Rapid cooling and magnetic field-induced cooperative effect for the metastable quintet state in a spin crossover complex

Yu, Zhi; Liu, K.; Jiang, Tao; Zhong, Zhuang Jin; You, Xiao‐Zeng; Siu, G. G.

doi:10.1063/1.123250

Cited by 23 publications

(19 citation statements)

References 20 publications

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“…From coordination compounds it is known that a certain quantity of the high-spin population can get trapped on rapid cooling, because the lattice does not have enough time to relax, a phenomenon known as "spin trapping". [32][33][34][35][36][37][38][39] Up to 6% of the high-spin population in [1,3- Figure S13. The data range is limited by a monochromator glitch at about 12.5 Å -1 that affects data at some temperatures more than others; the samples were very difficult to align because they were strongly tapered.…”

Section: Methodsmentioning

confidence: 99%

Supramolecular Catalysis of Orthoformate Hydrolysis in Basic Solution: An Enzyme-Like Mechanism

2008

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Abstract. Magnetic susceptibility measurements and X-ray data confirm that tert-butyl substituted manganocenes [(Me 3 C) n C 5 H 5-n ] 2 Mn (n= 1, 2) follow the trend previously observed with the methylated manganocenes, i.e., electron donating groups attached to the Cp ring stabilize the low-spin (LS) electronic ground state relative to Cp 2 Mn and exhibit higher spin-crossover (SCO) temperatures.However, introducing three CMe 3 groups on each ring gives a temperature invariant high-spin (HS) state manganocene. The origin of the high-spin state in [1,2,4-(Me 3 C) 3 C 5 H 2 ] 2 Mn is due to the significant bulk of the [1,2,4-(Me 3 C) 3 C 5 H 2 ] -ligand, which is sufficient to generate severe inter-ring steric strain that prevents the realization of the low-spin state. Interestingly, the spin transition in [1,3-(Me 3 C) 2 C 5 H 3 ] 2 Mn is accompanied by a phase transition resulting in a significant irreversible hysteresis (∆T c = 16 K). This structural transition was also observed by extended X-ray absorption fine-structure (EXAFS) measurements. Magnetic susceptibility studies and X-ray diffraction data on SiMe 3 substituted 2 manganocenes [(Me 3 Si) n C 5 H 5-n ] 2 Mn (n= 1, 2, 3) show high-spin configuration in these cases. Although tetra-and hexasubstituted manganocenes are high-spin at all accessible temperatures, the disubstituted manganocenes exhibit a small low-spin admixture at low temperature. In this respect it behaves similarily to [(Me 3 C)(Me 3 Si)C 5 H 3 ] 2 Mn, which has a constant low-spin admixture up to 90 K and then gradually converts to high-spin. Thermal spin-trapping can be observed for [(Me 3 C)(Me 3 Si)C 5 H 3 ] 2 Mn on rapid cooling.

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Section: Methodsmentioning

confidence: 99%

Supramolecular Catalysis of Orthoformate Hydrolysis in Basic Solution: An Enzyme-Like Mechanism

2008

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“…It has been demonstrated in the context of the study of large protein crystals that a flash cooled sample reaches the final temperature in a maximum of about 1 s [27]. On the contrary, a true flash cooling experiment is not possible in a squid cavity as, even though the latter is already at the required low temperature, the introduction of the fibre containing the sample inevitably induced a temperature gradient that only allow a rapid cooling experiment, the equilibrium can take a few minutes to achieve [18]. In general, such distinction should be taken in mind when comparing structural with magnetic squid experiment.…”

Section: Rapid Cooling and Flash Coolingmentioning

confidence: 97%

“…Futhermore, the X-ray diffraction crystal structure of a complex in a trapped metastable state has not been reported so far; despite it being suspected in most cases that the trapped HS ! LS relaxation is connected to the structural features [14,16,18].…”

