The synthesis, characterization, crystal structures and magnetic properties of isoskeletal heptanuclear disk-like M^II ₃Ln^III ₄ coordination clusters with the general formula [Co^II ₃Ln^III ₄(µ₃-OH)₆L₆(CF₃SO₃)][(CF₃SO₃)₅] where Ln = Gd (2), Y (3) and [Ni^II ₃Ln^III ₄(µ₃-OH)₆L₆(CF₃SO₃)][(CF₃SO₃)₅] where Ln = Dy (4), Gd (5), Y (6) are presented. All the compounds are stable in solution as confirmed by ESI-MS. Magnetic studies were performed for compounds 2, 4, 5 and 6 and indicate ferromagnetic coupling while the magnetocaloric properties of 5 are characterized by ΔS_m = –15.4 J kg^–1 K^–1 at T = 5.0 K and ΔT_ad = 5.9 K at T = 2.3 K, for µ₀ΔH = 7 T.