Preparation, properties, and reactions of trans-chloro- and trans-bromo-isothiocyanatobis(±-propylenediamine)cobalt(III) cations

Abstract

One isomeric series of the complexes [Co(±pn)₂NCS X]SCN, where pn = propylenediamine (1,2-diaminopropane) and X = Cl and Br, have been prepared and assigned a trans configuration on thebasis of visible absorption spectrophotometry. The solvolytic aquation and base hydrolysis of these cations have been studied. The aquation is faster, and the base hydrolysis slower, than that of the corresponding ethylenediamine complexes. The results support a unimolecular mechanism for solvolytic aquation, and a bimolecular mechanism for base hydrolysis, of the halogenoisothiocyanato-complexes.