr3] Y(CH2SiMe3)2Li(CH2SiMe3)(THF)2 (2)
Previously, we reported that arylamido anion
[2,6-iPr2C6H3NSiMe3]ꢀ could serve as monodentate ligand
to support rare earth metal bis(alkyl) complexes [2,6-iPr2-
C6H3NSiMe3]Ln(CH2 SiMe3)2(THF) (Ln = Sc, Y, Ho–
Lu), which could be obtained from the alkane elimination
reaction of the rare earth metal tris(alkyl) com-
plexes Ln(CH2SiMe3)3(THF)2 with 1 equiv. amount of
2,6-iPr2C6H3NHSiMe3 in a straightforward manner [5].
Unexpectedly, when a sterically much bulkier arylamine
*
Corresponding author.
E-mail address: lyj@nit.zju.edu.cn (Y. Luo).
0020-1693/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2007.08.010

1256
B. Shen et al. / Inorganica Chimica Acta 361 (2008) 1255–1260
i
Li
Si Pr
i
NH2
NHSi Pr
N
1)
n-BuLi
n
-BuLi
i
2) Si Pr Cl
3
Scheme 1.
1
2,6-iPr2C6H3NHSiiPr3 was employed in the same synthetic
strategy to prepare mono-arylamido-ligated rare earth
metal bis(alkyl) complexes, no aimed product was observed
from NMR monitoring experiments. Therefore, we turned
our attention to prepare rare earth metal alkyl complexes
by means of salt metathesis reaction.
not observed in solution as shown by NMR spectra. H
NMR and 13C NMR spectra of 1 in THF-d8 showed one
set of signal for Si[(CH3)2CH]3, two sets of signals for the
isopropyl groups on the phenyl ring, suggesting that rota-
tion of phenyl ring around the N–Cipso bond is highly
restricted. Similarly, NMR spectra of 2 in C6D6 indicated
the rotation of phenyl ring of the arylamido ligand is also
strictly prohibited. In 2, although there were two terminal
trimethylsilylmethyl groups and one bridged trim-
ethylsilylmethyl group, only one set of resonance for the
methylene protons of trimethylsilylmethyl groups was
The bulky arylamine 2,6-iPr2C6H3NHSiiPr3 was synthe-
sized by silylation of 2,6-iPr2C6H3NH2 with SiiPr3Cl.
Deprotonation of 2,6-iPr2C6H3NH2 with 1 equiv. of n-
BuLi in THF at room temperature, followed by reaction
of SiiPr3Cl for three days gave 2,6-iPr2C6H3NHSiiPr3 as
colorless oil in 59% isolated yield (Scheme 1). Lithiation
of 2,6-iPr2C6H3NHSiiPr3 with n-BuLi at 1:1 molar ratio
in THF produced the lithium salt 2,6-iPr2C6H3NSiiPr3Li
in nearly quantitative yield, therefore, 2,6-iPr2C6H3N-
SiiPr3Li could be used formed in situ.
When THF slurry of anhydrous YCl3 reacted with one
equiv. of 2,6-iPr2C6H3NSiiPr3Li at room temperature,
after workup, an anionic mono-arylamido-ligated yttrium
dichloride complex {[2,6-iPr2C6H3NSiiPr3]YCl2 (THF)}2-
[LiCl(THF)2] (1) was obtained in 90% isolated yield,
as illustrated in Scheme 2. Alkylation of 1 with 4 equiv.
of LiCH2SiMe3 in THF at room temperature could lead
1
observed at ꢀ0.67 in the H NMR spectra. No Y–H cou-
pling (JY–H) was observed as that in an analogous complex
of [2,6-iPr2C6H3NSiMe3]Y(CH2SiMe3)2(THF) [5]. In 13C
NMR spectrum of 2, the methylene carbons bonded to
yttrium were reported as a doublet with a coupling con-
stant of JY–C = 32 Hz, which is much smaller than that
observed in [2,6-iPr2C6H3NSiMe3]Y(CH2SiMe3)2(THF)
(43.5 Hz) [5].
