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