Synthesis, crystal structures and magnetic properties of two Ni-Dy heterometallic complexes with the structural topologies regulated by employing different Schiff base ligands

•Topologies of Ni-Dy complexes were transformed from “V”-shape to “butterfly”-shape.•“V”-shaped NiII2DyIII complex shows slow magnetic relaxation behavior.•Directions of the easy magnetization axes of DyIII in two complexes were estimated.