The title compounds, C11H11BrO3, (I), and C11H11NO5, (II), respectively, are derivatives of 6-hydroxy-5,7,8-trimethylchroman-2-one substituted at the 5-position by a Br atom in (I) and by a nitro group in (II). The pyranone rings in both molecules adopt half-chair conformations, and intramolecular O—H...Br [in (I)] and O—H...Onitro[in (II)] hydrogen bonds affect the dispositions of the hydroxy groups. Classical intermolecular O—H...O hydrogen bonds are found in both molecules but play quite dissimilar roles in the crystal structures. In (I), O—H...O hydrogen bonds form zigzagC(9) chains of molecules along theaaxis. Because of the tetragonal symmetry, similar chains also form alongb. In (II), however, similar contacts involving an O atom of the nitro group form inversion dimers and generateR22(12) rings. These also result in a close intermolecular O...O contact of 2.686 (4) Å. For (I), four additional C—H...O hydrogen bonds combine with π–π stacking interactions between the benzene rings to build an extensive three-dimensional network with molecules stacked along thecaxis. The packing in (II) is much simpler and centres on the inversion dimers formed through O—H...O contacts. These dimers are stacked through additional C—H...O hydrogen bonds, and further weak C—H...O interactions generate a three-dimensional network of dimer stacks.
标题化合物 C11H11BrO3(I)和 C11H11NO5(II)分别是 6-羟基-5,7,8-三甲基苯并吡喃-2-酮的衍生物,(I) 的 5 位被一个 Br 原子取代,(II) 的 5 位被一个硝基取代。这两个分子中的吡喃酮环都采用半周构象,分子内的 O-H...Br(在 (I) 中)和 O-H...Onitro(在 (II) 中)氢键影响羟基的排列。两种分子中都存在典型的分子间 O-H...O 氢键,但在晶体结构中的作用却大相径庭。在 (I)中,O-H...O 氢键沿轴向形成人字形 C(9)分子链。由于呈四方对称,沿 b 轴也会形成类似的分子链。但在(II)中,涉及硝基的一个 O 原子的类似接触会形成反转二聚体并生成 R22(12)环。这也导致分子间的 O...O 接触达到 2.686 (4) Å。对于 (I),另外四个 C-H...O氢键与苯环之间的π-π堆积相互作用相结合,构建了一个广泛的三维网络,分子沿轴向堆积。(II)中的堆积要简单得多,主要是通过 O-H...O 接触形成的反向二聚体。这些二聚体通过额外的 C-H...O 氢键堆叠,进一步的微弱 C-H...O 相互作用产生了二聚体堆叠的三维网络。