Structures of 1 and 2 were determined by a single-crystal
X-ray diffraction study. Crystals of 1 suitable for X-ray dif-
fraction were grown from hexane at ꢀ30 ꢁC. An OTEPT
diagram depicting the molecular structure of 1 is shown
in Fig. 1. Detailed crystal and structural refinement data
are listed in Table 1, selected bond lengths and bond angles
are given in Table 2. As shown in Fig. 1, the structure of 1
in the crystal is consistent with the above-mentioned spec-
troscopic data in solution. Complex 1 consists of two moi-
eties, i.e., one is dinuclear part containing two yttrium
centers bridged by three l-chlorine atoms (Cl(1), Cl(2),
and Cl(3)), the other is Li(THF)2 cation, they are bonded
together through three l-chlorine atoms (Cl(1), Cl(2),
and Cl(4)). In this case, Cl(1) and Cl(2) are l3-chlorine
atoms, Cl(3) and Cl(4) are l2-chlorine atoms. Each yttrium
to
a
mono(arylamido) yttrium tris(alkyl) complex
[2,6-iPr2C6H3NSiiPr3]Y(CH2Si Me3)3Li(THF)2 (2) in 56%
isolated yield (Scheme 3).
The formulae of 1 and 2 were confirmed by NMR, ele-
mentary analysis, and X-ray structural determination.
Both complexes are colorless in the solid state, extremely
sensitive to air and moisture, and thermally stable at room
temperature. They have perfect solubility in THF, toluene,
and even in hexane.
The diamagnetic yttrium complexes of 1 and 2 showed
well-resolved NMR spectra. Ligand redistribution was
THF
THF
Li
Cl
i
Li
Si Pr
3
Cl
Cl
Cl
N
i
Si Pr
3
N
Y
THF, r.t.
- LiCl
+
YCl
1/2
3
Y
N
Cl
i
THF
Si Pr
3
THF
1
Scheme 2.

B. Shen et al. / Inorganica Chimica Acta 361 (2008) 1255–1260
1257
THF
THF
Li
Cl
Cl
Cl
Cl
SiiPr3
N
toluene/hexane, r.t.
- LiCl
N
Y
4 LiCH2SiMe3
+
Y
Cl
SiiPr3
THF
THF
CH2SiMe3
CH2SiMe3
1
Y
N
H2
C
Si
2
SiiPr3
Li
THF
THF
2
Scheme 3.
C6H3Me2-2,6)2(l-Cl)(NHC6H3Me2-2,6)4- (THF)2] (2.26(2)–
˚
2.30(2) A) [4g], when the differences in radii and coordina-
tion number are considered [7]. The bond lengths of Y–Cl
˚
lie in the range 2.559–2.984 A. Although the bond modes
of Y(1)–Cl(4) and Y(2)–Cl(5) are bridged and terminal,
respectively, the bond lengths are almost matched
˚
(2.575(3) for Y(1)–Cl(4) and 2.559(3) A for Y(2)–Cl(5)).
Crystals of 2 suitable for X-ray diffraction were grown
from toluene at ꢀ30 ꢁC. An OTEPT diagram depicting
the molecular structure of 2 is shown in Fig. 2. Detailed
crystal and structural refinement data are listed in Table
1, selected bond lengths and bond angles are given in Table
3. As shown in Fig. 2, 2 is a mono-arylamido-ligated
yttrium tris(alkyl) complex, which is incorporated by
Fig. 1. ORTEP structure of 1 (thermal ellipsoids at the 30% level,
hydrogen atoms are omitted for clarity).
center is six-coordinated by one arylamido ligand, one
THF molecule, four chlorine atoms, forming a distorted
octahedral. Although both yttrium centers in 1 share
Cl(1), Cl(2), and Cl(3) atoms, the significant coordination
difference between Y(1) and Y(2) is that Y(1) contains a
l2-chlorine atom (Cl(4)) connecting Li cation, while Y(2)
possesses a terminal chlorine atom (Cl(5)). The bond
lengths of Y(1)–N(1) and Y(2)–N(2) in 1 are nearly equal
˚
(2.229(7) and 2.228(7) A, respectively). These two Y–N
bond length values are identical to those in [2,20-bis-
((tert-butyldimethylsily)amido)-6,60-dimethylbiphenyl]YCl
(THF)2 (av. 2.25 A) [6], [2,6-iPr2C6H3NSiMe3]2Nd-
˚
i
˚
Cl(THF) (2.276 (2) and 2.264(2) A) [4h], [2,6- Me2C6-
H3NSiMe3]2Nd(l-Cl)2Li- (THF)2 (2.318 (3) and 2.282(3)
˚
A) [4h], [{l2-p-(Me3SiN)2C6H4}YbCl(THF)2]2 (2.174(6)
Fig. 2. ORTEP structure of 2 (thermal ellipsoids at the 30% level,
hydrogen atoms are omitted for clarity).
