Rare-Earth Metalloligands for Low<b>-</b>Valent Cobalt Complexes: Fine Electronic Tuning <i>via</i> Co→RE Dative Interactions

Rare-earth metalloligand supported low-valent cobalt complexes were synthesized by utilizing a small-sized heptadentate phosphinomethylamine LsNH3 and a large-sized arene-anchored hexadentate phosphinomethylamine LlArH3 ligand precursors. The RE(III)-Co(−I)-N2 (RE = Sc, Lu, Y, Gd, La) complexes containing rare-earth metals including the smallest Sc and largest La were characterized by multinuclear NMR spectroscopy, X-ray diffraction analysis, electrochemistry, and computational studies. The Co(−I)→RE(III) dative interactions were all polarized with major contributions from the 3dz2 orbital of the cobalt center, which was slightly affected by the identity of rare-earth metalloligands. The IR spectroscopic data and redox potentials obtained from cyclic voltammetry revealed that the electronic property of the Co(−I) center was finely tuned by the rare-earth metalloligand, which was revealed by variation of the ligand systems containing LsN, LmN, and LlAr. Unlike the direct alteration of the electronic property of metal center via an ancillary ligand, such a series of rare-earth metalloligand represents a smooth strategy to tune the electronic property of transition metals

Rare-Earth Metalloligands for Low<b>-</b>Valent Cobalt Complexes: Fine Electronic Tuning <i>via</i> Co→RE Dative Interactions

Rare-earth metalloligand supported low-valent cobalt complexes were synthesized by utilizing a small-sized heptadentate phosphinomethylamine LsNH3 and a large-sized arene-anchored hexadentate phosphinomethylamine LlArH3 ligand precursors. The RE(III)-Co(−I)-N2 (RE = Sc, Lu, Y, Gd, La) complexes containing rare-earth metals including the smallest Sc and largest La were characterized by multinuclear NMR spectroscopy, X-ray diffraction analysis, electrochemistry, and computational studies. The Co(−I)→RE(III) dative interactions were all polarized with major contributions from the 3dz2 orbital of the cobalt center, which was slightly affected by the identity of rare-earth metalloligands. The IR spectroscopic data and redox potentials obtained from cyclic voltammetry revealed that the electronic property of the Co(−I) center was finely tuned by the rare-earth metalloligand, which was revealed by variation of the ligand systems containing LsN, LmN, and LlAr. Unlike the direct alteration of the electronic property of metal center via an ancillary ligand, such a series of rare-earth metalloligand represents a smooth strategy to tune the electronic property of transition metals

A Green and Efficient Solvent for Simultaneously Leaching Co and Li from Spent Li-Ion Batteries: Dicarboxylated Polyethylene Glycol

Recovery of high-valued metals such as Li and Co from spent Li-ion batteries is quite important for sustainability reasons. The novelty of this work was based on the view of molecular design, proposing a strategy that inserts another group between two −COOH groups on an organic acid to activate them. On this basis, a novel solvent dicarboxylated polyethylene glycol (dcPEG), i.e., HOOC–CH2(CH2CH2O)nCH2–COOH, was chosen to leach Li and Co from LiCoO2. Expectedly, HOOC–CH2(CH2CH2O)nCH2–COOH (n = 250), which was denoted as dcPEG250, showed appealing leaching performance without the help of H2O2 and quaternary ammonium salt. It can simultaneously extract Co and Li, and the leaching efficiency reached as high as almost 100% under the proper conditions. The excellent performance was ascribed to structural feature of dcPEG. The presence of main chain (CH2CH2O)n extended the distance between two −COOH groups at the ends, limited their intramolecular interaction, and activated the −COOH groups. Accordingly, the active H atom on the −COOH group can react with LiCoO2, and the active O atoms on ether (C–O–C) and carbonyl (CO) groups can coordinate with metals. In a word, this work could not only provide a promising solvent but also inspire researchers to engineer more novel solvents from the view of molecular design