Coordination chemistry optical isomerism

Oxalate (ox, 204 ) complexes of Cr° have been known since the very beginning of coordination chemistry. Thus, the resolution of chiral [Cr(ox)3] with strychninium counterion by Werner in 1912 prodnced the first optically active anionic coordination compound. There also exists a series of bis(oxalato) complexes of the type [Cr(ox)2X2] + , where X can be any of a variety of nentral donors (e g. H2O, NH3, etc.) or anionic ligands (e g. SCN, N3, etc.). These compounds have been used to study the mechanism of cis/trans isomerization and racemization of optically active octahedral coordination compounds. 

Alfred Werner was born in 1866 and died from arteriosclerosis in 1919, He started as an organic chemist and finished his chemical career in 1915 as one of the foremost inorganic chemists,. He won the Nobel Prize in 1913, During a period of two and a half decades he published 174 papers and supervised the work covered by 200 doctoral dissertations, Werner was the founder of coordination chemistry. He rejected the then prevailing concept formulated by Kekule) that the valence of an element is invariable and introduced instead the notion of principal and auxiliary valence. He also formulated the concept of coordination number, Werner used both the inductive and the deductive methods of reasoning. Most of his predictions on geometrical and optical isomerism were verified by experiment. 

---