The crystal structures of the acid salts of some dibasic acids. Part III. Potassium hydrogen malonate: a neutron diffraction study

Abstract

The results of a neutron-diffraction study are reported, and compared with those from X-ray studies. The general agreement is very close; but the positions of the methylenic protons are now more precisely determined and the C–H bond length is 1·082(7)Å.

The ‘very short’ and crystallographically symmetrical hydrogen bond, for which O ⋯ H ⋯ O is 2·459(5) by X-rays and 2·468(6)Å by neutrons, and whether such symmetry is genuine are discussed. There is also a note on the classification of acid salts and related compounds according to their crystal structures and i.r. spectra.