Activity: Lecture and oral contribution
Jens Spanget-Larsen - Lecturer, 9 Mar 2012
Lecture at the Department of Science, Systems and Models, Roskilde University
The formation of a so-called Charge Transfer (CT) complex between pyridine and iodine is a classical example of 'halogen bonding' and has been the subject of numerous studies. However, when we investigated the reaction with polyethylene as a solvent, we found that the main product was not the expected pyridine-iodine CT complex. Rather, the main product turned out to be a salt, i.e., an ion pair. The salt formation was found to be strongly favoured in stretched polyethylene. The product is probably N-iodopyridinium triiodide or bis(pyridine)iodonium triiodide. The spontaneous formation of ions in a non-polar medium like polyethylene is quite unusual. The reason for the phenomenon is not yet fully understood.