Synthesis of chiral highly hindered cyclopentadienylruthenium compounds

Optically active highly hindered half-sandwich ruthenium(II) compounds with C2-symmetric cyclopentadienyl ligands were synthesized from the ligand precursors, 4 and 5, which were derived from (−)-β-pinene. Thus, the reaction of the ligands with triruthenium dodecacarbonyl produced ruthenium compounds, 10 and 11, after oxidative treatment. These compounds were characterized by single crystal X-ray crystallography.