A new heteroatom coordination promoted homolysis of the Yb-N bond. Synthesis and structural characterization of a new class of ytterbium(II) and ytterbium(III) complexes with amido and indenyl ligands and catalytic activities of ytterbium(II) complexes

作者：Sheng EH; Wang SW^*; Yang GS; Zhou SL; Cheng L; Zhang KH; Huang ZX

来源：Organometallics, 2003, 22(4): 684-692.

DOI：10.1021/om020562m

Reaction of Me2Si(Me2NCH2CH2C9H6)Cl with 1 equiv of t-BuNHLi yielded Me2Si(Me2NCH2CH2C9H6)(t-BuNH) (1). Treatment of Me2NCH2CH2C9H7 with 1 equiv of n-BuLi, followed by reaction with an excess of Me3SiCl, produced Me2NCH2CH2C9H6SiMe3 (2) in 79% yield. Interaction of YbCl3 with 3 equiv of (Me3Si)(2)NLi in THF, after workup, produced the tetracoordinate ytterbium(III) amide [(Me3Si)(2)N](3)Yb-III(mu-Cl)Li(THF)(3) (3) in 85% yield. Treatment of 3 with 2 equiv of 1 gave the ytterbium(II) complex [eta(5):eta(1)-Me2Si(Me2NCH2CH2C9H5)(t-BuNH)](2)Yb-II (4) in 58% yield via a reductive reaction. To get some insight into the reaction, several reactions were initiated to study the effects of the t-BuNH group, silyl group, and N,N-dimethylaminoethyl group of the indene compounds, effects of coordinate ClLi(THF)(3) in 3, and temperature effect on the reductive reaction. Treatment of 3 with 2 equiv of 2 afforded [eta(5):eta(1)-Me2NCH2CH2C9H5SiMe3](2)Yb-II (5) in 52% yield. Interaction of 3 with 2 equiv of Me2NCH2CH2C9H7 produced a ytterbium(II) complex (eta(5):eta(1)-Me2NCH2CH2C9H6)(2)Yb-II (6) in 63% yield. Treatment of the ytterbium(III) complex [(Me3Si)(2)N](3)Yb-III with 2 equiv of Me2NCH2CH2C9H7 also afforded the ytterbium(II) complex (eta(5):eta(1)-Me2NCH2CH2C9H6)(2)Yb-II (6) in 62% yield, which provides an alternate method for the preparation of 6. Treatment of 3 with 2 equiv of indene(C9H8) produced the ytterbium(III) complex (eta(5)-C9H7)(2)(YbN)-N-III(SiMe3)(2) (7). Treatment of 3 with I equiv of 1,2-bis(indenyl)ethane also produced the ytterbium(III) complex meso-[ethylenebis(eta(5)-indenyl)ytterbium(III) bis(trimethylsily)amide ((EBI)(YbN)-N-III(SiMe3)(2)) (8). All the compounds were fully characterized by spectroscopic methods and elemental analyses. Complexes 3, 4, 5, 6, and 8 were additionally characterized by 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 can function as single-component MMA polymerization catalysts with good activity.

• 出版日期2003-2-17
• 单位安徽师范大学; 中国科学院福建物质结构研究所