Cobalt(III) di-carboxylato(bis)-ethylenediamine nitrates: preparation and characterization by thermal analysis and other analytical methods

Compounds with the general formulacis ortrans-[Coen 2 (RCOO)2]NO3 were prepared by modifications of known procedures; R was H, CH3, C2H5 or C3H7, anden was ethylenediamine. The compounds were characterized by TLC and UV-Vis spectrophotometry, and their thermal behaviour was examined via TG and DTA, and via IR spectra on heated samples. The thermal stabilities are discussed in terms of the strengths of the bonds in the solids [1] and steric hindrance; the thermal decompositions are described with the aid of hypothesized intermediates and IR spectra. Reaction steps are identified and the thermal stability sequence is discussed: thecis compounds are less stable than the correspondingtrans compounds, due to the lower reticulation effect; the sequence of thecis compounds is the reverse of the sequence of carboxylate ion basicity, while the sequence displalyed by thetrans compounds can be interpreted in terms of solid lattice stabilization.