Adducts of copper(II) b-diketone chelates with heterocyclic bases. II. Chelates with 3-alkylacetylacetones

Abstract

Copper(II) chelates have been prepared from a series of 3-alkylacetylacetones, R(acac) (R = CH₃, C₂H₅, n-C₄H₉, n-C₇H₁₅, n-C₁₆H₃₃, and CH₂C₆H₅). Their absorption spectra have been examined in the solid state and in solution in benzene and heterocyclic bases. Formation constants for 1 : 1 adducts with pyridine, 2-methyl-pyridine, and 4-methylpyridine are smaller than those for Cu(acac)₂ and not affected by variation of R. Analysis of the absorption spectra throws further light on the assignment of absorption bands in the ligand field region. Instability of solutions of the chelates in heterocyclic bases is due to cleavage of the β-diketones with the formation of acetate, followed by further decomposition of unknown nature.