When reacting the organic functionalized tin selenide clusters [(SnR ) Se Cl] (A, R =CMe CH C(O)Me) or [(SnR ) Se ] (B) with (SiMe ) Se and [Ag(PPh ) Cl] at -78 °C in CH Cl , a microcrystalline intermediate (compound 1) precipitates, which was investigated by magic angle spinning (MAS) NMR spectroscopy, powder X-ray diffraction (PXRD), energy dispersive X-ray (EDX) spectroscopy, and quantum chemistry calculations, to derive information about its composition and structure. Compound 1 re-dissolves under reorganization into the organo-functionalized Ag/Sn/Se cluster compound [Ag (μ -Se)(Ag Se ){(R Sn) Se } ] (2), or the mixed-valence cluster [(AgPPh ) (Sn Cl) Se {(R Sn ) Se } ] (3), depending on the presence or the exclusion of daylight, respectively. The addition of N H ⋅H O to a solution of 1 yields selectively [Ag (μ -Se)(Ag Se ){(R Sn) Se } ] (4, R =CMe CH C(N H )Me), the Ag/Sn/Se core of which is isomeric to that of 2. 2-4 were characterized by X-ray diffraction. NMR spectroscopic studies on solutions of 1 indicate the co-existence of different species.