RESUMO
While the chemistry of gold clusters has been developed rapidly, the knowledge of trinuclear gold clusters with low-valent gold remains scarce. Herein, we report the synthesis, structural characterization, and density functional theory (DFT) calculations of trinuclear anionic gold clusters 3a and 3b ligated by dialkylsilylene (1a) and dialkylgermylene (1b), respectively.
RESUMO
The bonding between gold and main-group metallic elements (M) featuring Auδ--Mδ+ 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'2Ge(AuPR3)(AuGeR'2) (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 pπ nature. A pendular motion of AuPR3 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- and electrophilic MeOTf reagents at Ge(II) and Ge(IV) centers, respectively.