Compounds of silicon. 140 - Sterical overloaded compounds of silicon. 24 -Disupersilylsilanes R-2(*)SiX2, disupersilyldisilanes R-2(*)XSi-SiX3, and tetrasupersilyltetrasilanes R-2(*)XSi-SiX2-SiX2-SiXR2(*)

Supersilylsilanes R-2*SiX2, disupersilyldisilanes R-2*XSi-SiX3 and tetrasup ersilyltetrasilanes R-2*:XSi-SiX2-SiX2-SiXR2* (R* = supersilyl = SitBu(3); X = H, Me, Ph, Hal, OH, OTf) are prepared in organic solvents (i) by reacti ons of supersilylhalosilanes R*X(2)SiHal with supersilyl sodium NaR* (Hal/R * exchange), (ii) by reactions of halosilanes X(3)SiHal with silanides NaSi XR2* (Hal/SiXR2* exchange), (iii) by dehalogenations of disupersilylhalodis ilanes R-2*XSi-SiX2-Hal with Na. (iv) by insertions of supersilylsilylenes R*XSi into the NaSi-bond of supersilylsodium NaR*, (v) by reactions of disu persilylated halosilanes and -disilanes R-2*XSiHal and R-2*XSi-SiX(2)Hal wi th H- (Hal/H exchange), (vi) by reactions of the title silanes (X = H) with halogens Hal(2) (H/Hal exchange), (vii) by reactions of the title silanes (X = Hal) first with Na (Hal/Na exchange), then with agents for protonation (Na/H exchange) or halogenation (Na/Hal exchange), (viii) by reactions of the title silanes (X = Hall with nucleophiles like F, H2O (Hal/F or Hal/OH exchange) or (ix) by reactions of the title silanes (X = H) with strong aci ds like HOTf (H/OTf exchange). The colorless compounds are characterized by IR, NMR and X-ray structure analyses (structures of R-2*SiX2 with X = H, F , Cl and R-2*HSi-SiHX-SiHX-SiHR2* with X = H, Br). They may thermolize unde r formation of silylenes (e. g. R-2*SiX2 --> R*X + R*SiX) and are normally stable for hydrolysis. For other reactions confer preparation of the title silanes (i-ix).