Synthesis of complexes with the polydentate ligand N,N′-bis(2-hydroxyphenyl)-pyridine-2,6-dicarboxamide

► We have synthesised and structurally characterised four new metal complexes containing the polydentate ligands system POPYH4. ► The unusual Zn(II) complex has been shown to consists of an unusual tetra-zinc core supported by three POPYH ligands each one of which links two adjacent zinc centres through two oxygen and two nitrogen donor atoms. ► In contract the Ni(II) and Pd(II) complexes described posses central square planar geometry in which the POPYH ligand are coordinated through the two deprotonated amido nitrogen atoms, the pyridine nitrogen.