Hydrogenation of titanocene and zirconocene bis(trimethylsilyl)acetylene complexes

摘要: Reactions following the addition of dihydrogen under maximum atmospheric pressure to bis(trimethylsilyl)acetylene (BTMSA) complexes titanocenes, [(η5-C5H5−nMen)2Ti(η2-BTMSA)] (n = 0, 1, 3, and 4) (1A–1D), zirconocenes, [(η5-C5H5−nMen)2Zr(η2-BTMSA)] 2–5) (4A–4D), proceeded in diverse ways and, depending on metal, afforded different products. The former lost, all cases, their BTMSA ligand via its hydrogenation bis-1,2-(trimethylsilyl)ethane when reacted at 80 °C for a prolonged reaction time. For n titanocene species formed situ dimerised formation fulvalene ligands two bridging hydride ligands, giving known green dimeric titanocenes (2A–2C). 4, [(η5-C5HMe4)2TiH] (2D) was formed, similarly [(η5-C5Me5)2TiH] (2E) 5; however, contrast this example, 2D absence spontaneously dehydrogenated Ti(III)–Ti(III) dehydro-dimer [{Ti(η5-C5HMe4)(μ-η1:η5-C5Me4)}2] (3B). This complex has now been fully characterised spectroscopic methods, shown through EPR spectroscopy attain an intramolecular electronic triplet state. zirconocene-BTMSA 4A–4D uniformly with one hydrogen molecule give Zr(IV) zirconocene alkenyls, [(η5-C5H5−nMen)2ZrH{C(SiMe3)CH(SiMe3)}] (5A–5D). These were identified 1H 13C NMR spectra, which show features typical agostically bonded proton, CH(SiMe3). Compounds 5A–5D equilibria temperature.