Models for Cytochromes <i>c′</i>: Observation of an Extremely Labile Spin State in Monoimidazole Complexes of Saddle‐Shaped Iron(III) Porphyrinates

Abstract

Saddle in a spin: The saddle-shaped octaethyltetraphenylporphyrin–imidazole complex [FeIII(oetpp)(HIm)]+ adopts an essentially pure intermediate-spin state between 298 and 173 K in CD2Cl2 solution, the conditions under which the NMR spectra are recorded. This complex has shown, however, a novel spin transition from S=3/2 to S=5/2 and S=1/2 below 70 K. Thus, the complex exists as an equilibrium mixture of three spin isomers at 4 K. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.