Unprecedented family of heterometallic LnIII[18-metallacrown-6] complexes: syntheses, structures, and magnetic properties

Abstract

Herein, a new family of Ln^III[18-metallacrown-6] compounds with the formula [Fe₆O₂Ln(tBu-sao)₆(OH)(MeO)₄(MeOH)(H₂O)]·6MeOH [Ln = Dy^III (1), Tb^III (2), Gd^III (3), and Y^III (4), tBu-saoH₂ = 3,5-di-tert-butylsalicylaldoxime] was synthesized through one-pot reactions using tBu-saoH₂, Fe(ClO₄)₃·6H₂O, and Ln(NO₃)₃·6H₂O. The four compounds are isostructural, and the encapsulation of a Ln ion in the ring cavity of 18-metallacrown-6 (18-MC-6) was exhibited for the first time. The structural analysis shows a ship-like 18-MC-6 core with a beset lanthanide ion connecting six ring oxygen atoms (O_MC). Magnetic measurements reveal domain antiferromagnetic coupling interactions between metal ions and field-dependent slow magnetic relaxation in 1–3.