Facile Access to NaOCAs and Its Use as an Arsenic Source To Form Germylidenylarsinidene Complexes

A facile, one-pot synthesis of [Na(OCAs)(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 Asatom. The formation of 2-5 and their electronic structures have been studied by DFT calculations.