Reaction of Me
2Si(Me
2NCH
2CH
2C
9H
6)Cl with 1 equiv of
t-BuNHLi yielded Me
2Si(Me
2NCH
2CH
2C
9H
6)(
t-BuNH) (
1). Treatment of Me
2NCH
2CH
2C
9H
7 with 1 equiv of
n-BuLi,followed by reaction with an excess of Me
3SiCl, produced Me
2NCH
2CH
2C
9H
6SiMe
3 (
2) in79% yield. Interaction of YbCl
3 with 3 equiv of (Me
3Si)
2NLi in THF, after workup, producedthe tetracoordinate ytterbium(III) amide [(Me
3Si)
2N]
3Yb
III(
![](/images/entities/mgr.gif)
-Cl)Li(THF)
3 (
3) in 85% yield.Treatment of
3 with 2 equiv of
1 gave the ytterbium(II) complex [
5:
1-Me
2Si(Me
2NCH
2CH
2C
9H
5)(
t-BuNH)]
2Yb
II (
4) in 58% yield via a reductive reaction. To get some insight intothe reaction, several reactions were initiated to study the effects of the
t-BuNH group, silylgroup, and
N,
N-dimethylaminoethyl group of the indene compounds, effects of coordinateClLi(THF)
3 in
3, and temperature effect on the reductive reaction. Treatment of
3 with 2equiv of
2 afforded (
5:
1-Me
2NCH
2CH
2C
9H
5SiMe
3)
2Yb
II (
5) in 52% yield. Interaction of
3with 2 equiv of Me
2NCH
2CH
2C
9H
7 produced a ytterbium(II) complex (
5:
1-Me
2NCH
2CH
2C
9H
6)
2Yb
II (
6) in 63% yield. Treatment of the ytterbium(III) complex [(Me
3Si)
2N]
3Yb
IIIwith 2 equiv of Me
2NCH
2CH
2C
9H
7 also afforded the ytterbium(II) complex (
5:
1-Me
2NCH
2CH
2C
9H
6)
2Yb
II (
6) in 62% yield, which provides an alternate method for the preparation of
6. Treatment of
3 with 2 equiv of indene(C
9H
8) produced the ytterbium(III) complex (
5-C
9H
7)
2Yb
IIIN(SiMe
3)
2 (
7). Treatment of
3 with 1 equiv of 1,2-bis(indenyl)ethane also producedthe ytterbium(III) complex
meso-[ethylenebis(
5-indenyl)ytterbium
III bis(trimethylsily)amide((EBI)Yb
IIIN(SiMe
3)
2) (
8). All the compounds were fully characterized by spectroscopicmethods and elemental analyses. Complexes
3,
4,
5,
6, and
8 were additionally characterizedby a single-crystal X-ray diffraction study. The formation pathway for the ytterbium(II)complexes is proposed. The study showed that ytterbuim(II) complexes
4,
5, and
6 canfunction as single-component MMA polymerization catalysts with good activity.