Single Electron Delivery to Lewis Pairs: An Avenue to Anions by Small Molecule Activation.

Single electron transfer (SET) reactions are effected by the combination of a Lewis acid (e.g., E(C6 F5 )3 E = B or Al) with a small molecule substrate and decamethylferrocene (Cp*2 Fe). Initially, the corresponding reactions of (PhS)2 and (PhTe)2 were shown to give the species [Cp*2 Fe][PhSB(C6 F5 )3 ] 1 and [Cp*2 Fe][(μ-PhS)(Al(C6 F5 )3 )2 ] 2 and [Cp*2 Fe][(μ-PhTe)(Al(C6 F5 )3 )2 ] 3, respectively. Analogous reactions with di-tert-butyl peroxide yielded [Cp*2 Fe][(μ-HO)(B(C6 F5 )3 )2 ] 4 with isobutene while with benzoyl peroxide afforded [Cp*2 Fe][PhC(O)OE(C6 F5 )3 ] (E = B 5, Al 6). Evidence for a radical pathway was provided by the reaction of Ph3 SnH and p-quinone afforded [Cp*2 Fe][HB(C6 F5 )3 ] 7 and [Cp*2 Fe]2 [(μ-O2 C6 H4 )(E(C6 F5 )3 )2 ] (E = B 8, Al 9). In addition, the reaction of TEMPO with Lewis acid and Cp*2 Fe afforded [Cp*2 Fe][(C5 H6 Me4 NOE(C6 F5 )3 ] (E = B 10, Al 11). Finally, reactions with O2 , Se, Te and S8 gave [Cp*2 Fe]2 [((C6 F5 )2 Al(μ-O)Al(C6 F5 )3 )2 ]2 12, [Cp*2 Fe]2 [((C6 F5 )2 Al(μ-Se)Al(C6 F5 )3 )2 ]2 13, [Cp*2 Fe][(μ-Te)2 (Al(C6 F5 )2 )3 ] 14 and [Cp*2 Fe]2 [(μ-S7 )B(C6 F5 )3 )2 ] 15, respectively. The mechanisms of these SET reactions are discussed, and the ramifications are considered.