A facile, one-pot synthesis of [Na(OC≡As)(dioxane) ] (x=2.3-3.3) in 78 % yield is reported through the reaction of arsine gas with dimethylcarbonate in the presence of NaO Bu and 1,4-dioxane. It has been employed for the synthesis of the first arsaketenyl-functionalized germylene [LGeAsCO] (2, L=CH[CMeN(Dipp)] ; Dipp=2,6- Pr C H ) from the reaction with LGeCl (1). Upon exposure to ambient light, 2 undergoes CO elimination to form the 1,3-digerma-2,4-diarsacyclobutadiene [L Ge As ] (3), which contains a symmetric Ge As ring with ylide-like Ge=As bonds. Remarkably, the CO ligand located at the arsenic center of 2 can be exchanged with PPh or an N-heterocyclic carbene NHC donor ( NHC=1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) to afford the novel germylidenylarsinidene complexes [LGe-AsPPh ] (4) and [LGe-As( NHC)] (5), respectively, demonstrating transition-metal-like ligand substitution at the arsinidene-like As atom. The formation of 2-5 and their electronic structures have been studied by DFT calculations.

A facile, one‐pot synthesis of [Na(OC≡As)(dioxane)x] (x=2.3–3.3) in 78 % yield is reported through the reaction of arsine gas with dimethylcarbonate in the presence of NaOtBu and 1,4‐dioxane. It has been employed for the synthesis of the first arsaketenyl‐functionalized germylene [LGeAsCO] (2, L=CH[CMeN(Dipp)]2; Dipp=2,6‐iPr2C6H3) from the reaction with LGeCl (1). Upon exposure to ambient light, 2 undergoes CO elimination to form the 1,3‐digerma‐2,4‐diarsacyclobutadiene [L2Ge2As2] (3), which contains a symmetric Ge2As2 ring with ylide‐like Ge=As bonds. Remarkably, the CO ligand located at the arsenic center of 2 can be exchanged with PPh3 or an N‐heterocyclic carbene iPrNHC donor (iPrNHC=1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene) to afford the novel germylidenylarsinidene complexes [LGe‐AsPPh3] (4) and [LGe‐As(iPrNHC)] (5), respectively, demonstrating transition‐metal‐like ligand substitution at the arsinidene‐like As atom. The formation of 2–5 and their electronic structures have been studied by DFT calculations.