This paper describes the synthesis and electrochemical reactivity of octanethiolate monolayer-protected Au cluster compounds (MPCs) in which some of the original octanethiolate monolayer has been substituted by place-exchange reactions with 1-(1,3-dithiapropyl)anthracene-9,10-dion The mixed monolayer MPC can contain as many as 25 anthraquinone sites/cluster, which are all electroactive in rapid, successive one-electron reactions. The voltammetric behavior includes mass-transport-controlled charging of the electrical double layers of the Au cores, which are, in effect, diffusing nanoelectrodes. Mediated electrocatalytic reduction of a gem-dinitrocyclohexane by clusters bearing reduced anthraquinone sites yields electrocatalytic currents larger than those generated using freely diffusing anthraquinone radical anion monomer as mediator.