A construction kit for Si-B-C-N ceramic materials based on borazine precursors

Starting from B,B',B"-triethynylborazine (1), an easy construction kit for highly durable Si-B-C-N ceramic materials is presented. Hydrosilylation of 1 with HSiRCl2 (R = Cl, Me, Ph) using Pt/C as catalyst results in the novel precursor molecules 2 and 3. Subsequent linking reactions with MeNH2 or hydrogenation with LiAlH4 leads to the preceramic precursors 4-6. All compounds and polymers have been characterized by NMR and IR spectroscopy and mass spectrometry. The thermal conversion of 4-6 results in various Si-B-C-N ceramics, C8-C10, with tunable Si, C, and N content. Insights into the mechanism of the pyrolysis have been obtained by thermal analysis as well as IR spectroscopy. The chemical composition of the materials is controlled by the reaction pathway as well as by the backbone of the respective precursor molecules.