Sridhar Balasubramanian, Ravikumar Krishnan, Varghese Babu
Laboratory of X-ray Crystallography, Indian Institute of Chemical Technology, Hyderabad 500 007, India.
Acta Crystallogr C. 2009 May;65(Pt 5):o202-6. doi: 10.1107/S0108270109011780. Epub 2009 Apr 10.
In 9H-adenine-1,7-diium hemioxalate chloride, C(5)H(7)N(5)(2+).0.5C(2)O(4)(2-).Cl(-), (I), adenine is doubly protonated, while in 7H-adenin-1-ium semioxalate hemi(oxalic acid) monohydrate, C(5)H(6)N(5)(+).C(2)HO(4)(-).0.5C(2)H(2)O(4).H(2)O, (II), adenine and one oxalate anion are both monoprotonated. In (I), the adeninium cation forms R(2)(2)(8) and R(1)(2)(5) hydrogen-bonding motifs with the centrosymmetric oxalate anion, while in (II), the cation forms R(2)(1)(6) and R(1)(2)(5) motifs with the centrosymmetric oxalic acid molecule and R(1)(2)(5)and R(2)(2)(9) motifs with the monoprotonated oxalate anion. Linear hydrogen-bonded trimers are observed in (I) and (II). In both structures, the hydrogen bonds lead to the formation of two-dimensional supramolecular hydrogen-bonded sheets in the crystal packing. The significance of this study lies in the analysis of the interactions occurring via hydrogen bonds and the diversity seen in the supramolecular hydrogen-bonded networks as a result of such interactions.
在9H-腺嘌呤-1,7-二鎓半草酸氯化物C(5)H(7)N(5)(2+).0.5C(2)O(4)(2-).Cl(-)（I）中，腺嘌呤被双重质子化，而在7H-腺嘌呤-1-鎓半草酸盐半（草酸）一水合物C(5)H(6)N(5)(+).C(2)HO(4)(-).0.5C(2)H(2)O(4).H(2)O（II）中，腺嘌呤和一个草酸根阴离子均被单质子化。在（I）中，腺嘌呤阳离子与中心对称的草酸根阴离子形成R(2)(2)(8)和R(1)(2)(5)氢键基序，而在（II）中，阳离子与中心对称的草酸分子形成R(2)(1)(6)和R(1)(2)(5)基序，并与单质子化的草酸根阴离子形成R(1)(2)(5)和R(2)(2)(9)基序。在（I）和（II）中均观察到线性氢键三聚体。在这两种结构中，氢键导致在晶体堆积中形成二维超分子氢键片层。本研究的意义在于分析通过氢键发生的相互作用以及由于此类相互作用在超分子氢键网络中看到的多样性。
