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Published on: August 12, 2019
Panchromatic Absorption and Oxidation of an Iron(II) Spin Crossover Complex
Johannes Moll1, Christoph Förster1, Alexandra König1
1Department of Chemistry, Johannes Gutenberg University, Duesbergweg 10-14, 55128 Mainz, Germany.
Abstract:
In order to expand and exploit the useful properties of d6-iron(II) and d5-iron(III) complexes in potential magnetic, photophysical, or magnetooptical applications, crucial ligand-controlled parameters are the ligand field strength in a given coordination mode and the availability of suitable metal and ligand frontier orbitals for charge-transfer processes. The push-pull ligand 2,6-diguanidylpyridine (dgpy) features low-energy π* orbitals at the pyridine site and strongly electron-donating guanidinyl donors combined with the ability to form six-membered chelate rings for optimal metal-ligand orbital overlap. The electronic ground states of the pseudo-octahedral d6- and d5-complexes -[Fe(dgpy)], -[Fe(dgpy)], and -[Fe(dgpy)] as well as their charge-transfer (CT) and metal-centered (MC) excited states are probed by variable temperature UV/vis absorption, NMR, EPR, and Mössbauer spectroscopy, magnetic susceptibility measurements at variable temperature as well as quantum chemical calculations.
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