Systematic method for the incorporation of the {(eta(6)-arene)Fe} fragment into carborane cages via [(eta(6)-arene)Fe]2+ dications. A series of [3-(eta(6)-arene)-closo-3,1,2-FeC2B9H11] complexes. Reliable synthesis of polymethylated [(eta(6)-arene)2Fe]2+ cations.