A Monoanionic Arsenide Source: Decarbonylation of the 2‐Arsaethynolate Anion upon Reaction with Bulky Stannylenes

We report fundamental studies on the reactivity of the 2‐arsaethynolate anion (AsCO − ), a species that has only recently become synthetically accessible. The reaction of AsCO − with the bulky stannylene Ter 2 Sn (Ter=2,6‐bis[2,4,6‐trimethylphenyl]phenyl) is described, which leads to the unexpected formation of a [Ter 3 Sn 2 As 2 ] − cluster compound. On the reaction pathway to this cluster, several intermediates were identified and characterized. After the initial association of AsCO − to Ter 2 Sn, decarbonylation occurs to give an anion featuring monocoordinate arsenic, [Ter 2 SnAs] − . Both species are not stable under ambient conditions, and [Ter 2 SnAs] − rearranges to form [TerSnAsTer] − , an unprecedented anionic mixed Group 14/15 alkene analogue.