Unconventional Spin Crossover in Dinuclear and Trinuclear Iron(III) Complexes with Cyanido and Metallacyanido Bridges

Šalitroš, Ivan; Boča, Roman; Dlháň, Ľubor; Gembický, Milan; Kožı́šek, Jozef; Linarès, Jorge; Moncóľ, Ján; Němec, Ivan; Perašínová, Lucia; Renz, Franz; Svoboda, Ingrid; Fueß, H.

doi:10.1002/ejic.200900169

Cited by 30 publications

(7 citation statements)

References 26 publications

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“…15,18,19 The chromophore bond lengths are listed in 1), which correspond well with the values found for the purely LS cyanido complexes reported previously. 15,19,20 The crystal structures of 1a-1g are very similar. They are composed of the [Fe(L 5 )(NCX)] and Solv molecules which form a three-dimensional framework via C-H⋯O and C-H⋯π weak interactions.…”

Section: General Description Of Molecular and Crystal Structuresmentioning

confidence: 89%

The relationship between the strength of hydrogen bonding and spin crossover behaviour in a series of iron(iii) Schiff base complexes

2015

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X-ray crystal structures and magnetic properties of an isostructural series of iron(III) Schiff base complexes with the general formula [Fe(L(5))(NCX)]·Solv (where H2L(5) = N,N'-bis(2-hydroxy-naphthylidene)-1,6-diamino-4-azahexane, X = S, Solv = tetrahydrofuran, 1a; X = S, Solv = methanol and 0.5 pyrazine, 1b; X = S, Solv = butanone, 1c; Solv = N,N'-dimethylformamide, X = S (1d) or X = Se (1d'); X = S, Solv = dimethyl sulfoxide, 1e) are reported. In the crystals, the individual [Fe(L(5))(NCX)] molecules are connected through weak C-H···O, C-H···π or C-H···S non-covalent contacts into 2D supramolecular networks, while the guest-solvent (Solv) molecules are trapped in the cavities between two adjacent layers, which are furthermore stabilized by N-H···O hydrogen bonds connecting the Solv oxygen atom with the amine group of the [Fe(L(5))(NCX)] molecule, with the N···O distances varying from 2.921(6) Å (in 1d') to 3.295(2) Å (in 1a). The magnetic properties of the complexes were tuned by the different Solv molecules and as a result of this, four new spin crossover (SCO) compounds with cooperative spin transitions are reported, which are accompanied by thermal hysteresis in two cases (1d and 1e): , T1/2 = 84 K; 1d, T1/2↓ = 232 K, T1/2↑ = 235 K and 1e, T1/2↓ = 127 K, T1/2↑ = 138 K. The role of the N-H···O hydrogen bonding in the occurrence and tuning of SCO was also computationally studied using a topological analysis, and also by evaluation of non-covalent interaction (NCI) indexes. Both theoretical approaches showed a clear relationship between the strength of the N-H···O hydrogen bonds and T1/2, as already inferred from X-ray structural and magnetic data.

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Section: General Description Of Molecular and Crystal Structuresmentioning

confidence: 89%

The relationship between the strength of hydrogen bonding and spin crossover behaviour in a series of iron(iii) Schiff base complexes

2015

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“…Multinuclear SCO complexes have been investigated intensively within the last 15 years, exhibiting promising SCO behaviours for possible applications, in particular binuclear complexes. [57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72][73][74][75][76] Compared to spin state switching in mononuclear compounds, multinuclear complexes promise more drastic changes of the macroscopic material properties. For instance, the total amount of unpaired electrons -and therefore the magnetic moment -as well as their coupling could accumulate over all metallic centres, increasing interactions compared to those in mononuclear complexes (e.g.…”

Section: 56mentioning

confidence: 99%

“…Fe III -d 5 in HS: S = 5/2; dinuclear Fe III -d 5 in HS: S = 10/2; up to S = 60/2 in a dodecanuclear complex). 64,77 In addition, some intermediate states can be populated, leading to various switching processes and intramolecular interactions between metal centres. For instance, dinuclear Fe II complexes assumed the existence of spin pairs being in either a [LS-LS] state at lower temperatures or a [HS-HS] state at higher temperatures, leading to sequential switching or direct spin transitions.…”

Section: Concerted or Sequential Switching In Multinuclear Spin Cross...mentioning

confidence: 99%

Spin state switching of metal complexes by visible light or hard X-rays

et al. 2016

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Electromagnetic stimuli of spin crossover compounds restricted to UV-vis light irradiation for many years could be recently extended to X-ray excitation. This review covers a large variety of light-induced effects, as well as recent analogues stimulated by X-ray irradiation which have not yet been reviewed. The focus is also on multistable multinuclear spin crossover compounds which are the subject of lively discussions within the spin crossover community. Their spin transition often occurs incompletely and with different switching mechanisms. In this review, we recall a predicted sequential switching induced thermally as well as a concerted stimulation mechanism by light irradiation for these interesting multifunctional materials.

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“…Octahedral metal complexes with pentadentate ligand are of interest since their ligand field strength can be systematically controlled by modifying the additional monodentate ligand in line with the spectrochemical series [30][31][32], and such a characteristic is useful not only for exhibiting SCO but also for the possible tuning of T 1/2 . These complexes are also beneficial for the construction of polynuclear materials such as di [33][34][35][36][37][38][39][40][41][42], tri [43], tetra [44], penta [45], hepta [46][47][48], nona [48] and dodecanuclear [49] complexes by using bridging ligands instead of monodentate ligands for exhibiting multi-step spin transition. In the pentadentate ligand system, although iron(III) SCO compounds are well known [50][51][52][53][54][55][56][57], iron(II) spin transition systems are quite rare [58,59].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2019

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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.

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Unconventional Spin Crossover in Dinuclear and Trinuclear Iron(III) Complexes with Cyanido and Metallacyanido Bridges

Abstract: A nonsymmetrical triamine, 1,6-diamino-4-azahexane, was Schiff-condensed with (X-substituted)

Cited by 30 publications

References 26 publications

The relationship between the strength of hydrogen bonding and spin crossover behaviour in a series of iron(iii) Schiff base complexes

The relationship between the strength of hydrogen bonding and spin crossover behaviour in a series of iron(iii) Schiff base complexes

Spin state switching of metal complexes by visible light or hard X-rays

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

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