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)₂TiO (R = ⁱPr, SiMe₃, SiMe₂Ph), has been accomplished by deoxygenation of styrene oxide by the corresponding sandwich compound. One example, (η⁵-C₅Me₄SiMe₂Ph)₂TiO, 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)₂TiO, 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.