Synthesis, Electronic Structure, and Reactivity Studies of a 4-Coordinate Square Planar Germanium(IV) Cation

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• 作者：Huayi Fang ; Huize Jing ; Aixi Zhang ; Haonan Ge ; Zhengmin Yao ; Penelope J. Brothers ; Xuefeng Fu
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：June 22, 2016
• 年：2016
• 卷：138
• 期：24
• 页码：7705-7710
• 全文大小：442K
• 年卷期：0
• ISSN：1520-5126

文摘

A tetra-coordinate, square planar germanium(IV) cation [(TPFC)Ge]⁺ (TPFC = tris(pentafluorophenyl)corrole) was synthesized quantitatively by the reaction of (TPFC)Ge–H with [Ph₃C]⁺[B(C₆F₅)₄]^¯. The highly reactive [(TPFC)Ge]⁺ cation reacted with benzene to form phenyl complex (TPFC)Ge–C₆H₅ through an electrophilic pathway. The key intermediate, a σ-type germylium-benzene adduct, [(TPFC)Ge(η¹-C₆H₆)]⁺, was isolated and characterized by single-crystal X-ray diffraction. Deprotonation of [(TPFC)Ge(η¹-C₆H₆)]⁺ cation led to the formation of (TPFC)Ge–C₆H₅. [(TPFC)Ge]⁺ also reacted with ethylene and cyclopropane in benzene at room temperature to form (TPFC)Ge–CH₂CH₂C₆H₅ and (TPFC)Ge–CH₂CH₂CH₂C₆H₅, respectively. The observed electrophilic reactivity is ascribed to the highly exposed cationic germanium center with novel frontier orbitals comprising two vacant sp-hybridized orbitals that are not conjugated to π-system. The three electron-withdrawing pentafluorophenyl groups on the corrole ligand also enhance the electrophilicity of the cationic germanium corrole.