1
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Kulmaczewski R, Halcrow MA. Iron(II) complexes of 2,6-bis(imidazo[1,2- a]pyridin-2-yl)pyridine and related ligands with annelated distal heterocyclic donors. Dalton Trans 2023; 52:14928-14940. [PMID: 37799008 DOI: 10.1039/d3dt02747c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/07/2023]
Abstract
Following a published synthesis of 2,6-bis(imidazo[1,2-a]pyridin-2-yl)pyridine (L1), treatment of α,α'-dibromo-2,6-diacetylpyridine with 2 equiv. 2-aminopyrimidine or 2-aminoquinoline in refluxing acetonitrile respectively gives 2,6-bis(imidazo[1,2-a]pyrimidin-2-yl)pyridine (L2) and 2,6-bis(imidazo[1,2-a]quinolin-2-yl)pyridine (L3). Solvated crystals of [Fe(L1)2][BF4]2 (1[BF4]2) and [Fe(L2)2][BF4]2 (2[BF4]2) are mostly high-spin, although one solvate of 1[BF4]2 undergoes thermal spin-crossover on cooling. The iron coordination geometry is consistently distorted in crystals of 2[BF4]2 which may reflect the influence of intramolecular, inter-ligand N⋯π interactions on the molecular conformation. Only 1 : 1 Fe : L3 complexes were observed in solution, or isolated in the solid state; a crystal structure of [FeBr(py)2L3]Br·0.5H2O (py = pyridine) is presented. A solvate crystal structure of high-spin [Fe(L4)2][BF4]2 (L4 = 2,6-di{quinolin-2-yl}pyridine; 4[BF4]2) is also described, which exhibits a highly distorted six-coordinate geometry with a helical ligand conformation. The iron(II) complexes are high-spin in solution at room temperature, but 1[BF4]2 and 2[BF4]2 undergo thermal spin-crossover equilibria on cooling. All the compounds exhibit a ligand-based emission in solution at room temperature. Gas phase DFT calculations mostly reproduce the spin state properties of the complexes, but show small anomalies attributed to intramolecular, inter-ligand dispersion interactions in the sterically crowded molecules.
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Affiliation(s)
- Rafal Kulmaczewski
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, UK LS2 9JT.
| | - Malcolm A Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, UK LS2 9JT.
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2
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Smith RA, Kulmaczewski R, Halcrow MA. Ligand-Directed Metalation of a Gold Pyrazolate Cluster. Inorg Chem 2023. [PMID: 37285352 DOI: 10.1021/acs.inorgchem.3c01667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Solid "[AuL]" (HL = 3-[pyrid-2-yl]-5-tertbutyl-1H-pyrazole) can be crystallized as cyclic [Au3(μ-L)3] and [Au4(μ-L)4] clusters from different solvents. The crystalline tetramer contains a square Au4 core with an HT:TH:TH:HT arrangement of ligand substituents, which preorganizes the cluster to chelate to additional metal ions via its pendant pyridyl groups. The addition of 0.5 equiv of AgBF4 to [AuL] yields [Ag2Au4(μ3-L)4][BF4]2, where two edges of the Au4 square are spanned by Ag+ ions via metallophilic Ag···Au contacts. Treatment of [AuL] with [Cu(NCMe)4]PF6 affords the metalloligand helicate [Cu2Au2(μ-L)4][PF6]2, via oxidation of the copper and partial fragmentation of the cluster.
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Affiliation(s)
- Ryan A Smith
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, United Kingdom
| | - Rafal Kulmaczewski
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, United Kingdom
| | - Malcolm A Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, United Kingdom
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3
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Kulmaczewski R, Armstrong IT, Catchpole P, Ratcliffe ESJ, Vasili HB, Warriner SL, Cespedes O, Halcrow MA. Di-Iron(II) [2+2] Helicates of Bis-(Dipyrazolylpyridine) Ligands: The Influence of the Ligand Linker Group on Spin State Properties. Chemistry 2023; 29:e202202578. [PMID: 36382594 PMCID: PMC10108139 DOI: 10.1002/chem.202202578] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 11/15/2022] [Accepted: 11/16/2022] [Indexed: 11/18/2022]
Abstract
Four bis[2-{pyrazol-1-yl}-6-{pyrazol-3-yl}pyridine] ligands have been synthesized, with butane-1,4-diyl (L1 ), pyrid-2,6-diyl (L2 ), benzene-1,2-dimethylenyl (L3 ) and propane-1,3-diyl (L4 ) linkers between the tridentate metal-binding domains. L1 and L2 form [Fe2 (μ-L)2 ]X4 (X- =BF4 - or ClO4 - ) helicate complexes when treated with the appropriate iron(II) precursor. Solvate crystals of [Fe2 (μ-L1 )2 ][BF4 ]4 exhibit three different helicate conformations, which differ in the torsions of their butanediyl linker groups. The solvates exhibit gradual thermal spin-crossover, with examples of stepwise switching and partial spin-crossover to a low-temperature mixed-spin form. Salts of [Fe2 (μ-L2 )2 ]4+ are high-spin, which reflects their highly twisted iron coordination geometry. The composition and dynamics of assembly structures formed by iron(II) with L1 -L3 vary with the ligand linker group, by mass spectrometry and 1 H NMR spectroscopy. Gas-phase DFT calculations imply the butanediyl linker conformation in [Fe2 (μ-L1 )2 ]4+ influences its spin state properties, but show anomalies attributed to intramolecular electrostatic repulsion between the iron atoms.
