Tris{[tris(2-hydroxymethyl)methyl]ammonium} D-3-Phosphoglycerate at 150K and Tris(cyclohexylammonium) D-3-Phosphoglycerate Ethanol Solvate at 85K

The structures of the D-3-phosphoglycerate trianion in the tris{[tris(2-hydroxymethyl)methyl]ammonium} salt, 3C₄H₁₂NO₃⁺.C₃H₄O₇P³⁻, (I), and in the tris(cyclohexylammonium) ethanol solvate 3C₆H₁₄N⁺.C₃H₄O₇P³⁻.C₂H₅OH, (II), has been determined by X-ray analyses at 150 and 85 K, respectively. A notable feature of (I) is the shortest P—O(ester) bond [1.607 (2) Å] found so far for the completely ionized phosphate ester group. In contrast, in (II) this bond length is 1.627 (2) Å, similar to that observed in other doubly ionized phosphate ester groups. In (II) the carboxyl­ate group is twisted by −23.5 (4)° relative to the α-hydroxyl group, as indicated by the O1—C1—C2—O2 torsion angle, whereas in (I), the O2—C2—C1—O1 system is almost planar. Both crystal structures are stabilized by hydrogen bonds utilizing all N and O atoms.

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