Modular synthesis of pentaarylcyclopentadienyl Ru-based molecular machines via sequential Pd-catalysed cross couplings.

A dissymmetric piano-stool ruthenium(ii) complex bearing different halogens on the rotor part was efficiently prepared and subsequently used as a key building block in the modular synthesis of potential rotative molecular machines via palladium-catalysed "Sonogashira/Suzuki-Miyaura" sequences. Applying this novel synthetic route to various cross-coupling partners, prototypes of molecular winches and cogwheels for gear applications, specifically designed for studies at the single-molecule scale, were efficiently obtained.