Pentafluorophenyl imidato palladium(ii) complexes: catalysts for Suzuki cross-coupling reactions

Abstract

Novel N-bonded imidato complexes of general formula [Pd(N–N)(C₆F₅)(imidate)] (imidate = maleimidate, succinimidate or phthalimidate; N–N = 2,2′-bipyridine (bipy), 4,4′-dimethyl-2,2′-bipyridine (Me₂bipy) or N,N,N′,N′-tetramethylethylenediamine (tmeda)), [NBu₄][Pd(C₆F₅)(H₂O)(succinimidate)₂] and [NBu₄][Pd(C₆F₅)(L)(succinimidate)₂] (L = PPh₃ or t-BuNC) have been synthesised. These complexes are air-, light- and moisture-stable. The crystal structures of [Pd(tmeda)(C₆F₅)(maleimidate)]·H₂O·0.5CHCl₃, [NBu₄][Pd(C₆F₅)(H₂O)(succinimidate)₂]·H₂O and [NBu₄][Pd(C₆F₅)(t-BuNC)(succinimidate)₂]·2H₂O have been determined by X-ray diffraction. Many of these new complexes are shown to be active phosphine-free palladium catalysts/precatalysts for the Suzuki cross-coupling reactions of aryl bromides and aryl chlorides with phenylboronic acid.