Gas-phase reactions of singly and multiply-charged fullerene cations, C60x+ (x=1-3), with iron pentacarbonyl:: kinetic control by Coulombic barriers

Selected-ion flow tube measurements of rate coefficients and product distributions are reported for the reactions of C-60(+) C-60(2+) and C-60(. 3+) with iron pentacarbonyl in helium buffer gas at 0.35 +/- 0.01 torr and 294 +/- 3 K. A fast bimolecular reaction is observed with C-60(+) leading to a stable derivatized C-60 cation, C60Fe(CO)(4)(+), but the chemistry switches for the higher charge states to charge separation by dissociative-electron transfer leading to the elimination of one and two molecules of CO with C-60(2+) and C-60(. 3+) respectively. The specificity of these CO eliminations is rationalized in terms of favourable entropy changes and kinetic control by energy barriers arising from Coulombic repulsion between product ions. (C) 1997 Elsevier Science B.V.