M. Sankaralingam, M. Palaniandavar
Jan 8, 2014
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0
Influential Citations
21
Citations
Journal
Polyhedron
Abstract
Abstract A series of non-heme (μ-oxo)bis(μ-benzoato)-bridged diiron(III) complexes of the type [Fe 2 (O)(OBz) 2 (L) 2 ] 2+ ( 1 – 6 ), where OBz = benzoate, L = bis(pyridin-2-ylmethyl)amine (L1), N -((6-methylpyridin-2-yl-)methyl)(pyridin-2-yl)methanamine (L2), N,N -dimethyl- N ′-(pyrid-2-ylmethyl)ethylenediamine (L3), (1-methyl-1 H -imidazol-2-yl)- N- (pyridin-2-ylmethyl)-methanamine (L4), (1 H -benzo[o]imidazol-2-yl)- N- (pyridin-2-ylmethyl)methanamine (L5) and bis((1 H -benzo[o]imidazol-2-yl)methyl)amine (L6), have been isolated and characterized by means of elemental analysis, spectral and electrochemical methods. They have been studied as catalysts for selective hydroxylation of alkanes using m -choloroperbenzoic acid ( m -CPBA) as the oxidant. In acetonitrile/dichloromethane mixed solvent all the complexes display a d–d band characteristic of a triply bridged diiron(III) core, revealing that they retain their identity in solution. Upon replacing a donor atom on the capping ligand by a stronger donor, the E 1/2 value of the one-electron Fe III Fe III → Fe III Fe II reduction becomes more negative. All the complexes function as efficient catalysts for hydroxylation of cyclohexane, with 390–410 total turnover numbers and good alcohol selectivity (A/K, 9.3–12.8). Adamantane is selectively oxidized (3°/2°, 15.7–28.1) to 1-adamantanol and 2-adamantanol, along with a small amount of 2-adamantanone (Total TON, 336–437), and interestingly the 3N capping ligands with the pyridyl donor around the diiron(III) center lead to high 3°/2° bond selectivity.