A recently discovered series of quaternary compounds of the general type [K-m(ROH)(n)][MxSnySet] (R = H, Me), containing ternary anions with [SnSe4](4-)-coordinated transition metal centers (M = Co, Mn, Zn, Cd, Hg) has now been extended by the synthesis and characterization of the two ortho-thiostannate-coordinated species, [Na-10(H2O)(32)][M5Sn(mu(3)-S)(4)(SnS4)(4)]center dot 2H(2)O (M = Zn (1), Co (2)). The central structural motifs of compounds 1 and anions, being the first T3-type supertetrahedral ternary anions reported are highly charged [M5Sn(mu(3)-S)(4)(SnS4)(4)](10-) to date. The exposure of single crystals of 2 to a dynamic vacuum for several hours resulted in the reversible formation of a partially dehydrated, but still monocrystalline material of the composition [Na-10(H2O)(6)](Co5Sn(mu(3)-S)(4)-(SnS4)(4)] (3). The loss of 28 of the 34 water molecules only slightly affects the internal structure of the ternary anion in 3 and leads to a significant compacting of the crystal structure with closer linkage of the [Co5Sn5S20](10) cluster units via the Na+ cations. Magnetic measurements on 3 show that the ground state of the Co/Sn/S cluster is S = 1/2, indicating a significant antiferromagnetic coupling between the Cc centers, which has also been rationalized by DFT investigations of the electronic situation in the ternary subunits of 1-3.