Facile Access to NaOC≡As and Its Use as an Arsenic Source To Form Germylidenylarsinidene Complexes

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 NaO^tBu and 1,4-dioxane. It has been employed for the synthesis of the first arsaketenyl-functionalized germylene LGeAsCO] ( 2 , L=CHCMeN(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.