Anion driven modulation of magnetic intermolecular interactions and spin crossover properties in an isomorphous series of mononuclear iron(iii) complexes with a hexadentate Schiff base ligand

CrystEngComm ◽  
2012 ◽  
Vol 14 (20) ◽  
pp. 7015 ◽  
Author(s):  
Ivan Nemec ◽  
Radovan Herchel ◽  
Ivan Šalitroš ◽  
Zdeněk Trávníček ◽  
Ján Moncoľ ◽  
...  
Keyword(s):  
Schiff Base ◽  
Intermolecular Interactions ◽  
Schiff Base Ligand ◽  
Spin Crossover ◽  
Mononuclear Iron

scholarly journals Iron(II) Spin Crossover Complex with the 1,2,3-Triazole-Containing Linear Pentadentate Schiff-Base Ligand and the MeCN Monodentate Ligand

Crystals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 276 ◽  
Author(s):  
Tomoe Matsuyama ◽  
Keishi Nakata ◽  
Hiroaki Hagiwara ◽  
Taro Udagawa
Keyword(s):  
Schiff Base ◽  
Schiff Base Ligand ◽  
Spin Crossover ◽  
Variable Temperature ◽  
Spin Transition ◽  
Ligand Field ◽  
X Ray Diffraction ◽  
Monodentate Ligand ◽  
X Ray ◽  
Mononuclear Iron

A mononuclear iron(II) complex bearing the linear pentadentate N5 Schiff-base ligand containing two 1,2,3-triazole moieties and the MeCN monodentate ligand, [FeIIMeCN(L3-Me-3Ph)](BPh4)2·MeCN·H2O (1), have been prepared (L3-Me-3Ph = bis(N,N′-1-Phenyl-1H-1,2,3-triazol-4-yl-methylideneaminopropyl)methylamine). Variable-temperature magnetic susceptibility measurements revealed an incomplete one-step spin crossover (SCO) from the room-temperature low-spin (LS, S = 0) state to a mixture of the LS and high-spin (HS, S = 2) species at the higher temperature of around 400 K upon first heating, which is irreversible on the consecutive cooling mode. The magnetic modulation at around 400 K was induced by the crystal-to-amorphous transformation accompanied by the loss of lattice MeCN solvent, which was evident from powder X-ray diffraction (PXRD) studies and themogravimetry. The single-crystal X-ray diffraction studies showed that the complex is in the LS state (S = 0) between 296 and 387 K. In the crystal lattice, the complex-cations and B(1)Ph4− ions are alternately connected by intermolecular CH···π interactions between the methyl group of the MeCN ligand and phenyl groups of B(1)Ph4− ions, forming a 1D chain structure. The 1D chains are further connected by P4AE (parallel fourfold aryl embrace) interactions between two neighboring complex-cations, constructing a 2D extended structure. B(2)Ph4− ions and MeCN lattice solvents exist in the spaces of the 2D layer. DFT calculations verified that the 1,2,3-triazole-containing ligand L3-Me-3Ph gives a stronger ligand field around the octahedral coordination environment of the iron(II) ion than the analogous imidazole-containing ligand H2L2Me (= bis(N,N′-2-methylimidazol-4-yl-methylideneaminopropyl)methylamine) of the known compound [FeIIMeCN(H2L2Me)](BPh4)1.5·Cl0.5·0.5MeCN (2) reported by Matsumoto et al. (Nishi, K.; Fujinami, T.; Kitabayashi, A.; Matsumoto, N. Tetrameric spin crossover iron(II) complex constructed by imidazole⋯chloride hydrogen bonds. Inorg. Chem. Commun. 2011, 14, 1073–1076), resulting in the much higher spin transition temperature of 1 than that of 2.

Spin-crossover in an iron(iii) complex showing a broad thermal hysteresis

2021 ◽  
Author(s):  
Cyril Rajnák ◽  
Romana Mičová ◽  
Ján Moncoľ ◽  
Ľubor Dlháň ◽  
Christoph Krüger ◽  
...  
Keyword(s):  
Schiff Base ◽  
Schiff Base Ligand ◽  
Spin Crossover ◽  
Thermal Hysteresis ◽  
Mononuclear Complex ◽  
Hysteresis Width ◽  
Thermally Induced

A pentadentate Schiff-base ligand 3,5Cl-L2− and NCSe− form a iron(iii) mononuclear complex [Fe(3,5Cl-L)(NCSe)], which shows a thermally induced spin crossover with a broad hysteresis width of 24 K between 123 K (warming) and 99 K (cooling).

scholarly journals Structural Evidence of Spin State Selection and Spin Crossover Behavior of Tripodal Schiff Base Complexes of tris(2-aminoethyl)amine and Related Tripodal Amines

2020 ◽  
Vol 6 (2) ◽  
pp. 28
Author(s):  
Greg Brewer
Keyword(s):  
Schiff Base ◽  
Spin State ◽  
Density Functional ◽  
Spin Crossover ◽  
Bimodal Distribution ◽  
Structural Features ◽  
Schiff Base Complexes ◽  
Mononuclear Iron ◽  
Experimental Values ◽  
State Selection

