Frustrated Lewis Pairs from Al-E^{14} Bonds (E^{14}=Ge, Sn, Pb)

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Main Group Chemistry

Background:

• Aluminum-Ge, -Sn, and -Pb compounds are of interest due to their unique bonding and reactivity.
• The synthesis and characterization of unsupported Al-E bonds are challenging.
• Frustrated Lewis pairs (FLPs) are reactive species capable of small molecule activation.

Purpose of the Study:

• To synthesize and characterize novel Lewis pairs featuring unsupported Al-E bonds.
• To investigate the reactivity of these Lewis pairs with small molecules like CO2 and ethene.
• To explore the formation and reactivity of Al-E based frustrated Lewis pairs.

Main Methods:

• Synthesis of potassium aluminyl and group 14 chloroamidinates.
• Spectroscopic analysis (NMR, UV-vis, Mössbauer) and X-ray diffraction.
• Computational studies including DFT, QTAIM, and TD-DFT.

Main Results:

• Formation of (NON)Al-E{14}(Am) Lewis pairs with unsupported Al-E bonds (E=Ge, Sn, Pb), including the first characterized Al-Pb bond.
• Characterization of Al-E bonds as σ-bonds with significant back-donation from E to Al.
• Reactions with CO2 yielded dioxocarbene and carbonate complexes, while ethene formed FLPs, which further reacted with CO2 and diisopropylcarbodiimide.

Conclusions:

• The study successfully synthesized and characterized unprecedented Al-E Lewis pairs and FLPs.
• The findings provide fundamental insights into the bonding and reactivity of Al-E bonds.
• The reported compounds demonstrate versatile reactivity towards small molecules, opening avenues for new chemical transformations.