Synthesis, Structure, and Property of Tris(biphenyldiyl)yttrium(III) Tris(binaphthyldiyl)yttrium(III) and Tris(binaphthyldiyl)erbium(III) Complexes

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 <b>1</b>, tris(1,1'-binaphthyl-2,2'-diyl)yttrium(III) complex <b>2</b>, and tris(1,1'-binaphthyl-2,2'-diyl)erbium(III) complex <b>3</b>. Single-crystal X-ray crystallography revealed the trigonal prismatic geometry of <b>1</b>, along with the trigonal antiprismatic geometry of <b>2</b> and <b>3</b>, each constructed through three-centered two-electron bonds among the rare-earth metal, <i>ipso</i>-carbon, and lithium. The static and dynamic magnetic properties of <b>3</b> were investigated in the solid state, showing a slow magnetic relaxation typical of single-molecule magnets. The fitting of the magnetic behavior of <b>3</b> and the <i>ab initio</i> theoretical calculations indicated that the magnetic relaxation of <b>3</b> occurs primarily through a Raman relaxation process.