The nature of the H3O+ hydronium ion in benzene and chlorinated hydrocarbon solvents.: Conditions of existence and reinterpretation of infrared data
The nature of the H3O+ hydronium ion in benzene and chlorinated hydrocarbon solvents.: Conditions of existence and reinterpretation of infrared data
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DOI：
10.1021/ja0551335
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发表时间：
2006-02-15
影响因子：
15
通讯作者：
Reed, CA
中科院分区：
文献类型：
--
作者：
Stoyanov, ES;Kim, KC;Reed, CA
在弱碱性溶剂苯、二氯甲烷和1，2-二氯乙烷中得到了C-3v对称离子H3O+的盐。这是通过使用CHB11R5X6-(R=H，Me，Cl；X=Cl，Br1)型碳硼烷反离子来实现的，因为它们结合了合适的反离子所需的三个性质：非常低的碱度，低的极化率和高的化学稳定性。H3O+离子的存在需要与溶剂或阴离子碱形成三个或多或少相等的、中等到强的氢键。用最少的碱性阴离子如CHB11Cl11-，红外光谱表明[H(3)O(+.)3Solv]式的C3v对称三元化合物是与氯碳溶剂和苯形成的，后者形成了pi键。当溶剂和阴离子具有相当的碱度时，形成[H(3)O(+.)NSolv(.)Carborane]型接触离子对并保持接近C3v对称性。H3O+离子存在的条件比以前所认为的要严格得多。在下端以二氯甲烷和上端以磷酸三丁酯为界的溶剂碱度范围外，与不满足弱碱性、低极化率和高化学稳定性的严格要求的阴离子形成较低的对称性物种。从H3O+到周围碱的一个氢键变得比另外两个更强。对于比二氯甲烷弱的碱，C3v对称性的扭曲很小。对于比磷酸三丁酯更强的碱，形成的H2O-H+-B型物种与H5O2+离子的关系比与H3O+离子的关系更密切。IR数据允许定义对称H3O+离子存在的标准。这包括v(Max)(OH)和增量(OH3)的频率之间的线性关系，其中v(Max)(OH)的频率在3010-2536 cm(-1)的范围内，增量(OH3)的频率在1597-1710 cm(-1)的范围内。这提供了一种简单的方法来评估一水合酸中质子状态公式的正确性。特别是，被认为来自H3O+SbCl6-的红外光谱的30年引用经典被重新解释为(H2O)(X)(HSbCl6)-H-。水合物。证实了结晶H(3)O(+)A(-)盐(A(-)=Cl-，NO3-)中氢离子公式的正确性，但当A-为含氟阴离子时，C3v对称性发生了扭曲。
Salts of the C-3v symmetric hydronium ion, H3O+, have been obtained in the weakly basic solvents benzene, dichloromethane, and 1,2-dichloroethane. This is made possible by using carborane counterions of the type CHB11R5X6 - (R = H, Me, Cl; X = Cl, Br, 1) because they combine the three required properties of a suitable counterion: very low basicity, low polarizability, and high chemical stability. The existence of the H3O+ ion requires the formation of three more-or-less equivalent, medium-to-strong H-bonds with solvent or anion bases. With the least basic anions such as CHB11Cl11-, IR spectroscopy indicates that C3v symmetric trisolvates of formulation [H(3)O(+.)3Solv] are formed with chlorocarbon solvents and benzene, the latter with the formation of pi bonds. When the solvents and anions have comparable basicity, contact ion pairs of the type [H(3)O(+ .)nSolv(.)Carborane] are formed and close to C3v symmetry is retained. The conditions for the existence of the H3O+ ion are much more exacting than previously appreciated. Outside of the range of solvent basicity bounded at the lower end by dichloromethane and the upper end by tributyl phosphate, and with anions that do not meet the stringent requirements of weak basicity, low polarizability of high chemical stability, lower symmetry species are formed. One H-bond from H3O+ to the surrounding bases becomes stronger than the other two. The distortion from C3v symmetry is minor for bases weaker than dichloromethane. For bases stronger than tributyl phosphate, H2O-H+-B type species are formed that are more closely related to the H5O2+ ion than to H3O+. I R data allow criteria to be defined for the existence of the symmetric H3O+ ion. This includes a linear dependence between the frequencies of v(max) (OH) and delta(OH3) within the ranges 3010-2536 cm(-1) for v(max)(OH) and 1597-1710 cm(-1) for delta(OH3). This provides a simple way to assess the correctness of the formulation of the proton state in monohydrated acids. In particular, the 30-year-old citation classic of the IR spectrum believed to arise from H3O+ SbCl6- is reinterpreted in terms of (H2O)(x)(HSbCl6)-H-. hydrates. The correctness of the hydronium ion formulation in crystalline H(3)O(+)A(-) salts (A(-) = Cl-, NO3-) is confirmed, although, when A- is a fluoroanion, distortions from C3v symmetry are suggested.