Solution and solid–gas reactivity of unsaturated [RuCp(tmeda)]+ (tmeda=Me2NC2H4NMe2)

The coordinatively unsaturated complex [RuCp(tmeda)]+ has been prepared by the reaction of [RuCp(tmeda)Cl] with NaBAr′4 (Ar′=3,5-C6H3(CF3)2) in fluorobenzene. The PF6− salt of [RuCp(tmeda)]+ is prepared by heating [RuCp(tmeda)(CH3CN)]PF6 at 150°C under reduced pressure (10−2 atm). The X-ray crystal structure of [RuCp(tmeda)]+ as the BAr′4 salt has been determined showing the absence of any agostic interactions between ruthenium and the CH bonds of the diamine ligand, and only minor deviations from the planar geometry at Ru. [RuCp(tmeda)]+ reacts readily with the gases H2, CH2CH2, CHFCH2, HCCH, CO, HCl, N2, and O2 at low temperature to give [RuCp(tmeda)(η2-H2)]+, [RuCp(tmeda)(η2-CH2CH2)]+, [RuCp(tmeda)(η2-CHFCH2)]+, [RuCp(tmeda)(η2-HCCH)]+, [RuCp(tmeda)(CO)]+, [RuCp(tmeda)(H)(Cl)]+, [RuCp(tmeda)(N2)]+, and [RuCp(tmeda)(O2)]+. The reactions of [RuCp(tmeda)][BAr′4] with the above gases have also been carried out as solid–gas reactions. Treatment of [RuCp(tmeda)]+ with the terminal acetylenes HCCR (R=But, SiMe3) results in the formation of the vinylidene complexes [RuCp(tmeda)(CCHR)]+. In the case of R=SiMe3 upon treatment with HCl, the parent vinylidene complex [RuCp(tmeda)(CCH2)]+ is formed. [RuCp(tmeda)(η2-HCCH)]+ and [RuCp(tmeda)(CCH2)]+ are not interconvertable for kinetic reasons. Furthermore, [RuCp(tmeda)]+ reacts slowly with both CH2Cl2 and CH2Br2 to give the carbene complex [RuCp(tmeda)(CH2)]+ involving double CX bond activation.