Preparation of iron amido complexes via putative Fe(IV) imido intermediates.
The isolation and characterization of monomeric Fe(III) amido complexes with hybrid ureate/amidate ligands is described. An aryl azide serves as the source of the amido ligand in preparing the complexes from trigonal monopyramidal Fe(II) precursors. Aryl azides more commonly react with transition metal complexes by a two-electron oxidation process to yield imido complexes, suggesting that the Fe(III) amido complexes may be formed from high valent species by hydrogen atom abstraction from an external species. The mechanistic basis for formation of the amido complexes is investigated using substrates that readily donate hydrogen atoms. Results from these experiments suggest that the Fe(III) amido complexes are generated from Fe(IV) imido intermediates that can facilitate homolytic X-H bond cleavage. The Fe(III) amido complexes are high spin (S = 5/2) with a strong absorbance band at lambdamax approximately 600 nm and extinction coefficients between 2000 and 3000 M-1 cm-1. These complexes are hygroscopic, reacting with 1 equiv of water to produce the corresponding Fe(III)-OH complexes and p-toluidine.
Lucas
Robie L
RL
Department of Chemistry, University of Kansas, 2010 Malott Hall, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, USA.
Powell
Douglas R
DR
Borovik
A S
AS
D000577:Amides / Q000138:chemical synthesis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D007094:Imides / Q000138:chemical synthesis / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis*; D013237:Stereoisomerism
D000577:Amides; D007094:Imides; D009942:Organometallic Compounds; D007501:Iron