Variable temperature neutron diffraction analysis of a very short O-H;⋯O hydrogen bond in 2,3,5,6-pyrazinetetracarboxylic acid dihydrate: Synthon-assisted short O < inf > acid < /inf > -H⋯O < inf > water < /inf > hydrogen bonds in a multicenter array

Abstract

The occurrence of short hydrogen bonds in pyrazine di-, tri-, and tetracarboxylic acid dihydrates was analyzed. A very short O- H···O hydrogen bond was characterized in one of the tetracids. The synergy from resonance and polarization assistance in the finite, neutral array was found to be sufficient to result in short O-H···H hydrogen bonds when the carboxylic acid donor is activated. This synthon-assisted hydrogen-bond shortening phenomenon was postulated from the neutron-diffraction crystal structure.