Rare-Earth Metal Complexes Bearing Electrophilic Carbon and Strongly Polarized Metallacyclopropane Moiety: Synthesis and Diverse Reactivity toward Small Molecules.

Metallacyclopropanes are highly strained and very reactive organometallics; the rare-earth metal complexes bearing both highly reactive electrophilic carbon and strongly polarized metallacyclopropanes are extremely rare. This type of rare-earth metal complexes (κ-)RE(η-CBH)·(THF) [ = 1-(2-N-CHNCHCH)-3-(2,6-PrCHN═CH)-CHN, RE = Lu(), Yb(), Er(), Y(), Dy()] bearing the indol-2-yl electrophilic carbon and carboryne-based strongly polarized metallacyclopropanes have been synthesized. Structures of complexes are further confirmed by single-crystal X-ray diffraction and DFT theoretical calculations. It is found that complexes have remarkable reactivity toward different polar unsaturated small molecules, elemental sulfur, and selenium to provide different products () through the selective reactions of the RE-C, and RE-C bonds with the given small molecules, respectively. The reactivities of these complexes are different from those of the reported rare-earth metallacyclopropenes and d-block metal-carborynes.