The behavior of rhenium(III) binuclear complexes K(2)Re(2)Hlg(8) and Re-2(RCOO)(2)Hlg(4) [Hlg = Cl and Br; R = CH3, C2H5, (CH3)(2)CH, and (CH3)(3)C] in acetone solutions was studied by H-1 NMR. Reaction with neutral donor ligand (H2O and hexamethylphosphoramide) induces transformation of trans-Re-2(RCOO)(2)Hal(4) to solvated cis-Re-2(RCOO)(2)Hal(4).