Two dimeric metal-oxo clusters, (Na-4[Co2Sb12(mu(3)-O)(6)(mu(3)-OH)(2)(mu 4-O)(3)(tartrate)(6)]center dot 19.5H(2)O)(2) (1) and KNa3[Ni2Sb12(mu(3)-O)(6)(mu-OH)(2)(mu(4)-O)(3)(tartrate)(6)]center dot 20H(2)O}(2) (2) were obtained from a simple reaction in aqueous solution without heating. Structural analyses revealed that complexes I and 2 feature a cage compound Sb-12} with an encapsulated CO2}/Ni-2} core, implying the structural diversity in the Sb-12} cage assemblies constructed from potassium antimonyl tartrate as the ligand in aqueous solution. The temperature-dependent magnetic susceptibilities indicated that there are weak ferromagnetic intermolecular or/and intramolecular interactions in 1 and strong ferromagnetic behavior in 2, owing to the strong spin-orbital coupling (1) and Jahn-Teller effect (2). (C) 2018 Elsevier Ltd. All rights reserved.