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首页> 外文期刊>Acta Crystallographica, Section B. Structural Science >Charge density in orthorhombic NiSO4.7H(2)O at room temperature and 25 K
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Charge density in orthorhombic NiSO4.7H(2)O at room temperature and 25 K

机译：室温和25 K下正交晶NiSO4.7H（2）O中的电荷密度

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摘要

The charge-density distribution in the title compound nickel sulfate heptahydrate has been determined by multipole refinement against single crystal X-ray intensity data. For the refinement at 25 K hydrogen positions and displacement parameters were fixed to values determined from neutron data. The charge density based on the deformation functions of all atoms in the structure is compared with the individual densities calculated from the deformation functions of only nickel or the separate water molecules. In this way the effects of simple superposition of the individual densities have been studied. The individual deformation density around nickel is in good qualitative agreement with that expected for an approximately octahedral Ni(H2O)(6)(2+) complex in a weak ligand field. However, the maximum densities are not found precisely in the planes defined by nickel and the six water ligands, which illustrates that it is necessary to consider the crystal field due to the whole crystalline environment. The individual densities of the water molecules show clear polarization of the lone-pair densities according to the coordination of the water molecules: tetrahedral coordination leads to two resolved lone-pair peaks, whereas planar trigonal coordination leads to just one single peak. Crystal data: NiSO4.7H(2)O, M-r = 280.87, P2(1)2(1)2(1), Z = 4. At T = 25 K: a = 6.706 (3), b = 11.796 (6), c = 11.949 (6) Angstrom, V = 945 (1) Angstrom(3), D-x = 1.977 Mg m(-3). At 295 K: a = 6.751 (4), b = 11.746 (7), c = 12.003 (8) Angstrom, V = 952 (1) Angstrom(3), D-x = 1.959 Mg m(-3). X-ray study: F(000) = 584, lambda(Mo K alpha) = 0.71069 Angstrom, mu = 2.255 mm(-1). At 25 K: R(F) = 0.014 for 10 185 reflections. At 295 K: R(F) = 0.015 for 5723 reflections. Neutron study at 25 K: lambda = 1.215 Angstrom, mu = 0.261 mm(-1), R(F) = 0.034 for 1381 reflections.
机译：标题化合物七水合硫酸镍中的电荷密度分布已通过针对单晶X射线强度数据的多极精细化方法确定。为了在25 K时进行精炼，将氢的位置和位移参数固定为根据中子数据确定的值。将基于结构中所有原子的变形函数的电荷密度与仅根据镍或单独的水分子的变形函数计算出的单个密度进行比较。通过这种方式，已经研究了单个密度简单叠加的效果。镍周围的单个变形密度与弱配体场中大约八面体的Ni（H2O）（6）（2+）络合物的预期质量定性一致。然而，在由镍和六个水配体限定的平面中未精确找到最大密度，这说明由于整个晶体环境，必须考虑晶体场。根据水分子的配位，水分子的各个密度显示出孤对密度的明显极化：四面体配位导致两个解析的孤对峰，而平面三角配位导致仅一个单个峰。晶体数据：NiSO4.7H（2）O，Mr = 280.87，P2（1）2（1）2（1），Z = 4。在T = 25 K时：a = 6.706（3），b = 11.796（6 ），c = 11.949（6）埃，V = 945（1）埃（3），Dx = 1.977 Mg m（-3）。在295 K时：a = 6.751（4），b = 11.746（7），c = 12.003（8）埃，V = 952（1）埃（3），D-x = 1.959 Mg m（-3）。 X射线研究：F（000）= 584，λ（Mo K alpha）= 0.71069埃，mu = 2.255 mm（-1）。在25 K下：10（185）次反射的R（F）= 0.014。在295 K下：5723次反射的R（F）= 0.015。在25 K下的中子研究：对于1381次反射，λ= 1.215埃，mu = 0.261 mm（-1），R（F）= 0.034。

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