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 Pt(1)Ag(28) nanocluster as a platform—the first time that the “−1” valent sulfur has been detected as S(−1). Two previously unknown nanoclusters, Pt(1)Ag(28)(SR)(20) and Pt(1)Ag(28)(SR)(18)(HO-SR)(2) (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 Pt(1)Ag(28)(SR)(20) or both SR- and HO-SR- in Pt(1)Ag(28)(SR)(18)(HO-SR)(2)], they exhibit differing shell architectures, even though their cores (Pt(1)Ag(12)) 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 Pt(1)Ag(28)(SR)(18)(HO-SR)(2).