The first lutetacyclopentadienes: synthesis, structure, and diversified insertion/C-H activation reactivity

The first well-defined lutetacyclopentadienes are synthesised from pentamethylcyclopentadienyl lithium (Cp*Li), 1,4-dilithio-1,3-butadienes, and LuCl3. The lutetacyclopentadiene shows excellent reactivity towards some small molecules, such as pivalaldehyde, Se, carbon dioxide, and isonitrile to efficiently construct 3-, 5-, 7-, 8-, and 9-membered rare-earth metallacycles. Both monoinsertion and double-insertion of two Lu-Csp2 bonds are observed. Specially, the reaction between lutetacyclopentadiene and isonitrile afforded [3,5,5]-fused metallacycles. The distinguished reactivity can be attributed to the highly ionic character and the cooperative reactivity of two Lu-Csp2 bonds.