Configuration or Aiiiotri- and diainiuinL" Colnilt Complexes. 



21 



wliich suggests that its three water iiiolecules ctxH^h^iiate in tlie 

 eis and consecutive position, thus: — 



H„0 J XH, 



H,0* 



H,0 



ROi 



As a consequence, tlie structure of [Co CI2 (HgO)^ (NH3)2] SO4H 

 could also be determhied, as has been already mentioned. ïlie 

 compound [Co CI2 (H20\(NH3)2] SO^H has at first a green colour in 

 aqueous solution, but this changes gradually until its colour 

 becomes indigo blue. This change of colour is a proof that the 

 following substitution takes place : 



NH3 



ci 



.NH3 



H.O' 



H,0 

 (green) 



NH, 



SO4U 



n„o . 



.NH, 



ILO Cl 



H,,0 

 (indigo blue) 



SO4 



The cui-ve of [Co (^113)3 (HsOjg] CI3 (7) is ver}^ different from 

 that of [Co (NH3)3 (HsO)^] CI3 (8), which is the best verification that 

 the two salts are isomeric; and the former is very stable in water. 

 It is prepared from [Co (NH3)3 (N03)3] the configuration of the 

 latter will be as follows : 



NH, 



KO, 



NH3 



JiO,' 



NH, 



NO, 



