A Bis‐Polydentate Oxamate‐Based Achiral Ligand That Can Stabilize a Macrocyclic Mixed Valence Compound or Induce a 1D Helical Chain

Abstract

The reaction of the N‐(2‐hydroxyphenyl)oxamate ligand (ohpma) has been investigated with cobalt(II) and copper(II) ions. It has led to two coordination compounds, (TMA)3[{CoIII(ohpma)2CoII(MeOH)2}3]·10H2O·5MeOH (1) and (HNEt3)[Cu(ohpma)] (2). Both compounds have been characterized by single‐crystal X‐ray diffraction and magnetometry. The X‐ray diffraction studies have revealed atypical structures that are not commonly observed in oxamate coordination chemistry with a macrocyclic arrangement for the mixed‐valence cobalt‐based complex 1, and a helical chiral chain for compound 2. In the latter, the bis‐polydentate nature of the (ohpma)3– ligand with distinct tridentate and bidentate coordination sites creates a chirogenic center on the copper ion. The investigation of the magnetic properties shows for complex 1 a single‐molecule magnet behavior detectable under static field, while antiferromagnetic interactions dominate the behavior of 2.