Mesoto Ulisation of Diammine-dinitro-oxalo-cobalt Complex. 



3 



^^H, 



NO 



"NO, 



NH. 



or 



oxalic acid NO., 

 > 



NH, 



NO., 



NO. 



NO., 



(Auiuionia molecules in the 

 cis-position.) 



CoO^ 



(II) 



The clioico between these two formulae for diammine-clinitro- 

 oxalo-cobalt comjDlex offers little difficulty, when we trake their 

 constructions into account. As may be seen, formula (I) is con- 

 structed quite symmetrically, which allows no possibilit}^ of the 

 existence of enanthiomorphs, while with formula (II), the con- 

 struction of which is obviously as^'mmetric, the resolution of the 

 complex into optically active isomers has to be expected. 



Accordingly, mesotomisation of diammine-dinitro-oxalo- 

 cobalt complex has l)een tried, with the result that both of the 

 optical isomers have actually been obtained. Details of our pro- 

 ceedure will be described in the experimental part, but its essential 

 points may here be outlined. The collait complex, which was 

 initially prepared as an ammonium salt, Avas first transformed into 

 the corresponding barium salt. To a concentrated solution of 

 this salt, sulphate of an alkaloid, such as brucine, strychinine or 

 cinchonine, was added, the precipitated barium sulphate was 

 filtered off. and the alkaloid salt of the complex, which readily 

 ciystallised out from the filtrate, was then fractionated in the 

 usual manner. 



The most easily and difficultly .soluble portions of the alkaloid 

 complexes, which were thus obtained by repeated fractionations, 

 were then converted into the potassium salts by the action of 

 potassium iodide. The two potassium diammine-dinitro-oxalo- 

 cobaltiates [Co(NH3)2(N02)2C204]K thus obtained from the two 



NH, 