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Affiliation(s)
- Rafal Kulmaczewski
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Isaac T Armstrong
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Pip Catchpole
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK.,Department of Chemistry, Lancaster University, Lancaster, LA1 4YB, UK
| | - Emily S J Ratcliffe
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Hari Babu Vasili
- School of Physics and Astronomy W. H. Bragg Building, University of Leeds, Leeds, LS2 9JT, UK
| | - Stuart L Warriner
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Oscar Cespedes
- School of Physics and Astronomy W. H. Bragg Building, University of Leeds, Leeds, LS2 9JT, UK
| | - Malcolm A Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
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4
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Kulmaczewski R, Kershaw Cook LJ, Pask CM, Cespedes O, Halcrow MA. Iron(II) Complexes of 4-(Alkyldisulfanyl)-2,6-di(pyrazolyl)pyridine Derivatives. Correlation of Spin-Crossover Cooperativity with Molecular Structure Following Single-Crystal-to-Single-Crystal Desolvation. Cryst Growth Des 2022; 22:1960-1971. [PMID: 35431660 PMCID: PMC9007408 DOI: 10.1021/acs.cgd.2c00005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 01/24/2022] [Indexed: 06/14/2023]
Abstract
The complex salts [Fe(L 1)2]X2 (1X 2 ; L 1 = 4-(isopropyldisulfanyl)-2,6-bis(pyrazolyl)pyridine; X- = BF4 -, ClO4 -) form solvated crystals from common organic solvents. Crystals of 1X 2 ·Me2CO show abrupt spin transitions near 160 K, with up to 22 K thermal hysteresis. 1X 2 ·Me2CO cocrystallizes with other, less cooperative acetone solvates, which all transform into the same solvent-free materials 1X 2 ·sf upon exposure to air, or mild heating. Conversion of 1X 2 ·Me2CO to 1X 2 ·sf proceeds in a single-crystal to single-crystal fashion. 1X 2 ·sf are not isomorphous with the acetone solvates, and exhibit abrupt spin transitions at low temperature with hysteresis loops of 30-38 K (X- = BF4 -) and 10-20 K (X- = ClO4 -), depending on the measurement method. Interestingly, the desolvation has an opposite effect on the SCO temperature and hysteresis in the two salts. The hysteretic spin transitions in 1X 2 ·Me2CO and 1X 2 ·sf do not involve a crystallographic phase change but are accompanied by a significant rearrangement of the metal coordination sphere. Other solvates 1X 2 ·MeNO2, 1X 2 ·MeCN, and 1X 2 ·H2O are mostly isomorphous with each other and show more gradual spin-crossover equilibria near room temperature. All three of these lattice types have similar unit cell dimensions and contain cations associated into chains through pairwise, intermolecular S···π interactions. Polycrystalline [Fe(L 2)2][BF4]2·MeNO2 (2[BF 4 ] 2 ·MeNO2; L 2 = 4-(methyldisulfanyl)-2,6-bis(pyrazolyl)pyridine) shows an abrupt spin transition just above room temperature, with an unsymmetrical and structured hysteresis loop, whose main features are reversible upon repeated thermal scanning.
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Affiliation(s)
- Rafal Kulmaczewski
- School
of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K.
| | | | - Christopher M. Pask
- School
of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K.
| | - Oscar Cespedes
- School
of Physics and Astronomy, University of
Leeds, E. C. Stoner
Building, Leeds LS2 9JT, U.K.
| | - Malcolm A. Halcrow
- School
of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K.
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5
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Capel Berdiell I, Davies DJ, Woodworth J, Kulmaczewski R, Cespedes O, Halcrow MA. Structures and Spin States of Iron(II) Complexes of Isomeric 2,6-Di(1,2,3-triazolyl)pyridine Ligands. Inorg Chem 2021; 60:14988-15000. [PMID: 34547208 DOI: 10.1021/acs.inorgchem.1c02404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Iron(II) complex salts of 2,6-di(1,2,3-triazol-1-yl)pyridine (L1) are unexpectedly unstable in undried solvent. This is explained by the isolation of [Fe(L1)4(H2O)2][ClO4]2 and [Fe(NCS)2(L1)2(H2O)2]·L1, containing L1 bound as a monodentate ligand rather than in the expected tridentate fashion. These complexes associate into 44 grid structures through O-H···N hydrogen bonding; a solvate of a related 44 coordination framework, catena-[Cu(μ-L1)2(H2O)2][BF4]2, is also presented. The isomeric ligands 2,6-di(1,2,3-triazol-2-yl)pyridine (L2) and 2,6-di(1H-1,2,3-triazol-4-yl)pyridine (L3) bind to iron(II) in a more typical tridentate fashion. Solvates of [Fe(L3)2][ClO4]2 are low-spin and diamagnetic in the solid state and in solution, while [Fe(L2)2][ClO4]2 and [Co(L3)2][BF4]2 are fully high-spin. Treatment of L3 with methyl iodide affords 2,6-di(2-methyl-1,2,3-triazol-4-yl)pyridine (L4) and 2-(1-methyl-1,2,3-triazol-4-yl)-6-(2-methyl-1,2,3-triazol-4-yl)pyridine (L5). While salts of [Fe(L5)2]2+ are low-spin in the solid state, [Fe(L4)2][ClO4]2·H2O is high-spin, and [Fe(L4)2][ClO4]2·3MeNO2 exhibits a hysteretic spin transition to 50% completeness at T1/2 = 128 K (ΔT1/2 = 6 K). This transition proceeds via a symmetry-breaking phase transition to an unusual low-temperature phase containing three unique cation sites with high-spin, low-spin, and 1:1 mixed-spin populations. The unusual distribution of the spin states in the low-temperature phase reflects "spin-state frustration" of the mixed-spin cation site by an equal number of high-spin and low-spin nearest neighbors. Gas-phase density functional theory calculations reproduce the spin-state preferences of these and some related complexes. These highlight the interplay between the σ-basicity and π-acidity of the heterocyclic donors in this ligand type, which have opposing influences on the molecular ligand field. The Brønsted basicities of L1-L3 are very sensitive to the linkage isomerism of their triazolyl donors, which explains why their iron complex spin states show more variation than the better-known iron(II)/2,6-dipyrazolylpyridine system.
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Affiliation(s)
- Izar Capel Berdiell
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Daniel J Davies
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Jack Woodworth
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Rafal Kulmaczewski
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Oscar Cespedes
- School of Physics and Astronomy, University of Leeds, E. C. Stoner Building, Leeds LS2 9JT, U.K
| | - Malcolm A Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
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6
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Galadzhun I, Kulmaczewski R, Cespedes O, Halcrow MA. Iron/2,6‐Di(pyrazol‐1‐yl)pyridine Complexes with a Discotic Pattern of Alkyl or Alkynyl Substituents. Eur J Inorg Chem 2021. [DOI: 10.1002/ejic.202100435] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Iurii Galadzhun
- School of Chemistry University of Leeds Woodhouse Lane Leeds LS2 9JT UK
| | | | - Oscar Cespedes
- School of Physics and Astronomy University of Leeds EC Stoner Building Leeds LS2 9JT UK
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7
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Berdiell IC, Kulmaczewski R, Shahid N, Cespedes O, Halcrow MA. The number and shape of lattice solvent molecules controls spin-crossover in an isomorphous series of crystalline solvate salts. Chem Commun (Camb) 2021; 57:6566-6569. [PMID: 34113938 DOI: 10.1039/d1cc02624k] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Crystals of [FeL2][BF4]2·nMeCN (L = N-(2,6-di{pyrazol-1-yl}pyrid-4-yl)acetamide; n = 1 or 2) and [FeL2][ClO4]2·MeCN are isomorphous. When n = 1 the compounds exhibit an abrupt, hysteretic spin-transition below 200 K, but when n = 2 the material remains high-spin on cooling. [FeL2]X2·EtCN (X- = BF4- or ClO4-) are isomorphous with the MeCN solvates and undergo their spin-transition at almost the same temperature. However this now occurs in two-steps via a re-entrant mixed-spin intermediate phase, which correlates with crystallographic ordering of the bent propionitrile molecule.
