532959-17-4Relevant academic research and scientific papers
Tethered olefin studies of alkene versus tetraphenylborate coordination and lanthanide olefin interactions in metallocenes
Evans, William J.,Perotti, Jeremy M.,Brady, Jason C.,Ziller, Joseph W.
, p. 5204 - 5212 (2003)
The tethered olefin cyclopentadienyl ligand, [(C5Me4)SiMe2(CH2CH= CH2)]-, forms unsolvated metallocenes, [(C5Me4)SiMe2(CH2CH= CH2)]2Ln (Ln = Sm, 1; Eu, 2; Yb, 3), from [(C5Me4)SiMe2(CH2CH= CH2)]K and Lnl2(THF)2 in good yield. Each complex in the solid state has both tethered olefins oriented toward the Ln metal center with the Ln-C(terminal alkene carbon) distances 0.2-0.3 A shorter than the Ln-C(internal alkene carbon) distances. The olefinic C-C bond distances in 2 and 3, 1.328(4) and 1.328(5) A, respectively, are normal. Like its permethyl analogue, (C5Me5)2Sm(THF)2, complex 1 reductively couples CO2 to form the oxalate-bridged dimer {[(C5Me4)SiMe2(CH2CH= CH2)]2Sm}2(μ-η2: η2-O2CCO2), 4, in which the tethered olefins are noninteracting substituents. Complex 1 reacts with AgBPh4 to form an unsolvated cation that has the option of coordinating [BPh4]- or a pendant olefin, a competition common in olefin polymerization catalysis. The structure of {[(C5Me4)SiMe2(CH2 CH=CH2)]2Sm}[BPh4], 5, shows that both pendant olefins are located near samarium rather than the [BPh4]- counterion.
