Synthesis of NiS and MnS Nanocrystals from the Molecular Precursors (TMEDA)M(SC{O}C6H5)2 (M = Ni, Mn)

The compounds (TMEDA)M(SC{O}C6H5)2 (M = Ni, 1; Mn, 2) have been synthesized and characterized by X-ray crystallography. Both of the monomeric molecular precursors have been used to make the corresponding monodispersed NiS (two different phases) and cubic phase MnS nanocrystals (NCs) under specific experimental conditions. Changing the surfactants yielded low-temperature rhombohedral β-NiS NCs with millerite structure in dodecanethiol and high-temperature hexagonal α-NiS NCs with NiAs-type structure in oleic acid, while monodispersed hexagonal shaped α-MnS NCs with rock-salt structure were obtained in the presence of a combination of oleylamine and dodecanethiol surfactants. The NCs have been characterized by X-ray powder diffraction patterns, transmission electron microscopy, selected area electron diffraction patterns, and energy-dispersive X-ray analysis. Preliminary magnetic measurements show that the two phases of NiS NCs exhibit weak magnetism and hysteresis.