Title

A High-pressure Iron K-edge X-ray Absorption Spectral Study of the Spin-state Crossover in Fe[HC(3,5-(CH₃)₂pz)₃]₂ I₂ and Fe[HC(3,5-(CH₃)₂pz)3]₂ (BF₄)₂

Abstract

The room temperature iron K-edge X-ray absorption near edge structure spectra of Fe[HC(3,5-(CH3)2pz)3]2 I2 and Fe[HC(3,5-(CH3)2pz)3]2 (BF4)2 have been measured between ambient and 88 and 94 kbar, respectively, in an opposed diamond anvil cell. The iron(II) in Fe[HC(3,5-(CH3)2pz)3] 2I 2undergoes the expected gradual spin-state crossover from the high-spin state to the low-spin state with increasing pressure. In contrast, the iron(II) in Fe[HC(3,5-(CH3)2pz)3] 2(BF4)2 remains high-spin between ambient and 78 kbar and is only transformed to the low-spin state at an applied pressure of between 78 and 94 kbar. No visible change is observed in the preedge peak in the spectra of Fe[HC(3,5-(CH3)2pz)3] 2I2 with increasing pressure, whereas the preedge peak in the spectra of Fe[HC(3,5-(CH3)2pz)3] 2(BF4)2 changes as expected for a high-spin to low-spin crossover with increasing pressure. The difference in the spin-state crossover behavior of these two complexes is likely related to the unusual behavior of Fe[HC(3,5-(CH3)2pz)3]2 (BF4)2 upon cooling.

Department(s)

Chemistry

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2003 American Chemical Society (ACS), All rights reserved.


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