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Affiliation(s)
- Izar Capel Berdiell
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK. and Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, P.O. Box 1527, Heraklion GR-711 10, Greece
| | - Rafal Kulmaczewski
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK.
| | - Namrah Shahid
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK.
| | - Oscar Cespedes
- School of Physics and Astronomy, University of Leeds, EC Stoner Building, Leeds LS2 9JT, UK
| | - Malcolm A Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK.
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8
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Kulmaczewski R, Howard MJ, Halcrow MA. Influence of ligand substituent conformation on the spin state of an iron(II)/di(pyrazol-1-yl)pyridine complex. Dalton Trans 2021; 50:3464-3467. [PMID: 33660725 DOI: 10.1039/d1dt00590a] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The temperature of the solution-phase spin-crossover equilibrium in iron(ii) complexes of 4-alkylsulfanyl-2,6-di{pyrazol-1-yl}pyridine (bppSR) complexes depends strongly on the alkylsulfanyl substituent. DFT calculations imply this reflects the conformation of the alkylsulfanyl groups, which lie perpendicular to the heterocyclic ligand donors in [Fe(bppStBu)2]2+ but are oriented co-planar with the ligand core for smaller SR substituents.
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Affiliation(s)
- Rafal Kulmaczewski
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, UK LS2 9JT.
| | - Mark J Howard
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, UK LS2 9JT.
| | - Malcolm A Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, UK LS2 9JT.
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9
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Kulmaczewski R, Bamiduro F, Shahid N, Cespedes O, Halcrow MA. Structural Transformations and Spin-Crossover in [FeL 2 ] 2+ Salts (L=4-{tert-Butylsulfanyl}-2,6-di{pyrazol-1-yl}pyridine): The Influence of Bulky Ligand Substituents. Chemistry 2021; 27:2082-2092. [PMID: 33073890 DOI: 10.1002/chem.202004072] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 10/16/2020] [Indexed: 11/06/2022]
Abstract
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 Me2 CO) 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 Me2 CO (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 Me2 CO 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 P 1 ‾ 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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Affiliation(s)
- Rafal Kulmaczewski
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Faith Bamiduro
- School of Chemical and Process Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Namrah Shahid
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Oscar Cespedes
- School of Physics and Astronomy, University of Leeds, E. C. Stoner Building, Leeds, LS2 9JT, UK
| | - Malcolm A Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
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10
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Galadzhun I, Kulmaczewski R, Shahid N, Cespedes O, Howard MJ, Halcrow MA. The flexibility of long chain substituents influences spin-crossover in isomorphous lipid bilayer crystals. Chem Commun (Camb) 2021; 57:4039-4042. [DOI: 10.1039/d1cc01073e] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
These two compounds are isomorphous but show different spin-state behaviour on cooling. This may be influenced by the packing of alkyl vs. alkynyl chains in the solid state.
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Affiliation(s)
| | | | - Namrah Shahid
- School of Chemistry
- University of Leeds
- Woodhouse Lane
- Leeds
- UK
| | - Oscar Cespedes
- School of Physics and Astronomy
- University of Leeds
- Leeds LS2 9JT
- UK
| | - Mark J. Howard
- School of Chemistry
- University of Leeds
- Woodhouse Lane
- Leeds
- UK
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11
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Capel Berdiell I, Kulmaczewski R, Warriner SL, Cespedes O, Halcrow MA. Front Cover: Iron and Silver Complexes of 4‐(Imidazol‐1‐yl)‐2,6‐di(pyrazol‐1‐yl)‐pyridine (
L
), Including a [Fe
3
(µ‐F)
2
F
6
L
8
]
+
Assembly (Eur. J. Inorg. Chem. 46/2020). Eur J Inorg Chem 2020. [DOI: 10.1002/ejic.202000992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
| | | | | | - Oscar Cespedes
- School of Physics and Astronomy University of Leeds EC Stoner Building LS2 9JT Leeds UK
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12
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Capel Berdiell I, Kulmaczewski R, Warriner SL, Cespedes O, Halcrow MA. Iron and Silver Complexes of 4‐(Imidazol‐1‐yl)‐2,6‐di(pyrazol‐1‐yl)‐pyridine (
L
), Including a [Fe
3
(µ‐F)
2
F
6
L
8
]
+
Assembly. Eur J Inorg Chem 2020. [DOI: 10.1002/ejic.202000782] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
| | | | | | - Oscar Cespedes
- School of Physics and Astronomy University of Leeds EC Stoner Building LS2 9JT Leeds UK
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13
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Greatorex S, Fokin SV, Kulmaczewski R, Yamada M, Cespedes O, Yoshinari N, Konno T, Sproules S, Ovcharenko VI, Halcrow MA. Modulating the Magnetic Properties of Copper(II)/Nitroxyl Heterospin Complexes by Suppression of the Jahn–Teller Distortion. Inorg Chem 2020; 59:8657-8662. [DOI: 10.1021/acs.inorgchem.0c01345] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sam Greatorex
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Sergey V. Fokin
- International Tomography Center, Siberian Branch of Russian Academy of Science, Institutskaya Strasse 3a, Novosibirsk 630090, Russia
| | - Rafal Kulmaczewski
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Mihoko Yamada
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
- Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Oscar Cespedes
- School of Physics and Astronomy, University of Leeds, EC Stoner Building, Leeds LS2 9JT, U.K
| | - Nobuto Yoshinari
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Takumi Konno
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Stephen Sproules
- WestCHEM, School of Chemistry, University of Glasgow, Glasgow G12 8QQ, U.K
| | - Victor I. Ovcharenko
- International Tomography Center, Siberian Branch of Russian Academy of Science, Institutskaya Strasse 3a, Novosibirsk 630090, Russia
| | - Malcolm A. Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
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14
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Pask CM, Greatorex S, Kulmaczewski R, Baldansuren A, McInnes EJL, Bamiduro F, Yamada M, Yoshinari N, Konno T, Halcrow MA. Elucidating the Structural Chemistry of a Hysteretic Iron(II) Spin-Crossover Compound From its Copper(II) and Zinc(II) Congeners. Chemistry 2020; 26:4833-4841. [PMID: 32017244 DOI: 10.1002/chem.202000101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Indexed: 11/12/2022]
Abstract
Annealing [FeL2 ][BF4 ]2 ⋅2 H2 O (L=2,6-bis-[5-methyl-1H-pyrazol-3-yl]pyridine) affords an anhydrous material, which undergoes a spin transition at T1/2 =205 K with a 65 K thermal hysteresis loop. This occurs through a sequence of phase changes, which were monitored by powder diffraction in an earlier study. [CuL2 ][BF4 ]2 ⋅2 H2 O and [ZnL2 ][BF4 ]2 ⋅2 H2 O are not perfectly isostructural but, unlike the iron compound, they undergo single-crystal-to-single-crystal dehydration upon annealing. All the annealed compounds initially adopt the same tetragonal phase but undergo a phase change near room temperature upon re-cooling. The low-temperature phase of [CuL2 ][BF4 ]2 involves ordering of its Jahn-Teller distortion, to a monoclinic lattice with three unique cation sites. The zinc compound adopts a different, triclinic low-temperature phase with significant twisting of its coordination sphere, which unexpectedly becomes more pronounced as the crystal is cooled. Synchrotron powder diffraction data confirm that the structural changes in the anhydrous zinc complex are reproduced in the high-spin iron compound, before the onset of spin-crossover. This will contribute to the wide hysteresis in the spin transition of the iron complex. EPR spectra of copper-doped [Fe0.97 Cu0.03 L2 ][BF4 ]2 imply its low-spin phase contains two distinct cation environments in a 2:1 ratio.
