Self-Assembled Lanthanide Phosphinate Square Grids (Ln = Er, Dy, and Tb): Dy 4 Shows SMM/SMT and Tb 4 SMT Behavior.

Tetranuclear [2 × 2] square-grid-like Ln III clusters have been synthesized by reacting LnCl 3 ·6H 2 O salts with bis[α-hydroxy( p -bromophenyl)methyl]phosphinic acid [R 2 PO 2 H, where R = CH(OH)PhBr] and pivalic acid. Single-crystal X-ray diffraction studies show the formation of [Me 4 N] 2 [Ln 4 (μ 2 -η 1 :η 1 -PO 2 R 2 ) 8 (η 2 -CO 2 Bu t ) 4 (μ 4 -CO 3 )] [Ln = Er ( 1 ), Dy ( 2 ), and Tb ( 3 )]. Direct-current studies reveal significant ferromagnetic interactions between Dy III in 2 and Tb III in 3 and an antiferromagnetic interaction between Er III in 1 . Dynamic magnetic susceptibility measurements confirm a single-molecule magnet (SMM) behavior in both 0 and 1200 Oe applied magnetic fields for 2 . Complexes 2 and 3 show single molecular toroic (SMT) behavior with a mixed magnetic moment.