An NMR Study of Metal Complexes Containing Acetylacetone and Related Compounds. III. The Preparation and Determination of the Configurations of Cobalt(III) Complexes Containing <i>N</i>,<i>N</i>′-Ethylenebis(acetylacetonimine) and <i>N</i>,<i>N</i>′-Ethylenebis(salicylideneimine)

Abstract

Abstract A series of cis-β-form cobalt(III) complexes containing N,N′-ethylenebis(acetylacetonimine) dianion (baen) or N,N′-ethylenebis(salicylideneimine) dianion (salen) were prepared—cis-β-[Co(X)(Y)] and cis-β-[Co(X)(Z)]ClO4(where X=baen or salen, Y=anions of acetylacetone, benzoylacetone, 8-hydroxyquinoline, and Z= ethylenediamine, 1,10-dipyridyl, 1,10-phenanthroline). The synthetic methods and characterization data are given. Also prepared were a series of trans-form cobalt(III)-bean complexes—trans-[Co(X)(A)2]ClO4 and trans-K[Co(X)(NO2)2] where X=baen, and A=ammonia, methylamine, pyridine, aniline). The isolation of only cis-β-form complexes in reactions between [Co(X)(H2O)2] and the bidentate ligands contrasts with the isolation of only trans-form ones in those between [Co(X)(H2O)2] and the monodentate ligands. This result was explained in terms of the relative stabilities of the three configurations of the coordinated baen and salen. On the basis of the configurational analysis, the relative stabilities of the three configurations were determined to be trans-planar form &amp;gt; cis-β form &amp;gt; cis-α form.