The Viscosities of Aqueous Solutions Containing Metal Complexes. I. Luteo-type Co(II) and Co(III) Complexes and Ethylenediaminetetraacetato Complexes

Abstract The viscosities of aqueous solutions containing cobalt complexes formed with ammonia, ethylenediamine (en), propylenediamine (pn), 2,2′-bipyridine (bip), 1, 10-phenanthroline (phen), and ethylenediaminetetraacetic acid (H4edta) were determined with a Cannon-Fenske capillary viscometer. Measurements were made in a Shibata viscosity bath maintained at 25±0.01°C. The Jones-Dole viscosity B-coefficients of Co(III) complex cations formed with NH3, en, pn, bip, and phen increase in that order. There is no significant difference between the B-coefficients of [Cobip3]3+ and [Cobip3]2+, or [Cophen3]3+ and [Cophen3]2+. On the other hand, a pronounced difference is found between the B-coefficients of [Coedta]− and [Coedta]2−. This might suggest that there is a marked difference in the structure of [Coedta]− and [Coedta]2− anions.