New dirhenium(III) compounds bridged by carboxylate ligands: N(C4H9)4[Re2(OOCCF3)Cl6] and Re2(OOCCCHCo2(CO)6)4Cl2

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[Re2(OOCCF3)Cl6] (1) and to the rhenium carbonyl dimer Re2(μ2-Cl)2(CO)8 as the rhenium-reduced byproduct. The reaction of the precursor complex, N(C4H9)4[Re2(OOCCF3)Cl6] (1), with the organometallic carboxylic acid (CO)6Co2HCCCOOH leads to the cluster of clusters compound Re2(OOCCCHCo2(CO)6)4Cl2 (2), which has the dimer structure of Re2(OOCR)4Cl2. Cyclic voltammetric measurements show that Re2(OOCCCHCo2(CO)6)4Cl2 (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 Re2(OOCCCHCo2(CO)6)4Cl2 (2) compared to the parent ligand (CO)6Co2HCCCOOH and rhenium pivalate.