o-Diarylphosphinoferrocene Sulfonate Palladium Systems for Nonalternating Ethene–Carbon Monoxide Copolymerization

A series of ferrocene-derived o -diarylphosphino/sulfonate ligands were prepared. Treatment of the o -diphenylphosphinoferrocene sulfonic acid ( 2a ) with (allyl)PdCl dimer and sodium carbonate as the base gave the corresponding chelate (Fc-O,P)Pd(π-allyl) complex 7a (as a mixture of two isomers). In the presence of pyridine instead of Na 2 CO 3 the analogous reaction yielded the square-planar (Fc-O,P)Pd(Cl)pyridine complex 8a . Both systems were characterized by X-ray diffraction. Reaction of the series of three differently −P(aryl) 2 -substituted (Fc-O,P)H ligands with PdMe 2 (tmeda) gave the respective (Fc-O,P)PdMe(pyridine) derivatives ( 11 ). All three examples 11a, b, c and one precursor complex, [(Fc-O,P)PdMe] 2 (tmeda) ( 10a ), were characterized by X-ray diffraction. The ligand system o -bis( o -anisyl)phosphinoferrocene sulfonic acid ( 2b ) formed an active catalyst for ethene/CO nonalternating copolymerization upon treatment with Pd(OAc) 2 in methanol. Up to ca. 25% extra ethene incorporation was obtained at an ethene/CO partial pressure ratio of ca. 10:1. This catalyst system and its equivalent derived from the preformed (Fc-O,P)PdMe(pyridine) precursor complex ( 11b ) showed reasonable catalyst activities under these conditions.