Spin Equilibrium in Iron(II) Poly(1-pyrazolyl)borate Complexes: Low-temperature and High-pressure Mössbauer Spectral Studies
A high-pressure and low-temperature applied field Mössbauer effect study has revealed that Fe[HB(pz)3]2, which contains low-spin iron(II) from room temperature down to 4.2 K, may be converted in part to high-spin iron(II) at pressures above ca. 40 kbar. In contrast, Fe[HB(3,4,5-(CH3)3pz)3]2, which our studies reveal remains high-spin down to 1.7 K, may be converted to the low-spin state at high pressure. Because of the weaker crystal field potential of the substituted ligand in this compound, a pressure of ca. 55 kbar is required to make the high-spin 5T2g state and low-spin 1A1g state equivalent in energy at room temperature. In Fe[HB(3,5-(CH3)2pz)3]2 the intermediate crystal field potential yields a spin crossover at low temperature (ca. 195 K), and in this case only 4 kbar is required to make the two spin states equivalent in energy at room temperature. All three compounds show a linear dependence of the isomer shift and quadrupole interaction upon the applied pressure, and the spin-state transitions are completely reversible. © 1987 American Chemical Society.
G. J. Long and B. B. Hutchinson, "Spin Equilibrium in Iron(II) Poly(1-pyrazolyl)borate Complexes: Low-temperature and High-pressure Mössbauer Spectral Studies," Inorganic Chemistry, American Chemical Society (ACS), Jan 1987.
The definitive version is available at https://doi.org/10.1021/ic00251a023
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© 1987 American Chemical Society (ACS), All rights reserved.