Oxidation of Alcohols and Activated Alkanes with Lewis Acid-Activated TEMPO

The reactivity of MCl3(η(1)-TEMPO) (M = Fe, 1; Al, 2; TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl) with a variety of alcohols, including 3,4-dimethoxybenzyl alcohol, 1-phenyl-2-phenoxyethanol, and 1,2-diphenyl-2-methoxyethanol, was investigated using NMR spectroscopy and mass spectrometry. Complex 1 was effective in cleanly converting these substrates to the corresponding aldehyde or ketone. Complex 2 was also able to oxidize these substrates; however, in a few instances the products of overoxidation were also observed. Oxidation of activated alkanes, such as xanthene, by 1 or 2 suggests that the reactions proceed via an initial 1-electron concerted proton-electron transfer (CPET) event. Finally, reaction of TEMPO with FeBr3 in Et2O results in the formation of a mixture of FeBr3(η(1)-TEMPOH) (23) and [FeBr2(η(1)-TEMPOH)]2(μ-O) (24), via oxidation of the solvent, Et2O

Selectivity and Mechanism of Hydrogen Atom Transfer by an Isolable Imidoiron(III) Complex

This article discusses a mechanistic study of hydrogen atom transfer by an isolable iron (III) imido complex, LᴹᵉFeNAd (Lᴹᵉ = bulky β-diketiminate ligand, 2,4-bis(2,6-diisopropylphenylimido)pentyl; Ad = 1-adamantyl)

Steric and Electronic Control of the Spin State in Three-Fold Symmetric, Four-Coordinate Iron(II) Complexes

The three-fold symmetric, four-coordinate iron(II) phosphoraminimato complexes PhB(MesIm)3Fe− N=PRR′R″ (PRR′R″ = PMePh2, PMe2 Ph, PMe3, and PnPr3) undergo a thermally induced S = 0 to S = 2 spincrossover in fluid solution. Smaller phosphoraminimato ligands stabilize the low-spin state, and an excellent correlation is observed between the characteristic temperature of the spincrossover (T1/2) and the Tolman cone angle (θ)....

Tuning the Reactivity of TEMPO by Coordination to a Lewis Acid: Isolation and Reactivity of MCl₃(η¹‑TEMPO) (M = Fe, Al)

Addition of 2,2,6,6-tetramethylpiperidine-<i>N</i>-oxyl (TEMPO) to MCl₃ (M = Fe, Al) results in the formation of MCl₃(η¹-TEMPO) [M = Fe (<b>1</b>), Al (<b>2</b>)]. Both <b>1</b> and <b>2</b> oxidize alcohols to generate ketones or aldehydes along with the reduced complexes MCl₃(η¹-TEMPOH) [M = Fe (<b>3</b>), Al (<b>4</b>)]. Complexes <b>1</b>–<b>4</b> were fully characterized, including analysis by X-ray crystallography. Additionally, control experiments indicated that neither MCl₃ (M = Al, Fe) nor TEMPO are capable of effecting the oxidation of alcohols independently