Au21S(SAdm)15: Crystal Structure, Mass Spectrometry, Optical Spectroscopy, and First-Principles Theoretical Analysis

Here we report X-ray crystal structure, spectroscopic and theoretical characterization of Au21S(SAdm)15 (SAdm = adamantanethiol). Single-crystal X-ray diffraction shows that the Au21S(SAdm)15 nanomolecule exhibits a Au12 cuboctahedral core missing one vertex surrounded by a single μ3 sulfur atom (sulfide), five bridging thiols, two additional Au atoms, one monomeric Au(SR)2, and two trimeric Au3(SR)4 staples, with the two trimeric staples being linked through a Au2(SR) unit with a thiolate ligand in μ4 coordination. Compositional, electronic, optical, and structural features of this compound are clarified via nanoelectrospray ionization mass spectrometry (nESI-MS), matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS), low-temperature UV−vis spectroscopy, and first-principles analysis.