Combined, Modulation Enhanced X-ray Powder Diffraction and Raman Spectroscopic Study of Structural Transitions in the Spin Crossover Material [Fe(Htrz)₂(trz)](BF₄)

Abstract

The structure of [Fe(Htrz) 2 (trz)]BF 4 (1, Htrz )1,2,4-4-H-triazole, trz ) 1,2,4-triazolate) at the low-spin (LS) and high-spin (HS) states and structural transitions between the two states were investigated by in situ highresolution synchrotron X-ray powder diffraction (XRPD) combined with Raman spectroscopy using a modulation-enhanced technique. The crystal structures of the LS and HS states were determined. A 1D chain structure of 1 at both LS and HS states was proven, and the lattice expansion upon LS-HS transition was mainly caused by the elongation of the chain. The differences in the behavior of the spin transition observed by XRPD and Raman spectroscopy were explained by the local sensitivity of the two different techniques and also by the spatial propagation of spin crossover phase transition within the crystallite and the body of the grain. Moreover, we demonstrated that the two-dimensional correlation analyses facilitate (i) understanding the data obtained by combined techniques, (ii) clarifying correlation between the signals gained by the different probes, and (iii) extracting information on temporal evolution of transformation processes.

Spin‐Crossover Nano‐ and Micrometric Rod‐Shaped Particles Synthesized in Homogeneous Acid Media

“…These Raman spectra compare well with those reported previously. [21,22] In the region of the spectra considered, only the spectral feature at ca. 1300 cm -1 can be used to distinguish the two compounds, namely the double-band character originating from the presence of the two different trz and Htrz ligands.…”

Time Resolved Operando X-ray Techniques in Catalysis, a Case Study: CO Oxidation by O2 over Pt Surfaces and Alumina Supported Pt Catalysts

“…As such, in recent years, the MES approach has started to be adopted by the X-ray community that studies a wide range of materials that includes catalysts. Since its first application in considering the dynamic responses of Rh and Pd catalysts under modulated feed conditions using dispersive XAFS [190], it has subsequently been utilized to enhance the ability of X-ray scattering techniques to see into dynamic catalyst behavior [191][192][193][194][195][196][197][198][199][200].…”

Control of Spin-Crossover Phenomena in One-Dimensional Triazole-Coordinated Iron(II) Complexes by Means of Functional Counter Ions

“…This measurement is a useful tool to reveal the local structure around iron(II) ions in [Fe(II)(R-trz) 3 ]Anion·xH 2 O; however, the crystal structure has become clearer in recent studies [12,46,47].…”