Reactions of 10-methyl-9,10-dihydroacridine with inorganic oxidants

Reactions of 10-methyl-9,10-dihydroacridine with various inorganic oxidants in 20% acetonitrile/80% water solvent mixture fall into two categories depending on the strength of the oxidant used. Rapid electron transfer to the strong oxidizing reagents, Ce IV and IrCl62-, produces dihydroacridine radical cations, AcrH2·+ ([lambda] max 650 nm). This is followed by the rate-determining loss of a proton and rapid oxidation of thus formed AcrH· by the second equivalent of Ce IV or IrCl62-. The protonation of AcrH· and deprotonation of AcrH2·+ exhibit significant kinetic isotope effects. The use of d2-acridine in H2O/CH3CN yields the secondary and solvent isotope effects separately. A large normal secondary isotope effect of 1.86 ± 0.17 for the protonation of the acridinium radical suggests a possibility of nuclear tunneling. The reaction of dihydroacridine with a mild oxidizing reagent, Fe3+, is slow and shows no kinetic isotope effect. The initial electron transfer from AcrH2 to Fe3+ is believed to be rate-determining;The oxidation of AcrH2 to AcrH+ by hydrogen chromate ions is a chain reaction that is strongly inhibited by oxygen. The initiation reaction between AcrH2 or AcrD2 and H2CrO4 forms AcrH2·+ and occurs by a 1e mechanism, kH = kD = 4.6x102 L mol-1s-1 (25°C). The Cr V produced along with AcrH· (from the acid ionization of AcrH2·+ are chain-carrying intermediates. The propagating reaction between AcrH2 and Cr V, k = 1 x 108 L mol-1s-1, is of key importance since it is a branching reaction that yields two chain carriers, AcrH· and CrO2+, by hydrogen atom abstraction. The same partners react competitively by hydride ion abstraction, to yield Cr3+ and AcrH+, k = 1.2 x 107 L mol-1 s-1, in the principal termination step. The reaction of CrO2+ and AcrH2, kH = 1.0 x 104 and kD = 4.8 x 103 L mol-1 s-1, proceeds by hydride ion transfer. The Cr2+ so produced could be trapped as CrOO2+ when O2 was present, thereupon terminating the chain. AcrH2 itself reacts with Cr2O72- + H+, k = 5.6 x 103 L2 mol-2s-1, but this step is not an initiating reaction. From that, two successive electron transfer steps are believed to occur, yielding CrIV + CrVI + AcrH+

Synthesis of Monomeric Fe(II) and Ru(II) Complexes of Tetradentate Phosphines

rac-Bis[{(diphenylphosphino)ethyl}-phenylphosphino]methane (DPPEPM) reacts with iron(II) and ruthenium(II) halides to generate complexes with folded DPPEPM coordination. The paramagnetic, five-coordinate Fe(DPPEPM)Cl2 (1) in CD2Cl2 features a tridentate binding mode as established by 31P{1H} NMR spectroscopy. Crystal structure analysis of the analogous bromo complex, Fe(DPPEPM)Br2 (2) revealed a pseudo-octahedral, cis-α geometry at iron with DPPEPM coordinated in a tetradentate fashion. However, in CD2Cl2solution, the coordination of DPPEPM in 2 is similar to that of 1 in that one of the external phosphorus atoms is dissociated resulting in a mixture of three tridentate complexes. The chloro ruthenium complex cis-Ru(κ4-DPPEPM)Cl2 (3) is obtained from rac-DPPEPM and either [RuCl2(COD)]2 [COD = 1,5-cyclooctadiene] or RuCl2(PPh3)4. The structure of 3 in both the solid state and in CD2Cl2 solution features a folded κ4-DPPEPM. This binding mode was also observed in cis-[Fe(κ4-DPPEPM)(CH3CN)2](CF3SO3)2 (4). Addition of an excess of CO to a methanolic solution of 1 results in the replacement of one of the chloride ions by CO to yieldcis-[Fe(κ4-DPPEPM)Cl(CO)](Cl) (5). The same reaction in CH2Cl2 produces a mixture of 5and [Fe(κ3-DPPEPM)Cl2(CO)] (6) in which one of the internal phosphines has been substituted by CO. Complexes 2, 3, 4, and 5 appear to be the first structurally characterized monometallic complexes of κ4-DPPEPM

An aqueous non-heme Fe(iv)oxo complex with a basic group in the second coordination sphere

