The solvothermal reaction of (N(C4H9)(4))(2)[Re2Cl8] with trifluoroacetic acid and acetic anhydride leads to the new rhenium trifluoroacetate dimer N(C4H9)(4)[Re-2(OOCCF3)Cl-6] (1) and to the rhenium carbonyl dimer Re-2(mu(2)-Cl)(2)(CO)(8) as the rhenium-reduced byproduct. The reaction of the precursor complex, N(C4H9)(4)[Re-2(OOCCF3)Cl-6] (1), with the organometallic carboxylic acid (CO)(6)CO2HCCCOOH leads to the cluster of clusters compound Re-2(OOCCCHCo2(CO)(6))(4)-Cl-2 (2), which has the dimer structure of Re-2(OOCR)(4)Cl-2. Cyclic voltammetric measurements show that Re-2(OOCCCHCo2(CO)(6))(4)Cl-2 (2) has one reduction centered on the dirhenium core and a reduction centered on the cobalt atoms. DFT calculations have been used to rationalize the observed displacements of the voltammetric signals in Re-2(OOCCCHCo2(CO)(6))(4)Cl-2 (2) compared to the parent ligand (CO)(6)Co2HCCCOOH and rhenium pivalate.