Direct Observation of b-Aryl Eliminations from Rh(I) Alkoxides

β-Aryl eliminations from a series of rhodium(I) alkoxides to form rhodium aryl complexes and free ketones are reported. Tertiary phenylmethoxide complexes [Rh(PEt₃)_n(OCPhRR‘)] (n = 2, 3) were prepared via alcoholysis of {Rh(PEt₃)₂[N(SiMe₃)₂} by the corresponding alcohols HOCPhRR‘ in the presence and absence of added PEt₃. Heating of these complexes in the presence of added PEt₃ generated the rhodium phenyl complex, (PEt₃)₃RhPh, and the corresponding ketones in good to high yields. Kinetic results are most consistent with irreversible β-phenyl elimination from a bisphosphine-ligated rhodium alkoxide complex. Such bisphosphine complexes result from ligand dissociation from the trisphosphine complexes and have been isolated in some cases. The bisphosphine complexes are stabilized by Rh−C_phenyl interactions, as evidenced by an X-ray structure, and this structure with a metal−aryl interaction likely illustrates the pathway for C−C bond cleavage. Read more on publisher's site.