Study of thermodynamics and complex structures on spin transitions of [Fe2(Htrz)6(trz)3]Cl and [Fe4(Htrz)10(trz)5]Cl3 complexes using the Density Functional Theory method

Abstract

The complex of iron(II) 1,2,4 H-triazole chloride is a complex that has spin transition characteristics. Thermodynamic studies and determination of changes in complex structured data have been carried out on the [Fe2(Htrz)6(trz)3]Cl and [Fe4(Htrz)10(trz)5]Cl3 complexes with the DFT method. The iron(II) 1,2,4 H-triazole chloride complex has a polymeric structure, so in this study used a model with 2 and 4 Fe(II) ions. The computational chemistry study using a hybrid functional/basis set B3LYP/6-31G(d). The results obtained show the distance between the Fe(II) ions, the bond length of Fe-N, and the distance between the Fe(II) ions with Cl− in the [Fe2(Htrz)6(trz)3]Cl complex at low spin states respectively 3.717Å, 1.990Å-2.049Å, and 6.829Å, while in the high spin state respectively 3.932Å, 2.130Å-2.360Å and 7,050Å. The distance between the Fe(II) ions, the bond length of Fe-N, and the distance between the Fe(II) ions with Cl− in the [Fe4(Htrz)10(trz)5]Cl3 complex at low spin states respectively 3.661Å-3.681Å, 1.960Å-2.089Å and 5.037Å, while in the high spin state respectively 3.911Å-3.946Å, 2.092Å-2.367Å and 5.280Å. Thermodynamic data in [Fe2(Htrz)6(trz)3]Cl complex is ∆E=-24.38989kJ/Mol, ∆H=-24.3909kJ/Mol, ∆G=-47.9364kJ/Mol, and ∆S=0.0789kJ/Mol. Thermodynamic data of [Fe4(Htrz)10(trz)5]Cl3 complex is ∆E=-12.8564kJ/Mol, ∆H=-12.8564kJ/Mol, ∆G=-33.6445kJ/Mol, and ∆S=0.0697kJ/Mol. The structure and thermodynamic data are compatible with experimental measurement data in the laboratory.