JOUI. NAT. or TlIK I'OI.T.F.CK 01' SPTI^'N» ■)•:, '!'nKV(-) IJirFKlAI. tTNTVFl.STTV 



VOL. XLI., ART. 10. 



On the Stereochemical Configuration of the 



Aquotriammine and Diammine 



Cobalt Complex Salts. 



By 



Kichimatsu MATSUNO, /.'/V//,h.s7i/. 



Introduction. 



The present investigation was undertaken to determine the 

 stereochemical configuration of the aquo-triammine and diammine 

 collait complex salts, l)y ol)serving the effects on the absorption 

 spectra exercised ])y water molecules which coordinate in place of 

 ammonia in cobaltammines in their aqueous solutions. The 

 aquocobaltammines are, in general, more soluble in water than 

 otiier cobalt-amminc's and the_y are of various colours and different 

 solubilities, according to the number of water molecules coordinated 

 .in them. The reason wliy such cobaltammines as [Co(NH3\TSÎOp.]X2, 

 [Co(NH3),(N03)jX, [Co(NH^),(NOp,)J, [Cc(NH,),CU]X„ [Co(NH,XH,0 CIJX^ 

 and [Co;]SrH3)5Br]X2 etc. , which are not soluble in cold waler 

 l)ecome readily soluble in warm water, or sliglitly acidic oi- alkaline 

 solution, is based upon the facts that tlie nitrate groups, and 

 halogen atoms are substituted by water; thus the cobaltam- 

 mines change into [Co(XH,),H,0]|^^^ [Co (NH,),(H.A\] '^^x'''' 

 [Co (NH,)3 (H.O^^] ( NO,),, [co (NH^), H/)] ^^^, . [co (NH3), (H.p),] ^f 



and Co(NH3)gH.p \^ etc. . . respectively. Therefore the study 



of the relation of water molecules with cobaltammines a])pears to 

 be of some importance. Up to the present, the following series of 



