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Stable Anilinyl Radicals Coordinated to Nickel: X‐ray Crystal Structure and Characterization
Author(s) -
Kochem Amélie,
Gellon Gisèle,
Leconte Nicolas,
Baptiste Benoit,
Philouze Christian,
Jarjayes Olivier,
Orio Maylis,
Thomas Fabrice
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201303228
Subject(s) - radical , chemistry , nickel , crystallography , steric effects , valence (chemistry) , crystal structure , electronic structure , ligand (biochemistry) , photochemistry , stereochemistry , computational chemistry , organic chemistry , biochemistry , receptor
Two anilinosalen and a mixed phenol‐anilinosalen ligands involving sterically hindered anilines moieties were synthesized. Their nickel(II) complexes 1 , 2 , and 3 were prepared and characterized. They could be readily one‐electron oxidized ( E 1/2 =−0.30, −0.26 and 0.10 V vs. Fc + /Fc, respectively) into anilinyl radicals species [ 1] + , [ 2] + , and [ 3] + , 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 [ 1] + and [ 2] + . No quinoid bond pattern was present. In contrast, larger structural rearrangements were evidenced for the unsymmetrical [ 3] + , with shortening of one C ortho C meta bond. Radical species [ 1] + and [ 2] + exhibit a strong absorption band at around 6000 cm −1 (class III mixed valence compounds). This band is significantly less intense than [ 3] + , 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.