A Back‐to‐Back Ligand with Dipyrazolylpyridine and Dipicolylamine Metal‐Binding Domains

Tovee, Clare A.; Kilner, Colin A.; Barrett, Simon; Thomas, Jim A.; Halcrow, Malcolm A.

doi:10.1002/ejic.200901107

Cited by 24 publications

(13 citation statements)

References 85 publications

(53 reference statements)

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“…We therefore suggest the Fe N bond lengths in the high-spin state are the biggest contributor to 39 That gives a predicted T(latt) = 147 K, or T½(solid) = 68 K, from the correlation in Figure 4. SCO in [Fe(1-bpp)2] 2+ and [Fe(3-bpp)2] 2+ derivatives rarely extends below 100 K, [39][40][41] where they become kinetically trapped in their high spin states. 39,40,42 Correlations between T(latt) and  or  for group 3 in each spin state are all negative, and more scattered than the VOh plots.…”

Section: T½(solid)mentioning

confidence: 99%

Relationship between the Molecular Structure and Switching Temperature in a Library of Spin-Crossover Molecular Materials

et al. 2019

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Structure:function relationships are surveyed relating the spin-crossover (SCO) midpoint temperature (T½) in the solid state, for 43 members of the iron(II)/dipyrazolylpyridine family of SCO compounds. The difference between T½ in the solid state and in solution [T(latt)] is proposed as a measure of the lattice contribution to the transition temperature. Negative linear correlations between SCO temperature and the magnitude of the rearrangement of the coordination sphere during SCO are evident among isostructural or near-isostructural subsets of compounds; that is, a larger change in molecular structure during SCO stabilizes the high-spin state of a material. Improved correlations are often obtained when T(latt), rather than the raw T½ value, is considered as the measure of SCO temperature. Different lattice types show different tendencies to stabilize the high-spin or low-spin state of the molecules containing them, which correlates with the structural changes that most influence T(latt) in each case. These relationships are mostly unaffected by the SCO cooperativity in the compounds, or by the involvement of any crystallographic phase changes. One or two materials within each subset are outliers in some or all of these correlations however which, in some cases, can be attributed to small differences in their ligand geometry or unusual phase behavior during SCO. A reinvestigation of the structural chemistry of [Fe(3-bpp)2][NCS]2•nH2O (3-bpp = di{1H-pyrazol-3-yl}pyridine; n = 0 or 2), undertaken as part of this study, is also presented. .

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Section: T½(solid)mentioning

confidence: 99%

Relationship between the Molecular Structure and Switching Temperature in a Library of Spin-Crossover Molecular Materials

et al. 2019

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“…[2][3][4][5] If the coordination sites of ditopic ligands differ in their metal-chelating properties, discrimination by means of optimized synthetic protocols can yield hetero-metallic complexes. [6,7] The resulting complexes feature different catalytic, magnetic, and photophysical properties and may enable new cooperative functionality. [8][9][10][11][12] In this context, a number of bimetallic complex catalysts have been reported, e. g., in asymmetric allylic alkylation, [13] water oxidation, [14][15][16][17][18] epoxidation, [19] and transfer hydrogenation of ketones.…”

Section: Introductionmentioning

confidence: 99%

Ditopic Hexadentate Ligands with a Central Dihydrobenzo‐diimidazole Unit Forming a [2x2] Zn₄ Grid Complex

et al. 2021

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A family of ditopic hexadentate ligands based on the parent compound 2,6-bis(6-(pyrazol-1-yl)pyridin-2-yl)-1,5-dihydrobenzo [1,2-d:4,5-d']diimidazole (L) was developed and synthesized by using a straightforward condensation reaction, which forms the interlinking central benzo [1,2-d:4,5-d']diimidazole bridge in the ligand backbone. The two secondary amine groups of the benzodiimidazole unit tautomerize and allow the formation of two tauto-conformers, which upon treatment with metal salts forms different isomeric coordination complexes. Here we report six new derivatives (1-6) that can tautomerize (varying the pyrazolylpyridine part) and 14 derivatives (7-13) with different alkyl and benzyl substitution on secondary amino groups (of L) that prevent the tautomerization. This way, it is possible to study the properties of isomeric coordination complexes and their intrinsic cooperativity by the example of [2x2] grid complexes in the future. A [2x2] Zn 4 complex of the ligand L was synthesized and structurally characterized.

