Luteo series

Despite Werner s antipathy for names based on color, such names were generally used well into the present century. For example, the name luteo, originally proposed for [Co(NH3)6]", was generalized to include [Co(en)3] [Co(bipy)3] [Co(trien)2] and other cobalt compounds in which six amine nitrogen atoms are coordinated to cobalt (or even other metal ions) in the luteo series. As long as cobalt and chromium were the only metal ions included, the reference to color had real meaning. However, to consider colorless [Ru(NH3)6]" (16) as a member of the luteo series was, to say the least, somewhat ambiguous. 

The series was discovered by Jorgensen in 1879,1 and in 1881 Christensen2 established the constitution of the substances. The salts are prepared by the decomposition of the ehloro-purpureo-chromic salts. They are orange-yellow in colour and less stable than the luteo-salts. They form double salts like the luteo-salts, the most characteristic of these being the sparingly soluble ferricyanide and the sulphato-chloroplatinate. 

In 1892 Jorgensen 1 discovered a series of polynuclear chromic ammines which he obtained as by-products in the preparation of luteo-chromic salts. These he called Rhodoso-chromic salts. Later, in 1901, Pfeiffer 2 prepared by the same method rhodoso-chromic salts containing ethylenediamine in place of ammonia. The constitution of the rhodoso-salts is, however, still somewhat doubtful. Jorgensen gave to the compounds the constitutional formula... 

Vanado-arsenates.—The salts of this class which have hitherto been prepared are all of low vanadium pentoxide content compared with the amount of arsenic pentoxide present. They correspond, therefore, to the luteo vanado-phosphates. Three series are known. The... 

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