Bimetallic complexes with ruthenium and tantalocene moieties: Synthesis and use in a catalytic cyclopropanation reaction

The reaction of the tantalocene dichloride monophosphines (1–2) with the binuclear complex [(p-cymene)RuCl2]2 gives the heterobimetallic compounds (p-cymene)[(η5-C5H5)(μ-η5:η1-C5H4(CH2)2PR2)TaCl2]RuCl2 (3–4). The air oxidation of these bimetallic species 3–4, leads to the cationic hydroxo tantalum ruthenium derivatives 5–6. The last ones are easily deprotonated by a base to afford the oxo analogues 7–8. A preliminary assessment in catalytic cyclopropanation of styrene with tantalum ruthenium bimetallic complexes 3–8 as precatalysts revealed a cooperative effect with a subtle role of the early metal fragment.