Additive tuning redox potential in metallacarboranes by sequencial halogen substitution

Abstract

The first artificially made set of electron acceptors is presented that are derived from a unique platform Cs[3,3′-Co(C2B9H11)2], for which the redox potential of each differs from its predecessor by a fixed amount. The sequence of electron acceptors is made by substituting one, two, or more hydrogen atoms by chlorine atoms, yielding Cs[3,3′-Co(C2B9H11−yCly)(C2B9H11−zClz)]. The higher the number of chlorine substituents, the more prone the platform is to be reduced. The effect is completely additive, so if a single substitution implies a reduction of 0.1 V of the redox potential of the parent complex, then ten substitutions imply a reduction of 1 V.