Low temperature reaction of [Fe(TPA)(CH3CN)2]2+ with excess 3-chloroperoxybenzoic acid in semi-frozen acetonitrile; EPR detection of an acylperoxo iron(III) adduct
摘要:
Treatment of [(TPA)Fe-II(CH3CN)(2)](2+) (TPA = tris(2-pyridylmethyl)amine) with excess (>= 2 Eq) of 3-chloroperoxybenzoic acid (mCPBA) in semi-frozen acetonitrile in liquid N-2 vapour generates a rhombic EPR signal assigned to the S = 1/2 low spin acylperoxoiron(III) species [(TPA)Fe(O3CC6H4-3Cl)(CH3CN)](2+) 5; the elusive precursor on the pathway to [(TPA)Fe-III(5-chlorosalicylate)](+) 4 via putative [(TPA) Fe-v(O)(O2CC6H4-3Cl)](2+). Formation of cyclohexene epoxide in the presence of added cyclohexene at low temperatures (<-40 degrees C) suggests that intermolecular alkene epoxidation competes successfully with the intramolecular reactions involving 5 to generate 4. (C) 2012 Elsevier B.V. All rights reserved.