Bildung siliciumorganischer Verbindungen. 83. Bildung,Reaktionen und Struktur von Yliden aus perchlorierten Carbosilanen |
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| Authors: | G Fritz U Braun W Schick W Hnle H G V Schnering |
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| Institution: | G. Fritz,U. Braun,W. Schick,W. Hönle,H. G. V. Schnering |
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| Abstract: | Formation of Organosilicon Compounds. 83. Formation, Reactions, and Structure of Ylides Generated from Perchlorinated Carbosilanes The CCl-moiety in perchlorinated carbosilanes as (Cl3Si)2 a, Cl3Si? CH2? SiCl2? CCl2? SiCl3 b, (Cl3Si? CCl2)2SiCl2 c or (Cl2Si? CCl2)3 d, e.g., cleaves the Si? P bond of me3Si? Pme2 e (me = CH3); and by subsequent rearrangement ylides are formed. Such, treating e with a yields (Cl3Si)2CPme2Cl 1, which also results from the reaction of me2P? Pme2 with a. The ylides also can be obtained by means of treating the carbosilanes a, b, c or d with LiPme2. Thus, c with one mole of LiPme2 yields Cl3Si? CCl2? SiCl2? C(Pme2Cl)? SiCl3 or Cl3Si? C(Pme2Cl)? SiCl2? C(Pme2Cl)? SiCl3, resp., with two moles of LiPme2. The corresponding Si-methylated derivates do not form ylides; (me3Si)2CCl2, e.g., with e in benzene yields me3Si? CH(Pme2)? Sime3. One mole of Lime methylates 1 to yield (Cl3Si)2CPme3 11. With either LiPme2, me3Si? Pme2 or Me2P? Pme2 1 forms (Cl3Si)2CPme2-Pme2. Reacting 1 with CH3OH/(C2H5)2NH, (Cl3Si)SiCl2(OCH3)]CPme2(OCH3) is formed. Ylides also result from the reactions of partially C-chlorinated 1,1,3,3,5,5-hexachloro-1,3,5-trisilacyclohexanes with me3Si? Pme2, (Cl2Si? CCl2)3 with three moles of me3Si? Pme2 or LiPme2, resp., yields (Cl2Si? CPme2Cl)3 16, the 1,1,3,3,5,5-Hexachlor-2,4,6-tris(chlordimethylphosphoranyliden)-1,3,5-trisilacyclohexan, which crystallizes with one mole of monoglyme. X-ray structure determinations revealed that 1, 11 and 16 are planar. As well the (P? C) as the (Si? C) bond lengths are remarkably shortened; in 1 (P? C) to 173.3 pm, (Si? C) to 173.3 pm, (Si? C) to 179.5 pm, in 16 (P? C) to 168.7 pm, (Si? C) to 180 pm. The (Si? C) and (P? C) bond orders amount to about 1.33, and are relatively equally distributed. Therefore, the charge of the formal carbanion is equally distributed, which shall be expressed by means of the following kind of writing for 1 and 16 see “Inhaltsübersicht”. |
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