Transition metal nitroprussides: Crystal and electronic structure, and related properties

Reguera, L.; Ávila, Y.; Reguera, E.

doi:10.1016/j.ccr.2020.213764

Cited by 44 publications

(102 citation statements)

References 210 publications

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“…In 3D transition metal nitroprussides, the axial CN group forms a weaker coordination bond with the metal linked at the N end of the CN ligand, than the one formed by the equatorial CN ligands. [26] This makes possible the rupture of the metal-NC axial bond during the sonication of the solid suspension, induced by the affinity of the organic molecule to form a coordination bond with the metal, which results in the obtaining of a hybrid inorganic-organic solid where the organic molecule is finally found occupying the axial coordination sites for the metal at the layer. [29][30][31] When the suspension is aged in the darkness, for two or three days, a fine precipitate is obtained, which is separated from the mother liquor (by centrifugation) and then washed several times with distilled water until obtaining a filtrate free of accompanying ions.…”

Section: Methodsmentioning

confidence: 99%

“…This explains that the formed solid has an anhydrous character, unlike the parent 3D phase, which contains coordinated water molecules. [26] Its long-range order (crystallinity) increases on aging within the mother liquid. After three days of resting, its XRD powder pattern has enough quality to be indexed in the monoclinic unit cell reported for the iron analog [23] but in the P2 1 space group.…”

Section: No] Solid Solutionsmentioning

confidence: 99%

“…These two series of solid solutions were found to form isostructural (monoclinic, P2 1 space group) phases, similar to the reported for their 3D analogs, Fe 1-x T x [Fe(CN) 5 NO] • nH 2 O, which crystallize into a cubic unit cell (Fm-3m). [24,25,26] The effect of the iron dilution on the thermally-induced SCO behavior has been documented for other polynuclear cyanide-based solids, [27] but the results of such studies cannot be extrapolated to ferrous nitroprussides by two reasons, i) the presence of CN Axial À NO interactions in the interlayer region; ii) the relatively low electron density at CN5σ molecular orbital for the equatorial CN ligands related to the bonding properties of the nitrosyl group. The formation of solid solutions for the Fe 1-x T x (Pyz)[Fe(CN) 5 NO] hybrid solids was verified from XRD, IR, Raman, and Mössbauer data.…”

Section: Introductionmentioning

confidence: 99%

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Thermally‐Induced Spin‐Crossover in Fe_1‐xT_x(pyrazine)[Fe(CN)₅NO] with T=Co, Ni – Effects of Iron Atom Dilution

et al. 2021

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2D ferrous nitroprusside with the pyrazine molecule as a pillar between adjacent layers shows a thermally induced spincrossover behavior. This supposes that the energy gap between the high and low spin states is the order of kT in the temperature region where such a spin transition is observed. If a fraction of the iron atoms involved in that transition is progressively replaced by a second metal, to form a solid solution (alloy), the thermal effect could be modified due to the iron atom dilution, but such behavior also depends on the bonding properties of the ligands for the iron atom and of the NO and CN interaction in the interlayer region. This hypothesis was the idea that motivated the preparation of the titled systems of solid solutions and their study from magnetic and Mössbauer data recorded at different temperatures in the range of 5-300 K, complemented with XRD, Raman, and IR measurements. Co and Ni were considered to form the solid solutions under study because they form isostructural solids in the parent 3D coordination polymers. For both metals, the formed solids show a spin-crossover effect for all the compositions range but from a certain degree of dilution for the iron atom, above 75 % substitution by the second metal, the thermal hysteresis almost disappears. This suggests that from that dilution degree, the spin transition involves structural changes at the local coordination environment for the iron atom but not for the entire solid framework. This hypothesis is properly supported by the recorded Raman and Mössbauer spectra. The presence of Co and Ni atoms in the solid solutions results in higher stability for the entropy-driven high spin state. This is appreciated as lower values for T# HS , 1/2 , and T" LS , 1/2 corresponding to the temperatures where the subscript 1/2 indicates the temperature where 50 % of the metal centers have changed their spin state.

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Section: Methodsmentioning

confidence: 99%

Section: No] Solid Solutionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermally‐Induced Spin‐Crossover in Fe_1‐xT_x(pyrazine)[Fe(CN)₅NO] with T=Co, Ni – Effects of Iron Atom Dilution

et al. 2021

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“…The HS → LS spin transition on the sample cooling is perceptible through a change in its color, from grey at room temperature (300 K), to violet at 77 K. For a complete spin transition, purple color is expected for the material at low temperature (77 K) corresponding to the metal-ligand-charge transfer in the nitroprusside ion, with a strong absorption band at 498 nm due to the 2b 2 (xy) →7e(π*NO) (Fe→NO) electronic transition [1].…”

