Abstract
Complexes [Zr(η2-Me3SiC/CSiMe3)(η5-C5Me4R)2], where R = Me (5), H (6), and SiMe3 (7), reacted smoothly with terminal alkynes HC/CR'' (R'' = CMe3, SiMe3, ferrocenyl (Fc), and Ph) to give agostic alkenyl-alkynyl complexes [Zr(η1-C/CR''){η3-C(SiMe3)=CH(SiMe3)}(η5-C5Me4R)2], R/R'' = Me/CMe3 (5a), Me/SiMe3 (5b); H/CMe3 (6a), H/SiMe3 (6b), H/Fc (6c), H/Ph (6d); SiMe3/CMe3 (7a), and SiMe3/Fc (7c). Complex 7a formed from 7 and HC/CCMe3 dimerized t-butylethyne to give pure head-to-tail dimer Me3C(=CH2)CC/CCMe3 until all the alkyne was consumed and then it restored complex 7.
Complex 7 reacted with 1-hexyne, phenylethyne and (trimethylsilyl)ethyne to give alkenyl-alkynyl complexes; however, evaporation of the alkynes in vacuum restored 7, and neither of these alkynes dimerized.