Six-coordinate Chromium(III) Complexes with N,N′-Ethylene-bis(acetylacetoneiminate) as a Ligand

Numerous six-coordinate chromium(III) complexes with N,N′-ethylene-bis(acetylacetoneiminate) (abbreviated as Acen) have been synthesized. The complexes obtained are of the type [Cr(Acen)X2]Y, where X=H2O, NH3, CH3NH2, n-C3H7NH2, and n-C4H9NH2 for Y=Cl and X=CN, NCS, and NO2 for Y=K. The complex [Cr(Acen)(H2O)2]Cl has been obtained by a reaction of anhydrous chromium(III) chloride with N,N′-ethylene-bis(acetylacetoneimine) in tetrahydrofuran. The other complexes have been derived from the diaquo-complex. Infrared spectra show that the nitrite ions in [Cr(NO2)2(Acen)]− and the thiocyanate ions in [Cr(NCS)2(Acen)]− are bound with the chromium(III) ion through oxygen and nitrogen atoms, respectively. Electronic absorption bands of all these complexes, which arise from internal transitions within the ligand Acen, differ greatly from those of the free ligand, suggesting that the electronic states of the ligand in the complexes differ from those of the free ligand.