Ethene Complexes of Bulky Titanocenes, Their Thermolysis, and Their Reactivity toward 2-Butyne

摘要: Ethene complexes of titanocenes [Ti(II)(η2-C2H4)(Cp′)2] for Cp′ = η5-C5Me5 (1), η5-C5Me4t-Bu (2), η5-C5Me4SiMe3 (3), and η5-C5HMe4 (4) were prepared by reduction corresponding titanocene dichlorides with magnesium in THF the presence ethene. Thermolysis 1–3 toluene solution at a maximum 100 °C resulted elimination ethane, affording cleanly doubly tucked-in compounds 5–7, respectively. Experiments 2 3 NMR tubes proved that symmetrical isomers 6a 7a formed first, these thermally isomerized to thermodynamically more stable asymmetrical 6b 7b. The energy difference between 7b calculated DFT methods was 15.3 kJ/mol. 4 m-xylene required temperature 135 °C, mixture 8b > 8a “dimeric dehydro-titanocene” 9 as concurrent product hydrogen abstraction. In contrast thermolysis solvents, heating 1 high vacuum sublimation known [Ti(C5Me5)2]...