Supersilylsilane R*SiX3: Umwandlung in Disilane R*X2Si-SiX2R*, Silylene R*XSi, Cyclosilane (R*XSi)n, Disilene R*XSi=SiXR*, Tetrasupersilyl-tetrahedro-tetrasilan [1] / Supersilylsilanes R*SiX3: Conversion into Disilanes R*X2Si-SiX2R*, Silylenes R*XSi, Cyclosilanes (R*XSi)n, D isilenes R*XSi=SiXR*, Tetrasupersilyl-tetrahedro-tetrasilane [1]

Abstract

Supersilylmonohalosilanes R*R SiHCl (R * = Supersilyl = SitBu3) react with Na in C6H6 at 65 °C or with NaC10H8 in THF at - 78 °C with formation of disupersilyldisilanes R*RHSi- SiHRR * in quantitative (R = H , Me) or moderate yields (R = Ph). In the latter case, R *PhSiH2 is obtained additionally at 65 °C (exclusively with Na in THF at 65 °C). Obviously, the supersilylsilanides NaSiHRR* are generated as interm ediates which react with educts R *RSiHCl with NaCl elimination and formation of R*RHSi-SiHRR* (R = H , Me) or R *RSiH2 and R *R Si (R = Ph). The silylene intermediate R*PhSi inserts into the SiH -bonds of the educt R*PhSiHCl and of the product R *PhSiH2 with formation of the disupersilyldisilanes R*PhSiH -SiClPhR* and R*PhSiH -SiHPhR* which are reduced by Na at 65 °C to R*PhSiH2 (and by NaC10H8 at low tem peratures to give R*PhSiH-SiHPhR*). The addition of NaR * to R*RSiHCl in THF at low temperatures leads with NaCl elimination to R*2RSiH (R = H , Me) or to R*RHSi-SiHRR* (R = Me) besides R*C1, or to R*RHSi-SiClRR* (R = Ph) besides R*H and NaR , whereas the addition of R*PhSiH Cl to NaR* in THF at low temperatures results in the formation of NaSiPhR*2 besides R*H and NaCl. In the latter cases (R = Ph), NaR* react with R*PhSiHCl to release the silylene R*PhSi, the transistory existence of which could be proven by trapping it with Et3SiH (formation of R *Ph(Et3Si)-SiH ). Subsequently, R*PhSi inserts into the SiH bond of R*PhSiH Cl (addition of NaR* to R*PhSiHCl) or into the NaSi bond of NaR * (addition of R*PhSiHCl to NaR *). - Supersilyldihalosilanes R*SiHCl2 are converted by Mg in C6H6 at 65 °C into cyclosilanes (R *SiH)n (n = 3, 4) and R*PhSiBrCl by Na at low temperatures - via the silylene R*PhSi - into the disilene R*PhSi=SiPhR*. which is reduced by excess Na to an anion radical. - Supersilyltrihalosilanes R*SiBr2Cl, R*SiBr3 and R*SiI3 react with Na, NaC10H8 or NaR* in T H F with formation of tetrasupersilyl-terrahedro-tetrasilane (R*Si)4 in quantitative yields, whereas the reactions of R*SiCl3 with LiC10H8 in THF at 45 °C lead to (R*Si)4 only in m oderate yields. Obviously, the tetrahedrane is formed from R*SiHal3 via R*SiHal2Na and R*HalSi=SiHalR* as reaction intermediates. The results lead to the following conclusions: (i) Silylenes play a rôle in dehalogenation of “sterically overloaded" supersilylhalosilanes R*R3-nSiHaln· - (ii) A straight-forward procedure for a high-yield synthesis of (R *Si)4 from easily available educts consists in supersilanidation of SiH2Cl2 with NaR*, bromination of the formed supersilylsilane R*SiH2Cl with Br2 and dehalogenation of the bromination product R*SiBr2Cl with Na.