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Researchers create bonds between two unlikely pairs

Recent research from the research groups of Professor Connie Lu & Professor Laura Gagliardi

A joint paper by the research groups of Professor Connie Lu and Professor Laura Gagliardi showcases a new type of bonding between aluminum(III) ions and transition metal elements. The work was recently published in Journal of the American Chemical Society.

Bonds between transition metals and Group 13 main group ions are fundamentally interesting because the metal and ligand roles are reversed to form a covalent bond. The metal acts as the Lewis base, donating its electrons to a Lewis acidic ligand, e.g. borane. To study this unusual bonding, inorganic chemists have made many complexes with M→B(III) interactions, also known as metallaboratranes. Surprisingly, very few examples the M→Al(III) counterparts, aka metallalumatranes, exist.

To prepare these elusive compounds, Alex Rudd, a graduate student in the Lu group, developed a multidentate ligand that is designed to stabilize an Al(III) ion in bonding proximity to a transition metal center. The Al(III) ion is inserted first into the ligand scaffold, creating a synthon for building M→Al(III) bonds. The modular synthetic methodology has given access to previously unknown Ni→Al(III) and Co→Al(III) bonds and to the second example of an Fe→Al(III).

Shengsi "Mike" Liu, an undergraduate student in the Gagliardi group, performed density functional theory (DFT) calculations to understand the nature of these M→Al(III) bonds. His studies allowed the researchers to visualize the frontier orbitals and to interpret the excitations of these compounds.

The team is now focused on the next challenge: developing these systems to activate small-molecules such as dinitrogen and carbon dioxide.

This work can be read at

Part of this work was featured on the Eye on Earth blog hosted by the University of Minnesota's Institute on the Environment.