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The push−pull effect has been widely used to effectively tune Ï€-electron systems. Herein, we report the synthesis and properties of 1-amino-2-boryldisilene 1 as the first push−pull disilene. Its spectroscopic and structural features show substantial interactions between the Si═Si double bond and the amino and boryl substituents. The Ï€ → Ï€* absorption band of 1 is remarkably red-shifted compared to that of the corresponding alkyl-substituted disilene 2. Treatment of 1 with H2 resulted in the cleavage of two molecules of H2 under concomitant formation of the corresponding trihydridodisilane and hydroborane. [ABSTRACT FROM AUTHOR]

Hexakis( tert-butyldimethylsilyl)bicyclo[1.1.0]tetrasilane ( 3), which is known to isomerize to the corresponding cyclotetrasilene 4above 0 °C, was synthesized via an alternative synthetic route and isolated at low temperatures as air-sensitive yellow crystals. The short-bond structure of 3was disclosed by X-ray analysis and DFT calculations, and facile ring flipping of 3below 0 °C with the activation parameters of Δ H‡= 6.67 ± 0.18 kcal mol −1and Δ S‡= −22.7 ± 0.8 cal mol −1K −1was observed. [ABSTRACT FROM AUTHOR]

A kinetic study of the thermal irreversible isomerization of an isolable dialkylsilylene into the corresponding cyclic silene revealed that the activation enthalpy (ΔH‡) and entropy (ΔS‡) are 18.49 ± 0.43 kcal mol−1and −20.32 ± 1.35 cal mol−1K−1, respectively. The relatively low ΔH‡and negative ΔS‡values are in accord with the concerted 1,2-silyl migration via a cyclic transition state as previously proposed. The cyclic silene in benzene-d6isomerized photochemically into the corresponding alkenylsilane via 1,3-hydrogen shift. [ABSTRACT FROM AUTHOR]