Transfer activity coefficients between water and methanol of complexes of some univalent and barium ions with dibenzocryptand 2.2.2, cryptand 2.2.2, and 18-crown-6.
Transfer activity coefficients between water and methanol of complexes of some univalent and barium ions with dibenzocryptand 2.2.2, cryptand 2.2.2, and 18-crown-6.
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DOI：
10.1073/pnas.78.12.7245
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发表时间：
1981-12
影响因子：
11.1
通讯作者：
M. K. Chantooni;I. Kolthoff
中科院分区：
文献类型：
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作者：
M. K. Chantooni;I. Kolthoff
钠、钾、银、铊 (I) 和钡与二苯并穴状化合物 2.2.2 的络合物的稳定性常数 K(f)LM(n+)（其中 L = 配体，M(n+) = 金属离子）在 25°C 的水和甲醇中测定。还测定了两种配体二苯并隐配体 2.2.2 和 18-crown-6 之间的甲醇和水之间的转移活性系数。根据这些数据，计算了这两种配体与上述阳离子的复合物的转移活性系数。对于这些配体的单价离子络合物，此外，对于二苯并-18-冠-6和穴状配体2.2.2的这种络合物，转移活性系数的对数比配体的对数大2.5个单位。尽管甲醇和水一样是良好的氢键供体，但得出的结论是，与水中的多个水合层相比，在甲醇中仅第一溶剂化层围绕未络合配体的醚氧构建。当这些配体络合时，由于离子M(n+)-O键合，与这些醚氧的氢键大大减少。发现钡配合物的转移活性系数与配体的转移活性系数相同。这归因于 LBa(2+) 的广泛溶剂化。
Stability constants, K(f)LM(n+) (in which L = ligand and M(n+) = metal ion), of complexes of sodium, potassium, silver, thallium(I), and barium with dibenzocryptand 2.2.2 were determined at 25 degrees C in water and methanol. Also determined were transfer activity coefficients between methanol and water of two ligands, dibenzocryptand 2.2.2 and 18-crown-6. From these data, transfer activity coefficients of complexes of these two ligands with the above cations have been calculated. For univalent ion complexes of these ligands and, in addition, for such complexes of dibenzo-18-crown-6 and cryptand 2.2.2, the logarithms of the transfer activity coefficients are of the order of 2.5 units more positive than those of the ligands. Even though methanol is a good hydrogen bond donor, as is water, it is concluded that in methanol only the first solvation layer is built around an ether oxygen of the uncomplexed ligand as compared with several hydration layers in water. Hydrogen bonding to these ether oxygens when these ligands are complexed is greatly decreased as a result of ionic M(n+)-O bonding. Transfer activity coefficients of the barium complexes are found to be the same as those of the ligands. This is attributed to extensive solvation of LBa(2+).