Thermochemical measurement of the ligand field splitting energies for hexaammine complexes of Mn(II), Fe(II), and Zn(II)

Abstract

Various lower ammines and high-energy modifications of lower ammines of the sulphates of Mn(II), Fe(II), and Zn(II) have been prepared and their heats of solution have been measured. For each of these ammine systems, the maximum difference in heat of solution, expressed in kcal/mol of heptaammine, has been found to be of the right order of magnitude to be regarded as the ligand field splitting energy for the hexaammine complex of the metal ion.

Reactions of hexakis(acetonitrile)iron(II) hexafluorophosphate in acetonitrile. Ligation of ammonia, pyridine, and trimethylamine to iron(II) and the behaviour of trimethyl phosphite and trimethylphosphine towards iron(II), nitrogen donor ligand complex cations

“…The [Fe(NH,),]'+ cation can be recovered unchanged after dissolution of [Fe(NH,),]-[PF,], in MeCN; this is similar to the situation in liquid NH,. 5 The cation [ F e ( ~y ) ~] ~' looses py in MeCN solution and the analysis of the colourless solid isolated from solution is consistent with it being [Fe(py),(NcMe)][PF,],.…”

Thermochemical measurement of the ligand field splitting energies for hexaaquocopper(II) and hexaamminecopper(II)ions

“…Going back to the earlier paper (4) and substituting the present values in the figure showing the relative magnitudes of lODq for the complexes, the high values for that of hexaammine and hexaaquocopper(I1) ions are removed. Thus the present results lend more support to the validity of the thermochemical measurement of the ligand field splitting energy.…”

“…In the previous publications on the thermochemical measurement of the ligand field splitting energies of the hexaaquo and hexaammine complexes of some transition metal(I1) ions (1)(2)(3)(4)) the values for the complexes of copper(I1) ion were not included. By spectroscopic measurement, however, the 10Dq's for the hexaaquocopper(I1) and hexaamminecopper(I1) ions have been found to be 16 x lo3 cm-' and 12 x lo3 cm-' respectively (5,6).…”