Determination of molar refractions and Abraham descriptors for tris(acetylacetonato)chromium(iii), tris(acetylacetonato)iron(iii) and tris(acetylacetonato)cobalt(iii)

Abstract

We have determined molar refractions of tris(acetylacetonato)chromium(III), tris(acetylacetonato)iron(III) and tris(acetylacetonato)cobalt(III). Although the d-electron structures of the three metal centres differ significantly, the three molar refractions are actually quite close to each other. We then used these molar refractions to determine the Abraham E-descriptor, we calculated the V-descriptor by McGowan's method, and then used literature data on solubilities and water–solvent partitions to obtain the rest of the set of descriptors for the three tris(acetylacetonato) complexes. If we take E as the average of those for the chromium, iron and cobalt complexes, we can use limited literature data to obtain the full set of Abraham descriptors for the tris(acetylacetonates) of vanadium(III), yttrium(III), samarium(III), lanthanum(III) and neodymium(III). For the eight complexes, the descriptors vary regularly with complex molecular weight. These show that the complexes are quite polarizable, have zero hydrogen-bond acidity and significant hydrogen bond basicity. From the sets of Abraham descriptors, a very large number of physicochemical properties can be predicted for the eight acetonylacetonates.