Free radical polymerization of ethylene in an intermediate pressure and temperature range (P(ethylene) < 250 bar and 50 °C < T < 90 °C) in the presence of an organic solvent has been studied. Under selected conditions (P, T) and according to the amount of organic solvent added, either a supercritical monophasic or a biphasic medium is obtained. In the case of a biphasic medium, polymerization o...

The iron(IV) nitrido complex PhB(MesIm)3Fe≡N reacts with 1,3-cyclohexadiene to yield the iron(II) pyrrolide complex PhB(MesIm)3Fe(η(5)-C4H4N) in high yield. The mechanism of product formation is proposed to involve sequential [4 + 1] cycloaddition and retro Diels-Alder reactions. Surprisingly, reaction with 1,4-cyclohexadiene yields the same iron-containing product, albeit in substantially lowe...

The reaction of hydrogen sulfide with ground-state atomic carbon was examined with crossed molecular beams experiments and ab initio calculations. The thiohydroxycarbene molecule, HCSH, was the reactive intermediate, which fragmented into atomic hydrogen and the thioformyl radical HCS. This finding may account for the unassigned HCS source and an unidentified HCSH radical needed to match observ...

Various continuous-wave and pulse electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) experiments performed on the radical species occurring in photosynthetic reaction centers of plants and bacteria during light-induced charge separation are reviewed here. Emphasis is placed on time-resolved experiments performed on short-lived intermediate states such as radical...

The reaction of H2O2 with thioanisole and p-methoxythioanisole catalysed by lignin peroxidase from Phanerochaete chrysosporium has been studied spectrophotometrically under turnover and single turnover conditions with a stopped-flow apparatus. Pre-formed lignin peroxidase compounds I and II are each able to react with the sulphides to form a sulphide radical cation. The radical cation is then c...

Title of Dissertation: AQUEOUS PHOTOCHEMISTRY OF 1,4BENZOQUINONES AND THEIR POSSIBLE ROLE IN THE PHOTOCHEMISTRY OF NATURAL ORGANIC MATTER Daqing Gan, Doctor of Philosophy, 2005 Dissertation Directed By: Professor Neil V. Blough Department of Chemistry and Biochemistry Past research implicated the presence of an organic species as a photochemical source of OH radical in natural waters. Quinones ...

Building upon our recent studies of radical addition pathways following excitation of the I2 chromophore in the donor-acceptor complex of ethylene and I2 (C2H4···I2), in this article, we extend our studies to examine photoinduced electron transfer. Thus, irradiation into the intense charge-transfer band of the complex (λmax = 247 nm) gave rise to a band at 366 nm that is assigned to the bridged...

The enzyme, ribonucleotide reductase, catalyses the formation of deoxyribonucleotides from ribonucleotides, a reaction essential for DNA synthesis in all living cells. The Escherichia coli ribonucleotide reductase, which is the prototype of all known eukaryotic and virus-coded enzymes, consists of two nonidentical subunits, proteins B1 and B2. The B2 subunit contains an antiferromagnetically co...