Comparative x-ray and 27Al NMR spectroscopic studies of the speciation of aluminum in aqueous systems: Al(III) complexes of N(CH2CO2H)2 (CH2CH2OH)

It is recognized that many aspects of the aq. chem. of AlIII and FeIII are similar and this might explain how aluminum is able to enter organisms. Since aluminum is potentially toxic, it is important to be able to characterize its speciation in soln. Three major difficulties are the existence of a large no. of equil. processes, its ready hydrolysis, and the lack of suitable spectroscopic probes. One way of looking directly at the aluminum environment is by 27Al NMR, but there are difficulties with spectral assignment. A comparison of solid-state structures detd. by x-ray crystallog. with these NMR spectra offers a means of detg. which species are important components in the soln. state. With this in mind, the authors have synthesized and characterized by x-ray crystallog. two new aluminum complexes and used the information from the synthetic procedure and the structural details to interpret 27Al NMR. These components are directly analogous to the iron compds. reported by the authors previously. They are a dinuclear compd. [Al(heidi)(H2O)]2·2H2O and a tridecanuclear compd. [Al13(μ3-OH)6 μ(2-OH)12(heidi)6(H2O)6]3+. [on SciFinder(R)]