Monolanthanum tripotassium tetra­hydrogen deca­molybdodicobaltate(III) trideca­hydrate

The title compound, K(3)La[H(4)Mo(10)Co(2)O(38)].13H(2)O, is an optically active chiral polyoxometalate (POM) which contains an anion with ideal point symmetry D2 (222). The crystals containing one of the enanti­omer pairs in the POM were resolved at pH 2.5. The factor that governs the formation of the compound is the pH condition of the mother liquor. The racemate salt, K(6)[H(4)Mo(10)Co(2)O(38)]·7H(2)O, is obtained at pH 6.5 [Nolan et al. (1998 ▶). Aust. J. Chem. 51. 825–834]. Two non-acidic H atoms in the POM form intra­molecular hydrogen bonds and the remaining two H atoms form hydrogen bonds with two water mol­ecules. The POMs are connected by three K(+) ions. The La(3+) ion is coordinated by three O atoms of the POM and six water molecues with distances in the range 2.516 (5)–2.589 (5) Å.