A new type of heteropolyanion containing mixed-valence antimony, [(Sb4Sb2Mo18O73)-Sb-V(H2O)(2)](12-) (1a), and its four derivatives, {M(H(2)o)(2)[(Sb4Sb2Mo18O73)-Sb-V-Mo-III(H2O)(2)](2)}(22-) (M = Mn-II, Fe-II, Cu-II, or Co-II) (2a- 5a), have been isolated as ammonium salt, and their structures were determined by single-crystal X-ray diffraction. The framework of the polyanion la displays a curious asymmetric structure, and there exist six types of Sb coordination environments and seven types of {MoO6} octahedra. The title compounds were also characterized by elemental analyses, IR, UV-vis, Raman spectra, and cyclic voltammogramms.