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

Abstract

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 = α,α,α′,α′-tetramethyl-1,3-benzenedipropionate, OAc = acetate, and TFA = trifluoroacetate). We report here ¹H and ¹³C{¹H} 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 Å.