Facile and Rational Route for High-Yield Synthesis of Titanasiloxanes from Aminosilanetriols

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. 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.