Events & Seminars > Event Details

Where:

4:00pm
Room 304, Chemistry Building

Beyond The Periodic Table: Role of Superatoms

Speaker:

Professor Puru Jena
Virginia Commonwealth University

Hosted by: Professor John T. Yates, Jr.

Nearly twenty years ago it was predicted that stable atomic clusters with specific size and composition and mimicking the chemistry of atoms in the periodic table can be designed and synthesized [1]. These clusters known as “superatoms” can then form the building blocks of a new three-dimensional periodic table and the basis for cluster assembled materials. This talk will outline the considerable progress [2] that has been made over the years by focusing on one class of “superatoms” called “superhalogens”. These consist of a metal atom at the core surrounded by halogen atoms and have electron affinities far exceeding the value of chlorine. Because of their high electron affinities, superhalogens almost always exist as negative ions, usually as the anionic portions of salts. While past studies have revealed many such molecules like permanganates (MnO4) and perchlorates (ClO4), many more are waiting to be discovered.       

I will demonstrate how an entirely new class of superhalogens with unusual composition and properties can be designed and synthesized by using simple electron counting rules, such as the octet, 18-electron, and Wade-Mingos rule. Discovery of negative ions [3] with electron affinities even higher than those of superhalogens will be presented. These species referred to as hyperhalogens are formed when a metal atom is surrounded by superhalogen moieties, instead of halogen atoms. The role of super and hyperhalogens in promoting unusual chemistry and forming novel salts will be discussed. The results are obtained through a synergy between first principles theory and photoelectron spectroscopy experiments.

[1] Khanna, S.N. and Jena, P.: On Assembling Crystals from Clusters, Phys. Rev. Lett. 69, 1664 (1992); Khanna, S.N., and Jena, P.: Atomic Clusters: Building Blocks for a Class of Solids, Phys. Rev. B. 51, 13705 (1995).

[2] Jena, P.: “Beyond the Periodic Table of Elements: The Role of Superatoms”, J. Phys. Chem. Letters 4, 1432 (2013)

[3] Willis, M., Gotz, M., Kandalam, A. K., Gantefor, G, and Jena, P.: “Hyperhalogens: Discovery of a New Class of Electro-negative Species“, Angew. Chem. Int. Ed. 49, 8966 (2010)

Professor Jena’s webpage