Solvothermal Synthesis of Oxamate-Based Helicate: Temperature Dependence of the Hydrogen Bond Structuring in the Solid

Solvothermal synthesis has been successfully tested as a new synthetic method toward the formation of oxamate-based coordination compounds. The reaction of 1,3-benzenedioxamic acid (H4mpba) with divalent metal ions has afforded the dinuclear compounds TBA2­[Co2­(H2mpba)3]·​2DMF·​5H2O (1a), (HNEt3)2­[Co2­(H2mpba)3]·​6DMF·​5H2O (1b), TBA2­[Ni2­(H2mpba)3]·​2DMF·​2.5H2O (2), and (HNEt3)2­[Co2­(H2mpba)3] (3). Although the 3:2 ligand to metal ratio is known for the (mpba)4– ligand under bench conditions, these complexes are the first examples of oxamate-based helicate. Furthermore, crystallographic studies show a temperature-dependent hydrogen bond structuring that leads to racemic or chiral hexagonal 3D networks.