Dynamic, reactivity and catalytic behavior of pseudo-undercoordinated ruthenium and rhodium complexes stabilized by intramolecular solvents

Abstract

The fluxional behavior of pseudo-undercoordinated ruthenium complexes provided with bifunctional ether-phosphine ligands which compete for a common coordination site at the metal center is reviewed. The quantitative determination of this dynamic exchange by temperature-dependent 31P NMR spectroscopy and line-shape analyses gives access to kinetic and thermodynamic data. From these, valuable information concerning the different chelating abilities of various ether-phosphines is available in dependence on both O-nucleophilicity and phosphorus basicity. Based on these experimental results, appropriate (ether-phosphine)-ruthenium and rhodium complexes are presented showing high reactivity toward the activation of small molecules like hydrogen, sulfur dioxide, carbon dioxide, carbon disulfide, ethene and phenylacetylene. Moreover, their catalytic properties with respect to hydrogenations, carbonylations and carbon dioxide hydrogenation are discussed.