Chemistry. — Investigations into Pasteur's Principle of the Con- 

 nection hetioeen Molecular and Crystallonomical Dissymmetry : 

 IV. Racemic and Optically-active Complex Salts of Rhodium- 

 tri-o-mlic Acid. Bj^ Prof. Dr. F. M. Jaeger. 



(Gommunicaled in the meeting of June 30, 1917). 



§ 1. In our previous papers we had occasion to draw attention 

 to the fact that the crystals of the optically active components 

 which, according to Werner's theory, may be obtained under definite 

 circumstances from the racemic complex salts of the general type: 

 \Me X'W Yn, exhibit occasionally the non-superposable hemihedrism 

 to be expected according to Pasteur's principle, but that in other 

 cases of this kind no evidence whatever of this hemihedrism is 

 detectable by any experimental method at hand. 



At the same time attention was drawn to the other fact that the 

 molecular dissymmetry in cases as these, is by no means caused 

 by a total absence of symmetry-properties in the molecule, but that 

 the complex ions of the type mentioned, if once Werner's theory 

 be adopted, must possess a configuration of their radicals in space, 

 possessing the symmetry of the trigonal-trapezohedral class (Z^j). 

 From the established fact that the non-superposable hemihedrism 

 of the crystal-forms could not be stated in several cases where deri- 

 vatives of the complex tri-ethylenediamine-cobalti-ion \Co{Eijie)^\ • • • 

 were studied, we were compelled to conclude that the cause of 

 this abnormal behaviour must be ascribed to the particular circum- 

 stance that the radicals placed round the central metal-atom are 

 chemically identical here. It was remarked, however, that the 

 expected hemidedrism could be stated without exception in all cases, 

 where in the salts investigated radicals containing oxygen ^) were 

 present. 



It was of interest to study other instances of this kind. Thus such 

 analogously composed salts were chosen in the first place, as con- 

 tained the oxygen-bearing radicals immediately linked to the central- 

 atom in the form of the radicals of bivalent carboxylic acids. Our 

 choice was finally fixed upon salts derived from the complex 



I) F. M. Jaeger, Proceed. Kon. Acad. Amsterdam, 17. 1217. (1915); 18. 49. 

 (1915); Zeits. f. Kryst. u. Min. 55. 209. (1915). 



