Thioether Iron Complexes [(X‐SMe‐7,8‐C2B9H10)Fe(C6H6)] (X = 9 or 10) as Synthons of Neutral Ferracarborane Fragments

Demethylation of cyclohexadienyl complexes (η-X-SMe2-7,8-C2B9H10)Fe(η5-C6H7) (1a,b; X = 9 (a), 10 (b), where X is number of the substituent position) with PhCH2SNa in DMF (dimethylformamide) and subsequent protonation by acetic acid lead to iron benzene complexes (η-X-SMe-7,8-C2B9H10)Fe(η-C6H6) (2a,b). Visible light irradiation of 2a in the presence of tBuNC or Cp*Fe(η-cyclo-P5) affords neutral half-sandwich (η-9-SMe-7,8-C2B9H10)Fe(tBuNC)3 (3) or triple-decker (η-9-SMe-7,8-C2B9H10)Fe(μ-η:η-cyclo-P5)FeCp* (4) complexes. Reaction of 2b with (THF)W(CO)5 selectively gives the iron-tungsten dinuclear complex (η-10-SMe(W(CO)5)-7,8-C2B9H10)Fe(η-C6H6) (5). Structures of 2a, 4 and 5 were determined by X-ray diffraction. Electrochemistry reveals that the redox processes of the SMe-substituted ferracarboranes are cathodically shifted (by 350 mV) with respect to the corresponding redox changes of the SMe2-analogs. The Fe-C6H6 bonding in 2a and the related benzene complexes [(η-9-SMe2-7,8-C2B9H10)Fe(η-C6H6)]+ and (η-7,8-C2B9H10)Fe(η-C6H6) was analyzed by energy decomposition analysis.