文摘
Cyclic voltammetry of 31 icosahedral carborane anions 1-X-12-Y-CB11Me10鈥?/sup> at a Pt electrode in liquid SO2 revealed a completely reversible one-electron oxidation even at low scan rates, except for the anions with Y = I, which are oxidized irreversibly up to a scan rate of 5.0 V/s, and the anion with X = COOH and Y = H, whose oxidation is irreversible at scan rates below 1.0 V/s. Relative reversible oxidation potentials agree well with RI-B3LYP/TZVPP,COSMO and significantly less well with RI-BP86/TZVPP,COSMO or RI-HF/TZVPP,COSMO calculated adiabatic electron detachment energies. Correlations with HOMO energies of the anions are nearly as good, even though the oxidized forms are subject to considerable Jahn鈥揟eller distortion. Except for the anion with X = F and Y = Me, the oxidation potentials vary linearly with substituent 蟽p Hammett constants. The slopes (reaction constants) are 0.31 and 0.55 V for positions 1 and 12, respectively.