Piano-stool (pentamethylcyclopentadienyl)iron complexes: Syntheses and simple coordination chemistry

Article abstract of DOI:10.1021/om00085a022

(Fp′CO)⁺PF₆^-, 3e [Fp′ = (η⁵-C₅Me₅)Fe(CO)₂], is synthesized by reaction of Fp′Br with CO (40 atm) and AlCl₃ or by reaction of Fp′₂ with Cp₂Fe⁺PF₆^- in THF under CO (1 atm). Oxidation of Fp′₂ with Cp₂Fe⁺PF₆^- in various coordinating solvents S (THF, acetone, acetonitrile, pyridine) gives (Fp′S)⁺PF₆^- (3a-d) in high yields. Reaction of (Fp′THF)⁺PF₆^-, 3a, with various ligands L (PPh₃, P(OPh)₃, CO) gives (Fp′L)⁺PF₆^-, 3e-g, in high yields; the reaction fails with olefins. 3a also gives Fp′H, 5, with NaBH₄ and Fp′SC(S)NMe₂, 6a, with NaS₂CNMe₂, but 6a is obtained in better yield from 3e. Bimetallic complexes [FpSC(NEt₂)-S→Fp′]⁺PF₆^-, 6c, and [CpFe(η⁶-C₆Me₅CH ₂)Fp′]⁺PF₆^-, 7, are also obtained by reaction of 3a with FpSC-(S)NEt₂ and Cp(η⁵-C₆Me₅CH₂)Fe, respectively. Photolysis of 3e or (Fp′NCMe)⁺PF₆^-, 3c, in CH₃CN gives a 80% yield of the thermally stable, air-sensitive complex [Cp′Fe(NCMe)₃]⁺PF₆^-, 9, as deep purple crystals. Without degassing, this photolytic reaction gives dark red [Cp′Fe(NCMe)₂(CO)]⁺PF₆^-, 10, also obtained from 9 under 1 atm of CO at 20°C. 9 also reacts with PPh₃ to give [Cp′Fe(NCMe)₂(PPh₃)]⁺PF₆ ^-, 11, with dppe to give [Cp′Fe(NCMe)(η²-dppe)]⁺PF₆ ^-, 12, and with cyclooctatetraene (COT) to give [Cp′Fe(η⁶-COT)]⁺PF₆^-, 13. The reaction of CO with 11 and 12 gives respectively [Cp′Fe(CO)₂(PPh₃)]⁺PF₆ ^-, 3f, also obtained from 3e and PPh₃ in refluxing acetone, and [Cp′Fe(CO)(η²-dppe)]⁺PF₆^-, 15. Fp′^-K⁺, 16a, obtained from Fp′₂ and K mirror, gives Fp′CH₃, 17, upon alkylation with CH₃I and Fe′^-Na⁺, 16b, obtained from Fp′₂ and Na/Hg, gives Fp′CH₂OCH₃, 18, upon alkylation with ClCH₂OCH₃.