Hydration behaviour of some alkyl dithiocarbonates and their mixed-ligand oxalatochromate complexes

Abstract

A series of mixed-ligand chromate complexes, K₂[Cr(ox)₂(S₂COR)]·xH₂O (ox = oxalate, R = Me, Et, Prⁿ, Prⁱ, Buⁿ, Buⁱ, Bu^s or CH₂Ph), has been isolated and characterized. From density and ultrasonic velocity measurements at 25, 35 and 45 °C of the potassium salts K[S₂COR] of the alkyl dithiocabonates and their corresponding mixed-ligand chromate complexes in aqueous solution, partial molal volumes (V₂°), partial molal adiabatic compressibilities (κ_s°) and hydration numbers (n_H) have been determined. The hydration atmospheres around the second co-ordination sphere of the complexes in solution have been examined as a function of temperature. The results have been interpreted in terms of differences in hydration behaviour of the ligands and complexes, on the basis of known hydration models.