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Affiliation(s)
- Christopher M Pask
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Sam Greatorex
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Rafal Kulmaczewski
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Amgalanbaatar Baldansuren
- School of Chemistry and Photon Science Institute, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.,current address: Chemistry and Chemical Biology, 120 Cogswell, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, NY, 12180, USA
| | - Eric J L McInnes
- School of Chemistry and Photon Science Institute, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Faith Bamiduro
- School of Chemical and Process Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Mihoko Yamada
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan.,current address: Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan
| | - Nobuto Yoshinari
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan
| | - Takumi Konno
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan
| | - Malcolm A Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK.,Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan
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15
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Capel Berdiell I, Farmiloe SE, Kulmaczewski R, Halcrow MA. Molecular squares, coordination polymers and mononuclear complexes supported by 2,4-dipyrazolyl-6H-1,3,5-triazine and 4,6-dipyrazolylpyrimidine ligands. Dalton Trans 2019; 48:17310-17320. [PMID: 31720621 DOI: 10.1039/c9dt04003j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The Fe[BF4]2 complex of 2,4-di(pyrazol-1-yl)-6H-1,3,5-triazine (L1) is a high-spin molecular square, [{Fe(L1)}4(μ-L1)4][BF4]8, whose crystals also contain the unusual HPzBF3 (HPz = pyrazole) adduct. Three other 2,4-di(pyrazol-1-yl)-6H-1,3,5-triazine derivatives with different pyrazole substituents (L2-L4) are unstable in the presence of first row transition ions, but form mononuclear, polymeric or molecular square complexes with silver(i). Most of these compounds involve bis-bidentate di(pyrazolyl)triazine coordination, which is unusual for that class of ligand, and the molecular squares encapsulate one or two BF4-, ClO4- or SbF6- ions through combinations of anionπ, AgX and/or C-HX (X = O or F) interactions. Treatment of Fe[NCS]2 or Fe[NCSe]2 with 4,6-di(pyrazol-1-yl)-2H-pyrimidine (L5) or its 2-methyl and 2-amino derivatives (L6 and L7) yields mononuclear [Fe(NCE)2L2] and/or the 1D coordination polymers catena-[Fe(NCE)2(μ-L)] (E = S or Se, L = L5-L7). Alcohol solvates of isomorphous [Fe(NCS)2L2] and [Fe(NCSe)2L2] compounds show different patterns of intermolecular hydrogen bonding, reflecting the acceptor properties of the anion ligands. These iron compounds are all high-spin, although annealing solvated crystals of [Fe(NCSe)2(L5)2] affords a new phase exhibiting an abrupt, low-temperature spin transition. Catena-[Fe(H2O)2(μ-L5)][ClO4]2 is a coordination polymer of alternating cis and trans iron centres.
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Affiliation(s)
- Izar Capel Berdiell
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK.
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16
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Berdiell IC, Hochdörffer T, Desplanches C, Kulmaczewski R, Shahid N, Wolny JA, Warriner SL, Cespedes O, Schünemann V, Chastanet G, Halcrow MA. Supramolecular Iron Metallocubanes Exhibiting Site-Selective Thermal and Light-Induced Spin-Crossover. J Am Chem Soc 2019; 141:18759-18770. [DOI: 10.1021/jacs.9b08862] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Izar Capel Berdiell
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Tim Hochdörffer
- Department of Physics, Technical University of Kaiserslautern, Erwin Schrödinger Straße 46, D-67663 Kaiserslautern, Germany
| | | | - Rafal Kulmaczewski
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Namrah Shahid
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Juliusz A. Wolny
- Department of Physics, Technical University of Kaiserslautern, Erwin Schrödinger Straße 46, D-67663 Kaiserslautern, Germany
| | - Stuart L. Warriner
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Oscar Cespedes
- School of Physics and Astronomy, EC Stoner Building, University of Leeds, Leeds LS2 9JT, U.K
| | - Volker Schünemann
- Department of Physics, Technical University of Kaiserslautern, Erwin Schrödinger Straße 46, D-67663 Kaiserslautern, Germany
| | | | - Malcolm A. Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
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17
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Halcrow MA, Capel Berdiell I, Pask CM, Kulmaczewski R. Relationship between the Molecular Structure and Switching Temperature in a Library of Spin-Crossover Molecular Materials. Inorg Chem 2019; 58:9811-9821. [PMID: 31335133 DOI: 10.1021/acs.inorgchem.9b00843] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Structure-function relationships relating the spin-crossover (SCO) midpoint temperature (T1/2) in the solid state are surveyed for 43 members of the iron(II) dipyrazolylpyridine family of SCO compounds. The difference between T1/2 in the solid state and in solution [ΔT(latt)] is proposed as a measure of the lattice contribution to the transition temperature. Negative linear correlations between the 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 the molecular structure during SCO stabilizes the high-spin state of a material. Improved correlations are often obtained when ΔT(latt), rather than the raw T1/2 value, is considered as the measure of the SCO temperature. Different lattice types show different tendencies to stabilize the high-spin or low-spin state of the molecules they contain, which correlates with the structural changes that most influence ΔT(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 = bis(1H-pyrazol-3-yl)pyridine; n = 0 or 2], undertaken as part of this study, is also presented.
