Au103(SR)45, Au104(SR)45, Au104(SR)46 and Au105(SR)46 nanoclusters.

High resolution ESI mass spectrometry of the “22 kDa” nanocluster reveals the presence of a mixture containing Au103(SR)45, Au104(SR)45, Au104(SR)46, and Au105(SR)46 nanoclusters, where R = –CH2CH2Ph. MALDI TOF MS data confirm the purity of the sample and a UV-vis spectrum shows minor features. Au102(SC6H5COOH)44, whose XRD crystal structure was recently reported, is not observed. This is due to ligand effects, because the 102:44 composition is produced using aromatic ligands. However, the 103-, 104- and 105-atom nanoclusters, protected by –SCH2CH2Ph and –SC6H13 ligands, are at or near 58 electron shell closing.