Structure and reactivity of germylene-bridged digold complexes

Area of Science:

• Organometallic Chemistry
• Main-Group Chemistry
• Gold Chemistry

Background:

• Recent studies investigate gold-main group metal bonds (Au-M) with Auδ−-Mδ+ polarity.
• Gold's expected nucleophilic nature (oxidation state -1) in these bonds is known, but reactivity is poorly understood.

Purpose of the Study:

• To synthesize and characterize novel digold-substituted germanes.
• To investigate the electronic structure and bonding in these compounds.
• To explore the reactivity of gold-germanium bonds.

Main Methods:

• Synthesis of digold-substituted germanes (R'2Ge(AuPR3)(AuGeR'2)).
• Density Functional Theory (DFT) calculations to analyze electronic structure (HOMO/LUMO).
• Nuclear Magnetic Resonance (NMR) spectroscopy to observe dynamic behavior.

Main Results:

• Reported synthesis of digold-substituted germanes with Au-Ge(IV) and Au-Ge(II) bonds.
• DFT revealed high-lying σ(Ge-Au) HOMO and low-lying LUMO with germylene pπ character.
• NMR indicated dynamic exchange of the AuPR3 group, suggesting electrophilic Ge(II) sites.

Conclusions:

• The synthesized germanes exhibit unique bonding and electronic properties.
• The Ge(II) center demonstrates enhanced electrophilicity, facilitating reactions with nucleophilic gold.
• Selective reactions at Ge(II) and Ge(IV) centers with different reagents were observed.