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Affiliation(s)
- Malcolm A Halcrow
- School of Chemistry , University of Leeds , Woodhouse Lane , Leeds LS2 9JT , U.K
| | - Izar Capel Berdiell
- School of Chemistry , University of Leeds , Woodhouse Lane , Leeds LS2 9JT , U.K
| | - Christopher M Pask
- School of Chemistry , University of Leeds , Woodhouse Lane , Leeds LS2 9JT , U.K
| | - Rafal Kulmaczewski
- School of Chemistry , University of Leeds , Woodhouse Lane , Leeds LS2 9JT , U.K
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18
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Vallone SP, Tantillo AN, Dos Santos AM, Molaison JJ, Kulmaczewski R, Chapoy A, Ahmadi P, Halcrow MA, Sandeman KG. Giant Barocaloric Effect at the Spin Crossover Transition of a Molecular Crystal. Adv Mater 2019; 31:e1807334. [PMID: 30985035 DOI: 10.1002/adma.201807334] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 02/22/2019] [Indexed: 06/09/2023]
Abstract
The first experimental evidence for a giant, conventional barocaloric effect (BCE) associated with a pressure-driven spin crossover transition near room temperature is provided. Magnetometry, neutron scattering, and calorimetry are used to explore the pressure dependence of the SCO phase transition in polycrystalline samples of protonated and partially deuterated [FeL2 ][BF4 ]2 [L = 2,6-di(pyrazol-1-yl)pyridine] at applied pressures of up to 120 MPa (1200 bar). The data indicate that, for a pressure change of only 0-300 bar (0-30 MPa), an adiabatic temperature change of 3 K is observed at 262 K or 257 K in the protonated and deuterated materials, respectively. This BCE is equivalent to the magnetocaloric effect (MCE) observed in gadolinium in a magnetic field change of 0-1 Tesla. The work confirms recent predictions that giant, conventional BCEs will be found in a wide range of SCO compounds.
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Affiliation(s)
- Steven P Vallone
- Department of Physics, Brooklyn College, CUNY, 2900 Bedford Avenue, Brooklyn, NY, 11210, USA
- Physics Program, The Graduate Center, CUNY, 365 Fifth Avenue, New York, NY, 10016, USA
| | - Anthony N Tantillo
- Department of Physics, Brooklyn College, CUNY, 2900 Bedford Avenue, Brooklyn, NY, 11210, USA
- Physics Program, The Graduate Center, CUNY, 365 Fifth Avenue, New York, NY, 10016, USA
| | - António M Dos Santos
- Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6393, USA
| | - Jamie J Molaison
- Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6393, USA
| | - Rafal Kulmaczewski
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Antonin Chapoy
- Hydrates, Flow Assurance & Phase Equilibria Research Group, Institute of Petroleum Engineering, Heriot-Watt University, EH14 4AS, Edinburgh, UK
| | - Pezhman Ahmadi
- Hydrates, Flow Assurance & Phase Equilibria Research Group, Institute of Petroleum Engineering, Heriot-Watt University, EH14 4AS, Edinburgh, UK
| | - Malcolm A Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Karl G Sandeman
- Department of Physics, Brooklyn College, CUNY, 2900 Bedford Avenue, Brooklyn, NY, 11210, USA
- Physics Program, The Graduate Center, CUNY, 365 Fifth Avenue, New York, NY, 10016, USA
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19
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Galadzhun I, Kulmaczewski R, Cespedes O, Yamada M, Yoshinari N, Konno T, Halcrow MA. 2,6-Bis(pyrazol-1-yl)pyridine-4-carboxylate Esters with Alkyl Chain Substituents and Their Iron(II) Complexes. Inorg Chem 2018; 57:13761-13771. [DOI: 10.1021/acs.inorgchem.8b02289] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Iurii Galadzhun
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Rafal Kulmaczewski
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Oscar Cespedes
- School of Physics and Astronomy, University of Leeds, E. C. Stoner Building, Leeds LS2 9JT, U.K
| | - Mihoko Yamada
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Nobuto Yoshinari
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Takumi Konno
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Malcolm A. Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
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20
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Burrows KE, Kulmaczewski R, Cespedes O, Barrett SA, Halcrow MA. The speciation of homochiral and heterochiral diastereomers of homoleptic cobalt(II) and zinc(II) PyBox complexes. Polyhedron 2018. [DOI: 10.1016/j.poly.2018.04.030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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21
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Capel Berdiell I, Kulmaczewski R, Cespedes O, Halcrow MA. An Incomplete Spin Transition Associated with a Z'=1→Z'=24 Crystallographic Symmetry Breaking. Chemistry 2018; 24:5055-5059. [PMID: 29111607 PMCID: PMC5972820 DOI: 10.1002/chem.201704896] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Indexed: 12/31/2022]
Abstract
Crystalline [FeL2 ][BF4 ]2 ⋅Me2 CO (L=N-[2,6-di{pyrazol-1-yl}pyrid-4-yl]acetamide) is high-spin at room temperature, and undergoes an abrupt, hysteretic spin-crossover at T1/2 =137 K (ΔT1/2 =14 K) that proceeds to about 50 % completeness. This is associated with a crystallographic phase transition, from phase 1 (P21 /c, Z=4) to phase 2 (P21 , Z=48). The cations associate into chains in the crystal through weak intermolecular π⋅⋅⋅π interactions. Phase 2 contains a mixture of high-spin and low-spin molecules, which are grouped into triads along these chains. The perchlorate salt [FeL2 ][ClO4 ]2 ⋅Me2 CO also adopts phase 1 at room temperature but undergoes a different phase transition near 135 K to phase 3 (P21 /c, Z=8) without a change in spin state.
