This paper describes the synthesis and characterization of a new structurally interesting polybismuthide. The bonding is understood through band structure calculations and a retrotheoretical approach, analyzing the interactions of smaller substructures. Discussion is focused on the Ga-Ga bonding interactions and the weaker Ga-Bi and Bi-Bi interactions within the one-dimensional bismuth ribbons. This is a nice illustration of what a chemist can learn from the band structures of an extended solid and exposes students to an interesting combination of elements in the periodic table that are often overlooked.
I teach the essentials of band theory for extended solids using the text by Roald Hoffmann, "Solids and Surfaces: A Chemist's View of Bonding in Extended Structures." Band theory builds nicely upon any advanced discussion of molecular orbital theory. We discussed this paper after covering most of the Hoffmann text, and it served as a nice illustration of many of the principles of band theory, including understanding the physical properties of the material (in this case, metallic conducitivity).
Student performance on the discussion questions is assessed.
Often students have trouble even thinking about assigning reasonable formal oxidation states for these elements.
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