˚
and 2.173(6) A) [4b], and [K(DME)2(THF)3][Y2(l-NH-

1258
B. Shen et al. / Inorganica Chimica Acta 361 (2008) 1255–1260
Table 1
Summary of crystallographic data of complex 1 and 2
1
2
Formula
C29H54Cl2. 5Li0.5NO2SiY
657.83
0.45 · 0.30 · 0.30
Triclinic
C41H87LiNO2Si4Y
834.33
Molecular weight
Crystal size (mm3)
Crystal system
Space group
0.30 · 0.20 · 0.15
Monoclinic
P2ð1Þ=c
19.129(5)
14.501(4)
18.821(5)
90
95.597(4)
90
5196(2)
ꢀ
P1
˚
a (A)
15.215(3)
15.475(3)
18.441(4)
103.082(3)
95.757(4)
112.670(3)
3816.5(14)
4
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V (A )
Z
4
q (g cmꢀ3
)
1.145
1.756
173(1)
1.067
1.243
173(1)
l (Mo Ka) (mmꢀ1
T (K)
)
h range (ꢁ)
1.48–25.09
18523
13195 [Rint = 0.0465]
702
1.77–25.09
24620
9168 [Rint = 0.1039]
493
Number of reflections collected
Number of reflections with I(>2r(I))
Number of parameters
R1 (I > 2r(I))
0.0682
0.0507
wR2 (I > 2r(I))
0.2098
0.0485
Goodness-of-fit
Maximum/minimum residual density (e A
1.011
1.459/ꢀ0.722
0.742
0.614/ꢀ0.356
ꢀ3
˚
)
Table 2
˚
yttrium moiety is connected with Li(THF)2 cation by the
methylene carbon of CH2SiMe3. The bond length of
Bond lengths (A) and angles (ꢁ) for complex 1
˚
Y(1)–N(1)
Y(1)–O(1)
Y(1)–Cl(4)
Y(1)–Cl(1)
Y(1)–Cl(3)
Y(1)–Cl(2)
Y(1)–Y(2)
Y(2)–N(2)
Y(2)–O(2)
2.229(7)
2.343(6)
2.575(3)
2.650(3)
2.708(3)
2.963(3)
3.9521(14)
2.228(7)
2.317(6)
Y(2)–Cl(5)
Y(2)–Cl(2)
Y(2)–Cl(3)
Y(2)–Cl(1)
Cl(1)–Li(1)
Cl(2)–Li(1)
Cl(4)–Li(1)
O(4)–Li(1)
O(3)–Li(1)
2.559(3)
2.649(3)
2.698(2)
2.984(3)
2.67(4)
2.62(3)
2.70(5)
2.03(5)
2.05(4)
Y–N (2.259(3) A) in 2 is identical to those in {[Me2Si-
˚
(NPh)2]Yb(C5H5)2}{Li(DME)3} (2.250(4) and 2.232(7) A)
[4a], {[Me2Si(NPh)2]Yb(MeC5H5)2}{Li(DME)3} (2.242(4)
˚
and 2.254(4) A) [4a], but is slightly longer than those in 1
i
˚
( av. 2.228 A), [2,6- Pr2C6H3NSiMe3]Y(CH2SiMe3)2(THF)
(2.190(2) A) [5], [2,6-iPr2C6H3NSiMe3]2YbCH3(l-CH3)-
Li(THF)3 (2.224 (6) and 2.227(6) A) [4d]. The average
˚
˚
˚
bond length of Y–CH2SiMe3 (2.389 A) (refers to Y(1)–
N(1)–Y(1)–O(1)
N(1)–Y(1)–Cl(4)
O(1)–Y(1)–Cl(4)
N(1)–Y(1)–Cl(1)
O(1)–Y(1)–Cl(1)
Cl(4)–Y(1)–Cl(1)
N(1)–Y(1)–Cl(3)
O(1)–Y(1)–Cl(3)
Cl(4)–Y(1)–Cl(3)
Cl(1)–Y(1)–Cl(3)
N(1)–Y(1)–Cl(2)
O(1)–Y(1)–Cl(2)
Cl(4)–Y(1)–Cl(2)
Cl(1)–Y(1)–Cl(2)
Cl(3)–Y(1)–Cl(2)
