Treatment of [Pd(dppe)CI,], dppe = Ph,PCH,CH2PPh,, with 2 equivalents of a silver(1) salt in the presence of a solvent ligand (solvent) leads to the formation of [Pd(dppe)(solvent),]Y, where Y = CIO, or BF,.In this way stable complexes with solvent = pyridine, O-bonded dimethyl sulphoxide, dimethylformamide, benzonitrile, o-toluonitrile, acetone, or water as well as (solvent) , = 1,6-dicyanohexane or o-phthalonitrile have been isolated and characterised. Complexes with solvent = methanol, ethanol, acetonitrile, or tetrahydrofuran are stable in solution ; on attempted isolation the ethanol complex deposits palladium metal, the methanol and tetrahydrofuran perchlorate complexes yield the bis(perch1orato)-complexes [Pd(dppe) (OC10,)2], and the acetonitrile complex yields mainly [Pd(dppe) (NCMe),] [CIO,], with a small amount of perchlorate-co-ordinated complex. The coordinated perchlorate ligands are readily displaced in solution by any of the solvent ligands; the bis(acetone) complex is very sensitive to moisture yielding [Pd(dppe)(OH,),] [CiO,], on exposure to air. Attempts to displace acetone from [Pd(dppe) (OCMe,),12f and perchlorate from [Pd(dppe)(OCIO,),] by carbon mmoxide failed. The solvent molecules dichloromethane and benzene do not form palladium(ii) complexes of the present type; treatment of [Pd(dppe)CI,] with 2 equivalents of silver(1) perchlorate in dichloromethane-benzene yields [Pd-(dppe) (OCIO,),].Preliminary investigation of the catalytic abilities of these palladium(ii) complexes has shown that [Pd(dppe) (OCMe,),] [C104]z catalyses the hydrogenation of styrene to ethylbenzene at atmospheric pressure and 30 "C, which is remarkably high activity for palladium(ll).
