Proton transfer from a fullerene dication: bracketing the gas-phase acidity of C60H.bul.2+

Abstract

Several gas-phase ion-molecule reactions of the hydrogenated fullerene dication C[sub 60]H[sup [center dot]2+] (produced by the reaction of C[sub 60][sup [center dot]3+] + C[sub 3]H[sub 8]) have been studied using a SIFT apparatus at 0.35 [+-] 0.01 Torr and 294 [+-] 2 K. Proton transfer from C[sub 60]H[sup [center dot]2+] to the neutrals CH[sub 2]CHCN, CH[sub 3]OH, CH[sub 3]NO[sub 2], HCOOH, CH[sub 2](CN)[sub 2], H[sub 2]CO, and HCN has been observed but was not detected in reactions of C[sub 60]H[sup [center dot]2+] with several other neutrals. The occurrence of efficient proton transfer to neutrals having a gas-phase basicity (GB) value > 170 kcal mol[sup [minus]1] and failure to proton transfer with neutrals having GB < 163 kcal mol[sup [minus]1] is used to bracket the gas-phase acidity of GA(C[sub 60]H[sup [center dot]2+]) = 124 [+-] 8 kcal mol[sup [minus]1], when consideration is taken of the effects of Coulombic repulsion between the product ions. The reactivity of C[sub 60]H[sup [center dot]2+] is compared to that of C[sub 60][sup 2[center dot]] and thermochemical data are derived for [delta]H[degrees][sub f] (C[sub 60]H[sup [center dot]2+]), IE(C[sub 60]H[sup +]), the hydrogen-atom affinity of C[sub 60][sup 2+], and the hydride affinity of C[sub 60][sup [center dot]3+]. 47more » refs., 2 figs., 1 tab.« less