STEPWISE SYNTHESIS OF SiOSiN-RINGS AND CAGES

Abstract

Aminosilanols can be stabilized kinetically, e.g. (Me ₃ C) ₂ Si(OH)NH ₂ , which crystallizes in ladder like chains via H-bridges. Its lithium salt was characterized as tetramer, forming a Li─O cubane, while the sodium and potassium salts are hexagonal prisms. The aminosilanol reacts with halosilanes to give amino-1,3-siloxanes. Lithium salts of amino-1,3-disiloxanes were isolated as amido-1,3-siloxanes or silylamino-silanolates. This includes a 1,3-silylgroup migration from the oxygen to nitrogen atom. Lithium salts of fluorofunctional amino-1,3-disiloxanes were characterized by X-ray. They crystallize as monomers or dimers and have unusual types of structures. LiF-elimination from such lithium salts leads to the formation of four- or eight-membered (SiNSiO)-ring systems. The chemical behavior of aminosilanols, the formation of structural isomers and of different ring systems are proved by experiments, crystal structures, and quantum chemical calculations.

Keywords:

• Aminosiloxanes
• lithium salts
• (SiOSiN)-rings

We are grateful to the Fonds der Chemischen Industrie for the financial support of this work.