A Quasi-Liner {Mn^IIDy^IIIMn^II} Cluster Featuring In Situ Schiff Base Ligand Transformation

Abstract

Employing tripodal Schiff base ligand of tris[4-(2-hydroxy-3-methoxyphenyl)-3-aza-3-butenyl]amine (H₃L¹) and auxiliary ligand of 2-hydroxy-5-chlorobenzaldehyde, a 3d–4f cluster of $\left[ {{\text{Dy}}^{{{\text{III}}}} {{{\text{Mn}}}}_{ 2}^{{{\text{II}}}} \left( {{{\text{L}}}^{ 2} } \right)_{ 2} } \right]\left[ {{{\text{NO}}}_{ 3} } \right] \cdot 5 {{{\text{CH}}}}_{ 3} {{{\text{OH}}}}$ (1) was synthesized. Intriguingly, the H₃L¹ ligand has transformed into another Schiff base ligand of {N-[4-(2-hydroxy-5-chlorophenyl)-3-aza-3-butenyl]-N′,N′′-bis[4-(2-hydroxy-3-methoxyphenyl)-3-aza-3-butenyl]}amine (H₃L²) in situ during the coordination process, that one of terminal groups of H₃L¹ ligand was substituted. A pair of such (L²)³⁻ ligands chelate a Dy^III and two Mn^II ions to form a quasi-liner {Mn^IIDy^IIIMn^II} skeleton of 1, in which the adjacent Mn^II and Dy^III ions were bridged by three O_phenol. To the best of our knowledge, this in situ substitution of the terminal group of Schiff base ligand has not been reported in previous literature. DC magnetic susceptibility measurements were conducted on 1, revealing the weak antiferromagnetic interactions between the Dy^III and Mn^II centers.

Graphic Abstract

A quasi-liner a {Mn^IIDy^IIIMn^II} cluster has been constructed from tripodal Schiff base ligand of H₃L¹. The H₃L¹ ligands underwent an in situ substitution in the coordination, which has been not reported in previous literature so far as we known. Magnetic studies reveal the weak antiferromagnetic interactions between Dy^III and Mn^II ions.