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.

Graphical abstractThe synthesis of the heterobimetallic compounds (p-cymene)[(η5-C5H5)(μ-η5:η1-C5H4(CH2)2PR2)TaCl2]RuCl2 (3–4) is described. The air oxidation of these bimetallic species 3–4, leads to the cationic hydroxo tantalum ruthenium derivatives 5–6. The latter are easily deprotonated to afford the oxo analogues 7–8. These bimetallic complexes 3–8 have been involved in catalytic cyclopropanation of styrene.Figure optionsDownload full-size imageDownload as PowerPoint slide