Heterodinuclear [Co-Ln] complexes of semicarbazide-arm bearing ligand: synthesis from the cleavage of starting [Co-Co] complex, structures and magnetic properties

Abstract

Heterometallic bridging potential of the anion of 1-(2-hydroxy-3-methoxybenzylidene) semicarbazide (HL) to CoII and four 4f ions have been examined during 4f ion coordination driven cleavage of [Co2(µ-OH2)(O2CCMe3)4(HO2CCMe3)4] (Co2-Piv) and scrambling...

New Candy-Shaped Hexanuclear CoII2CoIII2Gd2 Aggregate: Synthesis, Structures, and Magnetic Performance for Magnetocaloric Effect and Theoretical Understanding

“…The present type of synthesis was planned to explore the coordination- cum -cleavage reactivity of [Co 2 (μ-OH 2 )­(O 2 CCMe 3 ) 4 (HO 2 CCMe 3 ) 4 ] ( Co 2 -Piv ) with the chosen ligand system (H 3 L) in the presence of the Gd III ion and NEt 3 and thus, the bimetallic and synergistic coordination reactivity of H 3 L toward Co 2 -Piv and Gd­(NO 3 ) 3 ·6H 2 O. Though during the recent past, H 3 L was used for the synthesis of homo- and heterometallic aggregates Co II Co III , Co II 2 Co III , Mn III 3 Mn II , Mn III 2 Ni II 2 , Co III 2 Dy III 4 , Co III 2 Dy III , Co III 2 Dy III 2 , Mn III 4 Ln III 2 and Ln 4, nothing was known from the chosen synthetic strategy. − Our earlier attempts provided several unknown modes of aggregation involving different ligand systems and incorporation of cobalt and lanthanide ions. − Herein, a new reaction path is established to get the Co III 2 Co II 2 Gd 2 aggregate from the assembly of two metal ion capturing L 3– around four Co II/III and two Gd III ions. The cleavage of Co 2 -Piv by L 3– showed initial incorporation of two Co­(O 2 CCMe 3 ) + fragments within the ligand anion scaffold followed by trapping of two Gd 3+ ions and then finally a very unique top up coverage by two Co­(O 2 CCMe 3 ) 3 + units.…”

Synthesis, structures, and magnetic properties of butterfly-shaped hexanuclear [FeIII4LnIII2] single-molecule magnets

“…In recent decades, research on heterometallic complexes containing 3d-4f metal ions has attracted increasing attention from scientists. [1][2][3][4][5] Since 4f metal ions have different coordination modes and coordination abilities from 3d metal ions, 3d-4f coordination compounds show a variety of topological diversity. [6][7][8] Furthermore, transitions, transfers, and synergies between 3d and 4f metal ions and quantum size effects endow such compounds with unique physical and chemical properties.…”