MULTINUCLEAR MAGNETIC-RESONANCE STUDIES OF THE HYDROLYSIS OF ALUMINUM(III) .8. BASE HYDROLYSIS MONITORED AT VERY HIGH MAGNETIC-FIELD
MULTINUCLEAR MAGNETIC-RESONANCE STUDIES OF THE HYDROLYSIS OF ALUMINUM(III) .8. BASE HYDROLYSIS MONITORED AT VERY HIGH MAGNETIC-FIELD
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DOI：
10.1039/dt9880001347
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发表时间：
1988-05-01
期刊：
影响因子：
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通讯作者：
ELDERS, JM
中科院分区：
文献类型：
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作者：
AKITT, JW;ELDERS, JM
用高场~ 1H和~（27）Al核磁共振谱对碱解铝溶液进行了新的研究。谱现代仪器灵敏度的提高使得在低至1 × 10-3 mol dm-3的浓度下获得数据，其中一些是定量的，并且1H n.m.r.转移到非水溶剂的溶质的光谱提供了新的结构数据。结果表明，十三聚体阳离子[AlO 4Al 12（OH）24（H2O）12]7+是在较低浓度下形成的主要物种，并且几乎是在20 × 10-3 mol dm-3以下形成的唯一物种。在高于此的浓度下，并且在中等水解水平下，形成具有接近{[Al（OH）2.5]1/2+}n的化学计量的低聚混合物，并且其可以由诸如[Al 2（OH）5]+、[Al 3（OH）8]+、[Al 4（OH）10]2+和[Al 5（OH）13]2+的物质组成。部分氘化产生结合水的质子共振的同位素分裂，其允许这些与OH桥质子的共振区分开。还获得了由于氢-氘取代AlO 6片段而导致的精细结构的指示，其有利于更稠合的结构，并且这与低聚物在简单稀释时转化为十三聚体的容易性雅阁。现在可以肯定的是，在固态中发现的二羟基桥接二聚体不是这些溶液的重要组成部分。氧气-17 n.m.r.还简要报告了数据。
New studies of base-hydrolysed aluminium(III) solutions were made using high-field 1H and 27Al n.m.r. spectroscopy. The increased sensitivity of the modern equipment has allowed data to be obtained at concentrations as low as 1 × 10–3 mol dm–3, some of it quantitative, and the 1H n.m.r. spectra of solutes transferred to non-aqueous solvents has provided new structural data. The results enable it to be stated quite unequivocally that the tridecameric cation [AlO4Al12(OH)24(H2O)12]7+ is the principal species formed at lower concentrations, and is virtually the only one formed below 20 × 10–3 mol dm–3. At concentrations higher than this, and at intermediate levels of hydrolysis, an oligomeric mixture is formed with a stoicheiometry close to {[Al(OH)2.5]1/2+}n and which could be composed of species such as [Al2(OH)5]+, [Al3(OH)8]+, [Al4(OH)10]2+, and [Al5(OH)13]2+. Partial deuteriation produces isotopic splitting of the proton resonances of bound water which allows these to be distinguished from the resonances of OH-bridge protons. An indication of fine structure due to hydrogen–deuterium substitution on AlO6 fragments is also obtained which favours the more condensed structures and this is in accord with the ease with which the oligomer is converted into the tridecamer on simple dilution. It is now certain that the dihydroxo-bridged dimer found in the solid state is not a significant constituent of these solutions. Oxygen-17 n.m.r. data are also briefly reported.