Thermally induced isomerisation and decomposition of diethylenetriamine complexes of nickel (II) in the solid state

Abstract

Complexes [NiL₂]X₂•nH₂O (L = diethylenetriamine; n = O when X = CF₃CO₂ or CCl₂CO₂; n = 1 when X = Cl or Br and n = 3 when X = 0.5SO₄ or 0.5SeO₄) and NiLX₂•nH₂O (n = 1 when X = Cl or Br; n = 3 when X = 0.5SO₄ or 0.5SeO₄) have been synthesised and investigated thermally in the solid state. NiLSO₄ was synthesised pyrolytically in the solid state from [NiL₂]SO₄•[NiL₂]X₂(X = Cl or Br) undergo exothermic irreversible phase transitions (242–282° C and 207–228° C; ΔH = −11.3 kJ mol⁻¹ and −1.9 kJ mol⁻¹ for [NiL₂]Cl₂ and [NiL₂]Br₂, respectively). [NiL₂]-phenomenon (158–185° C; ΔH = 2.0 kJ mol⁻¹). NiLX₂• nH₂O (n = 1 or 3) undergo simultaneous deaquation-isomerisation upon heating. All the complexes possess octahedral geometry.