Pure and Applied Chemistry

Abstract: Buckminsterfullerene, C₆₀, is readily reduced on exposure to solutions of strongly reducing transition-metal carbonylate anions to give the radical anion fulleride C₆₀^- and the corresponding highly reactive, 17-electron neutral compounds. Three secondary reaction paths have been identified, depending on the nature of the reactants and the reaction conditions. (1) With Na⁺ and PPN⁺ salts of [Mn (CO) ₅]^-, thermal substitution of a CO on the metal radical by the C60-results in formation of the anionic, h²-fullerene complex [Mn (C₆₀) (CO) ₄]^- . (2) With salts of [Co (CO) ₄]^-, the thermal reaction results in formation of a novel transition-metal fulleride NaCoC₆₀ while (3) with Na[CpFe (CO) ₂] and [CpM (CO) ₃]^- (M = Mo, W) , the 17-electron intermediates couple to form the 18-electron dimers, [CpFe (CO) ₂]₂ and [CpM (CO) ₃]₂. In contrast, photochemical reactions of C₆₀ with salts of [Mn (CO) ₅]^-, [Co (CO) ₄]^-, and [CpM (CO) ₃]^- result in excellent yields of the complexes [Mn (C₆₀) (CO) ₄]^- , [Co (C₆₀) (CO) ₃]^- and [CpM (C₆₀) (CO) ₂]^- , respectively; analogous complexes of C₇₀ may be made similarly. The new complexes have been characterized crystallographically, by IR, ¹³C NMR, and/or Raman spectroscopy and by electrospray mass spectrometry.