Chemistry — "-On some isomeric, complex cis- and trans- Diethy- 

 lenediamine- Salts of Cobaltum, and on Tri-ethylenediamine- 

 Zinc- Chloride." By Prof. Dr. F. M. Jaeger and Dr. Jul. Kahn. 

 (Communicated in the meeting of June 30, 1917) 



§ 1. According to Werner's theory concerning tlie slereometrical 

 conlignration of inorganic sails derived from tiie complex radical : 

 \MeX\], there must exist two isomerides of derivatives containing 



ions of the special type : f Me ' J , which are distinguished as cis- 



and ^?v)r/i5-isomerides. If the six co-ordination-loci round the central 

 atom be considered as situated in space like the six corners of 

 a regular octahedron, the substitutes Y' are located in the cis- 

 derivatives as near as possible to each other, while, on the contrary, 

 in the /7Yi?w-derivatives they are elongated as far as possible from 

 each other, being placed at the two ends of an xixis of the octahedron. 

 If in the complex salts of this kind, the four co-ordination-loci 

 X\ be occupied by two bivalent radicals X'\, it is obvious that 

 the configuration of the molecule in the m-derivatives possesses the 

 a.i/a/ symmetry of C\ ; the heteropolar binary symmetry -axis of these 

 complex ions joins of course the middle of the octahedron-edge Y' Y' 

 with that of the opposite and parallel edge. The symmetry of these 

 ions is therefore exactly that of the monoclinic-sphenoidical class of 

 crystallonomy and to every configuration of this kind corresponds 

 therefore a /w/z-superposable mirror-image, because the complex of 

 atoms possesses only axial symmetry. The cw-compounds of the type 



Y' \ 



Me '1 must, for that reason, be considered as racé;;/?ic compounds 

 X ,J 



( 



eventually resolvable into two optically active and oppositely rotating 

 antipodes. The possibility of such a fission is demonstrated by Werner 

 in an experimental way for several salts of this kind. 



The ^ran^-derivatives of the same type ( Me ' J, however, 



IT 



possess the symmetry of the group D^ . Their configuration is there- 

 fore identical with its mirror-image, so that they are not resolvable 

 into such antipodes. ^) 



') See: F. M. Jaeger, Lectures on The Principle of Symmetry and Its Appli- 

 cations in all Natural Sciences, Elsevier-Gompany, Amsterdam, (1917), p. 228 — 256. 



