The Binary Group 4 Azides [PPh₄ ]₂ [Zr(N₃ )₆ ] and [PPh₄ ]₂ [Hf(N₃ )₆ ].

Area of Science:

• Inorganic Chemistry
• Materials Science
• Computational Chemistry

Background:

• Polyazido metal complexes are of interest due to their unique bonding and potential applications.
• Zirconium and hafnium azides have not been extensively studied.

Purpose of the Study:

• To synthesize and characterize novel binary zirconium and hafnium polyazides.
• To investigate the coordination environment of metal azides in these compounds.
• To computationally study related azido species.

Main Methods:

• Fluoride-azide exchange reactions using trimethylsilyl azide (Me3SiN3) and tetraphenylphosphonium azide ([PPh4][N3]).
• Characterization using vibrational spectroscopy and X-ray crystallography.
• Quantum chemical calculations (Density Functional Theory and MP2 levels).

Main Results:

• Near quantitative yields of [PPh4]2[M(N3)6] (M=Zr, Hf) were achieved.
• X-ray crystal structures confirmed the polyazido nature and revealed near-linear M-N-N coordination.
• Computational studies explored [M(N3)4], [M(N3)5]−, and [M(N3)6]2− for M=Ti, Zr, Hf.

Conclusions:

• The successful synthesis and characterization of novel zirconium and hafnium polyazides.
• Experimental evidence supports near-linear metal azide coordination geometries.
• Computational methods provide further insights into the electronic structure of related azido species.