Contrary to suggestions in the literature, it has been proven that Al(iii) forms a 1:1 complex with gluconate (hereafter Gluc-) in strongly alkaline (pH > 12) aqueous solutions. The complex formation was proven via27Al and 1H NMR, freezing-point depression, polarimetric measurements as well as potentiometric and conductometric titrations. This complexation is a pH independent process, i.e., a condensation reaction takes place. The stability constant of the complex formed was derived from 1H NMR and polarimetric measurements, and was found to be log K = 2.4 ± 0.4. In the complex formed, Al(iii) has a tetrahedral geometry, and the Al(OH)4- is most probably statistically distributed between the alcoholate groups of the Gluc-.
ASJC Scopus subject areas
- Inorganic Chemistry