A Mystery in Hexaiodobenzene
October 7th, 2007 by mitch
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A mystery for the Chemical Illuminati.
Many years ago, I synthesized hexaiodobenzene as a reagent for some Sonogashira reactions I was exploring. After crystallizing the product out of solution, I began filtering the gorgeous orange-red crystals. As my attention span is small, I also began refilling my manifold traps with liquid nitrogen. Some of the liquid nitrogen splashed onto the filtering hexaiodobenzene crystals and instantly turned yellow-orange. As the vial heats up it will reversibly return to its red-orange color. A video of the process is shown below: Or click me for direct link.
Color Change In HexaiodobenzeneI’ve always wondered what caused the color change, as I’m unfamiliar if this is a common phenomenon. The only two-three reasonable explanations I can think of are: 1.) N2 is complexing into the aromatic ring somehow 2.) Some sort of solid-solid phase transition is occurring 3.) Changing temperatures caused the relative energies of it’s Homo-Lumo gap to change by some mechanism. If you have any thoughts, or thoughtful ideas on what can be done to sort out this mystery lets hear them. Perhaps the Carbon-Based Curiosities will enlighten me. Mitch |
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