Synthesis and characterization of new complexes of the type [Ru(CO) ₂Cl₂ (2-phenyl-1,8-naphthyridine-kN) (2-phenyl-1,8- naphthyridine-kN′)]. Preliminary applications in homogeneous catalysis

Novel ruthenium (II) complexes were prepared containing 2-phenyl-1,8-naphthyridine derivatives. The coordination modes of these ligands were modified by addition of coordinating solvents such as water into the ethanolic reaction media. Under these conditions 1,8-naphthyridine (napy) moieties act as monodentade ligands forming unusual [Ru(CO)2Cl 2(η1-2-phenyl-1,8-naphthyridine-kN) (η1-2-phenyl-1,8-naphthyridine-kN′)] complexes. The reaction was reproducible when different 2-phenyl-1,8-naphthyridine derivatives were used. On the other hand, when dry ethanol was used as the solvent we obtained complexes with napy moieties acting as a chelating ligand. The structures proposed for these complexes were supported by NMR spectra, and the presence of two ligands in the [Ru(CO)2Cl2(η 1-2-phenyl-1,8-naphthyridine-kN)(η1-2-phenyl-1, 8-naphthyridine-kN′)] type complexes was confirmed using elemental analysis. All complexes were tested as catalysts in the hydroformylation of styrene showing moderate activity in N,N′-dimethylformamide. Copyright © 2008 John Wiley & Sons, Ltd.