Addition of cyclopropenylium and tropylium ions to cyclooctatetraene-cobalt and -rhodium cyclopentadienyl complexes

Abstract

Cyclopropenylium ions [C₃R′₃]⁺(R′= Ph or Bu^t) react with [Co(η⁴-cot)(η-C₅R₅)](R = H or Me, cot = cyclooctatetraene) to give [M{η⁵-C₈H₈(C₃R′₃)}(η-C₅R₅)]⁺3(M = Co; R = H, R′= Ph; R = Me, R′= Ph or Bu^t); X-ray structural studies on 3(M = Co, R = H, R′= Ph) show an exo-cyclopropene substituent on the cyclooctatrienyl ring. The reaction of [C₃Ph₃]⁺ with [Rh(η⁴-cot)(η-C₅Me₅)] gives a similar product 3(M = Rh, R = Me, R′= Ph) which rearranges to an unknown isomer 5 whereas [Rh(η⁴-cot)(η-C₅H₅)] undergoes electrophilic substitution at the cyclopentadienyl ring to give [Rh(η²,η³-C₈H₉){η-C₅H₄(C₃Ph₃)}]⁺4. The addition of [C₇H₇]⁺ to [Co(η⁴-cot)(η-C₅R₅)](R = H or Me) gives [Co{η⁵-C₈H₈(C₇H₇)}(η-C₅R₅)]⁺6(R = H or Me) which, in the case of 6(R = Me), rearranges to the 1,2,3,3a-tetrahydropentalenyl complex [Co{η⁵-C₈H₈(C₇H₇)}(η-C₅Me₅)]⁺7. Finally, the reactions between [Rh(η⁴-cot)(η-C₅R₅)](R = H or Me) and [C₇H₇]⁺ give [Rh(η²,η³-C₈H₉){η-C₅H₄(C₇H₇)}]⁺8 and [Rh{η²,η³-C₈H₈(C₇H₇)}(η-C₅Me₅)]⁺9 respectively.