<i>N</i> , <i>N</i> ′-Bis[tris(hydroxymethyl)methyl]propane-1,3-diamine (bis-tris propane)

The title compound, C₁₁H₂₆N₂O₆, used for the preparation of buffer solutions and high-nuclearity coordination complexes, crystallizes with a half mol-ecule in the asymmetric unit. The full mol-ecule is completed through mirror symmetry <i>m</i> in the space group <i>Pnma</i>. The mol-ecular shape is bent and, as a consequence, some H atoms are disordered to avoid too short H⋯H intra-molecular contacts. Mol-ecules in the crystal are linked <i>via</i> O-H⋯N and N-H⋯O hydrogen bonds, forming chains along [100], which are further packed through other O-H⋯O hydrogen bonds between hy-droxy groups. The here-reported structure probably represents the less-stable form in a set of polymorphs.