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Soluble platinum nanoparticles (Pt NPs) ligated by two different long-chain N-heterocyclic carbenes (LC-IPr and LC-IMe) were synthesized and fully characterized by TEM, high-resolution TEM, wide-angle X-ray scattering (WAXS), X-ray photoelectron spectroscopy (XPS), and solution NMR. The surface chemistry of these NPs (Pt@LC-IPr and Pt@LC-IMe) was investigated by FT-IR and solid state NMR using CO as a probe molecule. A clear influence of the bulkiness of the N-substituents on the size, surface state, and catalytic activity of these Pt NPs was observed. While Pt@LC-IMe showed no activity in the hydroboration of phenylacetylene, Pt@LC-IPr revealed good selectivity for the trans-isomer, which may be supported by a homogeneous species. This is the first example of hydroboration of acetylenes catalyzed by non-supported Pt NPs. [ABSTRACT FROM AUTHOR]

NHC ‐ ligated Pt nanoparticles were studied with regards to steric bulk of the ligands and their influence on NP size and catalytic properties. Bulky aryl groups at the N ‐ atoms gave small NPs of roughly 65 atoms, whereas small methyl groups gave larger NPs of around 260 atoms both with high ligand coverage, 12 and 70 ligands, respectively. Undecyl chains on the NHC ligands make the nanoparticles highly soluble and allowed for their use as catalysts in solution. Hydroboration of alkynes was observed for the first time with soluble NPs, but surprisingly only the bulky ‐ ligand ‐ containing Pt NPs were active. More information can be found in the Full Paper by F. Glorius, B. Chaudret and P. W. N. M. van Leeuwen et al. on page 12779. [ABSTRACT FROM AUTHOR]