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 (κ²-<b>L</b>)RE(η²-C₂B₁₀H₁₀)·(THF)₃ [<b>L</b> = 1-(2-N-C₅H₁₀NCH₂CH₂)-3-(2,6-^<i>i</i>Pr₂C₆H₃N═CH)-C₈H₄N, RE = Lu(<b>1a</b>), Yb(<b>1b</b>), Er(<b>1c</b>), Y(<b>1d</b>), Dy(<b>1e</b>)] bearing the indol-2-yl electrophilic carbon and carboryne-based strongly polarized metallacyclopropanes have been synthesized. Structures of complexes <b>1</b> are further confirmed by single-crystal X-ray diffraction and DFT theoretical calculations. It is found that complexes <b>1</b> have remarkable reactivity toward different polar unsaturated small molecules, elemental sulfur, and selenium to provide different products (<b>2-15</b>) through the selective reactions of the RE-C_cage, and RE-C_2-ind 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.