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【求助】[10金幣求教]發(fā)晶體學(xué)報(bào)C時(shí),comment倒數(shù)第二段,氫的位置該怎么描述
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在學(xué)校的分析測試中心做的晶體衍射,沒有說明該怎么樣描述氫的位置。看到有文獻(xiàn)這樣寫, 但是不懂什么意思,請(qǐng)高手幫忙解釋一下。All of H atoms were found in a different Fourier synthesis. In order to maximize the data/parameter ratio, H atoms bound to C atoms were placed in geometrically idealized positions (C—H = 0.93–0.98 Å and N-H = 0.86 Å AFIX 43) and constrained to ride on their parent atoms, with Uiso (H) values of 1.2Ueq(C, N). The OH groups were refined as rigid groups allowed to rotate but not tip (AFIX 147), with O—H distances of 0.82 Å and Uiso (H) values of 1.5Ueq(O).(這段話是不是通用的?Uiso (H) values of 1.2Ueq(C, N). Uiso (H) values of 1.5Ueq(O).分別是什么意思?AFIX 43和AFIX 147又是什么意思?) 還有人這樣寫的: In the absence of suitable anomalous scattering, Friedel equivalents could not be used to determine the absolute structure. Refinement of the Flack (1983) parameter led to an inconclusive value [0.4 (6)]. Therefore, 1693 Friedel equivalents were merged before the final refinement and the known configuration of the parent molecule was used to define the enantiomer of the final model. (這段是什么意思? 為什么有的文章寫這一段,有的不寫? 這里面對(duì)應(yīng)數(shù)字在哪個(gè)文件中可以找到) All H atoms were found in a difference Fourier synthesis. The OH groups were refined as rigid groups allowed to rotate but not to tilt, with O—H = 0.82 A ° and Uiso(H) = 1.5Ueq(O). The remaining H atoms were placed in geometrically idealized positions, with C—H = 0.93–0.98 A ° and N—H = 0.86 A ° , and constrained to ride on their parent atoms, with Uiso(H) = 1.2Ueq(C,N) |
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