A dialkylgermanone (R₂Ge=O) was synthesized and isolated as a THF-coordinated form. The reaction of the THF-coordinated dialkylgermanone with triphenylphosphine affording the corresponding germylene and triphenylphosphine oxide indicated that the Ge=O bond in the THF-coordinated germanone is weaker than the P=O bond in triphenylphosphine oxide. The reaction with a phosphaylide provided a Ge=C compound, which represents the first germa-Wittig reaction.

Abstract

A stable dialkylgermanone was generated by mixing a solid of the corresponding dialkylgermylene and gaseous N₂O. While the dialkylgermanone is marginally persistent in solution and gradually converts to its head-to-tail dimer at room temperature, the addition of THF to the dialkylgermanone provided an isolable THF-coordinated dialkylgermanone. The THF-coordinated dialkylgermanone reacts with H₂O, THF, and B(C₆F₅)₃ similar to the corresponding base-free two-coordinate dialkylsilanone. The dialkylgermanone undergoes deoxygenation in the presence of triphenylphosphine to provide the corresponding germylene and olefination upon treatment with phosphaylide Ph₃PCHPh to afford the corresponding Ge=C bond compound (germa-Wittig reaction).