Coordinated nitrate anions can be directional π-hole donors in the solid state: a CSD study

A comprehensive Cambridge Structure Database evaluation reveals grouping and significant van der Waals overlap of sp(2) O-atoms above/below the N-atom of coordinated nitrate anions. Overlap of van der Waals shells increases with increased coordination and 84% of close contacts involve anti-electrostatic NO3-center dot center dot center dot NO3- interactions.