Probing the spin states of tetra-coordinated iron(II) porphyrins by their vibrational and pre K-edge x-ray absorption spectra

• Tetra-coordinated iron(II) porphyrins are observed in triplet (intermediate spin, IS) ground state with low-lying quintet (high spin, HS) and singlet (low spin, LS) excited states. It is well known in the literature that the d(Fe_N) bond distances are dependent on the spin state such that the d(Fe_N) distances are larger for HS compared to the LS/IS states. This implies the existence of strong magneto-structural correlations. Herein, the possibility to obtain the spin-state information for a series of tetra-coordinated square planar iron(II) porphyrin complexes have been explored by exploiting the magneto-structural correlations obtained from first principle calculations. The spin-state dependent nature of the chemical bonds and spin polarization on the N-atoms play a crucial role in the vibrational dynamics of the central Fe-atom. Theoretical nuclear resonance vibrational spectroscopy (NRVS) is adopted to investigate the vibrational dynamics and the Fe-atom associated spectral peaks and their spin-dependent features. We find that NRVS studies along with iron pre-K-edge x-ray absorption analysis convincingly provide the information on the spin state, which could be utilized to identify the spin states without adopting any magnetic probes.

Ämnesord

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

Nyckelord

DFT

iron porphyrin

NRVS

XAS

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