Macrocyclic Heterodinuclear Zn(II)Pb(II) Complexes: Synthesis, Structures, and Hydrolytic Function toward...

Area of Science:

• Coordination Chemistry
• Supramolecular Chemistry
• Catalysis

Background:

• Synthesis and characterization of novel heterodinuclear metal complexes are crucial for developing new catalysts.
• Macrocyclic ligands offer unique coordination environments for metal ions, influencing their reactivity.
• Understanding the structural and electronic properties of metal complexes is key to predicting their catalytic behavior.

Purpose of the Study:

• To synthesize and characterize a novel heterodinuclear zinc(II)lead(II) complex with an unsymmetric macrocyclic ligand.
• To investigate the structural features and coordination geometry of the synthesized complex and its derivatives.
• To explore the catalytic activity of the complex in the hydrolysis of tris(p-nitrophenyl) phosphate (TNP).

Main Methods:

• Heterodinuclear complex synthesis via condensation reactions.
• Single-crystal X-ray diffraction for structural determination.
• Spectroscopic techniques (31P NMR, visible spectra) for mechanistic studies.

Main Results:

• A heterodinuclear Zn(II)Pb(II) complex, ZnPb(L)(ClO4)2.2H2O (1), was synthesized and characterized.
• Complex 1 converts to a dimeric hydroxide-bridged species [ZnPb(L)(OH)]2(2+) (2) under alkaline conditions.
• Complex 2 effectively catalyzes the hydrolysis of TNP to BNP in DMSO, with a proposed mechanism involving Pb-bound TNP and Zn-bound hydroxide.
• A bis(p-nitrophenyl) phosphate (BNP) complex, [ZnPb(L)(BNP)]ClO4 (3), was isolated from the reaction mixture.

Conclusions:

• The synthesized heterodinuclear Zn(II)Pb(II) macrocyclic complex exhibits interesting structural properties and catalytic activity.
• The dimeric hydroxide-bridged complex acts as an efficient catalyst for TNP hydrolysis.
• A plausible mechanism for TNP hydrolysis has been elucidated, highlighting the cooperative role of the metal centers and the hydroxide bridge.