Über basische Aluminiumsalze und ihre Lösungen. X. NMR-Untersuchungen am tridekameren Al-oxo-hydroxo-Kation

Basic Aluminum Salts and their Solutions. X. NMR-Investigations on the Tridecameric Al-Oxo-Hydroxo Cation Using solid-state high resolution ²⁷Al-NMR it is shown that in the basic aluminum chloride with a degree of alkalinity r = OH/Al = 2.5 cations of the Al₁₃O₄(OH)₂₅(H₂O)₁₁]⁶⁺ type exist. The ¹H-NMR detects besides the constitutional water still an amount of mobile, enclosed H₂O molecules which can be removed by thermal treatment at 104°C. The ²⁷Al spectrum of the aqueous solutions of the chloride shows only one peak at 62.5 ppm which is characteristic for the tridecameric cation. Adding HCl to the solution causes a decomposition to low-molecular species (peak at 0 ppm). Adding NaOH to the aqueous solution of the chloride effects a rearrangement of the tridecameric cations to higher molecular particles which are no more accessible by ²⁷Al-NMR.