The nature of the compounds alleged to be trans-dichlorobis-(1,10-phenanthroline)cobalt(III) chloride and trans-dichlorobis-(2,2′-bipyridyl)-cobalt(III) chloride

Abstract

The materials previously described as trans-[Co bipy₂Cl₂]Cl (bipy = 2,2′-bipyridyl), and still being used as such, are shown to be either reasonably pure preparations of cis-[Co bipy₂Cl₂]₂[CoCl₄] or complex mixtures (probably mixed phases) containing the cations cis-[Co bipy₂Cl₂]⁺, [Co bipy₃]³⁺, and cobalt(II) anions such as [CoCl₄]^2–. Proof is given from the results of chemical, magnetic, and spectroscopic studies and X-ray powder photography. Similarly, a green ‘compound’ described as [Co phen₂Cl₂] Cl,2HCl (phen = 1,10-phenanthroline) and since used as a source of the trans-cationic complex is shown to be [Co phen₃][phenH][CoCl₄]₂,HCl, cis-[Co phen₂Cl₂][CoCl₃(H₂O)]HCl,2·5H₂O, cis-[Co phen₂Cl₂]₂[CoCl₄], 1·5H₂O, or mixtures of these with cis-[Co phen₂Cl₂]Cl,3H₂O, depending on the mode of preparation. Preparations of various crystalline modifications of the compounds [Co chelate₃]₂[CoCl₄]₃, [Co chelate₂Cl₂]₂[CoCl₄], and [Co chelate₂Cl₂][CoCl₃(H₂O)] also are noted.