N(2)–Y(2)–O(2)
N(2)–Y(2)–Cl(5)
O(2)–Y(2)–Cl(5)
N(2)–Y(2)–Cl(2)
O(2)–Y(2)–Cl(2)
Cl(5)–Y(2)–Cl(2)
106.5(2)
104.3(2)
95.56(16)
104.33(19)
147.21(16)
87.43(9)
N(2)–Y(2)–Cl(3)
O(2)–Y(2)–Cl(3)
Cl(5)–Y(2)–Cl(3)
Cl(2)–Y(2)–Cl(3)
N(2)–Y(2)–Cl(1)
O(2)–Y(2)–Cl(1)
Cl(5)–Y(2)–Cl(1)
Cl(2)–Y(2)–Cl(1)
Cl(3)–Y(2)–Cl(1)
Y(2)–Cl(3)–Y(1)
Y(1)–Cl(1)–Li(1)
Y(1)–Cl(1)–Y(2)
Li(1)–Cl(1)–Y(2)
Li(1)–Cl(2)–Y(2)
Li(1)–Cl(2)–Y(1)
Y(2)–Cl(2)–Y(1)
O(4)–Li(1)–O(3)
Cl(2)–Li(1)–Cl(1)
Cl(4)–Li(1)–Cl(1)
Cl(2)–Li(1)–Y(1)
Cl(4)–Li(1)–Y(1)
102.4(2)
C(22) and Y(1)–C(26)) is comparable to that in
85.06(18)
152.92(10)
79.27(8)
175.4(2)
74.75(16)
79.87(9)
72.05(7)
73.15(7)
93.94(7)
85.0(11)
88.87(7)
86.4(8)
94.8(13)
79.9(8)
89.34(7)
98.9(15)
77.9(8)
i
˚
[2,6- Pr2C6H3NSiMe3]Y(CH2SiMe3)2(THF) (2.367 A) [5].
˚
The bond length of Y(1)–C(30) is ca. 0.1 A longer than
those of Y(1)–C(22) and Y(1)–C(26), this contributes to
that C(30) is a bridging carbon connecting the yttrium
center and Li cation. The bond angle of Y(1)–C(30)–Li(1)
is 149.4(3)ꢁ, which is approximately 30ꢁ smaller than
that in [2,6-iPr2C6H3NSiMe3]2YbCH3(l-CH3)Li(THF)3
(178.8(5)ꢁ) [4d].
104.9(2)
82.92(16)
149.95(9)
78.60(8)
176.60(19)
76.57(15)
76.65(8)
72.38(7)
73.80(7)
106.3(2)
104.6(2)
Table 3
˚
Selected bond lengths (A) and angles (ꢁ) for complex 2
Y(1)–N(1)
Y(1)–C(26)
Y(1)–C(22)
Y(1)–C(30)
2.259(3)
2.373(3)
2.405(3)
2.490(4)
Li(1)–O(1)
Li(1)–O(2)
Li(1)–C(30)
1.862(8)
1.885(8)
2.269(8)
90.10(18)
106.28(19)
146.15(17)
90.48(9)
84.6(10)
54.3(5)
45.6(5)
N(1)–Y(1)–C(26)
N(1)–Y(1)–C(22)
C(26)–Y(1)–C(22)
N(1)–Y(1)–C(30)
C(26)–Y(1)–C(30)
118.78(11)
108.99(11)
102.46(11)
116.73(13)
101.07(14)
C(22)–Y(1)–C(30)
O(1)–Li(1)–O(2)
O(1)–Li(1)–C(30)
O(2)–Li(1)–C(30)
Y(1)–C(30)–Li(1)
107.39(14)
106.9(4)
125.9(4)
126.9(4)
149.4(3)
1 equiv. of [Li(THF)2]+. The yttrium center is four-coordi-
nated by one arylamido ligand and three CH2SiMe3
groups, forming a distorted tetrahedral geometry. The

B. Shen et al. / Inorganica Chimica Acta 361 (2008) 1255–1260
1259
3. Conclusion
2 H, CH(CH3)2), 7.06–7.11 (3 H, C6H3). 13C NMR
(C6D6, 100 MHz): d 13.97, 18.82, 23.74, 28.42, 123.30,
123.81, 140.82, 143.79. Anal. Calc. for C21H39NSi: C,
75.60; H, 11.78; N, 4.20. Found: C, 75.49; H, 11.71; N,
4.09%.
