New methods for the synthesis transition-metal fullerene complexes

Buckminsterfullerene, C-60, is readily reduced on exposure to solutions of strongly reducing transition-metal carbonylate anions to give the radical a nion fulleride C-60(-) and the corresponding highly reactive, 17-electron n eutral compounds. Three secondary reaction paths have been identified, depe nding 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 m etal radical by the C-60(-) results in formation of the anionic, eta (2)-fu llerene complex [Mn(C-60)(CO)(4)](-). (2) With salts of [Co(CO)(4)](-), the thermal reaction results in formation of a never transition-metal fullerid e NaCoC60 while (3) with Na[CpFe(CO)(2)] and [CpM(CO)(3)](-) (M = Mo, W), t he 17-electron intermediates couple to form the 18-electron dimers, [CpFe(C O)(2)](2) and [CpM(CO)(3)](2). In contrast, photochemical reactions of C60 with salts of [Mn(CO)(5)](-), [Co(CO)(4)](-), anal [CpM(CO)(3)](-) result i n excellent yields of the complexes [Mn(C-60)(CO)(4)](-), [Co(C-60)(CO)(3)] (-) and [CpM(C-60)(CO)(2)](-), respectively; analogous complexes of C-70 ma y be made similarly. The new complexes have been characterized crystallogra phically, by IR, C-13 NMR, and/or Raman spectroscopy and by electrospray ma ss spectrometry.