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Ligand modifications for tailoring the binuclear microenvironments in Schiff-base calixpyrrole pacman complexes
Elham Askarizadeh1, Aline M J Devoille, Davar M Boghaei
1EaStCHEM School of Chemistry, University of Edinburgh, Joseph Black Building, The King's Buildings, West Mains Road, Edinburgh EH9 3JJ, UK.
Inorganic Chemistry
|July 4, 2009
Summary
Researchers synthesized novel octadentate macrocycles, creating binuclear metal complexes with unique structural properties. Modifications influenced complex geometry and metal-metal interactions, impacting pyridine coordination modes.
Area of Science:
- Supramolecular Chemistry
- Coordination Chemistry
- Organic Synthesis
Background:
- Schiff-base macrocycles are versatile ligands in coordination chemistry.
- Calixpyrroles offer unique structural frameworks for complexation.
- Tuning macrocycle substituents can alter metal complex properties.
Purpose of the Study:
- To synthesize and characterize novel octadentate Schiff-base calixpyrrole macrocycles.
- To investigate the structural consequences of modifications in meso-substituents (L(1)) and aryl spacers (L(2)).
- To explore the formation and structures of binuclear metal complexes ([M(2)(L(1))] and [M(2)(L(2))]) derived from these macrocycles.
Main Methods:
- Synthesis of novel Schiff-base calixpyrrole macrocycles with varied substituents.
- Formation and isolation of binuclear palladium and cobalt complexes.
- Structural characterization using X-ray crystallography.
Main Results:
- Two new octadentate macrocycles, L(1) and L(2), were synthesized.
- Binuclear complexes [M(2)(L(1))] (M=Pd, Co) exhibited rigid, twisted geometries with constrained bimetallic microenvironments.
- The dicobalt complex [Co(2)(py)(2)(L(1))] showed an exo-exo-bonding mode for pyridine.
- Binuclear palladium complex [Pd(2)(L(2))] displayed cofacial PdN(4) environments, resembling cofacial diporphyrin complexes.
Conclusions:
- Macrocycle modifications significantly influence the geometry and microenvironment of binuclear metal complexes.
- The fluorenyl-meso-substitution leads to rigid, twisted structures with unique coordination behaviors.
- The anthracenyl backbone promotes cofacial arrangements, creating complexes analogous to diporphyrins.
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