Structure and reactivity of germylene-bridged digold complexes.

Wang, Liliang; Zhen, Guorong; Li, Yinhuan; Kira, Mitsuo; Yan, Liping; Chang, Xiao-Yong; Huang, Lu; Li, Zhifang · Nat Commun · 2022

basic_science · Level V

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Abstract

The bonding between gold and main-group metallic elements (M) featuring Au<sup>δ-</sup>-M<sup>δ+</sup> polarity, has been studied recently. The gold in the bonds is expected to have the oxidation number of -1, and hence, nucleophilic. However, the knowledge of the reactivity of the gold-metal bonds remains limited. Here, we report digold-substituted germanes of the form of R'<sub>2</sub>Ge(AuPR<sub>3</sub>)(AuGeR'<sub>2</sub>) (3a; R = Me, 3b; R = Et), featuring two Au-Ge(IV) and one Au-Ge(II) bonds. DFT calculations of 3a revealed the existence of high-lying σ(Ge-Au) type HOMO and low-lying LUMO with germylene p<sub>π</sub> nature. A pendular motion of AuPR<sub>3</sub> group between Ge(IV) and Ge(II) of 3 occurs in the NMR time scale, suggesting that the Ge(II) center has an enhanced electrophilicity to be attacked by the nucleophilic gold (-I) atom. 3a reacts with nucleophilic Cl<sup>-</sup> and electrophilic MeOTf reagents at Ge(II) and Ge(IV) centers, respectively.