Coumarins as ligands. Studies on metal complexes of 8-Amino-7-hydroxy-4-methylcoumarin and 7-Hydroxy-4-methylcoumarin-6-carboxylic acid

Abstract

Some platinum and rare earth metal complexes of 8-amino-7-hydroxy-4- methylcoumarin, viz. Na₂[R~(C₁₀H₂NO₃)Cl₄],H₂O, [Ir(C₁₀H₈N0₃)₂(0H)(H₂0)],- 3H₂0, [Ce(C₁₀H₈NO₃)₃(H₂O)₂I,6H₂O, and [Pr(C₁₀H₈N0₃)₃(H₂0)₂],8H₂O, and 7-hydroxy-4-methylcoumarin-6-carboxylic acid, viz. [Pd(C_llH₇O₅)₂], [Ce(C_llH₇0₅)_3- (H₂0)₂],3H_zO, and [Pr(C_llH₇O₅)₃(H₂O)₂], have been studied. These complexes have been isolated and characterized by analyses, conductometric, magnetic, and spectroscopic studies. An octahedral stereochemistry has been assigned to these complexes except for the Pd^II complex which has a typical square-planar stereo- chemistry. The visible spectra of the Pr^III complexes show characteristic f-f transitions and the nephelauxetic effect (1-β) of these transitions has been evaluated.