Trimethyl-palladium(IV) and -platinum(IV) complexes containing phosphine donor ligands, including studies of 1,5,9-triethyl-1,5,9-triphosphacyclodecane and X-ray structural studies of palladium(II) and palladium(IV) complexes

Abstract

Dimethyl(2,2'-bipyridine)palladium(II) reacted with methyl triflate (CF3SO3Me) at -60 C to form a palladium(IV) complex which reacted with a range of monodentate phosphines [PPh3, PMePh2, PMe2Ph, PCy3, P(OMe)3], 1,2-bis(diethylphosphino)ethane (depe), or syn,syn-1,5,9-triethyl-1,5,9-triphosphacyclodecane (syn,syn-Et3[12]aneP3) to form complexes containing octahedral palladium(IV) centres fac-[PdMe3(2,2'-bipy)(L)]+ (1–5, 11–13). The ligand depe bridges between palladium(IV) centres in a binuclear complex (11), the triphosphine forms both mononuclear (13) and binuclear species (12), and representative complexes of other bidentate nitrogen donor ligands have also been prepared, [PdMe3(N–N)(PMe2Ph)][O3SCF3] [N–N = 1,10-phenanthroline (phen) 6 or N,N,N',N'-tetramethylethylenediamine (tmen) (7)]. The first structural analysis of an organopalladium(IV) phosphine complex is reported, and octahedral (6) and platinum(IV) complexes [PtMe3(2,2'-bipy)(L)][O3SCF3] [L = PPh3 (8), PMePh2 (9) or PMe2Ph (1] have been isolated. All of the palladium() complexes reductively eliminate ethane on decomposition to form palladium(II) species, where the monodentate phosphines form [PdMe(N–N)(L)]+ (1a–7a); a structural analysis of square-planar [PdMe(2,2'-bipy)(PMe2Ph)][O3SCF3] (3a) is reported. The stability of palladium(IV) complexes decreases in the order PMe2Ph > PMePh2 > PPh3, and for complexes of PMe2Ph there is a stability order phen > 2,2'-bipy > tmen for [PdMe3(bidentate ligand)(PMe2Ph)]+.