Sc, Zr, Hf, and Mn Metal Nanoparticles: Reactive Starting Materials for Synthesis Near Room Temperature.

Zerovalent scandium, zirconium, hafnium, and manganese nanoparticles are prepared by reduction of ScCl 3 , ZrCl 4 , HfCl 4 , and MnCl 2 with lithium or sodium naphthalenide in a one-pot, liquid-phase synthesis. Small-sized monocrystalline nanoparticles are obtained with diameters of 2.4 ± 0.2 nm (Sc), 4.0 ± 0.9 nm (Zr), 8.0 ± 3.9 nm (Hf) and 2.4 ± 0.3 nm (Mn). Thereof, Zr(0) and Hf(0) nanoparticles with such size are shown for the first time. To probe the reactivity and reactions of the as-prepared Sc(0), Zr(0), Hf(0), and Mn(0) nanoparticles, they are exemplarily reacted in the liquid phase (e.g., THF, toluene, ionic liquids) with different sterically demanding, monodentate to multidentate ligands, mainly comprising O-H and N-H acidic alcohols and amines. These include isopropanol (HO i Pr), 1,1'-bi-2-naphthol (H 2 binol), N , N '-bis(salicylidene)ethylenediamine (H 2 salen), 2-mercaptopyridine (2-Hmpy), 2,6-diisopropylaniline (H 2 dipa), carbazole (Hcz), triphenylphosphane (PPh 3 ), N , N , N ', N '-tetramethylethylenediamine (tmeda), 2,2'-bipyridine (bipy), N , N '-diphenylformamidine (Hdpfa), N , N '-(2,6-diisopropylphenyl)-2,4-pentanediimine ((dipp) 2 nacnacH), 2,2'-dipydridylamine (Hdpa), and 2,6-bis(2-benzimidazolyl)pyridine (H 2 bbp). As a result, 22 new compounds are obtained, which frequently exhibit a metal center coordinated only by the sterically demanding ligand. Options and restrictions for the liquid-phase syntheses of novel coordination compounds using the oxidation of base-metal nanoparticles near room temperature are evaluated.