In summary, we have synthesized an anionic yttrium
dichloride bearing a bulky arylamido ligand, {[2,6-iPr2-
C6H3NSiiPr3]YCl2(THF)}2[LiCl(THF)2] (1), which was
obtained from the salt metathesis reaction of anhydrous
YCl3 with 1 equiv. amount of 2,6-iPr2C6H3NSiiPr3Li in
THF at room temperature. Further treatment of 1 with
4 equiv. of LiCH2SiMe3 at room temperature could lead
to an anionic mono(arylamido) yttrium tris(alkyl) complex
[2,6-iPr2C6H3NSiiPr3]Y(CH2SiMe3)3Li(THF)2 (2).
4.3. Synthesis of {[2,6-iPr2C6H3NSiiPr3]YCl2(THF)}2-
[LiCl(THF)2]
To a 30 mL of THF slurry of YCl3 (1.05 g, 5.38 mmol)
was added 2,6-iPr2C6H3NSiiPr3Li (5.38 mmol), which was
prepared in situ from the reaction of 2,6-iPr2C6H3NHSiiPr3
(1.80 g, 5.38 mmol) with n-BuLi (5.38 mmol, 3.4 mL) in
THF at room temperature. The mixture was stirred for
24 h at room temperature. The resulting reaction mixture
was dried in vacuo, and the residue was extracted with
30 mL of hexane. After filtration, the pale yellow solution
was concentrated, and cooled at ꢀ30 ꢁC overnight to
give {[2,6-iPr2C6H3NSiiPr3]YCl2(THF)}2[LiCl(THF)2] as
colorless cubic-shaped crystals (3.2 g, 4.86 mmol, 90%
4. Experimental
4.1. Materials and procedures
All manipulations were performed under pure argon
with rigorous exclusion of air and moisture using standard
Schlenk techniques and a Mikrouna glovebox. Solvents
(toluene, tetrahydrofuran, and hexane) were distilled from
sodium/benzophenone ketyl, degassed by the freeze–pump-
thaw method, and dried over fresh Na chips in the glove-
box. 2,6-iPr2C6H3NHSiiPr3 was prepared by the reaction
1
yield). H NMR (THF-d8, 400 MHz): d 0.97 (d, 36H, JH–
H = 8.0 Hz, NSi[(CH3)2CH]3), 0.99 (m, 6 H, d, CH(CH3)2),
1.06 (d, 12H, JH–H = 6.4 Hz, CH(CH3)2), 1.09 (d, 12H,
JH–H = 6.4 Hz, CH(CH3)2), 1.69 (m, 16H, THF), 3.53
(m, 16H, THF), 3.94 (m, 4H, CH(CH3)2), 6.64 (d, 4 H,
m-PhH), 6.84 (t, 2H, p-PhH). 13C NMR (THF-d8,
of 2,6-iPr2C6H3NHLi with Pr3SiCl in THF at room tem-
i
perature. 2,6-iPr2C6H3NHLi was synthesized by the reac-
tion of 2,6-iPr2C6H3NH2 with n-BuLi in THF according
to the literature [4d,4h]. n-BuLi (1.6 M solution in hexane),
100 MHz):
d
15.84 (NSi[(CH3)2CH]3), 19.58 (NSi-
2,6-iPr2C6H3NH2 and Pr3SiCl were obtained from Acros,
[(CH3)2CH]3), 22.51 (CH(CH3)2), 25.38 (THF-b-C), 26.09
(CH(CH3)2), 67.29 (THF-a-C), 121.66, 123.86, 141.52,
155.79 (C6H3). Anal. Calc. for C29H54Cl2. 5Li0.5NO2SiY:
C, 52.95; H, 8.29; N, 2.13. Found: C, 52.54; H, 8.77; N,
1.96%.
i
and used without purification. Anhydrous YCl3 was pur-
chased from STREM. LiCH2SiMe3 (1 M solution in pen-
tane) was obtained from Aldrich, and used as powder
after drying up the solvent under vacuum. C6D6 and
THF-d8 were obtained from ISOTEC, and were dried by
Na chips in the glovebox.
