Twisted push-pull disilenes obtained by direct 1,2-hydro/chloroborylation of a silylone.

Overcrowded 1-amino-2-boryldisilenes were isolated as blue crystals by the direct hydro/chloroborylation of a cyclic (alkyl)(amino)silylene-coordinated monatomic silicon complex (silylone) with 9-BBN (BBN = borabicyclo[3.3.1]nonane) hydride/chloride. The extreme twisting and push-pull effect around the SiSi bonds resulted in strong polarization of the SiSi bond. The disilenes exhibit longest-wavelength absorptions above 600 nm due to the charge-transfer-type π → π* transitions and undergo reversible 1,3-hydride/halide migration in solution reflecting the electrophilic terminal silicon atoms.