Section: C) Thermally-induced Spin Transitionmentioning

confidence: 99%

“…In the high spin (HS) state the sample color has two contributions, the light absorption by the metal d-d transitions and the one originated by the metal-ligand charge transfer (MLCT). For a complete HS →LS transition, the rst contribution disappears, and the sample suffers a pronounced color change, which could be purple if the MLCT absorbs light below 500 nm; this is the case of the nitroprusside ion, for instance [1]. These changes in the sample color are easily detected by simple visual inspection of the sample or recording the corresponding UV-vis-NIR spectra.…”

Section: Introductionmentioning

confidence: 99%

Fe[4-(3-Phenylpropyl)pyridine]2[Fe(CN)5NO]: A 2D coordination polymer with thermally-induced spin transition and nature of its asymmetric hysteresis loop

Scanda¹,

Avila²,

Mojica³

et al. 2022

Preprint

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The titled material crystallizes with an orthorhombic unit cell, in the P21212 space group (Nr. 18). Its crystal structure was solved and refined from XRD powder patterns. The solid framework is formed by stacked undulated sheets of inorganic nature, Fe[Fe(CN)5NO], separated by bimolecular organic pillars, [4-(3-Phenylpropyl)pyridine]2, which remain coordinated to the axial coordination sites for the iron atom and occupy the interlayer region. The molecules forming these pillars remain coupled through C-H⋅⋅⋅π and dispersive interactions between neighboring molecules. When this solid is cooled and then warming, a reversible spin transition, from high to low spin (HS → LS), and vice versa, is observed. This transition occurs in the temperature interval of 135–165 K, with a hysteresis between them of about 20 K. That hysteresis loop appears with a pronounced asymmetry when the slopes for the HS → LS and LS → HS transitions are compared. This effect is discussed in terms of the related structural changes in the solid structure during the spin transitions. The transition was also monitored from IR and Raman spectra recorded at 80 and 300 K. Relevant information on the electronic structure for both, the LS and HS phases of this material, was derived from the corresponding XPS spectra recorded at 114 and 270 K. This contribution emphasizes the role of the nitrosyl group (NO) as an electron buffer for tuning the bonding properties of the inorganic layer at the CN 5σ orbital to make possible the observed thermally-induced SCO behavior.

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Old Materials for New Functions: Recent Progress on Metal Cyanide Based Porous Materials

2021

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Cyanide is the simplest ligand with strong basicity to construct open frameworks including some of the oldest compounds reported in the history of coordination chemistry. Cyanide can form numerous cyanometallates with different transition metal ions showing diverse geometries. Rational design of robust extended networks is enabled by the strong bonding nature and high directionality of cyanide ligand. By virtue of a combination of cyanometallates and/or organic linkers, multifunctional framework materials can be targeted and readily synthesized for various applications, ranging from molecular adsorptions/separations to energy conversion and storage, and spin-crossover materials. External guest-and stimuli-responsive behaviors in cyanide-based materials are also highlighted for the development of the next-generation smart materials. In this review, an overview of the recent progress of cyanide-based multifunctional materials is presented to demonstrate the great potential of cyanide ligands in the development of modern coordination chemistry and material science.

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Transition metal nitroprussides: Crystal and electronic structure, and related properties

Cited by 44 publications

References 210 publications

Thermally‐Induced Spin‐Crossover in Fe_1‐xT_x(pyrazine)[Fe(CN)₅NO] with T=Co, Ni – Effects of Iron Atom Dilution

Thermally‐Induced Spin‐Crossover in Fe_1‐xT_x(pyrazine)[Fe(CN)₅NO] with T=Co, Ni – Effects of Iron Atom Dilution

Fe[4-(3-Phenylpropyl)pyridine]2[Fe(CN)5NO]: A 2D coordination polymer with thermally-induced spin transition and nature of its asymmetric hysteresis loop

Old Materials for New Functions: Recent Progress on Metal Cyanide Based Porous Materials

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Transition metal nitroprussides: Crystal and electronic structure, and related properties

Cited by 44 publications

References 210 publications

Thermally‐Induced Spin‐Crossover in Fe1‐xTx(pyrazine)[Fe(CN)5NO] with T=Co, Ni – Effects of Iron Atom Dilution

Thermally‐Induced Spin‐Crossover in Fe1‐xTx(pyrazine)[Fe(CN)5NO] with T=Co, Ni – Effects of Iron Atom Dilution

Fe[4-(3-Phenylpropyl)pyridine]2[Fe(CN)5NO]: A 2D coordination polymer with thermally-induced spin transition and nature of its asymmetric hysteresis loop

Old Materials for New Functions: Recent Progress on Metal Cyanide Based Porous Materials

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Product

Resources

About

Thermally‐Induced Spin‐Crossover in Fe_1‐xT_x(pyrazine)[Fe(CN)₅NO] with T=Co, Ni – Effects of Iron Atom Dilution

Thermally‐Induced Spin‐Crossover in Fe_1‐xT_x(pyrazine)[Fe(CN)₅NO] with T=Co, Ni – Effects of Iron Atom Dilution