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.
Supersilylmonohalosilanes R*R SiHCl(R* = Supersilyl = SitBu3)在65°C下与C6H6中的Na反应,或者在-78°C下与THF中的NaC10H8反应,形成双超硅基二硅烷R*RHSi-SiHRR*,其产率为定量(R = H,Me)或中等产率(R = Ph)。在后一种情况下,还在65°C下额外获得R*PhSiH2(仅与在65°C下的THF中的Na反应)。显然,超硅基硅化物NaSiHRR*作为中间体生成,它们与反应物R*RSiHCl反应,消除NaCl并形成R*RHSi-SiHRR*(R = H,Me)或R*RSiH2以及R*R Si(R = Ph)。硅烯中间体R*PhSi插入到反应物R*PhSiHCl和产物R*PhSiH2的SiH键中,形成双超硅基二硅烷R*PhSiH -SiClPhR*和R*PhSiH -SiHPhR*,它们在65°C下被Na还原为R*PhSiH2(在低温下通过NaC10H8还原为R*PhSiH-SiHPhR*)。在低温下,将NaR*添加到THF中的R*RSiHCl中,与NaCl消除形成R*2RSiH(R = H,Me)或R*RHSi-SiHRR*(R = Me),此外还有R*C1,或者R*RHSi-SiClRR*(R = Ph)以及R*H和NaR,而将R*PhSiHCl添加到NaR*中在低温下的THF中,结果形成NaSiPhR*2,此外还有R*H和NaCl。在后一种情况下(R = Ph),NaR*与R*PhSiHCl反应释放出硅烯R*PhSi,其瞬时存在性通过用Et3SiH捕获它来证实(形成R*Ph(Et3Si)-SiH)。随后,R*PhSi插入到R*PhSiHCl的SiH键中(将NaR*添加到R*PhSiHCl)或插入到NaR*的NaSi键中(将R*PhSiHCl添加到NaR*)。超硅基二卤代硅烷R*SiHCl2在65°C下通过Mg转化为环硅烷(R*SiH)n(n = 3, 4),并且在低温下通过Na转化为R*PhSiBrCl - 通过硅烯R*PhSi - 转化为双硅烯R*PhSi=SiPhR*,过量Na还原为阴离子自由基。超硅基三卤代硅烷R*SiBr2Cl、R*SiBr3和R*SiI3与Na、NaC10H8或NaR*在THF中反应,形成四超硅基四面体四硅烷(R*Si)4,产率定量,而R*SiCl3与LiC10H8在45°C下反应,只以中等产率形成(R*Si)4。显然,四面体烷是从R*SiHal3通过R*SiHal2Na和R*HalSi=SiHalR*作为反应中间体形成的。结果得出以下结论:(i)硅烯在“立体过载”的超硅基卤代硅烷R*R3-nSiHaln的脱卤作用中发挥作用;(ii)从易获得的反应物中合成(R*Si)4的高产率方法是将SiH2Cl2与NaR*进行超硅基化,用Br2对形成的超硅基硅烷R*SiH2Cl进行溴化,再用Na对溴化产物R*SiBr2Cl进行脱卤。