采用 x-射线衍射技术首次实现了四环素加成物的结构研究。含四分子水的四环素—尿素复合物结晶系斜方体。空间群为p2_12_12_1,单位晶格大小:a=12.228(3),b=12.884(3),c=16.663(4)A。每单位晶格具有四个四环素—尿素分子(含4分子水)。用直接法测得了结构,对用于分析的2395反射波而言,用最小二乘法精确计算至最终非加权残量为0.043。用各种 The structure of tetracycline adduct was firstly studied by x-ray diffraction. Tetrahydric tetracycline - urea complex crystal system rhombohedron. The space group is p2_12_12_1, the unit lattice size is: a = 12.228 (3), b = 12.884 (3), c = 16.663 (4) A. There are four tetracycline-urea molecules per unit lattice (containing 4 molecules of water). The structure was measured by the direct method, and for the 2395 reflection used for the analysis, the least square method was used to calculate exactly the final unweighted residual to 0.043. With all kinds