Synthesis and crystal structures of μ-1,3-bis(η5-tetramethylcyclopentadienyl)-1,1,3,3-tetramethyldisiloxane)[η2-bis(trimethylsilyl)ethyne]titanium(II) and a doubly tucked-in product of its thermolysis

Reduction of dichloro-{1,3-bis(η5-tetramethylcyclopentadienyl)-1,1,3,3-tetramethyldisiloxane}titanium(IV), [TiCl2{η5:η5-(C5Me4SiMe2)2O}] (1), with magnesium in the presence of bis(trimethylsilyl)ethyne affords the ansa-[Ti{η5:η5-(C5Me4SiMe2)2O}(η2-Me3SiCCSiMe3)] (2) complex in high yield. Compound 2 is thermally robust, decomposing at 170 °C in high vacuum with liberation of 1,2-bis(trimethylsilyl)ethene to give predominantly an asymmetric, allydiene complex ansa-[Ti{(η5-C5Me4)SiMe2OSiMe2{η3:η4-C5Me2(CH2)2}] (3) as a result of twofold CH bond activation. Crystal structures of 2 and 3 were determined by X-ray diffraction.