253 



by a rhodium-atom, is, therefore, manifested only by the change in 

 magnitude of the specific rotation, but not by a change of its 

 direction. As long as no urgent experimental data are available to 

 compel us into another way, it is of importance to construct our 

 plan of the mutual dependence of natural phenomena as simply 

 and transparently as possible; and the conception of the relations 

 between optical activity and configuration of molecules, as explained 

 in the above, seems to us really a simpler and more perspicuous one 

 than that proposed by Werner. For this reason the algebraic signs 

 of the rotation of the rhodium-salts are here taken identical with 

 those of the corresponding cobalti -salts l ). 



In a recent paper, Smirnoff 2 ) demonstrated, that the introduction 

 of three molecules of one of both possible optically active x-pro- 

 pylenediamines into the complex ions of platinum-, or cobalti-sa\ts 

 of the same type as was dealt with here, has the remarkable 

 effect that to each of both optically active diamines only one of 

 the two possible, enantiomorphous spatial configurations of the 

 complex ion corresponds, the number of isomerides obtained 

 in this way being, therefore, reduced to two in stead of four. From 

 this fact it must be also concluded that the spatial arrangement 

 of the substitutes round the central metallic atom of the complex, 

 is determined by the special molecular symmetry or dissymmetry 

 of those substitutes themselves, and that the molecular dissym- 

 metry of the three substitutes will, therefore, determine, which of 

 the two possible enantiomorphous configurations of the complex 

 will be exclusively assumed in each case. This fact is wholly com- 

 parable with a "partly asymmetrical synthesis" of an inorganic 

 molecule, which synthesis is of the same type as that of organic 

 compounds, considered more in detail in the last chapter of this book. 



20. From the foregoing it is evident that for the considerations 

 regarding the eventual possibility of the separation of a chemical 

 substance into two enantiomorphously related antipodes exhibiting 

 opposite rotatory power, the question as to the special stereometrical 

 configuration must in each case be brought to the fore. If the con- 

 ception of Van 't Hoff and Le Bel as to the direction of the four 

 carbon- valencies be adopted, and, keeping that in mind, the stereo- 

 metrical "model" of the molecule be constructed, we have only 



!) F. M. Jaeger, Proceed. Kon. Akad. v. Wet. Amsterdam, Vol. 20, 264, 265, 

 (1917); Chemisch Weekblad, 14, 728, (1917). 



2) A. P. Smirnoff, Helvet. Chimica Acta, 3, 177, (1920). 



