The chemistry of 1,2,3,4,5-pentaphenylcyclopentadienyl hydrotris(indazolyl)borate ruthenium(II) complexes, building blocks for the construction of potential organometallic molecular motors

In recent years, we have developed a strategy to build electrically addressed molecular motors. The architecture of such compounds is centered around half-sandwich complexes of the family of pentaphenylcyclopentadienyl hydrotris(pyrazolyl)borate ruthenium(II). In this review article, we focus on the synthesis of various pentaphenylcyclopentadienyl ligands and on the peculiar reactivity of such hindered ligands in their coordination to a ruthenium(II) center. Finally, we report on the synthesis of the latest generation of fully equipped potential molecular motors. They bear ferrocene terminal electroactive groups linked to the central pentaphenylcyclopentadienyl ligand either by conjugated or insulating spacers, and are also functionalized to be anchored on various metallic or insulating surfaces in view of near-field microscopy experiments.