FORMATION OF BUCKMINSTERFULLERENE PHENYLENE DERIVATIVES IN THE GAS-PHASE

The gas-phase chemistry of Fe(C6H4)(n)(+) (n = 1-6) with C-60 is studi ed by using Fourier transform ion cyclotron resonance mass spectrometr y. The formation of some ionic phenylene derivatives and metallacyclic derivatives of C-60 is observed. Specifically, Fe+, generated by lase r desorption, reacts with chlorobenzene to form iron-benzyne, FeC6H4+, which initiates further reactions with chlorobenzene to form Fe(C6H4) (2-6)(+) and (C6H4)(2-5)(+). Fe(C6H4)(1-4)(+) react with C-60 to form metalated fullerene derivatives, C60Fe(C6H4)(1-4)(+). C60Fe(C6H4)(1,2) (+) undergo a demetalation reaction with chlorobenzene to yield the fu llerene phenylene derivatives C-60(C6H4)(1,2)(+), 8 and 9, through for mation of C-C bonds with C-60. CID experiments and kinetic analysis in dicate that each of the C60Fe(C6H4)(1,2)(+) species consists of a sing le isomer, presumably the metallacycles 12 and 14. Consistent with the typical reactions of metal-benzyne complexes with alkenes in the cond ensed phase, these metallacyclic structures are believed to be formed through coupling of one of the double bonds at the 6,6 ring junction i n C-60 with an Fe-C sigma bond of Fe(benzyne)(+). These results are co nsistent with the notion that C-60 acts like an electron deficient alk ene rather than an aromatic molecule, and suggest a possible synthetic route to prepare this type of metallo-C-60 derivatives in the condens ed phase. Finally, ligand displacement reactions yield a bond dissocia tion energy of D-o(Fe+-C-60) = 44 +/- 7 kcal/mol.