A review of the tripodal Schiff base (SB) complexes of tris(2-aminoethyl)amine, Nap(CH2CH 2NH2)3 (tren), and a few closely related tripodal amines with Cr(II), Mn(III) (d4), Mn(II), Fe(III) (d5), Fe(II) (d6), and Co(II) (d7) is provided. Attention is focused on examination of key structural features, the M-Nimine, M-Namine, or M-O and M-Nap bond distances and Nimine-M-N(O) bite and C-Nap-C angles and how these values correlate with spin state selection and spin crossover (SCO) behavior. A comparison of these experimental values with density functional theory calculated values is also given. The greatest number, 132, of complexes is observed with cationic mononuclear iron(II) in a N6 donor set, Fe(II)N6. The dominance of two spin states, high spin (HS) and low spin (LS), in these systems is indicated by the bimodal distribution of histogram plots of Fe(II)-Nimine and Fe(II)-Nazole/pyridine bond distances and of Nimine–Fe(II)-Nazole/pyridine and C-Nap-C bond angles. The values of the two maxima, corresponding to LS and HS states, in each of these histograms agree closely with the theoretical values. The iron(II)-Nimine and iron(II)-Nazole/pyridine bond distances correlate well for these complexes. Examples of SCO complexes of this type are tabulated and a few of the 20 examples are discussed that exhibit interesting features. There are only a few mononuclear iron(III) cationic complexes and one is SCO. In addition, a significant number of supramolecular complexes of these ligands that exhibit SCO, intervalence, and chiral recognition are discussed. A summary is made regarding the current state of this area of research and possible new avenues to explore based on analysis of the present data.

scholarly journals Impact of Substituent Variation on the Presence of Thermal Spin Crossover in a Series of Mononuclear Iron(III) Schiff Base Complexes with Terminal Pseudohalido Co-ligands

2017 ◽  
Vol 24 (20) ◽  
pp. 5191-5203 ◽  
Author(s):  
Lukáš Pogány ◽  
Barbora Brachňaková ◽  
Ján Moncol ◽  
Ján Pavlik ◽  
Ivan Nemec ◽  
...  
Keyword(s):  
Schiff Base ◽  
Spin Crossover ◽  
Schiff Base Complexes ◽  
Mononuclear Iron

scholarly journals 4,4′,6,6′-Tetrabromo-2,2′-[(E,E)-ethane-1,2-diylbis(nitrilomethanylylidene)]diphenol

2012 ◽  
Vol 68 (8) ◽  
pp. o2348-o2348 ◽  
Author(s):  
Hadi Kargar ◽  
Reza Kia ◽  
Amir Adabi Ardakani ◽  
Muhammad Nawaz Tahir
Keyword(s):  
Schiff Base ◽  
Hydrogen Bonds ◽  
Intermolecular Interactions ◽  
Schiff Base Ligand ◽  
Title Compound ◽  
Inversion Center ◽  
Asymmetric Unit ◽  
Tetradentate Schiff Base ◽  
Compound C

The asymmetric unit of the title compound, C16H12Br4N2O2, comprises half of a potential tetradentate Schiff base ligand. The whole molecule is generated by an inversion center located in the middle of the C—C bond of the ethylene segment. There are intramolecular O—H...N hydrogen bonds makingS(6) ring motifs. In the crystal, no significant intermolecular interactions are observed.

Steric Trapping of the High Spin State in FeIII Quinolylsalicylaldimine Complexes

2014 ◽  
Vol 67 (11) ◽  
pp. 1574 ◽  
Author(s):  
Darunee Sertphon ◽  
David J. Harding ◽  
Phimphaka Harding ◽  
Keith S. Murray ◽  
Boujemaa Moubaraki ◽  
...  
Keyword(s):  
Schiff Base ◽  
Electronic Properties ◽  
High Spin ◽  
Spin State ◽  
Schiff Base Ligand ◽  
Room Temperature ◽  
Spin Crossover ◽  
High Spin State ◽  
Electrochemical Studies ◽  
Magnetic Studies

A new sterically bulky Schiff base ligand, N-(8-quinolyl)-5-tert-butylsalicylaldimine (Hqsal-5-tBu) has been prepared and a series of FeIII complexes, [Fe(qsal-5-tBu)2]Y (Y = Cl 1, ClO4 2, NO3 3, BF4 4) utilising this ligand are reported and fully characterised. UV-vis spectroscopic and electrochemical studies indicate that 1–4 are high spin (HS) in solution at room temperature and further suggest that the tBu group only slightly alters the electronic properties of 1–4 compared with related [Fe(qsal-5-X)2]+ systems. The structures of [Fe(qsal-5-tBu)2]Cl·4MeOH·H2O 1, [Fe(qsal-5-tBu)2]ClO4·MeOH 2, and [Fe(qsal-5-tBu)2]NO3 3 determined at 100 K reveal HS FeIII centres in all cases. Four-fold parallel aryl embraces and π–π interactions serve to link the cations forming 2D sheets mirroring the motifs found in other [Fe(qsal-5-X)2]+ complexes. Despite this the tBu group causes strong distortions at the Fe centre which as magnetic studies reveal prevent spin crossover trapping 1–4 in the HS state.

scholarly journals Spin Crossover in Three Mononuclear Iron (III) Schiff Base Complexes

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 849 ◽  
Author(s):  
Ivan Nemec ◽  
Ingrid Svoboda ◽  
Radovan Herchel
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Schiff Base ◽  
Spin Crossover ◽  
Theoretical Calculations ◽  
Magnetic Behavior ◽  
Schiff Base Complexes ◽  
Mononuclear Iron ◽  
Mononuclear Complexes

The synthesis, crystal structure, and magnetic properties of three new mononuclear complexes [Fe(R-LA)(L1)](BPh4), where R-LA2− is a doubly deprotonated pentadentate Schiff base ligand and L1 is a monodentate benzimidazole or furopyridine ligand, are reported. Ligand- and anion-driven changes in crystal structures and magnetic behavior were investigated in terms of the magnetic susceptibility measurements and theoretical calculations.

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