Expanding the family of heterobimetallic Bi-Rh paddlewheel carboxylate complexes via equatorial carboxylate exchange

Five novel homoleptic heterobimetallic bismuth(II)-rhodium(II) carboxylate complexes-BiRh(TPA)(4) (1), BiRh(but)(4) (2), BiRh(piv)(4) (3), BiRh(esp)(2) (4), and BiRh(OAc)(4) (5)-were synthesized in good yields by equatorial ligand substitution starting from BiRh(TFA)(4) (TPA = triphenylacetate, but = butyrate, piv = pivalate, esp = alpha,alpha,alpha',alpha'-tetramethyl-1,3-benzenedipropionate, OAc = acetate, and TFA = trifluoroacetate). We report here H-1 and C-13{H-1} NMR spectra and cyclic voltammograms for complexes 1-4, and IR spectra for all complexes. Irreversible redox waves appear between -1.4 to -1.5 V for [BiRh](3+/4+) couples and 1.3 to 1.5 V vs. Fc/Fc(+) for [BiRh](4+/5+) couples for complexes 1-4 indicating a wide range of stability for the compounds. The X-ray crystal structure of 1 reveals a Bi-Rh distance of 2.53 angstrom.