Reactivity of homodinuclear rare-earth metal complexes with an indol-2-yl-based pincer ligand toward nitrogen- and oxygen-containing compounds

Abstract

Diverse reactivity of homodinuclear rare-earth metal alkyl complexes (rare-earth metals = Gd, Dy, Y, Er, Yb, and Lu) supported by an indol-2-yl-based pincer ligand with nitrogen- and oxygen-containing organic compounds has been explored, resulting in the isolation and characterization of a range of dinuclear rare-earth metal complexes with different functional groups. Donor substrates such as ^tBuCN, DMAP, or Ph₃PO simply displaced the coordinated THF molecules in the complexes, while 1,2-dimethoxyethane (DME) resulted in the formation of a cis-dialkyl complex. The C–H activation of Ph₂CHCN (the α-C–H bond of nitrile), N-substituted imidazoles, o-carborane and the N–H bond activation of amines afford rare metal complexes featuring aza-allenyl moieties, unique amido-enolate dianions, o-carboryne-bridged species and a cis-configured bulky 2,6-diisopropylanilido moiety, respectively. Moreover, redox reactions between the metal complexes and Ph₂X₂ (X = S and Se) yield the corresponding dinuclear complexes bearing trans-configured phenylchalcogenolate groups. Notably, insertion of Ph₂CO or PhNCO into both the RE–CH₂SiMe₃ and RE–C_ind bonds generates dinuclear complexes with distinct coordination environments. Novel imidazole- and bipyridine-indole-functionalized groups were unprecedentedly obtained from the reactions of the metal complexes with N-phenyl imidazole and bipyridine. As a result, the indol-2-yl imido/amido pincer ligand provides a direct route to dinuclear complexes for probing bimetallic synergistic effects in catalysis.