Anomalous Electronic Properties of Iodous Materials: Application to High-Spin Reactive Intermediates and Conjugated Polymers

Manipulating frontier orbital energies of aromatic molecules with substituents is key to a variety of chemical and material applications. Here, we investigate a simple strategy for achieving high-energy in-plane orbitals for aromatics simply by positioning iodine atoms next to each other. The lone pair orbitals on the iodines mix to give a high-energy in-plane σ-antibonding orbital as the highest occupied molecular orbital (HOMO). We show that this effect can be used to manipulate orbital gaps, the symmetry of the highest occupied orbital, and the adopted electronic state for reactive intermediates. This electronic effect is not limited to reactive intermediates, and we demonstrate that this iodine buttressing strategy also can be used to achieve small HOMO-lowest unoccupied molecular orbital (HOMO-LUMO) gaps in organic electronic materials. Iodinated oligomers of several of the most popular conducting polymers are computed to have smaller HOMO-LUMO gaps than the unsubstituted materials. This iodine buttressing approach for generating high-energy in-plane HOMOs is anticipated to be highly general. While the unusual properties of fluorous materials are well established, at the other extreme on the periodic table novel properties of iodous materials may await discovery.