Reactions of [Ru(CO)3Cl2]2 with aromatic nitrogen donor ligands in alcoholic media

The reactions of mono‐ and bidentate aromatic nitrogen‐containing ligands with [Ru(CO)3Cl2]2 in alcohols have been studied. In alcoholic media the nitrogen ligands act as bases promoting acidic behaviour of alcohols and the formation of alkoxy carbonyls [Ru(N–N)(CO)2Cl(COOR)] and [Ru(N)2(CO)2Cl(COOR)]. Other products are monomers of type [Ru(N)(CO)3Cl2], bridged complexes such as [Ru(CO)3Cl2]2(N), and ion pairs of the type [Ru(CO)3Cl3]− [Ru(N–N)(CO)3Cl]+ (N–N = chelating aromatic nitrogen ligand, N = non‐chelating or bridging ligand). The reaction and the product distribution can be controlled by adjusting the reaction stoichiometry. The reactivity of the new ruthenium complexes was tested in 1‐hexene hydroformylation. The activity can be associated with the degree of stability of the complexes and the ruthenium–ligand interaction. Chelating or bridging nitrogen ligands suppresses the activity strongly compared with the bare ruthenium carbonyl chloride, while the decrease in activity is less pronounced with monodentate ligands. A plausible catalytic cycle is proposed and discussed in terms of ligand–ruthenium interactions. The reactivity of the ligands as well as the catalytic cycle was studied in detail using the computational DFT methods. Copyright © 2005 John Wiley & Sons, Ltd. The reactions of mono andbidentate aromatic nitrogen containing ligands with [Ru(CO)3Cl2]2 in alcohol solutions have been studied. Acid‐base behavior of alcohols and aromatic polypyridines promotes the formation of several organometallic compounds. The reactivity of the new complexes have been tested in 1‐hexene hydroformylation.