Dihydrogen and Silane Addition to Base-Free, Monomeric Bis(cyclopentadienyl)titanium Oxides

Synthesis of a family of monomeric, base-free bis(cyclopentadienyl)titanium oxide complexes, (η5-C5Me4R)2TiO (R = iPr, SiMe3,
SiMe2Ph), has been accomplished by deoxygenation of styrene
oxide by the corresponding sandwich compound. One example,
(η5-C5Me4SiMe2Ph)2TiO, was characterized by X-ray diffraction.
All three complexes undergo clean and facile hydrogenation at 23
°C, yielding the titanocene hydroxy hydride complexes (η5-C5Me4R)2Ti(OH)H. For (η5-C5Me4SiMe3)2TiO, the kinetics of
hydrogenation were first-order in dihydrogen and exhibited a
normal, primary kinetic isotope effect of 2.7(3) at 23 °C consistent
with a 1,2-addition pathway. Isotope effects of the same direction
but smaller magnitudes were determined for silane addition.