Stable Push–Pull Disilene: Substantial Donor–Acceptor Interactions through the SiSi Double Bond

The push–pull effect has been widely used to effectively tune π-electron systems. Herein, we report the synthesis and properties of 1-amino-2-boryldisilene <b>1</b> 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 π → π* absorption band of <b>1</b> is remarkably red-shifted compared to that of the corresponding alkyl-substituted disilene <b>2</b>. Treatment of <b>1</b> with H₂ resulted in the cleavage of two molecules of H₂ under concomitant formation of the corresponding trihydridodisilane and hydroborane

Pentasila-1,4-diene: Homoconjugation between SiSi Double Bonds via a SiMe₂ Unit

Although the synthesis of several bis­(disilenes) has already been reported, the number of reported conjugation modes between the SiSi double bonds remains limited. Herein, we report the properties of the stable pentasila-1,4-diene <b>1</b>, which was obtained from the reaction of two equivalents of disilenide <b>4</b> with dichlorodimethylsilane. The π­(SiSi)→π*­(SiSi) absorption band of <b>1</b> is considerably broadened and red-shifted compared to those of the corresponding monodisilene and hexasila-1,5-diene, but blue-shifted relative to those of typical tetrasila-1,3-dienes. The bathochromic shift and the broadening of the absorption band in <b>1</b> should be attributed to the homoconjugation between SiSi double bonds through the SiMe₂ unit