Facile and rational route for high-yield synthesis of titanasiloxanes from aminosilanetriols

Abstract

Reactions of aminosilanetriols RN(SiMe₃)(Si(OH)₃) (R = 2,6-Me₂C₆H₃ (1a), 2,6-i-Pr₂C₆H₃ (1b), 2,4,6-Me₃C₆H₂ (1c)) with titanium orthoesters Ti(OR')4 (R' = Et, i-Pr) in hexane at room temperature afford new cubic titanasiloxanes [RN(SiMe₃)SiO₃Ti(OR')]₄ (2a-f) in nearly quantitative yield. These compounds have been characterized by mass, IR, and multinuclear NMR spectroscopy. The X-ray crystal structure of [(2,6-i-Pr₂C₆H₃)N(SiMe₃)SiO₃Ti(OEt)]₄ (2c) is described. The molecular structure of 2c reveals a Si₄Ti₄O₁₂ cubic core. The six Si-O-Ti puckered eight-membered rings in the cubic framework adopt a crown conformation with the two Si and two Ti atoms describing a plane and the four oxygen atoms in an almost parallel plane.