A second monoclinic polymorph of ethyl-enediammonium bis-(hydrogen squarate) monohydrate.

The title compound, C(2)H(10)N(2) (2+)·2HC(4)O(4) (-)·H(2)O, a new polymorph of ethyl-enediammonium bis-(hydrogen squarate) monohydrate, was synthesized by slow evaporation of an acid solution. The asymetric unit contains two hydrogen squarate anions, two half-mol-ecules of protonated ethyl-enediamine arranged around a twofold axis and one water mol-ecule. In the crystal, N-H⋯O and O-H⋯O hydrogen bonds between the hydrogen squarate anions, protonated N atoms from the amine group and water mol-ecules lead to a three-dimensional framework.

Yttrium ethyl-enediammonium squarate tetra-hydrate.

The title compound, {(C(2)H(10)N(2))(1.5)[Y(C(4)O(4))(3)(H(2)O)(4)]}(n) {system-atic name: catena-poly[sesqui(ethyl-enediammonium) [[tetra-aquabis-(squarato-κO)yttrium(III)]-μ-squarato-κ(2)O:O']]}, was synthesized by slow evaporation of an acid solution. The asymetric unit contains one yttrium cation in an anti-prismatic environnement, three squarate groups, one and a half protonated ethyl-enediamine mol-ecules and four water mol-ecules.