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Affiliation(s)
- Izar Capel Berdiell
- School of ChemistryUniversity of LeedsWoodhouse LaneLeedsLS2 9JTUnited Kingdom
| | - Rafal Kulmaczewski
- School of ChemistryUniversity of LeedsWoodhouse LaneLeedsLS2 9JTUnited Kingdom
| | - Oscar Cespedes
- School of Physics and AstronomyUniversity of LeedsE.C. Stoner BuildingLeedsLS2 9JTUnited Kingdom
| | - Malcolm A. Halcrow
- School of ChemistryUniversity of LeedsWoodhouse LaneLeedsLS2 9JTUnited Kingdom
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22
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Capel Berdiell I, Kulmaczewski R, Cespedes O, Halcrow MA. Frontispiece: An Incomplete Spin Transition Associated with a Z
′=1→ Z
′=24 Crystallographic Symmetry Breaking. Chemistry 2018. [DOI: 10.1002/chem.201882065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Izar Capel Berdiell
- School of Chemistry; University of Leeds; Woodhouse Lane Leeds LS2 9JT United Kingdom
| | - Rafal Kulmaczewski
- School of Chemistry; University of Leeds; Woodhouse Lane Leeds LS2 9JT United Kingdom
| | - Oscar Cespedes
- School of Physics and Astronomy; University of Leeds; E.C. Stoner Building Leeds LS2 9JT United Kingdom
| | - Malcolm A. Halcrow
- School of Chemistry; University of Leeds; Woodhouse Lane Leeds LS2 9JT United Kingdom
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Capel Berdiell I, Kulmaczewski R, Halcrow MA. Iron(II) Complexes of 2,4-Dipyrazolyl-1,3,5-triazine Derivatives-The Influence of Ligand Geometry on Metal Ion Spin State. Inorg Chem 2017; 56:8817-8828. [PMID: 28699741 DOI: 10.1021/acs.inorgchem.7b00699] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Seven [FeL2][BF4]2 complex salts were prepared, where L is a 6-substituted 2,4-di(pyrazol-1-yl)-1,3,5-triazine (bpt) derivative. The complexes are all crystallographically high-spin, and exhibit significant distortions from an ideal D2d-symmetric coordination geometry. In one case, an unusual type of metal ion disorder was observed among a cubic array of ligands in the crystal lattice. The complexes are also high-spin between 3 and 300 K in the solid state and, where measured, between 239 and 333 K in CD3CN solution. This result is unexpected, since homoleptic iron(II) complexes of related 2,6-di(pyrazol-1-yl)pyridine, 2,6-di(pyrazol-1-yl)pyrazine, and 2,6-di(pyrazol-1-yl)pyrimidine derivatives often exhibit thermal spin-crossover behavior. Gas-phase density functional theory calculations confirm the high-spin form of [Fe(bpt)2]2+ and its derivatives is stabilized relative to iron(II) complexes of the other ligand types. This reflects a weaker Fe/pyrazolyl σ-bonding interaction, which we attribute to a small narrowing of the chelate ligand bite angle associated with the geometry of the 1,3,5-triazinyl ring. Hence, the high-spin state of [Fe(bpt)2]2+ centers does not reflect the electronic properties of its heterocyclic ligand donors but is imposed by the bpt ligand conformation. A high-spin homoleptic iron(III) complex of one of the bpt derivatives was also synthesized.
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Affiliation(s)
- Izar Capel Berdiell
- School of Chemistry, University of Leeds , Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Rafal Kulmaczewski
- School of Chemistry, University of Leeds , Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Malcolm A Halcrow
- School of Chemistry, University of Leeds , Woodhouse Lane, Leeds LS2 9JT, U.K
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Burrows KE, McGrath SE, Kulmaczewski R, Cespedes O, Barrett SA, Halcrow MA. Spin States of Homochiral and Heterochiral Isomers of [Fe(PyBox) 2 ] 2+ Derivatives. Chemistry 2017; 23:9067-9075. [PMID: 28387453 DOI: 10.1002/chem.201700820] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Indexed: 11/08/2022]
Abstract
The following iron(II) complexes of 2,6-bis(oxazolinyl)pyridine (PyBox; LH ) derivatives are reported: [Fe(LH )2 ][ClO4 ]2 (1); [Fe((R)-LMe )2 ][ClO4 ]2 ((R)-2; LMe =2,6-bis{4-methyloxazolinyl}pyridine); [Fe((R)-LPh )2 ][ClO4 ]2 ((R)-3) and [Fe((R)-LPh )((S)-LPh )][ClO4 ]2 ((RS)-3; LPh =2,6-bis{4-phenyloxazolinyl}pyridine); and [Fe((R)-LiPr )2 ][ClO4 ]2 ((R)-4) and [Fe((R)-LiPr )((S)-LiPr )][ClO4 ]2 ((RS)-4; LiPr =2,6-bis{4-isopropyloxazolinyl}pyridine). Solid (R)-3⋅MeNO2 exhibits an unusual very gradual, but discontinuous thermal spin-crossover with an approximate T1/2 of 350 K. The discontinuity around 240 K lies well below T1/2 , and is unconnected to a crystallographic phase change occurring at 170 K. Rather, it can be correlated with a gradual ordering of the ligand conformation as the temperature is raised. The other solid compounds either exhibit spin-crossover above room temperature (1 and (RS)-3), or remain high-spin between 5-300 K [(R)-2, (R)-4 and (RS)-4]. Homochiral (R)-3 and (R)-4 exhibit more twisted ligand conformations and coordination geometries than their heterochiral isomers, which can be attributed to steric clashes between ligand substituents [(R)-3]; or, between the isopropyl substituents of one ligand and the backbone of the other ((R)-4). In solution, (RS)-3 retains its structural integrity but (RS)-4 undergoes significant racemization through ligand redistribution by 1 H NMR. (R)-4 and (RS)-4 remain high-spin in solution, whereas the other compounds all undergo spin-crossover equilibria. Importantly, T1/2 for (R)-3 (244 K) is 34 K lower than for (RS)-3 (278 K) in CD3 CN, which is the first demonstration of chiral discrimination between metal ion spin states in a molecular complex.
