Thermal properties of solid nickel(II) coordination compounds

Abstract

The paper deals with the chemical and physical factors influencing the thermal octahedral square planar changes of nickel(II) complexes in the solid phase. The relationship between these transformations and the tetragonal distortion of the octahedral ligand field is discussed. Depending on the coordination of the ligands, these transformations can be divided into two groups: octahedral monomer ~-, square planar monomer, and octahedral polymer ~ square planar monomer changes. Attention is directed only to octahedral and square planar Ni(II) complexes (square planar complexes with chromophores [NiN,], [NiN202] and [NiO,]), which can be isolated in the solid state before and after heating. The possibility of such a configurational change seems to be dependent upon the thermal stabilities of the initial and final complexes, the electronic and steric properties of the ligands, the complexing ability of the central atom, and particularly the equatorial-axial interactions of the ligands via the central atom.

Temperature induced structural changes of Cu(II) and Ni(II) complexes and their thermal decomposition

“…It was shown [11] that with increasing basicity of the ligands L (pyridine and its derivatives) and with decreasing coordination ability of the anion X (X-= C1, Br, I, C104, BF4) the probability of the formation of square-planar complexes increases [12]. …”