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The reaction of the complexes [FeCpX(CO)2] (X = Cl, Br, I) into either [FeCp(CO)(PP)]X or [FeCpX(PP)] (PP = a bidentate diphosphine ligand) is shown to be highly dependent of the phosphine ligand used. Diphosphine ligands that form stable chelates favor formation of the neutral complex, whereas diphosphine ligands that form less stable chelates favor formation of the cationic complex. Thus, with the use of dppdmp (= 1,3-bis(diphenylphosphino)-2,2-dimethylpropane) the [FeCpX(PP)] complexes (X = Cl, Br, I) are selectively formed, induced by a gem-dialkyl effect. Apart from the bidentate phosphine ligand, the halide ion present in the iron complex has a significant influence on the course of the substitution reaction.

The synthetic pathways towards Pd-II complexes of functionalized bidentate diphenylphosphane ligands of the type [Pd(ligand)(anion)(2)] and [Pd(ligand)(2)](anion)(2) have been investigated. Eighteen different ligands have been used in combination with strongly (acetate, OAc-) or weakly (tosylate, OTs-) coordinating anions, The solid-state structure of some representative complexes was determined with X-ray crystallography. It is shown that the solid-state structures are fully retained in solution, The formation of [Pd(ligand)-(anion)(2)]-type complexes was studied in detail by H-1- and P-31-NMR spectroscopy. Depending on the Ligand structure, the complex is formed instantaneously, via a polynuclear intermediate or is not formed at all. Complex formation is demonstrated to depend on the length and rigidity of the ligand backbone and on the steric bulk at the ortho position of the phenyl rings on phosphorus, It was also found that the coordinating ability of the anions can alter the structure of the kinetic and/or thermodynamic product.

A new catalytic method has been investigated to obtain either O- or C-allylated phenolic products using allyl alcohol or diallyl ether as the allyl donor. With the use of new cationic ruthenium(II) complexes as catalyst, both reactions can be performed with good selectivity. Active cationic Ru(II) complexes, having cyclopentadienyl and bidentate phosphine ligands are generated from the corresponding Ru(II) chloride complexes with a silver salt. The structures of three novel (diphosphine)Ru(II)CpCl catalyst precursor complexes are reported. It appears that the structure of the bidentate ligand has a major influence on catalytic activity as well as chemoselectivity. In addition, a strong cocatalytic effect of small amounts of acid is revealed. Model experiments are described that have been used to build a reaction network that explains the origin and evolution in time of both O-allylated and C-allylated phenolic products. Some mechanistic implications of the observed structure vs. performance relation of the [(diphosphine)RuCp]+ complexes and the cocatalytic role of added protons are discussed.