title: The first observation of nitrogen-carbonyl bonding: self-assembly of N-oxalyl 2,4-dinitroanilide assisted by a weak N...O=C interaction.
abstract: A new type of weak bond, i.e., the N...O=C interaction, that determines the crystal packing of N-oxalyl 2,4-dinitroanilide (1) in cooperation with C-H...O hydrogen bonds, has been found and is rationalized by ab initio calculations as being the result of electrostatic interactions.