OBSERVATIONS ON RARE EARTHS .79. SYNTHESES AND PROPERTIES OF ETHYLENEDIAMINE CHELATES OF TRIPOSITIVE LANTHANIDE IONS

Under carefully controlled experimental conditions and with maintenance of completely anhydrous systems, the direct reaction of ethylenediamine with a lanthamde(III) salt in acetonitrile yields solid compounds of the stoichiometric compositions Ln(en)3X3 and Ln(en)4X3, where X = NO3, Cl, Br, or C1O4. Infrared data establish coordination by the anion in several of the solid complex compounds. Although the 20% decrease in metal ion radius across the lanthanide series does not affect the number of ethylenediamine molecules bonded to an Ln3+ ion, the space available for coordination by an anion is affected, and selectivity in terms of anion size is demonstrated. The result is variation in total coordination number of the cation from 9 to 8. © 1969, American Chemical Society. All rights reserved.