Contii>'uratioii of A«iviotvi- ami diauiuiinu Colialt Complexes. 



9 



a sliort time, it produces readiW t1io st;il)lo cis->alt. Accordingly, 

 one is much inclined to the conchisiou that the cis-aquocompounds 

 are as a rule more stable than tlie corresponding trans-compounds 

 in aqueous solution. 



Now that I have described the structures of the cobalt 

 complex salts of tlie triammine series, I shall discuss the configu- 

 rations of those of tlie diammine series. As tlie stereochemical 

 structure of one of these salts, i.e. the tetranitrodiammine cobaltic 

 salt [Co (NOa^ (NH3)2] K, a starting substance of these series, has 

 been thoroughly investigated by Y. Shil:)ata^'^ and the late 

 T. Maruki, no further confirmation as to it is necessary. 

 In this salt the two ammonia molecules are coordinated in the cis- 

 position as follows : 



NO., 



NH, 



-7 NH;,, 



ÎCO-, 



NO.. 



When [Co ÇS^O.^^ 'vNH3)2] K ^-^ is treated with a cold mixture of 

 strong hydrochloric acid and sulphuric acid, a malachite green 

 salt [Co CI2 (HsjO)^ (NH3)2] SO4 H is produced, and on this salt being 

 dissolved in water acidified with H2 SO4 and evaporated in 

 the desiccator over sulphuric acid, indigo blue crystals of 

 [Co CI (H.^0\ (NHs)^] SOi-H.O separate out. If the latter is acted 

 upon by strong hydrochloric acid, it changes into a greenish 

 powder which corresponds to the formula [Co Cl2(H20)2 (^Hs)»] CI ^^\ 



From tliese reactions, we can now deduce tlieir constitutions 

 as l)elow. With respect to [Co CI2 (HjOjj (NH3)2] X, we are able 

 theoretically to derive the following three configurations : — 



(1) Journ. College of Science, Imp. Univ. Tokyo Vol. XLI., Art. 2, 1917. 



(2) Jörgensen : J. prakt. Chetu., [2] 23, 249, 1881. 



(3) Werner : Zeit, anorg. Cheui., 15, 16.5, 1897. 



