Silicon–Carbon bond cleavage reactions of Ansa tungstenocene compounds: The [Me 2 Si] bridge as a site for metallocene functionalization
Author(s) -
C.E. Zachmanoglou,
Hyosun Lee,
Seung Ho Jang,
Keliang Pang,
Gerard Parkin
Publication year - 2008
Publication title -
proceedings of the national academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.0803089105
Subject(s) - chemistry , reagent , metallocene , surface modification , cleavage (geology) , bond cleavage , stereochemistry , yield (engineering) , medicinal chemistry , polymerization , organic chemistry , catalysis , materials science , fracture (geology) , metallurgy , composite material , polymer
[Me(2)Si(Cp(Me(2)))(2)]W(H)Cl is obtained via reaction of WCl(6) with a mixture of [Me(2)Si(Cp(Me(2)))(2)]Li(2) and NaBH(4), from which the dichloride [Me(2)Si(Cp(Me(2)))(2)]WCl(2) is obtained via treatment with CHCl(3). [Me(2)Si(Cp(Me(2)))(2)]WCl(2) provides a means to access other ansa tungstenocene compounds, such as [Me(2)Si(Cp(Me(2)))(2)]WH(2), [Me(2)Si(Cp(Me(2)))(2)]WMe(2), and [Me(2)Si(Cp(Me(2)))(2)]WCO. Of most interest, the reactions of [Me(2)Si(Cp(Me(2)))(2)]W(H)Cl with organolithium reagents do not yield simple ansa tungstenocene derivatives. Specifically, the reactions of [Me(2)Si(Cp(Me(2)))(2)]W(H)Cl with MeLi, Bu(n)Li, or PhLi result in the formation of mixed-ring tungstenocene compounds resulting from C-Si cleavage and functionalization of the ansa bridge, namely (Cp(Me(2)))(eta(5),kappa(1)-C(5)H(2)Me(2)SiMe(2)CH(2))WH, (Cp(Me(2)))[eta(5),kappa(1)-C(5)H(2)Me(2)Si(Me)(Bu(n))CH(2)]WH, and (Cp(Me(2)))[eta(5),kappa(1)-C(5)H(2)Me(2)SiMe(2)(C(6)H(4))]WH, respectively. In contrast to the C-Si cleavage achieved by MeLi, Bu(n)Li, and PhLi, the ansa bridge of [Me(2)Si(Cp(Me(2)))(2)]W(H)Cl is inert to Bu(t)Li and the product obtained is the fulvene ("tuck-in") complex [Me(2)Si(Cp(Me(2)))(eta(6)-C(5)MeH(2)CH(2))]WH derived from dehydrohalogenation.
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