Ahn Shinbyoung, Guo Fang, Kariuki Benson M, Harris Kenneth D M
School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, England.
J Am Chem Soc. 2006 Jul 5;128(26):8441-52. doi: 10.1021/ja0573155.
To date, only one crystal structure has been reported in the literature for oxalyl dihydrazide [H(2)N.NH.CO.CO.NH.NH(2)]. In the present paper, we report the discovery of four new polymorphs of oxalyl dihydrazide, obtained by crystallization from solution under different conditions, including the use of different crystallization solvents. All polymorphs have the trans-trans-trans conformation of the N-N-C-C-N-N backbone, but the positions of the hydrogen atoms of the NH(2) groups relative to this backbone differ between the different polymorphs through variation of the torsion angle around each NH-NH(2) bond. The different polymorphs display a range of different hydrogen-bonding arrangements, constructed from different types of hydrogen-bonded array. The existence of several different potential hydrogen-bond donor and hydrogen-bond acceptor groups in the oxalyl dihydrazide molecule, together with the fact that the N-H bonds of the NH(2) groups adopt different orientations with respect to the molecular plane, leads to several possible geometric permutations for hydrogen-bonding arrangements in the solid state. It would not be surprising if even more polymorphs of oxalyl dihydrazide are discovered in the future.
迄今为止，文献中仅报道了草酰二肼[H(2)N.NH.CO.CO.NH.NH(2)]的一种晶体结构。在本文中，我们报告了通过在不同条件下从溶液中结晶获得的草酰二肼的四种新多晶型物，包括使用不同的结晶溶剂。所有多晶型物的N-N-C-C-N-N主链均具有反-反-反构象，但不同多晶型物中NH(2)基团的氢原子相对于该主链的位置因围绕每个NH-NH(2)键的扭转角变化而不同。不同的多晶型物表现出一系列不同的氢键排列方式，这些排列方式由不同类型的氢键阵列构成。草酰二肼分子中存在几种不同的潜在氢键供体和氢键受体基团，再加上NH(2)基团的N-H键相对于分子平面采用不同的取向，导致固态中氢键排列存在几种可能的几何排列方式。如果未来发现更多草酰二肼的多晶型物，也不足为奇。
