Cunfiii'u ration of Aqtiotri- and diauiuiine Cobalt Complexes. 7 



explanations to prove tlie fact tliat tlie two chlorine atoms of the 

 dichro-salt are coordinated in the tians-position. 



With regard to the contigurations of the triaquotriammine 

 cohaltic salts, we can theoretically establish two isomers: one in 

 which all the three water molecules are coordinated in the eis and 

 consecutiv'e positions and the other in which two of them are in 

 the trans-position as follows : 



NH, 



n.,0 



'NIL 



H.,0^ 



'H.O 



NH3 

 (I) 



NH, 



HO. 



'NH- 



H.,0'' 



NH,, 



(II) 



X« 



On addition of hydrochloric acid saturated at 0°C to the 

 acetic acid solution of [Co (N02)3 (NH3)3], which is kept over night, 

 [Co (HgO^s (NH,\] Cls ^'^ separates in the shape of reddish violet 

 crystals. The stereochemical configuration of this salt, tliough it 

 cannot be determined by means of ordinary chemical analysis, can 

 be ascertained by the study of its absorption spectra. With the 

 help of this recently well-developed spectrochemical method, I 

 was al)le to prove that in the above triaquotriammine cobaltic salt, 

 the three water molecules are coordinated in the eis and consecu- 

 tive positions as indicated by (II). Accordingly, there must exist 

 another isomer of the type (I). 



The position of the three ammonia molecules of the dichro 

 salt has already been proved to be as follows : 



NH, 



(1) Werner : Ber., 39, 2678, 1906. 



