柯卡因甲基溴化物相角双解判别计算

Computational Study on the Solution of Phase-ambiguity of the Crystal C₁₈H₂₄NO₄Br

摘要: 用药物小分子柯卡因甲基溴化物晶体学数据计算了含有反常散射的归-化结构因子模和相角(|E_H|,|E_H^-|和φ_H、φ_H^-)。又用Harker作图法,在已知|E_H|,|E_H^-|和重原个Br的原子坐标的条件下,求得φ_H、φ_H^-的两种可能双解。采用双相角结构不变量的概率估计算式(ω=φ_H+φ_H^-=-ξ),判别出相角双解的正确值。结果表明,这个计算与柯卡因甲基碘化物的计算同样能说明Hauptman概率估计算式是有用的。

Abstract: The normalized structure factor module and phase withanomalous scattering(|E_H|,|E_H^-,φ_H、φ_H^-) are calculated with the crystallographic data of a medical small molecule crystal C₁₈H₂₄NO₄Br. Then the two-possible ambiguity of the phase,Φ_H or Φ_H^-,is obtained by Harker construction, if the|E_H|,E_H^-| and the coordinates of the anomalous scatterer Br are known. The probabilistic estimate of two-phase structure invariants, W=Φ_H + Φ_H^-=-ξ, is used to identify the correct solution of the phase in two-possible ambiguity. The computational results show that the probabilistic estimate Hauptman's formula for C₁₈H₂₄NO₄Br is as useful as that for another crystal C₁₈H₂₄NO₄ I.