Oxidation of Titanocene(III): The Deceptive Simplicity of a Color Change

Evaluation of air-free glassware using the ketyl test

Air-free glassware and techniques are used in most organometallic research laboratories, but their relative effectiveness has not been well studied. We report a method for quantitatively comparing air and moisture exclusion by air-free glassware. Samples of benzophenone dianion in various glassware are monitored by video as their purple color is quenched. Numerical values for time until colorless are extracted from the video data and interpreted as a relative measure of air and moisture exclusion. Low pressure/vacuum (LPV) NMR tubes demonstrated by far the best performance, compared to a variety of Schlenk flasks and standard NMR tubes. The findings are of immediate practical use for synthetic chemists, and the evaluation methods can be used by individual laboratories to assess other conditions for air and moisture exclusion.

The Proven Versatility of Cp2TiCl

In the last two decades, titanocene monochloride has been postulated as a monoelectronic transfer reagent capable of catalyzing an important variety of chemical transformations. In this Perspective, our contributions to this growing field of research are summarized and analyzed. Especially known have been our contributions in C-C bond formation reactions, hydrogen-atom transfer from water to radicals, and isomerization reactions, as well as the development of a catalytic cycle that has subsequently allowed the preparation of a great variety of natural terpenes. It is also worth mentioning our contribution in the postulation of this single-electron transfer agent (SET) as a new green catalyst with a broad range of applications in organic and organometallic chemistry. The most significant catalytic processes developed by other research groups are also briefly described, with special emphasis on the reaction mechanisms involved. Finally, a reflection is made on the future trends in the research of this SET, aimed at consolidating this chemical as a new green reagent that will be widely used in fine chemistry, green chemistry, and industrial chemical processes.

Reactive metallocene cations as sensitive indicators of gas-phase oxygen and water

Gas-phase oxidation of air-sensitive organometallic compounds does not proceed to a significant extent in mass spectrometric analysis unless a vacant coordination site is generated, making nitrogen generators a suitable source of desolvation gas.