Unprecedented Formation of a Binuclear Au(II)-Au(II) Complex through Redox State Cycling: Electrochemical Interconversion of Au(I)-Au(I), Au(II)-Au(II), and Au(I)-Au(III) in Binuclear Complexes Containing the Carbanionic Ligand C6F4PPh2

Chencheng Sun, Nedaossadat Mirzadeh, Si Xuan Guo, Jiezhen Li, Zhengkui Li, Alan M. Bond, Jie Zhang, Suresh K. Bhargava

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Abstract

The rational design of binuclear Au(I)-Au(I), Au(II)-Au(II), and Au(I)-Au(III) complexes requires an understanding of how the redox states interconvert. Herein, the electrochemical interconversion of the three oxidation states I, II, and III is reported on the voltammetric (cyclic and rotating disk electrode) time scales for binuclear gold complexes containing C6F4PPh2 as a ligand, to demonstrate for the first time formation of a binuclear Au(II)-Au(II) from a Au(I)-Au(III) complex. Results are supported by bulk electrolysis and coulometry with reaction products being identified by 31P NMR and UV-vis spectroscopy. All electrochemical processes involve an overall two-electron charge-transfer process with no one-electron intermediate being detected. Importantly, the kinetically rather than thermodynamically favored isomer [Au2 IIX2(μ-2-C6F4PPh2)2] is formed on redox cycling of [XAuI(μ-2-C6F4PPh2)(κ2-2-C6F4PPh2)AuIIIX] (X = Cl, ONO2). Finally, a mechanism is proposed to explain the simultaneous change of coordination of the chelating carbanionic ligand to bridging mode and interconversion of oxidation states in binuclear gold complexes.

Original languageEnglish
Pages (from-to)13999-14004
Number of pages6
JournalInorganic Chemistry
Volume58
Issue number20
DOIs
Publication statusPublished - 1 Oct 2019

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