4 Art. 2.— T. Shibata and T. Maruki : 



extreme fractions were both proved to be opticall}' active, as had 

 been anticipated, and the one was found to be the optical antipode 

 of the other, having the foUowing specific rotatory power: 



[«]p = ±115°. 



The possibility of the mesotomisation of this complex shows 

 that it is asymmetrically constructed and that, therefore, its two 

 ammonia molecules must be in the adjacent positions, correspond- 

 ing to the space formula (I) (see page 2). Consequently the 

 position of the two ammonia molecules in diammine-tetranitro- 

 cobalt complex, the mother substance, must also be adjacent. 



The mesotomisation of diammine-dinitro-oxalo-cobalt com- 

 plex not onl}" affords us a means of determining its configuration 

 in the manner above described, but it also offers us some inter- 

 esting facts concerning tlie stereocliemistry of metal complexes. 

 In so far as this asymmetrically constructed complex ion is found 

 to be an anion, this is virtually the first example of a mesotomised 

 complex anion containing a cobalt atom^'\ the large number of 

 optically active cobalt complexes Intherto obtained bj^ A. Werner 

 and his pupils being all of them cations. Moreover the type of 

 the optically active anion [Co(NH3)2(N02)2C204] ' is entirely new in 

 respect to the molecular asymmetry of such metal complexes. 



When A. Werner found optical activity in some cobalt- 

 ammine complexes, he drew attention to the fact that the activity 

 is due sometimes to the asymmetric cobalt atom, sometimes to an 

 asymmetric structure of the complex ion as a whole. Those in 

 which optical activity is due to the asjmimetric structure of the 

 complex ion as a whole were further classified by him into the 

 two types [MeAsBy (or [MeA.C']) and [MeAg]^'', calling them 

 respectively the type of molecular asymmetry I and the type of 

 molecular asjnnmetry II. For example, cvVdinitro-diethylene- 

 diamine-cobalt complex [Coen2(N02)2(2)]', and carbonato-diethylene- 



1) A. Werner mesotomised formerly a chromium complex containing- a complex anion 

 [Cr(C204)sJ". [Jier., 45, 30Ü1, 1912]. 



2) In these general formulae, A means a molecule of organic amine ))ases which cor- 

 responds to two molecules of ammonia, or a bivalent acid radical, while B and C represent 

 respectively mono-and bivalent acid radicals. 



