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

J Am Chem Soc. 2016 Jun 22;138(24):7705-10. doi: 10.1021/jacs.6b03547. Epub 2016 Jun 10.

Abstract

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(η(1)-C6H6)](+), was isolated and characterized by single-crystal X-ray diffraction. Deprotonation of [(TPFC)Ge(η(1)-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.

Publication types

  • Research Support, Non-U.S. Gov't