Measurements of binary diffusion coefficients for metal complexes in organic solvents by the Taylor dispersion method

Abstract

Infinite dilution binary diffusion coefficients, D 12, of ferrocene, 1,1′-dimethylferrocene and ethylferrocene in hexane, cyclohexane and ethanol at 313.2 K and pressures from 0.2 to 19 MPa, in acetonitrile at 298.2–333.2 K and 0.2 MPa, and various metallic acetylacetonate, acac, complexes such as Co(acac) 3, Ru(acac) 3, Rh(acac) 3, Pd(acac) 2 and Pt(acac) 2 mainly in ethanol at 313.2 K and 0.2 MPa were measured by the Taylor dispersion method. The D 12 values in m 2 s −1 for the three ferrocenes in the present study and those of ferrocene and 1,1′-dimethylferrocene in supercritical carbon dioxide in our previous studies were represented by the modified hydrodynamic equation over a wide range of viscosity: M 0.5 D 12/ T = 1.435 × 10 −13 η −0.8446 with average absolute relative deviation of 2.40% for 316 data points, where M is the solute molecular weight, T is the temperature in K, η is the solvent viscosity in Pa s. Although the D 12 values for the acac complexes were roughly represented by the above hydrodynamic equation, the accuracies were lower because they were dependent on not solute molecular weight but the number of acac ligand in the complex molecules.