Existence of Cupric Hexammino Sulphate

Abstract

WHILE the hexammino compounds of the halides, nitrates and other salts of copper are well known, nothing seems to be on record regarding the existence of cupric hexammino sulphate. In recent communications, Dey and Bhattacharya¹ have described a new method for the isolation of cupric pentammino sulphate, from ammoniacal solutions of cupric sulphate. In other publications from this laboratory, Dey has recorded the results of the conductometric measurements of mixtures of cupric nitrate² or chloride³, with ammonium hydroxide solutions, of various compositions. The conductometric curves gave breaks corresponding to three, four, five and six molecules of ammonia for one molecule of the copper salt, thus affording the evidence for the existence of tri-, tetra-, penta- and hexa-ammino cupric compounds. In the case of cupric ammino sulphates, however, the triammino compound is not found, whereas the three other compounds are formed. The changes in the extinction coefficients of mixtures have also been studied by means of a Nutting's spectrophotometer, and the results confirm those obtained by the electrical conductivity method. We thus find that these results indicate the definite existence of cupric hexammino sulphate, as well, in an ammoniacal solution of cupric sulphate.