Low-spin and spin-crossover iron(ii) complexes with pyridyl-benzimidazole ligands: synthesis, and structural, magnetic and solution study

Abstract

Two tridentate (L1=2,6-bis(1-(3,5-di-tert-butylbenzyl)-1H-benzimidazol-2-yl)pyridine and L2=2,6-bis(1-(4-tert-butylbenzyl)-1H-benzimidazol-2-yl)pyridine) and one didentate ligand (L3=1-(4-tert-butylbenzyl)-2-pyridine-2-yl-1H-benzimidazol) were used for the synthesis of eight mononuclear Fe(II) compounds 1-8 containing miscellaneous counterions. Single-crystal X-ray diffraction analysis confirmed the...

Guest-Induced Multistep-to-One-Step Reversible Spin Transition with Enhanced Hysteresis in a 2D Hofmann Framework

“…Furthermore, the energies of the 10Dq (difference between the average energy of the t 2g and e g set of orbitals) values (10Dq LS = 17472 cm −1 and 10Dq HS = 8676 cm −1 ) and the LF terms obtained from ab initio calculations are also in the range expected for Fe II complexes, as reported in the literature (Figure S23). 74 It was found that 1•1.3MeOH shows a HS LF term ( 5 Γ) as the ground state at 300 K with a 10Dq value of 6585 cm −1 , which is much lower than the optimized HS state (10Dq = 8676 cm −1 ) of the calculated fragment (Figure 7). This anomaly indicates that the HS states are more stabilized at 300 K in the solvated compound than the optimized HS structure.…”

Thermal- and light-induced SCO effect in Fe(II) complexes and coordination polymers

“…The family of homoleptic Fe(II) coordination compounds with bidentate 2-(2'-pyridyl)benzimidazole ligand (L2) and their derivatives often exhibit temperature-induced SCO effect (Brachňaková et al, 2020). Structural modification of L2 by introducing photoactive azophenyl moiety onto benzimidazole core (L3 = phenyl-(2-pyridine-2-yl-3Hbenzoimidazol-5-yl)-trans-diazene) offers an interesting possibility for LD-LISC investigation (Fig.…”

Spin state of two mononuclear iron(II) complexes of a tridentate bis(imino)pyridine N-donor ligand: Experimental and theoretical investigations

“…Yield: 0.23 g ( 46 %). 1 (3) Ligand L (0.15 g, 0.44 mmol) and Zn(BF 4 ) 2 ⋅6H 2 O (0.076 g, 0.22 mmol) were mixed in methanol (4 mL), the mixture was sonicated for 15 min and then stirred at room temperature for 30 min. The precipitated white solid was filtered, washed with diethyl ether and dried under vacuum, affording 3 in 72 % yield (0.146 g).…”

“…Spin states have a major role in defining the structure, reactivity, magnetic and spectroscopic properties of coordination compounds [1][2][3]. The change of spin state is accompanied primarily by a change in the electronic structure of the central metal ion, which varies the physical and chemical properties of the substances [4,5].…”

“…A clear discrimination with respect to spin state is observable in the case of transition metal complexes [6], due to the nature of d-orbitals of the metals which are close in energy and can be occupied in different ways depending on the metal oxidation state, its ligand field and coordination geometry [7][8][9]. Transition metal complexes in various coordination geometries (e.g., octahedral, square-pyramidal, trigonal-bipyramidal, tetrahedral) [10][11][12][13] show variable spin states and the switching between can be affected by external stimuli, such as temperature, light irradiation or pressure [3,[14][15][16]. Particularly, the spin states of mononuclear Fe(II) Schiff base complexes have been extensively studied in the view of both theory and applications [17][18][19].…”