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Affiliation(s)
- Kay E Burrows
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Sarah E McGrath
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Rafal Kulmaczewski
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Oscar Cespedes
- School of Physics and Astronomy, University of Leeds, E. C. Stoner Building, Leeds, LS2 9JT, UK
| | - Simon A Barrett
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - Malcolm A Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
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Burrows KE, McGrath SE, Kulmaczewski R, Cespedes O, Barrett SA, Halcrow MA. Inside Cover: Spin States of Homochiral and Heterochiral Isomers of [Fe(PyBox) 2
] 2+
Derivatives (Chem. Eur. J. 38/2017). Chemistry 2017. [DOI: 10.1002/chem.201701746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Kay E. Burrows
- School of Chemistry; University of Leeds; Woodhouse Lane Leeds LS2 9JT UK
| | - Sarah E. McGrath
- School of Chemistry; University of Leeds; Woodhouse Lane Leeds LS2 9JT UK
| | - Rafal Kulmaczewski
- School of Chemistry; University of Leeds; Woodhouse Lane Leeds LS2 9JT UK
| | - Oscar Cespedes
- School of Physics and Astronomy; University of Leeds; E. C. Stoner Building Leeds LS2 9JT UK
| | - Simon A. Barrett
- School of Chemistry; University of Leeds; Woodhouse Lane Leeds LS2 9JT UK
| | - Malcolm A. Halcrow
- School of Chemistry; University of Leeds; Woodhouse Lane Leeds LS2 9JT UK
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Kulmaczewski R, Cespedes O, Halcrow MA. Gradual Thermal Spin-Crossover Mediated by a Reentrant Z′ = 1 → Z′ = 6 → Z′ = 1 Phase Transition. Inorg Chem 2017; 56:3144-3148. [DOI: 10.1021/acs.inorgchem.7b00071] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Rafal Kulmaczewski
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Oscar Cespedes
- School of Physics
and Astronomy, University of Leeds, E. C. Stoner Building, Leeds LS2 9JT, U.K
| | - Malcolm A. Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
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Kulmaczewski R, Trzop E, Kershaw Cook LJ, Collet E, Chastanet G, Halcrow MA. The role of symmetry breaking in the structural trapping of light-induced excited spin states. Chem Commun (Camb) 2017; 53:13268-13271. [DOI: 10.1039/c7cc07990g] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Six isostructural compounds show differing agreement with the correlation T(LIESST) = T0 − 0.3T1/2 (red line; LIESST = Light-Induced Excited Spin-State Trapping). This reflects crystallographic symmetry breaking under LIESST conditions, exhibited by one of the compounds but not by two others.
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Affiliation(s)
| | - Elzbieta Trzop
- Institut de Physique de Rennes
- Université de Rennes 1
- UMR UR1-CNRS 6251
- F-35000 Rennes
- France
| | | | - Eric Collet
- Institut de Physique de Rennes
- Université de Rennes 1
- UMR UR1-CNRS 6251
- F-35000 Rennes
- France
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Kershaw Cook LJ, Kulmaczewski R, Mohammed R, Dudley S, Barrett SA, Little MA, Deeth RJ, Halcrow MA. A Unified Treatment of the Relationship Between Ligand Substituents and Spin State in a Family of Iron(II) Complexes. Angew Chem Int Ed Engl 2016; 55:4327-31. [PMID: 26929084 PMCID: PMC4804750 DOI: 10.1002/anie.201600165] [Citation(s) in RCA: 133] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Indexed: 11/10/2022]
Abstract
The influence of ligands on the spin state of a metal ion is of central importance for bioinorganic chemistry, and the production of base-metal catalysts for synthesis applications. Complexes derived from [Fe(bpp)2 ](2+) (bpp=2,6-di{pyrazol-1-yl}pyridine) can be high-spin, low-spin, or spin-crossover (SCO) active depending on the ligand substituents. Plots of the SCO midpoint temperature (T1/2 ) in solution vs. the relevant Hammett parameter show that the low-spin state of the complex is stabilized by electron-withdrawing pyridyl ("X") substituents, but also by electron-donating pyrazolyl ("Y") substituents. Moreover, when a subset of complexes with halogeno X or Y substituents is considered, the two sets of compounds instead show identical trends of a small reduction in T1/2 for increasing substituent electronegativity. DFT calculations reproduce these disparate trends, which arise from competing influences of pyridyl and pyrazolyl ligand substituents on Fe-L σ and π bonding.
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Affiliation(s)
- Laurence J Kershaw Cook
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | | | | | - Stephen Dudley
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK
| | - Simon A Barrett
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK
| | - Marc A Little
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK
| | - Robert J Deeth
- Inorganic Computational Chemistry Group, Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.
- School of Chemistry, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, UK.
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Kershaw Cook LJ, Kulmaczewski R, Mohammed R, Dudley S, Barrett SA, Little MA, Deeth RJ, Halcrow MA. A Unified Treatment of the Relationship Between Ligand Substituents and Spin State in a Family of Iron(II) Complexes. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201600165] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Laurence J. Kershaw Cook
- School of Chemistry; University of Leeds; Leeds LS2 9JT UK
- Department of Chemistry; University of Bath, Claverton Down; Bath BA2 7AY UK
| | | | | | - Stephen Dudley
- School of Chemistry; University of Leeds; Leeds LS2 9JT UK
| | | | - Marc A. Little
- School of Chemistry; University of Leeds; Leeds LS2 9JT UK
- Department of Chemistry; University of Liverpool; Crown Street Liverpool L69 7ZD UK
| | - Robert J. Deeth
- Inorganic Computational Chemistry Group; Department of Chemistry; University of Warwick; Coventry CV4 7AL UK
- School of Chemistry; University of Edinburgh; Joseph Black Building; David Brewster Road Edinburgh EH9 3FJ UK
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Kulmaczewski R, Halcrow MA. Structures and spin states of crystalline [Fe(NCS)2L2] and [FeL3]2+complexes (L = an annelated 1,10-phenanthroline derivative). CrystEngComm 2016. [DOI: 10.1039/c6ce00163g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Cook LJK, Kulmaczewski R, Cespedes O, Halcrow MA. Different Spin-State Behaviors in Isostructural Solvates of a Molecular Iron(II) Complex. Chemistry 2015; 22:1789-99. [DOI: 10.1002/chem.201503989] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Indexed: 11/07/2022]
Affiliation(s)
- Laurence J. Kershaw Cook
- School of Chemistry; University of Leeds; Woodhouse Lane Leeds LS2 9JT UK), Fax
- Department of Chemistry; University of Bath; Claverton Down Bath BA2 7AY UK)
| | - Rafal Kulmaczewski
- School of Chemistry; University of Leeds; Woodhouse Lane Leeds LS2 9JT UK), Fax
| | - Oscar Cespedes
- School of Physics and Astronomy; University of Leeds; E.C. Stoner Building Leeds LS2 9JT UK)
| | - Malcolm A. Halcrow
