om6b00929_si_001.pdf (10.35 MB)

Perfluoroalkylation of Coordinated Ethene in Rh(I) and Ir(I) Complexes. Catalytic Addition of Iodoperfluoroalkanes to Ethene

Download (10.35 MB)
journal contribution
posted on 21.03.2017 by María Blaya, Delia Bautista, Juan Gil-Rubio, José Vicente
The complexes [M­(η5-Cp*)­(η2-C2H4)2] (M = Rh, Ir) react with iodoperfluoroalkanes to give [M­(η5-Cp*)­(CH2CH2RF)­(μ-I)]2 (main product) and [M­(η5-Cp*)­(CH2CH2RF)­(μ-I)2M­(η5-Cp*)­I] (RF = t-C4F9, M = Ir; RF = c-C6F11, M = Ir, Rh). Similarly, the complexes [M­(η5-Cp*)­(η2-C2H4)­(PPh3)] react with iodoperfluoroalkanes to give [M­(η5-Cp*)­(CH2CH2RF)­I­(PPh3)] (M = Ir, RF = t-C4F9, i-C3F7; M = Rh, RF = t-C4F9). Evidence for the generation of the heptafluoroisopropyl carbanion in the reaction of [Ir­(η5-Cp*)­(η2-C2H4)­(PPh3)] with I-i-C3F7 was obtained, which suggests that the reaction is initiated by the transfer of two electrons from the Ir­(I) complex to the iodoperfluoroalkane. The iodo-bridged complexes react with PPh3 to give [M­(η5-Cp*)­(CH2CH2RF)­I­(PPh3)] (M = Ir, RF = t-C4F9, c-C6F11; M = Rh, RF = c-C6F11). The complexes [Ir­(η5-Cp*)­(CH2CH2RF)­I­(PPh3)] (RF = c-C6F11, i-C3F7) react with AgOTf to give [Ir­(η5-Cp*)­H­(η2-CH2CHRF)­(PPh3)]­OTf. The analogous reaction of [Ir­(η5-Cp*)­(CH2CH2-t-C4F9)­I­(PPh3)] gives CH3CH2-t-C4F9 and [Ir­(η5-Cp*)­(η2-o-C6H4PPh2)]­OTf, which reacts with PPh3 to give [Ir­(η5-Cp*)­(η2-o-C6H4PPh2)­(PPh3)]­OTf. This cyclometalated complex and its analogue [Ir­(η5-Cp*)­(η2-o-C6H4PPh2)­(P­(p-Tol)3)]­OTf are also prepared by the reaction of [Ir­(η5-Cp*)­(Me)­Cl­(PPh3)] with AgOTf and PPh3 or P­(p-Tol)3. The derivatives [Ir­(η5-Cp*)­(CH2CH2RF)­(PPh3)­L]­OTf (L = CO, RF = c-C6F11, i-C3F7; L = PPh3, RF = i-C3F7) are isolated in the reactions of the Ir hydrido alkene complexes with CO or PPh3. The reactions of [Rh­(η5-Cp*)­(CH2CH2RF)­I­(PR3)] (R = Me, RF = i-C3F7, n-C4F9, t-C4F9; R = Ph, RF = i-C3F7, t-C4F9, c-C6F11) with AgOTf afford unstable triflato complexes that decompose to give CH2CHRF, but in the presence of PR3 the complexes [Rh­(η5-Cp*)­(CH2CH2RF)­(PR3)2]­OTf (R = Ph, RF = i-C3F7, t-C4F9, c-C6F11; R = Me, RF = i-C3F7, t-C4F9) were formed. When R = Ph, these complexes are unstable and decompose quantitatively to give [Rh­(η5-Cp*)­H­(PPh3)2]­OTf and CH2CHRF. Complexes of the type [M­(η5-Cp*)­(η2-C2H4)2] (M = Rh, Ir) and [Rh­(η5-Cp*)­(CH2CH2RF)­I­(L)] are initiators for the radical addition of IRF to ethene.

History

Exports