Bis((dialkylamino)alkylselenolato)metal complexes as precursors for microwave-assisted synthesis of semiconductor metal selenide nanoparticles of zinc and cadmium in the ionic liquid [BMIm][ BF4]

• (Dialkylamino)alkylselenolates as new single-source precursors for ZnSe and CdSe-NPs.
• ZnSe- and CdSe-NPs were obtained by microwave irradiation of precursor/IL suspensions.
• Obtained particles were mostly spherical, crystalline and only slightly agglomerated.
• No further stabilizing agents needed and no formation of metal fluorides observed.
• For ZnSe the particle diameter was 4–7 nm, while for CdSe the diameter was 10–19 nm.

Based on (dimethylamino)ethyldiselenide, (diethylamino)ethyldiselenide and (dimethylamino)propyldiselenide six different bis(dialkylamino)alkylselenolates with zinc and cadmium were decomposed by microwave irradiation in the ionic liquid (IL) 1-butyl-3-methyl-imidazolium tetrafluoridoborate ([BMIm][BF4]) to give the respective metal selenide nanoparticles. In comparison to common methods like the hot injection method attention was paid how variations of the ligand system and different decomposition times affect the nanoparticle synthesis with respect to size, shape, crystallinity and crystal phase. The decomposition of the single-source zinc and cadmium precursors in the fluorous IL led mostly to spherical, crystalline and only slightly agglomerated nanoparticles. No formation of ZnF2 or CdF2 was observed which is different from the known dual-source synthesis. In case of the zinc precursors, hexagonal and cubic ZnSe with a particle diameter between 4–7 nm were obtained, whereas in case of the cadmium precursors hexagonal CdSe with an average particle diameter of 10–19 nm were prepared. An increase in decomposition time from 5 to 15 min at 250 °C mostly led to similar results concerning the particle size and crystal phase which is different from the hot injection method, thereby suggesting that the IL has a decisive role for nanocrystal growth and stabilization. No further stabilizing agents were necessary to reproducibly prepare ZnSe or CdSe particles with an average diameter below 10 or 20 nm, respectively. All dispersions of the metal selenide nanoparticles in [BMIm][BF4] were characterized by high resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray spectroscopy (EDX) and X-ray powder diffraction (PXRD).

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