Room‐Temperature Oxidation of Thulium‐Metal Nanoparticles to the Thulium Oxocluster [Tm$_5$O(O$^i$Pr)$_{13}$]

Zerovalent thulium nanoparticles (2.2±0.3 nm in size) are used as the starting material to prepare single crystals of the thulium oxocluster [Tm$_5$O(O$^i$Pr)$_{13}$]. The reaction is performed by controlled oxidation of the Tm(0) nanoparticles at room temperature (25°C) in isopropanol. The pentanuclear oxocluster contains a non-charged molecular unit with a central Tm$_5$O core and five μ$_1$-, four μ$_2$-, and four μ$_3$-bridging (O$^i$Pr)$^−$ ligands. Single-crystal structure analysis (P2$_1$/n, a=1247.7(6), b=2146.2(15), c=2056.6(9) pm, $\beta$=93.23(1)°) and infrared spectroscopy confirm the oxidation of HO$^i$Pr with formation of H$_2$ and (O$^i$Pr)$^−$. Temperature-dependent measurements show antiferromagnetic coupling. Such a polynuclear [Ln$_5$O(O$^i$Pr)$_{13}$] oxocluster (Ln: lanthanide) is prepared with thulium-metal nanoparticles as a starting material for the first time and points to the suitability of reactive rare-earth metal nanoparticles as starting materials.