PROTON-TRANSFER FROM A FULLERENE DICATION - BRACKETING THE GAS-PHASE ACIDITY OF C(60)H.2+

Several gas-phase ion-molecule reactions of the hydrogenated fullerene dication C60H.2+ (produced by the reaction of C60(.3+) + C3H8) have been studied using a SIFT apparatus at 0.35 +/- 0.01 Torr and 294 +/- 2 K. Proton transfer from C60H.2+ to the neutrals CH2CHCN, CH3OH, CH3NO2, HCOOH, CH2(CN)2, H2CO, and HCN has been observed but was not detected in reactions of C60H.2+ with several other neutrals. The occurrence of efficient proton transfer to neutrals having a gas-phase basicity (GB) value > 170 kcal mol-1 and failure to proton transfer with neutrals having GB < 163 kcal mol-1 is used to bracket the gas-phase acidity of GA(C60H.2+) = 124 +/- 8 kcal mol-1, when consideration is taken of the effects of Coulombic repulsion between the product ions. The reactivity of C60H.2+ is compared to that of C-60(2+) and thermochemical data are derived for DELTAH(f)degrees(C60H.2+), IE(C60H+), the hydrogen-atom affinity of C-60(2+), and the hydride affinity of C-60(.3+).