Complex formation of beryllium(II) with salicylate and hydroxide ions in 1 mol dm–3 sodium perchlorate aqueous solution at 25 °C

Abstract

The complex formation of Be²⁺ with salicylate (L^2–) and hydroxide ions was investigated at 25 °C in 1 mol dm^–3 NaClO₄ by potentiometry using a glass electrode. The e.m.f. measurements were performed under the conditions 2.7 ⩽–log [H⁺]⩽ 8, 0.002 ⩽c_M⩽ 0.01 mol dm^–3, 0.002 ⩽c_L⩽ 0.015 mol dm^–3, and 1 ⩽c_L/c_M⩽ 7, where c_M, and c_L, denote the total concentrations of Be^II and salicylic acid, respectively. The e.m.f. data were explained with the three major species [Be(HL)L]^–, [BeL], and [BeL₂]^2– and at least one or even all of the four minor species [Be(HL)]⁺, [Be(HL)₂], [Be(OH)L]^–, and [Be₃(OH)₃L₃]^3–. The hydrolytic reactions of Be^II in 1 mol dm^–3 NaClO₄, data on which were used for the analysis of the above beryllium(II)–salicylate-hydroxide system, were also studied by separate potentiometric titrations. It was found that [Be₂(OH)]³⁺, [Be₃(OH)₃]³⁺ and [Be₆(OH)₈]⁴⁺ occur in 1 mol dm^–3 NaClO₄ aqueous solution.