Styrene derivatives of the manganese tricabonyl cation have been synthesized through the reaction of Mn(CO)(5)BF4 with excess styrene derivatives in refluxing CH2Cl2, and their chemical reduction has been studied. Treatment of [(styrene)Mn(CO)(3)](+) (1(H)) with 1.0 equiv of Cp2Co in CH2Cl2 or THF led to isolation of bimetallic 2(H). Treatment of [(1,1-diphenylethylene)Mn(CO)(3)](+) (1(Ph)) with 1.0 equiv of Cp2Co in CH2Cl2 yielded three different bimetallic compounds, 2(Ph), 3(Ph), and 4(Ph). The molecular structures of 2(H), 2(Ph), 3(Ph), and 4(Ph), determined by X-ray crystallography, were quite different from those of known bimetallics. Compounds 2(H) and 2(Ph) have the eta(5):eta(3) bonding pattern, where a Mn(CO)(4) moiety is coordinated to the styrene in an eta(3)-fashion. Compound 3(Ph) has the eta(5):eta(5) bonding pattern with two Mn(CO)(3) moieties pi-coordinated to a ligand derived from a coupling of 1,1-diphenylethylenes through the ipso carbon atom. Compound 4(Ph) has a metal-metal bond with no bridging carbonyls; one of the manganese atoms is coordinated by 1,1-diphenylethylene and two carbonyls and the other by the Mn(CO)(5). There are multiple reduction pathways available to (arene)Mn(CO)(3)(+) cations having a vinyl substituent on the arene ring.