Thermal investigation of some mixed-ligand copper(II) chelates containing 1,2-diamines and beta-ketoenols

Thermal studies by TG/DTA and/or TG/DTG techniques of some mixed-ligand cop per(II) chelates were carried out to determine their stabilities and modes of decomposition. The chelates have the formula [Cu(beta -dione)(enR)]X, wh ere beta -dione is the anion of a beta -ketoenol, enR is N,N'-substituted a ryl or alkyl ethylenediamine and X is NO3- or ClO4-, while the geometry of the ensuing chromophore CuN2O2 is square-planar. The degradation processes depend on the anions and the substituents of the ligands. The nitrate compo unds are decomposed until the stable oxide, CuO, is formed at similar to 56 0 degreesC in both air and nitrogen. The perchlorate compounds, however, ar e strong explosives in air and vigorously loose almost all their weight in one step. Ln nitrogen, the thermal profile changes dramatically and instead of explosion a decomposition process takes place affording a metallic resi due at similar to 800 degreesC. Mass spectrometry (MS) was also used to giv e possible fragmentation patterns. (C) 2001 Elsevier Science B.V. All right s reserved.