A new compound in kidney stones? Powder X-ray diffraction study of calcium glycinate trihydrate

The present identification of a new compound in kidney stones is relevant in clinical practice. Here, poly[[di-[mu]-aqua-bis(glycinato-[kappa]²N,O)calcium(II)] monohydrate], {[Ca(C₂H₄NO₂)₂(H₂O)₂]·H₂O}_n, has been identified in a possible kidney concretion, although it could be a `false calculus' associated with Munchausen syndrome. The crystal packing is characterized by an infinite zigzag chain of Ca atoms in [Ca(OW)₄O₂N₂] (OW is a water O atom) square anti­prisms, sharing edges formed by water mol­ecules. An uncoordinated water mol­ecule inter­connects the parallel chains in a three-dimensional hydrogen-bonding scheme. Similarities between the trihydrate and the monohydrate are described.