Adducts of copper (II) β-diketone chelates with phosphorus esters

Abstract

Spectrophotometric studies in the visible region have been made on benzene solutions of Cu(chelate) 2 [chelate = anion of hexafluoroacetylacetone (HFA), thenoyltrifluoroacetone (TTA), trifluoroacetylacetone (TFA) and acetylacetone (AA)] with phosphorus esters, S [S = tri- n-octyl phosphine oxide (TOPO). tri-phenyl phosphine oxide (TPPO), tri- n-butyl phosphate (TBP) and tri-phenyl phosphate (TPP)]. For each of the four phosphorus esters, the acidity of the Cu(chelate) 2 increases in the order: CU(AA) 2 < Cu(TFA) 2, Cu(TTA) 2 < Cu(HFA) 2. For each of the Cu(chelate) 2 complexes, the electron-donor ability of the phosphorus esters increases in the order: TPP < TBP < TPPO < TOPO, which is the order of increase in basicity of S. The ease in obtaining solid Cu(chelate) 2 · S complexes can be correlated with the stability of Cu(chelate) 2 · S in solution.