Synthesis of ternary sulfide nanomaterials using dithiocarbamate complexes as single source precursors

Abstract

We report the use of cheap, readily accessible and easy to handle di-isobutyl-dithiocarbamate complexes, [M(S2CNiBu2)n], as single source precursors (SSPs) to ternary sulfides of iron-nickel, iron-copper and nickel-cobalt. Varying decomposition temperature and precursor concentrations has a significant effect on both the phase and size of the nanomaterials, and in some instances meta-stable phases are accessible. Decomposition of [Fe(S2CNiBu2)3]/[Ni(S2CNiBu2)2] at ca. 210-230 °C affords metastable FeNi2S4 (violarite) nanoparticles, while at higher temperatures the thermodynamic product (Fe,Ni)9S8 (pentlandite) results. Addition of tetra-isobutyl-thiuram disulfide to the decomposition mixture can significantly affect the nature of the product at any particular temperature-concentration, being attributed to suppression of the intramolecular Fe(iii) to Fe(ii) reduction. Attempts to replicate this simple approach to ternary metal sulfides of iron-indium and iron-zinc were unsuccessful, mixtures of binary metal sulfides resulting. Oleylamine is non-innocent in these transformations, and we propose that SSP decomposition occurs via primary-secondary backbone amide-exchange with primary dithiocarbamate complexes, [M(S2CNHoleyl)n], being the active decomposition precursors.