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A pentanuclear lead(II) complex based on a strapped porphyrin with three different coordination modes
Stéphane Le Gac1, Eric Furet, Thierry Roisnel
1Institut des Sciences Chimiques de Rennes, UMR 6226, CNRS - Ecole Nationale Supérieure de Chimie de Rennes-Université de Rennes 1 , F-35042 Rennes Cedex, France.
Inorganic Chemistry
|September 12, 2014
Summary
This study reveals how lead(II) and bismuth(III) ions self-assemble into complex structures using strapped porphyrins. The lone pair of electrons on lead(II) influences its coordination and assembly behavior.
Area of Science:
- Coordination Chemistry
- Supramolecular Chemistry
- Materials Science
Background:
- Bimetallic complexes with strapped porphyrins exhibit unique coordination modes.
- The "hanging-atop" (HAT) metal ion coordination sphere in lead(II) complexes allows for additional ligand binding and intermolecular interactions.
- Previous work established Pb(II) and Bi(III) complexes with out-of-plane (OOP) and HAT coordination.
Purpose of the Study:
- To investigate the self-assembly of a pentanuclear lead(II) complex with strapped porphyrins.
- To characterize the different coordination modes of lead(II) ions within the complex.
- To explore the role of the stereochemically active lone pair on lead(II) in supramolecular assembly.
Main Methods:
- Synthesis and structural characterization of a pentanuclear lead(II) complex.
- X-ray crystallography to determine coordination modes and complex structure.
- Density Functional Theory (DFT) calculations to analyze electronic properties and lone pair behavior.
Main Results:
- A pentanuclear lead(II) complex was synthesized, displaying three distinct coordination modes.
- The HAT lead(II) ions coordinate additional acetate ligands, facilitating self-assembly.
- DFT calculations confirmed electron-density pockets associated with stereochemically active lone pairs on HAT lead(II) atoms.
- The "volume" of the lone pair correlates with coordination number and proximal oxygen atoms, following the order Bi(III) > Pb(II) (6-coordinate) > Pb(II) (5-coordinate).
Conclusions:
- The stereochemically active lone pair on HAT lead(II) plays a crucial role in the self-assembly of these supramolecular architectures.
- The coordination behavior of post-transition metals in strapped porphyrin systems is influenced by their electronic structure and coordination environment.
- This study provides insights into the design principles for constructing complex metal-organic frameworks using porphyrin ligands.
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