Smith Graham, Wermuth Urs D, White Jonathan M
School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia.
Acta Crystallogr C. 2007 Aug;63(Pt 8):o489-92. doi: 10.1107/S0108270107032295. Epub 2007 Jul 26.
The structure of a third pseudopolymorphic hydrate of brucine, brucine-water (1/2) [systematic name: 2,3-dimethoxystrychnidin-10-one-water (1/2)], C(23)H(26)N(2)O(4).2H(2)O, has been determined at 130 K. The asymmetric unit comprises two independent brucine molecules and four water molecules of solvation. The four water molecules form uncommon cyclic hydrogen-bonded homomolecular R(4)(4)(8) tetramer rings, which then form primary hydrogen-bonded chain substructures extending down the 2(1) screw axis in the unit cell. The two brucine molecules are linked peripherally to these substructures by either single O-H...N(brucine) or asymmetric three-centre O-H...O(brucine) hydrogen bonds.
马钱子碱的第三种假多晶型水合物，马钱子碱 - 水（1/2）[系统名称：2,3 - 二甲氧基士的宁 - 10 - 酮 - 水（1/2）]，C(23)H(26)N(2)O(4).2H(2)O 的结构已在 130 K 下测定。不对称单元包含两个独立的马钱子碱分子和四个溶剂化水分子。这四个水分子形成不常见的环状氢键同分子 R(4)(4)(8) 四聚体环，然后形成沿晶胞中的 2(1) 螺旋轴向下延伸的初级氢键链亚结构。两个马钱子碱分子通过单个 O - H...N（马钱子碱）或不对称三中心 O - H...O（马钱子碱）氢键在周边与这些亚结构相连。
