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.

Solvothermal synthesis, structure and magnetic properties of heterometallic coordination polymers based on a phenolato-oxamato co-bidentate-tridentate ligand

“…The N-(2-hydoxyphenyl)oxamic acid hydrate, mixed sodium salt (H2.5Na0.5-ohpma•0.5H2O) was prepared following the reported procedure. 18 Synthesis.…”

“…17 These observations led us to recently investigate the reactivity of the ortho-subsituted N-(2-hydoxyphenyl)oxamic acid (H3ohpma). 18 We have obtained two homometallic compounds also displaying a whole coordination mode with copper or cobalt ions (Scheme 1h). Nevertheless, we failed at preparing heterometallic systems, and besides the compounds made of Cu(II) and alkaline earth cations, 11 none of the compounds reported so far with phenyloxamate-based ligands bearing additional coordinating groups are heterometallic systems.…”

Solvothermal Synthesis, Temperature-Dependent Structural Study, and Magnetic Characterization of a Multipolydentate Oxamate-Based 2D Coordination Network

“…Investigating the reactivity of these multipolydentate ligands will further expand the morphology of the coordination architectures it is possible to generate and access with oxamate ligands. For example, the use of amino acid based oxamate ligands gives access to new porous frameworks with remarkable properties. − On the other hand, phenolic and benzoic derivatives of the oxamate ligands seem to pose a greater synthetic challenge for the observation of fully coordinating ligands and/or the preparation of heterometallic systems. − Following our work on the 2-hydroxyphenyloxamate ligand under bench conditions, we had investigated solvothermal conditions to succeed in crystallizing copper­(II)-based heterobimetallic compounds. This proved efficient with both the 2-hydroxyphenyloxamate and the 2-carboxyphenyloxamate, yet only 1D coordination polymers were obtained. , To increase the dimensionality of our edifices, we have naturally moved to a para -substitued phenyloxamate, and started to investigate the 4-(ethyloxamate)­benzoic acid, H 2 Et-paba.…”

“…18−21 On the other hand, phenolic and benzoic derivatives of the oxamate ligands seem to pose a greater synthetic challenge for the observation of fully coordinating ligands and/or the preparation of heterometallic systems. 22−29 Following our work on the 2hydroxyphenyloxamate ligand under bench conditions, 29 we had investigated solvothermal conditions to succeed in crystallizing copper(II)-based heterobimetallic compounds. This proved efficient with both the 2-hydroxyphenyloxamate and the 2-carboxyphenyloxamate, yet only 1D coordination polymers were obtained.…”

Synthesis, structure and magnetic properties of an oxamate-based 1D coordination polymer built on pentametallic links

“…Recently, this led us to investigate the reactivity of the 2-hydroyphenyloxamate ligand and we have observed the formation of two atypical structures for phenyloxamate-related chemistry: a hexametallic macrocyclic coordination ring and of a chiral coordination polymer. [34] To further this reactivity investigation, we have also decided to revisit solvothermal reactions. Indeed, prior attempts by others and us at using this technique for reacting oxamate ligands highlighted difficulties in obtaining a fully deprotonated, i.e.…”