Spin State Crossover, Vibrational, Computational, and Structural Studies of Fe^II 1‐Isopropyl‐1H‐tetrazole Derivatives

Abstract

Mononuclear complexes of formula [Fe(iptz) 6 ]X 2 {X = BF 4 -(1), ClO 4 -(2); iptz = 1-isopropyl-1H-tetrazole} have been synthesized and characterized spectroscopically and structurally. These materials display a gradual and incomplete spin conversion around 95 K on cooling, as well as a reversible thermochromic effect. This magnetic behavior was satisfactorily simulated using the Sorai and Seki domain model (ΔH = 5.9 kJ mol

Thin Benzotriazole Films for Inhibition of Carbon Steel Corrosion in Neutral Electrolytes

“…The IR spectrum contains bands that can be attributed to the components of the azole layer bound to the surface. In fact, the bands near 640 cm −1 can be attributed to the vibrations of the triazole ring [19] and those near 1047 cm −1 to the vibrations of the triazole and benzene rings ( Figure 1) [29]. The bands at ca.…”

“…The bands at 1347 cm -1 , 1351 cm -1 , and 1380 cm -1 correspond to the vibrations of the -C-N bond in the triazole moiety [29], while the band at 1590 cm -1 corresponds to the -C=C vibrations of the benzene ring [24]. Moreover, the bands at about 1090, 1105, 1400, and 1415 cm -1 are attributed to complexes of azoles with Fe(II) [32], while the bands at 623, 1490, and 1500 cm -1 can be attributed to the vibrations of the Fe-N bonds ( Figure 2) [19]. To study the structure of the surface layer, an IR study of a steel surface modified with the BTA solution was carried out.…”

“…The bands at ca. 740-755 cm −1 , 885 cm −1 , and 1208 cm −1 correspond to the vibrations of the CH bond in the benzene ring [19,28,29]. The bands at 1096 cm −1 and 1201 cm −1 correspond to the vibrations of the N-H moiety of the triazole group [14,22], while those at 995 cm −1 and 1326 cm −1 correspond to the vibrations of the N-N bonds in the triazole ring [29][30][31].…”

“…BTA acts as a ligand in complexes with iron ions, becoming stable and sparingly soluble in water complexes (the log of stability constant of Fe (II) is 3.05 and of Fe (III) is 3.3 [12]). The stability of the complexes is the result of switching the spin state of a metal atom (the so-called "spin crossover") depending on external factors [18,19]. Moreover, elevated temperatures can cause a thermally induced transition between two electronic states in Fe (II) ions in these complex compounds: diamagnetic (S = 0, low-spin-LS) and paramagnetic (S = 2, high-spin-HS) [13].…”

Spatiotemporal Studies of the One‐Dimensional Coordination Polymer [Fe(ebtz)2(C2H5CN)2](BF4)2: Tug of War between the Nitrile Reorientation Versus Crystal Lattice as a Tool for Tuning the Spin Crossover Properties**

“…This might indicate whether there is a tendency for HS 2 to be stabilized with the above geometry owing to purely intramolecular interaction within the cation. We took the approach previously applied for the similar trans ‐Fe(N) 4 (NCS) 2 system [50a] . Namely, we first optimized the structures of the LS and HS isomers of the models of 1 – 5 , by using the mononuclear cationic models shown in Figure 9.…”