Complex nickel nitrites. II. Linkage isomerism in complexes of ethylenediamine and N,N'-diethylethylenediamine

Abstract

Two pairs of linkage isomers, NiL₂X₂, have been prepared. When L = N,N?- diethylethylenediamine, the blue dinitrito form (X = ONO) is stable at room temperature, but the metastable dinitro form (X = NO₂) can be prepared and stored for several days as red octahedral crystals. At -60° the dinitro complex is the stable form.     When L = ethylenediamine there is a transition temperature at 74±2°. The known stable red dinitro complex is converted into a blue dinitrito isomer by heating. The blue form is metastable at room temperature but again can be stored for several days. In each case the isomerization reaction of the metastable to the stable isomer can be followed by infrared spectrometry.