Saeed Aamer, Qasim Muhammad, Simpson Jim
Department of Chemistry, Quaid-I-Azam University, Islamabad 45320, Pakistan.
Acta Crystallogr C. 2013 Jul;69(Pt 7):790-3. doi: 10.1107/S0108270113015229. Epub 2013 Jun 14.
The title compound, C10H11BrO4, a useful precursor to pharmaceutically active isocoumarin and isochroman derivatives, crystallizes with two unique molecules in the asymmetric unit. A π-π stacking interaction links the planar molecules in the asymmetric unit. Additional π-π contacts stack pairs of molecules along the c axis. A feature of the crystal packing is the presence of a number of short Br···O contacts. A particularly unusual arrangement involves the formation of dimers, with pairs of Br···O contacts imposing a close Br···Br interaction and generating five-membered rings within an eight-membered ring formed by two Br···O contacts. Only two comparable arrangements have been reported previously. The Br···O contacts combine with weak C-H···O hydrogen bonds to form corrugated sheets of molecules approximately parallel to (001). These sheets are stacked along the c axis by π-π interactions to generate a three-dimensional network.
标题化合物C₁₀H₁₁BrO₄是一种用于制备具有药学活性的异香豆素和异色满衍生物的有用前体，其不对称单元中有两个独特的分子。一个π-π堆积相互作用连接了不对称单元中的平面分子。额外的π-π接触沿着c轴堆叠分子对。晶体堆积的一个特征是存在许多短的Br···O接触。一种特别不寻常的排列涉及二聚体的形成，成对的Br···O接触产生紧密的Br···Br相互作用，并在由两个Br···O接触形成的八元环内生成五元环。此前仅报道过两种类似的排列。Br···O接触与弱的C-H···O氢键相结合，形成了大致平行于(001)的波纹状分子片。这些片层通过π-π相互作用沿着c轴堆叠，形成三维网络。
