Stable Anilinyl Radicals Coordinated to Nickel: X‐ray Crystal Structure and Characterization. Issue 49 (4th November 2013)

• Record Type: Journal Article
• Authors: Kochem, Amélie; Gellon, Gisèle; Leconte, Nicolas; Baptiste, Benoit; Philouze, Christian; Jarjayes, Olivier; Orio, Maylis; Thomas, Fabrice
• Is Part Of: Chemistry. Volume 19:Issue 49(2013)
• Page Start: 16707
• Page End: 16721
• Publication Date: 2013-11-04
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201303228
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Two anilinosalen and a mixed phenol‐anilinosalen ligands involving sterically hindered anilines moieties were synthesized. Their nickel(II) complexes <bold>1</bold>, <bold>2</bold>, and <bold>3</bold> were prepared and characterized. They could be readily one‐electron oxidized (<italic>E</italic><sub>1/2</sub>=−0.30, −0.26 and 0.10 V vs. Fc<sup>+</sup>/Fc, respectively) into anilinyl radicals species [<bold>1]<sup>+</sup></bold>, [<bold>2]<sup>+</sup></bold>, and [<bold>3]<sup>+</sup></bold>, respectively. The radical complexes are extremely stable and were isolated as single crystals. X‐ray crystallographic structures reveal that the changes in bond length resulting from oxidation do not exceed 0.02 Å within the ligand framework in the symmetrical [<bold>1]<sup>+</sup></bold> and [<bold>2]<sup>+</sup></bold>. No quinoid bond pattern was present. In contrast, larger structural rearrangements were evidenced for the unsymmetrical [<bold>3]<sup>+</sup></bold>, with shortening of one C<sub>ortho</sub>C<sub>meta</sub> bond. Radical species [<bold>1]<sup>+</sup></bold> and [<bold>2]<sup>+</sup></bold> exhibit a strong absorption band at around 6000 cm<sup>−1</sup> (class III mixed valence compounds). This band is significantly less intense than [<bold>3]<sup>+</sup></bold>, consistent with a rather localized anilinyl radical character, and thus a classification of this species as class II mixed‐valence compound. Magnetic and electronic properties, as well as structural parameters, have been computed by DFT methods.</p> </abstract>