Monitoring the growth of Ag-S clusters through crystallization of intermediate clusters.

We report a series of Ag-S nanoscale clusters in an attempt to understand the growth process of Ag2S clusters. UV-vis monitoring and crystallization at different stages of the reaction map out the cluster growth steps from Ag31S3(StBu)17(tfa)8(MeCN)4 (tfa = trifluoroacetate), to Ag45S7(StBu)24(tfa)7 to [Ag62S13(StBu)32(tfa)2](tfa)2, showing sequential eye-catching color changes. The cluster growth is associated with the in situ generation of S2-, which comes from the C-S bond cleavage of tert-butyl thiolate.