No abstract

Extinction measurements indicate that EDTA, even when present in 1000 fold excess (pH 1 l), cannot compete with the Fell'-complexes of l b and 2d, although the formation constant Kf for the Fe"'-EDTA complex is 102s[91. Finally, the superiority of the ligand l b becomes clear from competition experiments with 2d, in which ca. 70% of the iron(ir1) ions are complexed by l b ; however, in order to establish equilibria, the solutions require to be heated for several hours at 100°C.Our synthetic methodology allows construction of even roomier cavities by using spacers larger than the two 1,3,5-substituted benzene nuclei, e.g. 1,3,5-triphenylbenzene building blocks, as we have previously employed in another connection (cyclophanes)["I. In this respect, these macrooligocycles are also of interest for chemical reactions in cavity interiors as well as for model studies of receptors with larger guests ['].

No abstract

No abstract

A puckered ten‐membered ring consisting of nine S atoms and one Au atom occurs in the anion [AuS9]⊖. The title compound, prepared from K[Au(SCN)2] and Ph4AsSx, forms yellow, air‐stable crystals. The structures of other polysulfidoaurates are not yet known.