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Published on: April 19, 2019
Aryl-NHC-group 13 trimethyl complexes: structural, stability and bonding insights
Melissa M Wu1, Arran M Gill2, Lu Yunpeng1
1School of Physical and Mathematical Sciences, Division of Chemistry and Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore. Fgarcia@ntu.edu.sg.
New Lewis acid-base adducts of N-heterocyclic carbenes (NHCs) with gallium and indium were synthesized. Their stability depends on NHC ligand structure, quantified by steric analyses and bond energy decomposition.
Area of Science:
- Organometallic Chemistry
- Coordination Chemistry
- Materials Science
Background:
- N-heterocyclic carbenes (NHCs) are versatile ligands in organometallic chemistry.
- Gallium and indium compounds exhibit interesting Lewis acidic properties.
- Understanding the stability of metal-ligand adducts is crucial for catalyst design.
Purpose of the Study:
- To synthesize and characterize new Lewis acid-base adducts of NHCs with trimethylgallium and trimethylindium.
- To investigate the influence of NHC ligand structure on the stability of these adducts.
- To quantify steric and electronic factors governing the M-NHC bond interactions.
Main Methods:
- Synthesis of eight novel NHC-metal adducts (M = Ga, In).
- Characterization using X-ray diffraction, IR, and multinuclear NMR spectroscopy.
- Quantification of steric effects using percent buried volume (%VBur) and topographic steric maps.
- Bond snapping energy (BSE) decomposition analysis.
Main Results:
- Successful synthesis and full characterization of eight Lewis acid-base adducts.
- Complex stability is strongly correlated with the steric bulk of the NHC ligands.
- %VBur and steric maps effectively explain the observed stability trends.
- BSE analysis provided insights into steric and orbital contributions to M-NHC bonding.
Conclusions:
- The steric properties of NHC ligands are critical determinants of adduct stability with group 13 metals.
- This study provides a quantitative understanding of steric and electronic effects in NHC-metal complexes.
- The findings can guide the rational design of novel organometallic compounds with tailored properties.
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