Precise Activation of Ammonia and Carbon Dioxide by an Iminodisilene

The activation of NH₃ and CO₂ is still an ambitious target for multiply bonded sub-valent silicon compounds. Now, the precise splitting of the N−H bond of ammonia by (Z)-imino(silyl)disilene 1 to give trans-1,2-adduct 2 a at low temperatures (−78 °C) is presented. According to DFT calculations, the stereospecific hydroamination follows a similar mechanism as the recently reported anti-addition of H₂ to the Si=Si bond of 1. The aminosilane 2 b could also be obtained as the formal silylene addition product under thermodynamic reaction control. By applying low temperatures, the activation of CO₂ with 1 selectively afforded the cis-oxadisilacyclobutanone 7-c as [2+2] cycloadduct. By performing the reaction directly at ambient temperatures, a mixture of three different-sized silacycles (4–6) was observed. Their formation was investigated theoretically and their structures were revealed with separate experiments using 1 and the oxygenation agents N₂O and O₂.