Azide addition to give a tetra-azazirconacycle complex

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Synthetic Inorganic Chemistry

Background:

• Zirconium tetrachloride (ZrCl4) is a common precursor in organometallic synthesis.
• Ortho-phenylenediamine ligands offer unique coordination possibilities due to their proximity of nitrogen atoms.
• The development of novel metal complexes with specific ligand architectures is crucial for exploring new reactivity.

Purpose of the Study:

• To synthesize and characterize a novel base-free zirconium complex with planar ortho-phenylenediamine ligands.
• To investigate the reactivity of the synthesized zirconium complex with donor ligands and organic azides.
• To elucidate the structure of the resulting metallacycle complex.

Main Methods:

• Addition of dilithium salt, ortho-(Me3SiNLi)2C6H4, to ZrCl4.
• Coordination of donor ligands (e.g., NHEt2) to the zirconium complex.
• Reaction of zirconium complexes with aryl azides.
• X-ray crystallography for structural determination of the tetra-azametallacycle.

Main Results:

• A base-free, D2d-symmetric Zr(IV) complex, Zr(IV)[ortho-(Me3SiN)2C6H4]2, was synthesized with planar diamine ligands.
• The zirconium complex readily formed a five-coordinate complex upon coordination of donor ligands.
• Reaction with aryl azides yielded an unusual tetra-azametallacycle complex via N-Si bond addition, characterized by X-ray crystallography.

Conclusions:

• The synthesized zirconium complex exhibits unique reactivity, particularly with organic azides.
• The formation of the tetra-azametallacycle demonstrates a novel reaction pathway involving N-Si bond activation.
• The study expands the understanding of zirconium coordination chemistry and its potential in organic transformations.