L-Threonine at 12 K

The crystal structure of L-threonine, C₄H₉NO₃, was redetermined at 12 K. The present X-ray data allowed the determination of more accurate molecular geometry and of all the H-atom positions. The precision of the C-C, C-N and C-O distances is 0.002 Å or better, while that of the H-atom distances is 0.02 Å. The shape of the molecule relative to the C^[alpha]-C^[beta] bond corresponds to the staggered (D_3 d) conformation, with the H atoms at C^[alpha] and C^[beta] trans to each other, yielding the least-crowded molecular conformation. All H atoms of the NH₃ and OH groups are involved in intermolecular hydrogen bonds, which interconnect the molecules to form a three-dimensional network.

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