Acyclic Germylones: Congeners of Allenes with a Central Germanium Atom

作者：Li, Yan; Mondal, Kartik Chandra; Roesky, Herbert W.^*; Zhu, Hongping; Stollberg, Peter; Herbst-Irmer, Regine; Stalke, Dietmar; Andrada, Diego M.

来源：Journal of the American Chemical Society, 2013, 135(33): 12422-12428.

DOI：10.1021/ja406112u

• DIVALENT CARBON(0) COMPOUNDS
• PLANAR NICKEL-COMPLEXES
• THEORETICAL EVIDENCE
• DIRADICAL CHARACTER
• CORRELATION-ENERGY
• AB-INITIO
• DENSITY
• SILICON(0)
• CARBODICARBENES
• APPROXIMATION

The cyclic alkyl(amino) carbene (cAAC:)-stabilized acyclic germylones (Me-2-cAAC:)(2)Ge (1) and (Cy-2-cAAC:)(2)Ge (2) were prepared utilizing a one-pot synthesis of GeCl2(dioxane), cAAC:, and KC8 in a 1:2:2.1 molar ratio. Dark green crystals of compounds 1 and 2 were produced in 75 and 70% yields, respectively. The reported methods for the preparation of the corresponding silicon compounds turned out to be not applicable in the case of germanium. The single-crystal X-ray structures of 1 and 2 feature the C-Ge-C bent backbone, which possesses a three-center two-electron pi-bond system. Compounds 1 and 2 are the first acyclic germylones containing each one germanium atom and two cAAC: molecules. EPR measurements on compounds 1 and 2 confirmed the singlet spin ground state. DFT calculations on 1/2 revealed that the singlet ground state is more stable by similar to 16 to 18 kcal mol(-1) than that of the triplet state. First and second proton affinity values were theoretically calculated to be of 265.8 (1)/267.1 (2) and 180.4 (1)/183.8 (2) kcal mol(-1), respectively. Further calculations, which were performed at different levels suggest a singlet diradicaloid character of 1 and 2. The TD-DFT calculations exhibit an absorption band at similar to 655 nm in n-hexane solution that originates from the diradicaloid character of germylones 1 and 2.

• 出版日期2013-8-21
• 单位厦门大学