Chiral Erbium(III) Complexes: Single-Molecule Magnet Behavior, Chirality, and Nuclearity Control.

ABSTRACT

The reactions of chiral ligand (R)/(S)-1,1'-binaphthyl-2,2'-diyl phosphate (R-HL/S-HL) and ErCl3·6H2O afford two pairs of di- and tetranuclear enantiomers [Er2(R/S-L)4(EtOH)6]Cl2·6.5EtOH (R-1, S-1) and [Er4(PO4)(R/S-L)8(EtOH)3(H2O)]2Cl(OH)·15EtOH·11H2O (R-2, S-2). The nuclearity of these complexes is controllable and depends on the reaction temperature with a template effect. Their chirality was evidenced by circular dichroism (CD) spectra. R-1 exhibits two magnetic relaxation pathways under a zero field, with an apparent barrier of 40 K. Ab initio calculations revealed a ferromagnetic dipolar interaction between these two Er(III) ions, the equatorial nature of the ligand field, and the probable origin of the two relaxations.