Experimental evidence of chalcogen bonding at oxygen

Abstract

An o-nitro-O-Aryl oxime was observed to exhibit a short O⋯O contact, which exhibited characteristics consistent with a chalcogen bond. The O-N bond length of the oxime was appreciably longer than the expected value, and NBO calculations indicated the presence of a n(O) → (O-N) orbital delocalisation. Topological analysis of the experimental electron density of two analogues shows the presence of a bond path between the two oxygen atoms, with (r) and 2(r) values consistent with an electrostatic interaction. Finally, electrostatic potential calculations indicate the presence of a-hole, the "smoking gun" indicating a Ch-bond. These results are unusual as oxygen is not typically considered to be..