On racemic and L-malates: a comparison of their crystal structures

Abstract

The crystal structures of eight different L-malates have been determined and refined from single-crystal X-ray diffraction data. The compounds are the monoclinic (space group P2₁, Z = 2) L-malates Ca(C₄H₄O₅)·3H₂O (a = 6.652(1) Å, b = 8.378(1) Å, c = 8.268(1) Å, β = 112.65(2)°, R = 0.027), Ni(C₄H₄O₅)·3H₂O (a = 5.762(1) Å, b = 9.006(2) Å, c = 8.406(1) Å, β = 105.54(1)°, R = 0.024), CuH₂(C₄H₄O₅)₂ (a = 9.911(1) Å, b = 5.271(1) Å, c = 11.510(1) Å, β = 109.33(1)°, R = 0.031), CsH(C₄H₄O₅)·H₂O (a = 7.439(1) Å, b = 7.481(1) Å, c = 7.852(1) Å, β = 116.67(1)°, R = 0.027) as well as the four isomorphic tetragonal (space group P4₁2₁2, Z = 4) L-malates MgH₂(C₄H₄O₅)₂·4H₂O (a = 7.524(1) Å, c = 27.459(2) Å, R = 0.041), MnH₂(C₄H₄O₅)₂·4H₂O (a = 7.548(1) Å, c = 27.707(2) Å, R = 0.027), CoH₂(C₄H₄O₅)₂·4H₂O (a = 7.519(1) Å, c = 27.537(2) Å, R = 0.030) and ZnH₂(C₄H₄O₅)₂·4H₂O (a = 7.533(1) Å, c = 27.360(2) Å, R = 0.029). A comparison of the atomic arrangements of L-malates with their racemic counterparts shows different aspects of symmetry as well as differences in the connectivity of the building units.

In addition, for all the compounds, powder diffraction data were collected, analysed and submitted to the powder diffraction file (PDF).