Structure, properties, and electrochemical behavior of some binuclear rhodium complexes containing isocyanide, carbon monoxide, and halide ligands

Binuclear rhodium complexes containing isocyanide, carbon monoxide, halide, and the bridging ligands DPM, DAM, and DADPM (DPM = bis(diphenylphosphino)methane; DAM = bis(diphenylarsino)methane; DADPM = (diphenylarsino)(diphenylphosphino)methane) have been investigated. Some aspects of the photolytic and the electrochemical behavior of [Rh₂(RNC)₄(DPM)₂]X₂ (R = CH₃, i-C₃H₇, nC₄H₉, t-C₄H₉; X = PF₆^-; BF₄^-) in coordinating and non-coordinating media are discussed. These compounds are capable of generating dihydrogen in aqueous acetone and are rapidly oxidized in solution in the presence of light at 520 nm. Electrochemical oxidation in the presence of coordinating species produces [Rh₂(RNC)₄Y₂(DPM)₂]X₂ (Y = CN^-, SCN^-, I^-, substituted pyridine). The structure and electrochemistry of Rh₂(CO)₂(DADPM)₂ is also investigated. The reactivities and stabilities of Rh2(CO)2(DADPM)2 have also been investigated. The reactivities and stqabilities of Rh₂(CO)₂Cl₂(DADPM)₂ and its derivatives have been compared with the anlogous DPM and DAM compounds. The new DADPM complexes are characterized by infreared, ultraviolet-visible, and 31_p and 13_C NMR techniques.