Crystal structure of oxalatobis(ethylenediamine)chromium(III) bis(oxalato)ethylenediaminechromate(III) dihydrate, [Cr(NH2·CH2·CH2·NH2)2C2O4][CrNH2·CH2·CH2·NH2(C2O4)2],2H2O

Abstract

The structure of oxalatobis(ethylenediamine)chromium(III) bis(oxalato)ethylenediaminechromate(III) dihydrate, [Cr(en)₂(ox)][Cr(en)(ox)₂],2H₂O (where en = NH₂·CH₂·CH₂·NH₂ and ox = C₂O₄), has been determined from three-dimensional X-ray data collected by a scintillation counter (R= 0·0923 for 2021 independent reflections). The salt crystallizes in space group P2/c of the monoclinic system in a cell of dimensions a= 10·61(2), b= 8·01(2), c= 14·05(2)Å, β= 112·8(1)°, with Z= 2. The structure consists of discrete [Cr(en)₂(ox)]⁺ and [Cr(en)(ox)₂]^– ions linked by intermolecular hydrogen bonding to neighbouring ions and to the water molecules. Both anion and cation possess two-fold axes which coincide with the two-fold axes of the space group. The conformation of the ethylenediamines in the cation is Λλλ but the ethylenediamine in the anion is found in both Λδ- and Λλ-conformations.