New in situ generated acylhydrazidate-coordinated complexes: Syntheses, structural characterizations and magnetic properties

The present study reports the successful synthesis of three new magnetic coordination polymers, namely [Mn(BPTH)(H2O)]n (1), [Co(BPTH)(phen)]n (2), and [Co(BPTA)(phen)(H2O)2]n (3), through a solvothermal method (H2BPTH = biphenyl-3,3’,4,4’-tetracarboxyhydrazide, H2BPTA = biphenyl-3,3’,4,4’-tetracarboxylic acid, phen = 1,10-phenanthroline). In compounds 1 and 2, the bishydrazide ligand H2BPTH is formed by in situ acylation of H2BPTA with hydrazine hydrate. All the three title compounds contain M2O2 clusters (M=Mn(1), Co(2) and Co(3)). In compound 1, the amido-oxygen atoms O1 coordinate with Mn2+ to form a Mn2O2 cluster, while the adjacent Mn2O2 cluster is interconnected by the ligand's oxygen atoms O3 and O4, resulting in an infinite expansion into a 3D network structure. Compound 2 exhibits a 1D chain structure containing Co2O2 clusters, which further extends into a 2D supramolecular layer through π···π stacking interactions. Compound 3 comprises adjacent Co2O2 clusters interconnected by oxygen atoms O1, O2, and O5 on the ligand to form a 2D layered architecture. The 2D layers are linked through intermolecular O–H···O hydrogen bonds of H2BPTA ligands to form a 3D supramolecular network. Magnetic measurements reveal weak ferromagnetic behavior for compound 1 while compounds 2 and 3 exhibit weak antiferromagnetic interactions at different temperatures. Overall, this research presents new insights into the design and synthesis of coordination polymers with diverse structures and magnetic properties.