Buist Amanda R, Kennedy Alan R, Manzie Craig
Westchem, Department of Pure & Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, Scotland.
Vale of Leven Academy, Main Street, Alexandria G83 0BH, Scotland.
Acta Crystallogr C Struct Chem. 2014 Feb;70(Pt 2):220-4. doi: 10.1107/S2053229614000825. Epub 2014 Jan 25.
The structures of two anhydrous salt phases of theophylline, namely 1,3-dimethyl-2,6-dioxo-7H-purin-9-ium tetrafluoroborate, C7H9N4O2(+)·BF4(-), and 1,3-dimethyl-2,6-dioxo-7H-purin-9-ium chloride, C7H9N4O2(+)·Cl(-), are reported together with the structures of two monohydrate salt forms, namely 1,3-dimethyl-2,6-dioxo-7H-purin-9-ium chloride monohydrate, C7H9N4O2(+)·Cl(-)·H2O, and 1,3-dimethyl-2,6-dioxo-7H-purin-9-ium bromide monohydrate, C7H9N4O2(+)·Br(-)·H2O. The monohydrate structures are mutually isostructural, with the cations and anions lying on crystallographic mirror planes (Z' = ½). The main intermolecular interaction motif is a hydrogen-bonding network in the same mirror plane. The tetrafluoroborate structure is based on planar hydrogen-bonded theopylline cation dimers; the anions interact with the dimers in a pendant fashion. The anhydrous chloride structure has Z' = 2 and in contrast to the other species it does not form planar hydrogen-bonded constructs, instead one-dimensional chains of cations and anions propagate parallel to the crystallographic c direction. An earlier report claiming to describe an anhydrous structure of theophylline hydrochloride is re-examined in light of these results. It is concluded that the earlier structure has been reported in the wrong space group and that it has been chemically misidentified.
报道了茶碱的两种无水盐相，即1,3 - 二甲基 - 2,6 - 二氧代 - 7H - 嘌呤 - 9 - 鎓四氟硼酸盐（C7H9N4O2(+)·BF4(-)）和1,3 - 二甲基 - 2,6 - 二氧代 - 7H - 嘌呤 - 9 - 鎓氯化物（C7H9N4O2(+)·Cl(-)）的结构，以及两种一水合物盐形式，即1,3 - 二甲基 - 2,6 - 二氧代 - 7H - 嘌呤 - 9 - 鎓氯化物一水合物（C7H9N4O2(+)·Cl(-)·H2O）和1,3 - 二甲基 - 2,6 - 二氧代 - 7H - 嘌呤 - 9 - 鎓溴化物一水合物（C7H9N4O2(+)·Br(-)·H2O）的结构。一水合物结构是同构的，阳离子和阴离子位于晶体学镜面（Z' = ½）上。主要的分子间相互作用模式是在同一镜面内的氢键网络。四氟硼酸盐结构基于平面氢键连接的茶碱阳离子二聚体；阴离子以悬垂方式与二聚体相互作用。无水氯化物结构的Z' = 2，与其他物种不同，它不形成平面氢键连接的结构，而是阳离子和阴离子的一维链沿晶体学c方向平行延伸。根据这些结果重新审视了一份早期声称描述了茶碱盐酸盐无水结构的报告。得出的结论是，早期报道的结构空间群错误且化学鉴定有误。
