Reactivity of Tetrel-Functionalized Heptaphosphane Clusters toward Azides

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Materials Science

Background:

• Phosphorus clusters, particularly Zintl clusters, are versatile building blocks in inorganic chemistry.
• Functionalization of these clusters is crucial for developing new materials and understanding their reactivity.
• Tetrel elements (Si, Ge) are often used to stabilize and functionalize phosphorus clusters.

Purpose of the Study:

• To investigate the reactivity of tetrel-functionalized phosphorus clusters with organoazides.
• To explore the insertion mechanism of organoazide units into phosphorus-tetrel bonds.
• To synthesize and characterize novel Zintl clusters functionalized with exo-nitrogen-bonded moieties.

Main Methods:

• Reaction of tetrel-functionalized phosphorus clusters ((Me3Si)3P7 and (Me3Ge)3P7) with various organoazides (benzyl azide, phenyl azide, 4-bromophenyl azide).
• Stoichiometric control to observe mono-, bis-, and tris-inserted products.
• Computational chemistry to investigate the bonding and electronic properties of the functionalized clusters.

Main Results:

• Organoazide units ([RN]) were found to insert into the phosphorus-tetrel bonds of the clusters, with elimination of nitrogen gas (N2).
• Stepwise insertion was confirmed by observing mono-, bis-, and tris-inserted products through controlled stoichiometry.
• Computational studies indicated a formal oxidation of the phosphorus cluster upon amine moiety bonding.

Conclusions:

• The reaction offers a convenient and novel method for synthesizing Zintl clusters functionalized with exo-nitrogen-bonded moieties.
• These functionalized clusters were previously unknown and expand the scope of Zintl cluster chemistry.
• The findings highlight the utility of organoazides as reagents for modifying phosphorus cluster frameworks.