Executive Summary : | Atomically precise metal clusters are new generation molecular materials with defined molecular formulas and solvable crystal structures. They serve as excellent model systems for understanding reaction mechanisms and nano-catalysis. However, due to ligand passivation, partial or complete ligand removal is required during catalyst preparation, resulting in the loss of the original cluster structure. To address this issue, hydride-rich clusters with catalytic H- transfer sites will be created and used as hydrogen reservoirs without destroying the molecule. These clusters will be synthesized and characterized using UV-vis absorption, photoluminescence, FT-IR, NMR spectroscopy, and ESI MS. Various phosphine ligands and SPhCl2, tert-butyl thiolate, 2,4-dimethylbenzenethiol, and phenylethane thiol will be used for synthesis. Sodium borohydride, 9-Borabicyclo[3.3.1]nonane, and sodium cyanoborohydride will be used to control the number of H- incorporation on the cluster surface. Cu and Cu containing alloy clusters will be synthesized using (PPh3)4CuBH4 and Stryker's reagent Cu6H6(PPh3)6 as Cu source and reducing agent. Temperature-dependent controlled release of hydride as hydrogen and related thermodynamics will be studied for applying the clusters as variable temperature hydrogen reservoirs. Higher H-containing clusters will be used to transfer H- to unsaturated organic compounds for catalytic hydrogenation. Hydride-rich thiolated, phosphine, or mixed ligand protected clusters will be used as catalysts for various organic reactions, allowing the catalyst to be recycled multiple times. |