The Crystal Structure of L_s-Threonine¹

Abstract

In the three-year investigation described below, we have determined by X-ray diffraction methods the crystal structure of L-threonine. This work has confirmed the molecular structure and the relative configurations of the asymmetric centers as deduced by Rose and co-workers, and has also given detailed information concerning bond lengths, bond angles, hydrogen bonding, and van der Waals packing. Because of our high confidence in the experimental data, we have striven toward the fullest possible utilization of their precision. In this connection we have developed, improved, or used for the first time a number of new techniques: the use of the entire three-dimensional Patterson function, a more rapidly convergent non-centrosymmetric Fourier method, an analytical method for locating Fourier maxima, a “three-dimensional” least squares procedure for the simultaneous refinement of all positional parameters (except those of hydrogen atoms), punched card methods for calculating structure factors and for least squares refinement, and methods for estimating the precision of the parameter determination. Most of these will be described only briefly here, and some will be described in detail elsewhere.