Atomically Precise Palladium Nanoclusters with 21 and 38 Pd Atoms Protected by Phenylethanethiol
Senthil Kumar Eswaramoorthy, Amala Dass
Abstract
Monolayer thiolate-protected nanoclusters (MPCs) are extensively studied due to their distinctive properties. The atomic precision in MPCs, especially in gold MPCs, is determined through mass spectrometry, which leads to the accurate identification of metal-ligand composition. The total structure determination of gold and silver MPCs using ScXRD revolutionized the field by providing insights into the structural arrangement at an atomic level. The synthesis of atomically precise MPCs using other metals like palladium (Pd) to study and compare properties is tedious and complex. In one end, larger size monodisperse Pd nanoparticles (NPs) were synthesized and studied for various catalytic properties. Meanwhile, on the other end, a small-molecule tiara-like Pd–thiolate complex was reported. However, atomic precise Pd MPCs in the middle and its detailed studies are not yet explored. Here, we report the synthesis and identification of atomically precise phenylethanethiol-protected Pd21(SCH2CH2Ph)18 and Pd38(SCH2CH2Ph)21S2 Pd nanoclusters. The size distribution is confirmed using matrix-assisted laser desorption ionization mass spectra (MALDI-MS), and electrospray ionization mass spectrometry (ESI-MS) confirms the composition through the isotopically resolved peak. The X-ray photoelectron spectroscopy (XPS) spectra elucidate the cluster formation in smaller size.