Quantifying the Donor Strength of Ligand-Stabilized Main Group Fragments
Leon Maser1, Christian Schneider1, Lisa Vondung1
1Department of Chemistry , Philipps-Universität Marburg , Hans-Meerwein-Str. 4 , 35032 Marburg , Germany.
Journal of the American Chemical Society
|April 19, 2019
Summary
Ligand-stabilized main group fragments, like boron and carbon compounds, exhibit strong donor properties. This study quantifies their binding strength, aiding homogeneous catalysis research.
Area of Science:
- Coordination Chemistry
- Organometallic Chemistry
- Homogeneous Catalysis
Background:
- Ligand-stabilized main group fragments (e.g., carbodiphosphoranes, carbenes) show promise for stabilizing elusive species and in homogeneous catalysis.
- Quantifying and comparing the binding properties of these fragments experimentally remains a significant challenge.
Purpose of the Study:
- To quantify and compare the donor strength of central donor groups (E) in iridium(III) pincer complexes.
- To investigate the electronic properties of phosphine-stabilized boron(I) and carbon(0) compounds as neutral donor ligands.
Main Methods:
- Synthesis and characterization of iridium(III) pincer complexes of the type [(PEP)IrCl(CO)(H)]^q (q = 0, +1, +2).
- Experimental quantification of donor strengths.
- Quantum chemical calculations to support experimental findings and explore heavier homologues.
Main Results:
- Phosphine-stabilized boron(I) and carbon(0) compounds function as exceptionally strong neutral donor groups.
- These novel ligands demonstrate superior donor strength compared to common spectator ligands like carbenes and phosphines.
- The study provides the first experimental and computational basis for comparing the donor strength of cationic, neutral, and anionic ligands.
Conclusions:
- Ligand-stabilized boron and carbon fragments are potent neutral donors, valuable for homogeneous catalysis.
- Heavier analogues of these phosphine-stabilized borylenes and carbon compounds exhibit slightly reduced donor properties.
- This work advances the understanding and application of main group elements in coordination chemistry and catalysis.
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