Ceramic Fibers from Organosilicon Polymers

Kalchauer, Wilfried; Geisberger, Gilbert

doi:10.1002/9783527619931.ch60

Cited by 1 publication

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“…Preparation of 2,2,3,3,7,7,8,8-Octamethyl-2,3,5,7,8-pentasilaspiro[4,6]nonane Starting from Tetrakis(lithiomethyl)silane. Cyclic carbosilanes are of interest as starting materials for the preparation of carbosilane polymers and/or Si−C ceramics on pyrolysis of such polymers. Polymeric linear carbosilanes can be produced by ring-opening reactions of 1,3-disilacyclobutanes 16 or thermal rearrangement of polysilanes …”

Section: Resultsmentioning

confidence: 99%

Tris- and Tetrakis(lithiomethyl)silanes: An Easy Access to New Building Blocks for Organosilicon Compounds

2000

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Tris(lithiomethyl)silanes, RSi(CH2Li)3, and tetrakis(lithiomethyl)silane, Si(CH2Li)4, were prepared by the reductive C−S bond cleavage with lithium p,p‘-di-tert-butylbiphenylide (LiDBB) and characterized by trapping with Bu3SnCl. The yields of the isolated trapping products were 42−81% (>95% NMR yield of the crude product), indicating a high-yield synthesis of the corresponding poly(lithiomethyl)silane building blocks. Tetrakis(lithiomethyl)silane is the first compound containing four lithioalkyl groups without any stabilization of the metalated carbon atoms by π-systems. Tetrakis(lithiomethyl)silane was used for the synthesis of 2,2,3,3,7,7,8,8-octamethyl-2,3,5,7,8-pentasilaspiro[4,6]nonane (10), a new spirocyclic disilane. The single-crystal X-ray diffraction study of 10 indicates two five-membered rings in envelope conformation with ecliptically arranged methyl groups connected to a spiro compound by a central silicon atom. DFT geometry optimizations [B3LYP/6-31G(d) level] and NMR calculations (GIAO method, HF/6-31+G(d,p) level) of 10 confirm the observed conformation of 10 as an energetic minimum and support the experimental results.

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Section: Resultsmentioning

confidence: 99%