Yang H W, Craven B M
Department of Crystallography, University of Pittsburgh, PA 15260, USA.
Acta Crystallogr B. 1998 Dec 1;54 ( Pt 6):912-20. doi: 10.1107/s0108768198006545.
The crystal structure of 2-pyridone has been redetermined from high-resolution X-ray data collected at 123 K. The molecule is in the lactam form. Bond lengths (corrected for rigid-body libration) and angles have been determined with s.u.'s of 0.001 A and 0.1 degree, respectively. The hydrogen-bonded cyclic dimers which occur in the vapor and in solution are absent in the crystal where molecules are linked by N-H...O hydrogen bonds to form puckered chains. There also appears to be a weaker C-H...O interaction (H...O, 2.57 A) and weak C-H...pi or van der Waals interactions occurring on both sides of the pyridone ring. Following a refinement of the structure assuming Stewart's rigid pseudo-atom model, the electronic charge density distribution in the crystal and its Laplacian have been calculated for atoms at rest. The total electrostatic potential has been mapped for an isolated molecule and the molecular dipole moment has been determined [8.8 (19) D; 1D approximately = 3.33564 x 10(-30) C m]. Critical points in the electron density have been located for the bonds within the molecule and for the molecular interactions cited above. For the C-H...pi interactions, only the spherical components of the valence density for the pyridone ring atoms contribute effectively at the critical points. Hence, these may be better described as van der Waals interactions.
已根据在123 K下收集的高分辨率X射线数据重新测定了2-吡啶酮的晶体结构。该分子呈内酰胺形式。键长（经刚体振动校正）和键角的测定标准偏差分别为0.001 Å和0.1°。在晶体中不存在在气相和溶液中出现的氢键连接的环状二聚体，分子通过N-H...O氢键连接形成褶皱链。吡啶酮环两侧似乎还存在较弱的C-H...O相互作用（H...O，2.57 Å）以及较弱的C-H...π或范德华相互作用。在采用斯图尔特刚性伪原子模型对结构进行精修后，计算了晶体中静止原子的电子电荷密度分布及其拉普拉斯算子。绘制了孤立分子的总静电势图并确定了分子偶极矩[8.8 (19) D；1 D约 = 3.33564×10⁻³⁰ C m]。已确定了分子内化学键以及上述分子间相互作用的电子密度临界点。对于C-H...π相互作用，在临界点处仅吡啶酮环原子价密度的球形分量有有效贡献。因此，这些相互作用可能更宜描述为范德华相互作用。
