For [C(O)NH](N)₂P(O)-based structures, the magnitude of the differences in the N—H…O, H…O=P and H…O=C angles has been evaluated when the N—H bond lengths, determined by X-ray diffraction, were compared to the neutron normalized values and the maximum percentage difference was obtained, i.e. about 3% for the angle even if the N—H bond lengths have a difference of about 30% (0.7 Å for the X-ray and 1.03 Å for the neutron-normalized value). The symmetries of the crystals are discussed with respect to the symmetry of the molecules, as well as to the symmetry of hydrogen-bonded motifs, and the role of the most directional hydrogen bond in raising the probability of obtaining centrosymmetric crystal structures is investigated. The work was performed by considering nine new X-ray crystal structures and 204 analogous structures retrieved from the Cambridge Structural Database.

中文翻译：

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[C(O)NH](N)2P(O)基结构中的氢键方向性和对称性：X射线晶体学数据与中子归一化值之间的比较，以及可靠性评估

对于基于 [C(O)NH](N) ₂ P(O) 的结构，已评估 N-H…O、H…O=P 和 H…O=C 角度差异的大小，当通过 X 射线衍射确定的 N-H 键长与中子归一化值进行比较，并获得最大百分比差异，即即使 N-H 键长有大约 30% 的差异（X 射线为 0.7 Å，中子归一化值为 1.03 Å），角度也大约为 3%。就分子的对称性以及氢键基序的对称性讨论了晶体的对称性，并研究了最具方向性的氢键在提高获得中心对称晶体结构的可能性方面的作用。这项工作是通过考虑从剑桥结构数据库检索到的 9 种新 X 射线晶体结构和 204 种类似结构来进行的。