Art. 2. -Y. Shibata and T. Maruki 



From tliesG diversities in the optical behavier of tliese com- 

 plexes, tlie author was able to determine the spacial arrangements 

 of the nitro-gronps in several nitrammine cobalt complexes. 

 Thus, the result of the investigation of the absorption spectrum of 

 diammine-dinitro-oxalo-cobalt complex [Co(NH3)2(N.02)2C20 J ' Me' 

 easily led him to ascertain that its two nitro-groups are in the 

 adjacent positions (cis-position), this complex showing only two 

 bands at a^jout 2000 and 3000 of frequencies. 



Now, if we could determine the space positions of tlie two 

 ammonia molecules in this complex, the configuration of tlie salt 

 would become quite clear, the oxalic acid-residue necessarily 

 occupying the cis-position [A. Werner, Ann., 386, 10, 1912]. 

 Further, the configuration of diammine-dinitro-oxalo-cobalt com- 

 plex having once been determined, that of its mother substance, 

 diammine-tetranitro-cobalt complex [Co(NH3)2(N02)4] ' Me', will 

 be easily ascertained, the one being readily obtainable from the 

 other by the action of oxalic acid [Jörgensen, Zeitsch. anorg. 

 Chem., 11, 440, 1896]. Thus: — 



[Co(NH3)2(N02\]Me + C.O.Ha = [Co(NH3)2(NO,)2C20,]Me + 2N0,H 

 Now, owing to the fact that there are two possibilities in tlie 

 spacial arrangements of the ammonia molecules in the complex 

 ion, w^e may express the above chemical reaction in either of the 

 following ways : — 



NH, 



NH, 



NO, 



NO« 



oxalic acid 



NO. 



NO, 



NO., 



NO. 



NH3 



(Ammonia molecules in the 

 trans-pcsition.) 



NH3 

 (I) 



