Solubility of β-diketonates, cyclopentadienyls, and cyclooctadiene complexes with various metals in supercritical carbon dioxide

The solubility of a variety of metal acetylacetonate, tetramethylheptanedionate, cyclopentadienyl and cyclooctadiene complexes in supercritical carbon dioxide was measured. The complexes included the metals potassium, rubidium, titanium, zirconium, vanadium, chromium, manganese, iron, ruthenium, osmium, cobalt, rhodium, nickel, palladium, platinurn, copper, silver, and zinc. The solubility experiments were carried out with a dynamic-gravimetric method at 333 K in the pressure range from 10 MPa to 30 MPa. The pressure dependence of solubility is presented and the influence of the ligand is discussed. The influence of the metal on solubility was investigated systematically in terms of the oxidation state of the metal, the size of the metal atom and the magnetic moment. The solubility of metal complexes depends on the ligand as well as on the metal atom. An increase in solubility can be observed with increasing number of ligands per centre atom and with increasing oxidation state. In an identical complex structure, solubility is influenced by the molecular size and the valence electron configuration of the metal centres. (C) 2006 Elsevier B.V. All rights reserved.