Synthesis, Structure, and Property of Tris(biphenyldiyl)yttrium(III) Tris(binaphthyldiyl)yttrium(III) and Tris(binaphthyldiyl)erbium(III) Complexes
来源：ACS Publications
In the recent development of homoleptic σ-hydrocarbyl rare-earth metal complexes focusing on reactivity and catalytic activity, rare-earth metal complexes with a variety of alkyl ligands have been synthesized, and the principle for designing thermally stable σ-hydrocarbyl rare-earth metal complexes has been established. Nevertheless, there has been no report of homoleptic rare-earth metal complexes comprising only identical bidentate σ-hydrocarbyl ligands. Herein, we present homoleptic σ-hydrocarbyl rare-earth metal complexes possessing bidentate biaryldiyl ligands, tris(biphenyl-2,2′-diyl)yttrium(III) complex 1, tris(1,1′-binaphthyl-2,2′-diyl)yttrium(III) complex 2, and tris(1,1′-binaphthyl-2,2′-diyl)erbium(III) complex 3. Single-crystal X-ray crystallography revealed the trigonal prismatic geometry of 1, along with the trigonal antiprismatic geometry of 2 and 3, each constructed through three-centered two-electron bonds among the rare-earth metal, ipso-carbon, and lithium. The static and dynamic magnetic properties of 3 were investigated in the solid state, showing a slow magnetic relaxation typical of single-molecule magnets. The fitting of the magnetic behavior of 3 and the ab initio theoretical calculations indicated that the magnetic relaxation of 3 occurs primarily through a Raman relaxation process.
In this report, we present a new series of homoleptic rare-earth metal complexes having only three identical bidentate σ-hydrocarbyl ligands: tris(biphenyl-2,2′-diyl)yttrium(III) complex (Li3Y(bph)3 (1)), and the π-extended analogs, tris(1,1′-binaphthyl-2,2′-diyl)yttrium(III) and tris(1,1′-binaphthyl-2,2′-diyl)erbium(III) complexes (Li3Y(bnph)3 (2) and Li3Er(bnph)3 (3)). These complexes showed sufficient thermal stability to be isolated, and their structure was determined by X-ray crystallography. Complexes 2 and 3 were obtained as a single diastereomer in racemic form, each consisting of a pair of mirror isomers arising from the axial chirality of the binaphthyl skeletons. The Er analog 3 was characterized by means of direct current (DC) and alternating current (AC) magnetic measurements and shows a field-induced slow magnetic relaxation typical for single-molecule magnets.