- School of Chemistry; University of Leeds; Woodhouse Lane Leeds LS2 9JT UK), Fax
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Santoro A, Kershaw Cook LJ, Kulmaczewski R, Barrett SA, Cespedes O, Halcrow MA. Iron(II) complexes of tridentate indazolylpyridine ligands: enhanced spin-crossover hysteresis and ligand-based fluorescence. Inorg Chem 2015; 54:682-93. [PMID: 25563430 DOI: 10.1021/ic502726q] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Reaction of 2,6-difluoropyridine with 2 equiv of indazole and NaH at room temperature affords a mixture of 2,6-bis(indazol-1-yl)pyridine (1-bip), 2-(indazol-1-yl)-6-(indazol-2-yl)pyridine (1,2-bip), and 2,6-bis(indazol-2-yl)pyridine (2-bip), which can be separated by solvent extraction. A two-step procedure using the same conditions also affords both 2-(indazol-1-yl)-6-(pyrazol-1-yl)pyridine (1-ipp) and 2-(indazol-2-yl)-6-(pyrazol-1-yl)pyridine (2-ipp). These are all annelated analogues of 2,6-di(pyrazol-1-yl)pyridine, an important ligand for spin-crossover complexes. Iron(II) complexes [Fe(1-bip)2](2+), [Fe(1,2-bip)2](2+), and [Fe(1-ipp)2](2+) are low-spin at room temperature, reflecting sterically imposed conformational rigidity of the 1-indazolyl ligands. In contrast, the 2-indazolyl complexes [Fe(2-bip)2](2+) and [Fe(2-ipp)2](2+) are high-spin in solution at room temperature, whereas salts of [Fe(2-bip)2](2+) exhibit thermal spin transitions in the solid state. Notably, [Fe(2-bip)2][BF4]2·2MeNO2 adopts a terpyridine embrace lattice structure and undergoes a spin transition near room temperature after annealing, resulting in thermal hysteresis that is wider than previously observed for this structure type (T1/2 = 266 K, ΔT = 16-20 K). This reflects enhanced mechanical coupling between the cations in the lattice through interdigitation of their ligand arms, which supports a previously proposed structure/function relationship for spin-crossover materials with this form of crystal packing. All of the compounds in this work exhibit blue fluorescence in solution under ambient conditions. In most cases, the ligand-based emission maxima are slightly red shifted upon complexation, but there is no detectable correlation between the emission maximum and the spin state of the iron centers.
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Affiliation(s)
- Amedeo Santoro
- School of Chemistry, University of Leeds , Woodhouse Lane, Leeds LS2 9JT, United Kingdom
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Kershaw Cook LJ, Kulmaczewski R, Barrett SA, Halcrow MA. Iron(ii) complexes of 4-sulfanyl-, 4-sulfinyl- and 4-sulfonyl-2,6-dipyrazolylpyridine ligands. A subtle interplay between spin-crossover and crystallographic phase changes. Inorg Chem Front 2015. [DOI: 10.1039/c5qi00083a] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The compound shown exhibits an abrupt thermal spin-transition, with an accompanying crystallographic phase change at slightly lower temperature which is visible as a shoulder on the susceptibility curve.
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Kulmaczewski R, Shepherd HJ, Cespedes O, Halcrow MA. A Homologous Series of [Fe(H2Bpz2)2(L)] Spin-Crossover Complexes with Annelated Bipyridyl Co-Ligands. Inorg Chem 2014; 53:9809-17. [DOI: 10.1021/ic501402q] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Rafal Kulmaczewski
- School
of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Helena J. Shepherd
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, U.K
| | - Oscar Cespedes
- School of Physics and Astronomy, University of Leeds, E. C. Stoner Building, Leeds LS2 9JT, U.K
| | - Malcolm A. Halcrow
- School
of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
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Kulmaczewski R, Olguín J, Kitchen JA, Feltham HLC, Jameson GNL, Tallon JL, Brooker S. Remarkable Scan Rate Dependence for a Highly Constrained Dinuclear Iron(II) Spin Crossover Complex with a Wide Thermal Hysteresis Loop. J Am Chem Soc 2014; 136:878-81. [DOI: 10.1021/ja411563x] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Rafal Kulmaczewski
- Department
of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago,
P.O. Box 56, Dunedin 9054, New Zealand
| | - Juan Olguín
- Department
of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago,
P.O. Box 56, Dunedin 9054, New Zealand
| | - Jonathan A. Kitchen
- Department
of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago,
P.O. Box 56, Dunedin 9054, New Zealand
| | - Humphrey L. C. Feltham
- Department
of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago,
P.O. Box 56, Dunedin 9054, New Zealand
| | - Guy N. L. Jameson
- Department
of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago,
P.O. Box 56, Dunedin 9054, New Zealand
| | - Jeffery L. Tallon
- MacDiarmid
Institute for Advanced Materials and Nanotechnology and Robinson Research
Institute, Victoria University of Wellington, P.O. Box 31310, Lower Hutt, New Zealand
| | - Sally Brooker
- Department
of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago,
P.O. Box 56, Dunedin 9054, New Zealand
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Kitchen JA, Olguín J, Kulmaczewski R, White NG, Milway VA, Jameson GNL, Tallon JL, Brooker S. Effect of N4-Substituent Choice on Spin Crossover in Dinuclear Iron(II) Complexes of Bis-Terdentate 1,2,4-Triazole-Based Ligands. Inorg Chem 2013; 52:11185-99. [DOI: 10.1021/ic4014416] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Jonathan A. Kitchen
- Department
of Chemistry and the MacDiarmid Institute for Advanced Materials and
Nanotechnology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Juan Olguín
- Department
of Chemistry and the MacDiarmid Institute for Advanced Materials and
Nanotechnology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Rafal Kulmaczewski
- Department
of Chemistry and the MacDiarmid Institute for Advanced Materials and
Nanotechnology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Nicholas G. White
- Department
of Chemistry and the MacDiarmid Institute for Advanced Materials and
Nanotechnology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Victoria A. Milway
- Department
of Chemistry and the MacDiarmid Institute for Advanced Materials and
Nanotechnology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Guy N. L. Jameson
- Department
of Chemistry and the MacDiarmid Institute for Advanced Materials and
Nanotechnology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Jeffery L. Tallon
- MacDiarmid
Institute for Advanced Materials and Nanotechnology, Callaghan Innovation, P.O. Box 31310, Lower Hutt 5040, New Zealand
| | - Sally Brooker
- Department
of Chemistry and the MacDiarmid Institute for Advanced Materials and
Nanotechnology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
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Barreira-Fontecha J, Kulmaczewski R, Ma X, McKee V. Double template effect in [4 + 4] Schiff base macrocycle formation; an ESI-MS study. Dalton Trans 2011; 40:12040-3. [DOI: 10.1039/c1dt11341k] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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