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

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 H-1-, P-31-, C-13-NMR spectroscopy, kelemental analysis, and UV-vis spectroscopy. (C) 2001 Elsevier Science B.V. All rights reserved.