All-aromatic, nanometer-scale, gold-cluster thiolate complexes.

We report a method to generate and isolate 22 and 29 kDa core mass gold:benzenethiolate monolayer-protected cluster (MPC) molecules and a subsequent reaction to yield [(octyl)4N]2[Au44(SC6H5)28] (8.7 kDa core) clusters from these materials. Characterization methods for these 1.0-1.7 nm molecules include vibrational, electronic, 1H NMR, and mass spectrometry, as well as powder X-ray diffraction. The clusters are anionic and charge balanced by tetraoctylammonium. They possess size-dependent optical absorbance bands consistent with size-quantized gold cores and are susceptible to electrochemical degradation in polar organic solvents. To our knowledge this is the first report of all arylthiolate gold MPC molecules, and they represent ideal materials for crystallization and total structural characterization.