Synthesis and Reactivity of the Rare-Earth Metal Complexes Bearing the Indol-2-yl-Based NCN Pincer Ligand.

The pincer rare-earth dialkyl complexes [-RE(CHSiMe) (RE = Lu(), Yb(), Er(), Y(), Dy())] with the indol-2-yl-based NCN pincer ligand were synthesized by the reactions of the proligand ( = 1-MeNCHCH-3-(2-PrCHN═CH)CHN) with RE(CHSiMe)(THF). These complexes exhibited a variety of reactivities toward organic compounds such as amines, triphenylphosphine ylide, -phenylimidazole, pyridine derivatives, and -carborane leading to -bond metathesis, migration insertion, and redox reaction products. The reactions of the dialkyl rare-earth metal complexes with -carborane afforded the novel NCN pincer-ligated carboryne-based metallacyclopropanes which reacted with diphenyl ketone to give insertion products of the RE-C and one of the RE-C bonds, while the reaction of the carboryne-based metallacyclopropanes with diphenyldiazomethane produced the di--metallacyclopentanes via the insertions of the N═N bond of the diphenyldiazomethane into two RE-C bonds and the RE-C bond. The reactions of the dialkyl complexes with 2 equiv of 2,2'-bipyridine afforded the pincer-ligated bis(2,2'-bipyridyl monoanionic radical) complexes via the homolytic redox reaction.