The discovery of fullerenes [1] has induced considerable interest in spherical molecular clusters, see for example Refs. [2][3][4][5]. Among fullerene-like molecules, spherical watersoluble metal-oxide-based nanocapsules of the type {(M VI )M VI 5 } 12 (linker) 30 (M = Mo or W), belonging to the family of Keplerates, [5,6] show quite attractive features in the context of nano-and materials science, especially in confined scenarios. [7][8][9] Correspondingly, they have been the focus of reviews [10,11] and highlights, including some in recent textbooks.[ [10,11] In case of the Mo 132 -type cluster, the interiors of the capsules can be fine-tuned by changing the internal ligands coordinated to the {Mo V 2 O 4 } linkers. Most importantly, the above-mentioned Keplerates can interact specifically with their environment. [10][11][12] Especially the crown ethertype {Mo 9 O 9 } pores can react through hydrogen bonding with organic cations (like the guanidinium, amidinium, or protonated urea type), [13] as well as with hydrated metal ions, whereby all act as plugs leading to the closing of the capsules.[ . The important result is that the pore sizes and reactivities/flexibilities as well as the interior capsule properties-also in context of an increase in the internal shell polarizability-are changed by substituting 60 oxide atoms of the known Keplerate containing {Mo V 2 O 4 } linkers by 60 sulfide atoms; this has, for example, consequences for ligand and cation uptake/release processes [17] as well of course as for the structure of encapsulated species.The synthesis process follows that of previously reported mixed metal Keplerates where the basic {(M VI )M VI 5 }-type units (M = Mo, W) form in solution according to the principles of "Constitutional Dynamic Chemistry" of Lehn [18] while finally 12 of the units get appropriately linked when cations, like {Mo 2 O 4 (aq)} 2+ , [19] VO(aq) 2+ , [15a] or Fe(aq) 3+ [15b] are added to a dynamic library of molybdates and tungstates. In the present case, an aqueous solution of the new dinuclear linker {Mo -allowed to obtain the watersoluble Keplerate-type compound 1 (which allows future reactivity studies in solution) as starting material for the less soluble compound 2 [ *** ] which was isolated by "recrystallization" of the nonrecrystallized 1 in the presence of cobalt (II) ions to get suitable crystals (for details see the Experimental Section). Whereas compound 1 could be only partially characterized because of the poor crystal quality (for the "approximate" formula see Experimental Section), this was not the case for compound 2 which is the focus of our present work. Compound 2, which crystallizes in the space group Immm, was fully characterized by elemental analysis,
