Polarographic studies on the interaction between macrocyclic compounds and cations or acids in acetonitrile

Abstract

At the DME, 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane (Me 4[14]aneN 4, TMC) in acetonitrile containing 0.1 mol dm −3 Et 4NClO 4 as the supporting electrolyte gave a single anodic (mercury dissolution) wave at −0.41 V vs. Ag/0.1 mol dm −3 AgClO 4+MeCN electrode. The reversible anodic wave is attributed to the reaction: Hg+TMC ⇌; [Hg(tmc)] 2+ + 2 e −. The formation of the [Na(tmc)] + complex has been clarified, and the formation constant of the complex obtained not only by the shift in E 1 2 of the anodic wave from TMC but also by that of the cathodic wave of [Hg(tmc)] 2+ (produced by the addition of Hg(ClO 4) 2 to TMC) in the presence of a large excess of Na +. By the addition of a large excess of benzoic acid (HA) to the TMC solution, the TMC(H +) 2(A −(HA) 2) 2 species was formed. 1,4,8,11-Tetrathiacyclotetradecane ([14]aneS 4, TTCT) and [16]aneS 4-3,11-diol also gave single anodic waves at more positive potentials to form mercuric complexes. Oxygen-substituted compounds, 18-crown-5 and 12-crown-4, gave incomplete anodic waves.