CO 2 as an Oxygen Source for Polysiloxanes – Preparation, Crystal Structure and Thermal Decomposition of Two Novel Silylcarbamates

Diaminosilanes (CH 3 ) 2 Si(NHR) 2 1a, b are obtained from dichlorodimethylsilane and primary amines (R = n-hexyl, iso-propyl) in good yields. Bis-insertion of CO 2 into the Si-N bonds of the aminosilanes quantitatively gives the silylcarbamates (CH 3 ) 2 Si(OCONHR) 2 , 2a, b. Oligo- and polydimethylsiloxanes 3a, b as well as N,N`-substituted ureas CO(NHR) 2 4a, b are formed upon heating the silylcarbamates 2a, b to ~ 150 ◦C. The results of comprehensive NMR analyses of the aminosilanes, the two novel bis-silylcarbamates, the siloxanes and the ureas, and of single-crystal structure analyses of 2a and 4b are presented. In the crystal the n-hexyl silylcarbamate 2a shows a similar molecular packing arrangement as the iso-propyl urea derivative 4b. CO 2 as an Oxygen Source for Polysiloxanes – Preparation, Crystal Structure and Thermal Decomposition of Two Novel Silylcarbamates