A C2-Linked Bis-silene Formed without Using Metals and the Transformation into the Bis-silyl and Bis-silylium C4-Cumulenes

Reaction of silylene L(Cl)Si: (1; L = PhC(NtBu)(2)) with 1,3-diyne Me3SiC equivalent to CC equivalent to CSiMe3 produced bis-silene L(Cl)Si-C(SiMe3)C equivalent to C(SiMe3)C-Si(Cl)L (2). This shows a route by oxidative coupling reaction to silenes. Reaction of 2 with AgOSO2CF3 resulted in [L(Cl)(F3CO2SO)Si](Me3Si)C=C=C=C(SiMe3)[Si(OSO2CF3)(Cl)L] (3) and a silver mirror. From the reaction of 2 and B(C6F5)(3) were isolated compounds {[L(Cl)Si](Me3Si)C=C=C=C(SiMe3)[Si(Cl)L]}(2+)center dot 2[ClB(C6F5)(3)](-) (4) and {LSi[mu(2)-C-2(SiMe3)(C equivalent to CSiMe3)]}(2) (5). When 2 was treated with [Ph3C](+)[B(C6F5)(4)](-), compounds [L-2(Cl)Si](+)[B(C6F5)(4)](-) (6) and Ph2C=-cyclo-C(CH-CH)(2)CHCPh3 (7) were formed. These reactions exhibit reduction of the polar Si-C bond to create unusual species of neutral and dicationic C-4-cumulenes. The formation, bonding, and reactivity of compound 2 is explored by the computational quantum mechanical calculations.