Thermal Reactions of Octahedral Nickel(II) Complexes Containing N,N- and N,N′-Dialkylethylenediamines in a Solid Phase

Abstract

Thermal reactions of the [Ni(H₂O)₂(AA)₂]X₂·nH₂O complexes in a solid phase were investigated, where AA is N,N′-diethylethylenediamine (NN′-deen), N,N-dimethylethylenediamine (NN-dmen), or N,N′-dimethylethylenediamine (NN′-dmen), and where X⁻ is Cl⁻, Br⁻, I⁻, NO₃⁻ or ClO₄⁻. By means of thermal analyses and spectral and magnetic measurements in a series of these complexes before and after heating, the following results were obtained. In the case of the NN′-deen complexes, only the perchlorate deaquates to change from octahedral to square-planar, but the other salts, such as the chloride, bromide, iodide, and nitrate, undergo deaquation-anation keeping their octahedral configuration. The deaquation-anation was also observed in the chloride, bromide, and nitrate of the NN-dmen complexes, but the iodide deaquated, and so was transformed from octahedral to square-planar. In the NN′-dmen complexes, only deaquation-anation was detected, irrespective of the anions (Cl⁻, Br⁻, I⁻, and NO₃⁻). The effects of N-substituents in the diamines and the anions on the above transformation were discussed.