Studies on Mixed Chelates. XXII. Five-Coordinate Copper(II) Chelates with N,N,N′,N″,N″-Pentamethyldiethylenetriamine and β-Diketonates

Mixed Cu(II) chelates with N,N,N′,N″,N″-pentamethyldiethylenetriamine (pmdt) and five β-diketonate (dike) ligands, i.e., dipivaloylmethanate (dipm), acetylacetonate (acac), pivaloyltrifluoroacetonate (pfac), trifluoro- and hexafluoroacetylacetonate (tfac and hfac, respectively), were prepared and studied. Their general formula, [Cu(dike)(pmdt)]ClO4, suggests that they are five-coordinated; X-ray crystal analyses confirmed that the chelates with acac and tfac are distorted square pyramidal, with the axial site occupied by one of the O atoms of dike. Similar structures are presumed for the remaining chelates on the basis of spectral similarities. In solutions, these five-coordinated chelates are solvated to various extents, showing a characteristic solvatochromism.