Individual Solvation Numbers around the Nickel(II) Ion in an N,N-Dimethylformamide and N,N-Dimethylacetamide Mixture Determined by Raman Spectrophotometry
Individual Solvation Numbers around the Nickel(II) Ion in an N,N-Dimethylformamide and N,N-Dimethylacetamide Mixture Determined by Raman Spectrophotometry
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通过拉曼分光光度法测定 N,N-二甲基甲酰胺和 N,N-二甲基乙酰胺混合物中镍 (II) 离子周围的单独溶剂化数
DOI：
10.2116/analsci.17.323
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发表时间：
2001
影响因子：
1.6
通讯作者：
S. Ishiguro
中科院分区：
文献类型：
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作者：
Y. Umebayashi;K. Matsumoto;Manabu Watanabe;Kazusuke Katoh;S. Ishiguro
用滴定拉曼光谱法测定了298 K时N，N -二甲基甲酰胺（DMF）和N，N -二甲基乙酰胺（DMA）混合溶液中镍离子周围的溶剂化数.本文采用DMF的面内弯曲振动（δ（O=C-N））和DMA的伸缩振动（ν（N-CH_3））。当溶剂分子与金属离子配位时，溶剂分子的这些拉曼谱带向更高的频率移动。通过分析随着金属离子浓度增加的自由和结合溶剂分子的带强度，可以评估金属离子周围的溶剂化数。由于混合物中镍（II）离子周围的DMF和DMA的单独溶剂化数是独立测定的，因此总溶剂化数是以其总和的形式获得的。发现DMA摩尔分数x = 0-1的所有混合物的总溶剂化数均为6。虽然DMF和DMA实际上具有相同的电子对供体容量，但镍（II）离子优选DMF而不是DMA，并且在x = 0.75时获得相等的溶剂化数。这归因于DMA的溶剂化空间效应。
Individual solvation numbers around the nickel(II) ion have been determined by titration Raman spectroscopy in N , N -dimethylformamide (DMF) and N , N -dimethylacetamide (DMA) mixtures at 298 K. The in-plane bending vibration ( δ (O=C–N)) of DMF and the stretching vibration ( ν (N–CH_3)) of DMA were used in the present analysis. These Raman bands of solvent molecules shift to higher frequencies upon coordination of the solvent molecules to the metal ion. By analyzing the band intensities of free and bound solvent molecules with increasing concentration of the metal ion, the solvation number around the metal ion can be evaluated. Because the individual solvation numbers of DMF and DMA around the nickel(II) ion in the mixture are determined independently, the total solvation number is obtained as their sum. It was found that the total solvation number remains 6 in all mixtures of the DMA mole fraction x = 0–1. Although DMF and DMA have practically the same electron-pair donor capacities, the nickel(II) ion prefers DMF to DMA, and an equal solvation number is attained at x = 0.75. This is ascribed to the solvation steric effect of DMA.
Kazuhiko Ozutsumi：“N,N-二甲基甲酰胺和 N,N-二甲基乙酰胺中二价过渡金属离子的溶剂化结构”
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