From the reactions between Mo-2((O2CBu)-Bu-t)(4) and each of terephthalic acid and 4,4'-azodibenzoic acid, the compounds [Mo-2((O2CBu)-Bu-t)(3)](2)(mu-O2CC6H4CO2) (1) and [Mo-2((O2CBu)-Bu-t)(3)](2)(mu-O2CC6H4N2C6H4CO2) (2) have been made and characterized by spectroscopic and electrochemical methods. Their electronic structures have been examined by computations employing density functional theory on model compounds where HCO2 substitutes for (BuCO2)-Bu-t. On the basis of these studies, the two Mo2 units are shown to be only weakly coupled and the mixed-valence ions 1(+) and 2(+) to be valence-trapped and Class II and I, respectively, on the Robin-Day classification scheme for mixed-valence compounds. These results are compared to t(2g)(6)-Ru centers linked by 1,4-dicyanamidobenzene and azo-4,4'-diphenylcyanamido bridges for which the mixed-valence ions [Ru-bridge-Ru](5+) have been previously classified as fully delocalized, Class III [Crutchley et al. Inorg. Chem. 2001, 40, 1189; Inorg. Chem. 2004, 43, 1770], and on the basis of results described herein, it is proposed that the latter complex ion is more likely a mixed-valence organic radical where the bridge is oxidized and not the Ru(2+) centers.