Acid-catalysed C–H activation of ethene and linking of alkynes at a diruthenium centre

Abstract

The RuRu double-bonded µ-alkyne complexes [Ru₂(µ-CO)(µ-RC₂R)(η-C₅H₅)₂] react slowly or not at all with ethene and alkynes even under forcing conditions, but in the presence of acid C–H activation of ethene and alkyne-linking occur rapidly at room temperature to give di-µ-vinyl complexes [Ru₂(CO)(µ-CRCHR)(µ-CHCH₂)(η-C₅H₅)₂] and metallacyclopentadiene complexes [Ru₂(CO)(µ-C₄R₄)(η-C₅H₅)₂] respectively; the acid catalysis is shown to proceed via the formation of a RuRu triple-bonded µ-vinyl cation [Ru₂(µ-CO)(µ-CRCHR)(η-C₅H₅)₂]⁺.