Ion-exchange evidence for the polynuclear ion tris[hydroxoberyllium(II)]

Abstract

The original ion-exchange distribution method for measuring ionic charge, limited to species present at low concentration relative to a reference ion, has been modified for use with high concentrations of the unknown ion. Limitations of this ‘inverse’ method have been assessed by measuring the charges of a number of well known ions. A beryllium hydrolysis polymer has been characterized in dilute perchlorate solutions effectively free from other electrolytes. In these slightly acid solutions (pH 5·5) the predominant polymeric species has a charge of +3 and a ‘metal atom-to-charge ratio’ of one. This identifies the ion as the trimer [Be₃(OH)₃]³⁺, originally proposed by Kakihana and Sillén on the basis of potentiometric evidence.