RESUMO
Dinuclear transition metal complexes with direct metal-metal interactions have the potential to generate unique reactivities and properties. Using asymmetric triazine ligands HN3tBuR (R = Et, iPr, nBu) featuring different alkyl substituents at 1,3-N centers, we report here the first rational synthesis of 'tetragonal lantern' type Fe(II) triazenides [Fe2(N3tBuR)4] [R = Et (1), iPr (2), nBu (3)] having an exceptionally short Fe-Fe distance (2.167-2.174 Å). Unlike the previously reported lantern structures with related amidinate or guanidinate ligands, highly air-sensitive 1-3 show a lower spin ground state, as indicated by Mössbauer, 1H NMR and DFT studies.
RESUMO
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-BuN[double bond, length as m-dash]N-NHR (R = Et, i-Pr, n-Bu) featuring different alkyl substituents at 1,3-N centers, as well as a symmetric ligand t-BuN[double bond, length as m-dash]N-NHt-Bu and used them to develop novel heteroleptic monomeric FeII 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 FeII 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.