An electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry study of 1,6-methano[60]fullerene-61,61-dicarboxylic acid

1,6-Methano[60]fullerene-61,61-dicarboxylic acid was studied by electrospra y ionization Fourier transform ion cyclotron resonance mass spectrometry, T he deprotonated molecule, C60C(COOH)COO-, and the decarboxylated molecular anion C60CHCOO- were observed. Gas-phase ion-molecule reactions occurred wh en the ion accumulation time in an external rf/dc hexapole ion trap was ext ended. Cluster ions of the type [C60CHCOOH](n)[C60CHCOO](-) (n = 1-2) were observed. Multiply-charged anions were observed for the dimer [C60CHCOOH][C 60CHCOO](-). Collision-induced dissociation in the ion cyclotron resonance cell showed that C60C(COOH)COO- dissociated through the loss of two CO2 gro ups, with further fragmentation to produce C-60(-). A similar fragmentation pathway was also observed with capillary/skimmer collision-induced dissoci ation during the electrospray process. Semi-empirical calculations using th e AM1 approximation with the MOPAC program have been performed on most of t he neutral and ionic species related to this compound. Energy differences a nd charge distributions have been obtained for the possible geometry struct ures for these species.