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N-propylsulfanyl and isopropylsulfanyl substituted 2,5-di(1,3-dithiol-2-ylidene)-1,3-dithiolane-4-thione derivatives with methoxycarbonyl groups were synthesized, and their redox and electronic properties and crystal structures were investigated. Solid-state absorption spectra showed that both derivatives absorb almost all visible light. Furthermore isopropylsulfanyl-substituted derivatives absorb near-infrared light and the absorption edge reaches around 1320 nm. The crystal structures show that both derivatives are stacked in one dimension to form a columnar structure, but the molecular arrangements of their columns were quite different from each other. The stacked n-propylsulfanyl derivatives kept their orientation of thiocarbonyl groups in the same direction and the one molecule of the isopropylsulfanyl derivatives were rotated in relation to each other by an angle of 56° about their longer molecular axis. The TD-DFT calculation of stacked molecules suggests that the molecular arrangement among the st...

Two methoxycarbonyl-substituted 2,5-di(1,3-dithiol-2-ylidene)-1,3-dithiolane-4-thione derivatives with alkylsulfanyl groups of different sizes were synthesized, and their redox and electronic prope...

Production of O atoms, H(D) atoms, and OH(OD) radicals was confirmed in the catalytic decomposition of H2O(D2O) on a heated Ir filament by laser spectroscopic techniques, such as vacuum-ultraviolet laser-induced fluorescence. The highest steady-state OH density achieved was 2 10 11 cm -3 . The filament temperature dependences of the radical densities were not Arrhenius-type, in contrast to the results on the decomposition of H2 and O2. Especially, OH(OD) density decreased with the increase in the filament temperature over 2100 K. The decomposition process changes from the production of H+OH(D+OD) to that of 2H+O(2D+O) with the increase in the catalysis temperature. This change in the exit channel could not be reproduced by model calculations using the CHEMKIN software package when Arrhenius-type temperature dependences were assumed for the elementary-step rate constants on surfaces. It is necessary to assume that the desorption energy of OH(OD) is surface coverage dependent.

Efficient production of H atoms, O atoms and OH radicals was confirmed by laser spectroscopic measurements in the catalytic decomposition of H2, O2 and their mixtures on a heated Ir filament. No change in electric resistivity was observed when the filament was kept at 2350 K in the presence of 1.0 Pa of pure O2, showing that oxidation is minor. Arrhenius-type temperature dependences were observed for the densities of H (O) atoms in pure H2 (O2) systems. In the H2/O2 mixed system, the H-atom density was almost independent of the O2 partial pressure, although the O-atom and OH-radical densities increased with the O2 pressure. These O2 pressure dependences are completely different from those observed for W. Ir is less poisoned by O2 compared to W. In addition, direct production of H2O molecules on Ir surfaces must take place besides the production of radical species.

2-Phenylnaphtho[1,8-de][1,3]dithiin 1-oxide (4a), 5-phenyl[1]benzothieno[4,3,2-def][1,3]benzodithiepin 4-oxide (4b), and 2-phenyldibenzo[d,f][1,3]dithiepin 1-oxide (4c) underwent facile consecutive photochemical reactions to give the corresponding disulfide, naphtho[1,8-cd][1,2]dithiole (1a), [1]benzothieno[4,3,2-cde][1,2]benzodithiin (1b), and dibenzo[c,e][1,2]dithiin (1c) and benzaldehyde (7), respectively, via the sulfur-sulfur (S…S) interaction. The proposed mechanism for these photochemical reactions is based on the quantum yields measurements, photo-intensity effects, and sensitizer effects. Ab initio calculations were also carried out for a model compound of the primary photoproduct, which showed that the S…S distance becomes shorter and the S-O distance becomes longer upon the excitation to the S1 state.

4,8,10-Trithiadibenzo[cd,ij]azulene 8-oxides were prepared and their photolysis provided a convenient procedure to yield the corresponding aldehydes and ketones together with 4,8,9-trithiacyclopenta[def]phenanthrene.

Production of O atoms was confirmed in the catalytic decomposition of O2, NO, N2O and NO2 on a heated Ir filament. No change in electric resistivity was observed when the filament was kept at 2350 K in the presence of 0.8 Pa of these species, showing that oxidation is not taking place under such conditions. The O-atom densities were evaluated by a vacuum-ultraviolet (vuv) laser-induced fluorescence technique at 130.2 nm as well as a vuv laser absorption technique, by which the absolute values can be evaluated. Arrhenius-type filament temperature dependences were observed for the O-atom densities in all systems. The activation energies for nitrogen oxides were similar, but that for O2 was smaller. The O-atom density was the highest when O2 was used as a source gas and the density could be increased up to 2 × 1012 cm−3. The O-atom density increased with the oxidant pressures, but showed saturation. The possible causes of such behaviours are discussed on the basis of the changes in the coverage conditions of the catalyst surfaces.

4,8,10-Trithiadibenzo[cd,ij]azulene 8-oxides were prepared and their photolysis provided a convenient procedure to yield the corresponding aldehydes and ketones together with 4,8,9-trithiacyclopenta[def]phenanthrene.