Nanosized Gadolinium and Uranium—Two Representatives of High-Reactivity Lanthanide and Actinide Metal Nanoparticles

[Image: see text] Gadolinium (Gd(0)) and uranium (U(0)) nanoparticles are prepared via lithium naphthalenide ([LiNaph])-driven reduction in tetrahydrofuran (THF) using GdCl(3) and UCl(4), respectively, as low-cost starting materials. The as-prepared Gd(0) and U(0) suspensions are colloidally stable and contain metal nanoparticles with diameters of 2.5 ± 0.7 nm (Gd(0)) and 2.0 ± 0.5 nm (U(0)). Whereas THF suspensions are chemically stable under inert conditions (Ar and vacuum), nanoparticulate powder samples show high reactivity in contact with, for example, oxygen, moisture, alcohols, or halogens. Such small and highly reactive Gd(0) and U(0) nanoparticles are first prepared via a dependable liquid-phase synthesis and stand as representatives for further nanosized lanthanides and actinides.