Synthesis and reactions of new organothallium(I) compounds derived from the reactions of cyclopentadienylthallium(I) with electrophilic olefins

Article abstract of DOI:10.1021/ic50207a005

The reactions of cyclopentadienylthallium (TlCp) with several electrophilic olefins were investigated Reaction of TlCp with tetracyanoethylene yields (tricyanovinyl)cyclopentadienide, Tl⁺[C₅H₄C(CN)C(CN)₂]^- (I), in 90% yield. Similarly the reaction of TlCp with 1,1-dicyano-2,2-bis(trifluoromethyl)ethylene yields Tl⁺[C₅H₄C(CF₃) ₂CH(CN)₂]^- (III). Protonation of I and III with anhydrous HCl results in the formation of the tricyanovinylcyclopentadiene, C₁₀H₅N₃, and both the linear and cross-conjugated isomers of 1,1-dicyano-2,2-bis(trifluoromethyl)-2-cyclopentadienylethane, C₁₁H₆N₂F₆, respectively Compound I was found useful as a general reagent for production of tricyanovinyl-substituted metallocenes, including [η⁵-C₅H₄(CN)C(CN)₂]Mn(CO) ₃, [η⁵-C₅H₄C(CN)C(CN)₂]CuP(C ₆H₅)₃, and [η⁵-C₅H₄C(CN)C(CN) ₂]Fe(η-C₅H₅). It has also been found that [η⁵-C₅H₄C(CN)C(CN) ₂]Fe(η-C₅H₅) can be reacted with TlCp followed by addition of either (η-C₅H₅)Fe(CO)₂I or Mn(CO)₅Br to yield [(η⁵-C₅H₄)Fe(η-C₅H ₅)]₂C₂(CN)₂ and [(η⁵-C₅H₄)Fe(η-C₅H ₅)]C₂(CN)₂[(η⁵-C ₅H₄)Mn(CO)₃], respectively. These latter two compounds are unusual examples of bridged metallocenes containing strongly electron-withdrawing groups on the bridging unit. The reaction of III with (η-C₅H₅)Fe(CO)₂I was also investigated and found to yield [(η⁵-C₅H₄C(CF₃) ₂CH(CN)₂]Fe(η-C₅H₅).