Relative stability constants of the uranyl tropolonate system with neutral ligands in benzene

Abstract

The relative formation constants K_L* of some uranyl tropolonate adducts with neutral ligands L (L = cyclopenta-none, pyridine, dimethyl sulphoxide, 4-chloropyridine N-oxide, 4-methylpyridine N-oxide, triphenylphosphine oxide, and triphenylarsine oxide) of general formula [UO₂(trop)₂L](Htrop = tropolone) have been determined spectrophotometrically by studying the equilibria [{UO₂(trop)₂}₂]+ 2L ⇌ 2[UO₂(trop)₂L] in benzene at 25 °C. The K_L* sequence obtained can be used as a quantitative scale of donor ability of the various neutral ligands toward the common substrate. Other attempted qualitative correlations based on i.r. ¹H n.m.r. and thermal measurements are compared and discussed.