Syntheses and Crystal Structures of [Ag123S35(StBu)50] and [Ag344S124(StBu)96]

摘要

We have recently reported the syntheses of metal-rich silver chalcogenide clusters.[1] Examples of these are [Ag70S16(SPh)34(PhCO2)4(triphos)4], [Ag70S20(SPh)28(dppm)20](CF3CO2)2, [Ag188S94(PnPr3)20], and [Ag262S100(StBu)62(dppb)6] (triphos=1,1,1-tris(diphenylphosphinomethyl)ethane, dppm=bis(diphenylphosphino)methane, dppb=1,4-bis(diphenylphosphino)butane). These compounds are formed in high yield by the reaction of silylated sulfur compounds with silver salts. The reaction of AgCF3CO2 with PnPr3 and S(SiMe3)2 yields [Ag188S94(PnPr3)20], whereas [Ag262S100(StBu)62(dppb)6] is formed from the reaction of AgPhCO2 and dppb with a mixture of S(tBu)SiMe3 and S(SiMe3)2 in THF.[1] Both compounds contain unusual sections of the structure of binary silver sulfide;[2]-[4] these Ag-S cluster cores are surrounded by tertiary phosphines or StBu groups. Such compounds can be regarded as intermediary stages in the formation of Ag2S, in which phosphine and StBu ligands have inhibited further growth of the cluster core towards crystalline Ag2S. A striking feature of these structures is the tendency to disorder shown by the anions and cations. In this respect the molecules already possess to a large extent the properties of the binary Ag2S phase.[2]-[4] [Ag188S94(PnPr3)20] is a spheroidal molecule which has a Ag2S core with a diameter of 1.9 nm. In [Ag262S100(StBu)62(dppb)6] the molecules have the form of oblate ellipsoids, in which the Ag-S cluster has a maximum diameter of 2.6 nm. In the course of studying size-dependent properties, such as the conductivity of electrons and Ag+ ions, which could also possibly be studied in single molecules, we have attempted to synthesize further examples of this class of molecules.