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.