Bhat T N, Ammon H L
Laboratory of Molecular Biology, National Institutes of Health, Bethesda, Maryland 20892.
Acta Crystallogr C. 1990 Jan 15;46 ( Pt 1):112-6. doi: 10.1107/s0108270189005044.
C10H8F4N10O18, Mr = 632.22, monoclinic, Pc, a = 7.8885 (6), b = 6.7787 (4), c = 21.595 (2) A, beta = 108.21 (1) degree, V = 1096 (1) A3, Z = 2, Dx = 1.914 g cm-3, lambda(Cu K alpha) = 1.5418 A, mu = 18.7 cm-1, F(000) = 636, T = 293 K, 1791 unique data, 1733 with I greater than 3 sigma (I), R = 0.047. The structure was solved by the consistent electron density approach (CEDA), in which a small starting set of random phases was refined and expanded by the application of restraints to the electron density. A refinable preliminary structure was obtained by fitting a model to a 3 A map, calculated with 27 reflections (all data with d greater than 3 A, and magnitude of Fo greater than 170) whose phases had been determined by the CEDA. The molecule has an extended, open conformation; the two pairs of fluorodinitroethyl substituents located across the molecular center from each other show i and C2 pseudo-symmetry respectively.
C₁₀H₈F₄N₁₀O₁₈，Mr = 632.22，单斜晶系，Pc 空间群，a = 7.8885(6) Å，b = 6.7787(4) Å，c = 21.595(2) Å，β = 108.21(1)°，V = 1096(1) ų，Z = 2，Dx = 1.914 g/cm³，λ(Cu Kα) = 1.5418 Å，μ = 18.7 cm⁻¹，F(000) = 636，T = 293 K，1791个独立数据，1733个I > 3σ(I)的数据，R = 0.047。该结构通过一致电子密度法（CEDA）解析，即通过对一小套随机相位进行精炼，并对电子密度施加约束来扩展。通过将一个模型拟合到一个3 Å的电子密度图上得到一个可精炼的初步结构，该电子密度图是用27个反射数据（所有d > 3 Å且|Fo| > 170的数据）计算得到的，其相位已由CEDA确定。该分子具有伸展的开放构象；位于分子中心彼此相对的两对氟二硝基乙基取代基分别呈现i和C₂ 伪对称性。
