Synthesis of heptanuclear Ni4Dy3 coordination aggregate using tridentate ligand: X-ray structure, magnetism and theoretical studies

•A new {Ni4Dy3} heterometallic heptanuclear aggregate have been synthesized.•The molecular structure has been well characterized using X-ray analysis.•Complex core has a rare topology among the Ni–Ln family.•Magnetic susceptibility studies were done to understand the exchange interaction.•Detailed CASSCF calculation was done to validate the experimental magnetic data.