Valence self-regulation of sulfur in nanoclusters

The valence self-regulation of sulfur from the "-2" valence state in thiols to the "-1" valence state in hydroxylated thiolates has been accomplished using the PtAg nanocluster as a platform-the first time that the "-1" valent sulfur has been detected as S. Two previously unknown nanoclusters, PtAg(SR) and PtAg(SR)(HO-SR) (where SR represents 2-adamantanethiol), have been synthesized and characterized-in the latter nanocluster, the presence of hydroxyl induces the valence regulation of two special S atoms from "-2" (in SR) to "-1" valence state in the HO-S(Ag)R. Because of the contrasting nature of the capping ligands in these two nanoclusters [i.e., only SR in PtAg(SR) or both SR- and HO-SR- in PtAg(SR)(HO-SR)], they exhibit differing shell architectures, even though their cores (PtAg) are in the same icosahedral configuration. Single-crystal x-ray diffraction analysis revealed their 1:1 cocrystallization, and mass spectrometry verified the presence of hydroxyls on PtAg(SR)(HO-SR).