Iron 10‐Thiacorroles: Bioinspired Iron(III) Complexes with an Intermediate Spin (S=3/2) Ground State. Issue 10 (29th January 2014)

• Record Type: Journal Article
• Authors: Sakow, Dimitri; Baabe, Dirk; Böker, Birte; Burghaus, Olaf; Funk, Markus; Kleeberg, Christian; Menzel, Dirk; Pietzonka, Clemens; Bröring, Martin
• Is Part Of: Chemistry. Volume 20:Issue 10(2014)
• Page Start: 2913
• Page End: 2924
• Publication Date: 2014-01-29
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201303786
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>A first systematic study upon the preparation and exploration of a series of iron 10‐thiacorroles with simple halogenido (F, Cl, Br, I), pseudo‐halogenido (N<sub>3</sub>, I<sub>3</sub>) and solvent‐derived axial ligands (DMSO, pyridine) is reported. The compounds were prepared from the free‐base octaethyl‐10‐thiacorrole by iron insertion and subsequent ligand‐exchange reactions. The small N<sub>4</sub> cavity of the ring‐contracted porphyrinoid results in an intermediate spin (i.s., <italic>S</italic>=3/2) state as the ground state for the iron(III) ion. In most of the investigated cases, the i.s. state is found unperturbed and independent of temperature, as determined by a combination of X‐ray crystallography and magnetometry with <sup>1</sup>H NMR‐, EPR‐, and Mössbauer spectroscopy. Two exceptions were found. The fluorido iron(III) complex is inhomogenous in the solid and contains a thermal i.s. (<italic>S</italic>=3/2)→high spin (h.s., <italic>S</italic>=5/2) crossover fraction. On the other side, the cationic bis(pyridine) complex resides in the expected low spin (l.s., <italic>S</italic>=1/2) state. Chemically, the iron 10‐thiacorroles differ from the iron porphyrins mainly by weaker axial ligand binding and by a cathodic shift of the redox potentials. These features make the 10‐thiacorroles interesting ligands for future research on biomimetic catalysts and model systems for unusual heme protein active sites.</p> </abstract>