Thermal decomposition of oxovanadium(IV) complexes with N,N '-ethylenebis(amino acids)

Six oxovanadium(IV) complexes with N,N'-ethylenebis(amino acid) of general formula, [VO(XeX)(H2O)]. nH(2)O, where e and X represent ethylene group and (S)-alpha-amino acid, respectively; and X=G (Gly) 1, (S)-A (Ala) 2, (S)-V (Val) 3 . 2H(2)O, (S)-P (Pro) 4, (m)G or G(m) (Sar or N-methylglycine) 5 . H2O and (S)-M (Met) 6) were prepared. These complexes were characterized by means of TG, DTA, and XRD, and the thermal decomposition processes of thes e complexes up to 650 degrees C were investigated. The thermal studies show ed that the dehydration processes for 3 and 5 having water of crystallizati on were endothermic, whereas decompositions of all the complexes were exoth ermic. Calcinations of these complexes at 650 degrees C resulted in the for mation of vanadium(V) oxide V2O5. Choosing 1 as a leading example of the ox ovanadium(IV) complexes, an over all reaction scheme for the thermal decomp osition was proposed on the basis of IR and MS analyses of both the solid a nd the volatile decomposition products at different temperatures. (C) 2000 Elsevier Science Ltd. All rights reserved.