Functionalised Silver Chalcogenide Clusters

Eight new silver chalcogenide clusters with different functional groups in the ligand shell were synthesised and characterised by single-crystal X-ray diffraction. The optical properties of the isostructural clusters [Ag-6(S-C6H4-CN)(6)(PPh3)(6)] (1) and [Ag-6(S-C6H4-NO2) 6(PPh3) 6] (2) are described and compared. In addition, the reactivity of 1 towards metal salts and Lewis acids was investigated, which led to the compounds [Ag-6(S-C6H4-CN)(6)(PPh3)(5)] (3) and [Ag14S(S-C6H4-CN)(12)(PPh3)(8)][FeCl2(thf)(4)](3) (4). The sulfur-functionalised cluster [Ag14S(S-C6H4-NCS)(12)(PPh3)(8)] (5) has prospects for further reactions and for the immobilisation on gold surfaces. The reactions of silver carboxylates with O,S-bis(trimethylsilyl)-4-hydroxythiophenol and bis(trimethylsilyl) chalcogenides in the presence of tertiary phosphanes lead to the formation of the clusters [Ag23S2(S-C6H4-OSiMe3)(15)(S-C6H4-OH)(3)(PPh3)(8)] (6) and [Ag40Se4(S-C6H4-OSiMe3)(32)(PPh3)(8)] (7). Compound 6 can be regarded as a dimer of the described Ag14-clusters in 4 and 5, whereas the inorganic core of cluster 7 has an unusual curved structural motif. The reaction of AgOAc with 4-hydroxothiophenol in the presence of triethylphosphane leads to the assembly of a three dimensional network of [Ag-8(S-C6H4-OH)(6)(PEt3)(8)](OAc)(2) (8) in the crystal structure. A solution of 8 was investigated by ESI mass spectrometry, which resulted in the detection of a series of polynuclear silver thiolates with the general composition [Ag-n(S-C6H4-OH)(n-1)(PEt3)(2)](+).