4.4. Synthesis of [2,6-iPr2C6H3 NSiiPr3]Y(CH2Si
Me3)3Li(THF)2
Samples of yttrium complexes for NMR spectroscopic
measurements were prepared in the glovebox using J.
Young valve NMR tubes. H and 13C NMR spectra were
To
a
20 mL of hexane/toluene solution of
1
recorded on a Unity Inova-400 spectrometer at 25 ꢁC. Car-
bon, hydrogen, and nitrogen analyses were performed by
direct combustion on a Carlo-Erba EA-1110 instrument,
quoted data are the average of at least two independent
determinations.
{[2,6-iPr2C6H3NSiiPr3]YCl2 (THF)}2[LiCl(THF)2] (1.32 g,
2.0 mmol) was added slowly LiCH2SiMe3 (0.76 g,
8.0 mmol) in hexane at room temperature. The mixture
was stirred for 1 h at room temperature. The resulting solu-
tion was dried up, and the residue was extracted with tolu-
ene. After concentration, the toluene solution was cooled
at ꢀ30 ꢁC overnight to give[2,6-iPr2C6 H3NSiiPr3]Y(CH2Si
Me3)2Li(CH2SiMe3)(THF)2 as colorless cubic-shaped
crystals (1.4 g, 1.2 mmol, 56% yield). 1H NMR (C6D6,
400 MHz): d ꢀ0.67 (s, 6 H, CH2SiMe3), 0.34 (s, 9H,
CH2SiMe3), 0.36 (s, 18H, CH2SiMe3), 1.33 (d, 18H,
JH–H = 5.2 Hz, SiCH(CH3)2), 1.35 (d, 6H, JH–H = 6.3 Hz,
4.2. Synthesis of 2,6-iPr2C6H4NHSiiPr3
To a 50 mL of THF solution of 2,6-iPr2C6H4NHLi
(68 mmol), which was prepared from the reaction of
2,6-iPr2C6H4NH2 with 1 equiv. of n-BuLi in a mixture solu-
tion of THF and hexane, added a THF solution of iPr3SiCl
(13.23 g, 68 mmol) at room temperature. The reaction mix-
ture was stirred at room temperature for 3 days, and it
changed from clear orange solution to cloudy slurry solu-
tion. After drying up the solvents in vacuum, the residue
oil product was distilled under 190 ꢁC/5 mmHg to give
2,6-iPr2C6H4NHSiiPr3 as colorless oil (13.5 g, 59%). 1H
NMR (C6D6, 400 MHz): d 1.10 (d, 18 H, CH(CH3)2),
1.26 (d, 12 H, CH(CH3)2), 2.42 (b s, 1 H, N-H), 3.55 (m,
CH(CH3)2), 1.38 (m, 8H, THF), 1.42 (d, 6H, JH–H
=
6.3 Hz, CH(CH3)2), 1.51 (m, 3H, SiCH(CH3)2), 3.25
(m, 8H, THF), 4.16 (m, 2 H, CH(CH3)2), 6.88 (t, 1 H,
p-PhH), 7.04 (d, 2H, m-PhH). 13C NMR (C6D6,
100 MHz): d 5.02 (CH2Si Me3), 5.11 (CH2SiMe3), 16.12
(NSi[(CH3)2CH]3),
20.91
(NSi[(CH3)2CH]3),
25.80
((CH3)2CH), 27.08 (THF-b-C), 28.16 (CH(CH3)2), 35.04
(JY–C = 32 Hz, CH2SiMe3), 69.30 (THF-a-C), 121.71,

1260
B. Shen et al. / Inorganica Chimica Acta 361 (2008) 1255–1260
125.04, 146.01, 148.75 (C6H3). Anal. Calc. for C41H87Li-
NO2Si4Y: C, 59.02; H, 10.53; N, 1.68. Found: C, 58.70;
H, 10.29; N, 1.99%.
ccdc.cam.ac.uk. Supplementary data associated with this
article can be found, in the online version, at
doi:10.1016/j.ica.2007.08.010.
4.5. X-ray structural determination
References
[1] Selected review (a) J. Gromada, J.F. Carpentier, A. Mortreux, Coord.
