Asymmetrically substituted triazenes as poor electron donor ligands in the precursor chemistry of iron(ii) for iron-based metallic and intermetallic nanocrystals

Abstract

Triazene ligands are introduced, for the first time, in the precursor chemistry for their ability to afford oxygen-free molecular precursors of Fe⁰ nanoparticles. For this purpose, we synthesized new asymmetric triazene ligands t-BuNN-NHR (R = Et, i-Pr, n-Bu) featuring different alkyl substituents at 1,3-N centers, as well as a symmetric ligand t-BuNN-NHt-Bu and used them to develop novel heteroleptic monomeric Fe^II triazenide derivatives [Fe(t-BuN₃R)₂(TMEDA)] (where TMEDA = tetramethylethylenediamine). A range of physico-chemical studies such as FT-IR, TG-DTA, ¹H & ¹³C NMR, mass spectrometry, single crystal X-ray structure analysis, cyclic voltammetry and Mössbauer spectroscopy were used to characterize these newly synthesized ligands and Fe^II derivatives. One representative derivative [Fe(t-BuN₃Et)₂(TMEDA)] was evaluated as a precursor for the synthesis of metallic Fe⁰ and intermetallic Al₁₃Fe₄ nanoparticles by the chemical solution deposition method.