Palladium(II) Complexes with 1,1'-Bis(diphenylphosphino)ferrocenes [Fe(hapto5-C5R4PPh2)2]n+ (dppf, R= Me, n=0; dppomf, R= Me, n=0; dppomf+, R= Me, n=1). Synthesis, Characterization, and Catalytic Activity in Ethene Methoxycarbonylation

Several palladium(II) complexes with 1,1'-bis(diphenylphosphino)octamethylferrocene (dppomf) and its oxidized form 1, 1'-bis(diphenylphosphino)octamethylferrocenium (dppomf+) have been synthesized and characterized by spectroscopic and electrochemical methods. For comparative purposes, analogous Pd(II) derivatives with dppf have been also prepared. Single crystal X-ray analyses have been carried out for the square-planar mononuclear compounds [Pd(H2O)2(dppf)](OTf)2 and [Pd(H2O)(dppomf)](OTf)2 and for the binuclear complex [Pd( mu-OPF2O)(dppomf+)]2(BF4)4 6CH2Cl2 in which two [Pd-(dppomf+)]3+ moieties are held together by the oxygen atoms of two bridging PO2F2- groups derived from the oxidative degradation of PF6- ions. Selected dppf and dppomf Pd(II) complexes have been employed as catalyst precursors for the methoxycarbonylatiobn of ethene (600 psi, 1:1 CO/C2H4, 85°C). It has been found that dppomf generates selective catalysts for the production of methyl propanoate, while dppf leads to a variety of low-molecular weight oxygenates spanning from methyl propanoate to alternating oligoketones.