Chromium(II) salts in the synthesis of chromium(III) chelates with beta-diketonate ligands

Chromium(III) chelates of the general formula Cr(CH3COC(Alk)COCH3)(3), wher e Alk = Me, CH2CH=CH2, CH2Ph, were synthesized by the reaction of alpha-alk ylacetylacetones with chromium(III) hexahydrate in aqueous ethanol in the p resence of a strong base (sodium hydroxide). Boiling of the solution of lig and and chromium(II) salt prior to addition of the base results in improved yield of the chelate. A new method for preparing chromium(III) chelates fr om chromium (II) salts is developed, which provides higher yields of chromi um (III) alkylacetylacetonates and makes it possible to prepare chromium(II I) chelates with hydrolytically unstable ligands. The versatility of the pr oposed procedure is proved by the synthesis of chromium(III) monothioacetyl acetonate Cr(CH3CSCHCOCH3)(3) in high yield.