Carbon-Carbon Bond Coupling of Vinyl Molecules with an Allenyl Ligand at a Diruthenium Complex

The room-temperature reactions of the diruthenium μ-allenyl complex [Ru2Cp2(CO)2(NCMe){μ-η1:η2-CH═C═CMe2}]BF4, 3-NCMe, with a series of alkenes, RCH═CH2, afforded the complexes [Ru2Cp2(CO)2{μ-η3:η2-CH(R)CHC(Me)C(Me)CH2}]BF4 (R═Ph, 4; 4-C6H4Me, 5; Me, 6; nBu, 7; CO2Me, 8; and H, 9), containing an uncommon pentacarbon alkenyl-allyl ligand. Cross experiments with deuterated reagents, i.e., [Ru2Cp2(CO)2(NCMe){μ-η1:η2-CD═C═CMe2}]BF4 (3b-NCMe) and CD2═CD(C6H5) (styrene-d3), revealed that the formation of 4–9 is initiated by an attack of the alkene to the central carbon of the allenyl moiety, triggering two distinct C–H activation processes. Compounds 4–9 were characterized by analytical and spectroscopic methods and by single-crystal X-ray diffraction in the cases of 4, 7, and 8. Reported here is the clean coupling on a metallic scaffold between two C2 and C3 functions invoked in Fischer–Tropsch mechanistic models.