Fig. 2: 57Fe Mössbauer and EPR spectroscopic characterization of the super-oxidized Fe(VI, VII) nitrides (1, 2) and the rearranged Fe(V) imide (3).
From: The synthesis and characterization of an iron(VII) nitrido complex
a, A mixture of Fe(VI)N (1) and Fe(VII)N (2) trapped in frozen solution and studied by zero-field 57Fe Mössbauer spectroscopy. While the Fe(VI) nitride possesses an isomer shift of –0.60 mm s−1, the Fe(VII) nitride reveals an exceptional negative isomer shift of −0.72 mm s−1 within the Fe nitride series. b, Rearrangement of the Fe(VII) nitride (2) to yield the Fe(V) imide (3). c, The zero-field 57Fe Mössbauer spectrum after complete conversion of 2 to 3, with a less negative isomer shift of −0.16 mm s−1, typical for an Fe(V) imide. d–f, Formation, rearrangement and complete transformation of 2 to 3, followed by X-band EPR spectroscopy. The Fe(VII) possesses an S = 1/2 signal (g1 = 2.058, g2 = 1.998, g3 = 1.908) with a characteristic three-line nitrogen hyperfine coupling (A3 = 6.8 mT) that vanishes following the rearrangement. 57Fe Mössbauer spectra a–c were recorded at 77 K and EPR spectra d–f at 15 K. Black circles (top) and lines (bottom) represent the experimental data, whereas the coloured lines represent the best fit obtained.
