A novel cyclic titanasiloxane derived from [Ph₂Si(OH)]₂O: synthesis and crystal structure of [Cp^_∗Ti(Cl)(OSiPh₂OSiPh₂OSiPh₂O)]

Abstract

Reaction of Cp^∗Ti(OAr)C1₂ (Ar=2,6-Me₂C₆H₃) with dilithium salt of [Ph₂Si(OH)]₂O in a 1:1 molar ratio in toluene at room temperature yields titanatrisiloxane ring compound [Cp^∗Ti(Cl)(OSiPh₂OSiPh₂OSiPh₂O)] (1). Siloxane chain-expansion effect has been observed in the product formation, which is presumed to be a consequence of the ring strain in the titanadisiloxane system. Compound 1 has been characterized by microanalysis, IR, and NMR spectroscopic techniques. The molecular structure of 1 determined by X-ray diffraction reveals that the central eight-membered TiSi₃O₄ siloxane-ring exists in an unusual butterfly-like conformation.