High pressure and very low temperature effects on the crystal structures of some iron(II) complexes

Spin crossover in[MnIII(pyrol)3tren]probed by high-pressure and low-temperature x-ray diffraction

“…According to the standard deviation on pressure measurements the apparent accident at 0.5 GPa cannot be attributed to any transition, moreover a careful examination of the MnN6 core at higher pressure clearly stand for the persistence of the HS state. The fall observed at 1.50 GPa reflects the amorphization of the sample that starts at this pressure and is effective at higher pressure as already observed for molecular materials 9 .…”

“…For example, up to now (CSD search, December 2004), only 81 crystal structures determined at high pressure are reported in the Cambridge Structural Data Base which contains more than 320000 molecular crystal structures. The high pressure structural properties of only three SCO systems have been reported so far and all concern mononuclear complexes of iron(II) ions in octahedral surroundings 8,9 .…”

Pressure-induced two-step spin transition with structural symmetry breaking: X-ray diffraction, magnetic, and Raman studies

“…25 Indeed, the majority of high-pressure investigations involving SCO systems have used spectroscopic techniques or magnetic studies to characterize the effect of applied pressure on the spin transition. 26 Very few studies to date have used diffraction techniques to explore the relationship between structure and properties of SCO materials under pressure, [27][28][29][30] but such investigations are essential to establishing the driving forces behind the pressure-induced spin transition, as well as to thorough investigation of more complex phenomena such as stepped transitions.…”

Bulk spin-crossover in the complex [FeL(NCS)2] of a tris(pyridyl)ethane-derived N4-ligand—a temperature-dependent crystallographic study

“…To monitor the temperaturedependent changes, the Fe-N bond-lengths and their average d (Fe-N) were determined (see Table 2). Molecular distortion was evaluated using two established parameters: Σ is the sum of the deviation of all cis-angles θ i from 90°in a distorted octa- 25 This parameter is readily obtainable, but invariant to changes in bond lengths. A more sophisticated approach is the application of continuous symmetry measures (CSM) that quantify "the minimal distance movement that the points of an object have to undergo in order to be transformed into a shape of the desired symmetry".…”