The Fe(IV)oxo complex of a coordinatively flexible multidentate mono-carboxylato ligand is obtained by the one electron oxidation of a low spin Fe(III) precursor in water

The Reaction of a High‐Valent Nonheme Oxoiron(IV) Intermediate with Hydrogen Peroxide

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91353/1/5472_ftp.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/91353/2/ange_201200901_sm_miscellaneous_information.pd

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

Reactions of 10-methyl-9,10-dihydroacridine with inorganic oxidants

Reactions of 10-methyl-9,10-dihydroacridine with various inorganic oxidants in 20% acetonitrile/80% water solvent mixture fall into two categories depending on the strength of the oxidant used. Rapid electron transfer to the strong oxidizing reagents, Ce IV and IrCl62-, produces dihydroacridine radical cations, AcrH2·+ ([lambda] max 650 nm). This is followed by the rate-determining loss of a proton and rapid oxidation of thus formed AcrH· by the second equivalent of Ce IV or IrCl62-. The protonation of AcrH· and deprotonation of AcrH2·+ exhibit significant kinetic isotope effects. The use of d2-acridine in H2O/CH3CN yields the secondary and solvent isotope effects separately. A large normal secondary isotope effect of 1.86 ± 0.17 for the protonation of the acridinium radical suggests a possibility of nuclear tunneling. The reaction of dihydroacridine with a mild oxidizing reagent, Fe3+, is slow and shows no kinetic isotope effect. The initial electron transfer from AcrH2 to Fe3+ is believed to be rate-determining;The oxidation of AcrH2 to AcrH+ by hydrogen chromate ions is a chain reaction that is strongly inhibited by oxygen. The initiation reaction between AcrH2 or AcrD2 and H2CrO4 forms AcrH2·+ and occurs by a 1e mechanism, kH = kD = 4.6x102 L mol-1s-1 (25°C). The Cr V produced along with AcrH· (from the acid ionization of AcrH2·+ are chain-carrying intermediates. The propagating reaction between AcrH2 and Cr V, k = 1 x 108 L mol-1s-1, is of key importance since it is a branching reaction that yields two chain carriers, AcrH· and CrO2+, by hydrogen atom abstraction. The same partners react competitively by hydride ion abstraction, to yield Cr3+ and AcrH+, k = 1.2 x 107 L mol-1 s-1, in the principal termination step. The reaction of CrO2+ and AcrH2, kH = 1.0 x 104 and kD = 4.8 x 103 L mol-1 s-1, proceeds by hydride ion transfer. The Cr2+ so produced could be trapped as CrOO2+ when O2 was present, thereupon terminating the chain. AcrH2 itself reacts with Cr2O72- + H+, k = 5.6 x 103 L2 mol-2s-1, but this step is not an initiating reaction. From that, two successive electron transfer steps are believed to occur, yielding CrIV + CrVI + AcrH+.</p

Iron catalysis in oxidation by ozone

A means and method for improving ozone oxidation through the addition of aniron(II) catalyst is described.</p

Formation of Aggregate-Free Gold Nanoparticles in the Cyclodextrin-Tetrachloroaurate System Follows Finke–Watzky Kinetics

Cyclodextrin-capped gold nanoparticles are promising drug-delivery vehicles, but the technique of their preparation without trace amounts of aggregates is still lacking, and the size-manipulation possibility is very limited. In the present study, gold nanoparticles were synthesized by means of 0.1% (w/w) tetrachloroauric acid reduction with cyclodextrins at room temperature, at cyclodextrin concentrations of 0.001 M, 0.002 M and 0.004 M, and pH values of 11, 11.5 and 12. The synthesized nanoparticles were characterized by dynamic light scattering in both back-scattering and forward-scattering modes, spectrophotometry, X-ray photoelectron spectroscopy, transmission electron microscopy and Fourier-transform infrared spectroscopy. These techniques revealed 14.9% Au1+ on their surfaces. The Finke–Watzky kinetics of the reaction was demonstrated, but the actual growth mechanism turned out to be multistage. The synthesis kinetics and the resulting particle-size distribution were pH-dependent. The reaction and centrifugation conditions for the recovery of aggregate-free nanoparticles with different size distributions were determined. The absorbances of the best preparations were 7.6 for α-cyclodextrin, 8.9 for β-cyclodextrin and 7.5 for γ-cyclodextrin. Particle-size distribution by intensity was indicative of the complete absence of aggregates. The resulting preparations were ready to use without the need for concentration, filtration, or further purification. The synthesis meets the requirements of green chemistry