In situ syntheses, crystal structures and magnetic properties of CuII and MnII coordination assemblies based on a novel heteroalicyclic dicarboxylate tecton and N-donor co-ligands

Abstract

This work focuses on coordination chemistry of a heteroalicyclic dicarboxylate ligand 5,6-dihydro-1,4-dithiin-2,3-dicarboxylate (L) with transition metals in the presence of N-donor co-ligands. A series of five Cu^II and Mn^II coordination complexes with L building blocks and different chelating/bridging co-ligands have been prepared, namely [Cu(L)(phen)]_n (1), [Cu(L)(4bpy)(H₂O)]_n (2), {[Cu₂(L)₂(μ₃-OH)](H₂dabco)_0.5(H₂O)}_n (3), {[Mn₂(L)(phen)₄](H₂O)₂(ClO₄)₂}₂ (4), and {[Mn₂(L)(2bpy)₄](2bpy)_0.5(ClO₄)₂}₂ (5) (phen = 1,10-phenanthroline, 4bpy = 4,4′-bipyridine, dabco = 1,4-diazabicyclo[2,2,2]octane, 2bpy = 2,2′-bipyridine), in which the ligand L is obtained by an in situhydrolysis reaction of 5,6-dihydro-1,4-dithiin-2,3-dicarboxylic anhydride in the presence of lithium hydroxide. Single-crystal X-ray diffraction reveals that these complexes display a variety of coordination motifs, from the discrete tetranuclear species (4 and 5) to infinite 1-D arrays (1 and 3) and 2-D → 3-D polycatenated architecture (2), which are regulated by the multiple coordination modes of L. Furthermore, the introduction of auxiliary N-heterocyclic ligands plays a critical role in extending the dimensionality of these metallosupramolecular systems via coordination and/or secondary interactions such as hydrogen bonds and aromatic stacking. The magnetic properties and thermal stability of these complexes have also been investigated and discussed in detail.