Palladium(II) complexes containing symmetrical diphosphine ligands based on ferrocene. Sterically enforced palladiumiron bonds

Abstract Methylpalladium chloride, cationic methyl- and acylpalladium triflate complexes were synthesised containing bis(dialkyl) and bis(diphenyl)phosphine ferrocene ligands. Trans -coordinated cationic methylpalladium complexes containing 1,1′-bis(di- tert -butylphosphino)ferrocene, form a palladiumiron bond. The less bulky 1,1′-bis(di- iso -propylphosphino)ferrocene ligand coordinates in a cis fashion in methylpalladium chloride complexes. A palladiumiron bond was indicated in the cationic acylpalladium complexes of both alkylphosphine ligands. 1,1′-Bis(diphenylphosphino)ferrocene does not form a palladiumiron bond in the monocationic acyl- and methylpalladium complexes. The complexes were characterised by 1 H-, 31 P-, 13 C-NMR spectroscopy, elemental analysis, and UV–vis spectroscopy.