A ruthenium(II) allenylidene complex with a 4,5-diazafluorene functional group: A new building-block for organometallic molecular assemblies

The synthesis of the new ruthenium(II) allenylidene complex [ClRu(dppe)₂CCC₁₁H₆N₂][OTf] (4) (dppe = 1,2-bis(diphenylphosphino)ethane) terminated with a 4,5-diazafluorene ligand is reported. Further coordination of that metal allenylidene to ruthenium and rhenium moieties leads to the bimetallic adducts [ClRu(dppe)₂CCC₁₁H₆N₂{Ru(bpy)₂}][B(C₆F₅)₄]₃ (5a), [ClRu(dppe)₂CCC₁₁H₆N₂{Ru(^tBu-bpy)₂}][PF₆]₃ (5b) and [ClRu(dppe)₂CCC₁₁H₆N₂{Re(CO)₃Cl}][OTf] (6). Their optical and electrochemical properties show that the allenylidene moiety is an attractive molecular clip for the access to larger original redox-active homo/heteronuclear multi-component supramolecular assemblies. The X-ray crystal structure of the allenylidene metal building block is also described.