The crystal structure of the molecular cocrystal L-malic acid L-tartaric acid (1/1)

The synthesis and X-ray single crystal structure determination of the molecular cocrystal L-malic acid L-tartaric acid (1/1) 1, the first example of a dimeric cocrystal incorporating two aliphatic carboxylic acids, are reported. [C4H6O5][C4H6O6], triclinic, P1, a = 4.835(1), b = 6.488(1), c = 9.227(1) Angstrom, alpha = 73.83(1), beta = 88.32(1), gamma = 77.32 degrees, V = 271.06(8) Angstrom(3), Z = 1, D-calc = 1.741 Mg m(-3), T = 123(2) K, mu(Mo-K-alpha) = 0.169 mm(-1). A total of 1238 reflections were measured and 1181 unique reflections were used in the refinement. The final parameters for observed data were R = 0.030, R(w)(2) = 0.085 and R = 0.033, R(w)(2) = 0.134 for all data. The competition between complimentary hydrogen-bond sites of the two acids, which results in the unexpected heteromeric complex, is discussed, and the observed packing arrangements, and the structural consequences arising from the presence of the extended hydrogen-bond networks, are examined in detail.