Bildung siliciumorganischer Verbindungen. 97. Über den Einfluß der Si-Substituenten (Me,Cl) auf Bildung und Reaktion von Yliden

Formation of Organosilicon Compounds. 97. About the Influence of the Si-Substituents (Me, Cl) upon the Formation and the Reactions of Ylides 1,3-disilapropanes with different grade of chlorination or methylation at the silicon atoms and containing a CCl₂ group cleave the Si? P bond of Me₃SiPMe₂. By subsequent rearrangement ylides with ? PMe₂Cl group are formed. The reactivity of the CCl₂ group depends on the grade of Si-chlorination resp. Si-methylation. Si-methylation decreases the reactivity of the CCl₂ group. The reaction of 1,3-disilapropanes and Me₃SiPMe₂ (molar ratio 1:1) runs in a sequence shown in “Inhaltsübersicht”. Ylid C is able either to react with the initial compound A forming B, or in competition decomposes forming D. Reacting Si-perchlorinated carbosilanes, the decomposition forming D is not to be observed. In Si-methylated ylides like (Me₃Si)₂C?PMe₂? PMe₂ and (Me₃Si)₂C?PMe₂? P(Me)SiMe₃ the ylid carbon atom is able to abstract a proton of the P? CH₃ group resp. P? H groups of the trivalent phosphorus forming (Me₃Si)₂C(H)PMe₂. The rearrangement is proved by deuterated derivatives. The different behaviour is due to the increased basicity of the ylid-C atom in Si-methylated phosphorus ylides. Quite the same behaviour show the phosphorus ylides of 1,3,5-trisilacyclohexane.