Titanium complexes hydrogen shift

As shown in Scheme 23, a low-valence chiral an.sa-bis(indenyl)titanium complex catalyzes 1,3-hydrogen shift of trans-4-tert-buxy -1 -vinylcy-clohexene, an unfunctionalized meso olefin, to give an axially asym-... 

Interestingly, a similar process is observed for the thermal decomposition of dimethylbis(pentamethylcyclopentadienyl)titanium(IV) (65). The decomposition takes place at elevated temperatures around about 110 °C and results in the formation of fulvene complex 68 and methane. Extensive labeling experiments and kinetic measurements resulted in two reaction pathways compatible with the experimental observations. Either one involves a titanium methylene species 66 as the key intermediate. The next step is an intramolecular C,H-activation leading to fulvene complex 67, similar to the formation of 63. Einally, a hydrogen shift accounts for the final product, fulvene complex 68 (Scheme 10.23) [71]. 

In this report we present results of a study of a titanium - ethylene complex formed in an ultra high vacuum chamber and collected on a quartz sensor for mass analysis. The technique we use for mass analysis is unique. It is based on the application of a frequency modulation method to unambiguously track the resonant frequency of a quartz sensor to better than 0.1 ppm. A downward shift in the resonant frequency of the sensor, either due to the initial deposition of the complex or due to the absorption of hydrogen gas, indicates a mass accumulation on its face. This shift can be measured with a 0.1 ppm resolution. 

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