CONVENIENT METHOD FOR THE SYNTHESIS OF CHLORO-BRIDGED METHYLPALLADIUM AND ACETYLPALLADIUM(II) DIMERS

A series of chloro-bridged methylpalladium(II) dimers of the type [Pd2(mu-Cl)2Me2L2] (la-h; L = PEt3, PMePh2, PPh3, P(CH2Ph)3, P(OMe)3, AsPh3, CNBu(t), 2,6-lutidine) has been prepared from [PdClMe(cod)] and 1 equiv of the appropriate ligand. Cis and trans isomers may be identified where L = PEt3 or CNBu(t). Addition of a second equivalent of PEt3 results in a bridge-splitting reaction to give trans-[PdClMe(PEt3)2] (2a), but this process may be reversed by addition of further [PdClMe(cod)]. Carbonylation of [PdClMe(cod)] yields the corresponding acetyl complex, and treatment of the latter with PEt3, AsPh3, or CNBu(t) leads to the acetylpalladium dimers [Pd2(mu-Cl)2(COMe)2L2] (3a,f,g). Reaction of 3a with PEt3 produces trans-[PdCl(COMe)(PEt3)2] (4a), but this may also be reversed by addition of further [PdCl(COMe)(cod)]. Addition of excess CNBu(t) to [PdClMe(cod)] generates the iminoacyl complex trans-[PdCl{C(=NBu(t))Me}(CNBu(t))2] (6g).