Chem. Rev. 248 (2004) 397;
A suitable pale yellow crystal was sealed in a thin-walled
capillary under a microscope in the glovebox. Data
collection was performed on a Bruker SMART APEX dif-
fractometer with a CCD area detector using graphite-
(b) Z.M. Hou, Y. Wakatsuki, Coord. Chem. Rev. 231 (2002) 1;
(c) H. Schumann, J.A. Meese-Marktscheffel, L. Esser, Chem. Rev. 95
(1995) 865.
˚
monochromated Mo Ka radiation (k = 0.71069 A). The
[2] Selected review (a) V.C. Gibson, K. Spitzmesser, Chem. Rev. 103
(2003) 283;
determination of crystal class and unit cell was carried
out by SMART program package [8]. The raw frame data
were processed using SAINT [9] and SADABS [10] to yield
the reflection data file. The structure was solved using
SHELXTL program [11]. Refinement was performed on F2
anisotropically for all the non-hydrogen atoms by the
full-matrix least-squares method. The analytical scattering
factors for neutral atoms were used throughout the analy-
sis. Hydrogen atoms were placed at the calculated positions
and were included in the structure calculation without fur-
ther refinement of the parameters.
(b) F.T. Edelmann, D.M.M. Freckmann, H. Schumann, Chem. Rev.
102 (2002) 1851.
[3] Reviews (a) M.F. Lappert, P.P. Power, A.R. Sanger, R.C. Srivastava,
Metal and Metalloid Amides, Ellis Norwood Ltd., Chichester,
England, 1980;
(b) R. Kempe, Angew. Chem. Int. Ed. 39 (2000) 468;
(c) R. Kempe, Eur. J. Inorg. Chem. (2003) 791, see also reference [2].
[4] For examples of bis- or tris(arylamido) rare earth metal complexes,
see: (a) L.Y. Zhou, Y.M. Yao, C. Li, Y. Zhang, Q. Shen,
Organometallics 25 (2006) 2880;
(b) B. Zhao, H.H. Li, Q. Shen, Y. Zhang, Y.M. Yao, C.R. Lu,
Organometallics 25 (2006) 1824;
(c) P.B. Hitchcock, Q.G. Huang, M.F. Lappert, X.H. Wei, J. Mater.
Chem. 14 (2004) 3266;
(d) Y.J. Luo, Y.M. Yao, W.J. Li, J.L. Chen, Z.Q. Zhang, Y. Zhang,
Q. Shen, J. Organomet. Chem. 679 (2003) 125;
(e) P.B. Hitchcock, A.V. Khvostov, M.F. Lappert, A.V. Protchenko,
J. Organomet. Chem. 647 (2002) 198;
(f) P.W. Roesky, Organometallics 21 (2002) 4756;
(g) D.R. Click, B.L. Scott, J.G. Watkin, Chem. Commun. (1999)
633;
Acknowledgements
This work was partly supported by the National Natural
Science Foundation of China (20604023), and Zhejiang
Provincial Natural Science Foundation (Y406301). The
authors are grateful for Dr. Masayoshi Nishiura in Orga-
nometallic Chemistry Laboratory, RIKEN, Japan, for X-
ray structural analysis help.
(h) W.J. Evans, M.A. Ansari, J.W. Ziller, Inorg. Chem. 35 (1996)
5435;
(i) H. Schumann, J. Winterfeld, E.C.E. Rosenthal, H. Hemling, L.
Esser, Z. Anorg. Allg. Chem. 621 (1995) 122.
[5] Y.J. Luo, M. Nishiura, Z.M. Hou, J. Organomet. Chem. 692 (2007)
536.
Appendix A. Supplementary material
[6] T.I. Gountchev, T.D. Tilley, Organometallics 18 (1999) 2896.
[7] R.D. Shannon, Acta Crystallogr., Sect. A 32 (1976) 751.
[8] SMART Software Users Guide, Version 4.21; Bruker AXS, Inc.:
Madison, WI, 1997.
[9] SAINT+, Version 6.02; Bruker AXS, Inc.: Madison, WI, 1999.
[10] G.M. Sheldrick, SADABS, Bruker AXS, Inc., Madison, WI, 1998.
[11] G.M. Sheldrick, SHELXTL, Version 5.1, Bruker AXS, Inc., Madison,
WI, 1998.
CCDC 640090 and 640091 contain the supplementary
crystallographic data for 1 and 2. These data can be
obtained free of charge via http://www.ccdc.cam.ac.uk/
conts/retrieving.html, or from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK; fax: (+44) 1223-336-033; or e-mail: deposit@