Electronic Structure, Vibrational Spectra and Probing of Spin-states of Tetra-coordinated Iron(II) Porphyrins

06 May 2022, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

The nearly degenerate spin multiplets of the iron(II) porphyrins have endowed these biomacromolecules with potential for use in various applications such as, molecular spintronics, single molecule devices, and sensor technology. Achieving a definitive understanding of the spin crossover in these complexes is a challenging area to explore. In this work, we aim to provide a theoretical perspective of the magneto-structural correlations and their resulting spectroscopic signatures for a series of tetra-coordinated, square-planar iron(II) porphyrin and phthalocyanine derivatives. We systematically investigate the spin-state energies, vibrational, and pre-edge X-ray spectra of these complexes in three possible spin states (viz. low spin (S = 0), intermediate spin (S = 1) and high spin (S = 2)). Our calculations show that the triplet or intermediate spin state is the ground spin state for all the complexes. We also observe that the small structural difference in the dFe−N between the intermediate- and high-spin sate in these complexes can be captured using nuclear resonance vibrational spectra (NRVS). Furthermore, our results identify the position of the X-ray absorption (XAS) peaks as a signature of the underlying spin state.

Keywords

Porphyrin
XAS
NRVS
DFT

Supplementary materials

Title
Description
Actions
Title
Supporting Information
Description
Spin density and population analysis, vertical spin gap from different methods, computed IR and Raman spectra, contribution of the Fe motion to a vibrational mode, and transitions in the XAS spectra.
Actions

Comments

Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.