Unexpected “amphoteric” character of the halogen bond: the charge density study of the co-crystal of N-methylpyrazine iodide with I2

Abstract

An unexpected mechanism of halogen bonding that cannot be rationalized within the accepted σ-hole model was found in the co-crystal of N-methylpyrazine iodide with molecular iodine via the topological analysis of the electron density distribution derived from the high-resolution X-ray diffraction data.