Structural Characterization of Heterodinuclear ZnII-LnIII Complexes (Ln\u2009=\u2009Pr, Nd) with a Ring-Contracted H2valdien-Derived Schiff Base Ligand

Shabana Noor,Rüdiger W Seidel,Fehmeeda Khatoon,Sarvendra Kumar,Richard Goddard

doi:10.1007/s10870-021-00891-4

Abstract

Synthesis and structural characterization of two heterodinuclear ZnII-LnIII complexes with the formula [ZnLn(HL)(µ-OAc)(NO3)2(H2O)x(MeOH)1-x]NO3 · n H2O · n MeOH [Ln = Pr (1), Nd (2)] and the crystal and molecular structure of [ZnNd(HL)(µ-OAc)(NO3)2(H2O)] [ZnNd(HL)(OAc)(NO3)2(H2O)](NO3)2 · n H2O · n MeOH (3) are reported. The asymmetrical compartmental ligand (E)-2-(1-(2-((2-hydroxy-3-methoxybenzylidene)amino)-ethyl)imidazolidin-2-yl)-6-methoxyphenol (H2L) is formed from N1,N3-bis(3-methoxysalicylidene)diethylenetriamine (H2valdien) through intramolecular aminal formation, resulting in a peripheral imidazoline ring. The structures of 1–3 were revealed by X-ray crystallography. The smaller ZnII ion occupies the inner N2O2 compartment of the ligand, whereas the larger and more oxophilic LnIII ions are found in the outer O2O2’ site.Graphic Synthesis and structural characterization of two heterodinuclear ZnII-LnIII complexes (Ln = Pr, Nd) bearing an asymmetrical compartmental ligand formed in situ from N1,N3-bis(3-methoxysalicylidene)diethylenetriamine (H2valdien) through intramolecular aminal formation are reported.

Highlights

Acyclic and macrocyclic Schiff base ligands are among the most extensively used ligands in coordination chemistry [1]
Schiff bases can be readily prepared in good yields through condensation of primary amines with aldehyde or ketones
Owing to the ease of their synthesis, their versatility and ability to form stable complexes with almost all transition metals, Schiff base ligands have enormously contributed to the development of coordination chemistry and their transition metal complexes have been important in bioinorganic chemistry, magnetochemistry, catalysis [2,3,4] and biomedical and related applications [5]

Summary

Introduction

Acyclic and macrocyclic Schiff base ligands are among the most extensively used ligands in coordination chemistry [1]. Polydentate Schiff base chelate ligands derived from condensation of 2-hydroxy-3-methoxybenzaldehyde (o-vanillin) or derivatives as aldehyde component with polyamines have been exploited for the synthesis of homoand heterodinuclear complexes. These have attracted research attention because of interesting properties such as magnetism and luminescence [6,7,8,9,10,11,12,13,14,15,16,17,18]. The H 2valdien ligand has been encountered in a chelate-spacerchelate bridging mode in dinuclear complexes with the aliphatic secondary amine linkages remaining unbound to the metal ions [27,28,29,30]

Methods

Results

Conclusion