Thermal Studies of Nickel(II) Squarate Complexes of Triamines in the Solid State

[NiL₂]C₄O₄·nH₂O [where n=2 when L=diethylenetriamine(dien) and N-(3-aminopropyl)-1,3-propanediamine (dpt); n=3 when L=N-(2-aminoethyl)-1,3-propanediamine (aepn); n=0 when L=N²-methyldiethylenetriamine (medien)] and Ni(tmdien)C₄O₄·2H₂O (where tmdien=1,4,7 trimethyl-diethylenetriamine) have been synthesised and investigated thermally in the solid state. Ni(dpt)C₄O₄·H₂O has also been synthesised pyrolytically in the solid state from the corresponding bis complex. All the complexes possess octahedral geometry. The squarate anion takes part in coordination only in monotriamine species. [Ni(medien)₂]C₄O₄ upon heating undergoes phase transition (270–285°C; ΔH=4.9 kJ mol⁻¹) accompanied by colour change pink to grey. Thermal stability decreases with increase in chain length of the triamines. This revised version was published online in August 2006 with corrections to the Cover Date.