Functionalized borazines as precursors for new silica gels

Borazine Based Molecular Single Source Precursors for Si/B/N/C Ceramics

“…1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 The constitution of the obtained borazines as determined spectroscopically has been confirmed by single crystal structure analysis (Table 1, Figure 3). As a striking feature, though not unique, the B 3 N 3 -core of the molecule is not planar but in a chair conformation ( Figure 3 [31] and {(SiCl 3 )C 2 H 3 ]BNH} 3 [32]) are planar. (Table 2), the coincidences of the B-Cl and B-CH 3 groups of the individual molecules necessitate the splitting of the 4c site for Cll/C1 and of the 8d site for Cl2/C2 leading to site occupation factors 0.180(3) for Cl1, 0.319(3) for C1, 0.370(4) for Cl2 and 0.629(4) for C2.…”

Synthesis, Structures and Reactivity of Mono‐ and Diborylacetylenes

“…The synthesis of the [bis(diisopropylamino)boryl]acetylenes 5a,b was performed according to a literature procedure [6] by treating chlorobis(diisopropylamino)borane with LiCϵCϪEMe 3 (E ϭ C, Si). The products were isolated in almost quantitative yields (Scheme 3).…”

Influence of methyl‐modified silyl groups on the properties of polymers and Si/B/N/C ceramics derived from N‐silylated borazine derivatives

“…Thus in the case of m = 1, 2 the borazine rings deviate from the expected chair‐shaped form ( m = 0 and 3), showing a twisted boat conformation. Such dependence is a special feature of this kind of N ‐silylated borazine derivative and is not observed for boron‐substituted borazine compounds …”

“…Smaller regions of such Si/N phases are stabilized by turbostratic BN(C) phases due to their ability to bind free carbon and to act as a diffusion barrier . Embedded carbon enhances significantly the thermal stability of such non‐oxide ceramics and can be introduced into the polymer as methyl groups of silyl entities and of —(NMe)— linkages as well as in the form of bridging units like —(CHR)—, —(CHR—CHR)—, —(CH 2 —CH 2 —CH 2 )—, —(HC═CH)— or —(N═C═N)— …”