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“…[8][9][10] Thus bpp derivatives bearing fluorescent, [11][12][13] photoactive, [14,15] redox-active, [16] conducting, [17] magnetic, [18,19] amphiphilic [20,21] and tether group substituents [13,22,23] have all been prepared, as have ditopic bpp ligands. [10,12,15,19,21,24,25] Iron complexes of these novel ligands often exhibit useful and/or multifunctional SCO switching properties. The unique availability of so many materials based on the same [Fe(bpp) 2 ] 2 + core also facilitatess tructure-function studies of SCO switching.…”

Section: Introductionmentioning

confidence: 99%

Structural Transformations and Spin‐Crossover in [FeL₂]²⁺ Salts (L=4‐{tert‐Butylsulfanyl}‐2,6‐di{pyrazol‐1‐yl}pyridine): The Influence of Bulky Ligand Substituents

Kulmaczewski

Bamiduro

Shahid

et al. 2020

Chemistry A European J

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4‐(tert‐Butylsulfanyl)‐2,6‐di(pyrazol‐1‐yl)pyridine (L) was obtained in low yield from a one‐pot reaction of 2,4,6‐trifluoropyridine with 2‐methylpropane‐2‐thiolate and sodium pyrazolate in a 1:1:2 ratio. The materials [FeL2][BF4]2⋅solv (1[BF4]2⋅solv) and [FeL2][ClO4]2⋅solv (1[ClO4]2⋅solv; solv=MeNO2, MeCN or Me2CO) exhibit a variety of structures and spin‐state behaviors including thermal spin‐crossover (SCO). Solvent loss on heating 1[BF4]2⋅x MeNO2 (x≈2.3) occurs in two steps. The intermediate phase exhibits hysteretic SCO around 250 K, involving a “reverse‐SCO” step in its warming cycle at a scan rate of 5 K min−1. The reverse‐SCO is not observed in a slower 1 K min−1 measurement, however, confirming its kinetic nature. The final product [FeL2][BF4]2⋅0.75 MeNO2 was crystallographically characterized, and shows abrupt but incomplete SCO at 172 K which correlates with disorder of an L ligand. The asymmetric unit of 1[BF4]2⋅y Me2CO (y≈1.6) contains five unique complex molecules, four of which undergo gradual SCO in at least two discrete steps. Low‐spin 1[ClO4]2⋅0.5 Me2CO is not isostructural with its BF4− congener, and undergoes single‐crystal‐to‐single‐crystal solvent loss with a tripling of the crystallographic unit cell volume, while retaining the Ptrue1‾ space group. Three other solvate salts undergo gradual thermal SCO. Two of these are isomorphous at room temperature, but transform to different low‐temperature phases when the materials are fully low‐spin.

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A Back‐to‐Back Ligand with Dipyrazolylpyridine and Dipicolylamine Metal‐Binding Domains

Cited by 24 publications

References 85 publications

Relationship between the Molecular Structure and Switching Temperature in a Library of Spin-Crossover Molecular Materials

Relationship between the Molecular Structure and Switching Temperature in a Library of Spin-Crossover Molecular Materials

Ditopic Hexadentate Ligands with a Central Dihydrobenzo‐diimidazole Unit Forming a [2x2] Zn₄ Grid Complex

Structural Transformations and Spin‐Crossover in [FeL₂]²⁺ Salts (L=4‐{tert‐Butylsulfanyl}‐2,6‐di{pyrazol‐1‐yl}pyridine): The Influence of Bulky Ligand Substituents

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A Back‐to‐Back Ligand with Dipyrazolylpyridine and Dipicolylamine Metal‐Binding Domains

Cited by 24 publications

References 85 publications

Relationship between the Molecular Structure and Switching Temperature in a Library of Spin-Crossover Molecular Materials

Relationship between the Molecular Structure and Switching Temperature in a Library of Spin-Crossover Molecular Materials

Ditopic Hexadentate Ligands with a Central Dihydrobenzo‐diimidazole Unit Forming a [2x2] Zn4 Grid Complex

Structural Transformations and Spin‐Crossover in [FeL2]2+ Salts (L=4‐{tert‐Butylsulfanyl}‐2,6‐di{pyrazol‐1‐yl}pyridine): The Influence of Bulky Ligand Substituents

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Ditopic Hexadentate Ligands with a Central Dihydrobenzo‐diimidazole Unit Forming a [2x2] Zn₄ Grid Complex

Structural Transformations and Spin‐Crossover in [FeL₂]²⁺ Salts (L=4‐{tert‐Butylsulfanyl}‐2,6‐di{pyrazol‐1‐yl}pyridine): The Influence of Bulky Ligand Substituents