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首页> 外文期刊>The Journal of Chemical Physics >Hydrogen motional disorder in crystalline iron group chloride dihydrates
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Hydrogen motional disorder in crystalline iron group chloride dihydrates

机译：结晶铁氯化物二水合物中的氢情绪障碍

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The principal components and the relative orientation of the H-2 paramagnetic shift and quadrupolar coupling tensors have been measured for the MCl2 center dot 2D(2)O family of compounds, M = Mn, Fe, Co, Ni, and Cu, using the two-dimensional shifting-d echo nuclear magnetic resonance experiment in order to determine (1) the degree of unpaired electron delocalization and (2) the number and location of crystallographically distinct hydrogen sites around oxygen and their fractional occupancies. Expressions for the molecular susceptibility of 3d ion systems, where the spin-orbit coupling is a weak perturbation onto the crystal field, are derived using the generalized Van Vleck equation and used to predict molecular susceptibilities. These predicted molecular susceptibilities are combined with various point dipole source configurations modeling unpaired electron delocalization to predict H-2 paramagnetic shift tensors at potential deuterium sites. The instantaneous deuterium quadrupolar coupling and shift tensors are then combined with parameterized motional models, developed for trigonally (M = Mn, Fe, Co, and Cu) and pyramidally (M = Ni) coordinated D2O ligands, to obtain the best fit of the experimental 2D spectra. Dipole sources placed onto metal nuclei with a small degree of delocalization onto the chlorine ligands yield good agreement with the experiment for M = Mn, Fe, Co, and Ni, while good agreement for CuCl2 center dot 2D(2)O is obtained with additional delocalization onto the oxygen. Our analysis of the salts with trigonally coordinated water ligands (M = Mn, Fe, Co, and Cu) confirms the presence of bisector flipping and the conclusions from neutron scattering measurements that hydrogen bonding to chlorine on two adjacent chains leads to the water molecule in the [M(D2O)(2)Cl-4] cluster being nearly coplanar with O-M-Cl involving the shortest metal-chlorine bonds of the cluster. In the case of NiCl2 center dot 2D(2)O, the experimental parameters were found to
机译：H-2的主成分和H-2顺磁偏移和四腹耦合张力的相对取向已经测量了MCL2中心点2D（2）O类化合物，M = Mn，Fe，Co，Ni和Cu，使用该方法二维换档-D回波核磁共振实验，以确定（1）未配对的电子临床化程度和（2）氧气周围的晶体不同氢气部位的数量和位置及其分数占用。用于3D离子系统的分子敏感性的表达，其中旋转轨道耦合是在晶体场上的弱扰动，使用广义文VLECK方程导出并用于预测分子敏感性。这些预测的分子敏感性与各种点偶极源配置相结合，该偶极源配置建模未配对电子临床化，以预测潜在的氘位点的H-2顺磁移位张量。然后将瞬时的氘辅助耦合和移位张力与参数化的运动模型结合，用于三群（M = Mn，Fe，Co和Cu）和嘧术（M = Ni）配位D2O配体的参数化的运动模型，以获得最适合实验的拟合2D光谱。将偶极子核源放在金属核上，少量的渐少化上氯配体，与M = Mn，Fe，Co和Ni的实验产生良好的一致性，而CuCl2中心点2D（2）o的良好一致性是额外的将去透镜化到氧气上。我们对具有三元化的水配体（M = Mn，Fe，Co和Cu）的盐的分析证实了分子翻转的存在和中子散射测量的结论，即氢键与两个相邻链上的氯导致水分子[M（D2O）（2）CL-4]簇几乎与涉及簇的最短金属氯键的OM-Cl。在NiCl2中心点2D（2）O的情况下，发现实验参数

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