Synthesis and characterisation of heterometallic trinuclear copper(II) and zinc(II) complexes derived from bis(2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone

► Heterotrinuclear complexes have been synthesized and characterized. ► The M-M interaction in the complexes: (1) > (2) >> (3) (no M-M interaction). ► The ligand is present in enol form in all of the complexes. ► Copper centre has dx2-y2 orbital as the ground state in all of the complexes. ► Copper has tetragonally distorted octahedral and square pyramidal stereochemistries.