Section: Introductionmentioning

confidence: 99%

Thermal trapped iron(II) high spin state investigated by X-ray diffraction

Marchivie

Guionneau

Létard

et al. 2004

Journal of Physics and Chemistry of Solids

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The possibilities to trap by flash cooling the high spin (HS) state of iron(II) in the [Fe(PM -BiA) 2 (NCS) 2 ] complex have been investigated by X-ray diffraction. This study reveals that trapping the HS state is possible under some conditions depending on the final temperature. If the latter is lower than the T(LIESST) temperature, the HS ! LS (low spin) relaxation is slow enough to determine the trapped HS crystal structure by X-ray diffraction. The crystal structure of this complex in the 30 K trapped HS state shows differences from either the room temperature (HS) or the 30 K (LS) crystal structures, as for example differences in the strength of the S· · ·H -C hydrogen bond like intermolecular interaction or the p-p interactions, known to play a crucial role in this compound for the propagation of the change in spin at the spin crossover (SCO), i.e. the cooperativity. The differences in intermolecular interactions are directly linked to the differences between the crystallographic unit cell modifications induced by pure thermal effects and those induced by the SCO. q

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“…The SCO complex [Fe(dpp) 2 (NCS) 2 ] Á py (dpp ¼ dipyrido[3,2-a:2 0 ,3 0 -c] phenazine, py ¼ pyridine] belongs to the family of the "classical" SCO complex [Fe(phen) 2 (NCS) 2 ] (phen ¼ 1,10-phenanthroline), but in contrast its spin transition behaviour shows an abrupt temperature dependence with a very wide thermal hysteresis (about 60 K) [10,11]. It is several hundred times larger than that of [Fe(phen) 2 (NCS) 2 ] [12].…”

Section: Introductionmentioning

confidence: 99%

“…It is several hundred times larger than that of [Fe(phen) 2 (NCS) 2 ] [12]. Ligands with extended aromatic rings are expected to show strong intermolecular p--p interactions [10,11,13] to enhance the cooperativity which is responsible for abruptness and thermal hysteresis in the spin transition behaviour [1,14,15].…”

Section: Introductionmentioning

confidence: 99%

Isostructural phase transition in the spin crossover compound [Fe(dpp)₂(NCS)₂] · py

Kusz¹,

Zubko

Fitch

et al. 2011

Zeitschrift für Kristallographie

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The spin crossover complex [Fe(dpp) 2 (NCS) 2 ] Á py crystallises in the monoclinic P2=n space group with one guest pyridine molecule per iron complex and undergoes an isostructural phase transition near 100 K on cooling and around 155 K on heating. The space group does not change upon spin transition despite the occurrence of hysteresis with ca. 55 K width, which is clearly seen in the temperature dependence of the lattice parameters. These are highly anisotropic upon spin transition, and surprisingly the unit cell volume reduces only little (0.1%) upon spin transition from high spin to low spin phase. The differences between the high-and low-spin structures are discussed.

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Rapid cooling and magnetic field-induced cooperative effect for the metastable quintet state in a spin crossover complex

Abstract: Rapid cooling and magnetic field-induced cooperative effect for the metastable quintet state in a spin crossover complex Permalink https://escholarship.org/uc/item/7fb4k5pr JournalApplied Physics Letters, 74(26)

Cited by 23 publications

References 20 publications

Supramolecular Catalysis of Orthoformate Hydrolysis in Basic Solution: An Enzyme-Like Mechanism

Supramolecular Catalysis of Orthoformate Hydrolysis in Basic Solution: An Enzyme-Like Mechanism

Thermal trapped iron(II) high spin state investigated by X-ray diffraction

Isostructural phase transition in the spin crossover compound [Fe(dpp)₂(NCS)₂] · py

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Rapid cooling and magnetic field-induced cooperative effect for the metastable quintet state in a spin crossover complex

Abstract: Rapid cooling and magnetic field-induced cooperative effect for the metastable quintet state in a spin crossover complex Permalink https://escholarship.org/uc/item/7fb4k5pr JournalApplied Physics Letters, 74(26)

Cited by 23 publications

References 20 publications

Supramolecular Catalysis of Orthoformate Hydrolysis in Basic Solution: An Enzyme-Like Mechanism

Supramolecular Catalysis of Orthoformate Hydrolysis in Basic Solution: An Enzyme-Like Mechanism

Thermal trapped iron(II) high spin state investigated by X-ray diffraction

Isostructural phase transition in the spin crossover compound [Fe(dpp)2(NCS)2] · py

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Isostructural phase transition in the spin crossover compound [Fe(dpp)₂(NCS)₂] · py