In Situ Ligand Formation in the Synthetic Processes from Mononuclear Dy(III) Compounds to Binuclear Dy(III) Compounds: Synthesis, Structure, Magnetic Behavior, and Theoretical Analysis.

Guided by the self-assembled process and mechanism, the strategy of in situ Schiff base reaction would be capable of bringing a feasible method to construct and synthesize lanthanide compounds with distinct structures and magnetic properties. A mononuclear Dy(III) compound was synthesized through a multidentate Schiff base ligand and a chelating β-diketonate ligand, which was named as [Dy(L)(bppd)]·CHOH [; HL = ,'-bis(2-hydroxy-5-methyl-3-formylbenzyl)-,'-bis(pyridin-2-ylmethyl)ethylenediamine and bppd = 3-bis(pyridin-2-yl)propane-1,3-dione]. Furthermore, a new binuclear Dy(III) compound, [Dy(HLox)(bppd)]·8CHOH [; HLox = ,'-bis[2-hydroxy-5-methyl-3-(hydroxyiminomethyl)benzyl]-,'-bis(pyridin-2-ylmethyl)ethylenediamine], was obtained via an in situ synthetic process. Under similar synthetic conditions, [Dy(L)(ctbd)] [; ctbd = 1-(4-chlorophenyl)-4,4,4-trifluoro-1,3-butanedione] and [Dy(HLox)(ctbd)]·CHOH·CHO () were synthesized by modifying the β-diketonate ligand and in situ Schiff base reaction. Compound is a mononuclear configuration, while compound exhibits a binuclear Dy(III) unit. Therein, formylbenzyl groups of HL in and were changed to (hydroxyiminomethyl)benzyl groups in and , respectively. In isomorphous and , two Dy(III) centers are connected through two phenol O atoms of the HLox ligand to form a binuclear structure. Eight-coordinated Dy(III) ions with different distortions can be observed in -. The crystals of and suffered dissolution/precipitation to obtain and , respectively. The relationship between the structure and magnetism in compounds - was discussed through the combination of structural, experimental, and theoretical investigations. Especially, the rates of quantum tunneling of magnetization of - were theoretically predicted and are consistent with the experimental results. For and , the theoretically calculated dipolar parameters are consistent with the experimental observation of weak ferromagnetic coupling.