Thermal decomposition mechanism of bis(dipivaloylmethanato)strontium compounds containing glyme adducts

The mechanisms of the thermal decomposition of Sr(dpm)(2),Sr(dpm)(2)-triglyme, and Sr(dpm)(2)-tetraglyme, where Sr(dpm)(2) is bis(dipivaloylmethanato)strontium, were examined using thermogravimetric analysis, mass spectrometry, and Fourier transform infrared spectroscopy (FTIR). The chemical bonds in the Sr compounds are sequentially decomposed as the compounds are heated. That is, glyme adducts are decomposed at temperatures below 200degreesC, and the Sr-O and the C-C(CH3)(3) bonds are dissociated at higher temperatures, whereas the C-O and the C-C bonds remain stable at temperatures up to 400degreesC. Glyme adducts in the Sr compounds weaken the Sr-O bond between the central Sr atom and the dpm ligand, and, as a result, the Sr-O bond in Sr(dpm)(2)-glymes is dissociated at lower temperatures than the bond in Sr(dpm)(2). However, Sr(dpm)(2)-glymes are more effectively protected from degradation, thus yielding smaller amounts of residues at elevated temperatures than Sr(dpm)(2). The FTIR results suggest that a fraction of the dissociated glyme species remains bonded to the Sr compound such that the bonded species suppresses the flexibility of the dpm ligand and consequently, access of other molecules to the central Sr atom. Sr(dpm)(2)-triglyme is stabilized by glyme adducts more effectively than Sr(dpm)(2)-tetraglyme, which is thought to originate from different numbers of oxygen atoms coordinated with the Sr atom between the two compounds. (C) 2003 The Electrochemical Society.