The paper presents an overview of the work conducted in our group on the synthesis of a novel class of homogeneous and immobilized Ru-complexes containing Schiff bases as O, N-bidentate ligands benefiting from a versatile, quite general and thoroughly exemplified two-step procedure. The new Ru-complexes with improved stability incorporate a variety of Schiff bases, associated with traditional inorganic and organic ligands such as chloride, phosphanes, arenes, cyclodienes, NHC etc., and different carbenes (alkylidene, vinylidene, allenylidene and indenylidene). By a proper choice of the Schiff base, useful physical and chemical properties of the derived Ru-complexes could be induced resulting in tunable catalytic activity for metathesis and related processes. A pertinent example is the latency of selected Schiff base Ru catalysts which by becoming active only under specific conditions (heat or acid activation) are ideal for industrial applications, e.g. reaction injection molding processes. The synthetic approaches that are critically discussed in this chapter have led to a diversity of Ru-complexes of which several members have risen to the rank of commercial catalysts.
Keywords: Organometallic chemistry, ruthenium, ruthenium carbenes, ruthenium vinylidenes, ruthenium allenylidenes, ruthenium indenylidenes, ruthenium arenes, ruthenium hydrides, schiff base ligands, homogeneous catalysis, heterogeneous catalysis, olefin metathesis, ring closing metathesis, ring opening metathesis, cross metathesis, latent catalyst, kharash addition, atom transfer radical polymerization, isomerization, vinyl ester synthesis.