Transition-metal-catalyzed C-H functionalization is becoming a general and straightforward strategy for the construction of car-bon-carbon and carbon-heteroatom bonds in modern organic syn-thesis.In this regard,ligands often play a key role for the C-H functionalization processes.In addition to those neutral ligands such as phosphorus-type ligands,N-heterocyclic carbenes,etc.,anionic type ligands derived from substituted cyclopentadienes have also received much attention.Their unique properties,includ-ing strong π-donation and stability,are responsible for forming robust CpxM(M = Co,Rh,Ir,Ru,etc.)catalysts.Moreover,these Cp ligands display superior performance such as enhanced reactiv-ity,improved regioselectivity and diastereoselectivity through the modulation of the electronic and steric properties of the Cp rings.