Studies of Complexes of the Transition Metals IV. Cobalt Complex with Dithiomalonate

The cobalt (II) ion and the dithiolmalonate ion form a complex which is reasonably stable in aqueous solution and highly colored. Studies were conducted by means of spectrophotometric methods in the visible region. The composition of the complex and the overall formation constant were determined using the method of continuous variation of Job and successive dilutions of stoichiometric proportions of the ligand and metal. All measurements were made at room temperature with the solutions kept at a constant ionic strength of 0.1. The results indicate the composition of the complex to be that of three moles of ligand to one mole of cobalt. The formation constant obtained is lower than that of the cobalt dithioloxalate complex, indicating that the six membered ring is less stable than a similar five membered ring