Formation and Structural Diversity of Organo-Functionalized Tin-Silver Selenide Clusters

When reacting the organic functionalized tin selenide clusters [(SnR1)(3)Se4Cl] (A, R-1=CMe2CH2C(O)Me) or [(SnR1)(4)Se-6] (B) with (SiMe3)(2)Se and [Ag(PPh3)(3)Cl] at -78 degrees C in CH2Cl2, 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-6((6)-Se)(Ag8Se12){((RSn)-Sn-1)(2)Se-2}(6)] (2), or the mixed-valence cluster [(AgPPh3)(2)((SnCl)-Cl-II)(2)Se-2{((RSnIV)-Sn-1)(2)Se-2}(2)] (3), depending on the presence or the exclusion of daylight, respectively. The addition of N2H4H2O to a solution of 1 yields selectively [Ag-7((7)-Se)(Ag7Se12){((RSn)-Sn-2)(2)Se-2}(6)] (4, R-2=CMe2CH2C(N2H2)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.