Predictability for Polymeric Structure Deviations, Transition Temperature, and Transition Patterns in 1,2,4 H-Triazole Iron(II) Complexes Using Density Functional Theory Method

The computational study uses a hybrid functional and basis set TPSSh/TZVP to investigate structure changes, ST temperature, and ST pattern determination of the Fe(II)-Htrz complex in HS and LS states. The analysis used a Density Functional Theory Method and focused on the iron(II) 1,2,4 H -triazole complex polymer structure as facilitated via computational chemistry calculations with three molecular structure modeling. The outcome of our modeling shows that the distance between Fe(II) ions in the LS (low spin) state (3.67–3.71 Å) is shorter than in the HS (high spin) state (3.98–4.07 Å). Further, the Fe–N bond length in the LS state is 1.97–2.02 Å, and in the HS state it is 2.07–2.33 Å. Of note, dihedral angular data show that in the HS state, the 1,2,4 H -triazole iron(II) complex deviates from the linear-chain complex in LS states. ST temperature results from computational chemistry calculations on the second and third models are 342 and 348 K, respectively. The ST pattern resulting from a computational chemistry determination has a slow pattern. Application of the Density Functional Theory to a complex polymer structure has generated positive results that may lead to outcome predictability given changes in LS and HS states.